Liebert Power Supply PDUTM User Manual

POWER DISTRIBUTION  
STS2/PDU™  
INSTALLATION, OPERATION & MAINTENANCE MANUAL  
250A - 800A  
Three Phase  
60 Hz  
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TABLE OF CONTENTS  
7.0  
i
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ii  
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iii  
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FIGURES  
Figure 1  
iv  
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v
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TABLES  
vi  
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IMPORTANT SAFETY INSTRUCTIONS  
SAVE THESE INSTRUCTIONS  
This manual contains important instructions that should be followed during the installation and  
maintenance of the Liebert Static Transfer Switch 2 Power Distribution Unit (STS2/PDU).  
Read this manual thoroughly, paying special attention to the sections that apply to your installation,  
before working with the Static Transfer Switch 2 Power Distribution Unit. Retain this manual for use  
by installing personnel.  
Refer to 1.2.1 - Handling Considerations before attempting to move the unit.  
WARNING  
!
The unit is supplied by more than one power source. The unit contains hazardous voltages if  
any of the input sources are on, even when the unit is in bypass. To isolate the unit, turn off  
and lock out all input power sources.  
Verify that all input power sources are de-energized and locked out before making connections  
inside unit.  
Lethal voltages exist inside the unit during normal operation. Only qualified service  
personnel should perform maintenance on the STS2/PDU.  
NOTE  
Read the entire manual before installing or operating the system. Adhere to all operating  
instructions and warnings on the unit and in this manual.  
WARNING  
!
Under typical operation and with all STS2/PDU doors closed, only normal safety precautions  
are necessary. The area around the STS2/PDU should be kept free of puddles of water, excess  
moisture and debris.  
ONLY qualified service personnel should perform maintenance on the Static Transfer  
Switch 2 Power Distribution Unit. When performing maintenance on any part of the  
equipment under power, service personnel and test equipment should be located on rubber  
mats. The service personnel should wear insulating shoes for isolation from direct contact  
with the floor.  
One person should never work alone, even if all power is removed from the equipment. A  
second person should be standing by to assist and summon help in case an accident should  
occur.  
WARNING  
!
The input sources to the STS2/PDU must be grounded-wye sources. Input sources other than  
solidly grounded-wye sources may cause damage to the switch.  
Liebert Corporation neither recommends nor knowingly sells this product for use with life support or  
other FDA-designated “critical” devices.  
The Static Transfer Switch 2 Power Distribution Unit is suitable for indoor use only. Protect the unit  
from excessive moisture and install the unit in an area free from flammable liquids, gases and corro-  
sive substances.  
The unit is designed to operate from solidly grounded AC power sources only. Provide input over-cur-  
rent protection in accordance with the unit ratings. Wire and ground the unit according to national  
and local electrical safety codes. All wiring should be installed by a qualified electrician.  
1
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A thorough equipment inspection and supervised start-up by qualified service personnel are strongly  
recommended at these times:  
1. Before unit is placed into service for the first time  
2. After equipment relocation, and  
3. After the unit has been de-energized for an extended period of time  
CAUTION  
!
This unit complies with the limits for a Class A digital device, pursuant to Part 15 Subpart J  
of the FCC rules and EN550022. These limits provide reasonable protection against harmful  
interference in a commercial environment. This unit generates, uses and radiates radio  
frequency energy and, if not installed and used in accordance with this instruction manual,  
may cause harmful interference to radio communications. Operation of this unit in a  
residential area may cause harmful interference that the user must correct at his own  
expense.  
WARNING  
!
Locate the center of gravity symbols and determine the unit’s weight  
before handling the cabinet.  
2
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Unpacking and Inspections  
1.0 UNPACKING AND INSPECTIONS  
NOTE  
Read the entire manual before beginning to install the STS2/PDU. Upon delivery of the  
STS2/PDU, the installer should perform the following steps to ensure a high-quality  
installation.  
A high-quality installation begins on the receiving dock. The STS2/PDU and its packaging should be  
inspected when the unit is delivered. If the packaging is not damaged, unpack the unit and conduct-  
ing internal inspection before beginning the installation process. This section discusses inspecting  
and unpacking the STS2/PDU.  
1.1  
External Inspections  
1. While the STS2/PDU is still on the truck, inspect the equipment and shipping container(s) for any  
signs of damage or mishandling. Do not attempt to install the system if damage is apparent.  
2. Upon receipt and before unpacking, inspect the shipping crate for damage or mishandling.  
Check the Shock-Watch™ indicator.  
If the indicator is red, note on shipper’s receipt and check for concealed damage.  
If any damage as a result of shipping is observed, file a damage claim with the shipper within 24 hours  
and contact your local Liebert representative or Liebert Global Services at 1-800-543-2378 to  
inform them of the damage claim and the condition of the equipment.  
3. Locate the bag containing the keys for the front access door. The bag is attached to the cabinet.  
4. Compare the contents of the shipment with the bill of lading. Report any missing items to the  
carrier and to Liebert Global Services immediately.  
5. Check the nameplate on the cabinets to verify that the model numbers correspond with the one  
specified. Record the model numbers and serial numbers in the front of this installation manual.  
A record of this information is necessary should servicing be required.  
6. If unit is to be stored before installation, it is recommended to store the unit in a dry environment  
with temperatures in the range of -40 to 176°F (-40 to 80°C). Use original packing materials or  
other suitable means to keep the unit clean. When opening the shipping crate, use care not to  
puncture the container with sharp objects.  
1.2  
Unloading and Handling  
CAUTION  
!
When moving the unit by forklift, lift the unit from the rear so as to protect the front panel.  
Do not exceed a 15 degree tilt with the forklift.  
Also, if you are moving the unit by forklift or pallet jack after it has been removed from the  
pallet, be aware of the location of the casters and leveling feet (if unit is so equipped) so as not  
to damage them.  
Most STS2/PDU models are contained in one cabinet. The 800 amp units are contained in two cabi-  
nets that shipped on two pallets and connected together in the field.  
The unit can be moved by forklift or pallet jack. However, because the weight distribution in the cabi-  
net is uneven, use extreme care during handling and transporting.  
See 1.2.2 - Unit Preparation for instructions on removing the STS2/PDU from the pallet.  
3
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Unpacking and Inspections  
1.2.1 Handling Considerations  
The STS2/PDU is bolted to a wood shipping pallet to allow handling by forklift equipment or a pallet  
jack.  
WARNING  
!
Exercise extreme care when handling STS2/PDU cabinets to avoid equipment damage or  
injury to personnel.  
The cabinet can be safely tilted 15 degrees in any direction by forklift.  
If moving the unit up a ramp on its casters (if the unit is so equipped) or a pallet jack, ensure  
that the incline does not exceed 15 degrees.  
Locate the center of gravity symbols and determine the unit’s weight  
the cabinet.  
before handling  
Check the unit size and weight. Refer to the cabinet drawings furnished with the unit for size and  
weight. Typical cabinet dimensions are shown in Figures 7 through 22. Typical unit crated weights  
are:  
Table 1  
Shipping weights (typical)  
Model  
Weight - lbs. (kg)  
3730 lbs. (1692 kg)  
4900 lbs. (2132 kg)  
5580 lbs. (2531 kg)  
4052 lbs. (1838 kg)  
4595 lbs. (2084 kg)  
250A  
400A  
600A  
800A Module A*  
800A Module B*  
*800A ships on two separate pallets  
Plan the route. Review the route over which the unit will be transported to its installation location to  
ensure that all passages are large enough to accommodate the unit and support the weight.  
Check for any non-negotiable corners or offsets in hallways. Before moving the unit to the intended  
location, review 2.0 - Location Considerations.  
1.2.2 Unit Preparation  
The unit can be removed from the pallet before it is moved to its location.  
Complete the following steps to properly remove the STS2/PDU from the shipping pallet:  
1. Set the pallet in a level area with enough room to maneuver and remove the unit.  
2. Remove the bolts holding the unit to the shipping pallet (located in the base of the unit).  
3. Remove the shipping blocks from under the frame of the unit.  
4. Use a forklift to raise the unit off the pallet and onto the floor. On the 250A unit ensure that the  
forklift is clear of the unit's casters and leveling feet. Lift the unit from the rear.  
5. Conduct an internal inspection of the unit. See the list in 1.3 - Internal Inspections.  
1.3  
Internal Inspections  
After the STS2/PDU has been unpacked, conduct an internal inspection:  
1. Verify that all items have been received.  
2. If spare parts were ordered, verify their arrival.  
3. After the Static Transfer Switch 2 Power Distribution Unit has been removed from the pallet,  
open the door and remove cabinet panels to check for shipping damage to internal components.  
4. Check for loose connections or unsecured components in the cabinet(s).  
5. Check for any unsafe condition that may be a potential safety hazard.  
After the STS2/PDU has been inspected and no problems are found, the unit can be moved to its  
installation location. If using a forklift, remember to lift the unit from the rear.  
4
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Location Considerations  
2.0 LOCATION CONSIDERATIONS  
The STS2/PDU should be placed in a clean, cool and dry location. The 250A unit without an output  
cabinet requires only front access for installation and maintenance. Both front and side access are  
required for installation and maintenance of 400-800A units and 250A units with output cabinet. The  
output cabinet comes factory installed or either the right or left side depending on how it was ordered.  
It cannot be moved from one side to the other in the field.  
Adequate space is required above the unit for conduit (if configured as such) and cooling air flow. This  
section provides specific information for these considerations.  
The unit is designed with top and bottom cable terminations to allow maximum flexibility in its  
installation. Units with output inline panelboards are bottom exit only. If bottom cable entry and exit  
is used, sufficient cable bending space must be provided by a raised floor or a floor stand.  
For dimensions of each unit, see Figures 7 through 22. If your unit is equipped with an optional key  
lockout switch, see Figures 13 through 21 for the location of that switch.  
2.1  
2.2  
Recommended Minimum Service Clearances  
The recommended service clearances are at the front and side, if equipped with output cabinet. The  
minimum service clearance required by the National Electrical Code (NEC) Article 110-26 is  
36 in. (91cm) for units with voltages up to 150V to ground and 42 in. (107cm) for units with voltages  
over 150V to ground. Clearance of at least 18 in. (46cm) is required above the unit for cooling air flow.  
Heat Output  
The unit produces minimal heat during normal operation.  
Table 2  
Heat output  
Heat Output  
BTU/Hr (kW)  
Switch Size  
250A  
400A  
600A  
800A  
12,590 (3.69)  
20,140 (5.90)  
30,200 (8.85)  
40,270 (11.80)  
2.3  
Operating Environment  
The unit is designed to be installed indoors where the ambient air temperature is in the range of  
32° to 104°F (0°C - 40°C) with a relative humidity of 0% to 95% non-condensing, up to an altitude of  
4000 feet (1200 meters).  
5
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Location Considerations  
2.4  
Altitude  
The standard units are designed for full load operation up to 4000 feet (1200m) above sea level. See  
Figure 1 for recommended deratings for altitudes greater than 4000 feet (1200m).  
Figure 1 Recommended derating for high altitude operation  
100  
98  
96  
94  
92  
90  
88  
86  
Operation at full load at a higher altitude can be accommodated in ambient temperatures less than  
104°F (40°C) ambient. Figure 2 shows the maximum allowable ambient temperature for full load  
operation at altitudes above 4000 feet (1200m).  
Figure 2 Maximum ambient temperature for full load operation at higher altitudes  
104.0 (40)  
102.2 (39)  
100.4 (38)  
98.6 (37)  
96.8 (36)  
95.0 (35)  
93.2 (34)  
94.1 (33)  
89.6 (32)  
87.8 (31)  
86.0 (30)  
Altitude—Feet  
Table 3  
Altitude conversion—feet to meters  
Feet = Meters  
4000 = 1200  
4500 = 1372  
5000 = 1524  
5500 = 1676  
6000 = 1829  
6500 = 1981  
7000 = 2134  
7500 = 2286  
8000 = 2438  
8500 = 2591  
9000 = 2743  
9500 = 2896  
10000 = 3048  
6
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Locating The STS2/PDU  
3.0 LOCATING THE STS2/PDU  
This section provides instructions for leveling the STS2/PDU and anchoring the unit to the floor,  
should that be required.  
3.1  
3.2  
Anchoring the Unit to the Floor  
The STS2/PDU can be anchored to the concrete floor to ensure stability for the unit in the event of  
seismic activity.  
Leveling of the 250A Only STS2/PDU Without Anchoring  
The 250A Static Transfer Switch 2 Power Distribution Unit is furnished with casters and leveling  
feet. After final positioning of the unit, adjust the leveling feet located in each corner of the frame base  
to level and stabilize the unit.  
For leveling feet details, see Figures 7 through 11.  
7
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Power and Control Wiring  
4.0 POWER AND CONTROL WIRING  
All power and control wiring must be installed by a licensed, qualified electrician. All power and con-  
trol wiring must comply with the National Electrical Code and all applicable local codes. Unless oth-  
erwise labeled, use the recommended tightening torque shown in Table 29.  
The input power busbars are accessible through the front of the unit. Liebert’s 250A units have PEM  
nut inserts designed to allow one-handed tightening. Busbars in the 400-800A units are supplied with  
holes to accommodate two-hole lugs.  
Cables can be installed through the top or bottom of the unit through removable conduits plates.  
Units with output inline panelboards are bottom exit only for output cables.  
See Figures 12 through 21 for wiring entrance locations.  
4.1  
Input and Output Power Connections  
The input power connections are made to the busbars provided inside the unit (see Figures 26  
through 31). These busbars are accessible through the front of the unit.  
Output power connections are handled two different ways, depending on the type of distribution used.  
Power connections on standard units with an output breaker are made to the busbars inside the unit.  
These busbars are accessible through the front on 250A units and on the side on 400-800A units. See  
Figures 26 through 31 for details on the busbars. Power connections on units with panelboard distri-  
bution are made directly to the panelboard breakers. Busbars are provided in the output cabinet for  
ground and neutral connections.  
WARNING  
!
Verify that all input power and control circuits are de-energized and locked out before making  
connections inside unit.  
The two input power feeds (sources) to the STS2/PDU should be from two independent sources to  
avoid a common source failure.  
To ensure proper operation of the STS2/PDU, the two input sources must be the same nominal volt-  
age level and phase rotation.  
For uninterrupted automatic transfer, the two input sources should be synchronized within  
15 degrees.  
CAUTION  
!
The input sources to the STS2/PDU must be grounded-wye sources. Input sources other than  
solidly grounded-wye sources may cause damage to the switch.  
The STS2/PDU is designed for operation with 3-wire, solidly grounded sources only.  
See Figures 3 through 6 for typical one-line diagrams. Refer to Figures 26 through 31 for electrical  
field connections on all units.  
8
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Power and Control Wiring  
Figure 3 Typical STS2/PDU, one-line diagram  
Figure 4 Typical STS2/PDU, one-line diagram, with dual static switch output circuit breakers  
(not available on 250A units)  
9
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Power and Control Wiring  
Figure 5 Typical STS2/PDU, one-line diagram, with inline distribution, dual static switch output circuit  
breakers  
Figure 6 Typical STS2/PDU, one-line diagram, with I-Line distribution, dual static switch output circuit  
breakers  
The input and output power wire size should be based on the overcurrent protection device, observing  
the NEC and local codes.  
The STS2/PDU output power, ground and neutral busbars accommodate a wide range of wire sizes.  
The STS2/PDU busbars accommodate standard two-hole lugs.  
Table 4  
Input/output conduit plate specifications  
Maximum Number  
Rating  
of Conduits  
Size, in.  
2"  
12  
8
250A  
2-1/2"  
6
3" or 3-1/2"  
2"  
6
400-600A  
800A  
4
2-1/2" or 3"  
2-1/2"  
6
5
3" or 3-1/2"  
10  
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Power and Control Wiring  
4.2  
System Grounding  
Equipment grounding—Grounding is primarily for equipment and personnel safety, although proper  
grounding also enhances equipment performance.  
All input and output power feeds must include an equipment grounding means as required by the  
NEC and local codes.  
An insulated equipment ground conductor is recommended to run with each input and output power  
feed. The equipment ground conductors should be at least the minimum size conductor per the NEC  
based on the upstream overcurrent protection device.  
WARNING  
!
If conduit is used as a grounding means, adequate electrical continuity must be maintained at  
all conduit connections. The use of isolating bushings with a metal conduit can be a safety  
hazard and is not recommended.  
4.3  
Control Wiring Connections  
No control wiring is needed on the standard STS2/PDU. Certain options and remote monitoring con-  
figurations require external control wiring. See 6.0 - Options for details.  
The customer must supply control wiring to the STS2/PDU for connection to any monitoring or com-  
munication options. Top and bottom removable conduit plates are provided for control wiring conduit.  
Control cables can be installed through the top or bottom of the unit through removable control con-  
duit plates. A top hat is provided on the 400-600A units for connecting the top entry control wiring  
conduits (see Figures 13 through 21). The top hat is turned upside down and ships inside the unit. It  
must be removed from the unit and flipped 180 degrees before being reinstalled (see Figure 49). The  
control wiring top hat does NOT contain any knockouts for conduit. The installer must drill the  
appropriate-sized holes for the conduit before attaching to the top of the STS2/PDU.  
See Figures 47 and 48 for arrangement of optional cards.  
4.4  
Remote Source Selection Wiring  
An optional Remote Source Selection board may be installed in your STS2/PDU. This board is installed  
in the same bay as the communications options. See Figures 47 and 48 for the location of these  
options. See Figure 56 for information on the control wiring for the Remote Source Selection option.  
The Remote Source Selection allows you choose the preferred input source from a remote location.  
Terminal connections allow the customer to remotely select a source to be the preferred source in the  
same process as the local source transfer selection.  
If both the input contacts are closed, the current selected preferred source shall be retained. If the  
unit’s preferred source selection and Remote Source Selection are active at the same time,  
the STS2/PDU follows the last request for a preferred source change, regardless of whether it was  
from the local or Remote Source Selection controls.  
A six pin terminal block provides the Remote Source Selection connections. Two pairs of wires are  
used from the switch to trigger the source selection. You can select the type of switch used for this  
remote control. Connections are made to four of the connections, using Form A dry contacts. The con-  
tacts are numbered left to right:  
Table 5  
Contact  
Remote source selection terminal block  
Connection  
Source 1  
1
2
3
4
5
6
Isolated ground  
Source 2  
Isolated Ground  
DO NOT USE  
DO NOT USE  
See 10.3 - Enabling Remote Source Selection for instructions on enabling the Remote Source  
Selection option.  
11  
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Power and Control Wiring  
4.5  
Power Supply  
The STS2/PDU is supplied with redundant power supplies that are designed to operate from a voltage  
range of 200V to 600V. The unit is set at the factory to match the nameplate voltage. Field adjust-  
ments are not necessary. If the unit needs to operate at a voltage other than what is listed on the  
nameplate, contact Liebert Global Services or your local Liebert representative. Table 6 provides  
transformer tap information.  
Table 6  
Terminal block 1 and terminal block 2 wire connections  
Connect Connect  
Voltage F1 TB1-XX F2 TB1-YY F3 TB2-XX F4 TB2-YY Jumper Between  
200  
220  
380  
415  
600  
208  
240  
400  
480  
1
2
1
1
1
1
1
1
1
9
1
2
1
1
1
1
1
1
1
9
1-7  
6-8  
2-7  
4-7  
6-7  
1-7  
1-7  
3-7  
5-7  
12  
8
12  
8
10  
12  
10  
11  
9
10  
12  
10  
11  
9
11  
11  
CAUTION  
!
Using Table 6, ensure that the wiring for the control transformers matches the input voltage  
for the unit.  
Improper wiring could result in blown fuses.  
12  
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Output Power Wiring  
5.0 OUTPUT POWER WIRING  
The STS2/PDU standard model is provided with a circuit breaker for connecting to the load or a  
remote distribution cabinet. Other distribution configurations are available.  
The three main types of distributions available for the STS2/PDU are:  
Output Breaker  
Inline Panelboards—two panelboards (84 poles) on 250A units and four panelboards (168 poles)  
®
on 400-800A units. Square D and General Electric panelboards are available to accommodate  
bolt-in or plug-in breakers.  
®
Square D I-Line Panelboard—designed to accommodate up to 10 plug-in breakers from 100A  
to 250A. Additionally, 300A to 400A breakers are available on 800A units.  
For other optional distribution methods, contact your local Liebert representative or call  
1-800-LIEBERT.  
The STS2/PDU distribution may be mounted on either the right or left side at the customer’s option.  
Location of output conduit connections is affected by the location of the output cabinet. See  
Figures 8, 9, 12, 13, 16 and 17 for wiring a right-side distribution configuration and  
Figures 10, 11, 14, 15, 18 and 19 for wiring a left-side distribution configuration. See Figures 23  
through 44 for wiring.  
See Table 7 for wiring the various output options.  
5.1  
Customer Connections  
The customer is responsible for connections from the STS2/PDU distribution to the connected load,  
either directly or through remote distribution cabinets.  
Table 7  
Distribution configurations  
For Details See  
Electrical Output  
Field Connections  
Distribution Type  
Output Breaker  
250A  
400-600A  
800A  
Inline Panelboards  
250A  
400-800A  
I-Line (Square D)  
13  
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Options  
6.0 OPTIONS  
This section discusses the options available for the STS2/PDU. The communications options are also  
WARNING  
!
All options must be installed by Liebert Global Services or Liebert factory-authorized service  
provided by a Liebert distributor. The option area and customer control cable area contain  
hazardous voltages if any of the input sources are on, even when the unit is in bypass. Turn  
OFF all power sources before installing customer control cables to any option.  
6.1  
Programmable Relay Board  
The programmable relay board (PRB) provides a means to trigger an external device when an event  
occurs in the STS2/PDU. Each PRB has 8 channels. Each channel has two sets of Form-C dry con-  
tacts, rated 1A @ 30VDC or 250mA @ 125VAC.  
Any alarm or event may be programmed to any channel or channels. Up to ten (10) events may be  
programmed to a relay. If multiple events are grouped to one relay, group the events logically to sim-  
plify troubleshooting when an event is triggered. The same alarm or event may be programmed to  
more than one channel. Up to two programmable relay boards can be installed in the STS2/PDU for a  
total of 16 channels. Programming is performed through the touch screen display.  
instructions for reconfiguring the relays. See Figures 47 and 48 for the location of the PRB. See  
Figure 50 for wiring details. Table 8 provides the PRB pinout.  
Table 8  
Programmable relay board pinout  
Channel  
Pin No.  
1-3  
C
1
N.C.  
2
N.O.  
3
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
CH1  
4-6  
4
5
6
7-9  
7
8
9
TB1  
CH2  
CH3  
CH4  
CH5  
CH6  
CH7  
CH8  
10-12  
13-15  
1-3  
10  
13  
1
11  
14  
2
12  
15  
3
4-6  
4
5
6
7-9  
7
8
9
TB2  
10-12  
13-15  
1-3  
10  
13  
1
11  
14  
2
12  
15  
3
4-6  
4
5
6
7-9  
7
8
9
TB3  
TB4  
10-12  
13-15  
1-3  
10  
13  
1
11  
14  
2
12  
15  
3
Key: N.O. = Normally Open; N/C. = Normally Closed; C = Common  
Note: Pin 16 not used on TB1, TB2 and TB3.  
6.2  
Input Contact Isolator Board  
The Input Contact Isolator Board (ICI) provides an STS2/PDU module interface for up to eight exter-  
nal user alarm or message inputs to be routed through the Static Transfer Switch 2 Power Distribu-  
tion Unit’s alarm network. The eight contacts are normally open dry contacts. When a contact closes,  
an event is triggered.  
The Input Contact Isolator options are configured through the Input Contact Isolator dialog box,  
which is accessed from the Comm Option dialog box on the touch screen display. You also can pro-  
gram the alarm messages through this dialog box. See Configuring the Input Contact Isolator  
Settings on page 108 for instructions on configuring the connections.  
See Figures 47 and 48 for the location of the ICI. See Figure 51 for wiring details.  
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Options  
6.3  
Comms Board  
The Comms Board provides a communication interface to Liebert SiteScan, site monitoring product  
and/or an external or internal modem. SiteLink-12 or SiteLink-4 is required for SiteScan to communi-  
cate with the STS2/PDU.  
The Comms Board is equipped with an RS-422 communication port for communication to a Liebert  
SiteScan monitoring system using a 2-wire twisted pair for reliable communication up to 1000 meters  
(3281 feet). Information available from the RS-422 port includes the present switch status informa-  
tion, all monitoring parameters and all active alarms.  
The Comms Board is equipped with a modem interface for remote reporting of the present switch sta-  
tus information, alarm history information and the history of status screens that are triggered upon a  
major alarm event. The monitoring system software also supports an auto-dial feature that allows the  
system to automatically dial programmed phone numbers by way of the modem to report designated  
alarm conditions.  
Programming the Comms Board is performed through the touch screen display. See Comm  
Options on page 105 for details.  
See Figures 47 and 48 for the location of the Comms Board. See Figure 52 for information on the  
control wiring.  
6.4  
Internal Modem  
The Internal Modem is an option that must be ordered separately. An external modem is available  
from third party sources. The Internal Modem is capable of dialing out from the STS2/PDU or accept-  
ing incoming calls and connecting to a remote terminal or computer. Using an ASCII Query and  
Answer format the modem connection can be used to view system status and alarms. The modem pro-  
vides all information normally available on the LCD of the STS2/PDU. No control functions are avail-  
able via the modem, such as making transfers, selecting a preferred source or changing  
configurations.  
The modem can also be configured to dial out two different telephone numbers (any combination of  
modem or pager numbers).  
The connection to this modem is through a standard RJ-11 port.  
See Figures 47 and 48 for the location of the internal modem. See Figure 53 for more information on  
the internal modem.  
Programming the modem is performed through the touch screen display, see Configuring the  
Modem on page 105 for details.  
The modem commands are shown in Table 13.  
6.5  
Network Interface Card (NIC)  
An OpenComms Network Interface Card (NIC) enables the STS2/PDU to communicate to a network  
management system (NMS). The NIC provides the internal hardware and software to communicate,  
via SNMP, to any I.P.-based Ethernet network through an RJ-45 connector using Category 5 cabling.  
The NIC provides redundant paths for communications that make it possible to connect to a Building  
Management System (BMS) using Modbus, while simultaneously communicating to a NMS through  
SNMP. A terminal block provides the connection to Modbus.  
See Figures 47 and 48 for the location of the NIC. See Figure 54 for control wiring information.  
If you have questions about the NIC, refer to the OpenComms Network Interface Card Installation  
and Users Guide.  
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Options  
6.6  
Remote Source Selection  
The Remote Source Selection allows the preferred input source to be chosen from a remote location. A  
user supplied normally open dry contact allows the user to remotely select a source to be the preferred  
source in the same process as the local source transfer selection.  
If both the input contacts are closed, the current selected preferred source shall be retained. If the  
unit’s preferred source selection and Remote Source Selection are active at the same time,  
the STS2/PDU follows the last request for a preferred source change, regardless of whether it was  
from the local or Remote Source Selection controls.  
See 10.3 - Enabling Remote Source Selection for instructions on enabling the Remote Source  
Selection.  
See Figures 47 and 48 for the location of the Remote Source Selection option.  
See 4.4 - Remote Source Selection Wiring and Figure 56 for information on the control wiring.  
6.7  
Key Lockout Switch  
The key lockout switch activates a software lockout of the touch screen display to prevent manual  
transfers and configuration changes. When locked out, the touch screen becomes a read-only display.  
A key is needed to do manual transfers or change settings.  
The alarm silence button is not disabled when in the lockout position.  
The switch is located on the front of the unit next to the display; it is behind the front door but can be  
operated without opening the front door. See Figures 20 through 22 for the key lockout switch loca-  
tion on each unit.  
See 13.2.1 - Security and Figure 65 for instructions on using the key lockout switch.  
6.8  
6.9  
Static Switch Redundant Output Breaker  
A plug-in, non-automatic circuit breaker is provided which allows redundancy in the static switch out-  
put power path. The breaker is connected in parallel with the static switch output plug-in non-auto-  
matic circuit breaker.  
Inline Panelboards  
An output distribution cabinet with either Square D or General Electric inline panelboards with cop-  
per bus to accept bolt-in or plug-in circuit breakers. Each panelboard is individually protected by a  
225A, 240V, 3-pole panelboard main circuit breaker.  
Each panelboard includes a separate isolated neutral bus bar and a safety-ground bus bar for the neu-  
tral and safety-ground connections for at least 42 output circuits.  
6.10 I-Line Panelboards  
An output distribution cabinet with one vertically mounted Square D I-Line panelboard with copper  
bus to accept Square D three phase plug-in circuit breakers. The panelboard shall be totally enclosed  
with an accent cover.  
6.11 Subfeed Breakers  
Breakers for feeding remote panelboard(s) or other loads. Available in ratings of 225A or 400A.  
NOTE  
Only available on units with inline panelboards. 400A breaker not available on 250A units.  
6.12 K-Factor Transformers  
K20-rated double-shielded copper isolation transformer specially designed to accommodate highly  
nonlinear leads in accordance with UL 1561 (in place of standard isolation transformer).  
6.13 Surge Suppression System  
A fused and monitored high-energy, 80 kAmp/phase surge suppression system by Control Concepts  
connected to each input of the unit for superior surge suppression.  
16  
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Installation Drawings  
7.0 INSTALLATION DRAWINGS  
Figure 7 Outline drawing, 250A STS2/PDU  
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Installation Drawings  
Figure 8 Outline drawing, 250A STS2/PDU with right side I-Line distribution  
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Installation Drawings  
Figure 9 Outline drawing, 250A STS2/PDU with right side inline distribution  
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Installation Drawings  
Figure 10 Outline drawing, 250A STS2/PDU with left side I-Line distribution  
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Installation Drawings  
Figure 11 Outline drawing, 250A STS2/PDU with left side Inline distribution  
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Installation Drawings  
Figure 12 Outline drawing,400-600A STS2/PDU with right side inline distribution  
22  
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Installation Drawings  
Figure 13 Outline drawing, 400-600A STS2/PDU with right side output breaker or I-Line distribution  
23  
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Installation Drawings  
Figure 14 Outline drawing, 400-600A STS2/PDU with left side inline distribution  
24  
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Installation Drawings  
Figure 15 Outline drawing, 400-600A STS2/PDU with left side output breaker or I-Line distribution  
25  
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Installation Drawings  
Figure 16 Outline drawing, 800A STS2/PDU with right side output breaker or I-Line distribution  
26  
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Installation Drawings  
Figure 17 Outline drawing, 800A STS2/PDU with right side inline distribution  
27  
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Installation Drawings  
Figure 18 Outline drawing, 800A STS2/PDU with left side output breaker or I-Line distribution  
28  
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Installation Drawings  
Figure 19 Outline drawing, 800A STS2/PDU with left side inline distribution  
29  
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Installation Drawings  
Figure 20 Outline drawing, 250A STS2/PDU with key lockout switch option  
30  
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Installation Drawings  
Figure 21 Outline drawing, 400-600A STS2/PDU, inline distribution, right side with key lockout switch option  
31  
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Installation Drawings  
Figure 22 Outline drawing, 800A STS2/PDU, inline distribution, right side with key lockout switch option  
32  
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Installation Drawings  
Figure 23 Electrical field connections, 250A STS2/PDU input/output with CB8  
33  
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Installation Drawings  
Figure 24 Electrical field connections, 250A STS2/PDU input with CB3  
34  
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Installation Drawings  
Figure 25 Electrical field connections, 250A STS2/PDU input with CB3 & CB3A  
35  
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Installation Drawings  
Figure 26 Electrical field connections, 400-600A STS2/PDU input with CB3  
36  
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Installation Drawings  
Figure 27 Electrical field connections, 400-600A STS2/PDU input with CB3 and CB3A  
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Installation Drawings  
Figure 28 Electrical field connections, 800A STS2/PDU input with CB3  
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Installation Drawings  
Figure 29 Electrical field connections, 800A STS2/PDU input with CB3 and CB3A  
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Installation Drawings  
Figure 30 Electrical field connections, 250A STS2/PDU output with inline panelboards  
40  
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Installation Drawings  
Figure 31 Electrical field connections, 400-800A STS2/PDU output with inline panelboards  
41  
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Installation Drawings  
Figure 32 Electrical field connections, STS2/PDU output with I-Line panelboard  
42  
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Installation Drawings  
Figure 33 Electrical field connections, 400-600A STS2/PDU with right side output breaker  
43  
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Installation Drawings  
Figure 34 Electrical field connections, 400-600A STS2/PDU with left side output breaker  
44  
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Installation Drawings  
Figure 35 Electrical field connections, 800A STS2/PDU with right side output breaker  
45  
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Installation Drawings  
Figure 36 Electrical field connections, 8600A STS2/PDU with left side output breaker  
46  
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Installation Drawings  
Figure 37 Electrical field connections, 800A STS2/PDU interconnect wiring  
47  
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Installation Drawings  
Figure 38 Electrical field connections, 800A STS2/PDU interconnect wiring, breaker section  
48  
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Installation Drawings  
Figure 39 Electrical field connections, 800A STS2/PDU interconnect wiring, STS section  
49  
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Installation Drawings  
Figure 40 Electrical field connections, 800A STS2/PDU interconnect wiring, left side distribution cabinet  
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Installation Drawings  
Figure 41 Electrical field connections, 800A STS2/PDU interconnect wiring, left side one-line  
51  
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Installation Drawings  
Figure 42 Electrical field connections, 800A STS2/PDU interconnect wiring, left side one line with CB3A  
52  
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Installation Drawings  
Figure 43 Electrical field connections, 800A STS2/PDU interconnect wiring, right side one line  
53  
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Installation Drawings  
Figure 44 Electrical field connections, 800A STS2/PDU interconnect wiring, right side one line with CB3A  
54  
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Installation Drawings  
Figure 45 Control wiring, 800A STS2/PDU, left side distribution  
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Installation Drawings  
Figure 46 Control wiring, 800A STS2/PDU, right side distribution  
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Installation Drawings  
Figure 47 Control connection location, 250A STS2/PDU  
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Installation Drawings  
Figure 48 Control connection location, 400-800A STS2/PDU  
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Installation Drawings  
Figure 49 Control location drawing conduit box, top entry, 400-600A STS2/PDU  
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Installation Drawings  
Figure 50 Control wiring for the programmable relay board option  
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Installation Drawings  
Figure 51 Control wiring for the input contact isolator board option  
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Installation Drawings  
Figure 52 Control wiring for comms board  
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Installation Drawings  
Figure 53 Control wiring for the internal modem option  
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Installation Drawings  
Figure 54 Control wiring for the Network Interface Card (NIC) option  
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Installation Drawings  
Figure 55 Control wiring for the RS-232 Port  
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Installation Drawings  
Figure 56 Control wiring for remote source selection option  
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Installation Drawings  
Figure 57 Color LCD touch screen display  
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Installation Drawings  
Table 9  
STS2/PDU  
Input circuit breaker schedule, 250-800A  
Circuit Breakers  
STS2/PDU  
Input Volts  
(See One-Line  
Diagrams)  
Interrupting  
Rating (Amps)  
Rating  
Vendor  
Type  
NJHN  
NFNN  
NFNN  
NJHN  
NJHN  
NJHN  
NJHN  
NJHN  
NJHN  
Ampacity  
400A  
150A  
125A  
250A  
200A  
400A  
300A  
500A  
400A  
Voltage  
208-240V  
380-480V  
600V  
208V  
480V  
600V  
480V  
600V  
480V  
600V  
480V  
600V  
100K  
35K  
18K  
65K  
25K  
65K  
25K  
65K  
25K  
MERLIN  
GERIN  
250A  
CB6 & CB7  
380-480V  
600V  
MERLIN  
GERIN  
400A  
600A  
800A  
CB6 & CB7  
CB6 & CB7  
CB6 & CB7  
380-480V  
600V  
MERLIN  
GERIN  
380-480V  
600V  
MERLIN  
GERIN  
Table 10 Output circuit breaker schedule, 250-800A  
Circuit Breakers  
STS2/PDU  
Rating  
STS2/PDU  
Input Volts  
(See One-Line  
Diagrams)  
Interrupting  
Rating (Amps)  
Vendor  
Type  
Ampacity  
Voltage  
MERLIN  
GERIN  
250A  
400A  
600A  
800A  
208V  
208V  
208V  
208V  
CB8  
CB8  
CB8  
CB8  
NJHN  
250A  
208-240V  
100K  
100K  
100K  
100K  
MERLIN  
GERIN  
NJHN  
PJD  
400A  
600A  
800A  
208-240V  
208-240V  
208-240V  
MERLIN  
GERIN  
MERLIN  
GERIN  
PJD  
Table 11  
Non-automatic breaker schedule, 250-800A  
Circuit Breakers  
STS2/PDU  
Rating  
(See One-Line  
Diagrams)  
Withstand  
Current  
Vendor  
Type  
Ampacity  
Voltage  
208-240V  
380-480V  
208-240V  
380-480V  
100K  
65K  
CB1, CB2, CB3  
CB3A, CB4, CB5  
MERLIN  
GERIN  
250A  
400A  
NFHN  
NJHN  
250A  
100K  
100K  
CB1, CB2, CB3  
CB3A, CB4, CB5  
MERLIN  
GERIN  
400A  
CB1, CB2, CB3  
CB3A, CB4, CB5  
MERLIN  
GERIN  
600A  
800A  
NJHN  
PJD  
600A  
208-240V  
208-240V  
100K  
100K  
CB1, CB2, CB3  
CB3A, CB4, CB5  
MERLIN  
GERIN  
1000A  
68  
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Introduction to STS2/PDU Operations  
8.0 INTRODUCTION TO STS2/PDU OPERATIONS  
8.1 System Description  
A STS2/PDU provides an automatic, seamless transfer between input power sources to an output  
load. The STS2/PDU monitors the input sources, to ensure each source is operating within set param-  
eters, as well as ensure that each source is within acceptable tolerances for a transfer between  
sources to be completed.  
The STS2/PDU contains two static transfer switches in one enclosure to allow the unit to transfer its  
load between the two input sources without disruption to the output for longer than 1/4 of a cycle.  
If a problem is detected with a primary (Preferred) input source and defined trigger points are  
reached, the STS2/PDU automatically switches the input to the other (Alternate) input source. The  
STS2/PDU continues to monitor both sources and can automatically transfer the load back to the pre-  
ferred source, if so configured, when that source returns to acceptable operating parameters.  
The system control logic automatically monitors the input sources and power output to ensure that  
they are operating within acceptable tolerances. The system logic manages the transfer between  
sources.  
The STS2/PDU front panel contains a Color Graphical Display on an LCD touch screen display. The  
Color Graphical Display provides a menu-driven operator interface and a display of system informa-  
tion, status information, a one-line diagram (Mimic) of the STS2/PDU, active alarms and alarm his-  
tory information.  
The menu selections provide control of the preferred source, manual transfer initiation. Buttons pro-  
vide for audible alarm silence and reset.  
Through the touch screen, specific voltage, current and environmental parameters can be configured  
to trigger events that can sound an alarm, write to a history log and either transfer sources or inhibit  
a transfer.  
Preferred input source selection, alarm reset and alarm silencing are done through buttons on the  
touch screen display.  
Communication options provide external communication with the STS2/PDU through a modem, a  
network card, a programmable relay board, a contact isolator or an RS-422 port to Liebert’s SiteScan.  
8.1.1 Redundancy  
Redundancy within the STS2/PDU prevents one component from being a single point of failure,  
should a problem occur. Redundant circuits and components are used to eliminate single points of  
failure.  
Since the STS2/PDU has two input sources, no single component failure can cause a loss of power to  
the load. Redundant power supplies are provided which feed a DC dual-bus used throughout the unit  
to prevent any single-point power supply failure modes.  
Three separate redundant control logic modules are built into the system. Each contains the logic nec-  
essary to run the STS2/PDU and control all transfers.  
Redundant fans are provided if a primary fan fails. The redundant fans turn on to prevent overheat-  
ing inside of the unit.  
Should the front panel interface fail, the control logic continues to operate and the unit would transfer  
should a problem be detected on the preferred source. Information on the monitoring parameters  
would be available through the remote communication options, if available, or the DB9 (RS-232) con-  
nector located next to the LCD behind the front door. See Figure 55 for details.  
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Introduction to STS2/PDU Operations  
8.1.2 Reliability and Agency Requirements  
The STS2/PDU is designed for high reliability and high availability with a critical bus Mean Time  
Between Failure (MTBF) exceeding 1,000,000 hours.  
The STS2/PDU and all its options are designed, tested and certified, where applicable, to meet agency  
requirements as follows:  
• UL 891: Standard for Switchboard, for UL and ULc listing  
• UL 1008: Standard for Automatic Transfer Switches  
• UL 67: Standard for Panelboard  
• UL 1561: Standard for Dry Transformers  
• UL 1459: Telephone equipment (Modem)  
• NEC  
• FCC Part 15 EMI emission limits for Class A computing devices.  
The STS2/PDU uses conservatively rated components, minimizing the need to go to maintenance  
bypass. All normal maintenance and repair work can be done through the front panel of the unit. This  
access makes repairs and maintenance easier.  
Gating and control logic are partitioned so that failure of one source’s gating or sensing logic does not  
prevent the switch from transferring to the other source.  
All control and logic components are mounted separate from the power components. The STS2/PDU is  
designed to minimize the exposure of hazardous voltages to allow safe servicing of the unit while the  
load is energized.  
All electrical components requiring normal maintenance are replaceable without de-energizing the  
load, as long as one source is available. Solid-state switching devices are packaged to allow safe repair  
of those devices without having to de-energize the load. All non-automatic switches or circuit breakers  
are the plug-in or draw-out type to allow replacement without de-energizing the load. All other com-  
ponents, including transformers, power cables and connections, circuit breaker bases, etc., are  
replaceable from the front, rear or top of the unit—however, this requires all power to be removed  
from the unit for safety. All solid-state power switching devices are rated to prevent hazardous device  
failure in power systems with available fault currents up to the defined limits, as listed in 14.1.6 -  
8.1.3 Factory Backup and Service Assistance  
Because improper installation can cause a system to fail, a Liebert Global Services or a factory  
trained service technician should thoroughly inspect the unit to ensure it is properly installed and its  
operating parameters are properly configured.  
Once the STS2/PDU is properly installed, you, as the on-site operator, can easily monitor the unit’s  
operation utilizing the touch screen.  
In the United States, if you need assistance or have questions, call 1-800-LIEBERT (1-800-543-2378).  
Outside the 48 contiguous United States, contact Liebert Global Services, if available in your area.  
For international areas not covered by Liebert Global Services, the Liebert authorized distributor can  
provide technical support.  
8.2  
Modes of Operation  
8.2.1 Normal (Preferred Source)  
Under normal operating conditions, the STS2/PDU routes power from the preferred input source to  
the output load. The unit monitors the voltage current and phase of each source to ensure that both  
are operating within set tolerances and that the alternate source is available, should a transfer be  
required.  
70  
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Introduction to STS2/PDU Operations  
8.2.2 Transfer  
Should the preferred source fail or be outside acceptable voltage limits, the STS2/PDU transfers the  
input to the alternate source until the problem is rectified in the preferred source. The unit can be set  
to automatically transfer the input back to the preferred source or allow the transfer to be done only  
manually.  
8.2.3 Transfer Inhibit  
For a transfer to be completed between input sources, the sources must meet certain parameters or  
the transfer cannot take place. Uninterrupted transfer between sources is inhibited due to input  
source failure, sources out of sync, switch failure or the unit is in bypass mode.  
8.2.4 Bypass  
The Static Transfer Switch 2 Power Distribution Unit can be manually bypassed to allow the power  
from a source to directly flow to the output load. This bypass allows the unit’s electronics to be ser-  
viced without dangerous voltages being present.  
The STS2/PDU includes key-interlocked maintenance bypass breakers that allow either input  
source’s electronics to be bypassed for maintenance without interruption of power to the load. The  
maintenance bypass allows all electronics to be isolated from the input, output and bypass connec-  
tions. Bypass instructions are available from the touch screen and are discussed later in this manual.  
8.3  
Operator Controls  
The STS2/PDU is equipped with an interface to configure and monitor the unit either locally or  
remotely. The Color Graphical Display is a touch screen LCD that provides a color diagram (Mimic)  
that displays the current status of the unit. System parameters are displayed and help is available to  
define events. See Figure 58 below and Figure 57 in 7.0 - Installation Drawings. The touch  
screen menus allow the operator to initiate source transfers, view event and history logs and view  
bypass and other operational instructions.  
Figure 58 STS2/PDU touch screen display  
Mimic  
Event controls  
Display panel  
and help  
screen  
Event display  
Menu options  
Touch screen control buttons allow you to reset alarms, silence the audible alarm, review configura-  
tions, event and history logs, preferred source, startup and bypass procedures and the help menu.  
Qualified personnel, with a password, can use these menus to configure parameters, select a pre-  
ferred source and do manual source transfers.  
Units can be accessed from a terminal or a PC running terminal emulation software attached to the  
unit. Through the RS-232 access, you can monitor and configure the unit, plus remotely select a pre-  
ferred source. See 12.1 - Using the RS-232 Port for instructions on using the RS-232 interface.  
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Theory of Operation  
9.0 THEORY OF OPERATION  
9.1 General Description  
The STS2/PDU contains all the equipment necessary to prevent an interruption in power flow to the  
AC load, should your primary source fail.  
9.1.1 Static Transfer Switch 2 Power Distribution Unit  
The STS2/PDU is a combination automatic static transfer switch and power distribution unit. The  
STS2/PDU shall include two isolation transformers connected to a solid-state, three-pole, dual-posi-  
tion static transfer switch designed to automatically and manually switch between two synchronized  
three-phase AC power sources without an interruption of power to the load longer than 4 milliseconds  
(1/4 cycle). Input, output, bypass circuit breakers and a distribution section shall be included to form  
an integrated system in a single freestanding enclosure.  
The preferred source is the input source that normally carries the load when both sources are avail-  
able. The preferred source is selectable by the user from the LCD panel or an optional Remote Source  
Selection. The unselected source is referred to as the alternate source and carries the load if the pre-  
ferred source should fail or if a manual transfer is initiated.  
The unit uses Silicon Controlled Rectifiers (SCRs) connected in paralleled, opposing pairs to function  
as an AC switch configuration. Three pairs of SCRs connect the AC load to the selected preferred  
input source as long as the preferred source is available. A second set of SCRs stands ready to trans-  
fer the AC load to the alternate input source should the preferred source fail. The switching action is  
a very fast, break-before-make with less than a 1/4 cycle break in the AC waveform.  
During static switch transfers and retransfers, the conduction state of the SCRs is carefully moni-  
tored and controlled to prevent a current path from one source to the other. This technique prevents a  
faulted source from feeding into the other good source.  
9.1.2 Source Transfer  
The STS2/PDU allows manually initiated transfers between the two sources, providing the alternate  
source is within acceptable voltage limits and phase tolerances with the preferred source. You begin a  
manual transfer by selecting the inactive source as the preferred source. On a manual transfer, the  
STS2/PDU transfers between the two sources with less than one (1) millisecond interruption of power  
to the load. The transfer can only be completed when both sources are available and synchronized  
within the user-adjustable phase synchronization window. For sources where the two frequencies are  
not exactly in phase, manually-initiated transfers are delayed by the STS2/PDU until the two sources  
are within the defined phase synchronization window.  
Source selection can also be done remotely using the Remote Source Selection option, if installed.  
9.1.3 Automatic Transfer/Retransfer  
If the preferred source is out of voltage and/or frequency limits, the load is automatically transferred  
to the alternate source. The default transfer voltage limits comply with the limits of the  
IEEE Std. 446-1995 computer voltage tolerance envelope.  
If the unit is so configured, the load is retransferred automatically to the preferred source after the  
preferred source returns to within the acceptable voltage and frequency limits for at least the defined  
retransfer time delay and is in phase with the alternate source. You can enable and disable automatic  
retransfer to the preferred source through a user configuration setting.  
Automatic Retransfer Inhibited  
If the system makes five transfers from the preferred source to the alternate source in a five minute  
period, automatic retransfers back to the preferred source is disabled.  
To clear this alarm condition, you must assign the alternate source as the preferred source. Also, the  
UV detection thresholds may need adjustment. See Source Setpoints on page 101 for instructions  
on setting the UV detection.  
This alarm also is cleared if the unit transfers to the preferred source due to an alternate source AC  
volt failure (i.e., an emergency transfer.)  
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Theory of Operation  
9.1.4 Emergency Transfer  
To ensure that power remains connected to the load, the STS2/PDU automatically performs an emer-  
gency transfer from one input source to the other when an outage occurs on the existing source.  
The automatic transfer takes place if the other source’s voltage is within acceptable limits and regard-  
less of the phase difference between the two sources.  
Emergency transfers occur with a loss of power on the output of less than 4 ms.  
Emergency transfers from the alternate source to the preferred source are not affected by the Auto  
Retransfer Enabled/Disabled or Retransfer Delay user settings.  
9.1.5 Load Current Transfer Inhibit  
The STS2/PDU senses the load current. If the load current exceeds the preset level deemed to repre-  
sent a load inrush or fault condition, the unit’s logic disables manual and automatic transfers, even if  
the selected source’s input voltage is outside the acceptable limits. This event triggers an I-Peak  
alarm. If so configured, the Load Current Transfer Inhibit is automatically reset after the current and  
voltage return to within normal parameters. This reset provides continued protection against a  
source failure. The Load Current Transfer Inhibit also can be programmed to require a manual reset.  
9.1.6 SCR Failure  
The STS2/PDU continuously monitors the status of the SCR switching devices for proper operation.  
In the event of a shorted SCR on the input source powering the load, the STS2/PDU automatically  
triggers an alarm and trips open the other source isolation breaker. In the event of a shorted SCR on  
the other input source, the STS2/PDU automatically triggers an alarm and trips open the other  
source isolation breaker.  
In the event of an open SCR, the switch automatically triggers an alarm and transfers the load to the  
other source. All open and shorted SCR alarm conditions are latched and require the system to be  
repaired and reset to restore normal operation.  
9.1.7 On/Off Sequence  
The STS2/PDU contains no master On/Off push button control. When connected to the input sources,  
the unit’s logic power comes on automatically. The touch screen display is active as long as at least  
one input source is energized and the Control Power Disconnect (located inside the static switch) is  
closed.  
9.2  
Detailed Component Description  
9.2.1 Controls  
Operator Interface  
The STS2/PDU Color Graphical Display unit contains a touch screen color LCD to provide the opera-  
tor interface to control and configure the operation of the unit and quickly diagnose problems. A pass-  
word and an optional keylock, if installed, are provided for security.  
Hardware  
• The STS2/PDU operator interface in the Color Graphical Display unit is designed to provide all of  
the information required to configure and monitor the unit’s operation.  
• The control logic performs automatic operations with minimal operator interface.  
• Each STS2/PDU unit is equipped with a color LCD touch screen.  
• The STS2/PDU can have optional communication ports installed. See 6.0 - Options and 12.0 -  
Communication Interfaces for more information on communication options.  
• The RS-232 interface is used for configuration and status and event log monitoring.  
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Theory of Operation  
Firmware  
The operator interface enables you to monitor the STS2/PDU, to configure setpoints for transfers,  
monitor system parameters and access event and history logs. The firmware is accessible through the  
LCD touch screen or the RS-232 interface. The firmware includes:  
• View and set the preferred source.  
• View and configure setpoints.  
• View alarms, faults and status.  
• The mimic graphical representation of the systems operation.  
• Menu driven monitoring and configuration.  
• Step-by-step instructions to assist you in the start-up, shut-down and bypass operations.  
• Help on event messages.  
• Touch screen alarm reset and silence buttons.  
Events in the system, both faults and alarms, are detected and displayed on the LCD. See 11.0 -  
Alarms and Faults for more information on events.  
• A set of event masks can be configured through the LCD to trigger a system response to an event.  
• Report event conditions from other components of the system.  
• Monitor and report changes in event condition states. If the event condition’s state changes from  
inactive to active, a new event is detected. If the transition is from active to inactive, the event  
condition has cleared.  
• Process new faults and alarms and clear inactive alarms.  
• Provide the alarm reset and silence options.  
9.2.2 Circuit Breakers and Non-Automatic Circuit Breakers  
Input circuit breaker for each source provides over current protection for the STS2/PDU. Three non-  
automatic circuit breakers provide total isolation of the solid-state switching devices with an input  
non-automatic breaker for each source and a load isolation non-automatic breaker. Two non-automatic  
breakers provide for maintenance bypassing of the solid-state switching devices to either input source.  
All breakers in the STS2/PDU are plug-in types, which allows any breaker to be replaced without de-  
energizing the output bus. The breakers have an interlock in the plug-in base, which prevents the  
switch from being withdrawn in the CLOSED position. The switch trips OPEN before it disconnects  
from the plug-in base.  
See 14.2.5 - Circuit Breakers for specifications and more information pertaining to the circuit  
breakers. See Figures 23 through 36 for circuit breaker locations.  
The circuit breaker schedule is provided in Tables 9 through 11.  
9.2.3 SCRs  
Brick-type SCRs are used rated to carry the full 100% rated load. The unit is a fuseless design with  
input circuit breakers providing overcurrent protection.  
9.2.4 Logic Modules  
The logic contains three separate redundant logic modules. The modules contain the logic necessary  
to run the STS2/PDU and control transfers and shunt trips under all circumstances, without any out-  
side assistance once set-up and started properly.  
9.2.5 Audible Alarm  
An audible alarm is installed on the control board. This alarm is triggered by an alarm condition  
detected on the unit. The alarm can be turned off from the touch screen. Turning off the audible alarm  
does not clear or reset the condition that triggered the alarm.  
9.2.6 RS-232 Port  
An RS-232 serial port is provided to allow an external terminal to be connected as another user inter-  
face. See 12.1 - Using the RS-232 Port for more information.  
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Operating Instructions  
10.0 OPERATING INSTRUCTIONS  
CAUTION  
!
Before unit is placed into service for the first time, after equipment relocation or after the  
equipment has been de-energized for an extended period, a thorough equipment inspection  
and supervised start-up by qualified personnel are strongly recommended. Contact your local  
Liebert representative or Liebert Global Services at 1-800-543-2378 to arrange for equipment  
inspection and start-up.  
After the initial equipment start-up, the following operating guidelines can be used for standard equip-  
ment operation. These guidelines should be reviewed for any special equipment modifications, special  
site conditions or company policies that may require changes to the standard equipment operation.  
All programmable functions are preset at the factory to enable the unit to be brought up without the  
need to enter all selectable parameters.  
The LCD touch screen is discussed in more detail in 13.0 - Touch Screen Display.  
See Figures 23 through 36 for circuit breaker locations.  
10.1 Normal System Turn-On  
1. Depending on the type of distribution used:  
• If equipped with output breaker CB8, open CB8.  
• If equipped with output inline panelboards, open panelboard main breakers CB8 and CB9  
and, if supplied, CB10 and CB11.  
• If optional subfeed breakers are supplied, open subfeed breakers CB12 and CB13.  
See Figures 3 through 6 for location of breakers.  
a. Retract the bolts on the key interlocks for CB1 and CB2.  
b. Extend the bolts on the key interlocks for CB4 and CB5, thus preventing CB4 or CB5 from  
being turned ON.  
2. Apply source/input power to both STS2/PDU inputs by closing CB6 and CB7.  
The touch screen control panel should become active and operate properly when at least one of the  
inputs is energized.  
3. Verify that nominal input voltages are applied to both inputs (Source 1 and Source 2).  
The input voltages, selected preferred source, breaker and switch status and alarms are indicated  
on the Mimic screen.  
Figure 59 STS2/PDU touch screen display  
Mimic  
Sources  
Static  
Transfer  
Switch  
Event controls  
Event display  
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Operating Instructions  
4. Close CB1.  
5. Verify that Source 1 voltages are nominal and that CB1 breaker status is correctly indicated on  
the Monitor/Mimic screen.  
6. Close CB2.  
7. Verify that Source 2 voltages are nominal and that CB2 breaker status is correctly indicated on  
the Mimic screen.  
8. Verify that boxes for the preferred source and corresponding Static Transfer Switch 2 Power  
Distribution Unit are highlighted on the Mimic screen, indicating which side of the Static  
Transfer Switch 2 Power Distribution Unit is on.  
9. Close Output Breaker CB3 (for redundant output configurations, also close CB3A).  
10. Verify that CB3, the Output box and the Load box are highlighted, indicating that CB3 is closed  
and the STS output is energized. On units with I-line panelboard, the panelboard is also  
energized.  
NOTE  
For redundant output configurations, CB3 descriptions apply to CB3 and CB3A.  
11. Press the RESET button on the touch screen to reset any previous alarms.  
12. Check the Event Display and the Mimic to verify there are no active alarms. If any active alarms  
are displayed, refer to 11.0 - Alarms and Faults for a description of the alarms and possible  
causes. Correct all active alarm conditions before proceeding.  
13. If unit is equipped with output breaker CB8, close CB8. The output and load are energized.  
14. If unit is equipped with output inline panelboards, close panelboard main breakers CB8 and CB9  
and, if supplied, CB10 and CB11. Turn on panelboard breakers. If optional subfeed breakers are  
supplied, close subfeed breakers CB12 and CB13.  
15. Turn on the load equipment as directed in the load equipment manufacturer’s recommendations.  
10.2 Manual Transfer / Preferred Source Selection  
The Source Transfer option (Source Xfers) in the touch screen menu allows you to select a preferred  
source. Transfers are only permitted when the voltage and current are within their proper operating  
range and the sources are synchronized. The Source Transfer screen indicates the synchronization  
between the two sources, while the voltage and frequency are displayed on the Mimic. See Figure 60.  
Transfer is inhibited if the deviation exceeds the parameter set in Source Setpoints. See User  
NOTE  
If one source will be de-energized for an extended period (hours or days), set the STS2/PDU to  
bypass mode for the remaining source. Without using bypass, if a failure occurs in the switch  
components for the remaining source, the STS2/PDU does not have a second source to switch  
to and the load would not receive power. See 14.2.12 - Maintenance Bypass for bypass  
instructions.  
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Operating Instructions  
Figure 60 Source Transfer screen  
To manually select the preferred source:  
1. Close the input breakers CB6, CB7, CB1 and CB2.  
2. Select SOURCE XFERS from the menu bar.  
The Select Preferred Source screen is displayed in the Event Display.  
3. Check the Mimic to verify that Source 1 and Source 2 input voltages are correct.  
4. Select SOURCE 1 or SOURCE 2 as your preferred source.  
This source is now monitored as the preferred source throughout the various configurations set up  
through the touch screen.  
5. Verify that the correct source is designated as the preferred source and that the input source  
changes to the desired source.  
The Mimic is updated to indicate the new preferred source. The source is now highlighted with blue  
and that source is labeled as the preferred source.  
If the Transfer Inhibit message is displayed, check for alarm messages on the Active Status window.  
Correct alarm conditions before attempting a source transfer.  
NOTE  
The preferred source may also be changed via the optional Remote Source Selection option,  
thereby initiating a transfer remotely  
10.3 Enabling Remote Source Selection  
If your system is equipped with the optional Remote Source Selection option, it must be enabled.  
From the Color Graphical Display:  
1. Select CONFIG from the menu bar.  
2. Select SYSTEM SETTINGS from the Configuration menu.  
3. Select SYSTEM OPTIONS from the System Settings menu.  
4. Select YES for the REMOTE SOURCE SELECT choice.  
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Operating Instructions  
10.4 Maintenance Bypass  
The STS2/PDU is equipped with two key-interlocked, bypass breakers, CB4 and CB5, to allow man-  
ual bypass of the switch electronics for either input source in the event of switch failure or for mainte-  
nance of the switch. Refer to Figure 3. While operating on maintenance bypass, all voltages are  
removed from the static transfer switch electronics to facilitate safe repair, without de-energizing the  
load using a make-before-break switching sequence.  
However, the unit can be bypassed using a make-before-break switching sequence only to the same  
source to which that the switch is connected, as indicated by the highlighted static transfer switch box  
on the Mimic screen.  
In the event of source or switch failure, the unit should be bypassed only to the current input source.  
For convenience, instructions for the bypass procedure can be displayed on the touch screen by select-  
ing the BYP. PROC option from the menu bar.  
The Mimic is used to verify the status of the unit during the bypass procedures. In the unlikely event  
that the Color Graphical Display is not available, open the front door and look through the slots in the  
control door. If you can see green LEDs on the gate driver board through that slot, then the unit is  
connected to the source referenced on the label below that slot. See Figure 61.  
Figure 61 Gate board viewing slot locations  
Touch Screen  
Viewing Slot  
for the Source 2  
Viewing Slot  
for the Source 1  
Gate Drive Board  
Gate Drive Board  
Green LEDS on the  
Gate Driver Board  
are viewable through  
this slot indicate that  
the STS is on  
Source 1  
GREEN LEDS ON  
THE GATE DRIVER  
BOARD ARE VIEW-  
GREEN LEDS ON  
THE GATE DRIVER  
BOARD ARE VIEW-  
ABLE  
THROUGH  
ABLE  
THROUGH  
THIS SLOT INDI-  
CATE THAT THE STS  
IS ON SOURCE 2  
THIS SLOT INDICATE  
THAT THE STS IS ON  
SOURCE 1  
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Operating Instructions  
10.4.1 Bypass Procedures for Source 1  
To bypass the switch for Source 1:  
NOTE  
If you wish to bypass the Source 1 static transfer switch but Source 2 is presently active, you must first  
1. Verify Source 1 is supplying power via the Mimic.  
• If the Color Graphical Display is not available, check the gate driver board LEDs through the  
slots in the control panel. See Figure 61.  
2. Remove interlock key from CB5 and place it in the CB4 interlock.  
3. Open the alternate source input breaker CB2.  
4. Rotate and remove the interlock key.  
5. Insert the key in the CB4 bypass breaker interlock.  
6. Rotate interlock keys in CB4 bypass breaker interlock to retract interlock.  
7. Close bypass breaker CB4.  
8. Verify the breaker status on the Mimic screen.  
9. Open source input breaker CB1.  
10. Rotate the interlock key and remove it to lockout the breaker.  
11. Secure the key, per your site’s lockout/tagout procedure.  
12. Open output breakers CB3 and CB3A (if supplied) to remove power from static switch.  
To return to the normal mode:  
1. Remove the key from CB5 and insert it in the CB1 breaker interlock.  
2. Rotate key to retract interlock.  
3. Close source input breaker CB1.  
4. Verify the Source 1 and CB1 breaker status on the Mimic screen.  
5. Close output breakers CB3 and CB3A (if supplied).  
6. Verify CB3 and CB3A breaker status and STS SOURCE 1 and OUTPUT boxes are highlighted on  
the Mimic screen.  
7. Open bypass breaker CB4.  
8. Rotate the keys in CB4 interlock to extend the interlock.  
9. Remove the proper key from CB4 interlock and insert it into CB2 breaker interlock.  
10. Rotate the key to retract the CB2 breaker interlock.  
11. Close source input breaker CB2.  
12. Verify the STS SOURCE 2 box and CB2 breaker status on the Mimic screen.  
• If the Color Graphical Display is not available, check the gate driver board LEDs through the  
slots in the control panel. See Figure 61.  
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Operating Instructions  
10.4.2 Bypass Procedures for Source 2  
To bypass the switch for Source 2:  
NOTE  
If you wish to bypass the Source 2 static transfer switch but Source 1 is presently active, you must first  
1. Verify Source 2 is supplying power via the Mimic.  
• If the Color Graphical Display is not available, check the gate driver board LEDs through the  
slots in the control panel. See Figure 61.  
2. Remove the interlock key from CB4 and place it in CB5 interlock.  
3. Open the alternate source input breaker CB1.  
4. Rotate and remove the interlock key.  
5. Insert the key in the CB5 bypass breaker interlock.  
6. Rotate interlock keys in the CB5 bypass breaker interlock to retract the interlock.  
7. Close bypass breaker CB5.  
8. Verify the breaker status on the Mimic screen.  
9. Open source input breaker CB2.  
10. Rotate the interlock key and remove it to lockout the breaker.  
11. Secure the key, per your site’s lockout/tagout procedure.  
12. Open output breakers CB3 and CB3A (if supplied) to remove power from static switch.  
To return to normal mode:  
1. Insert the key in the CB2 breaker interlock.  
2. Rotate the key to retract the interlock.  
3. Close source input breaker CB2.  
4. Verify Source 2 and CB2 breaker status on the Mimic screen.  
5. Close output breakers CB3 and CB3A (if supplied).  
6. Verify CB3 and CB3A breaker status and STS SOURCE 2 and OUTPUT boxes are highlighted on  
the Mimic screen.  
7. Open bypass breaker CB5.  
8. Rotate the keys in CB5 interlock to extend the interlock.  
9. Remove the proper key from CB5 interlock and insert it into CB1 breaker interlock.  
10. Rotate the key to retract the CB1 breaker interlock.  
11. Close source input breaker CB1.  
12. Verify the STS SOURCE 1 box and CB1 breaker status on the Mimic screen.  
• If the Color Graphical Display is not available, check the gate driver board LEDs through the  
slots in the control panel. See Figure 61.  
10.5 Normal System Shutdown  
The STS2/PDU can be shut down from either the static switch mode or the bypass mode.  
10.5.1 Shutdown in Static Transfer Switch Mode  
When the STS2/PDU is operating on static transfer switch mode (not maintenance bypass mode):  
1. Turn off the load equipment per manufacturer’s recommendations.  
2. Open CB8 or panelboard breakers and mains if supplied  
3. Open CB3 to turn off the static switch output.  
• Open CB3A if the Static Transfer Switch 2 Power Distribution Unit has a redundant output  
configuration.  
4. Open the input switches CB1 and CB2.  
5. To completely de-energize the unit, open CB6 and CB7.  
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Operating Instructions  
10.5.2 Shutdown in Maintenance Bypass Mode  
When the Static Transfer Switch 2 Power Distribution Unit is operating on bypass:  
1. Turn off the load equipment per manufacturer’s recommendations.  
2. Open CB8 or panelboard breakers and main if supplied  
3. Open the bypass switch (CB4 or CB5) to turn off the static transfer switch output.  
4. To completely de-energize the unit, turn open CB6 and CB7.  
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Alarms and Faults  
11.0 ALARMS AND FAULTS  
Alarms and faults are events that are triggered when the operation of the Static Transfer Switch 2  
Power Distribution Unit falls outside of the defined parameters. These events can also be triggered  
by: user actions, such as changing configurations, clearing logs, etc.; failed components such as a fan  
failure, an SCR that is open or shorted, etc.; and system status, such as open circuit breakers, load on  
alternate source, etc. These events can provide a warning or trigger the system to make a change,  
such as switch sources or the recording of a history log.  
The STS2/PDU monitoring system detects and annunciates a comprehensive set of fault and alarm  
conditions. Faults and alarm messages are can be viewed on the LCD touch screen or via the RS-232  
port.  
On the LCD touch screen, the events are shown in the Status Display panel in the lower left corner of  
the touch screen and written to the Event log. You can touch a message to view a definition of an  
event and a tip for troubleshooting. See 13.0 - Touch Screen Display for more information about  
the touch screen.  
If you are monitoring the system through the RS-232 port, see Table 13 for the commands to view  
event logs and alarm and fault lists.  
Event actions can be triggered by the settings configured from the Event Masks. See 11.1 - Event  
Mask for more information.  
Faults — A fault indicates that a component of the STS2/PDU has failed or has been damaged. In the  
Event Display, faults are indicated in red.  
Alarms — An alarm is an event caused by a significant abnormal system condition. In the Event Dis-  
play, alarms are indicated in yellow. The setpoints for many of the alarms are configurable through  
the User Settings. Many alarms clear themselves when the condition is resolved. If an alarm event  
mask is set to latch, the alarm messages remain active until the alarm condition has been corrected  
and the RESET button is pushed. See 11.1 - Event Mask for more information on latching.  
When the system is furnished with an optional internal or external modem and a telephone line is  
connected to the modem, the system can be programmed to automatically dial out upon occurrence of  
any of certain designated alarms. The auto-dial feature can be configured for alarms using the Event  
Mask option in the touch screen. See Configuring the Modem on page 105 for instructions on for  
setting up your modem.  
11.1 Event Mask  
The STS2/PDU gathers, processes and reports faults and alarms, collectively referred to below as  
events. The Event Mask dialog box allows you to set the system’s response for specific alarms and  
faults that are generated.  
The following mask types are available for each event:  
• Latch — If a latch is enabled for the selected event, that event remains active even if the originat-  
ing event condition clears. A latched event may only be cleared by pushing the RESET button.  
• Dial Out — If the selected event is triggered, the system automatically calls the specified tele-  
phone numbers through the modem. For example, a page could be sent or an event could be sent  
to a external terminal, via the modem. See 12.0 - Communication Interfaces for more informa-  
tion on configuring communications options.  
• Event Log — The selected event is date/time stamped and recorded to the Event Log when the  
event is triggered.  
• Audible — If the selected event is triggered, an audible beeper or horn is sounded by the  
STS2/PDU. The beeper continues while this event is active or latched or until the SILENCE but-  
ton is pushed.  
See Event Masks on page 100 for instructions on setting the mask type via the touch screen dis-  
play. See the 12.1.4 - Setting Event Masks with the Terminal for instructions on configuration  
using the RS-232 port.  
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Alarms and Faults  
11.2 Event and History Logs  
The system tracks events through the Events Log and tracks significant events through the History  
Logs. These logs allow you to quickly spot trends or diagnose problems that the unit may have had.  
Both logs are written in nonvolatile memory.  
The logs can be accessed from the touch screen menu or the RS-232 port. See 13.7.1 - Logs for more  
instructions on viewing the logs from the touch screen. See Table 13 for the RS-232 interface com-  
mands used to access the logs.  
11.2.1 Event Log  
The events are tracked in sequence of occurrence. The sequence of occurrence is identified by date,  
time and frame number. The last 512 events are stored in a nonvolatile memory and can be viewed  
from the Event Log.  
Event logs wrap, meaning when the log is full, the oldest event is deleted when a new event is written  
to the log.  
The Event Log tracks:  
• # — the sequence number in which the event occurred since the log was last cleared.  
• Message — the event that occurred, such as Ambient Over temp., Source 1 Fail, etc.  
• Type — either a Fault or Alarm. See 11.0 - Alarms and Faults for further details on these  
events.  
• ID — the event identifier.  
• Date and Time — when the event occurred.  
• Faults — the number of fault events logged.  
• Alarms — the number of alarm events logged.  
• User Alarms — the number of alarm events logged that were triggered by user-created alarms,  
such as those alarms created with the Input Contact Isolator settings.  
• Total — the sum of all the events currently logged.  
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Alarms and Faults  
11.2.2 History Log  
When a designated major alarm occurs, the History Status buffer is frozen, capturing 64 sequential frames  
before and after the alarm condition. When the History Status buffer is frozen, a History Log is created.  
Two History Logs are available to track major alarms. This log includes the triggering event plus the  
surrounding events and the system voltages, currents, frequency, power, source selection and breaker  
positions at the time of the event. The History Log displays the 64 sequential frames, in 4-millisecond  
intervals, of the Present Status screens surrounding the event.  
If you are viewing the log from the touch screen, the Mimic and the Event Display show the data that  
was present as the alarm was triggered. The data is displayed as frames are played.  
The History Log allows you to replay the events leading up to the alarm and the events right after the  
alarm to see the status of the switch at that time and diagnose the cause of the alarm. The History  
Log is triggered when certain events are tripped that have the Freeze option enabled.  
You can run through the frames sequentially. The sequence of the events is identified by date, time  
and frame number. The History Log frames are stored in a nonvolatile memory buffer that is continu-  
ously overwritten until a designated fault condition occurs. When the fault occurs to trigger a freeze,  
the History Log stores the next 23 frames, then freezes until it is reset. The History Log then keeps 40  
frames before the fault, the frame where the fault occurred, plus the next 23 frames.  
The History Log should not be reset until the fault condition that caused the buffer to freeze is  
reviewed and investigated by a qualified service technician. After the alarm condition has been cor-  
rected, the History Log can be cleared.  
The History Log has the following fields:  
• Replay Rate — indicates how long it takes for the replay to play. Use the UP and DOWN buttons  
to set the time.  
• Status — the status of the STS2/PDU at the point of the current frame in the replay. The History  
log has three statuses: Frozen, Not Frozen and Retrieving Data, please stand by.  
• Critical Event — The event which triggered this log to be written. The event is indicated in red on  
the bar graph.  
• Frame Number — the current frame in the replay. A negative number indicates the replay is at a  
point before the triggering event occurred.  
11.3 Alarm Notes  
The I-PK on Source 1 and I-PK on Source 2 alarms inhibit automatic transfer due to an overload or  
load fault. These alarms can be set for either auto or manual alarm reset.  
In the auto reset mode, the alarm is reset as soon as the load current and source voltage return to are  
inhibited until the conditions return to normal and the user manually presses the RESET button. In  
either case, the cause of the Source 1 or Source 2 Ipeak overload should be investigated and resolved  
(such as by reducing the overload condition or clearing the output fault) before returning the switch to  
normal operation.  
These events indicate a device failure. The device must be replaced and the system must be restarted  
for the fault to clear. A shorted SCR automatically trips open a source input switch (CB1 or CB2) to pre-  
vent transfers in the event of an SCR failure. The SCR failure must be investigated and repaired before  
returning the switch to normal operation. Both source input switches must be opened (such as when  
the unit is placed in maintenance bypass for servicing) before a shorted or open SCR alarm can be reset.  
11.4 List of Messages  
Table 12 lists available event messages, a definition of the event and the functions that are activated  
with the event by default. The functions are indicated as follows:  
D — The indicated event initiates the Auto-Dial sequence through the optional modem.  
A — The indicated event activates the Audible alarm.  
F — The indicated event triggers a Freeze of the History Log.  
L — The indicated event Latches. A latched alarm remains displayed until the alarm condition  
has cleared and the RESET button has been pressed.  
E — By default, all faults and alarms are written to the Event Log. See 12.1.4 - Setting Event  
All of these functions, except Freeze, can be reconfigured to trigger for each event, using the Event Mask  
option. See 11.1 - Event Mask. The Freeze function is hard-coded and cannot be changed for a event.  
84  
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Alarms and Faults  
Table 12 Event messages  
ID  
1
Alarm Message  
S1 SCR SHORT  
Description/Cause  
Action  
One or more of the SCRs for Source 1 have shorted and failed.  
One or more of the SCRs for Source 2 have shorted and failed.  
One or more of the SCRs for Source 1 is open.  
D, F, A, E  
D, F, A, E  
D, F, A, E  
D, F, A, E  
2
S2 SCR SHORT  
S1 SCR OPEN  
S2 SCR OPEN  
3
4
One or more of the SCRs for Source 2 is open.  
A primary cooling fan has failed and the unit is now being cooled by a  
secondary fan, which is not monitored.  
5
PRIMARY FAN FAIL  
D, A, E  
6
CONTROL MODULE FAIL  
PWR SPLY DC A FAIL  
PWR SPLY DC B FAIL  
PWR SPLY S1 AC FAIL  
PWR SPLY S2 AC FAIL  
PWR SPLY LOGIC FAIL  
OUT VOLT SENSE FAIL  
S1 VOLT SENSE FAIL  
S2 VOLT SENSE FAIL  
S1 SCR SENSE FAIL  
S2 SCR SENSE FAIL  
S1 CURR SENSE FAIL  
S2 CURR SENSE FAIL  
S1 GATE DRIVE FAIL  
S2 GATE DRIVE FAIL  
INTERNAL COMM FAIL  
CB1 SHUNT TRIP FAIL  
CB2 SHUNT TRIP FAIL  
EQUIPMENT FAN FAIL  
INPUT 1 SURGE FAIL  
INPUT 2 SURGE FAIL  
HEATSINK OVERTEMP  
EQUIPMENT OVERTEMP  
S1 UV  
Control logic module has failed.  
Power supply DC bus A has failed.  
Power supply DC bus B has failed.  
Power supply Source 1 AC has failed.  
Power supply Source 2 AC has failed.  
A power supply module has failed.  
The output volt sense module failed  
The Source 1 volt sense module failed.  
The Source 2 volt sense module failed.  
The Source 1 SCR sense module failed.  
The Source 2 SCR sense module failed.  
The Source 1 SCR current module failed.  
The Source 2 SCR current module failed.  
The Source 1 gate drive module failed.  
The Source 2 gate drive module failed.  
Internal CAN communications failed.  
CB1 shunt trip failed.  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
D, A, E  
A, E  
7
8
9
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
23  
24  
27  
28  
29  
64  
65  
67  
68  
69  
70  
71  
72  
73  
74  
75  
76  
77  
78  
79  
80  
CB2 shunt trip failed.  
One of the equipment fans failed  
Source 1 input surge suppression module failed  
Source 2 input surge suppression module failed  
Heatsink has exceeded the recommended temperature.  
Cabinet has exceeded the recommended temperature  
Source 1 under voltage, fast detection.  
Source 1 under voltage, slow detection.  
Source 1 over voltage  
A, E  
A, E  
S1 UV (RMS)  
A, E  
S1 OV  
A, E  
S1 OF/UF  
Source 1 over frequency/under frequency  
Source 1 failure.  
A, E  
S1 FAIL  
A, E  
S2 UV  
Source 2 under voltage, fast detection.  
Source 2 under voltage, slow detection.  
Source 2 over voltage.  
A, E  
S2 UV (RMS)  
A, E  
S2 OV  
A, E  
S2 OF/UF  
Source 2 over frequency/under frequency.  
Source 2 failure.  
A, E  
S2 FAIL  
A, E  
S1 OVERCURRENT  
S2 OVERCURRENT  
S1 I-PEAK  
Source 1 over current.  
A, E  
Source 2 over current.  
A, E  
I-PK on Source 1.  
D, F, A, E  
D, F, A, E  
S2 I-PEAK  
I-PK on Source 2.  
85  
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Alarms and Faults  
Table 12 Event messages (continued)  
ID  
81  
82  
83  
84  
85  
86  
87  
88  
89  
90  
91  
92  
93  
Alarm Message  
SOURCES OUT OF SYNC  
LOAD ON ALT SOURCE  
AUTO REXFER INHIBIT  
CB1 (S1) OPEN  
Description/Cause  
Source 1 and Source 2 are out of synchronization.  
The output load is running on the alternate source.  
Automatic retransfer is inhibited.  
Action  
A, E  
A, E  
A, E  
Source 1, Circuit Breaker 1 is open.  
Source 2, Circuit Breaker 2 is open.  
Source 1 on bypass, Circuit Breaker 4 is closed.  
Source 2 on bypass, Circuit Breaker 5 is closed.  
Output circuit breaker (CB3) is open.  
Output circuit breaker (CB3A) is open.  
Source 1 phase rotation error.  
A, E  
CB2 (S2) OPEN  
A, E  
CB4 (S1 BYP) CLOSED  
CB5 (S2 BYP) CLOSED  
CB3 (OUTPUT) OPEN  
CB3A (OUTPUT) OPEN  
S1 PHASE ROT ERROR  
S2 PHASE ROT ERROR  
TRANSFER INHIBITED  
OUTPUT UV  
A, E  
A, E  
A, E  
A, E  
A, E  
Source 2 phase rotation error.  
A, E  
Transfer inhibited.  
A, E  
Output is under voltage.  
D, F, A, E  
Both History Logs have been written and no more history logs can be  
written without clearing one of the logs  
94  
HISTORY LOG FULL  
A, E  
96  
97  
INPUT 1 OV INPUT  
Source 1 over voltage  
Source 1 under voltage  
Source 2 over voltage  
Source 2 under voltage  
Output over current  
A, E  
A, E  
A, E  
A, E  
A, E  
A, E  
A, E  
A, E  
A, E  
A, E  
A, E  
A, E  
INPUT 1 UV INPUT  
98  
INPUT 2 OV INPUT  
99  
INPUT 2 UV INPUT  
100  
101  
102  
103  
104  
105  
106  
107  
LOAD OVERCURRENT  
GROUND OVERCURRENT  
Ground over current  
NEUTRAL OVERCURRENT Neutral over curremt  
LOAD VOLTAGE THD  
INPUT 1 CB6 OPEN  
INPUT 2 CB7 OPEN  
INPUT 1 OF/UF  
Voltage THD has exceeded the set limit  
Source 1 input Circuit Breaker 6 is open  
Source 2 Input Circuit Breaker 7 is open  
Source 1 over frequency/under frequency  
Source 2 over frequency/under frequency  
INPUT 2 OF/UF  
120  
121  
122  
123  
124  
125  
126  
127  
INPUT CONTACT #1  
INPUT CONTACT #2  
INPUT CONTACT #3  
INPUT CONTACT #4  
INPUT CONTACT #5  
INPUT CONTACT #6  
INPUT CONTACT #7  
INPUT CONTACT #8  
Input Contact # x is an optional alarm input. The alarm name can be  
programmed with an alarm name from the Input Contactor Isolator  
settings option under the Comm Options. See Configuring the Input  
Contact Isolator Settings on page 108. The alarm is sent to Monitor  
DSP. The LCD logs the alarm with the programmed name. Monitor  
DSP logs it with the generic name which is how it is reported to the  
SVT query.  
A, E  
128  
129  
130  
131  
132  
133  
134  
135  
CONFIG MODIFIED  
A setpoint configuration has changed.  
The password for touch screen access has been modified and saved.  
The system’s time has been reset and saved.  
The system’s date has been reset and saved.  
The event log has been erased.  
E
E
E
E
E
E
E
E
PASSWORD CHANGED  
TIME REPROGRAMMED  
DATE REPROGRAMMED  
EVENT LOG CLEARED  
HIST LOGS CLEARED  
XFER COUNT CLEARED  
KWH COUNT CLEARED  
Both History Logs have been erased.  
Transfer counter reset to 0  
KW-Hrs counter reset to 0  
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Communication Interfaces  
12.0 COMMUNICATION INTERFACES  
The STS2/PDU monitoring system offers several choices for communications.  
The RS-232 terminal port is standard on all units. The port is inside the front door, to the left of the  
touch screen front panel mounting as shown in Figure 55. This port is primarily used as an alternate  
user interface to configure, control and diagnose the system. Commands for the RS-232 port are  
shown in Table 13.  
Several other communications options are also available. Those options are located a Communica-  
tions compartment. See Figures 47 and 48 for the location of the communications options.  
Connections to the communication ports are made by wiring to terminal boards located in the Com-  
munications compartment. The communications options listed below reference the control wiring  
drawing for each option.  
• Internal modem (optional) — the connection to this modem is through a standard RJ-11 port. This  
port automatically dials the programmed telephone number when a designated alarm occurs.  
Automatic dial attempts are made to the first phone number at periodic intervals for 30 minutes.  
After that time, auto dial attempts are made to the second phone number at periodic intervals for  
the next 30 minutes. The process is repeated until a successful connection is made.  
Upon successful connection, the system transmits the status information and then hangs up. Sys-  
tem status and history information can be requested and date and time can be changed through  
the modem. The modem commands are shown in Table 13. See Figure 53 for more information  
on the internal modem.  
• Network Interface Card (NIC) (optional) — the NIC provides connectivity to any TCP/IP-based  
Ethernet network to allow the device to communicate with network management systems (NMS)  
via SNMP. Events can be transmitted to the NMS to provide remote status monitoring, plus fault  
and alarm detection. The NIC includes an RJ-45 port for an Ethernet connection, via Category 5  
cable.  
The NIC can also integrate the system with an existing Building Management System (BMS) or  
out-of-band monitoring, using Modbus, a standard multi-drop protocol. The NIC has redundant  
communication paths that make it possible to connect to a BMS using Modbus while simulta-  
neously communicate to a NMS through SNMP  
See Figure 54 for more information on the NIC. If you have questions about the NIC, refer to the  
OpenComms Network Interface Card installation and user guide.  
• Input Contact Isolator (ICI) Board (optional) — provides an interface for up to eight user inputs.  
External messages and alarms can be routed to the unit, via the ICI. See Configuring the Input  
Contact Isolator Settings on page 108 for instructions on configuring the connections. See  
Figure 51 for wiring details.  
• Programmable relay board (PRB) (optional) — up to two PRBs can be installed in the STS2/PDU  
to route STS2/PDU events to external devices. See Configuring the Programmable Relay  
Board Settings on page 109 for default settings and instructions for reconfiguring the relays.  
See Figure 50 for wiring details.  
• Comms Board (optional) — includes a terminal block to provide a DTE connection to an external  
modem. This board also provides a direct connection to a SiteScan terminal, via an RS-422.  
SiteLink-12 or SiteLink-4 is required for SiteScan to communicate with the STS2/PDU. See  
Figure 52 for wiring details.  
Data link requirements are Full Duplex Asynchronous RS-232 format.  
Communications options are also discussed in 6.0 - Options.  
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Communication Interfaces  
12.1 Using the RS-232 Port  
The RS-232 port is configured with a baud rate of 9600 with 8 Data Bits, 1 Stop Bit, No Parity and no  
hardware handshaking.  
12.1.1 Connecting and Using a Terminal  
An RS-232 connection can be used to connect the STS2/PDU to either a terminal or a PC running terminal  
emulation software. If you are unsure of the cable pin out, see 14.2.10 - Terminal Port Connections.  
1. Connect the terminal to the STS2/PDU by plugging the cable from the terminal into the RS-232  
port. This connection can be made at any time.  
2. After making the connection, verify the communications link by pressing <ENTER> on the  
terminal keyboard.  
The interface communications system responds as indicated below:  
Repeating command -->  
Illegal command!  
<?> or <HELP?> displays the RS-232 command set  
<?> <command> or <HELP?> <command> displays specific help for the command SVTP-Control>  
The SVTP-Control > prompt indicates that RS-232 communications are established.  
• If you receive no response or prompt, verify that the connector is properly plugged into the port  
and the PC or terminal serial interface is working properly.  
3. Enter the desired commands, as listed in Table 13.  
For additional help type <?> <command> or <HELP?> <command>  
Refer to the corresponding menu options in 13.0 - Touch Screen Display for more details about the  
commands.  
Some terminal commands require a password to function. Use the PWD command and a valid pass-  
word to gain access.  
Table 13 Terminal commands  
Keys  
Function  
Displays this help menu or specific help with a command  
Displays active alarms  
?
AA?  
AF?  
Displays active faults  
CEL  
Clears the event log  
CHL  
Clears the history logs  
DATE?  
DATE  
EL?  
Displays current system date  
Sets system date  
Displays the entire event log  
HELP?  
HLn?  
LOGOUT  
PS?  
Displays this help menu or specific help with a command  
Displays the history log #n, if frozen  
Logs user out of unprotected mode  
Displays the preferred source  
PS n  
PWD  
QUIT  
SH  
Sets the preferred source to #n  
Allows users to access protected commands  
Modem only. Ends the session and hangs up the modem.  
Silences the horn  
SPT?  
SPTx  
Displays all current setpoints  
Displays current setpoints for group x. See 12.1.2 - Configuring the STS2/PDU via the Terminal for  
a description of groups.  
SR?  
Displays status reports  
Displays current system time  
Sets system time  
TIME?  
TIME  
UPMDR?  
VER?  
Displays metering data  
Displays firmware versions  
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Communication Interfaces  
12.1.2 Configuring the STS2/PDU via the Terminal  
The SPT command is used to configure the systems setpoints. The SVT syntax for the setpoints con-  
sists for four parameters:  
SPT [group] [item] [value] where the parameters are:  
• SPT — is the terminal command that is used to configure setpoints.  
• group — the group under the setpoint command which contains the desired settings.  
• item — the item number within the selected group.  
• value — the desired value for this item.  
Only the specific options words listed in this section use a hexadecimal value. Other settings, depend-  
ing on what they are, use other input types. For example, System ID uses a text string; nominal volt-  
ages and currents use standard numeric integers; and modem baud rate uses an enumeration where  
0 = 2400, 1 = 9600, & 2 = 19200 bps.  
NOTE  
Spaces are placed between each parameter, but not between characters or numbers in a parameter.  
Using an underline here to represent a space, an example of a the syntax is: SPT_2_6_0081. The value  
parameter is 0081.  
This section provides instructions for setting these parameters, with an example of building an SPT  
command for System and User settings.  
Groups Parameter  
The setpoints are grouped for ease of configuration. For example, Event Masks are group 4 and Sys-  
tem Settings are group 2. The numbers shown below are entered for the group parameter. For exam-  
ple, start of a System Settings command is SPT 2.  
The group parameters are:  
1 = System Ratings  
2 = System Settings  
3 = User Settings  
4 = Event Mask Settings  
For example, the start of a System Settings command is SPT 2, where SPT is the system setpoints  
command and 2 is the group parameter for System Settings.  
See 12.1.4 - Setting Event Masks with the Terminal for instructions on configuring Event Mask  
parameters.  
Item Parameter  
Each setting within the group is indexed by an item number as shown below in Table 15. These item  
numbers are also displayed on the terminal when you list the configuration setting for a particular  
group.  
Continuing with the example, to configure an Options_1 setting under System Settings, the command  
would begin with SPT 2 6 where 6 is the value Options_1. Note the space between each parameter.  
89  
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Communication Interfaces  
Value Parameter  
Item settings, depending on what they are, use various value types.Table 14 provides a list of the  
possible value types and their description.  
Table 14 Value types  
Type  
Definition  
An integer numeric value in the units indicated by the item name. For example, a System Voltage  
Rating of 480 would indicate 480 volts.  
Numeric  
Similar to the Numeric, this value type is an integer that has been scaled, usually to remove decimal  
points that would normally appear within the value. In this case, a value of 2.5 may actually be input  
as simply 25. For all Scaled types, the scaling appears in Table 15.  
Scaled  
String  
Certain settings are represented by alphanumeric character strings, such as setting the System  
Model Number to ProductName.  
Enumeratio  
n
This type uses an indexed list to represent possible choices. One example is the Modem Baud Rate  
which uses a value of 0 to select 2400 bps, 1 for 9600 bps and 2 for 19200 bps.  
This type of value uses a hexadecimal binary word, where each of the sixteen bits in the word has  
the value of 1 (True) or 0 (False). Although somewhat difficult to use, it packs a large amount of data  
within a single entry. A detailed description of this type appears in section 12.1.3 - Setting  
Bit-packed  
This type is a specially formatted and is used to customize the behavior of each fault and alarm in  
the system. See 12.1.4 - Setting Event Masks with the Terminal for instructions on configuring  
Event Mask parameters.  
Event  
Masks  
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Communication Interfaces  
Table 15 shows the various groups, the settings contained within and the type of value it requires.  
Table 15 Group settings and values  
Group  
Item:  
1
Description  
Input Volts (PDU)  
Value Type  
Integer  
Value Notes  
Set per system spec.  
Group 1:  
System  
Ratings  
2
Volts  
Integer  
Set per system spec.  
3
Current  
Integer  
Set per system spec.  
4
Frequency  
Scaled  
Desired freq. x 10 (600 = 60 Hz)  
1
Language  
Enumeration [Not supported at this time]  
2
System Model Number  
System ID Number  
System Tag Number  
System Order Number  
Options_1  
String  
String  
String  
String  
Bitpacked  
String  
String  
String  
String  
String  
14 Character max.  
8 Character max.  
8 Character max.  
8 Character max.  
14 Character max.  
20 Character max.  
20 Character max.  
20 Character max.  
10 Character max.  
20 Character max.  
3
4
5
6
7
Autodial Primary Line  
Autodial Secondary Line  
Autodial Pager Number  
Autodial Pager PIN  
Modem Init String  
Group 2:  
System  
Settings  
8
9
10  
11  
12  
13  
14  
15  
16  
1
Modem Baud Rate  
Modem LGS Check - Day  
Modem LGS Check - Time  
Comms Options 1  
Comms Options 2  
SRC1 Fast Undervoltage Setpoint  
SRC1 Slow Undervoltage Setpoint  
Enumeration 0 = 2400, 1 = 9600, & 2 = 19200 bps  
Bitpacked  
Bitpacked  
Bitpacked  
Bitpacked  
Integer  
See section 12.1.3.  
See section 12.1.3.  
In % of nominal below nominal  
In % of nominal below nominal  
In number of lines cycles  
In % of nominal above nominal  
In 1/4 lines cycles  
2
Integer  
3
SRC1 Slow Undervoltage Detect Delay Integer  
4
SRC1 Overvoltage Setpoint  
Integer  
Integer  
Integer  
Integer  
Integer  
5
SRC1 Overvoltage Detect Delay  
SRC1 I peak Transfer Setpoint  
SRC2 Fast Undervoltage Setpoint  
SRC2 Slow Undervoltage Setpoint  
6
x 10  
7
In % of nominal below nominal  
In % of nominal below nominal  
In number of lines cycles  
In % of nominal above nominal  
In 1/4 lines cycles  
8
Group 3:  
User  
Settings  
9
SRC2 Slow Undervoltage Detect Delay Integer  
10  
11  
12  
13  
14  
15  
16  
17  
18  
1 to 63  
SRC2 Overvoltage Setpoint  
SRC2 Overvoltage Detect Delay  
SRC2 I peak Transfer Setpoint  
Max. Transfer Phase Angle  
Output Frequency Deviation  
ReTransfer Delay Time  
Integer  
Integer  
Integer  
Integer  
Integer  
Integer  
Integer  
Bitpacked  
Bitpacked  
x 10  
In degrees  
Freq. in Hz x 10  
In seconds  
Horn Volume  
Range: 1-10  
Critical Option Enabling  
See section 12.1.3.  
See section 12.1.3.  
Non-Critical Option Enabling  
Event Mask settings for faults  
Group 4:  
Event  
Event Mask See section 12.1.3.  
Mask  
Settings  
64 to 143 Event Mask settings for alarms  
Event Mask See section 12.1.3.  
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Communication Interfaces  
12.1.3 Setting Bitpacked Options With the Terminal  
Five sets of options and features settings are available through the terminal to control the system  
operation.  
Under System Settings for the SPT command, these items denote which options are INSTALLED:  
• 6 — Options_1  
• 14 — Comms Options 1  
• 15 — Comms Options 2  
Under User Settings, for the SPT command, these items denote which features are ENABLED:  
• 17 — Critical Option Enabling  
• 18 — Non-Critical Option Enabling  
The value parameter settings are in the form of a bit-packed word (in hexadecimal notation). In other  
words, each bit indicates a particular setting for the option or feature. The bit assignments for the  
options and features are as follows:  
Options_1  
bit0 —HasDualOutputBreaker  
bit1 — HasPDU  
bit2 — Has4PoleTransferSwitch  
bit3 — HasShuntTrip  
bit4 — HasWyeOutputXfmr  
bit5 — HasExternalPrecisionTimeSource  
bit6 — HasSFA  
bit7 — HasRemoteSourceSelect  
bit8 through bit15 — not used (set to 0)  
Comms Options 1  
bit0 — HasIntModem  
bit1 — HasExtModem  
bit2 — HasNIC  
bit3 — not used (set to 0)  
bit4 — HasSiteScan  
bit5 — not used (set to 0)  
bit6 — not used (set to 0)  
bit7 — HasOpenCommsDigitalInputBrd  
bit8 — HasOpenCommsDigitalOutputBrd_1  
bit9 — HasOpenCommsDigitalOutputBrd_2  
bit10 — HasRemoteStatusPanelBrd_1  
bit11 — not used (set to 0)  
bit12 — not used (set to 0)  
bit13 — not used (set to 0)  
bit14 — EnableDialIn  
bit15 — EnableDialOut  
Comms Options 2  
bit0 — EnablePager  
bit1 — EnableOCDINormallyClosed  
bit2-3 — OCDO1Assignment (0=User Defined, 1=Standard Set or 2=AS400)  
bit4-5 — OCDO2Assignment (0=User Defined, 1=Standard Set or 2=AS400)  
bit6 through bit15 — not used (set to 0)  
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Communication Interfaces  
Critical Option Enabling  
• bit0—EnableManual_IPeakReset  
• bit1—EnableAutoRestart  
• bit2 through bit15 - not used (set to 0)  
Non-Critical Option Enab  
bit0 — EnableAutoReXfer  
bit1 through bit15 — not used (set to 0)  
The bits are set in reverse order, from bit 15 on the left to bit 0 (zero) on the right. The bits are  
grouped in four sets of four bits each, as such:  
0000 0000 0000 0000  
|................................|  
bit 15.........................bit 0  
Since each bit represents a setting, a bit can be enabled or disabled:  
• 1 = installed option or enabled feature  
OR  
• 0 = option not installed or feature not enabled  
Enabling or disabling the bits in each group creates a binary value for that group. For example, if the  
fourth bit in a group is set to 1, the group’s binary value is 0001.  
Each group is translated into a hexadecimal equivalent. The group with the value of 0001 has a hex  
equivalent of 1.  
You can use Table 16 below to help with the conversion.  
Table 16 Binary-hexadecimal conversions  
Binary  
Value  
Hex  
Equivalent  
0000  
0001  
0010  
0011  
0100  
0101  
0110  
0111  
1000  
1001  
1010  
1011  
1100  
1101  
1110  
1111  
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
The hex value for each group is entered in the command as four digits.  
To summarize the procedure:  
1. Set each bit position.  
2. Convert the binary value each group into its hex equivalent.  
3. Enter the hex values for each group, in order, into the command for the value parameter.  
The following example explains how the conversion is completed.  
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Communication Interfaces  
Putting the Terminal Command Together  
For example, a unit only has the Remote Source Selection and Dual-Output Breaker options installed.  
Checking the bits list under Options_1 on page 92, bits 7 and 0 each must be set to 1 to indicate  
that these options are installed.  
The bit setting is as follows, starting with bit 15 on the left and going down to bit 0:  
0000 0000 1000 0001  
With the bits combined in groups of four, the binary settings can be translated into hexadecimal val-  
ues.  
The first two groups in the sample equal zero (0). In the third group, 1000 in binary translates to 8 in  
hex. In the fourth group, 0001 in binary translates to 1 in hex.  
In hex, this equates to (digits in the value parameter cannot have spaces between them):  
0081  
So your command to indicate that the Remote Source Selection and the Dual-Output Breaker are  
installed would be:  
SPT 2 6 0081  
12.1.4 Setting Event Masks with the Terminal  
The event masks can be customized via a terminal. The command SPT4?<ENTER> displays all faults  
and alarms, along with their associated event masks. A plus sign (+) means that particular event  
mask is enabled, while a minus sign (-) means that mask is disabled.  
Refer to 11.1 - Event Mask for more information on event masks and their associated flags.  
Unlike the System and User Settings, mask values are set by designated letters, not hex values.  
However, as with other RS-232 interface settings, four parameters are passed. See 12.1.2 - Configur-  
ing the STS2/PDU via the Terminal for more details about the parameters.  
The syntax for configuring event masks is:  
SPT 4 ID ±D±L±S±E±A  
• SPT — is the terminal command used to configure setpoints.  
• 4 — setting (group parameter) for event masks, under System Settings.  
• ID — event ID. The ID is the item parameter for this command. The ID numbers for each event  
are listed with the events in Table 12.  
• D,L,S,E,A — the event masks: Dial, Latch, Summary, Event log and Audible. The masks are the  
value parameter for the command.  
Each mask type must be preceded by a plus sign (+) to enable it or by a minus sign (-) to disable it.  
NOTE  
NO spaces are placed between each mask listed above.  
Only the mask that is passed (enabled) is applied when the event occurs.  
To set the event masks for a particular event:  
1. Enter the command. Examples and descriptions are provided below.  
2. Press ENTER.  
After the new settings are entered, the new results for that event ID are displayed.  
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Communication Interfaces  
Examples of Event Mask Settings  
• To latch event #001, S1 SCR SHORT, use SPT 4 1 +L.  
• To disable event #128, CONFIG MODIFIED, from sounding the horn, use SPT 4 100 -A.  
• To enable event #012, OUT VOLT SENSE FAIL, to Dial and go into the Event Log, use  
SPT 4 12 +D+E.  
• To disable all masks for event #120, INPUT CONTACT #1, use SPT 4 120 -D-L-S-E-A.  
• To breakdown this syntax for the last example:  
• SPT — SVT command  
• 4 — group parameter, identifying System Setting group under which the Event Mask settings  
reside.  
• 120 — item parameter. In this command, that is the event ID.  
• -D-L-S-E-A — value parameter. In this case, the minus sign (-)disables all masks for the INPUT  
CONTACT #1 event.  
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Touch Screen Display  
13.0 TOUCH SCREEN DISPLAY  
The STS2/PDU can be configured with a Color Graphical LCD touch screen display that allows you to  
quickly check the status of the unit and identify problems.  
A touch screen LCD is available through the front of the STS2/PDU. This screen provides a graphical  
(Mimic) display of the switch’s operation, plus system information including system parameters,  
alarms and faults.  
The LCD provides a color, back-lit touch screen as a user interface. In addition to the Mimic and the  
system parameters, the screen provides a series of menus to allow you to configure the STS2/PDU,  
including the control of the preferred source, auto/manual retransfer selection, alarm notification and  
other system setpoints. The touch screen also provides buttons to reset alarms and turn off audible  
alarms, such as a horn.  
13.1 Display Overview  
The STS2/PDU Color Graphical Display provides three areas of information, plus buttons and a series  
of menu choices.  
The Color Graphical Display contains the following features:  
Mimic — a graphical diagram of the status of the unit.  
Event controls — allow you to reset alarms and turn off audible alarms.  
Event display — displays any active alarm or fault condition, in real-time.  
Menus — provide choices and configuration settings in dialog boxes or information in the display  
panel.  
Display panel — provides additional information, depending on the menu choice that was last  
selected. This information includes event help text and startup and bypass procedures.  
Figure 62 STS2/PDU Touch Screen Display  
Mimic  
Event controls  
Display panel  
and  
help screen  
Event display  
Menu options  
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Touch Screen Display  
13.2 Menu Overview  
The touch screen menu provides access to configuration settings and more device information.  
The CONFIG (Configuration) and LOGS menus provide multiple choices through pop-up menus.  
The SOURCE XFER menu selection allows you to select the preferred source. The other menu choices  
provide information in the display panel. The menu choices are discussed later in this manual.  
All programmable functions are preset at the factory to default settings. These settings enable the  
unit to be brought up without the need to enter all selectable parameters. The menus allow the set-  
tings to be customized.  
Figure 63 Menus  
Logs  
Config menu  
Event Log  
System Rating  
History Log 1  
History Log 2  
Event Masks  
User Settings  
System Settings  
Comm Options  
System Options  
System ID  
NOTE  
Some menu choices display a keyboard or keypad on the touch screen. Enter data on the touch  
screen.  
Click OK to save the data that you have entered.  
Use the back arrow button (<-) to delete unwanted characters. This button functions like a  
backspace key on a keyboard.  
Figure 64 Keyboard and keypad displays  
Backspace  
Backspace  
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Touch Screen Display  
13.2.1 Security  
Because the STS2/PDU Color Graphical Display provides access to various configuration and moni-  
toring choices, a password or key lockout switch may be used to protect access to certain changes,  
including:  
• Change configuration settings  
• Clear logs  
• Make a source transfer  
• Reset an alarm  
Without entering the password or enabling changes with the key lockout switch, you still can:  
• View the display, including the mimic, status and event help  
• View logs  
• View the startup and bypass procedures  
• Use the SILENCE button to turn off the audible alarm  
Using the Optional Key Lockout Switch  
An optional key lockout switch for the STS2/PDU enables or disables the ability to make changes on  
the STS2/PDU. The key lockout switch is located on the front of the unit next to the display; it is  
behind the front door but can be operated without opening the front door. See Figures 20 through 22  
for location of the key lockout switch.  
• To disable the changes, turn the key to the top of the switch, toward the closed padlock.  
• To enable changes turn the key to the horizontal position, toward the open padlock.  
Figure 65 Key lockout switch  
Changes disabled  
Changes enabled  
Using the Password  
If the unit is not equipped with a keylock, a password is required when you attempt to:  
• Save changes in the CONFIG menu choices.  
• Transfer sources.  
• Reset active alarms.  
• Clear logs.  
When a password is requested, a keyboard is displayed on the touch screen. After you enter the pass-  
word, select OK.  
The password is case-sensitive. Password access times out after ten (10) minutes and must be  
re-entered to save changes. The time-out period cannot be changed.  
To set or reset the password:  
1. Select SYSTEM SETTINGS from the CONFIG menu.  
2. Select SYSTEM ID form the SYSTEM SETTINGS menu.  
3. Click PASSWORD. A keyboard is displayed.  
4. Enter a password. The password must be four (4) alpha-numeric characters and is case sensitive.  
5. Click OK.  
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Touch Screen Display  
13.3 Mimic Display  
The Mimic display provides a color diagram of the operation of the STS2/PDU. This display imitates  
the power flow through the Static Transfer Switch 2 Power Distribution Unit and indicates source  
status, breaker status, switch status, source voltage and current readings, output power measure-  
ments and active alarm messages. See Figure 62.  
13.4 Event Controls  
The STS 2 detects events when certain thresholds are passed or certain problems occur. The alarm  
controls allow you to acknowledge the existence of these events.  
• RESET — All latched events whose conditions have cleared are removed from the Event Display.  
Faults and alarms that remain active or are not recoverable are not affected when this button is  
selected. This button is also used to perform manual I-Peak resets and manual retransfers.  
• SILENCE — turns off the audible alarm (horn or beeper) without resetting the triggering event.  
This setting does not permanently turn off the horn. The alarm sounds again when the next event  
with an audible alarm setting is triggered.  
Active events are shown in the Event Display, whereas cleared events can be reviewed via the Event  
Log.  
13.5 Event Display  
The Event Display lists the condition of the STS2/PDU in real-time. Both nominal system parameters  
and alarm messages are displayed in the Event Display. You can touch any message in the Event Dis-  
play to display more information in the Display Panel to the left. The selected status is displayed in  
bold type.  
13.6 Menu Bar  
As previously mentioned, the menu bar provides both configuration choices and information. The  
choices under the Config and Log menus access additional dialog boxes, while the other menu choices  
only show information in the display panel.  
13.7 Configuration Menu  
When you select the CONFIG (Configuration) menu choice, a pop-up menu is dis-  
played with four choices.  
•SystemRatings— used to configure frequency, voltage and currents settings for  
the STS2/PDU.  
• Event Mask — allows you to configure system’s response for events.  
• User Settings — allows you to configure operations for the STS2/PDU.  
• System Settings — accesses another pop-up menu to configure communication  
and system choices and the system ID.  
Each of these choices accesses a separate dialog box.  
System Ratings  
The System Ratings menu is used to set the nominal line fre-  
quency, nominal voltage and nominal current at which the system  
operates when it is installed. These settings are configured when  
the system is initialized at the factory or under maintenance and  
should not be changed by the user.  
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Touch Screen Display  
Event Masks  
The STS2/PDU gathers, processes and reports faults and alarms, collectively referred to below as  
events. The Event Mask dialog box allows you to set the system’s response for specific alarms and  
faults that are generated. See 11.0 - Alarms and Faults for more information on events and 11.1 -  
Event Mask for the definitions of the Event Mask types.  
To set the event masks:  
1. Access the Event Mask dialog box:  
a. Select CONFIG.  
b. Select EVENT MASK from the pop-up menu.  
The Event Mask dialog box is displayed. See Figure 66.  
2. Select the mask settings for each fault and alarm.  
a. Select YES to enable the setting,  
OR  
b. Select NO to disable the setting.  
3. Select SAVE to keep the settings.  
Figure 66 Event Mask dialog box  
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Touch Screen Display  
User Settings  
The User Settings choice allows you to adjust the user-accessible switch settings. Access is limited to  
qualified personnel via system security.  
To access the User Settings dialog box:  
1. Select CONFIG.  
2. Select USER SETTINGS from the pop-up menu.  
The User Settings dialog box is displayed. See Figure 67. The top six buttons access a series of  
secondary dialog boxes to configure the various settings.  
Figure 67 User settings dialog box  
Source Setpoints  
The Source 1/2 Setpoints allows you to configure trigger points for each input source (1 or 2) for the  
STS2/PDU via a keypad dialog or HI/LO dialog box. The source numbers do not designate the source  
as the preferred or alternate source. The numbers simply identify the input source. See 10.2 - Man-  
ual Transfer / Preferred Source Selection to set the preferred source.  
The Setpoints are based on values in relation to the nominal voltage required for the STS2/PDU. UV  
refers to under voltage, meaning the amount of voltage below the nominal voltage. OV refers to over  
voltage or the amount of voltage over the nominal voltage.  
• Fast UV Setting (%) — if the voltage drops below this set percentage of the nominal voltage, the  
STS2/PDU transfers from the current source to the opposite source.  
• Slow UV Setting (%) — if the voltage remains this set percentage below the nominal voltage for  
the period of the slow detection delay, the STS2/PDU transfers from the current source to the  
opposite source.  
• Slow UV detection delay — the number of cycles that the source must remain below the Slow UV  
Setting before the STS2/PDU transfers.  
• OV Setting (%) — if the voltage exceeds this set percentage of the nominal voltage for the period  
of the OV detection delay, the STS2/PDU transfers from the current source to the opposite source.  
• OV Detection Delay — the number of cycles that the source must remain above the OV Setting  
before the STS2/PDU transfers sources.  
• I-PK Xfer Lockout — if current from the source exceeds this threshold, the STS2/PDU disables  
source transfers and has to be reset either manually or automatically. The type of reset is config-  
ured under the User Settings.  
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Touch Screen Display  
To configure the setpoints for each source:  
1. Select SOURCE 1/2 SETPOINTS from the User Settings dialog box. The Source 1/2 Setpoints  
dialog is displayed.  
Figure 68 Source setpoints  
2. Select 1 to configure the settings for Source 1.  
3. Configure the settings using the keypad or dialog box that is displayed when you touch a button.  
Table 17 Setpoint parameters  
Button  
Range  
Default  
Comments  
-10 to -30% of Nominal  
voltage rating  
Fast UV Setting (%)  
-20%  
Set in increments of 1%.  
Slow UV Setting (%)  
Slow UV detection delay  
OV Setting (%)  
-5 to -20%  
-10%  
Set in increments of 1%.  
Units: Line Cycle  
1-60 cycles  
+5% to +20%  
1-255 cycles  
5 cycles  
+10%  
Set in increments of 1%.  
Units: 1/4 Line Cycle  
OV Detection Delay  
3 cycles  
I-peak xfer lockout detection point.  
Units: Amps RMS. Select the HI or  
LO buttons to configure your setting.  
0 – 3.0 multiplied by  
the unit current rating.  
2.5 Times Unit  
Current Rating  
I-PK Xfer Lockout  
4. Select 2 for Source 2.  
5. Configure the settings, as described in step 3.  
6. Select SAVE to keep the settings for both sources. The Setpoints dialog is closed and the User  
Settings dialog is displayed.  
7. Select MANUAL MAX XFER PHASE ANGLE. A keypad is displayed.  
This setting configures the maximum allowed phase difference between the sources and applies to  
all manual transfers as well as any auto retransfer.  
a. Configure this setting with a range of +/- 1-30 degrees. The default setting is +/-15 degrees  
and the resolution is 1 deg.  
b. Select OK to save the setting. The setting is now displayed in the adjacent field in the User  
Settings dialog box.  
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Touch Screen Display  
8. Select FREQUENCY TRIP POINT. A keypad is displayed.  
This choice verifies that the source is running at the proper frequency. This choice sets the fre-  
quency deviation in the frequency that triggers the frequency trip point alarm. The frequency  
deviation setting is the allowable frequency variation from nominal (60 or 50 Hz) before activat-  
ing the frequency deviation alarm. The frequency setting applies to both input sources.  
a. Configure this setting with a range of 0.1 – 3.0 Hz. The default setting is 0.5 and the  
resolution is 0.1.  
b. Select OK to save the setting.  
9. Select RETRANSFER DELAY. A keypad is displayed.  
With the secondary source being used, this setting sets the length of time the switch waits until  
attempting to transfer back to the preferred source.  
a. Configure this setting with a range of 1 to 60 seconds. The default setting is three (3) seconds  
and the resolution is 1 second.  
b. Select OK to save the setting. The setting is now displayed in the adjacent field in the User  
Settings dialog box.  
10. Select AUDIO LEVEL. A dialog box is displayed with HI and LO settings.  
This choice sets the loudness of the horn or beeper that is sounded for audible alarms.  
a. Configure this setting with a range of 1–10 (ten). The default setting is 5. The settings have  
an increment of 1 (one).  
b. Select OK to save the setting. The setting is now displayed in the adjacent field in the User  
Settings dialog box.  
You can select TEST to briefly sound the alarm to judge its volume.  
11. Select DISPLAY BRIGHTNESS. A dialog box is displayed with HI and LO settings.  
This choice sets the brightness for the touch screen.  
a. Configure the Contrast and Brightness settings with a range of 1 – 10 (ten).  
b. Select OK to save the settings.  
12. Set the AUTO REXFER ENABLE choice. The auto retransfer enable setting determines whether  
the switch automatically returns the preferred source after that source is restored.  
• Select YES to enable the automatic transfer.  
• Select NO to disable the automatic transfer. The setting requires transfers be done manually.  
13. Set the AUTO RESTART ENABLE choice. This setting determines whether the STS2/PDU can  
be started automatically when power is restored after it has been lost.  
Select YES to enable the automatic restart.  
Select NO to disable the automatic restart. This settings requires a manual restart of the  
STS2/PDU.  
To manually restart theSTS2/PDU:  
a. Select SOURCE TRANSFER from the MENU bar. The SELECT PREFERRED SOURCE  
window is displayed.  
b. Select Source 1 or Source 2 as your preferred source. The unit will restart.  
14. Select a setting for the I-PEAK RESET.  
Select AUTO to configure the Static Transfer Switch 2 Power Distribution Unit to automati-  
cally reset when a fault clears and the voltage and current are normal.  
Select MAN to require a manual reset of the Static Transfer Switch 2 Power Distribution Unit  
when fault clears and the voltage and current are normal.  
CAUTION  
!
Risk of equipment damage and personnel injury.  
Use of Auto Restart is site specific. Do not enable auto restart unless the infrastructure is  
designed for unattended operation and there is no chance of equipment or personnel harm by  
automatic re-energizing of the system.  
Consult with your Liebert site Engineer as to whether Auto restart should be enabled.  
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Touch Screen Display  
PDU Setpoints  
The PDU Setpoints option allows you to configure the following parameters for the PDU, shown in  
• Load Voltage THD (%)  
• Neutral Current (% of nom)  
• Ground Current (A)  
• Load Bus Overcurrent (% of nom)  
Figure 69 PDU setpoints  
Table 18 shows the range of valid values, default values and resolution for each parameter.  
Table 18 PDU setpoints  
Button  
Range  
Default  
15.0%  
95%  
Resolution  
Load Voltage THD (%)  
Neutral Current (% of nom)  
Ground Current (A)  
3.0% to 99.9%  
10% to 200%  
1.0A to 50.0A  
50% to 100%  
0.1  
1
5.0A  
0.1  
Load Bus Overcurrent (% of nom)  
100%  
System Settings  
The System Settings choice under the Config menu displays another pop-up menu with three choices:  
• Comm Options  
• System Options  
• System ID  
To access the System Settings menu:  
1. Select CONFIG from the menu bar.  
2. Select SYSTEM SETTINGS from the Config menu.  
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Touch Screen Display  
Comm Options  
The Comm Options dialog box allows you to configure the communications settings for the STS2/  
PDU.  
• Select COMM OPTIONS from the System Settings Menu.  
• The Comm Options dialog box is displayed. See Figure 70.  
• An option can be enabled by selecting YES.  
• An option can be disabled by selecting NO.  
• An option can be configured by selecting the adjacent option button to display a separate configu-  
ration dialog box.  
The instructions for configuring the communications options are provided in this section.  
Figure 70 Comm options dialog box  
Option  
buttons  
Configuring the Modem  
The Modem dialog box allows you to configure the optional, internal modem or an external modem  
that is connected to the Static Transfer Switch 2 Power Distribution Unit. Only one modem can be  
utilized by the STS2/PDU.  
The dialog box contains a series of choices that access either a keypad or a secondary dialog to config-  
ure settings. Auto dial can also be configured for the modem to be triggered by events, as set up in the  
Event Mask choices.  
Designated major alarms activate the auto dial modem sequence. Automatic dial attempts are made  
to the first number three times, at 30 seconds between attempts. If connection is not established in  
that time period, the system automatically rolls over to the second number. Auto dial attempts are  
made again three more times at 30 seconds between attempts. The process is repeated until a success-  
ful connection is made. Upon successful connection, the system transmits a present status data,  
including all active alarms messages. After transmission, the modem automatically hangs up and  
returns to the auto-answer mode.  
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Touch Screen Display  
To configure the modem:  
1. Select MODEM from the Comm Options menu. The Modem dialog box is displayed.  
Figure 71 Modem dialog box  
2. Select the type of modem that the STS2/PDU will be using:  
• Select INT if the STS2/PDU will be communicating via an internal modem.  
• Select EXT if the STS2/PDU will be communicating via an external modem.  
3. Select the PRIMARY LINE choice to enter the primary telephone number for the modem to dial  
when an alarm is triggered.  
4. Enter the number in the keypad dialog box.  
5. Select OK to save the telephone number. The number is displayed in the field adjacent to the  
Primary Line choice.  
6. Select the SECONDARY LINE choice to enter the secondary telephone number for the modem to  
dial when an alarm is triggered.  
7. Enter the number in the keypad dialog box.  
8. Select OK to save the telephone number. The number is displayed in the field adjacent to the  
Secondary Line choice.  
9. Select INIT. STRING to configure the initialization string. This string configures the parameters  
of the modem.  
• This setting only needs to be configured if an external modem is used. Check your modem’s  
documentation for this setting.  
• The string for the internal modem set by the manufacturer and does not need to be changed.  
10. Select BAUD RATE to display a dialog with the baud rate choices:  
• For an external modem, select from 2400 bps, 9600 bps or 19200 bps.  
• An internal modem only supports 2400 bps.  
11. Configure the MODEM HEALTH CHECK. The Health Check verifies that the modem is working  
properly. This setting allows you to enable the check and set when it is run.  
a. Select the button to display the Modem Health Check dialog box, from which you can access  
further dialogs to set the time and days that the check is run.  
b. Select SAVE to keep the settings.  
The Health Check dialog box is closed and the Modem dialog box is again active.  
c. Select YES in the Modem dialog box to activate the Modem Health Check. If you select NO,  
the Modem Health Check is not run.  
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Touch Screen Display  
12. Configure AUTO DIAL IN. Auto Dial In allows a user to dial into the STS2/PDU through the  
modem to check status and access the system via a hyperterminal connection.  
a. Select YES to activate the dial in feature.  
b. Select NO to deactivate the dial in feature.  
13. Configure AUTO DIAL OUT. Auto Dial Out allows the STS2/PDU to automatically dial out to a  
system to notify a user of an event or status.  
a. Select YES to activate the dial out feature.  
b. Select NO to deactivate the dial out feature.  
14. Select SAVE to keep the modem configuration settings.  
15. Select YES in the Comm Options dialog box to activate the settings. You are returned to the  
Comm Options dialog box.  
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Touch Screen Display  
Configuring the Input Contact Isolator Settings  
The Input Contact Isolator (ICI) is an optional, eight-channel input board for up to eight external user  
alarm or message inputs to be routed to the Static Transfer Switch 2 Power Distribution Unit’s alarm  
network.  
The contact is set to either be normally open or normally closed. When a contact closes or opens, an  
event is triggered. See 6.2 - Input Contact Isolator Board for more information on the ICI.  
The Input Contact Isolator options are configured through the Input Contact Isolator dialog box,  
which is accessed from the Comm Options dialog box. The Input Contact Isolator dialog box contains  
eight choices to match the eight channel input board. You can label each button to identify the event  
associated with the contact. When the dialog box is accessed, each button flashes to display the Input  
Contact Isolator number and the user entered label. This label also appears in the Display Panel  
when an event related to an Input Isolator Connector is triggered.  
The Input Contact Isolator dialog box allows you to:  
• Label the input contact assignments for your setup.  
• Set the delay for an external event triggering an alarm.  
• Review the isolator contact assignments, once the labels are entered.  
The delay allows you to set the number of seconds which a condition needs to persist to trigger an  
alarm.  
These input alarms can also be configured to activate a programmable relay output, which is dis-  
To configure the Input Contact Isolator relays:  
1. Select INPUT CONTACT ISOLATOR from the Comm Options menu.  
The Input Contact Isolator dialog box is displayed.  
Figure 72 Input Contact Isolator dialog box  
2. Select INPUT CONTACT 1.  
A keyboard is displayed to allow you to enter the name of the alarm.  
3. Enter the name of the alarm set for that input. For example, a fan problem could be indicated by  
naming the button FAN.  
4. Select OK on the keyboard to keep your label.  
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Touch Screen Display  
5. Select DELAY.  
A keypad is displayed prompting you for a delay time, in seconds, for a condition to exist before  
the alarm is triggered.  
6. Enter the delay value. The range for the values are from 0 (zero) to 99.9 seconds.  
7. Select OK on the keypad to keep your setting.  
The value you entered is displayed in the field adjacent to the corresponding input contact.  
8. Repeat Steps 2 to 7 for each input contact.  
9. Select SAVE after you have configured all input contacts.  
Be sure to select Save even if you have accessed this dialog only to change a setting.  
This information is not saved if control power is removed.  
11. Select OK in the Comm Options dialog box to activate the settings.  
Configuring the Programmable Relay Board Settings  
The STS2/PDU can contain up to two programmable relay boards (PRB) that can trigger an external  
device when an event occurs in the Static Transfer Switch 2 Power Distribution Unit. For example, if  
Source 1 fails, an external light flashes.  
See 6.1 - Programmable Relay Board for more information on the PRBs.  
The programmable relay board dialog box with two options: STANDARD SET and USER DEFINED  
SET. The STANDARD SET are the factory-configured settings.  
The STANDARD SET for the programmable relay board settings are:  
Table 19 Standard settings for programmable relays  
Relay  
Setting  
Definition  
1
2
3
4
5
SOURCE 1 FAIL  
Source 1 failure  
Source 2 failure  
SOURCE 2 FAIL  
BYPASS CB4 CLOSED  
BYPASS CB5 CLOSED  
TRANSFER INHIBIT  
Switch (CB4) is closed; Source 1 is bypassed.  
Switch (CB5) is closed; Source 2 is bypassed.  
A transfer between Source 1 and Source 2 is being restrained.  
The phase difference between sources 1 and 2 exceeds the  
allowable threshold for transfer.  
6
OUT OF SYNC  
The ambient temperature of the ProductName exceeds the  
recommended threshold for operation.  
7
8
EQUIP OVER TEMP  
Blank  
No setting  
The USER DEFINED SET allows you to assign faults and alarms to each contact on the relay boards.  
Utilizing the USER DEFINED SET, you can also select Input Contact Isolators to associate with a  
programmable relay.  
In addition individual events, three other assignment choices are available:  
• SELECT ALL sends a summary event to the selected relay whenever any event occurs. If this set-  
ting is selected for a relay, no other event needs to be assigned for that relay.  
• ON SOURCE 1 or ON SOURCE 2 can be assigned to a relay to send a notification when that  
source is being used by the load.  
Once configured, the Static Transfer Switch 2 Power Distribution Unit continuously checks the status  
of the items defined for each contact and updates the state of the relay.  
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Touch Screen Display  
To configure your programmable relay boards for user defined settings:  
1. Select PROG. RELAY BOARD # x from the Comm Options dialog box, where x is the  
corresponding board number.  
The Prog. Relay Board dialog box is displayed.  
Figure 73 Programmable relay board dialog box  
2. Select your configuration settings.  
• Select STANDARD SET to use the settings configured at the factory. See Go to step 4.  
• Select USER DEFINED SET to configure your own settings. Go to step 3.  
If you enter a user defined settings, this information is not saved if control power is removed.  
Record the settings in Table 31.  
3. To define your relay board settings:  
a. Select a Programming Relay.  
b. Select an event you want associated with the relay. That fault is placed in the Relay column.  
You can associate up to ten (10) events with one relay. If you do so, you should group the events  
logically to simplify troubleshooting when an event is triggered.  
4. Select SAVE to keep the settings.  
5. Select OK for the applicable Programmable Options Board option in the Comm Options dialog box  
to activate the settings.  
Configuring the Network Interface Card  
An optional Liebert OpenComms Network Interface Card (NIC) can be installed in the STS2/PDU to  
provide Ethernet connectivity via an RJ-45 port.  
Ethernet cabling is the responsibility of the customer. Category 5 cabling is required.  
See 6.5 - Network Interface Card (NIC) for more information on the NIC.  
See the OpenComms Network Interface Card Installation and Users Guide for configuration instruc-  
tions for the card.  
If the optional OpenComms NIC is installed in the STS2/PDU:  
• Select YES for the Network Interface Card option in the Comm Options dialog box to activate the  
card.  
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Touch Screen Display  
SiteScan Configuration  
An RS-422 port on the optional Comms Board provides communications with Liebert’s SiteScan.  
SiteScan is Liebert’s system monitoring software that allows you to utilize a PC to monitor the Static  
Transfer Switch 2 Power Distribution Unit’s status and check alarms. See 6.3 - Comms Board for  
more information on this board.  
If the STS2/PDU will be connected to SiteScan:  
• Select YES for the SiteScan choice in the Comm Options dialog box to activate the card.  
Saving Your Communications Configurations  
To save you communications configuration settings:  
1. When you have completed the Comm Options configurations, ensure you have selected YES for all  
the settings that you want activated.  
2. Select SAVE to keep the settings.  
Whenever you make modifications to the any of the Comm Options, select SAVE to keep the  
changes.  
System Options  
Most System Options are configured at the factory. However, you may need to set two of the choices  
after the unit is installed: Wye Output Transformer and Remote Source Selection.  
• Select SYSTEM OPTIONS from the System Settings Menu.  
The System Options dialog box is displayed.  
• An option is enabled by selecting YES.  
• An option is disabled by selecting NO.  
Figure 74 System options  
Dual Output Breaker  
This selection is set at the factory. The choice is set to YES to enable both output breakers (CB3 and  
CB3A) when two are installed in the unit. If only one output breaker (CB3) is installed, the setting is  
set to NO.  
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Touch Screen Display  
PDU  
This selection is set at the factory to YES, which allows the LCD to draw the Mimic accordingly and  
display PDU metering and alarm information.  
Select the PDU button in the System Options window (see Figure 74). This opens the PDU Options  
window, shown below in Figure 75.  
Figure 75 PDU options button  
The PDU Options window allows you to specify whether you have the surge suppression option.  
• If the TVSS option is installed, this selection is set at the factory to YES. To disable surge sup-  
pression, click NO.  
• Click SAVE.  
4 Pole Transfer Switch  
This selection is set at the factory to indicate whether the system is a 3 pole or 4 pole unit. The 4 pole  
design is not available at this time.  
Shunt Trip  
This selection is set at the factory.  
Wye Output Transformer  
The Wye Output Transformer controls the firing of the SCRs on startup, which minimizes the inrush  
into PDU transformers. Output breakers and PDU input breakers have to be closed when you start  
up the system. Based on whether the input side of the PDU transformer is configured as a Wye or  
Delta changes the firing sequence of the SCRs.  
If the STS2/PDU is connected to a PDU configured as a Wye:  
• Select YES for the Wye Output Transformer choice in the System Options dialog box.  
Remote Source Select  
If your system is configured with the optional Remote Source Selection, it must be enabled from the  
System Options menu. See 4.4 - Remote Source Selection Wiring for more information.  
If the system is utilizing Remote Source Selection:  
• Select YES for the Remote Source Select choice in the System Options dialog box to activate the  
option.  
System ID  
Most of the settings for System ID are set by Liebert either at the factory or when the unit is  
installed.  
The system is identified and tracked with these numbers: Order No., System Tag No., System ID No.  
and Model No.  
Language, Time and Date are synchronized with the location of the unit.  
The only configurable field is the Password. See Using the Password on page 98 for more informa-  
tion on configuring and using the password.  
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Touch Screen Display  
13.7.1 Logs  
Two types of logs are kept by the STS2/PDU: Event Log and History Log.  
Event Log  
The Event Log tracks the alarms and faults of the STS2/PDU.  
See 11.0 - Alarms and Faults for more information on these events and see 11.2.1 - Event Log for  
more information on the Event Log and definitions of the fields displayed in the Event Log screen.  
Figure 76 Event log  
To use the Event Log:  
1. Select LOGS from the menu bar to open the Logs menu.  
2. Select EVENT LOG from the menu.  
3. Use the UP and DOWN buttons to scroll through the event list.  
4. Select OK to close the Event Log. The data remains in the log.  
History Log  
Two History Logs are available to track major alarms. If so configured, an alarm freezes the history  
buffer. When the History Status buffer is frozen, a History Log is created that can be accessed from  
the HISTORY LOG x choices in the LOGS menu.  
See 11.2.2 - History Log for more information on the History Logs and definitions of the fields dis-  
played in the History Log screen.  
Figure 77 History log  
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Touch Screen Display  
To use the History Log:  
1. Select LOGS from the menu bar to open the Logs menu.  
2. Select either HISTORY LOG 1 or HISTORY LOG 2 from the menu.  
3. Select the appropriate buttons to replay the log:  
• Select PREV to go to the previous frame in the sequence.  
• Select NEXT to go to the next frame in the sequence.  
• Move the green cursor to the location from which you would like to play the sequence of events.  
• Select REPLAY to play the frames automatically from the point of the cursor.  
• Select STOP to halt the replay.  
• Select RESET to return to the first frame in the log.  
4. Select EXIT to close the History Log. The data remains in the log.  
• Use CLEAR HLOGS to remove the data from both history logs.  
NOTE  
Event and History Logs are protected by security. The password or a disabled key lockout is required on  
such equipped units to clear these logs.  
13.7.2 Source Transfers  
The Source Transfer choice (SOURCE XFERS) allows you to manually select a preferred source.  
To switch the primary source, refer to 10.2 - Manual Transfer / Preferred Source Selection.  
13.7.3 Startup Procedure  
You can access instructions for starting the STS2/PDU from the menu bar.  
• From the menu bar, select STARTUP PROC.  
These instructions are also provided on 10.1 - Normal System Turn-On.  
13.7.4 Bypass Procedure  
You can access instructions for bypassing the Static Transfer Switch 2 Power Distribution Unit from  
the menu bar.  
• From the menu bar, select BYP. PROC.  
The instructions are provided in the display panel.  
Bypass procedures are also discussed in 10.4 - Maintenance Bypass.  
13.7.5 Help  
You can select an event in the Event Display to display more information about that event in the Dis-  
play Panel. This same help is also available in 15.0 - Event Message Help Text.  
13.7.6 Logo  
The Logo menu choice shows the Liebert and Emerson logo in the Display panel.  
13.8 Cleaning the LCD Touch Screen  
If the touch screen requires cleaning, use a pre-moistened towelette designed for cleaning CRTs or  
dampen a soft, non-abrasive cloth with a very mild cleaning solution.  
Do not spray the cleaner directly onto the touch screen, as drips may run down into the screen and  
damage the equipment.  
Close all menus and dialog boxes before cleaning the touch screen.  
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Specifications  
14.0 SPECIFICATIONS  
14.1 System Configuration  
The STS2/PDU can be set in several different configurations, according to the model and location. The  
configuration is set at the factory and does not need to be changed by the customer.  
14.1.1 Frequency  
The STS2/PDU accepts input frequencies of 50 Hz or 60 Hz, depending on the model ordered. The fre-  
quency shall be within +/- 0.5 Hz of the nominal frequency.  
14.1.2 Input Voltage  
The STS2/PDU models are available to handle various voltages.  
The input voltage must be three phase AC (3 wire-plus-ground).  
The voltage shall be within +/- 10% of the nominal voltage.  
The following table provides nominal voltages, listed according to frequency.  
Table 20 Input voltage  
60 Hz  
(L-L)  
50 Hz  
(L-L)  
208V  
380V  
400V  
415V  
480V  
600V  
208V  
380V  
400V  
415V  
-
-
14.1.3 Output Voltage  
The output voltage shall be three phase AC (4 wire-plus-ground).  
Table 21 Output voltage  
60 Hz  
(L-L/L-N)  
50 Hz  
(L-L/L-N)  
208/120V  
380/220V  
400/230V  
415/240V  
208/120V  
380/220V  
400/230V  
415/240V  
14.1.4 System Current Ratings  
These ratings are based upon continuous switch current rating. All units are 100% continuous cur-  
rent rated. Some ratings are not available in certain voltages.  
Table 22 System current ratings  
Current  
250A  
400A  
600A  
800A  
14.1.5 Grounding  
Refer to 4.2 - System Grounding for specifications and instructions regarding grounding.  
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Specifications  
14.1.6 Electrical Requirements  
Table 23 Electrical requirements  
Item  
Requirement  
Maximum Continuous Current  
Load Power Factor Range  
Load Crest Factor  
250, 400, 600, 800 amps  
0.75 to 1.0, leading or lagging  
Up to 3.5  
Source Voltage Distortion  
Up to 10% THD with notches and ringing transients  
125% for 30 minutes 250A-400A  
125% for 10 minutes 600A-800A  
150% for 2 minutes  
Overload Capability  
500% for 0.25 sec  
Table 24 Unit short circuit withstand capability  
Unit Voltage  
Unit Amps  
250A  
Withstand Capability  
100kA  
100kA  
100kA  
65kA  
208-240V  
400-600A  
800A  
250A  
380-480V  
400-600A  
800A  
100kA  
65kA  
250A  
25kA  
600V  
400-600A  
800A  
25kA  
42kA  
14.1.7 Surge Suppression  
The static transfer switch is equipped with transient voltage surge suppression on each input for  
surge suppression. The surge suppression is capable of protecting the static transfer switch from  
operating outside of tolerances due to surges as defined by IEC 1000-4-5 (1.2/50uS surge, 2kV CM and  
1kV DM) as required under EN 50091-2. Optional surge suppression modules (TVSS) are available  
for each input of the STS2/PDU for surge protection of the transformers.  
14.1.8 Response Time  
A dual level fast/slow transfer threshold is used for under voltage detection to allow the STS2/PDU to  
be compatible with UPSs and generators. The voltage thresholds and the slow transfer delay time is  
user-adjustable. The fast transfer delay time is less than 4 ms.  
The over voltage detection uses a single threshold, with programmable level and delay time. See User  
Settings on page 101 for instructions on configuring these settings.  
14.1.9 Environmental Requirements  
See 3.0 - Locating The STS2/PDU for details concerning environmental requirements for the STS2/  
PDU.  
14.2 System Components  
All STS2/PDU models provide two isolation transformers connected to a solid-state, three-pole dual-  
position static transfer switch within one enclosure, with the ability to transfer between two input  
sources to a single output.  
All STS2/PDUs are configured with an LCD Color Graphical Interface touch screen display for moni-  
toring and configuring the unit.  
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Specifications  
14.2.1 Frame and Enclosure  
The complete STS2/PDU is housed in a freestanding enclosure. The cabinet is a NEMA type 1 enclo-  
sure. The cabinet is structurally designed to handle lifting from the base. The frame is designed to  
accommodate floor stands.  
Table 25 Frame sizes  
Width x Depth x Height  
Rating  
in. (mm)  
250A  
60 x 32 x 77 (152 x 81 x 196)*  
73 x 49 x 77 (186 x 125 x 196)  
96 x 49 x 77 (244 x 125 x 196)  
400 – 600A  
800A  
* Width is 76.8 in (195 cm) with output distribution cabinet  
The distributed floor weight for STS2/PDU is less than 260 lbs./sq. ft. (118 kg/m²).  
The required service access is front and one side of the unit, 250A without output cabinet is front  
access only. Side access depends on which side the output cabinet is mounted, can be left or right.  
The STS2/PDU can be tipped 15° in any direction without falling over.  
14.2.2 Caster and Leveling - 250A only  
The 250A unit frame includes heavy-duty swivel casters for ease of installation, plus permanent level-  
ing feet for final installation.  
14.2.3 Cooling  
The STS2/PDU 250A units utilize convection air cooling for the enclosure with forced air cooling of the  
heat sinks.  
The 400-800A units are fan cooled using low-velocity fans to minimize audible noise. All fans are  
redundant so that a single fan failure cannot cause temperatures to increase beyond acceptable lim-  
its.  
Air intake is through screened protective openings in the front of the unit. A standard furnace filter  
is installed behind the openings.  
By opening the front door, the filter can be changed easily without exposing personnel to high voltage.  
The size of the filter is 1 in. x 25 in. x 25 in. (2.54 cm x 63.5 cm x 63.5 cm).  
The air exhaust is through the top of the unit.  
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Specifications  
14.2.4 Access  
The STS2/PDU is designed so repairs and maintenance can be done from the front, side or top of the  
unit. All components that may need repair or replacement during routine field maintenance are  
safely accessed with the units in bypass without removing power from the unit. These components  
include:  
• All electronic PCB assemblies  
• Power supply assemblies  
• All control fuses  
• All circuit breaker plug-in modules  
• Fans  
• SCRs  
All power connections are designed to maintain proper connection torque over the lifetime of the unit  
without any maintenance. The integrity of the connections can be checked via infrared scanning  
safely from the front or top of the unit.  
All other components including transformers, power cables and connections, circuit breaker bases,  
etc., are replaceable from the front, rear or top of the unit, but this requires all power to be removed  
from the unit for safety. Although routine re-torquing of the power connections is not required, if  
maintenance of these connections is needed, complete removal of power is required from the unit for  
safety reasons.  
WARNING  
!
Lethal voltages exist inside the unit during normal operation. Only qualified service  
personnel should perform maintenance on the Static Transfer Switch 2 Power Distribution  
Unit.  
The unit is supplied by more than one power source. The unit contains hazardous voltages if  
any of the input sources is on, even when the unit is in bypass. To isolate the unit, turn off and  
lock out all input power sources.  
Verify that all input power sources are de-energized and locked out before making connections  
inside unit.  
14.2.5 Circuit Breakers  
The STS2/PDU is equipped with two input plug-in circuit breakers and five or six (if CB3A is used)  
molded-case, plug-in, non-automatic circuit breakers. The breakers are UL listed for use up to  
600VAC and CE marked. The plug-in feature of the breaker includes an interlock, which prevents the  
breaker from being unplugged without being in the OFF (open) position.  
Mechanical interlocks are provided on the breakers to prevent improper maintenance bypassing of  
the solid-state switch. A bypass breaker cannot be closed unless the solid-state switch is connected to  
the same input source and only one bypass breaker can be closed at a time. All breakers are equipped  
with N.O. and N.C. auxiliary switches for monitoring of the breaker positions. The two solid-state  
static switch input breakers are equipped with 48 VDC shunt trips to allow for control by the STS2/  
PDU logic. See Tables 9 through 11.  
14.2.6 Cable Entrance  
Removable conduit termination plates are provided in the top and bottom of the STS2/PDU for termi-  
nation of the two source input conduits or raceways and/or the output conduits or raceways. On units  
with inline panelboards, output conduit or raceways are bottom exit only.  
14.2.7 Doors  
A removable key lock hinged front door provides access to the circuit breakers.  
14.2.8 Color Graphical Display  
The display is located in the front of the unit. Front panel display is an LCD touch screen display for  
monitoring and configuring the unit. See Figure 57 for a drawing of the touch screen display.  
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Specifications  
14.2.9 RS-232 Port  
The unit is equipped with an RS-232 port for connecting a terminal or PC. See Figure 55 for the  
port’s location. See 12.1 - Using the RS-232 Port for instructions on using a PC terminal with the  
unit.  
14.2.10 Terminal Port Connections  
The system has an asynchronous serial port configured as Data Terminal Equipment for terminal  
access only (half duplex). The CPU services the terminal port with no handshaking. The serial port  
conforms to RS-232 levels with a data format of 9600 Baud, 1 start bit, 8 data bits and no parity bits.  
The serial port is 1000VDC isolated (non-SELV) and ESD protected to 15kV air discharge.  
The connector is a 6 Pin MTA plug with connections shown below.  
Table 26 MTA plug pinout  
Pin Signal Name  
Function / Comments  
Isolated service terminal ground  
Isolated service terminal transmit output  
Isolated service terminal receive input  
No Connection  
1
2
3
4
5
6
ISO_GND  
ISO_TXD  
ISO_RXD  
NC  
NC  
No Connection  
NC  
No Connection  
A DB9 male connector is added and connected parallel to the 6 position header. It is configured as  
DTE.  
Table 27 DB9 pinout  
Pin Signal Name  
Function / Comments  
No Connection  
1
2
3
4
5
6
7
8
9
NC  
ISO_RXD  
ISO_TXD  
NC  
Isolated service terminal transmit output  
Isolated service terminal receive input  
No Connection  
ISO_GND  
NC  
Isolated service terminal ground  
No Connection  
NC  
No Connection  
NC  
No Connection  
NC  
No Connection  
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Specifications  
14.2.11 RS-232 Interface Parameters  
The service terminal interface parameters are the following settings and cannot be changed.  
Table 28 RS-232 settings  
Parameter  
Setting  
Interface  
RS-232 Using EIA Voltage Levels  
Baud Rate  
9600  
Parity  
None  
Number of Data Bits  
Number of Stop Bits  
Hardware Flow Control  
Terminator  
8
1
Off  
<CR> <LF>  
Not supported  
Full duplex  
Off  
Handshaking  
Structure  
Local Echo  
14.2.12 Maintenance Bypass  
The STS2/PDU is configured to allow the unit’s electronics to be bypassed to either input source for  
maintenance without interruption of power to the load.  
The STS2/PDU is furnished with key-interlocked maintenance bypass breakers to configure the  
bypass.  
STS2/PDU units have all electronics isolated from the input, output and bypass connections to allow  
safe servicing of any components without access to hazardous voltages when the unit is in mainte-  
nance bypass.  
See 10.4 - Maintenance Bypass for instructions.  
14.2.13 Fuseless Design  
All STS2/PDU units are fuseless.  
14.2.14 Options  
The following options are available for the STS2/PDU:  
• Panelboards  
• Subfeed Breakers  
• K-Factor Transformers  
• Surge Suppression System (TVSS)  
• Redundant Static Switch Output Breaker  
• Programmable Relay Board  
• Comms Board w/SiteScan and Modem Interface  
• Internal Modem  
• Input Contact Isolator Board  
• Network Interface Card (NIC)  
• Remote Source Selection  
• Key Lockout Switch  
• Export Crating  
See 6.0 - Options for more information.  
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Event Message Help Text  
15.0 EVENT MESSAGE HELP TEXT  
Key  
ALL CAPS = Event message displayed in the Event Display panel in the lower left corner of the LCD.  
Indented text = Help text shown in the Display Panel in the lower right corner of LCD.  
BOLD = Commands that are sent through the RS-232 port.  
S1 SCR SHORT  
Source 1 SCR Short  
One or more of the SCRs for Source 1 has shorted. Transferring between sources has been inhibited.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
S2 SCR SHORT  
Source 2 SCR Short.  
One or more of the SCRs for Source 2 has shorted. Transferring between sources has been inhibited.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
S1 SCR OPEN  
Source 1 SCR Open.  
One or more SCRs on Source 1 is open. Transferring between sources has been inhibited.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
STS2/PDU output has been transferred to Source 2.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
121  
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Event Message Help Text  
S2 SCR OPEN  
Source 2 SCR Open.  
One or more SCRs on Source 2 is open. Transferring between sources has been inhibited.  
STS2/PDU output has been transferred to Source 1.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
PRIMARY FAN FAIL  
Primary Fan Failure  
One of the primary cooling fans for the STS2/PDU has failed. The alternate fans are now running. The alter-  
nate fans are not monitored.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
CONTROL MODULE FAIL  
Control logic module has failed.  
One of the control modules on the control board has failed.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
PWR SPLY DC A FAIL  
Power Supply DC Bus A Failed  
The primary power supply is no longer providing DC power to the control board and the touch screen.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
PWR SPLY DC B FAIL  
Power Supply DC Bus B Failed  
The secondary power supply is no longer providing DC power to the control board and CAN options.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
PWR SPLY S1 AC FAIL  
Power Supply Source 1 AC Failed  
The AC input power to the power supplies from Source 1 has failed. The power supplies are now operating on  
AC power from Source 2. The AC input from Source 1 is still good.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
PWR SPLY S2 AC FAIL  
Power Supply Source 2 AC Failed  
The AC input power to the power supplies from Source 2 has failed.  
The power supplies are now operating on AC power from Source 1. The AC input from Source 2 is still good.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
PWR SPLY LOGIC FAIL  
Power Supply Module Failed  
The power supply logic module contained in the primary power supply has failed.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, is so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
OUT VOLT SENSE FAIL  
Output Voltage Sense Module Failed  
The module contained on the snubber monitoring the output voltage has failed.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
S1 VOLT SENSE FAIL  
Source 1 Voltage Sense Module Failed  
The module contained on the snubber monitoring the input voltage from Source 1 has failed.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S2 VOLT SENSE FAIL  
Source 2 Voltage Sense Module Failed  
The module contained on the snubber monitoring the input voltage from Source 2 has failed.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the STS2/PDU system  
from a terminal, type CA and press RETURN on your keyboard.  
S1 SCR SENSE FAIL  
Source 1 SCR Sense Module Failed  
The module contained on the snubber monitoring the SCRs for Source 1 has failed.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the STS2/PDU system  
from a terminal, type CA and press RETURN on your keyboard.  
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Event Message Help Text  
S2 SCR SENSE FAIL  
Source 2 SCR Sense Module Failed  
The module contained on the snubber monitoring the SCRs for Source 2 has failed.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the STS2/PDU system  
from a terminal, type CA and press RETURN on your keyboard.  
S1 CURR SENSE FAIL  
Source 1 Current Sense Failure  
The module monitoring the current from Source 1 has failed. This module is contained on the left side gate  
driver board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Events Log, is so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the STS2/PDU system  
from a terminal, type CA and press RETURN on your keyboard.  
S2 CURR SENSE FAIL  
Source 2 Current Sense Failure  
The module monitoring the current from Source 2 has failed. This module is contained on the right side gate  
driver board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Events Log, is so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the STS2/PDU system  
from a terminal, type CA and press RETURN on your keyboard.  
S1 GATE DRIVE FAIL  
Source 1 Gate Drive Failure  
The gate drive module for an SCR for Source 1 has failed. This module is contained on the right side gate  
driver board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the STS2/PDU system  
from a terminal, type CA and press RETURN on your keyboard.  
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Event Message Help Text  
S2 GATE DRIVE FAIL  
Source 1 Gate Drive Failure  
The gate drive module for an SCR for Source 2 has failed. This module is contained on the left side gate driver  
board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
INTERNAL COMM FAIL  
Internal CAN Communications Failed  
Communications have failed in the CAN bus between the control board and the touch screen control.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
CB1 SHUNT TRIP FAIL  
Circuit Breaker 1 Shunt Trip Failure  
Circuit Breaker 1 failed to trip open when the control issued a command for the circuit breaker to trip.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
CB2 SHUNT TRIP FAIL  
Circuit Breaker 2 Shunt Trip Failure  
Circuit Breaker 2 failed to trip open when the control issued a command for the circuit breaker to trip.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
EQUIPMENT FAN FAILURE  
Equipment Fan Failure  
One of the equipment fans has failed.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
INPUT 1 SURGE FAILURE  
Input 1 Surge Failure  
Source 1 input surge suppression module has failed.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
INPUT 2 SURGE FAILURE  
Input 2 Surge Failure  
Source 2 input surge suppression module has failed.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
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Event Message Help Text  
HEAT SINK OVERTEMP  
Heat Sink Over Temperature  
The system heat sink temperature has exceeded the design limits.  
Take immediate steps to cool the unit. Remove obstructions from the air inlet in the front of the unit. Remove  
and replace the air filter behind the front door. A standard furnace filter can be used.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
EQUIPMENT OVERTEMP  
Equipment Over Temperature  
Cabinet has exceeded the recommended temperature.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
S1 UV  
Source 1 Under Voltage (fast detection).  
The input voltage from Source 1 dropped below a set percentage of the nominal voltage, as set in the Fast UV  
setpoint under the User Settings. An S1 Fail alarm was also issued and source transfer has been inhibited.  
The load of the STS2/PDU has been transferred to Source 2.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S1 UV (RMS)  
Source 1 Under Voltage (slow detection).  
The input voltage from Source 1 remained below a set percentage of the nominal voltage for a designated  
period, as set in the Slow UV Setting and Slow UV Detection Delay setpoints configured under the User Set-  
tings. An S1 Fail alarm was also issued and source transfer has been inhibited.  
The load of the STS2/PDU has been transferred to Source 2.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The alarm is latched and must be reset after the voltage returns to the nominal voltage. If the Reset option is  
not configured for AUTO (automatic reset), then the reset action must be done manually. When the voltage is  
within acceptable parameters, touch the RESET button on the touch screen. If you are accessing the unit from  
a terminal, type CA and press RETURN on your keyboard.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
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Event Message Help Text  
S1 OV  
Source 1 Over Voltage.  
The input voltage from Source 1 exceeded a set percentage of the nominal voltage, as set in the OV Setting  
and OV Detection Delay setpoints configured under the User Settings. An S1 Fail alarm was also issued and  
source transferhas been inhibited.  
The load of the STS2/PDU has been transferred to Source 2.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S1 OF/UF  
Source 1 Over Frequency/Under Frequency  
The frequency for Source 1 is running outside the acceptable operating range, as set in the Frequency Trip  
Point under User Settings. An S1 Fail alarm was also issued and source transfer has been inhibited.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S1 FAIL  
Source 1 Failure  
Source 1 has failed due to under voltage (UV), over voltage (OV) or from running over or under frequency (OF/  
UF). This alarm is a companion to S1 UV, S1 UV (RMS), S1 OV and S1 OF/UF.  
The load of the STS2/PDU has been transferred to Source 2.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event has been written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S2 UV  
Source 2 Under Voltage (fast detection).  
The input voltage from Source 2 dropped below a set percentage of the nominal voltage, as set in the Fast UV  
setpoint under the User Settings. An S2 Fail alarm was also issued and source transfer has been inhibited.  
The load of the STS2/PDU has been transferred to Source 1.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
S2 UV (RMS)  
Source 2 Under Voltage (slow detection).  
The input voltage from Source 2 remained below a set percentage of the nominal voltage for a designated  
period, as set in the Slow UV Setting and Slow UV Detection Delay setpoints configured under the User Set-  
tings. An S2 Fail alarm was also issued and source transfer has been inhibited.  
The load of the STS2/PDU has been transferred to Source 1.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The alarm is latched and must be reset after the voltage returns to the nominal voltage. If the Reset option is  
not configured for AUTO (automatic reset), then the reset action must be done manually. When the voltage is  
within acceptable parameters, touch the RESET button on the touch screen. If you are accessing the unit from  
a terminal, type CA and press RETURN on your keyboard.  
This event was written to the Event Log, if so configured.  
S2 OV  
Source 2 Over Voltage.  
The input voltage from Source 2 exceeded a set percentage of the nominal voltage, as set in the OV Setting  
and OV Detection Delay setpoints configured under the User Settings. An S2 Fail alarm was also issued and  
source transfer has been inhibited.  
The load of the STS2/PDU has been transferred to Source 1.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S2 UF/OF  
Source 2 Under Frequency/Over Frequency  
The frequency for Source 2 is running outside the acceptable operating range, as set in the Frequency Trip  
Point under User Settings. An S2 Fail alarm was also issued and source transfer has been inhibited.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
S2 FAIL  
Source 2 Failure  
Source 2 has failed due to under voltage (UV), over voltage (OV) or running with an over or under frequency  
(OF/UF).  
This alarm is a companion to S2 UV, S2 UV (RMS), S2 OV and S2 OF/UF.  
The load of the STS2/PDU has been transferred to Source 1.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S1 OVERCURRENT  
Source 1 Overcurrent  
STS2/PDU is running on Source 1 and an overload condition has occurred on one or more phases.  
Note: The overload setpoint is a single fixed number—101%. An overload condition is detected when the mea-  
sured load current is equal to or greater than the setpoint.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S2 OVERCURRENT  
Source 1 Overcurrent  
STS2/PDU is running on Source 2 and an overload condition has occurred on one or more phases.  
Note: The overload setpoint is a single fixed number—101%. An overload condition is detected when the mea-  
sured load current is equal to or greater than the setpoint.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
S1 I-PEAK  
Current Peak on Source 1  
The peak current from Source 1 has exceeded the setpoint as defined in the I-PK Xfer Lockout setting under  
User Settings.  
Transferring to Source 2 has been inhibited.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
If this alarm is configured to automatically reset under the setpoints for User Settings, the alarm clears itself  
when the I-Peak condition clears.  
If this alarm is set for manual reset mode, the alarm continues to show as active after the current returns to  
nominal, still inhibiting transfers. You will need to manually reset the alarm. If configured to be a latching alarm,  
press RESET on the display. If you are accessing the unit from a terminal, type CA and press RETURN on  
your keyboard.  
The alarm has triggered a message to be sent to the modem, if so configured.  
S2 I-PEAK  
Current Peak on Source 2  
The peak current from Source 2 has exceeded the setpoint as defined in the I-PK Xfer Lockout setting under  
User Settings.  
Transferring to Source 1 has been inhibited.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
If this alarm is configured to automatically reset under the setpoints for User Settings, the alarm clears itself  
when the I-Peak condition clears.  
If this alarm is set for manual reset mode, the alarm continues to show as active after the current returns to  
nominal,  
still inhibiting transfers. You will need to manually reset the alarm. If configured to be a latching alarm, press  
RESET on the display. If you are accessing the unit from a terminal, type CA and press RETURN on your key-  
board.  
The alarm has triggered a message to be sent to the modem, if so configured.  
SOURCES OUT OF SYNC  
Sources out of synchronization.  
The phase difference between Source 1 and Source 2 has exceeded the deviation as set for MANUAL MAX  
XFER PHASE ANGLE under User Settings.  
A manual transfer cannot take place while the sources are not synchronized.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
LOAD ON ALT SOURCE  
STS2/PDU load on the alternate source.  
The Static Transfer Switch 2 Power Distribution Unit is running on the alternate power source. Check the Event  
Log to determine the reason for the transfer from the preferred source.  
Another event has caused the system to transfer to the alternate source. The system returns the load to the  
preferred source either automatically or manually, depending on how the system is configured.  
In automatic reset mode, the STS2/PDU automatically retransfers to the preferred source after the causal con-  
dition clears.  
In manual reset mode, the system remains on the alternate source after the causal event clears until you select  
RESET from the touchscreen or enter CA (Clear Alarms) from a service terminal.  
NOTE  
Pressing the RESET button returns the unit to the preferred source. Ensure that the condition  
that triggered the switch has been rectified before returning to the preferred source.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
AUTO REXFER INHIBIT  
Automatic Retransfer Inhibited.  
The system made five transfers from the preferred source to the alternate source in the last five minutes. As a  
result, automatic retransfers back to the preferred source is now disabled.  
To clear this alarm condition, assign the alternate source as the preferred source.  
This alarm also is cleared if the unit transfers to the preferred source due to an alternate source AC volt failure  
(i.e., an emergency transfer.)  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
CB1 (S1) OPEN  
Circuit Breaker 1 (for Source 1) Open  
Circuit Breaker 1 is not closed. CB1 is only assigned to Source 1.  
Check that the Circuit Breaker 1 switch is in the desired position.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
CB2 (S2) OPEN  
Circuit Breaker 2 (for Source 2) Open  
Circuit Breaker 2 is not closed. CB1 is only assigned to Source 2.  
Check that the Circuit Breaker 2 switch is in the desired position.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
CB4 (S1 BYP) CLOSED  
Circuit Breaker 4 (Source 1 Bypass Breaker) Closed  
Circuit breaker 4 is not open. The input from Source 1 is bypassing the Static Transfer Switch 2 Power Distribu-  
tion Unit.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
CB5 (S1 BYP) CLOSED  
Circuit Breaker 5 (Source 2 Bypass Breaker) Closed  
Circuit breaker 5 is not open. The input from Source 2 is bypassing the Static Transfer Switch 2 Power Distribu-  
tion Unit.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
CB3 (OUTPUT) OPEN  
Circuit Breaker 3 (Output breaker) Open  
Circuit breaker 3 is not closed. This circuit breaker is assigned to the output load. The power flow to the load  
cannot flow through the Static Transfer Switch 2 Power Distribution Unit.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
CB3A (OUTPUT) OPEN  
Circuit Breaker 3A (Output breaker) is Open (Optional)  
Circuit breaker 3A is not closed. This circuit breaker is assigned to the output load. The power flow to the load  
cannot flow through the Static Transfer Switch 2 Power Distribution Unit.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S1 PHASE ROT ERROR  
Source 1 Phase Rotation Error  
A phase rotation error condition exists on Source 1. Check the phase sequence (ABC) of Source 1.  
Transferring to Source 1 has been inhibited.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
S2 PHASE ROT ERROR  
Source 2 Phase Rotation Error  
A phase rotation error condition exists on Source 2. Check the phase sequence (ABC) of Source 2.  
Transferring to Source 1 has been inhibited.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
TRANSFER INHIBITED  
Transfer Inhibited  
Uninterrupted transfer between sources is inhibited due to input source failure, sources out of sync, switch fail-  
ure or the unit is in bypass mode.  
Check the Event Log for the event or events that may have caused the alarm.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
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Event Message Help Text  
OUTPUT UV  
Output Undervoltage  
The voltage being supplied to the load has dropped below the acceptable nominal voltage. Check the input  
voltage from both sources.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
HISTORY LOG FROZEN  
History Log Frozen  
Both History Logs have been written and no more history logs can be written without clearing one of the logs.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
INPUT 1 OVERVOLTAGE  
Input 1 Overvoltage  
Source 1 is over voltage.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
INPUT 1 UNDERVOLTAGE  
Input 1 Undervoltage  
Source 1 is under voltage.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
137  
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Event Message Help Text  
INPUT 2 OVERVOLTAGE  
Input 2 Overvoltage  
Source 2 is over voltage.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
INPUT 2 UNDERVOLTAGE  
Input 2 Undervoltage  
Source 2 is under voltage.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
LOAD OVERCURRENT  
Load Overcurrent  
Output is over current.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
GROUND OVERCURRENT  
Ground Overcurrent  
Ground is over current.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event and the system status surrounding it have been written to a History Log if the History Logs were not  
already full. This event was also written to the Event Log, if so configured.  
138  
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Event Message Help Text  
NEUTRAL OVERCURRENT  
Neutral Overcurremt  
Neutral is over curremt.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was also written to the Event Log, if so configured.  
LOAD VOLTAGE THD  
Load Voltage Total Harmonic Distortion  
Voltage THD has exceeded the set limit.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was also written to the Event Log, if so configured.  
INPUT 1 CB6 OPEN  
Input 1 CB6 Open  
Source 1 input Circuit Breaker 6 is open.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was also written to the Event Log, if so configured.  
INPUT 2 CB7 OPEN  
Input 2 CB7 Open  
Source 2 Input Circuit Breaker 7 is open.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was also written to the Event Log, if so configured.  
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Event Message Help Text  
INPUT 1 OF/UF  
Input 1 Over Frequency/Under Frequency  
Source 1 is over frequency/under frequency  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was also written to the Event Log, if so configured.  
INPUT 2 OF/UF  
Input 2 Over Frequency/Under Frequency  
Source 2 is over frequency/under frequency.  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
This event was also written to the Event Log, if so configured.  
INPUT CONTACT #1  
Input Contact Isolator #1  
Occurrence of the indicated external event has been detected by Input Contact Isolator #1 of the Open Comms  
Digital Input option board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event, with its assigned name, was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
INPUT CONTACT #2  
Input Contact Isolator #2  
Occurrence of the indicated external event has been detected by Input Contact Isolator #2 of the Open Comms  
Digital Input option board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event, with its assigned name, was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
140  
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Event Message Help Text  
INPUT CONTACT #3  
Input Contact Isolator #3  
Occurrence of the indicated external event has been detected by Input Contact Isolator #3 of the Open Comms  
Digital Input option board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event, with its assigned name, was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
INPUT CONTACT #4  
Input Contact Isolator #4  
Occurrence of the indicated external event has been detected by Input Contact Isolator #4 of the Open Comms  
Digital Input option board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event, with its assigned name, was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
INPUT CONTACT #5  
Input Contact Isolator #5  
Occurrence of the indicated external event has been detected by Input Contact Isolator #5 of the Open Comms  
Digital Input option board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event, with its assigned name, was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
INPUT CONTACT #6  
Input Contact Isolator #6  
Occurrence of the indicated external event has been detected by Input Contact Isolator #6 of the Open Comms  
Digital Input option board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event, with its assigned name, was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
141  
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Event Message Help Text  
INPUT CONTACT #7  
Input Contact Isolator #7  
Occurrence of the indicated external event has been detected by Input Contact Isolator #7 of the Open Comms  
Digital Input option board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event, with its assigned name, was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
INPUT CONTACT #8  
Input Contact Isolator #8  
Occurrence of the indicated external event has been detected by Input Contact Isolator #8 of the Open Comms  
Digital Input option board.  
Press SILENCE on the touch screen to turn off the audible alarm, if so configured. If you are accessing the  
STS2/PDU system from a terminal, type SH and press RETURN on your keyboard to turn off the audible  
alarm.  
The event, with its assigned name, was written to the Event Log, if so configured.  
The alarm has triggered a message to be sent to the modem, if so configured.  
If configured to be a latching alarm, press RESET on the display. If you are accessing the unit from a terminal,  
type CA and press RETURN on your keyboard.  
CONFIG MODIFIED  
Configuration Modified  
A setpoint has been updated and saved.  
The event was written to the Event Log, if so configured.  
PASSWORD CHANGED  
Access Password Changed  
The password for accessing the HMI (touch screen) options has been updated and saved.  
The event was written to the Event Log, if so configured.  
TIME REPROGRAMMED  
System Time Reprogrammed  
The system’s time setting has been updated and saved.  
The event was written to the Event Log, if so configured.  
DATE REPROGRAMMED  
System Date Reprogrammed  
The system’s date setting has been updated and saved.  
The event was written to the Event Log, if so configured.  
EVENT LOG CLEARED  
Event Log Cleared  
All past alarms and faults are no longer recorded in the system’s event log.  
This event was written to the Event Log, if so configured.  
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Event Message Help Text  
HIST LOGS CLEARED  
History Logs Cleared  
Both History Logs have been erased and the logs are now available to record future events.  
The event was written to the Event Log, if so configured.  
TRANSFER COUNTER CLEARED  
Transfer Counter Cleared  
Transfer counter reset to 0  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was also written to the Event Log, if so configured.  
KW-HRS COUNTER CLEARED  
KW-HRS counter cleared  
KW-Hrs counter reset to 0  
Contact technical support; in the United States, call 1-800-LIEBERT (1-800-543-2378). Outside the 48 contigu-  
ous United States contact Liebert Global Services, if available in your area. For international areas not covered  
by Liebert Global Services, the Liebert authorized distributor can provide technical support.  
This event was also written to the Event Log, if so configured.  
143  
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Maintenance  
16.0 MAINTENANCE  
WARNING  
!
Only qualified service personnel should perform maintenance on the STS2/PDU.  
Lethal voltages exist inside the unit during normal operation.  
The unit is supplied by multiple AC power sources. Disconnect and lock out all power sources  
before working inside unit.  
Minimal periodic maintenance of the STS2/PDU is required. As with all electrical distribution compo-  
nents, the system should be regularly inspected for electrical connection integrity, signs of excessive  
temperatures, dirt accumulation and proper system operation.  
16.1 Proper Tightening of Nuts and Bolts  
The recommended tightening torque for all nuts and bolts is as shown below, unless otherwise  
labeled. All power connections are designed to remain at proper torque throughout the lifetime of the  
unit.  
Table 29 Torque tightening  
Grade 5 - Imperial  
Grade 8.8 - Metric  
Electrical Connections with  
Belleville Washers  
in-lb  
(pound-inch)  
N-m  
(Newton-meter)  
in-lb  
(pound-inch)  
N-m  
(Newton-meter)  
Bolt Shaft Size  
10-32  
25  
53  
3
35  
80  
4
1/4-20  
6
9.0  
5/16-18  
3/8-16  
107  
192  
428  
12  
22  
48  
180  
240  
480  
20.4  
27.1  
54.3  
1/2-13  
Table 30 Branch circuit breakers  
in-lb  
N-m  
(Newton-meter)  
Current Rating  
Up to 30 Amp  
40 to 100 Amp  
(pound-inch)  
35  
45  
4.0  
5.1  
16.2 Testing the STS2/PDU  
The STS2/PDU includes comprehensive system alarms and fault detection to identify operational  
problems. To increase the degree of confidence of proper system operation, periodic transfer tests can  
be easily performed. For instructions for changing the preferred source and switching sources, see  
16.3 Changing the Air Filter  
A standard furnace filter is installed behind the air intake in the front door. The air intake allows air  
to circulate to cool the unit. Replace the filter when it becomes dirty and impedes air flow. The fre-  
quency of changing or cleaning the filter depends on the location in which the unit is located. The size  
of the filter is 1 x 25 x 25 in. (254 x 635 x 635mm).  
144  
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Customer Settings  
17.0 CUSTOMER SETTINGS  
17.1 Programmable Relay Board Settings  
The optional programmable relay board (PRB) has eight channels to report events to an external  
device. Up to ten (10) events can be programmed to each channel. See 6.1 - Programmable Relay  
Board for more information on the PRB.  
If your STS2/PDU has the PRB option installed, list the settings below for future reference. If control  
power is lost in the STS2/PDU, the settings are not saved.  
Table 31 Programmable relay board settings record  
Channel 1  
Channel 2  
Channel 3  
Channel 4  
Channel 5  
Channel 6  
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Customer Settings  
Table 31 Programmable relay board settings record  
Channel 7  
Channel 8  
Channel 9  
Channel 10  
PRB Notes  
17.2 Input Contact Isolator Settings  
The Input Contact Isolator board (ICI) provides an STS2/PDU module interface for up to eight exter-  
nal user alarm or message inputs to be routed through the Static Transfer Switch 2 Power Distribu-  
tion Unit’s alarm network. See 6.2 - Input Contact Isolator Board for more information on the ICI.  
If your STS2/PDU has the ICI option installed, list the settings below for future reference. If control  
power is lost in the STS2/PDU, the settings are not saved.  
Table 32 Input contact isolator settings record  
Channel 1  
Channel 2  
Channel 3  
Channel 4  
Channel 5  
Channel 6  
Channel 7  
Channel 8  
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POWER DISTRIBUTION  
STS2/PDU  
INSTALLATION, OPERATION & MAINTENANCE MANUAL  
The Company Behind the Products  
Technical Support/Service  
Web Site  
With over a million installations around the globe,  
Liebert is the world leader in computer protection  
systems. Since its founding in 1965, Liebert has  
developed a complete range of support and  
protection systems for sensitive electronics:  
www.liebert.com  
Monitoring  
800-222-5877  
Outside the US: 614-841-6755  
Environmental systems—close-control air  
conditioning from 1 to 60 tons  
Single-Phase UPS  
800-222-5877  
Power conditioning and UPS with power  
ranges from 300 VA to more than 1000 kVA  
Integrated systems that provide both  
environmental and power protection in a  
single, flexible package  
Monitoring and control—from systems of any  
size or location, on-site or remote  
Service and support through more than 100  
service centers around the world and a 24/7  
Customer Response Center  
Outside the US: 614-841-6755  
Three-Phase UPS  
800-543-2378  
Environmental Systems  
800-543-2778  
Outside the United States  
614-888-0246  
While every precaution has been taken to ensure  
the accuracy and completeness of this literature,  
Liebert Corporation assumes no responsibility and  
disclaims all liability for damages resulting from  
use of this information or for any errors or  
omissions.  
Locations  
United States  
1050 Dearborn Drive  
P.O. Box 29186  
Columbus, OH 43229  
Italy  
Via Leonardo Da Vinci 8  
Zona Industriale Tognana  
35028 Piove Di Sacco (PD)  
+39 049 9719 111  
© 2003 Liebert Corporation  
All rights reserved throughout the world.  
Specifications subject to change without notice.  
® Liebert and the Liebert logo are registered  
trademarks of Liebert Corporation. All names  
referred to are trademarks or registered  
trademarks of their respective owners.  
Fax: +39 049 5841 257  
Asia  
23F, Allied Kajima Bldg.  
138 Gloucester Road  
Wanchai  
Hong Kong  
+852 2 572 2201  
Fax: +852 2 831 0114  
SL-20730 (2/04) Rev. 0  
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