Trane Refrigerator RTAA 70 125 TON User Manual

Diagnostic  
Troubleshooting  
Repair  
Series R®  
70-125 Ton Air-Cooled and Water-Cooled  
Rotary Liquid Chillers  
Model  
RTAA 70-125 Ton  
RTWA 70-125 Ton  
RTUA 70-125 Ton  
August 2005  
RLC-SVD03A-EN  
© American Standard Inc. 2005  
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Contents  
Compressor Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
Checkout Procedure for the Slide Valve and Load/  
Checkout Procedure for Step Load Solenoid Valve  
LonTalk® Communications Interface - Chillers Module  
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General Information  
The Unit Control Modules (UCMs) described in this troubleshooting guide  
provide a microprocessor based refrigeration control system, intended for  
use with Trane 70-125 ton helical rotor chillers. Six types of modules are  
used, and throughout this publication will be referred to by their abbreviations  
or their Line Wiring Drawing Designations, see Table 1.  
Table 1  
Unit Control Module Designations  
Line Drawing Controller Name  
Abbrev.  
CPM  
Designation  
Chiller Module  
1U2  
Options Module  
CSR  
1U3  
Expansion Valve Module  
Compressor Module  
EXV  
1U4 & 1U5  
1U6  
MCSP A & B  
CLD  
Clear Language Display  
1U7  
Interprocessor  
IPCB  
Communications Bridge  
(Remote Display Buffer)  
Service Philosophy  
With the exception of the fuses, no other parts on or within the modules are  
serviceable. The intent of the troubleshooting is to determine which module  
is potentially at fault and then to confirm a module problem. This is done  
either through voltage or resistance measurements at the suspected input or  
output terminals or by checking related wiring and external control devices  
(connectors, sensors, transformers, contactors etc.) in a process of elimi-  
nation. Once a problem has been traced to a module, the module can be  
easily replaced using only basic tools. In general, all dip switch settings of the  
replaced modules should be copied onto the replacement module's dip  
switches before applying control power. CPM replacement is more involved  
as there are numerous configuration and set-up items that must be  
programmed at the Clear Language Display in order to insure proper unit  
operation.  
It is helpful to include with the return of a module, a brief explanation of the  
problem, sales office, job name, and a contact person for possible follow-up.  
The note can be slipped into the module enclosure. Early and timely  
processing of Field Returns allows for real measurements of our product  
quality and reliability, providing valuable information for product improvement  
and possible design changes.  
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General Information  
System Description  
The CPM is the master module and coordinates operation of the entire  
system. One is used per chiller. The MCSP is a compressor protection  
module with one being used for each of the compressors in the chiller. The  
EXV is the expansion valve controller module which controls two Electronic  
Expansion Valves. There is one valve on each of the two refrigeration circuits.  
The CLD is a two line, 40 character alphanumeric interface to the system. It  
allows the operator to read operating and diagnostic information, as well as  
change control parameters. The Interprocessor Communications Bridge  
(IPCB) provides an extension of the IPC link to the Remote Clear Language  
Display, while protecting the integrity of the IPC communications link  
between the local modules.  
The CSR is an optional communications module which allows for communica-  
tions between the chiller and a remote building automation system (i.e.  
Tracer, Tracer Summit, Generic BAS).  
All modules in the system communicate with each other over a serial inter-  
processor communications bus (IPC) consisting of a twisted wire pair “daisy  
chain” link and RS485 type signal levels and drive capability. Multiple modules  
of the same type (i.e. MCSPs) in an operating system are differentiated by  
address dip switches.  
All the modules operate from 115VAC, 50 or 60Hz power and each have their  
own internal step-down transformer and power supply. Each is individually  
fused with a replaceable fuse. The modules also are designed to segregate  
their high and low voltage terminals by placing the high voltage on the right  
side of the module and the low voltage on the left. When stacked, segre-  
gation is maintained.  
In addition to the modules, there are a number of “system level” compo-  
nents that are closely associated with the modules. These components were  
specifically designed and/or characterized for operation with the modules. For  
this reason, the exact Trane part must be used in replacement.  
System Level Components  
Description  
The following is a list of all the components that may be found connected to  
the various modules.  
Transformer, Under/Over voltage  
Current Transformer - Compressor  
Evap EntlLvg Water Temp Sensor Pair  
Sat Evap/Cprsr Suc Rfgt Temp. Sensor Pair  
Sat Cond RfgtIOil Temp Sensor Pair  
Outdoor Air Temperature Sensor  
Zone Temp Sensor  
Connector (UCM mating connectors)  
Connector Keying Plug  
Electronic Expansion Valve  
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General Information  
High Pressure Cutout Switch  
Low Pressure Cutout Switch  
Variable Speed Fan Drive  
Motor Temperature Thermostats  
Slide Valve Load/Unload Solenoids  
Step Load Solenoid Valve  
Chiller Module (CPM) IU1  
The CPM module performs machine (chiller) level control and protection  
functions. Only one CPM is present in the chiller control system. The CPM  
acts as the master controller to the other modules, running top level machine  
control algorithms, initiating and controlling all inter-module communication  
over the IPC, and providing parameters and operational requests (i.e. loading  
and unloading, starting and stopping) to the other modules in the system via  
the IPC. The CPM also contains nonvolatile memory, which allows it to  
remember configuration and set-up values, setpoints, historical diagnostics  
etc. for an indefinite period of time following a power loss. Direct hard wired  
I/O associated with the CPM includes low voltage analog inputs, low voltage  
binary inputs, 115 VAC binary inputs and 115 VAC (rated) relay outputs. See  
Compressor Module (MCSP) 1U4 and 1U5  
The MCSP module employs the input and output circuits associated with a  
particular compressor and refrigeration circuit. Two MCSP modules are used  
in the UCM system, one for each compressor. Included are low voltage  
analog and digital circuits, 115 VAC input, and 115 VAC output switching  
devices. The output switching devices associated with the compressor motor  
controlling function are contained in this module. The outputs of this module  
control one compressor motor stop/start contactor, one compressor motor  
transition contactor, one oil heater, three solenoid valves (compressor load,  
compressor unload, step loader), and up to four fan motor contactors or  
groups of contactors. Refer to the chiller's line wiring diagrams for details. Dip  
switches are provided for redundant programming of the compressor current  
overload gains, and for unique IPC address identification during operation.  
Inputs to this module include motor temperature thermostats, thermisters,  
page 72 for details.  
Expansion Valve Module (EXV) 1U3  
The EXV module provides power and control to the stepper motor driving the  
electronic expansion valves of the chiller. Each module handles two valves,  
one in each refrigeration circuit.  
Input to the EXV Module is provided by four temperature sensors (two per  
refrigeration circuit). The sensors are located in the respective refrigeration  
circuits of the chiller and sense Saturated Evaporator and Suction tempera-  
tures and calculate the superheat temperatures. High level operational  
commands as well as superheat setpoints are received by the EXV Module  
over the IPC from the CPM module to modulate the EXV's.  
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General Information  
Real time data for temperatures, diagnostics and control algorithms etc. are  
made available to the CPM and the other modules for display and for input to  
page 58 for details.  
Options Module (CSR) 1U2  
The CSR module is an optional part of the system and employs communica-  
tions circuits for interface to Trane Building Automation Systems, done  
through 1C17. The CSR also provides inputs for hard wired external setpoints  
and reset functions. Included are low voltage analog and digital input circuits.  
Clear Language Display (CLD) 1U6  
The CLD Module provides an operator interface to the system, through a two  
line, 40 character alphanumeric display. Three reports may be displayed and  
various operating parameters may be adjusted by depressing a minimal  
number of keys on the CLD. Also, chiller Start/Stop functions may be  
performed at this keypad. See Clear Language Display (CLD) 1U6 Keypad  
Overview on page 42 for details.  
Interprocessor Communication Bridge (IPCB) 1U7  
The IPCB module allows connection of a Remote Clear Language Display  
module to the UCM, for distances of up to 1500 feet. The Remote Clear  
Language Display communicates with the UCM, utilizing the same IPC  
protocol, and provides most of the same functions as the local CLD. The IPCB  
then serves to protect the UCM's IPC if wires to the Remote CLD become  
shorted or broken. See Section 2 and on page 75 for details.  
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Interprocessor Communications  
The respective modules communicate with each other via an InterProcessor  
Communication link (IPC). The IPC allows the modules to work in a coordi-  
nated manner with the CPM directing overall chiller operation while each  
module handles specific subfunctions. This IPC link is integral and necessary  
to the operation of the Unit Controls and should not be confused with the  
Optional ICS (Integrated Comfort System) communication.  
In the IPC communication protocol scheme, the CPM acts as the initiator and  
the arbitrator of all module communication. The CPM essentially requests all  
the possible “packets” of information from each module in turn, (including  
itself), in a predefined serial sequence. The other modules act as  
“responders” only and cannot initiate communication. Modules which are not  
currently responding to a specific request, can listen to the data and thus,  
indirectly, they communicate with each other. It is helpful to remember when  
troubleshooting that a module must be able to hear a request for its infor-  
mation from the CPM, or it will not talk.  
The link is non-isolated, which means that a good common ground between  
all the modules is necessary for trouble-free operation (provided by the  
module enclosures' mounting using star washers). Also, the link requires  
consistent polarity on all of the module interconnections. Connections  
between modules are made at the factory, using unshielded #18 gauge  
twisted pair cable terminated into a 4-position MTA type connector (orange  
color code). This connector is plugged onto the 4 pin IPC connection jack  
designated as J1, located in the upper left corner of the PC board edge on all  
of the modules. The 4 pins actually represent 2 pairs of communications  
terminals (J1-1 (+) internally connected to J1-3, and J1-2 (-) internally  
connected to J1-4) to allow for easy daisy chaining of the bus.  
IPC Diagnostics  
The modules, in order to work together to control the chiller, must constantly  
receive information from each other over the IPC. Failure of certain modules  
to communicate or degradation of the communication link, could potentially  
result in chiller misoperation. To prevent this situation, each module monitors  
how often it is receiving information from designated other modules. If a  
module fails to receive certain other module's transmitted data over a 15  
second time period it will:  
1. On its own, take specific action to safely shut-down (or to default) its con-  
trolled loads.  
2. Report a diagnostic to the CPM (over the IPC link).  
The CPM (if it properly receives such) will then report and display the  
diagnostic on the Clear Language Display accordingly. The diagnostic will:  
identify which module is reporting the communication problem and  
identify which module was to have sent the missing information.  
The CPM itself will then send out further commands to the other modules to  
shutdown or take default actions as the particular case may warrant.  
All IPC diagnostics are displayed in the Clear Language Display's diagnostics  
section. For example, “Chiller Mod indicating Options Mod Comm Failure”  
indicates that the CPM Module has detected a loss of IPC communication  
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Interprocessor Communication  
from the Options Module. When some problem exists with the IPC link or a  
module fails, it is not uncommon for more than one of these IPC diagnostics  
to be displayed. Note that only those diagnostics that are indicated to be  
active currently exist. All other historic diagnostics should be disregarded for  
the purpose of the following troubleshooting discussion. See RTAA-IOM-4 for  
a complete listing of diagnostics.  
Troubleshooting Modules Using IPC Diagnostics  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
Communication problems can result from any of the following:  
1. Improperly set IPC address dip switches  
2. Opens or shorts in the twisted pair IPC wiring or connectors  
3. Loss of power to a module  
4. Internal module failure  
5. Improper connections on terminal J2  
6. High levels of EMI (Electro-Magnetic Interference)  
7. Module specific function selected without the Options Module.  
These are discussed in more detail in the following paragraphs.  
1. Improperly set IPC address dip switches:  
This could result in more than one module trying to talk at the same time,  
or cause the mis-addressed module to not talk at all. Only the MCSP and  
the EXV modules have IPC address dip switches, found in the upper left  
hand portion of the Module labeled as SW-1. The proper dip switch set-  
ups are shown in Table 2.  
2. Opens or shorts in the twisted pair IPC wiring or connectors:  
One or more modules may be affected by an open or a short in the IPC  
wiring, depending on the location of the fault in the daisy chain. The dia-  
gram below shows the daisy chain order and is helpful in diagnosis of an  
open link.  
Extreme care should be used in making any dip switch changes or when  
replacing MCSP modules. “Swapping” of addresses on the MCSPs  
cannot be detected by the communication diagnostics discussed above  
and serious chiller misoperation will result.  
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Interprocessor Communication  
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IPC Link Order For 70-125 Ton RTAA  
10  
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Interprocessor Communication  
.Table 2  
IPC Address Dip Switch (SW1) Settings for MCSP an EXV Modules  
MODULE  
DESIG.  
CONTROLLING  
DIP SWITCH SETTING  
SW1-1  
SW1-2  
MCSP A”  
MCSP “B”  
EXV  
1U4  
1U5  
1U3  
COMPRESSOR A  
COMPRESSOR B  
CKTS. 1 & 2  
OFF  
OFF  
OFF  
OFF  
ON  
OFF  
3. Loss of power to a module:  
Generally a power loss to a particular module will only affect communica-  
tions with that module. The module can usually be identified by analysis  
of the IPC diagnostics. (When the display is blank, check power at the  
CLD). Loss of power can most directly be diagnosed by measuring the  
AC voltage at the top of the fuse with respect to the neutral of the power  
connection (pins 4 or 5) on the terminal just below the fuse:  
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Module Fuse and Power Connection, Except CLD  
4. Internal module failure:  
Internal module failures usually result only in communication loss to the  
failed module, but could, in some cases, affect all the modules because  
the failed module may “lock up” the IPC bus and prevent all communica-  
tions. The former can be identified by analyzing all of the active IPC diag-  
nostics. The latter can be identified in a process of elimination, whereby  
each module, in turn, is taken out of the IPC link and a jumper installed in  
its place. See Figure 3. The CPM can then be reset and the new IPC diag-  
nostics that result can be analyzed.  
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Interprocessor Communication  
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IPC Jumper For Bypassing Modules (to be inserted into MTA  
connector in place of module)  
5. Improper connections to terminal J2:  
Jack J2, present on all modules except CLD, should have no connections.  
This input is for manufacturing test purposes only and any connections,  
shorts, etc. will potentially cause the module to not respond, respond to  
the wrong address, or (in the case of the CPM) fail to initiate any commu-  
nications and thus fail the entire IPC.  
6. High levels of Electro-Magnetic Interference:  
The modules and the IPC have been qualified under severe EMI (both  
radiated and conducted) and the system was determined to be immune  
to all but extremely high noise levels. Always be sure to close and latch  
the control panel cabinet doors as the panel enclosure provides signifi-  
cant shielding and is integral in the overall noise immunity of the control  
system.  
7. Module specific function selected without the Options Module:  
If any of the functions on the Options Module are selected but the  
Options Module is not present, the UCM will look for this module and  
generate an error. The Options Module functions include Chilled Water  
Reset, Ice Machine Control, External Chilled Water Setpoint, External  
Current Limit Setpoint, and Tracer/Summit Communications.  
Troubleshooting Procedure  
1. Place the CPM in “Stop. Record the active IPC diagnostics as shown in  
the Diagnostics Report of the CLD. The communication failure diagnos-  
tics and their meanings are shown in IPC Diagnostics of the RTAA-IOM-4  
manual.  
2. Determine which modules are not talking. These modules must be  
affected by one of the previously stated problems. If there is a group of  
modules not talking, suspect a wiring problem early in the daisy chain  
link. If only one module is not talking, suspect a loss of power or blown  
fuse.  
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Interprocessor Communication  
3. Determine which modules are still talking. Wiring up to these is likely to  
be OK.  
4. Try disconnecting the link or jumping out modules in the link at various  
places (use Figure 1). Reset the diagnostics and note which diagnostics  
reappear.  
Here are some examples of IPC diagnostics:  
Diagnostics present:  
Chiller Mod Indicating EXV Mod Communications  
Cprsr A Indicating EXV Mod Communications  
Cprsr B Indicating EXV Mod Communications  
The CPM and both MCSP modules are detecting a loss of communications  
with the EXV. Suspect power to the EXV or its fuse or a wiring problem  
downstream of the MCSP A and B modules.  
Diagnostics present:  
Chiller Mod Indicating Options Mod Communications  
Chiller Mod Indicating EXV Mod Communications  
Chiller Mod Indicating Cprsr A Communications  
Chiller Mod Indicating Cprsr B Communications  
The CPM is reporting that it cannot talk to any of the other modules. Suspect  
a shorted IPC bus or a module locking up the bus. The CPM could also be bad  
and not be sending recognizable tokens. Discriminating between these possi-  
bilities is done by disconnecting the link or jumping out modules in the link at  
various places. Refer to Item 4 in Troubleshooting Modules (Troubleshooting  
Modules Using IPC Diagnostics on page 9) for the procedure and the IPC  
Jumper for bypassing the Modules.  
Diagnostics present:  
Chiller Mod Indicating Cprsr B Communications  
EXV Mod Indicating Cprsr B Communications  
The CPM and EXV have both detected a communication loss with MCSP B.  
Suspect the address switch on MCSP B or a power/fuse problem.  
Diagnostics present:  
Chiller Mod Indicating Cprsr A Communications  
Chiller Mod Indicating Cprsr B Communications  
EXV Mod Indicating Cprsr A Communications  
EXV Mod Indicating Cprsr B Communications  
The CPM and EXV have both detected a communication loss with MCSP A  
and MCSP B. Suspect that the address switches on both modules are set to  
the same address. Wiring is probably OK since the EXV can talk to the CPM.  
Diagnostics present:  
Chiller Mod Indicating Cprsr B Communications  
Chiller Mod Indicating Cprsr A Communications  
Chiller Mod Indicating EXV Mod Communications  
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Interprocessor Communication  
The CPM has detected loss of communications with MCSP A, MCSP B,  
and EXV. Suspect an open early in the IPC link between the CPM and  
MCSP B.  
There are a large number of possible combinations of diagnostics. One must  
deduce what is causing the problem using all available information.  
If the CLD Comm link to the CPM is broken, the message is:  
No Communication, Data Not Valid  
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Temperature Sensor Checkout  
With the exception of the thermostats located in the motor windings of the  
screw compressors, all the temperature sensors used on the UCMs are  
negative temperature coefficient (NTC) thermistors. The thermistors  
employed all have a base resistance of 10 Kohms at 77F (25C) and display a  
decreasing resistance with an increasing temperature. The UCMs “read” the  
temperature by measuring the voltage developed across the thermistors in a  
voltage divider arrangement with a fixed internal resistance. The value of this  
“pull-up” resistor is different depending on the temperature range where the  
most accuracy is desired. The voltage source for this measurement is a  
closely regulated 5.0 VDC supply.  
An open or shorted sensor will cause the UCM to indicate the appropriate  
diagnostic. In most cases, an open or short will cause a CMR or MMR  
diagnostic that will result in a machine or circuit shutdown. Open or shorts on  
less critical Outdoor Air or Zone Temperature sensors will result in an  
Informational Warning Diagnostics and the use of default values for  
that parameter.  
Temperature Sensor Checkout Procedure  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
1. Measure the temperature at the sensor using an accurate thermometer.  
Record the temperature reading observed.  
2. With the sensor leads connected to the UCM and the UCM powered,  
measure the DC voltage across the sensor leads at the terminal or probe  
the back of the MTA plug.  
NOTE: Always use a digital volt-ohmmeter with 10 megohm or greater input  
impedance to avoid “loading down” the voltage divider. Failure to do so will  
result in erroneously high temperature calculations.  
3. Locate the appropriate sensor table. Table 3: Evaporator Water and  
Refrigerant Temperature Sensors, Table 4: Saturated Condenser Refriger-  
ant and Entering Oil Temperature Sensors. Then compare the tempera-  
ture in the table corresponding to the voltage reading recorded in Step 2  
with the actual temperature observed in Step 1. If the actual temperature  
measured falls within the allowable tolerance range, both the sensor and  
the UCM's temperature input circuits are operating properly. However, if  
the actual temperature is outside the allowable sensor tolerance range,  
proceed to Step 4.  
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Temperature Sensor Checkout  
4. Again measure the temperature at the sensor with an accurate thermom-  
eter; record the temperature reading observed.  
5. Remove the sensor leads from the terminal strip or unplug the respective  
MTA. Measure the resistance of the sensor directly or probe the MTA  
with a digital volt-ohmmeter. Record the resistance observed.  
6. Next, with the sensor still disconnected from the module, check the  
resistance from each of the sensor leads to the control panel chassis.  
Both readings should be more than 1 Megohm. If not, the sensor or the  
wiring to the sensor is either shorted or leaking to chassis ground and  
must be repaired.  
7. Select the appropriate sensor table and locate the resistance value  
recorded in Step 5. Verify that the temperature corresponding to this  
resistance value matches (i.e. within the tolerance range specified for  
that sensor) the temperature measured in Step 4.  
8. If the sensor temperature is out of range, the problem is either with the  
sensor, wiring, or the MTA connector (if applicable). If an MTA connector  
is used and the thermistor reads open, first try cutting off the MTA, strip-  
ping a small amount of insulation from the sensor wire's end and repeat-  
ing the measurement directly to the leads. Once the fault has been  
isolated in this manner, install a new sensor, connector or both. When  
replacing a sensor, it is easiest to cut the sensor wire near the MTA end  
and splice on a new sensor using wire nuts.  
9. A decade box can be substituted for the sensor and any sensor table  
value used to relate resistance to temperature. By removing the MTA  
plug and applying the resistance to the proper pin terminals, the tempera-  
ture, as sensed by the UCM, can be confirmed. Using the CLD menu dis-  
plays, scroll to the display of the temperature of interest.  
NOTE: All displayed temperatures are slew rate limited and only accurate  
within a specified normal range. It is therefore important to be certain that  
the temperature readings are stable and that adequate time, up to 1 minute,  
is allowed after step changes in resistance inputs are made.  
10. In all instances where module replacement is indicated, first perform the  
power supply/fuse check according to the information in the section  
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Temperature Sensor Checkout  
.
Table 3  
Sensor Conversion Data: Outdoor Air (6RT3), Entering and Leaving Evap Water Temp Matched  
Pairs (6RT7, 6RT8), and Saturated Evap and Comp Suction Refrigeration Temp (6RT9, 3B1RT5; 6RT10, 4B1RT6)  
Actual  
Temp.  
(F)  
Actual  
Resistance  
(Ohms)  
170040.3  
164313.4  
158796.5  
153482.9  
148365.0  
143432.2  
138679.6  
134098.6  
129684.9  
125428.5  
121326.1  
117369.6  
113554.9  
109876.5  
106328.1  
102904.9  
99602.3  
96416.1  
93341.6  
90374.2  
87510.3  
84745.9  
82077.1  
79500.5  
77012.3  
74609.7  
72288.8  
70047.4  
67881.9  
65790.2  
63768.7  
61815.3  
59927.8  
58103.1  
56339.6  
54634.7  
52986.4  
51392.6  
49851.6  
48360.9  
46919.2  
45524.6  
44175.6  
42870.3  
41607.6  
Thermistor  
Voltage  
(Volts DC)  
4.448  
4.434  
4.414  
4.395  
4.380  
4.360  
4.341  
4.321  
4.302  
4.282  
4.263  
4.238  
4.219  
4.194  
4.175  
4.150  
4.126  
4.106  
4.082  
4.058  
4.033  
4.004  
3.979  
3.955  
3.926  
3.901  
3.872  
3.848  
3.818  
3.789  
3.760  
3.730  
3.701  
3.672  
3.643  
3.608  
3.579  
3.550  
3.516  
3.486  
3.452  
3.418  
3.389  
3.354  
3.320  
3.286  
3.257  
3.223  
3.188  
3.154  
Actual  
Temp.  
(F)  
Actual  
Resistance  
(Ohms)  
34838.9  
33833.3  
32861.4  
31935.3  
31038.7  
30170.5  
29329.5  
28515.0  
27725.9  
26961.4  
26220.8  
25503.0  
24807.5  
24133.3  
23479.7  
22846.1  
22231.9  
21636.2  
21058.7  
20498.4  
19955.0  
19427.9  
18916.5  
18420.3  
17938.8  
17471.6  
17018.0  
16577.8  
16150.5  
15735.7  
15332.9  
14941.7  
14561.9  
14193.0  
13834.6  
13486.5  
13148.3  
12819.8  
12500.5  
12190.2  
11888.7  
11595.6  
11310.7  
11033.7  
10764.4  
10502.6  
10248.0  
10000.4  
9759.6  
Thermistor  
Voltage  
(Volts DC)  
3.120  
3.086  
3.047  
3.018  
2.983  
2.949  
2.910  
2.876  
2.842  
2.808  
2.773  
2.739  
2.705  
2.671  
2.637  
2.603  
2.568  
2.534  
2.505  
2.471  
2.437  
2.402  
2.368  
2.334  
2.305  
2.271  
2.236  
2.207  
2.173  
2.144  
2.109  
2.080  
2.046  
2.017  
1.987  
1.958  
1.924  
1.895  
1.865  
1.836  
1.807  
1.777  
1.753  
1.724  
1.694  
1.670  
1.641  
1.616  
1.587  
1.563  
Actual  
Temp.  
(F)  
80.0  
81.0  
82.0  
83.0  
84.0  
85.0  
86.0  
87.0  
88.0  
89.0  
90.0  
91.0  
92.0  
93.0  
Actual  
Resistance  
(Ohms)  
9297.5  
9075.9  
8860.2  
8650.4  
8446.2  
8247.5  
8054.1  
7865.8  
7682.5  
7504.2  
7330.5  
7161.4  
6996.7  
6836.3  
6680.1  
6528.0  
6379.8  
6235.5  
6094.8  
5957.8  
5824.3  
5694.2  
5567.4  
5443.8  
5323.3  
5205.9  
5091.5  
4979.9  
4871.1  
4765.0  
4661.5  
4560.6  
4462.2  
4366.3  
4272.6  
4181.3  
4092.2  
4005.3  
3920.5  
3837.7  
3756.9  
3678.1  
3601.1  
3526.5  
3453.6  
3382.4  
3313.0  
3245.1  
3178.9  
3114.2  
3051.0  
Thermistor  
Voltage  
(Volts DC)  
1.533  
1.509  
1.484  
1.460  
1.436  
1.411  
1.387  
1.362  
1.343  
1.318  
1.294  
1.274  
1.250  
1.230  
1.211  
1.187  
1.167  
1.147  
1.128  
-20.0  
-19.0  
-18.0  
-17.0  
-16.0  
-15.0  
-14.0  
-13.0  
-12.0  
-11.0  
-10.0  
-9.0  
-8.0  
-7.0  
-6.0  
-5.0  
-4.0  
-3.0  
-2.0  
-1.0  
30.0  
31.0  
32.0  
33.0  
34.0  
35.0  
36.0  
37.0  
38.0  
39.0  
40.0  
41.0  
42.0  
43.0  
44.0  
45.0  
46.0  
47.0  
48.0  
49.0  
50.0  
51.0  
52.0  
53.0  
54.0  
55.0  
56.0  
57.0  
58.0  
59.0  
60.0  
61.0  
62.0  
63.0  
64.0  
65.0  
66.0  
67.0  
94.0  
95.0  
96.0  
97.0  
98.0  
99.0  
1.108  
0.0  
1.0  
2.0  
3.0  
4.0  
5.0  
6.0  
7.0  
100.0  
101.0  
102.0  
103.0  
104.0  
105.0  
106.0  
107.0  
108.0  
109.0  
110.0  
111.0  
112.0  
113.0  
114.0  
115.0  
116.0  
117.0  
118.0  
119.0  
120.0  
121.0  
122.0  
123.0  
124.0  
125.0  
126.0  
127.0  
128.0  
129.0  
130.0  
1.089  
1.069  
1.050  
1.030  
1.016  
0.996  
0.977  
0.962  
0.942  
0.928  
0.913  
0.894  
0.879  
0.864  
0.850  
0.835  
0.820  
0.806  
0.791  
0.776  
0.762  
0.747  
0.732  
0.723  
0.708  
0.698  
0.684  
0.674  
0.659  
0.649  
0.635  
8.0  
9.0  
10.0  
11.0  
12.0  
13.0  
14.0  
15.0  
16.0  
17.0  
18.0  
19.0  
20.0  
21.0  
22.0  
23.0  
24.0  
25.0  
26.0  
27.0  
28.0  
29.0  
68.0  
69.0  
70.0  
71.0  
72.0  
73.0  
74.0  
75.0  
76.0  
77.0  
40385.3  
39202.7  
38057.9  
36950.0  
35877.4  
78.0  
79.0  
9525.4  
1. Overall accuracy for any of the sensors is at least + 2 F over the range shown. Accuracy of matched sensors is + 1 F over specific ranges.  
2. As you compare a thermistor resistance (or input voltage) reading with the “actual” temperature indicated by the thermometer, be sure to  
consider the precision and location of the thermometer when you decide whether or not the thermistor is out of specified accuracy.  
3. The thermistor resistances given do not account for the self-heating effects that are present when connected to the UCM. A connected  
“operating” thermistor will read a slightly lower (less than 1%) resistance.  
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Temperature Sensor Checkout  
Table 4  
Sensor Conversion Data: Saturated Condenser and Entering Oil Temperature Matched Pairs  
(6RT12, 3B1RT1; 6RT13, 4B1RT2)  
Actual  
Temp.  
(F)  
0.0  
1.0  
2.0  
3.0  
4.0  
5.0  
6.0  
7.0  
8.0  
9.0  
10.0  
11.0  
12.0  
13.0  
14.0  
15.0  
16.0  
17.0  
18.0  
19.0  
20.0  
21.0  
22.0  
23.0  
24.0  
25.0  
26.0  
27.0  
28.0  
29.0  
30.0  
31.0  
32.0  
33.0  
34.0  
35.0  
36.0  
37.0  
38.0  
39.0  
40.0  
41.0  
42.0  
43.0  
44.0  
45.0  
46.0  
47.0  
48.0  
49.0  
Actual  
Resistance  
(Ohms)  
87510.3  
84745.9  
82072.1  
79500.1  
77012.3  
74609.7  
72288.8  
70047.4  
67881.9  
65790.2  
63768.7  
61815.3  
59927.8  
58103.1  
56339.6  
54634.7  
52986.4  
51392.6  
49851.6  
48360.9  
46919.2  
45524.6  
44175.6  
42870.3  
41607.6  
40385.3  
39202.7  
38057.9  
36950.0  
35877.4  
34838.9  
33833.3  
32861.4  
31935.3  
31038.7  
30170.5  
29329.5  
28515.0  
27725.9  
26961.4  
26220.8  
25503.0  
24807.5  
24133.3  
23479.7  
22846.1  
22231.9  
21636.2  
21058.7  
20498.4  
Thermistor  
Voltage  
(Volts DC)  
4.651  
4.641  
4.630  
4.619  
4.608  
4.596  
4.584  
4.572  
4.560  
4.547  
4.534  
4.521  
4.507  
4.494  
4.479  
4.465  
4.450  
4.435  
4.420  
4.404  
4.388  
4.372  
4.355  
4.338  
4.321  
4.303  
4.285  
4.266  
4.248  
4.229  
4.209  
4.190  
4.170  
4.150  
4.130  
4.109  
4.088  
4.067  
4.045  
4.024  
4.002  
3.979  
3.957  
3.934  
3.910  
3.887  
3.863  
3.839  
3.815  
3.790  
Actual  
Temp.  
(F)  
Actual  
Resistance  
(Ohms)  
19955.0  
19427.9  
18916.5  
18420.3  
17938.8  
17471.6  
17018.0  
16577.8  
16150.5  
15735.7  
15332.9  
14941.7  
14561.9  
14193.0  
13834.6  
13486.5  
13148.3  
12819.8  
12500.5  
12190.2  
11888.7  
11595.6  
11310.7  
11033.7  
10764.4  
10502.6  
10248.0  
10000.0  
9759.6  
9525.4  
9297.5  
Thermistor  
Voltage  
(Volts DC)  
3.765  
3.740  
3.715  
3.689  
3.664  
3.638  
3.611  
Actual  
Temp.  
(F)  
Actual  
Resistance  
(Ohms)  
5824.3  
5694.2  
5567.4  
5443.8  
5323.3  
5205.9  
5091.5  
4979.9  
4871.1  
4765.0  
4661.5  
4560.6  
4462.2  
4366.3  
4272.6  
4181.3  
4092.2  
4005.3  
3920.5  
3837.7  
3756.9  
3678.1  
3601.1  
3526.5  
3453.6  
3382.4  
3313.0  
3245.1  
3178.9  
3114.2  
3051.0  
2989.2  
2928.9  
2870.0  
2812.4  
2756.2  
2701.2  
2647.5  
2595.0  
2543.7  
2493.6  
2444.6  
2396.7  
2349.9  
2304.1  
2259.2  
2216.0  
2172.8  
2131.6  
2090.4  
2051.2  
Thermistor  
Voltage  
(Volts DC)  
2.356  
2.327  
2.300  
2.272  
2.244  
2.217  
2.189  
2.162  
2.135  
2.108  
2.082  
2.055  
2.029  
2.003  
1.977  
1.951  
1.926  
1.901  
50.0  
51.0  
52.0  
53.0  
54.0  
55.0  
56.0  
57.0  
58.0  
59.0  
60.0  
61.0  
62.0  
63.0  
64.0  
65.0  
66.0  
67.0  
68.0  
69.0  
70.0  
71.0  
72.0  
73.0  
74.0  
75.0  
76.0  
77.0  
78.0  
79.0  
80.0  
81.0  
82.0  
83.0  
84.0  
85.0  
86.0  
87.0  
100.0  
101.0  
102.0  
103.0  
104.0  
105.0  
106.0  
107.0  
108.0  
109.0  
110.0  
111.0  
112.0  
113.0  
114.0  
115.0  
116.0  
117.0  
118.0  
119.0  
120.0  
121.0  
122.0  
123.0  
124.0  
125.0  
126.0  
127.0  
128.0  
129.0  
130.0  
131.0  
132.0  
133.0  
134.0  
135.0  
136.0  
137.0  
138.0  
139.0  
140.0  
141.0  
142.0  
143.0  
144.0  
145.0  
146.0  
147.0  
148.0  
149.0  
150.0  
3.585  
3.558  
3.531  
3.504  
3.477  
3.450  
3.422  
3.394  
3.366  
3.338  
3.310  
3.282  
3.253  
3.225  
3.196  
3.167  
3.139  
3.110  
3.081  
3.051  
3.022  
2.993  
2.964  
2.935  
2.905  
2.876  
2.847  
2.817  
2.788  
2.759  
2.730  
2.700  
2.671  
2.642  
2.613  
2.584  
2.555  
2.526  
2.498  
2.469  
2.440  
2.412  
2.384  
1.876  
1.851  
1.826  
1.802  
1.777  
1.754  
1.730  
1.707  
1.684  
1.661  
1.638  
1.615  
1.593  
1.571  
1.549  
1.528  
1.506  
1.485  
1.464  
1.444  
1.423  
1.403  
1.383  
1.364  
1.344  
1.325  
1.306  
1.287  
1.269  
1.250  
1.232  
1.215  
9075.9  
8860.2  
8650.4  
8446.2  
8247.5  
8054.1  
7865.8  
7682.5  
88.0  
89.0  
90.0  
91.0  
92.0  
93.0  
94.0  
95.0  
96.0  
97.0  
7504.2  
7330.5  
7161.4  
6996.7  
6836.3  
6680.1  
6528.0  
6379.8  
6235.5  
6094.8  
5957.8  
98.0  
99.0  
1.197  
1. Overall accuracy for the sensor is at least + 2 F over the range shown.  
2. As you compare a thermistor resistance (or input voltage) reading with the “actual” temperature indicated by the thermometer, be sure to  
consider the location and precision of the thermometer when you decide whether or not the thermistor is out of specified accuracy.  
3. The thermistor resistances given do not account for the self-heating effects that are present when connected to the UCM. A connected  
“operating” thermistor will read a slightly lower (less than 1%) resistance.  
18  
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Compressor Operation  
This feature is called the Auto Lead/Lag and can be found in the Service  
Settings Group, under the “Balanced CPRSR Starts and Hours” menu. When  
this function is disabled, the UCM always starts compressor A” first. When  
this function is enabled, the following occurs:  
The UCM equalizes operating starts and hours. This will cause the  
compressor with the least amount of starts to be started first. When a  
compressor starts, it is always started unloaded.  
When a compressor is stopped, it shuts down in an unloaded state, unless  
taken out by a manual reset diagnostic.  
When the first compressor is brought on line, it attempts to meet the load by  
staging on the step load solenoid and by pulsing the male slide valve load  
solenoid. If one compressor cannot meet the load demand, the second  
compressor is brought on line. It also attempts to meet the load demand by  
staging on its step load solenoid and by pulsing its male slide valve solenoid.  
When both compressors are running and both of their step load solenoids are  
energized, the male load and unload solenoids on both compressors are  
pulsed, thus modulating their respective slide valves to balance the load. The  
UCM attempts to distribute the load evenly between the two compressors.  
When the load drops off, the compressor with the most hours will always be  
the first to unload and turn off. The anti-recycle timer is approximately 5  
minutes from start to start. The minimum time between compressor  
shutdown and restart is approximately 10 seconds, but only if the  
compressor has been running over 5 minutes or longer prior to shutting down  
on temperature. Otherwise, it is the remaining portion of the 5 minutes.  
Restart Inhibit Timer  
If compressor operation is interrupted by an extended (not momentary) loss  
of power or a manual reset, there will be a two minute delay between the  
power up or manual reset and the start of a compressor, assuming there is a  
call for cooling. The timer is factory set at 2 minutes but can be field adjusted  
from 30 seconds to two minutes in the Service Settings Group.  
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Compressor Start/Stop  
To start a compressor after either a “normal' shutdown, a Diagnostic reset, or  
power-on-reset, the following sequence will occur:  
1. On a call for a compressor, the Restart Inhibit Timer will time out, if any  
time remains.  
2. The EXV is positioned to the initial closed start position. At the same  
time, the unload solenoid is energized and the load solenoid is de-ener-  
gized. Timing is determined by the time required to position the EXV  
3. After the EXV is positioned:  
the compressor is turned on  
the compressor heater is de-energized  
the saturated evaporator ref. temp. cutout ignore time is set, based on  
the saturated condenser temperature. Prior to start, the condenser tem-  
perature approximates the ambient temperature.  
the fan control algorithm is executed  
To stop a compressor due to either the Stop button on the CLD or an  
External/Remote “STOP, the sequence shall be as follows:  
1. The unload solenoid is energized for 20 seconds and the load solenoid is  
de-energized. The compressor continues to run for the remaining 20 sec-  
onds. This is defined as the RUN:UNLOAD mode.  
2. The compressor and the fans are turned off. The crankcase heater is  
energized.  
3. The unload solenoid remains energized for 60 minutes after the compres-  
sor stops. The load solenoid is de-energized.  
4. The EXV is closed. Closing begins at maximum speed when the com-  
pressor is turned off. (Max. speed is 25 steps per second, full stroke is  
757 steps.  
5. After 60 minutes, the unload solenoid de-energizes.  
The RUN:UNLOAD mode is also used to stop a compressor due to normal  
LWT control, Low Ambient Run Inhibit, or Freeze Avoidance.  
A compressor stop due to any diagnostic will skip step 1 above and go  
directly to step 2.  
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Variable Speed  
Inverter/Condenser Fan Control  
When Fan Control and Variable Speed Fan (VSF) are set to Enable in the  
Machine Configuration Menu, the UCM will control both the variable speed  
fan and the remaining constant speed fans per the VSF Control Algorithm. If  
VSF Control is disabled for a given circuit but Fan Control is enabled for the  
machine, the circuit will perform normal constant speed fan control. The VSF  
is enabled and operational, the control attempts to provide a 70 5 psid  
between the Condenser Pressure and the Evaporator Pressure (as derived  
from the temperature sensor measurements).  
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Figure 4  
Variable Speed Fan (VSF) and Fan Staging Control  
The VSF Inverter is commanded to a given speed by the UCM, using a PWM  
(Pulse Width Modulated) signal (10V, 15mA, 10 Hz Fundamental) with a duty  
cycle proportional to the desired voltage and frequency from the Inverter. The  
UCM also controls power to the Inverter through a contactor. The Inverter  
Contactor for the respective circuit is energized approximately 20 seconds  
prior to compressor start on that circuit. The VSF Control algorithm runs on a  
5-second interval and is limited to a commanded rate of change of no greater  
than 40% of full speed per interval. The same algorithm that controls the  
RLC-SVD03A-EN  
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Variable Speed Inverter/  
Condenser Fan Control  
speed will also cause constant speed fans to stage On and Off when the  
inverter is commanded to full speed and minimum speed respectively. The  
stage On (or Off) of a constant speed fan will occur if the inverter speed  
command is at max (or min.) for three consecutive intervals (15 seconds).  
Outdoor Air Temperature and Fan Control  
Outdoor air temperature is used to provide a reasonable startup state. Using  
this temperature, the algorithm automatically determines the number of  
constant speed fans to turn on immediately at compressor start. The outdoor  
air temperature sensor is also used to anticipate new states during normal  
running to minimize pressure upsets. This anticipation is based on the staging  
and unstaging of compressor steps at given leaving water temperatures. In  
this way, precise airflow can be maintained, allowing for stable differential  
pressures under part load and low ambient conditions.  
VSF Inverter Fault  
A fault signal will be sent to the UCM from the Inverter when it has gone  
through a self-shutdown or if the output frequency of the Inverter is being  
limited to less than 50% of the signal speed commanded by the UCM. Upon  
receipt of the fault signal, the UCM shall attempt to reset the fault by sending  
a 0 PWM command to the Inverter for a total of five seconds. The fault signal  
will again be checked and repeated if still in fault. If four faults are detected  
within one minute of each other, the power to the Inverter will be cycled off  
for 30 seconds (through contactor control) and then re-powered. If the fault  
still remains or occurs again within one minute, an IFW diagnostic occurs.  
The UCM will remove power from the Inverter and attempt to run the  
remaining constant-speed fans using normal constant-speed Fan Control  
Algorithm. See page 80 for step-by-step troubleshooting procedure.  
22  
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Current Transformer  
Each compressor motor has all three of its line currents monitored by torroid  
(doughnut) current transformers. While the MCSP utilizes all three of the  
signals, it only displays the maximum phase at any given time. These currents  
are normalized with respect to the Rated Load Amps of the respective  
compressor and thus are expressed in terms of % (percent) RLA. The  
currents are “normalized” thru the proper selection of the Current Trans-  
former, the setting of the Compressor Current Overload dip switch (SW2) on  
the MCSPs, and the redundant programming of the decimal equivalent of  
these settings in the Service Settings Group of the CLD. (The term  
“Compressor Current Overload setting” is actually a misnomer. Instead the  
setting should be thought of as an internal software gain that normalizes the  
currents to a % RLA for a given CT and compressor rating. The true nominal  
steady state overload setting is fixed at 132%). Refer to Tables 5 thru 9 for  
setup details.  
The current transformers provide the input for six basic functions of the  
MCSP:  
1. Motor overload protection using a programmed “% RLA versus time to  
trip” characteristic. Refer to Table 6 for details. The steady state “must  
trip” value is 140% RLA and the “must hold” value is 125% RLA. The  
MCSP will trip out the compressor. The appropriate diagnostic descrip-  
tions are then displayed in the CLD diagnostic section.  
2. Verifying contactor drop-out. If currents corresponding to less than 12  
7% RLA are not detected on all three of the monitored compressor  
phases within approximately 5 seconds after an attempted contactor  
drop-out, the compressor will continue to be commanded Off, the Unload  
solenoid will be pulsed, the EXV will be opened to its fullest position, and  
the fans will continue to be controlled. This condition will exist until the  
diagnostic is manually reset.  
3. Loss of Phase Current. If the detection of any or all of the three motor  
phase currents falls below 12 7% RLA for 2 1 seconds while the  
branch circuit should be energized, the MCSP will trip out the compres-  
sor. The Phase Loss diagnostic, or the Power Loss diagnostic, will be dis-  
played. Failure of a contactor to pull in will cause the Phase Loss  
diagnostic. However when reduced voltage starting is employed, it may  
take an additional 3 seconds to detect a phase loss at startup, as phase  
loss protection is not active during the 3 second transition time.  
4. Phase Rotation. Screw compressors cannot be allowed to run in reverse  
direction. To protect the compressors, the phase rotation is detected by  
the current transformers immediately at start up. If improper phasing is  
detected, within 1 second of startup, the MCSP will trip out the compres-  
sor. The Phase Rotation diagnostics will be displayed. This function is not  
sensitive to the current transformer's polarity.  
5. Phase Unbalance. The MCSP will shut down the compressor if a phase  
current unbalance is detected by the current transformers while the com-  
pressor is running. A 15% unbalance, if protection is enabled, will cause  
the MCSP to trip out the compressor. The Phase Unbalance diagnostics  
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Current Transformer  
will be displayed. If this protection is disabled, a 30% phase unbalance  
will still be in effect with the diagnostic code Severe Phase Imbalance  
being displayed.  
6. Current Limit. The MCSP will begin to unload its compressor as the  
%RLA exceeds 120%. Further, the CPM will cause the compressors to  
automatically unload when the Chiller Current Limit Setpoint is reached.  
The Current Limit Setpoint is set in the Service Setting Group. Individual  
compressor phase currents are averaged and added together to compare  
to the Chiller Current Limit which is in terms of % Total of all of the  
Compressor RLNs.  
NOTE: The current transformers are NOT polarity or directionally sensitive.  
CT and MCSP Compressor Current Input Checkout  
Procedure  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
1. Check incoming 3-phase power for voltage within 10% of nominal per  
Chiller nameplate.  
2. Interrogate the CPM for all of the presently active diagnostic codes or the  
historic diagnostic codes in the Diagnostics Menu. Narrow the problem  
down to a particular compressor or contactor as noted above. Write down  
all of the diagnostic codes stored in the diagnostic registers.  
If there is any question as to which compressor or current transformer is  
causing a problem, or simply to verify and “witness” the problem, an  
attempt should be made to restart the chiller after clearing diagnostics.  
The diagnostics can be cleared by entering the Diagnostics Menu and  
stepping to the CLEAR DIAGNOSTICS display.  
It is possible to “force” certain compressors to be the first or next com-  
pressor to stage on, using the “Compressor Test” feature in the Service  
Tests Menu. The Leaving Water Temperature must, however, be above  
the Chilled Water Setpoint by more than the “differential to start” setting,  
in order to stage on the first compressor.  
At startup, verify the appropriate contactor(s) pull-in. The “Compressors  
On” menu item in the Chiller Report Group will indicate which compres-  
sor started approximately five seconds after the contactor pulls in. Note  
the diagnostic(s) that results, then place the Chiller into the “Stop” mode  
by depressing the Stop button on the CLD.  
24  
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Current Transformer  
ƽ WARNING  
Hazardous Voltage w/Capacitors!  
Disconnect all electric power, including remote disconnects  
before servicing. Follow proper lockout/tagout procedures to  
ensure the power cannot be inadvertently energized. For variable  
frequency drives or other energy storing components provided by  
Trane or others, refer to the appropriate manufacturer’s literature  
for allowable waiting periods for discharge of capacitors. Verify  
with an appropriate voltmeter that all capacitors have discharged.  
Failure to disconnect power and discharge capacitors before  
servicing could result in death or serious injury.  
Note: For additional information regarding the safe discharge of  
capacitors, see PROD-SVB06A-EN or PROD-SVB06A-FR  
3. For the next portion of the procedure, pull the unit's disconnect and inter-  
rupt all high voltage power to the control panel. Locate the torroid (dough-  
nut) current transformers encircling the compressor power wiring and  
branching to the compressor contactors of the suspect compressor-in the  
control panel. Refer to the Component Location Drawing in the panel to  
identify the particular current transformer(s) of interest. Locate the part  
number/UL tag on the transformer leads and note the Trane part number  
which identifies the transformers. Note: all compressors of a given ton-  
nage should have the same transformer extension number. Verify the  
proper current transformer using Table 5 in this section. Also check the  
setting of the dip switch (SW2) on each of the MCSP modules and verify  
these against Table 5 for each compressor. (Switch position SW2-1 is the  
Most Significant Bit). The decimal equivalent of this setting should also  
be verified in the Service Setting Group under the “CURRENT OVRLD  
SETTINGS” display. If the programmed value does not agree with the dip  
switch setting for each of the MCSP's, an informational diagnostic will  
result. The compressors will be allowed to run, but default settings (the  
most sensitive possible) will be used for the internal software compres-  
sor current gains.  
4. Utilizing the Schematic Wiring Diagram, locate the termination of the  
transformer's wiring into the MTA plug at the appropriate MCSP module  
at pin header J5. Pull off the appropriate MTA connector from the pin  
header on the MCSP.  
Current Transformers can be damaged and high voltages can result due  
to running the compressors without a suitable burden load for the CTs.  
This load is provided by the MCSP input. Take care to properly reconnect  
the CT's MTA prior to attempted start of the compressors.  
5. Using a digital volt-ohmmeter, measure the resistance of the trans-  
former(s) by probing the appropriate pair(s) of receptacles within the  
MTA. The receptacle pairs of the MTA are most easily measured by using  
meter leads with pointed probes and contacting the exposed metal of the  
connector through either the top or the side of the MTA. (It may be nec-  
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Current Transformer  
essary to remove a cap over the top of the connector to gain access to  
the connector conductors.)  
6. Refer to Table 7 which lists the normal resistance range for each exten-  
sion of current transformer. Check the measured resistance against the  
value listed per transformer extension. If the resistance is within toler-  
ance, the transformer and MTA can be considered good. Go on to step 8.  
7. If the resistance reading above is out of tolerance, the problem is either  
with the transformer, its wiring, or the MTA connector. First double check  
the schematic to be sure you are working the proper lead pair. Then cut  
the leads to the particular transformer near the MTA connector and  
repeat the resistance measurement by stripping insulation from the  
wire's end. Once the fault has been isolated in this manner, reconnect  
leads or install a new transformer or connector.  
More than one current transformer is terminated to a single MTA. When  
replacing, take care to note the proper positions of the respective trans-  
former wire terminations on the MTA for the re-termination. The current  
transformers are NOT polarity or directionally sensitive. The transformer  
lead wiring is #22 AWG, UL 1015 600V and the proper MTA connector  
(red color code) must be used to ensure a reliable connection. If the fault  
can be isolated to the current transformer or its wiring apart from the con-  
nector, the connector can be reused by cutting off the bad transformer  
and splicing in a new transformer using wire nuts.  
8. If the transformer/connector resistance proves accurate, recheck the  
resistance with the connector held at different angles and with a light  
lead pull (less than 5 lb.) to test for an intermittent condition.  
9. To perform the following test, you will need to use a digital voltmeter with  
a diode test function,. With the transformer MTA disconnected and the  
power off to the MCSP, perform a diode test across the corresponding  
pair of current transformer input pins on the MCSP (header J5). The  
meter should read from 1.0 to 1.5 volts for each current transformer input.  
Repeat using the opposite polarity. The same reading should result.  
Extreme errors suggest a defective MCSP module. If the diode voltage  
drops prove accurate, reconnect the transformers to the MCSP and  
repower the unit.  
10. With the CT's reconnected to the MCSP, attempt a restart of the chiller.  
As the given compressor is started, and the inrush locked rotor transient  
has passed, (locked rotor transient should last less than one second)  
simultaneously monitor the actual compressor phase current(s) (using a  
clamp-on type ammeter) and the voltage developed at the respective cur-  
rent transformer's termination at the MCSP (using a digital volt-meter on  
a 0-20 VAC scale). Refer to Table 8 for the compressor phase current to  
output voltage relationship for each extension current transformer. Using  
Table 8, look up to current that corresponds to the output voltage read by  
the voltmeter and compare to ammeter reading. Assuming relatively  
accurate meters, the values should agree to within 5%.  
11. If the measured current and the output voltage from the CT agree within  
the tolerance specified, the CT is good. If diagnostics, overload trips, or  
other problems potentially involving current sensing continue to occur  
26  
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Current Transformer  
with all phase currents to the compressors verified to be within their nor-  
mal range, then the problem is either with the CT selection, MCSP Com-  
pressor Overload Dip Switch Setting, or the MCSP's current input, analog  
to digital (A/D), or dip switch input circuitry. Since the first two items  
were verified in Step 2 using Table 5, that leaves only the MCSP circuitry  
as an issue. It is advisable to replace the MCSP module at this point.  
However if verification of the MCSP Current sensing operation is desired,  
go to step 12 below.  
12. There are two ways that the MCSP's current sensing can be checked.  
Both methods use the CLD display of the %RLA from each MCSP (Com-  
pressor Report) for indication of the sensed current. The first is straight-  
forward equation and assumes that the proper Compressor Overload dip  
switch setting and current transformer have been selected:  
Measured Compr. amps of max. phase  
-------------------------------------------------------------------------------------------------------  
%RLA =  
Nameplate Compressor RLA  
To check the displayed % RLA as a function of the output voltage from the  
current transformers (as connected at the MCSP), Tables 8 and 9 are utilized.  
In Table 8 look up (or interpolate) the “% of CT rating” corresponding to the  
maximum of the three CT Input Voltages (VAC rms) as read at the MCSP. (The  
table is necessary because the voltage developed at the MCSP is not linear  
with the CT's secondary current). Next, check the Compressor Current  
Overload setting of switch SW2 on the MCSP and find the corresponding  
“SOFTWARE GAIN” in Table 9. The % RLA displayed by the CPM should be:  
%RLA = % CT Rating X SOFTWARE GAIN  
The preceding equations should only be applied during steady state current  
draws (after transition). Inrush transient currents and associated CT output  
voltages can be expected to be from 3 to 6 times the steady state values, and  
the displayed value only reads up to 255% RLA. The accuracy of the  
displayed value should be within 5% of that predicted using the Input  
voltage. However, the end to end accuracy of the displayed value compared  
to the actual %RLA max. phase current is 3.3% over the range of 50 to  
150% of CT rating.  
13. If no phase currents are measured with the amprobe on any or all of the  
legs to a given compressor immediately following the attempted staging  
of that compressor by the MCSP, the problem lies either with the  
contactor, motor circuit or the MCSP relay outputs. Refer to MCSP  
RLC-SVD03A-EN  
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Current Transformer  
Table 5  
Compressor Overload DIP Switch Settings  
Current  
Transformer  
Overload Setting  
Dip Sw/Decimal  
Primary Turns  
Through Current  
Transformer  
Compressor  
Tons  
*
**  
Volts/Hz  
RLA  
Extension  
12345  
35  
40  
50  
60  
200/60  
230/60  
346/50  
380/60  
400/50  
460/60  
575/60  
200/60  
230/60  
346/50  
380/60  
400/50  
460/60  
575/60  
200/60  
230/60  
346/50  
380/60  
400/50  
460/60  
575/60  
200/60  
230/60  
346/50  
380/60  
400/50  
460/60  
575/60  
115  
100  
58  
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
-02  
-01  
-10  
-10  
-10  
-10  
-01  
-02  
-02  
-01  
-01  
-10  
-10  
-01  
-03  
-03  
-01  
-02  
-01  
-01  
-02  
-04  
-04  
-02  
-02  
-02  
-02  
-03  
01011/11  
11111/31  
01100/12  
10000/16  
00000/0  
00000/0  
01111/15  
11011/27  
10001/17  
00111/7  
61  
50  
50  
40  
142  
124  
72  
75  
01010/10  
10001/17  
10001/17  
11111/31  
11100/28  
10010/18  
11100/28  
00001/1  
10011/19  
10011/19  
10111/23  
10011/19  
01000/8  
01101/13  
10001/17  
00001/1  
00001/1  
10000/16  
62  
62  
50  
192  
167  
96  
101  
84  
84  
67  
233  
203  
117  
123  
101  
101  
81  
*The current transformer base part number is X13580253. The numbers in this column are suffixes of the base part number.  
**On the DIP switch, 1=ON, O=OFF. The decimal value should be set in the compressor overload setting menu of the UCM. If the  
DIP switch value does not match the decimal value entered into the UCM, the related compressor(s) will continue to run, but a  
diagnostic will be initiated, both settings will be ignored, and the UCM will use the lowest possible trip setting value.  
28  
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Current Transformer  
Table 6  
Trip Times Vs. % Current  
MOTOR CURRENT  
(% RATED RLA)  
TRIP TIME (SEC)  
NOMINAL  
MINIMUM  
MAXIMUM  
127.7 or below  
132.0  
No trip  
27.2  
27.2  
22.8  
18.8  
16.0  
14.0  
12.4  
11.2  
10.4  
9.6  
No Trip  
No Trip  
30.08  
25.28  
20.48  
17.28  
15.28  
13.28  
12.08  
10.88  
10.08  
9.28  
No Trip  
No Trip  
No Trip  
28.09  
22.89  
19.29  
16.89  
14.89  
13.29  
12.09  
10.89  
10.09  
9.69  
132.1  
140.0 (must trip pt.)  
150.0  
160.0  
170.0  
180.0  
190.0  
200.0  
210.0  
220.0  
8.8  
230.0  
8.0  
8.48  
240.0  
7.6  
8.08  
8.89  
250.0  
7.2  
7.68  
8.49  
260.0  
6.8  
6.88  
7.69  
270.0  
6.4  
6.88  
7.29  
280.0  
6.0  
6.48  
6.89  
290.0  
5.6  
6.08  
6.89  
300.0  
4.0  
5.68  
6.49  
300.1  
4.0  
4.08  
6.49  
310.2 or above  
4.0  
4.08  
4.49  
Table 7  
Current Transformers Ratings and Resistance  
RATING  
USABLE  
RESISTANCE  
OHMS + 10%  
*
EXT  
RANGE  
01  
02  
03  
04  
05  
09  
10  
100A  
150A  
200A  
275A  
400A  
50A  
23.5  
35.0  
46.0  
67.0  
68.0  
11.5  
17.0  
66.67 -100A  
100 - 150A  
134 - 200A  
184 -275A  
267 - 400A  
33.37 - 50A  
50 - 75A  
75A  
*The current transformer base part number is X13580253. The  
numbers in this column are suffixes of the base part number.  
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Current Transformer  
Table 8  
Compressor Phase Current vs. AC Input Voltage at MCSP  
ACTUAL COMPRESSOR PHASE AMPS THRU CT  
TERMINAL  
VOLTAGE  
(V RMS)  
EXT  
-01  
EXT  
-02  
EXT  
-03  
EXT  
-04  
EXT  
-05  
EXT  
-09  
EXT  
-10  
% OF CT  
RATING  
0
5
10  
15  
20  
25  
30  
35  
40  
45  
50  
55  
60  
65  
70  
75  
0
8
15  
23  
30  
38  
45  
53  
60  
68  
75  
83  
90  
98  
105  
113  
120  
128  
135  
143  
150  
158  
165  
173  
180  
188  
195  
203  
210  
218  
225  
240  
255  
270  
285  
300  
315  
330  
345  
360  
375  
390  
405  
420  
435  
450  
0
10  
20  
30  
40  
50  
60  
70  
0
14  
28  
41  
55  
69  
83  
96  
0
20  
40  
60  
0
2.5  
5
7.5  
10  
12.5  
15  
17.5  
20  
22.5  
25  
27.5  
30  
32.5  
35  
37.5  
40  
42.5  
45  
47.5  
50  
52.5  
55  
57.5  
60  
62.5  
65  
67.5  
70  
0
3.75  
7.5  
11.25  
15  
18.75  
22.5  
26.25  
30  
33.75  
37.5  
41.25  
45  
48.75  
52.5  
56.25  
60  
63.75  
67.5  
71.25  
75  
78.75  
82.5  
86.25  
90  
93.75  
97.75  
101.25  
105  
108.75  
112.5  
120  
127.5  
135  
142.5  
150  
157.5  
165  
172.5  
180  
0.00  
1.19  
1.37  
1.53  
1.67  
1.81  
1.95  
2.09  
2.23  
2.36  
2.50  
2.63  
2.77  
2.90  
3.03  
3.17  
3.30  
3.43  
3.57  
3.70  
3.83  
3.96  
4.10  
4.23  
4.36  
4.49  
4.62  
4.75  
4.88  
5.02  
5.15  
5.41  
5.67  
5.94  
6.20  
6.46  
6.72  
6.99  
7.25  
0
5
10  
15  
20  
25  
30  
35  
40  
45  
50  
55  
60  
65  
70  
75  
80  
100  
120  
140  
160  
180  
200  
220  
240  
260  
280  
300  
320  
340  
360  
380  
400  
420  
440  
460  
480  
500  
520  
540  
560  
580  
600  
640  
680  
720  
760  
800  
840  
880  
920  
960  
1000  
1040  
1080  
1120  
1160  
1200  
80  
90  
110  
124  
138  
151  
165  
179  
193  
206  
220  
234  
248  
261  
275  
289  
303  
316  
330  
344  
358  
371  
385  
399  
413  
440  
468  
495  
523  
550  
578  
605  
632  
660  
687  
715  
742  
770  
797  
825  
100  
110  
120  
130  
140  
150  
160  
170  
180  
190  
200  
210  
220  
230  
240  
250  
260  
270  
280  
290  
300  
320  
340  
360  
380  
400  
420  
440  
460  
480  
500  
520  
540  
560  
580  
600  
80  
85  
90  
95  
80  
85  
90  
95  
100  
105  
110  
115  
120  
125  
130  
135  
140  
145  
150  
160  
170  
180  
190  
200  
210  
220  
230  
240  
250  
260  
270  
280  
290  
300  
100  
105  
110  
115  
120  
125  
130  
135  
140  
145  
150  
160  
170  
180  
190  
200  
210  
220  
230  
240  
250  
260  
270  
280  
290  
300  
72.5  
75  
80  
85  
90  
95  
100  
105  
110  
115  
120  
125  
130  
135  
140  
145  
150  
7.51  
7.77  
187.5  
195  
202.5  
210  
217.5  
225  
8.03  
8.29  
8.56  
8.82  
9.08  
30  
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Current Transformer  
Table 9  
Overload Dip Switch Setting vs. Internal Software Gain  
CPRSR RATED RLA  
AS A % OF CT RATING SWITCH SETTING  
OVERLOAD DP  
DECIMAL  
SETTING  
SOFTWARE  
GAIN  
66  
67  
68  
69  
70  
71  
72  
73  
74  
00000  
00001  
00010  
00011  
00100  
00110  
00111  
01000  
01001  
01010  
01011  
01100  
01101  
01111  
01111  
10000  
10001  
10010  
10011  
10100  
10101  
10110  
10110  
10111  
11000  
11001  
11001  
11010  
11011  
11100  
11100  
11101  
11110  
11110  
11111  
00  
01  
02  
03  
04  
06  
07  
08  
09  
10  
11  
12  
13  
15  
15  
16  
17  
18  
19  
20  
21  
22  
22  
23  
24  
25  
25  
26  
27  
28  
28  
29  
30  
30  
31  
1.500000  
1.483870  
1.467743  
1.451613  
1.435483  
1.403226  
1.387097  
1.370969  
1.354839  
1.338709  
1.322580  
1.306452  
1.290323  
1.258065  
1.258065  
1.241936  
1.225806  
1.209678  
1.193549  
1.177419  
1.161291  
1.145162  
1.145162  
1.129032  
1.112903  
1.096775  
1.096775  
1.080645  
1.064516  
1.048387  
1.048387  
1.032258  
1.016128  
1.016128  
1.000000  
75  
76  
77  
78  
79  
80  
81  
82  
83  
84  
85  
86  
87  
88  
89  
90  
91  
92  
93  
94  
95  
96  
97  
98  
99  
100  
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Under-Over Voltage Transformer  
The hardware required for the Under/Over voltage sensing function of the  
UCM is standard on the 70-125 Ton RTAA chiller. This feature must be  
Enabled in the Service Settings Menu for it to be active. A custom designed  
transformer whose primary is connected across the Line Voltage phases A to  
B, provides a stepped down and isolated AC voltage to the CPM at input J4.  
This secondary voltage is directly proportional to the line voltage applied to  
the primary. The Chiller Report on the CLD can directly display the % Line  
Voltage and, when so enabled, can cause automatically reset MAR  
diagnostics for High and Low Line condition. The % Line Voltage is internally  
calculated by dividing the selected nominal voltage rating (only certain  
discrete values are selectable in the Service Settings Group) by the actual line  
voltage as read and processed by the CPM. With the Under-Over Voltage  
Protection Function enabled, an Over Voltage diagnostic will occur if the  
calculated % Line Voltage equals or exceeds 114%, or an Under Voltage  
diagnostic will occur if it equals or falls below 87% for 15 continuous  
seconds. Reset differential is set at 3%.  
Under-Over Voltage Transformer Checkout  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
1. Locate the Under-Over Voltage Transformer [1T2] in the panel by referring  
to the Component Location Drawing. Carefully measure the primary volt-  
age across the Transformer (Line Voltage Phase A to B) and note the  
value in Vac rms.  
2. Next disconnect the transformers secondary from J4 on the CPM. Using  
voltmeter probes, measure and note the unloaded secondary voltage  
(Vac rms). (low voltage class 2 less than 32 Vac).  
3. The ratio of the primary or line voltage to the open circuity secondary  
voltage should be 20 to 1. If the unloaded turns ratio is not within 2% of  
this value, replace the transformer.  
4. Reconnect the secondary back to J4 and remeasure the loaded (con-  
nected) secondary voltage. The new loaded ratio should be approximately  
20.2 to 1. If not within 2% of this ratio the transformer's secondary  
should be disconnected from the CPM and a 1 Kohm resistor connected  
across the secondary. Measuring the voltage across the 1 Kohm resistor  
should give us a voltage ratio of 20.17. Ratios more than 2% in error sug-  
gest a bad transformer. If the 1 Kohm loaded ratio is within tolerance, but  
the CPM connected ratio is out of tolerance suspect a bad CPM. Before  
32  
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Under-Over Voltage Transformer  
replacing the CPM, double check the Under-Over Voltage Function's  
Nominal Line Voltage Setup in the Service Settings Group.  
5. If the Under-Over Voltage Protection function continues to misoperate,  
and all of the above measured ratios are within tolerance, and all CLD  
Under Over Voltage setups have been verified, replace the CPM. It is a  
good idea, before replacing the CPM, however, to copy down all of setup  
data. This data will be very helpful in making the necessary setup on the  
replacement CPM.  
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Compressor Capacity  
The 35 to 60 ton helical rotary screw compressors are loaded and unloaded  
by means of an internal slide valve and a female unloader valve. In simple  
terms, these valves can regulate the amount of “bite” of the compressor  
rotors as they turn at relatively constant speeds.  
The slide valve is moved by a hydraulic cylinder and piston internal to the  
compressor (the hydraulic fluid is oil from the refrigerant system). The  
movement of the cylinder is controlled by the load and unload solenoid  
valves, which either add oil at compressor discharge pressures, or withdraw  
oil to suction pressures.  
The female unloader valve is moved to either the On or Off position by using  
internal suction and discharge gas pressure. The movement of this valve is  
controlled by the female unloader valve solenoid. These solenoid valves are  
electrically controlled by the MCSP module to handle compressor startup and  
shutdown, maintain chilled water temperature setpoints and limit current,  
condenser pressures, and evaporator temperatures etc.  
Although the solenoids are an on - off” device, effective modulation and high  
resolution of the slide valve (under steady state conditions) is possible by  
pulsing on and off the solenoid valves and varying the displaced volume of  
the cylinder/piston. When a given compressor is operating, the MCSP will  
energize (apply 115 VAC) either the load or the unload solenoid, if necessary,  
for a period of between 40 and 400 milliseconds, once every 10 seconds to  
control water temperature or limit conditions.  
The female unloader valve solenoid receives a constant signal from the UCM  
as the first step in compressor loading and the last step in compressor  
unloading. Just prior to and just after a compressor start, and just before a  
compressor stop, the MCSP will continuously energize the unload solenoid  
for 20 to 30 seconds to assure unloaded starts. After a compressor stop, the  
unload solenoid valve will remain energized for approximately one hour to  
prevent slide valve movement due to changing cylinder/compressor  
pressures.  
The first procedure below will allow the checkout of the MCSP load and  
unload outputs. The next procedure will allow the checkout of the Load and  
Unload Solenoid valves located on the compressor as well as the operation of  
the Slide Valve modulating unloader. Lastly, the female unloader valve and  
solenoid will be discussed.  
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Compressor Capacity  
Checkout Procedure for MCSP Load/Unload Outputs  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
The MCSP controls the Load and Unload Solenoid valves on the respective  
compressor with 115 V triacs (solid state relays). Unlike mechanical relays  
however, a triac has a rather high leakage current when off, comparatively  
speaking. While this leakage is not nearly enough to actuate a solenoid valve,  
it may, under no load conditions (as would be experienced when a solenoid  
coil failed open), look like it was stuck on” when using a voltmeter to test it.  
Thus it is important to verify that the solenoid coil is continuous and providing  
a normal load or to connect a known good load, such as a low wattage 115  
Volt lamp, to the terminals when testing the outputs. Refer to the Chiller  
Control Wiring diagrams and Component Location Drawings for the following  
procedure.  
With the particular compressor running, the triacs may be checked (under  
load as explained above) by measuring the voltage from terminals E7 or E8 to  
115 neutral. The triacs operate in the high side and switch 115 Vac power from  
J7-1 to either E7 (load solenoid) or E8 (unload solenoid) to move the slide  
valve in the appropriate direction. Except during compressor starts and stops,  
in normal operation, the solenoid valves can only be energized for a period of  
between 40 and 400 milliseconds once every 10 seconds. Often, if the chilled  
water setpoint is being met under steady state conditions, they may not  
energize at all. To assure loading and unloading is occurring it may be  
necessary to make slight adjustments to the chilled water setpoints to force  
action. As the pulsed on-time is potentially short it may be difficult to see,  
especially if using a meter movement type voltmeter. (Use of a low wattage  
115 Vac test lamp may be of some help for a visual indication of output triac  
operation.)  
When a triac is off, about 0 Vac should be measured on its terminal with the  
solenoid load connected. When it is on, the voltage should be close to 115  
Vac (the drop across the triac is about 1-2 volts).  
The best time to check the unload solenoid is immediately after a power-up  
reset of the MCSP. For the first 30 seconds after applying power the unload  
solenoid should be on continuously. The next best time to check it is after the  
compressor starts. For the first 30 seconds after a start the unload solenoid  
should be on continuously.  
Checking the load solenoid is more difficult. 30 seconds after a start, the  
compressor will usually start loading, until water temperatures are satisfied.  
Remember however, that under certain limit conditions, the MCSP may  
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Compressor Capacity  
prevent a compressor from loading even if the chilled water setpoint is not  
satisfied. Refer to the RTAA-IOM-4 for discussion on condenser, evaporator,  
and current limiting functions and setpoints. Refer to the Mode display under  
the Chiller Report on the CLD for an indication of the current running mode.  
Checkout Procedure for the Slide Valve and Load/  
Unload Solenoids  
Make sure unit is off and there is no power in the control panel before  
beginning this procedure.  
Setup  
1. Identify the MCSP Module associated with the compressor to be tested  
(1U4 or 1U5). Disconnect the stake-on terminals for the Load and Unload  
Solenoid Valves at the MCSP UCM (E7 and E8 respectively) but take care  
to identify the wires so as to prevent crosswiring when reconnecting.  
ƽ WARNING  
Hazardous Voltage w/Capacitors!  
Disconnect all electric power, including remote disconnects  
before servicing. Follow proper lockout/tagout procedures to  
ensure the power cannot be inadvertently energized. For variable  
frequency drives or other energy storing components provided by  
Trane or others, refer to the appropriate manufacturer’s literature  
for allowable waiting periods for discharge of capacitors. Verify  
with an appropriate voltmeter that all capacitors have discharged.  
Failure to disconnect power and discharge capacitors before  
servicing could result in death or serious injury.  
Note: For additional information regarding the safe discharge of  
capacitors, see PROD-SVB06A-EN or PROD-SVB06A-FR  
2. Install a toggle switch between Control Power HOT (1TB3-8 or 9) and the  
Load and Unload Solenoid Valve leads (previously connected to E7 and  
E8). Initially make sure that the Load toggle switch is open and the  
Unload toggle switch is closed.  
3. Install a pressure gauge with a refrigerant hose (hose should be long  
enough to read the gauge from the control panel) to the slide valve pis-  
ton/cylinder cavity Schrader valve located near the load/unload solenoids.  
4. Reapply power to the unit and place the chiller in the “Stop” mode. Using  
the CLD, select and enable the “Compressor Test” (in the Service Tests  
Menu) for the compressor that is to be run. Additionally, to prevent the  
opposite refrigeration circuit from running, if desired, the circuit can be  
locked out through the CIRCUIT LOCKOUT display in the Service Tests  
Menu for the appropriate circuit. Next place the Chiller into the Auto“  
mode and provide all necessary interlocks and a load (or adjust chilled  
water setpoint) to start the chiller. The selected compressor will be the  
first to stage on (after the restart inhibit timer has expired).  
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Compressor Capacity  
NOTE: Enabling the “Compressor Test” only affects which compressor will  
be cycled on next and is not an override mode. The chiller will continue to  
operate normally (not withstanding circuit lockout) and will stage  
compressors on and off, as well as attempt to modulate running compressors  
to maintain chilled water setpoint. Be aware that during manual control of the  
load/unload solenoids, as explained in item 6, below, other compressors may  
stage and/or attempt to modulate and thus will affect the leaving chilled water  
temperature. However, all diagnostics are still active. No specific action, other  
than reconnecting the solenoid valves to their respective outputs on the  
MCSP, is required to return the Chiller to normal operation.  
5. Allow the compressor to start and monitor compressor currents either in  
the Compressor Report display (maximum phase % RLA) or with a  
clamp-on type ammeter.  
Load  
1. Once the compressor has started, allow the Unload Solenoid Valve to  
remain energized for approximately 30 seconds, then open the Unload  
toggle switch to de-energize the valve. Verify that at least one condenser  
fan is on before continuing with the checkout, as low differential refriger-  
ant pressures will preclude proper Slide Valve operation. Record the cylin-  
der cavity pressure and the compressor currents.  
2. Manually close and open the Load toggle switch, to energize the Load  
Solenoid, in 4 or 5 short “pulses. Each load pulse should be approxi-  
mately one second in duration, with approximately 10 seconds between  
pulses.  
NOTE: Loading the compressor faster than this rate could cause control  
instability and possible diagnostics. Leave the toggle switch open, i.e., valve  
de-energized.  
3. If the %RLA or the current and pressure increases,' then the Load Sole-  
noid and Slide Valve are operating properly.  
4. If the %RLA or current does not increase, read the pressure at the cylin-  
der cavity; Pressure increases, to approximately condenser pressure  
(condenser pressure read via the CLD) without an increase in % RLA  
(unless already fully loaded), indicate the Slide Valve is bound.  
5. If cylinder cavity pressure does not increase, check the coil of the Load  
Solenoid.  
6. If the coil checks out, then one of two problems exist. Either the Load  
Solenoid Valve is malfunctioning or the Unload Valve is stuck open.  
NOTE: Refer to the flow chart shown in Figure 5.  
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Compressor Capacity  
1. Install toggle switches across load and unload solenoid  
2. Install Pressure Gage on slide valve piston/cylinder cavity Schrader valve.  
3. Start Unit.  
Load:  
4. Manually load compressor in short increments.  
Yes  
Good  
5. Does RLA increase?  
Check UCM  
Bad  
Repeat  
procedure  
for unload  
No  
Replace  
Yes  
6. Does Cavity Press  
increase to a level close  
to discharge pressure?  
Slide valve mechanism bound  
No  
Yes  
Yes  
7. Does Magnetic Field on  
Solenoid valve mechanism bound  
or unloader valve stuck open  
Solenoid Coil exist?  
No  
Check for open solenoid coil  
8. Is wiring to valve OK?  
No  
9. Repair and reverify.  
Figure 5  
Unload  
Manual Slide Valve Diagnostic Flow Chart - Load  
NOTE: The following assumes that the compressor's slide valve is already  
at some loaded position and %RLA is higher than the minimum noted in step  
1.  
1. Manually close the Unload toggle switch to continuously energize the  
Unload Solenoid Valve.  
2. If the %RLA decreases, then the Unload Valve and Slide Valve are operat-  
ing properly.  
3. If the %RLA does not decrease, observe the cylinder cavity pressure  
reading.  
4. If cylinder cavity pressure reading decreases to approximately the suction  
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Compressor Capacity  
pressure, then the Slide Valve is bound.  
5. If cylinder cavity pressure does not decrease or is at suction pressure  
before the Unload toggle switch was closed, the problem lies with either  
the solenoid coil or valve.  
6. Check coil  
7. If coil checks out, change the valve.  
NOTE: Refer to the Flow Chart in Figure 6.  
Unload:  
10. Manually unload compressor in short increments.  
Yes  
Good  
Check UCM  
Bad  
Stop  
11. Does RLA Decrease?  
No  
Replace  
Yes  
Slide valve mechanism bound  
12. Does Cavity Press  
decrease to a level  
close to suct pressure?  
No  
Yes  
Yes  
Solenoid valve mechanism bound  
Check for open solenoid coil  
13. Does Magnetic Field on  
Solenoid Coil exist?  
No  
14. Is wiring to valve OK?  
No  
15. Repair and reverify.  
Figure 6  
Manual Slide Valve Diagnostic Flow Chart  
Checkout Procedure for MCSP Step Load Output  
The MCSP controls the step load solenoid valve on the respective  
compressor with a 115 VAC dry contact output relay. This differs from the  
Load/Unload solenoid output, which is from a triac (solid state relay). Refer to  
the Chiller Control Wiring diagrams and the Component Layout Drawings for  
the following procedure.  
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Compressor Capacity  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
With a particular compressor running, the relay may be checked (under load,  
as explained above) by measuring the voltage from terminal J7-9 to the 115  
VAC neutral. The relay operates in the high side and switches power from  
J7-8 to J7-9, to move the step load valve to the loaded position. When the  
CPM decides to load the compressor, the step load solenoid is energized  
continuously. To assure that loading and unloading is occurring, it may be  
necessary to make slight adjustments to the chilled water setpoints to force  
action.  
Checkout Procedure for Step Load Solenoid Valve  
and Piston  
Prior to a compressor start, connect a pressure gauge to the Schrader port  
near the step load solenoid valve. This port is connected to the back side of  
the step load piston and, therefore, will allow direct measurement of the  
pressure that actuates the step load valve. Observe the pressure gauge  
during a compressor start, either from a manual compressor test or a normal  
call for cooling. Initially, the pressure should drop to the suction pressure and,  
when the MCSP calls for compressor loading, the solenoid will actuate and  
supply discharge pressure to the piston. If, after verifying that 115 VAC has  
been applied to the step load solenoid, the pressure does not increase to  
discharge pressure, the step load solenoid coil and/or valve must be replaced.  
Also, when the solenoid valve is energized and the piston pressure is near  
discharge pressure, the percent RLA of the compressor, as seen in the  
Compressor Report, should increase. If the percent RLA does not increase,  
the step load valve is stuck and should be repaired.  
40  
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Module Power and Miscellaneous I/O  
This section will detail the normal voltage levels present on each of the  
modules inputs and outputs under various conditions or states. Typical  
operation of the I/O will be discussed in terms of chiller operation. This should  
help the serviceman determine when and how they should function. Certain  
inputs have been presented in greater detail in earlier sections and these are  
referenced where applicable.  
Power Supply  
All of the modules are powered from 115 VAC 50/60hz Control Power except  
the CLD and the IPCB, which are powered by 24 VAC. This power is provided  
by either a control power transformer or is customer supplied. With the  
exception of the CLD, LCI-C and the IPCB modules, the other modules have  
incoming power connected to the upper-most terminal on the right hand side  
of the module, just below the fuse. The terminal is arranged with two hot  
pins (1 and 2), a keying pin (3), and two neutral pins (4 and 5), for ease of  
“daisy chaining” power from one module to another. Incoming power can be  
verified by measuring the voltage between the fuse bottom (hot side) and the  
connector's neutral (pins 4 or 5). The voltage should read between 97.8 to  
132.2 volts AC rms. Refer to Figure 7. (The 15% voltage criteria is most  
important for the EXV module's operation, as the Electronic Expansion  
Valve's available torque is directly related to this value).  
The fuses can be checked by looking for the supply voltage at the top of the  
fuse (fused side) with respect to the connector neutral.  
If some modules have power and some do not, the “daisy chain” wiring or  
power connections should be suspected. Refer to the Unit Wiring diagrams  
for the specifics on the power wiring.  
Generally a power loss to a particular module will first be noticed as a  
communications loss with that module. The module can be identified by  
analysis of the IPC diagnostics as displayed by the CPM. Refer to Section 2  
Interprocessor Communication for more information about Communication  
(IPC) diagnostics. If the CLD's display is blank, 24 VAC power should be  
checked at the CLD.  
RLC-SVD03A-EN  
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Module Power and Miscellaneous I/O  
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AC Power Connection To Modules  
Clear Language Display (CLD) 1U6 Keypad Overview  
Local operator interface with the system is accomplished using the 16 keys  
on the front of the Clear Language Display panel. The readout screen is a two  
line, 40 character liquid crystal display with a backlight. The backlight allows  
the operator to read the display in low-light conditions. The depression of any  
key will activate the backlight. The backlight will stay activated for 10 minutes  
after the last key is pressed. At 10 F or below the backlight will stay activated  
continuously.  
The keys are grouped on the keyboard by the following functions (refer to  
- Select Report Group  
- Select Settings Group  
- Selection Keys  
- Stop & Auto Keys  
42  
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Module Power and Miscellaneous I/O  
Figure 8  
Operator Interface Adaptive Control  
Select Report Group  
This group of four keys allows the operator to select and view the following  
reports:  
- Custom Report  
- Chiller Report  
- Refrigerant Report  
- Compressor Report  
The Custom Report is the only report of the four that is defined by the  
operator. Any display under the other three reports can be added to the  
Custom Report by pressing the plus  
key while the desired read-out is on  
the display. A maximum of 20 entries can be contained under the Custom  
Report. Items can be deleted from the Custom Report by pressing the minus  
key when the desired read-out is on the display. The operator must be in  
the Custom Report menu to delete the desired item.  
The Chiller Report, Refrigerant Report and Compressor Report are informa-  
tional reports that give current status. Each report and its contents are  
discussed in detail on the following pages.  
RLC-SVD03A-EN  
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When any of the four report keys are pressed, the first readout on the display  
will be the header. The header identifies the title of the report and summa-  
rizes the items in the report.  
The Next key and Previous key allow the operator to scroll up and down  
through the display items listed under the report menus. When the last item  
of a report is displayed and the Next key is pressed, the display will wrap  
around to the header of the report. When the first item of a report is  
displayed and the Previous key is pressed, the display will wrap around to the  
last item.  
Select Settings Group  
The first three keys on the second row - Operator Settings, Service Settings  
and Service Tests - allow the operator to adjust various setpoints and perform  
various tests. Certain items in these groups are password protected. Refer to  
the Password section for additional information.  
When a setpoint key is pressed, a header will be displayed. The setpoint  
headers identify the available items and setpoint functions.  
The Next and Previous keys function in the same manner as that described in  
Selected Report Group, above.  
Setpoint values are incremented by pressing the Plus  
key and decre-  
mented by pressing the Minus key. Once a setpoint is changed, the Enter  
key must be pressed to save the new setpoint. If the Cancel key is pressed,  
the setpoint value on the display will be ignored and the original setpoint will  
remain.  
Passwords  
Passwords are needed to enter into the Service Setup Menu and the  
Machine Configuration Menu. Both of these menus are accessed through the  
Service Settings key. If access into these menus is necessary, follow the list  
of steps below:  
1. Press Service Settings  
2. Press Next until the readout in the display is:  
Password Required For Further Access “Please enter Password”  
3. To enter into the Service Setup Menu, press:  
Enter  
Enter  
4. To enter into the Machine Configuration Menu, press:  
Refer to RTAA or RTWA IOM for the list of items found in the Service Setup  
Menu and Machine Configuration Menu.  
Select Report Group and Select Settings Group Flowcharts  
Refer to RTAA or RTWA IOM for the display readouts found under each  
menu. The first block of the flowchart is the header which is shown on the  
display after the menu key is pressed. For example:  
Press Chiller Report and the readout on the display will be  
CHILLER RPRT:STATUS, WTR TEMPS & SETPTS  
“PRESS (NEXT) (PREVIOUS) TO CONTINUE”  
44  
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Press Next to move down through the Chiller Report. As shown in the  
figures, the flowchart explains the conditions that the UCM looks at to  
determine which readout is to be displayed next. For example:  
Press Chiller Report to display the header  
Press Next to display  
MODE:  
[OPERATING MODE]  
[SETPT SOURCE]  
REQUESTED SETPOINT SOURCE:  
Press Next to display  
COMPRESSORON  
CIRCUITS LOCKED OUT  
Press Next to display  
ACTIVE ICE TERMINATION SETPOINT  
or  
ACTIVE CHILLED WATER SETPOINT  
The UCM will determine which screen will be displayed after looking at the  
current Operating Mode. If the Operating Mode is “Ice Making” or “Ice  
Making Complete, ACTIVE ICE TERMINATION SETPOINT will be displayed.  
Otherwise, ACTIVE CHILLED WATER SETPOINT will be shown.  
The flowcharts also list the setpoint ranges, default options and a brief  
description of the item, when necessary. This information is shown in the  
lefthand column of the page, adjacent to the appropriate display.  
Auto/Stop Keys  
The chiller will go through a “STOPPING” mode when the Stop key is  
pressed, if a compressor is running. This key has a red background color  
surrounding it, to distinguish it from the others.  
If the chiller is in the Stop mode, pressing the Auto key will cause the UCM to  
go into the Auto/Local or Auto/Remote mode, depending on the Setpoint  
Source setting. The Auto key has a green back-ground color.  
When either the Auto or Stop key is pressed, Chiller Operating Mode (Chiller  
Report Menu) will be shown on the display.  
Power Up  
When power is first applied to the control panel, the Clear Language Display  
goes through a self-test. For approximately five seconds, the readout on the  
display will be  
SELF TEST IN PROGRESS  
During the self-test, the backlight will not be energized. When the tests are  
successfully complete, the readout on the display will be  
6200 xxxx-xx  
[TYPE] configuration  
Updating Unit Data, Please Wait  
RLC-SVD03A-EN  
45  
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Module Power and Miscellaneous I/O  
When updating is successfully completed, the system will default to the first  
display after the Chiller Report header:  
MODE:  
OPERATING MODE]  
[SETPT SOURCE]  
REQUESTED SETPOINT SOURCE:  
and the backlight will be activated.  
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TB1-1,2  
IPC Communications  
19.2K Baud serial data  
5 V signal level  
Refer to Interprocessor Communication (IPC)  
TB2-1,2  
24 VAC Power  
18-30 VAC, neither side grounded  
Figure 9  
CLD Module (1U6)  
LEDs  
There are four LEDs located to the right of TB1 of the CLD module. See  
Figure 9. The ST LED should be on continuously. If it blinks, it indicates the  
processor is repeatedly being reset. The +5 VDC LED should also be on  
continuously. It will go out if power drops below normal operating voltage.  
The TX LED should blink every second or two, as the CLD transmits on the  
IPC. The RX LED should blink continuously, indicating that other modules are  
communicating.  
Chiller Module (CPM) (1U1)  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
46  
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Module Power and Miscellaneous I/O  
Test Points  
There are two test points associated with the CPM module. They are easily  
read with a DC voltmeter by probing the PC board solder pads found in the  
upper left hand corner of the module. The positive meter lead should be  
connected to the pad while referencing the negative meter lead to the board  
edge ground plane.  
NOTE: Don't use the aluminum module enclosure as a reference as it has  
an anodized surface with insulating properties.  
The DC voltages shall be within the tolerance specified below. If not replace  
the module.  
TP1: + 5 volts DC 5%  
TP2: +12 volts DC 5%  
RLC-SVD03A-EN  
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° TP1 + 5V  
° TP2 +12V  
J5-1  
J5-2  
J5-3  
J5-4  
J5-5  
115V H  
115V H  
— KEY (N/C)  
115V N  
115V N  
IPC (+) —  
IPC (-) —  
IPC (+) —  
IPC (-) —  
J1-4  
J1-3  
J1-2  
J1-1  
TB3-1 — CHILLED  
WATER FLOW  
TB3-2 — SWITCH  
H
I
G
H
MANUF.  
USE ONLY  
NO  
NO  
J2-2  
J2-1  
OUTDOOR AIR —  
TEMP  
TB1-1  
TB1-2  
TB3-3 — EXTERNAL  
AUTO/STOP  
V
0
EMERGENCY —  
STOP  
TB1-3  
TB1-4  
TB3-4 — INPUT  
L
T
A
G
E
L
0
W
NNS —  
NNS —  
TB1-5  
TB1-6  
TB4-1 — COM ALARM  
TB4-2 — (NO) RELAY  
TB4-3 — (NC)  
NOT USED  
NOT USED  
CEWT —  
CEWT —  
TB2-1  
TB2-2  
V
0
L
T
A
G
E
I
{
{
N
P
U
T
S
TB4-4 — COM COMPR  
TB4-5 — (NO) RUN  
RELAY  
CLWT —  
CLWT —  
TB2-3  
TB2-4  
EVAP ENTERING —  
WATER TEMP —  
J3-5  
J3-4  
TB4-6 — COM MAX CAPACITY  
TB4-7 — (NO) RELAY  
0
U
T
P
U
T
I
KEY  
J3-3  
N
P
U
T
S
TB4-8 — COM EVAP PUMP  
TB4-9 — (NO) RELAY  
EVAP LEAVING —  
WATER TEMP —  
J3-2  
J3-1  
TB4-10 — COM SPARE  
TB4-11 — (NO) RELAY  
S
AUX TEMP —  
KEY (N/C)  
AUX TEMP —  
J6-3  
J6-2  
J6-1  
U/O VOLT TRANSF —  
KEY  
U/O VOLT TRANSF —  
J4-3  
J4-2  
J 4-1  
Figure 10 CPM (Chiller) Module (1U1)  
I/O terminals  
For the checkout of the I/O, refer to the block diagram of the module in Figure  
10 and the Chiller Wiring Diagrams for both high and low voltage circuits. All  
voltages are measured differentially between terminal pairs specified unless  
otherwise indicated. The first terminal in the pair is the positive (or hot)  
terminal. Voltages given are nominals and may vary by 5%. Unregulated  
Voltages (unreg) or 115 VAC voltages may vary by 15%.  
48  
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Table 16  
CPM (Chiller) Nominal Terminal Input and Output (1U1)  
Terminal  
Designation  
Description  
of Circuit  
Normal Terminal Voltages  
for Various Conditions  
J1-4 to 3 to CLD IPC Communications  
J1-2 to 1 to 1U5  
19.2 kbaud serial data, 5 volt signal level.  
Refer to Interprocessor Communication ([PC)  
J2-2, 1  
Manufacturing Address Use Only  
+5 VDC No connection intended.  
TB1-1, 2  
TB1-3, 4  
Outdoor Air Temperature  
Emergency Stop  
Refer to Temperature Sensor Checkout  
open: 20.6 VDC unreg: Stopped  
closed: 0 VDC: Normal  
Must be jumpered if this feature is not used.  
TB1-5, 6  
NNS (Not Used)  
open: 20.6 Vdc unreg: Normal  
closed: 0 VDC: Setback  
TB2-1, 2  
TB2-3, 4  
J3-5, 4  
ECWT (Not Used)  
LCWT (Not Used)  
N/A  
N/A  
Entering Evaporator Water Temper-  
ature  
Refer to Temperature Sensor Checkout  
J3-2, 1  
J4-3, 1  
Leaving Evaporator  
Water Temperature  
Refer to Temperature Sensor Checkout  
Under/Over Voltage  
Transformer Input  
Refer to Under/Over Voltage Transformer  
Checkout Procedure  
J5-1 or 2  
Input Power  
to J5-4 or 5  
J6-3, 1  
Auxiliary Temp. Input  
Refer to Temperature Sensor Checkout  
TB3-2, 1  
Chilled Water  
open: 115VAC: No Flow  
Flow Switch Input  
closed: < 5VAC: Flow (Software imposes a 6 second delay  
to respond to opening or closing.  
TB3-3,4  
TB4-1, 2  
TB4-1, 3  
TB4-4, 5  
Chilled Water Demand Switch and  
External Auto Stop  
open: 115VAC: Stop  
closed: < 5VAC: Auto  
Chiller Alarm or Alarm Ckt 1  
(N.O. Contact)  
Dry SPDT Contact closes on Alarm, intended for 115 VAC  
customer control circuit.  
Chiller Alarm or Alarm Ckt 1  
(N.O. Contact)  
Dry SPDT Contact opens on Alarm, intended for 115 VAC  
customer control circuit.  
Unit Running, Alarm Ckt 2, or  
Ckt 1 Running  
(N.O. Contact)  
Dry SPDT Contact closes on Unit Running,  
Alarm Ckt 2 or Ckt 1 Running, intended for  
115 VAC customer control circuit.  
TB4-6, 7  
TB4-8, 9  
Maximum Capacity or Ckt 2 Running  
(N.O. Contact)  
Dry SPDT Contact closes on Maximum Capacity or Ckt 2  
Running, intended for 115 VAC customer control circuit.  
Chilled Water Pump Starter  
(N.O. Contact)  
Dry SPST Contact closes when Chilled Water  
Demand Switch is closed, opens after time  
delay specified in UCM 115 VAC customer control circuit.  
TB4-10, 11  
Spare Relay}  
Dry SPST contact. 115 VAC customer control circuit.  
(N.O.) Contact  
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Module Power and Miscellaneous I/O  
Options Module (CSR) (1U2)  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
Test Points  
There are three test points associated with the CSR module. They are easily  
read with a DC voltmeter by probing the PC board solder pads found in the  
upper left hand corner of the module. The positive meter lead should be  
connected to the pad, while referencing the negative meter lead to the board  
edge ground plane.  
Note: don't use the aluminum module enclosure as a reference as it has  
an anodized surface with insulating properties. The DC voltages shall be  
within the tolerance specified below. If not replace the module.  
TP1: + 5 volts DC 5%  
TP2: + 6 volts DC 5%  
TP3: +12 volts DC 25%  
Switch SW-1  
Switch SW1 is used to configure the External Chilled Water Setpoint input  
and the External Current Limit Setpoint input for either a 2-10VDC, or a 4-  
20ma signal. With the respective switch closed (on), a shunt resistor is  
switched into the input circuit to provide a fixed low value input impedance  
(499 ohms) for current loop operation. With the switch off, the input  
impedance is differentially 40Kohms.  
External Setpoint Inputs (4-20ma/2-10VDC)  
The chiller setpoint source should always be set to LOCAL when using any  
external inputs, except a Tracer. When using a Tracer, always set the chiller  
setpoint source to the Tracer mode. The setpoint source can be found in the  
Operator Settings Menu.  
These inputs accept either an isolated 4-20mA or 2-10VDC signal from an  
external controller or programming resistor connected to an internal +5V  
source. The switches SW1-1 and SW1-2 are used to select either the voltage  
or current option for External Chilled Water Setpoint and External Current  
Setpoint respectively. See Test Points, above. Alternately, either input may be  
used with a resistor or potentiometer.  
NOTE: Note: For proper operation, the 4-20mA/2-10VDC inputs are required  
to be used with a current or voltage source that:  
1. Is isolated (floats) with respect to ground, or  
50  
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Module Power and Miscellaneous I/O  
2. Has its negative terminal tied to chassis ground.  
If the intended source does not meet the above requirement, an isolation  
module must be used  
The 4-20mA/2-10VDC inputs may be tested in the following ways:  
1. Enable External Chilled Water Setpoint and/or External Current Limit Set-  
point in the Operator Settings Menu. Advance display to Active Chilled  
Water Setpoint or Active Current Limit Setpoint to observe the respective  
setpoint in the Chiller Report.  
2. With all wiring in place, apply an external voltage or current to the Exter-  
nal Chilled Water Setpoint inputs (TB1-4 & 5) or the External Current Limit  
Setpoint (TB1-7 & 8). The voltage measured at the terminals and the  
resulting setpoint, as read on the CLD, should agree with the Table 17 for  
Chilled Water Setpoint inputs and Table 18 for Current Limit Setpoints  
inputs. Be sure to wait long enough when reading the display as the val-  
ues are slew rate limited.  
3. Disconnect all wiring to these inputs. The setpoints should slew back to  
the chiller's Front Panel settings.  
4. Disconnect all wiring and install fixed resistors of values near those  
shown in the following tables across TB1-3,5 or TBl-6,8. The resulting set-  
points should agree with the table values.  
Table 17  
Input Values vs. External Chilled Water Setpoint  
INPUTS  
Resulting Chilled  
Resist (ohms)  
94433  
68609  
52946  
42434  
34889  
29212  
Current (ma)  
4.0  
Voltage (Vdc)  
Water Setpt (F) 4F  
2.0  
2.6  
3.2  
3.9  
4.5  
5.1  
5.7  
6.3  
6.9  
7.6  
0.0  
5.2  
5.0  
6.5  
10.0  
15.0  
20.0  
25.0  
30.0  
35.0  
40.0  
45.0  
50.0  
55.0  
60.0  
7.7  
8.9  
10.2  
11.4  
24785  
21236  
12.6  
13.8  
15.1  
16.3  
17.5  
18327  
15900  
13844  
8.2  
8.8  
9.4  
12080  
10549  
18.8  
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Table 18  
Input Values vs. External Current Limit Setpoint  
INPUTS  
Resist (ohms) Current (ma)  
Resulting Current  
Limit Setpt (%RLA) 5%  
Voltage (Vdc)  
49000  
29000  
19000  
13000  
9000  
6143  
4.0  
2.0  
3.0  
4.0  
5.0  
6.0  
7.0  
40  
6.0  
50  
8.0  
60  
10.0  
12.0  
14.0  
16.0  
18.0  
20.0  
70  
80  
90  
4010  
8.0  
9.0  
10.0  
100  
110  
120  
2333  
1000  
Setpoint Priority  
There are many ways in which the Chilled Water and Current Limit setpoints  
can be adjusted or reset when the Options Module is present in the Chiller  
control system. The following flow charts show how these methods are prior-  
itized and arbitrated under normal operating conditions. When abnormal  
conditions are present, such as loss of Tracer communications or out of range  
values on external setpoint inputs, the system will default to other methods.  
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“TRACER” implies Trane Integrated Comfort System remote device (ICS) using the digital communication link.  
“EXTERNAL” implies generic building automation system or process controller interface using a 4-20ma loop or a 2-10 VDC analog  
signal.  
Figure 11 Chilled Water Setpoint Arbitration  
RLC-SVD03A-EN  
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“TRACER” implies Trane Integrated Comfort System remote device (ICS) using the digital communication link.  
“EXTERNAL” implies generic building automation system or process controller interface using a 420ma loop or a 2-10 VDC analog  
signal.  
Figure 12 Current Limit Setpoint Arbitration  
54  
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ICS Communications  
ICS (Tracer) communication is handled the same as on previous products  
using the Trane proprietary Comm3 standard 1200 baud isolated serial  
communication link. The following are some things to check when experi-  
encing loss of ICS communications:  
1. If ICS control is desired, check that “Tracer” has been selected in Set-  
point Source of the Operator Settings Menu. In any case, the Tracer  
should be able to communicate to the chiller for monitoring purposes,  
regardless of the Setpoint Source selection. Refer to Figure 11 for a  
description of the normal operation of setpoint and setpoint reset arbitra-  
tion.  
2. Check for the proper ICS address in the Service Settings Menu and com-  
pare to the address programmed at the ICS device.  
3. Check for proper termination of the twisted pair communication link wir-  
ing to terminals TB2-1 and TB2-2 (or TB2-3 and TB2-4)  
4. Check for a diagnostic at the display indicating loss of IPC communica-  
tions with the Options module. This could indicate IPC bus problems or a  
dead Options module. (See Options Module (CSR) (1U2) on page 50). The  
Options module needs to receive 4 good packets of data from the CPM  
before it will talk on the ICS link.  
5. Check power to the Options module and the condition of the fuse. (See  
6. Check the Test Point voltages on the module. (See Test Points on page  
47).  
NOTE: The red LED on the module blinks each time a proper message or  
query is received from the Remote ICS device.  
I/O Terminals  
For the checkout of the I/O refer to the block diagram of the module on the  
following page and the Chiller Wiring Diagrams for low and high voltage  
circuits. All voltages are measured differentially between terminal pairs  
specified unless otherwise indicated. The first terminal in the pair is the  
positive (or hot) terminal. Voltages given are nominals and may vary by 5%.  
Unregulated Voltages (unreg) may vary by 25% and 115 VAC voltages may  
vary by 15%.  
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Table 19  
Terminal  
CSR Normal Terminal Voltages for Options Module 1U2  
Description  
Normal Terminal Voltages  
for Various Conditions  
Designation of Circuit  
J1-4 to 3  
IPC Communications  
19.2 kbaud serial data, 5 volt signal level.  
or J1-2 to 1  
Refer to Interprocessor Communication Link (IPC).  
J2-2, 1  
Manufacturing  
+5 VDC No connection intended.  
Address Use Only  
TB1-3  
+5V Source for use with  
Resistor programming of CW  
setpoint  
+5VDC open circuit with respect to chassis ground.  
TB1-3, 5  
TB1-4, 5  
TB1-6  
Ext. Chilled Water Setpoint  
(Resistive option)  
+5VDC open circuit.  
Ext. Chilled Water Setpoint  
(Current or Voltage option)  
+5V Source for use with  
Resistor programming of CL  
setpoint  
TB1-6, 8  
TB1-7, 8  
TB1-9, 10  
Ext. Current Limit Setpoint  
(Resistive option)  
Ext. Current Limit Setpoint  
(Current or Voltage option)  
Unused  
TB2A-1,2  
or TB2B-3,4  
Serial Comm.Input  
Refer to Section 2, ICS Communications.  
115 VAC, Refer to Power Supply on page 41.  
J6-1 or 2  
Input Power  
to J6-4 or 5  
Dip Switch  
SW1-1  
External Chilled Water Setpoint Off for 2-10 VDC input.  
Dip Switch  
On for 4-20 mA input.  
Dip Switch  
SW1-2  
External Current  
Limit Setpoint  
Dip Switch  
Off for 2-10 VDC input.  
On for 4-20 mA input.  
56  
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° TP1 +5V  
° TP2 + 6V  
° TP2 + 12V  
J6-1  
J6-2  
J6-3  
J6-4  
J6-5  
115VAC HOT  
115VAC HOT  
— KEY (N/C)  
— NEUTRAL  
— NEUTRAL  
IPC (+) —  
IPC (-) —  
IPC (+) —  
IPC (-) —  
J1-4  
J1-3  
J1-2  
J1-1  
MANUF.  
USE ONLY  
NO CONN. —  
NO CONN. —  
J2-2  
J2-1  
1
2
SW1  
ON  
H
I
L
0
W
ZONE TEMPERATURE —  
RESET/ICE MAKING —  
TB1-1  
TB1-2  
G
H
EXTERNAL CHILLED +5V —  
WATER 4-20mA/2-10V —  
TB1-3  
TB1-4  
TB1-5  
V
0
L
V
0
L
SETPOINT  
COM —  
T
A
G
E
T
A
G
E
EXTERNAL CHILLED +5V —  
LIMIT 4-20mA/2-10V —  
TB1-6  
TB1-7  
TB1-8  
SETPOINT  
COM —  
HPO —  
TB1-9  
TB1-10  
I
I
N
P
U
T
S
N
P
U
T
S
LED 1  
COMM3 A —  
COMM3 A —  
COMM3 B —  
COMM3 B —  
TB2-1  
TB2-2  
TB2-3  
TB2-4  
Figure 13 CSR (Options) Module (IU2)  
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Electronic Expansion Valve Module (EXV) (1U3)  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
Valve Operation  
The electronic expansion valve is an electronic flow device that replaces the  
thermostatically controlled expansion valve and liquid line solenoid. A  
sectional view of the valve is shown in Figure 16 and Figure 17.  
The control method uses two sensors that measure the temperature  
difference between the inlet and outlet evaporator refrigerant temperature.  
This enables the system to control the temperature difference and maintain  
superheat.  
The SEO-70 and SEO-100 valves were used on units until November 1, 2003.  
All units built after that date will have a SEHI-100 valve installed.  
The module for the SEHI is different because the new valve uses a two coil  
instead of three. The locations of the keying pins are different on the module.  
Design Sequence Information, digit 10-11 of the unit model number.  
RTWA/UA A0 - E0  
SEO Valve  
RTWA/UA F0 and later SEHI Valve  
RTAA A0 - P0  
SEO Valve  
SEHI Valve  
RTAA Q0 and later  
NOTE: For units with remote evaporator use 16 AWG wire.  
SEO-70 and SEO-100 Valve  
The valve is a stepper-motor type, direct acting valve. It uses a three-phase  
motor (not to be confused with3-phase AC), with each phase having 40 ohms  
of resistance.  
The supply voltage (24 VDC) is switched on and off to each phase, to step the  
valve open or closed. Each step is 0.0003" of stroke, with a full stroke of 757  
steps.  
The motor's rotary motion is translated into linear movement through a lead  
screw and drive coupling arrangement. A clockwise rotation of the motor  
shaft creates a downward movement of the drive coupling. This presses the  
pushrod and piston against the return spring, opening the valve. A counter-  
clockwise rotation of the motor shaft retracts the drive coupling. The return  
spring moves the piston and pushrod in the closing direction.  
58  
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A “FLAG” stop is located at either end of the threaded portion of the motor  
shaft. The stops interfere with the milled flag on the drive coupling, restricting  
rotation of the motor shaft and producing a clicking sound when the valve is  
driven fully OPEN or CLOSED.  
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Figure 14 SEO 70, 100 Electronic Expansion Valve Cut Away View  
SEHI-100 Valve  
The valve is a stepper-motor type, direct acting valve. It uses a two-phase  
motor, with each phase having 75 ohms of resistance.  
The supply voltage (12 VDC) is switched on and off to each phase, to step the  
valve open or closed. Each step is 0.00007" of stroke, with a full stroke of  
6376 steps.  
The step motor used in the SEHI valve is a permanent magnet rotor type.  
Each step creates a 3.6° rotation of the rotor. This rotation is increased in  
torque and reduced in speed by a 12.25:1 gear train. Final rotation is  
converted to linear motion by the use of a lead screw and threaded drive  
coupling. Forward motion of the motor extends the drive coupling and pin,  
which moves the valve to the closed position. Backward rotation of the motor  
retracts the drive coupling and pin modulating the valve in the opening  
direction. Full forward or backward travel, while the valve is assembled, is  
limited by the valve seat in the closed position or an upper stop in the open  
direction. A slight clicking sound may be heard at either of these two  
positions and does no harm to the valve or drive mechanism.  
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Figure 15 SHEI Valve  
Electronic Expansion Valve Location  
The valve should be installed with the motor in a vertical position, or no  
greater than 45° from vertical, as shown in Figure 16. This will prevent oil  
logging and the possibility of contamination reaching the motor cavity. The  
valve should also be installed as close to the evaporator as possible.  
60  
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Figure 16 Electronic Expansion Valve Location  
Test Points  
There is only one test point associated with the EXV module. It is easily read  
with a DC voltmeter by probing the PC board solder pad found in the upper  
left hand corner of the module. The positive meter lead should be connected  
to the pad while referencing the negative meter lead to the board edge  
ground plane.  
NOTE: Don't use the aluminum module enclosure as a reference as it  
has an anodized surface with insulating properties. The DC voltage shall  
be within the tolerance specified below. If not replace the module.  
TP1: +5 volts DC 5%  
EXV Test  
The EXV module has a built in test which is designed to allow the service  
technician to confirm a problem with the EXV control system and to identify  
which of the components of the system (the Valve/Stepper Motor assembly,  
the EXV Module, or the interconnecting wiring) is at fault. The directions to  
perform this test are given below:  
EXV Test Procedure  
1. Place the Chiller in the “STOP” mode using the Stop Button on the CLD.  
2. Determine which refrigeration circuit is associated with the EXV valve you  
want to test. Advance to the EXV TEST display in the Service Tests Menu.  
3. Press the  
or  
keys to change the displayed “d” to an “E, which  
will enable or initiate the preprogrammed procedure. Display will auto-  
matically return the item to disabled when the test is completed.  
Electrical Integrity Test  
4. Initially the UCM will perform an Electrical Integrity test on the valve's  
stepper motor phases and associated wiring. If a failure is detected, it will  
report a diagnostic indicating “EXV Elect. Drive CKT” at this time. This  
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diagnostic suggests that there is a problem with the valve or the valve  
wiring. To confirm this, it is necessary to continue the procedure. The  
Electrical Integrity test will be completed in about 2 seconds. Regardless  
of whether or not a diagnostic occurs, the UCM will proceed with the  
stroke timing portion of the test.  
Stroke Timing Test  
5. At this time the UCM will drive the valve closed. Thus the total closing  
time will be 25 seconds. Due to mechanical characteristics of the valve, it  
will make a clicking sound when it reaches its end stops (either full open  
or full closed). In most cases, the valve will already be closed when this  
test is initiated, so a normally operating valve will exhibit the clicking for  
approximately 25 seconds.  
NOTE: The loudness of the clicking varies from one valve to another and  
ambient noise can muffle the clicking sound. Therefore, it may be necessary  
to use a tool to aid in the hearing of the clicking (such as a screwdriver held  
between the EXV and the ear.)  
6. Following the 25 seconds of closing, the valve will immediately be  
stepped open for the same period of time (25 seconds). As soon as the  
valve begins its opening movement the clicking should stop. while it  
moves through its stroke. The service technician would then note the  
time between when the clicking stopped until the time it restarts. This  
would give an indication of the opening stroke time.  
NOTE: If the valve and switching circuitry is operating properly, the silent  
valve movement should last for approximately 15 seconds.  
End of stroke clicking should then be heard for 10 seconds.  
7. The module will then reverse direction and the valve will be stepped  
closed again for a full 25 seconds. Since the valve should have started  
from the full open position, the time to stroke closed should be noted and  
it should be approximately the same as the opening time above. If both  
opening and closing stroke times are correct to within 5 seconds of the  
time specified, no further testing is required. If any valve fails this test,  
the service technician should perform the EXV Valve Winding Resistance  
Check, steps 8 thru 10 below.  
SEO EXV Valve Winding Resistance Check  
1. Disconnect the appropriate EXV valve from the pin header of the EXV  
module.  
2. With a digital ohm-meter, check the resistance of the valve windings and  
associated leads/connector by measuring the resistance of pin pairs at  
the connector plug. Pin pairs are #5 and #3, #5 and #2, and #5 and #1 for  
Circuit 1. Pin numbers are indicated by corresponding position # on the  
board or by the raised numbers of the connector block. The resistances  
should all be 40 ohms 4 ohms at 75F winding temperature. (At a valve  
winding temp of 148F the resistance would be no more than 54 ohms; at  
a valve winding temp of 32F the resistance would be no less than 33  
ohms).  
62  
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3. Check the resistance from each of the three phase pins (J4-3, J4-2, and  
J4-1) to the board edge GND, with the connector unplugged. This resis-  
tance should be between 100K and 200K ohms.  
If the valve/wiring/connector combination fails the above tests, suspect the  
connector or the wiring first. At the valve for circuit #1; wire color black corre-  
sponds to pin #5, red to pin #3, white to #2 and green to #1. For circuit #2:  
black to pin #6, red to pin #4, white to #2, and green to pin #1. Refer to Table  
20 and use the pass-fail results above to determine the prescribed action.  
SEHI EXV Valve Winding Resistance Check  
1. Disconnect the appropriate EXV valve from the pin header of the EXV  
module.  
2. With a digital ohm-meter, check the resistance of the valve windings and  
associated leads/connector by measuring the resistance of pin pairs at  
the connector plug. Pin pairs are #5 and #4, #2 and #1 for Circuit 1 and #6  
and #5, and #2 and # 1 for Circuit 2. Pin numbers are indicated by corre-  
sponding position # on the board or by the raised numbers of the connec-  
tor block. The resistances should all be 75 ohms 10 ohms.  
3. Check the resistance from each lead to the board edge GND, with the  
connector unplugged. This resistance should be greater than 1 meg  
ohms.  
If the valve/wiring/connector combination fails the above tests, suspect the  
connector or the wiring first. At the valve for circuit #1; wire color black corre-  
sponds to pin #1, red to pin #5, white to #2 and green to #4. For circuit #2:  
black to pin #1, red to pin #6, white to #2, and green to pin #5. Refer to Table  
20 and use the pass-fail results above to determine the prescribed action.  
Table 20  
Test Results Logic Table  
*
STROKE TIMING RESISTANCE PRESCRIBED ACTION  
ELECT. INTEGRITY TEST  
PASS  
PASS  
FAIL  
FAIL  
PASS  
FAIL  
FAIL  
NOT REQ.  
PASS  
FAIL  
VALVE/BOARD ARE WORKING PROPERLY -  
NO ACTION REQ.  
PASS  
PASS  
FAIL  
FAIL  
FAIL  
VALVE IS MECHANICALLY STUCK -  
REPLACE/REPAIR VALVE  
HIGHLY UNLIKELY CONDITION  
RETEST-REPLACE MODULE  
PASS  
PASS  
FAIL  
HIGHLY UNLIKELY CONDITION  
RETEST-NO ACTION REQ.  
CHECK CONNECTION AT MODULE  
RETEST-REPLACE MODULE  
SUSPECT WIRING, PLUG OR VALVE-  
REPLACE/REPAIR SAME  
*.INDICATION OF PASS OR FAIL OF THIS TEST IS DISPLAYED AT THE CLD IN THE DIAGNOSTICS MENU.  
Solder Techniques for Installation  
It is not necessary to disassemble the valve when soldering to the  
connecting lines. Most commonly used types of solder (eg. Sil-Fos, Easy-  
Flow, PhosCopper or equivalent) are satisfactory. Regardless of the solder  
RLC-SVD03A-EN  
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used, it is important to direct the flame away from the valve body. See Figure  
17. A wet cloth should be wrapped around the body during soldering to  
provide extra protection. This will help prevent overheating and damage to  
the synthetic seals and subsequent degradation in valve performance. Valves  
are shipped in the full-open position, to allow for the flow of inert gas  
while soldering.  
Figure 17 Electronic Expansion Valve Soldering  
SEO Electronic Expansion Valve Servicing  
The procedures listed below are to. be followed for proper disassembly,  
inspection, cleaning and reassembly to the valve. The valve does not need to  
be removed from the refrigerant piping before servicing.  
1. Before disassembly of the valve, be sure the refrigerant pressure in the  
system has been reduced to a safe level (0 psig) on both sides of valve.  
See RTAA-SB-10 for preferred refrigerant handling in this area.  
ƽ WARNING  
Hazardous Voltage w/Capacitors!  
Disconnect all electric power, including remote disconnects  
before servicing. Follow proper lockout/tagout procedures to  
ensure the power cannot be inadvertently energized. For variable  
frequency drives or other energy storing components provided by  
Trane or others, refer to the appropriate manufacturer’s literature  
for allowable waiting periods for discharge of capacitors. Verify  
with an appropriate voltmeter that all capacitors have discharged.  
Failure to disconnect power and discharge capacitors before  
servicing could result in death or serious injury.  
Note: For additional information regarding the safe discharge of  
capacitors, see PROD-SVB06A-EN or PROD-SVB06A-FR  
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2. Disconnect all the line voltage to the power supply of this unit.  
3. Refer to the exploded view in Figure 18 while performing the remaining  
instructions.  
ƽ CAUTION  
Prevent Injury!  
Refer to Figure 18. The pushrod is under spring pressure and will  
be accelerated out of the top or bottom of the valve body  
assembly if the activator assembly or bottom cap is removed.  
When unscrewing either the activator assembly or bottom cap,  
make sure these assemblies are kept in line with the valve body  
and moved away from the valve body very slowly in the vertical  
direction, until you feel the pressure is relieved from the pushrod.  
At this time hold the pushrod with one hand and then move the  
activator or bottom cap away from the valve body. * Do not try to  
remove either the activator assembly or bottom cap under any  
system pressure. System pressure must be at 0 psig on both  
sides of the valve before attempting any disassembly of  
this valve. Failure to slowly relieve spring pressure may result in  
minor to moderate injury.  
4. Remove the actuator assembly from the valve body using large hex nut to  
turn.  
5. Remove pushrod and check for excessive wear or scratches. The pushrod  
must move freely in the valve body.  
6. Remove the bottom cap, spring and piston. Inspect these parts for for-  
eign matter and physical damage.  
7. Clean all parts with a suitable solvent and blow dry with clean com-  
pressed air.  
8. To reassemble, carefully install the piston, spring and bottom cap. Be  
sure that the piston nose guides are on the inside diameter of the port.  
The seating surface may be damaged if the piston is improperly  
installed.  
9. Check that the sealing surfaces are free of foreign material or nicks that  
may prevent a leak-tight joint. Tighten the bottom cap approximately 1/8  
turn past hand tight to seal the knife edge joint.  
10. Place the pushrod in the valve body. Press the pushrod down to open the  
valve and insure proper piston installation. Approximately 8 ft.-lbs. are  
required to open the valve. If the valve cannot be opened, repeat steps 9  
and 10.  
Clean with a suitable solvent, blow dry with clean compressed air and  
replace the pushrod in the valve body.  
11. Before replacing the actuator assembly, be sure that all sealing surfaces  
are free of foreign material or nicks that may prevent a leak-tight joint.  
Carefully install the pushrod bonnet and thread the actuator assembly on  
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to the valve body until the sealing surfaces make contact. Tighten the  
actuator approximately 1/8 turn to seal the knife edge joint.  
12. The motor cap quad-ring may be replaced by removing the ferrule motor  
cap nut.  
Be sure that the motor cap does not rotate with the motor cap nut. The  
wires internal to the motor can be damaged.  
13. When reassembling, be sure that the internal wires do not get crimped  
between the motor cap and motor housing  
14. Pressurize the system and check for leaks.  
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Figure 18 SEO Electronic Expansion Valve Exploded View  
66  
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SEHI Electronic Expansion Valve Servicing  
The procedures listed below are to. be followed for proper disassembly,  
inspection, cleaning and reassembly to the valve. The valve does not need to  
be removed from the refrigerant piping before servicing. If the motor is found  
to be defective the entire motor assembly must be replaced.  
1. Before disassembly of the valve, be sure the refrigerant pressure in the  
system has been reduced to a safe level (0 psig) on both sides of valve.  
See RTAA-SB-10 for preferred refrigerant handling in this area.  
ƽ WARNING  
Hazardous Voltage w/Capacitors!  
Disconnect all electric power, including remote disconnects  
before servicing. Follow proper lockout/tagout procedures to  
ensure the power cannot be inadvertently energized. For variable  
frequency drives or other energy storing components provided by  
Trane or others, refer to the appropriate manufacturer’s literature  
for allowable waiting periods for discharge of capacitors. Verify  
with an appropriate voltmeter that all capacitors have discharged.  
Failure to disconnect power and discharge capacitors before  
servicing could result in death or serious injury.  
Note: For additional information regarding the safe discharge of  
capacitors, see PROD-SVB06A-EN or PROD-SVB06A-FR  
2. Disconnect all the line voltage to the power supply of this unit.  
3. Refer to the exploded view in Figure 19 while performing the remaining  
instructions.  
4. Unplug valve.  
5. Using the appropriate wrenches or a vice to properly support the valve  
body, remove the motor assembly from the valve body by loosening the  
lock nut. To prevent permanent damage to the motor, DO NOT attempt to  
disassemble the motor housing.  
NOTE: Regardless of whether the valve is in the system or in a vise,  
care must be taken to prevent distorting the valve parts when tight-  
ening.  
6. Verify that the new motor assembly is in the "OPEN" position.  
7. Lightly oil the threads and knife-edge on the new motor adapter. Carefully  
seat the adapter on the valve body.  
8. Engage and tighten the lock nut. One eighth turn more than hand tight is  
sufficient to achieve a leak proof seal.  
9. Pressurize the system and check for leaks.  
RLC-SVD03A-EN  
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Module Power and Miscellaneous I/O  
-OTORꢊ!DAPTOR  
!SSEMBLY  
0ISTON !SSEMBLY  
"ODY !SSEMBLY  
3IGHTGLASS  
Figure 19 SEHI Electronic Expansion Valve Exploded View  
68  
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Module Power and Miscellaneous I/O  
SEO Valve Module  
° TP1 +5V  
J6-1 — 115VAC HOT  
J6-2 — 115VAC HOT  
J6-3 — KEY (N/C)  
J6-4 — NEUTRAL  
J6-5 — NEUTRAL  
IPC (+) — J1-4  
IPC (-) — J1-3  
IPC (+) — J1-2  
IPC (-) — J1-1  
on  
off  
MANUF.  
USE ONLY  
NO CONN. — J2-2  
NO CONN. — J2-1  
SW-1  
L
0
W
H
I
G
H
LOW PRESSURE SIG.— J7-5  
SWITCH CIRCUIT 1 GND — J7-4  
KEY — J7-3  
LOW PRESSURE SIG. — J7-2  
SWITCH CIRCUIT 2 GND — J7-1  
V
0
L
V
0
SATURATED EVAPORATOR — J3-9  
TEMPERATURE CIRCUIT 1 — J3-8  
T
A
T
A
G
E
L
T
A
G
E
COMPRESSOR SUCTION — J3-7  
TEMPERATURE CIRCUIT 1 — J3-6  
N/C KEYING — J3-5  
SATURATED EVAPORATOR — J3-4  
TEMPERATURE CIRCUIT 2 — J3-3  
I
I
N
P
U
T
S
N
P
U
T
S
.
COMPRESSOR SUCTION — J3-2  
TEMPERATURE CIRCUIT 2 — J3-1  
GND — J4-5  
KEY (N/C) — J4-4  
PHASE 1 — J4-3  
ELECTRONIC  
EXPANSION  
O
VALVE  
CIRCUIT 1  
J4-2  
PHASE 2 —  
U
T
P
U
T
S
PHASE 3 — J4-1  
GND — J5-6  
KEY (N/C) — J5-5  
PHASE 1 — J5-4  
24 VDC Peak only  
when the Phase is  
being stepped.  
ELECTRONIC  
EXPANSION  
VALVE  
CIRCUIT 2  
KEY (N/C) — J5-3  
PHASE 2 — J5-2  
PHASE 3 — J5-1  
Figure 20 SEO Electronic Expansion Valve Module (1U3)  
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SEHI Valve Module  
° TP1 +5V  
J6-1 — 115VAC HOT  
J6-2 — 115VAC HOT  
J6-3 — KEY (N/C)  
J6-4 — NEUTRAL  
J6-5 — NEUTRAL  
IPC (+) — J1-4  
IPC (-) — J1-3  
IPC (+) — J1-2  
IPC (-) — J1-1  
on  
off  
MANUF.  
USE ONLY  
NO CONN. — J2-2  
NO CONN. — J2-1  
SW-1  
L
0
W
H
I
G
H
LOW PRESSURE SIG.— J7-5  
SWITCH CIRCUIT 1 GND — J7-4  
KEY — J7-3  
LOW PRESSURE SIG. — J7-2  
SWITCH CIRCUIT 2 GND — J7-1  
V
0
L
V
0
SATURATED EVAPORATOR — J3-9  
TEMPERATURE CIRCUIT 1 — J3-8  
T
A
T
A
G
E
L
T
A
G
E
COMPRESSOR SUCTION — J3-7  
TEMPERATURE CIRCUIT 1 — J3-6  
N/C KEYING — J3-5  
SATURATED EVAPORATOR — J3-4  
TEMPERATURE CIRCUIT 2 — J3-3  
I
I
N
P
U
T
S
N
P
U
T
S
.
COMPRESSOR SUCTION — J3-2  
TEMPERATURE CIRCUIT 2 — J3-1  
RED — J4-5  
GREEN — J4-4  
KEY (N/C) — J4-3  
ELECTRONIC  
EXPANSION  
O
VALVE  
J4-2  
WHITE —  
CIRCUIT 1  
U
T
BLACK — J4-1  
P
U
T
RED — J5-6  
GREEN — J5-5  
KEY (N/C) — J5-4  
KEY (N/C) — J5-3  
24 VDC Peak only  
when the Phase is  
being stepped.  
ELECTRONIC  
EXPANSION  
S
VALVE  
CIRCUIT 2  
WHITE — J5-2  
BLACK — J5-1  
Figure 21 SEHI Electronic Expansion Valve Module (1U3)  
I/0 terminals  
For the checkout of the I/O, refer to the block diagram of the EXV module in  
Table 21 and the Chiller Wiring Diagrams for both high and low voltage  
circuits. All voltages are measured differently between terminal pairs  
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specified, unless otherwise indicated. The first terminal in the pair is the  
positive (or hot) terminal. Voltages given are nominals and may vary by 5%.  
Unregulated Voltages (unreg) or 115 VAC voltages may vary by 15%.  
Table 21  
EXV Module Normal Terminal Voltages  
Terminal  
Designation  
Description  
of Circuit  
Normal Terminal Voltages  
for Various Conditions.  
J1-4 to 3  
IPC Communications  
19.2 kbaud serial data, 5 volt signal level.  
or J1-2 to 1  
Refer to Interprocessor Communication Link (IPC).  
J2-2, 1  
J3-9, 8  
J3-7, 6  
J3-4, 3  
J3-2, 1  
Manufacturing  
Address Use Only  
+5 VDC No connection intended.  
Refer to Temperature Sensor Checkout.  
Refer to Temperature Sensor Checkout.  
Refer to Temperature Sensor Checkout.  
Refer to Temperature Sensor Checkout.  
OVDC GND.  
Saturated Evap.  
Rfrg. Temp. CKT 1  
Compressor Suct.  
Rfrg. Temp. CKT 2  
Saturated Evap.  
Rfrg. Temp. CKT 2  
Compressor Suct.  
Rfrg. Temp. CKT2  
J4-51  
J4-31  
J4-21  
J4-11  
EXV CKT1 GND  
EXV CKT1 Phase 1  
EXV CKT1 Phase 2  
EXV CKT1 Phase 3  
Between 0 and 1 VDC when the phase is not being stepped. When  
the valve is being stepped, this signal is actually a 24.2 17% VDC  
peak square wave with a period of 60 msec and a 1/3 duty cycle  
low (On) and 2/3 duty cycle high (Off). An averaging DC voltmeter  
can be used to measure this voltage. The meter will show fluctua-  
tions but the average should be approximately 8 volts.  
J5-61  
J5-41  
J5-21  
J5-11  
J4-1, 2, 4,52  
J4-1, 2, 5, 62  
EXV CKT2 GND  
EXV CKT2 Phase 1  
EXV CKT2 Phase 2  
EXV CKT2 Phase 3  
EXV CKT 1  
OVDC GND.  
Same a CKT 1.  
Same as above.  
Same as above.  
10-12 VDC  
EXV CKT 2  
10-12 VDC  
J6-1 or 2  
Input Power  
115 VAC, Refer to Power Supply on page 41.  
to J6-4 or 5  
J7-5, 4  
Low Pressure  
Switch, Circuit 1  
Open = 12 VDC, Low Pressure Cutout  
Closed = 0 VDC, Normal  
J7-2, 1  
Low Pressure  
Switch, Circuit 2  
Open = 12 VDC, Low Pressure Cutout  
Closed = 0 VDC, Normal  
Note: On a power up or a front panel reset, the valve will always be driven closed for approximately 1000 steps. During this time,  
approximately 40 seconds, an alternating audible clicking sound can be observed on the valves  
1SEO Valve  
2SEHI Valve  
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Module Power and Miscellaneous I/O  
Compressor Module (MCSP) (1U4 AND 1U5)  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
Test Points  
There are two test points associated with the MCSP module. They are easily  
read with a DC voltmeter by probing the PC board solder pads found in the  
upper left hand corner of the module. The positive meter lead should be  
connected to the pad while referencing the negative meter lead to the board  
edge ground plane.  
NOTE: Don't use the aluminum module enclosure as a reference as it  
has an anodized surface with insulating properties.  
The DC voltage shall be within the tolerance specified below. If not replace  
the module.  
TP1: +5 volts DC 5%  
TP2: +12 volts DC 5%  
IPC Address Switch SW1  
Current Gain (or Overload) Dip Switch SW2  
The Compressor phase current inputs on the individual MCSP modules are  
“normalized” thru the proper setting on this switch. The term “Compressor  
Current Overload setting” is actually a misnomer. Instead the setting should  
be thought of as an internal software gain that normalizes the currents to a %  
RLA for a given CT and compressor rating. The true nominal steady state  
overload setting is fixed at 132%.  
The setting of the dip switch SW2 on each of the MCSP modules should  
match those of Table 18 for each compressor. Switch position SW2-1 is the  
Most Significant Bit. The decimal equivalent of this setting should also be  
verified in the Service Settings Menu, in the CLD display. If the programmed  
value does not agree with the dip switch setting for each of the MCSP's, an  
informational diagnostic will result. The compressors will be allowed to run,  
but default settings (the most sensitive possible) will be used for the internal  
software compressor current gains. Refer to Section 7 Current Transformer  
and Current Input Checkout for more details.  
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Module Power and Miscellaneous I/O  
Binary Inputs  
The binary inputs shown in Table 22 all use the same basic circuit. A pullup  
resistor to the 12V power supply is connected to the higher numbered input  
pin. The lower numbered pin is connected to ground. The voltage between  
the two pins is sensed by the microprocessor To check the input, measure  
the voltage between the two associated pins. With the external switch open,  
approximately 12 Vdc should be measured. With the switch closed, 0 Vdc  
should be measured.  
Temperature Inputs  
These inputs use Trane's standard thermistor,. an NTC device giving 10,000  
ohms at 25 C (75 F). Refer to Temperature Sensor Checkout, Table 4, for a  
table of temperature vs., resistance vs. voltage.  
Three measurements can be made:  
1. With the probe connected, the voltage across the input terminals may be  
measured. The voltage should agree with the table values in the Temper-  
2. The probe may be disconnected from the module and its resistance mea-  
sured. It should agree with the table values.  
3. With the probe disconnected, the terminal voltage may be measured  
with a high impedance voltmeter. It should be between 4.975 and 5.025  
Vdc. If the meter loads the input, a slightly lower voltage may be  
expected.  
Refer to Temperature Sensor Checkout for more details.  
Current Inputs  
The following tests may be used to check a current input circuit:  
1. With the compressor off, the AC voltage across the terminals with the  
current transformer connected should read 0 V The corresponding cur-  
rent as read on the CPM display should read 0.  
2. With the compressor on, the AC voltage across the terminals should  
agree with the data of Table 8. The %RLA read on the CPM display will  
depend on the setting of the gain switch. If the gain switch is set to 11111,  
the percent CT rating values should agree with the display. For any other  
switch setting, the gain factor as found in Table 9 must be taken into  
account using one of the following procedures:  
Start with the displayed %RLA. Multiply by .67 and divide by the gain  
where the gain is found in Table 16. The result is the percent CT rating.  
Use this and the Table 8 to find the corresponding terminal voltage.  
Start with an actual current measurement (such as from a clamp-on  
ammeter). Determine which CTs are being used and use the Table 8 to  
find the corresponding terminal voltage and percent CT rating. Multiply  
the percent CT rating by the gain and divide by.67 to find the %RLA that  
should be displayed.  
NOTE: If the MCSP gain switch and CPM gain setting do not agree, a  
diagnostic will be generated and the MCSP will continue operating using a  
default gain setting of 00000 (max gain). This will result in the MCSP thinking  
RLC-SVD03A-EN  
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Module Power and Miscellaneous I/O  
the currents are higher than actual and will show up as an error in the %RLA  
displayed by the CPM. The compressor will operate safely but may unload  
due to the current limit function.  
Refer to Current Transformers and Current Inputs for more details on  
operation and troubleshooting.  
Isolated Binary Input: Winding Temperature  
This input may be checked by disconnecting all wiring from the terminals and  
measuring the open circuit voltage. It should read between 10 and 15 Vac. A  
“Winding Temp. - Cprsr A or B” diagnostic should appear on the CPM's  
display depending on which compressor module it is. A jumper may then be  
placed across the input to short it out. After clearing diagnostics, the  
diagnostic should no longer be present. It a diagnostic continues to occur, the  
module needs replacement.  
Relay Outputs  
Compressor and Fan Control relays may be checked by measuring the voltage  
drop across the contacts. 115 Vac should be seen when the relay is off. 0 Vac  
should be seen when the relay is on. Before condemning a module for bad  
relays, make sure to check all diagnostics, power to the module, communica-  
tions, and the state of the high pressure cutout. Refer to the units' schematic  
wiring diagram for the control circuitry.  
Triac Outputs  
The Load/Unload triacs may be checked by measuring the voltage from  
terminals E7 or E8 to 115 V neutral, with a load connected. The triacs operate  
in the high side and switch 115 Vac power from J7-1 to either E7 or E8 to turn  
on the appropriate slide valve solenoid.  
When a triac is off, about 0 Vac should be measured on its terminal with the  
solenoid load connected. When it is on, the voltage should be close to 115  
Vac (the drop across the triac is about 1-2 volts). Except during a start or stop,  
the triacs normally pulse on for short durations (as low as 40mS) once every  
10 seconds. If chiller load is satisfied the triacs may not pulse. Because of  
this, it may be difficult to see the pulses on a meter. A low wattage 115 Vac  
test lamp may be of help.  
The best time to check the unload solenoid is immediately after a power-up  
reset. For the first 30 seconds after applying power, the unload solenoid  
should be on continuously. The next best time to check it is after the  
compressor starts. For the first 30 seconds after a start, the unload solenoid  
should be on continuously.  
Checking the load solenoid is more difficult. Shortly after a start, the  
compressor will usually start loading. If, however, water temperature is  
dropping rapidly enough, it will stay unloaded. It may take a while to begin  
seeing load pulses.  
Refer to on page 36, for a more detailed procedure on how to accomplish the  
load / unload solenoid and slide valve check on the MCSP and associated  
compressor.  
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I/O Terminals  
For the checkout of the I/O, refer to the block diagram of the MCSP module in  
Figure 22 and the Chiller Wiring Diagrams for both high and low voltage  
circuits. All voltages are measured differentially between terminal pairs  
specified unless otherwise indicated. The first terminal in the pair is the  
positive (or hot) terminal. Voltages given are nominals and may vary by 5%.  
Unregulated Voltages (unreg) or 115 VAC voltages may vary by 15%.  
Table 22  
Terminal  
Compressor Module Normal Terminal Voltages (1 U4 and 1 U5)  
Description  
Normal Terminal Voltages  
for Various Conditions  
Designation of Circuit  
J1-4 to 3  
IPC Communications  
19.2 kbaud serial data, 5 volt signal level.  
or J1-2 to 1  
Refer to Interprocessor Communication Interface.  
J2-2, 1  
J3-7, 6  
Manufacturing Address Use +5 VDC No connection intended.  
Only  
External Circuit Lockout  
Open = 12 VDC: ckt lockout  
Closed 0 VDC: normal  
(ckt. lockout' only if feature is enabled in Service Settings)  
Must be jumpered if this feature is not used.  
J3-4, 3  
Transition Complete  
Not Used  
Open = 12 VDC: pre-transition  
Closed = 0 VDC: transition complete  
(only used with reduced voltage starters)  
J3-2, 1  
J4-5, 4  
Must be jumpered.  
Saturated Condenser  
Refrigerant Temp  
Refer to Temperature Sensor Checkout.  
J4-3, 1  
J5-7, 6  
Entering Oil Temperature  
Refer to Temperature Sensor Checkout.  
Phase A Current  
Transformer Input  
Input for 100-400:0.1 Ratio CT using digital VOM  
in diode test mode open circuit input should read between 1.0 to 1.5  
Volts.  
Refer to Current Transformer Checkout.  
J5-5, 4  
J5-2, 1  
Phase B Current  
Transformer Input  
Same as above.  
Phase C Current  
Transformer Input  
Same as above.  
J6-1 or 2  
to J6-4 or 5  
Input Power  
115 VAC, Refer to Power Supply in Module.  
Power and Miscellaneous I/O.  
E3, E4  
Compressor Motor  
Winding Temp  
Thermostat.  
Internally powered Isolated input.  
Open = 16 Vac: high temp  
Closed = 0 Vac: Ok temp  
E5 to  
High Pressure  
Cutout Input  
Externally powered isolation transformer input,  
2 VA, 115 Vac 115 volts input: normal 0 volts: trip  
J6-4 or 5  
E5, J7-3  
Compressor Contactor  
Output  
Normally open contact, closes for compressor start  
Uses same power input as High Pressure Cutout input above.  
J7-1, E6  
J7-5,6  
Crankcase Heater Output  
Normally closed contact, powers crankcase heater when compressor is  
off.  
Transition Command Output Normally open contact, closes to initiate Wye to Delta Starter transition if  
configured for Reduced Voltage start.  
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Module Power and Miscellaneous I/O  
Table 22  
Terminal  
Compressor Module Normal Terminal Voltages (1 U4 and 1 U5)  
Description  
Normal Terminal Voltages  
for Various Conditions  
Designation of Circuit  
J7-8,9  
Step Load Solenoid  
Normally open contact, closes to energize the Step Load Solenoid Valve.  
J7-1, E7  
Slide Valve Open  
(Load Solenoid) Output  
Triac Output, Refer to Checkout Procedure for MCSP Load/Unload  
Outputs.  
J7-1, E8  
Slide Valve Close  
(Unload Solenoid) Output  
Triac Output, Refer to Checkout Procedure for MCSP Load/Unload  
Outputs.  
J8-1, 3  
J8-1, 4  
J8-1, 5  
J8-1, 6  
J9-6, 5  
Fan Relay 1 Output  
Fan Relay 2 Output  
Fan Relay 3 Output  
Fan Relay 4 Output  
Normally open contact for Variable Speed Fan contactor control.  
Normally open contact for fan contactor(s) control.  
Same as above.  
Same as above.  
Variable Frequency  
Fan Output PWM  
10 Volt Peak, 10 Hz fundamental. Its average value can be read with a DC  
voltmeter. Refer to Section 11 Variable Speed Fan System Trouble-  
shooting.  
J9-4, 3  
J9-2, 1  
Variable Frequency  
Fan Fault Signal  
Fault: 11 V (connector plugged on)  
No Fault: 0 VDC (connector plugged on)  
Refer to Section 11 Variable Speed Fan System Troubleshooting.  
Not Used  
N/A  
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° TP1 +5V  
° TP2 +12V  
J6-1 — 115VAC HOT  
J6-2 — 115VAC HOT  
J6-3 — KEY (N/C)  
J6-4 — NEUTRAL  
J6-5 — NEUTRAL  
IPC (+) —  
IPC (-) —  
IPC (+) —  
IPC (-) —  
J1-4  
J1-3  
J1-2  
J1-1  
E3  
E4  
— COMPRESSOR MOTOR  
— WINDING THERMOST.  
MANUF.  
USE ONLY  
NO CONN. —  
NO CONN. —  
E5  
E6  
J2-2  
J2-1  
— HIGH PRESS SWITCH  
— CRANKCASE HEATER  
LOW PRESSURE SIG.—  
LOCKOUT INPUT —  
KEY (N/C) —  
J3-7  
J3-6  
J3-5  
J7-1 — 115VAC HOT  
J7-2 — KEY (N/C)  
J7-3 — COMPRESSOR CONTCR  
J7-4 — KEY (N/C)  
L
O
W
H
I
G
H
TRANSITION —  
COMPLETE INPUT —  
J3-4  
J3-3  
V
0
L
T
A
G
E
J7-5 — COMPRESSOR  
J7-6 — TRANSITION OUTPUT  
J7-7 — KEY (N/C)  
V
0
L
T
A
G
E
NOT USED —  
J3-2  
J3-1  
SATURATED —  
CONDENSER TEMP —  
J4-5  
J4-4  
J7-8 — STEP LOAD  
J7-9 — SOLENOID VALVE  
ENTERING —  
OIL KEY —  
TEMPERATURE —  
E7  
E8  
J4-3  
J4-2  
J4-1  
— SLIDE VALVE LOAD  
I
N
P
U
T
I
— SLIDE VALVE UNLOAD  
N
P
U
T
PhA —  
COMPRESSOR PhA —  
PHASE PhA —  
CURRENTS PhB —  
KEY (N/C) —  
J5-7  
J5-6  
J5-5  
J5-4  
J5-3  
J5-2  
J5-1  
J8-1 — 115VAC (FANS)  
J8-2 — KEY (N/C)  
J8-3 — FAN RELAY 1  
J8-4 — FAN RELAY 2  
J8-5 — FAN RELAY 3  
J8-6 — FAN RELAY 4  
O
U
T
P
U
T
O
U
T
P
U
T
PhC —  
PhC —  
C —  
CR —  
F —  
FR —  
J9-6  
J9-5  
J9-4  
J9-3  
J9-2  
J9-1  
FAN VARIABLE  
FREQUENCY DRIVE  
NOT USED —  
NOT USED —  
Figure 22 Compressor Module (MCSP) (1U4 and 1U5)  
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Module Power and Miscellaneous I/O  
Interprocessor Communication Bridge Module (IPCB) (1U7)  
The IPCB provides an extension of the IPC link to the Remote Clear Language  
Display. See Figure 23 It prevents “crashes” of the IPC and UCM if the link to  
the RCLD is shorted or misapplied. The IPCB receives and retransmits data to  
and from local to remote links. Therefore the data is available on either link.  
SW1 should be set per the label on the IPCB. LEDs RXA, TXA, RXB and TXB  
should be constantly blinking, synchronously, in normal operation.  
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Figure 23 IPCB Nominal Terminal Voltages  
78  
RLC-SVD03A-EN  
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Module Power and Miscellaneous I/O  
LonTalk® Communications Interface - Chillers Module  
(LCI-C) (1U8)  
The Tracer LCI-C interface acts as a translator between Trane's IPC (Inter-  
Processor Communication) and Echelon's LonTalk® communications protocol  
(ANSI/EIA/CEA 709.1). This allows the chiller to communicate with building  
automation systems which also communicate using the LonTalk® protocol.  
The LonTalk® communications protocol also allows for peer to peer commu-  
nications between controllers so they can share information. Communicated  
setpoints have priority over locally wired inputs to the controller unless the  
controller is set to the "Local" control mode.  
The LCI-C module provides connectivity to Trane's Rover® service tool for  
proper configuration of the LCI-C module.  
Note: LonTalk® communication links are not polarity sensitive.  
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Figure 24 LCI-C Nominal Terminal Voltages  
RLC-SVD03A-EN  
79  
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Variable Speed Fan System  
The purpose of this troubleshooting guide is to help technicians determine if  
the variable speed fan inverter, the compressor module, the variable speed  
fan inverter contactor, the fan motor or the interconnecting wiring is faulty.  
ƽ WARNING  
Hazardous Voltage w/Capacitors!  
Disconnect all electric power, including remote disconnects  
before servicing. Follow proper lockout/tagout procedures to  
ensure the power cannot be inadvertently energized. For variable  
frequency drives or other energy storing components provided by  
Trane or others, refer to the appropriate manufacturer’s literature  
for allowable waiting periods for discharge of capacitors. Verify  
with an appropriate voltmeter that all capacitors have discharged.  
Failure to disconnect power and discharge capacitors before  
servicing could result in death or serious injury.  
Note: For additional information regarding the safe discharge of  
capacitors, see PROD-SVB06A-EN or PROD-SVB06A-FR  
In this troubleshooting procedure, the components will be referred to by the  
descriptions below:  
Description  
Circuit 1  
1U4  
Circuit 2  
1U5  
Compressor Module  
Variable Speed Fan Motor  
Variable Speed Fan Inverter  
3B2  
4B2  
6U9  
6U10  
1K13  
Variable Speed Fan Inverter Contactor 1K9  
Variable Speed Fan Inverter Fuses  
1F18 - 1F20 1F21 - 1F23  
Inverter Diagnostics  
The Inverter has two LEDs for diagnostic purposes. They are:  
Power On LED: This green LED is illuminated any time that more than 50  
VDC is present on the DC Bus Capacitors. Typically when power is removed  
from the TRANE AC INVERTER this LED will remain illuminated for up to 60  
seconds while the DC Bus Capacitor Voltage discharges. This LED also  
indicates that the 5 VDC Supply Voltage on the TRANE AC INVERTER control  
board is present.  
Alarm LED: When this red LED is illuminated constantly, it indicates that the  
motor is overloaded and the drive is about to fault on a motor overload. When  
the Alarm LED is flashing, it indicates the drive is faulted. By counting the  
number of times the Alarm LED flashes, the cause of the fault can be deter-  
mined. The following table lists the possible fault conditions for the TRANE  
AC INVERTERS and the number of times the Alarm LED will flash:  
Fault Condition  
Number of Alarm LED flashes  
1
Bus Overcurrent Fault  
80  
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Variable Speed Fan System  
Bus Overvoltage Fault  
Motor Overload Fault  
Low Bus Voltage Fault  
PWM Generator Fault  
Logic Fault  
2
3
4
5
6
7
Stalled Motor Fault  
Fault Descriptions  
Bus Overcurrent Fault: DC Bus Current exceeds the drive rated peak  
current.  
Bus Overvoltage Fault: DC Bus Voltage exceeds 400 VDC on 200/230 VAC  
input units or exceeds 800 VDC on 400/460 VAC input units.  
Motor Overlad Fault: The drive operated in current limit (110 % of rated  
current) for a period of 60 consecutive seconds. If the motor current reduces  
to less than 110 % and the motor reaches commanded speed the overload  
timer will begin to count down.  
Low Bus Voltage Fault: DC Bus Voltage is less than 200 VDC on a 200/230  
VAC input unit or is less than 400 VDC on a 400/460 VAC input unit. If the  
motor is already running, this fault will not occur. Instead, the motor speed  
will be reduced to a speed that the proper voltage can be applied to the  
motor.  
PWM Generator Fault: The drive failed to switch a PWM output properly.  
Logic Fault: The Microcontroller in the drive executed an illegal instruction.  
Stalled Motor Fault: Motor failed to accelerate to ½ the motor speed setpoint  
in 30 seconds.  
Automatic Restart: If the drive should fault, the drive will automatically  
attempt one restart after a delay of 5 seconds. If the drive faults a second  
time, the drive will not attempt to restart and the fault must be cleared before  
the drive will run again.  
Fault Clearing:  
Drive Faults may be cleared by one of the following methods:  
Removing and reapplying power to the controller.  
Setting the speed control input duty cycle to less than 7% for 1 second.  
RLC-SVD03A-EN  
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Variable Speed Fan System  
Troubleshooting Procedure  
ƽ WARNING  
Live Electrical Components!  
During installation, testing, servicing and troubleshooting of this  
product, it may be necessary to work with live electrical  
components. Have a qualified licensed electrician or other  
individual who has been properly trained in handling live  
electrical components perform these tasks. Failure to follow all  
electrical safety precautions when exposed to live electrical  
components could result in death or serious injury.  
1. Go into the "Machine Configuration Menu" by performing the following  
keystrokes: Service Settings, Previous, +, -, +, -, +, -, Enter. Check this  
menu to be sure that "Fan Control" and "Variable Speed Fan" are Enabled  
for both circuits. The "Fan Control" menu item was replaced with "Unit  
Type" on units built after September 1, 1994 (SN U94HXXXXX and later).  
Set "Unit Type" to RTA or RTU, which-ever applies. Be sure that "Variable  
Speed Fan" is Enabled for both circuits.  
2. Verify that all inverter power and control signal wiring is correct for the  
affected circuit, using Figure 11-1 and Trane wiring diagram 2307-3328.  
The wiring diagram is found in the Unit Wiring Section of RTAA-IOM-4 or  
on the inside of the unit control panel door.  
3. Attempt to start the compressor on the affected circuit. Twenty-five or  
thirty seconds prior to compressor start, the variable speed fan inverter  
contactor is energized. Be sure that this is heard. If not heard, attach an  
AC voltmeter from pin J8-3 to ground on the compressor module. Reset  
the control and look for a 115 volts reading on the voltmeter at pin J8-3,  
25 to 30 seconds prior to compressor start. If this voltage is read but the  
contactor does not pull in, check for an open circuit in the contactor coil or  
an open circuit in the interconnecting wiring to the contactor.  
4. Check the fan motor by completely bypassing the inverter. Disconnect  
power from the unit and remove the three-phase power wiring from the  
inverter. Connect it to the three-phase power wiring of the fan motor,  
using splice wires with 1/4 inch male quick connects on both ends. Re-  
apply power to the unit and reset the circuit being tested. Twenty-five or  
thirty seconds before the compressor starts, the contactor that would  
normally apply power to the inverter should pull in and the fan should run.  
If the fan does not run, check the line fuses and contactor contacts.  
5. Disconnect power from the unit and reconnect the inverter module. At  
the same time, check for damaged wiring or loose quick connects on the  
inverter.  
6. Re-apply power to the chiller and check the compressor module power  
supply, by reading the DC voltage levels from TP1 to the circuit board  
edge ground and from TP2 to the circuit board edge ground. TP1 and TP2  
are found on the upper lefthand side of the compressor module. The volt-  
age at TP1 should be +5 .25 VDC. The voltage at TP2 should be +12  
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Variable Speed Fan System  
.6 VDC. If there is no voltage at either of these two test points, check the  
incoming 115 VAC between pins J6-1 (hot) and J6-5 (neutral) and check  
fuse F1, mounted on the upper right-hand corner of the circuit board. If  
the fuse is OK and the voltage between J6-1 and J6-5 is 115 VDC, but the  
TP1 and TP2 voltages are out of range, replace the compressor module.  
Figure 25  
Variable Speed Fan Inverter  
7. Remove connector P9 or P10 (whichever applies) from the inverter and  
place a jumper wire between terminals F and FR on the female connec-  
tor. See Figure 11-1 for the location of these wires. This will prevent the  
control from reporting a fault diagnostic. Restart the unit and carefully  
measure the DC voltage between wires C (+) and CR ( - ) on the same  
female connector. The voltage should be 2 to 10 VDC when the compres-  
sor on the affected circuit is running. At compressor start, this voltage  
will start at approximately 2 VDC and gradually ramp up to about 10 VDC.  
This voltage level is directly proportional to fan speed. At 5 VDC, the fan  
should be running at 50% of full speed and at 7 VDC the fan should be  
running at 70% of full speed.  
NOTE: The output from the compressor module is a pulse width modulated  
signal, 10 volt peak and 10 Hz. fundamental. It's average value can be read  
with a DC voltmeter.  
8. Remove the jumper wire and reconnect connector P9 or P10. While the  
inverter is still powered, measure the DC voltage between pins J9-4 (+)  
and J9-3 ( - ) on the compressor module. The connector must be plugged  
RLC-SVD03A-EN  
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Variable Speed Fan System  
on at both ends while measuring this voltage. If the reading is between  
11.5 and 12.5 VDC, two problems may exist:  
The inverter indicates that it has a fault by opening a semiconductor  
switch within the inverter. The inverter will send a fault signal to the UCM  
when:  
It has gone through a self-shutdown. One cause of this could be  
high line voltage. A 10% high line voltage could cause a diagnos-  
tic trip.  
The output frequency of the inverter is being internally limited to  
a less than 50% of the signal speed commanded by the UCM.  
Excessive fan motor current, high temperature or internal inverter  
failures could cause this to occur.  
There is an open circuit in the fault signal wiring, somewhere between  
the inverter and the compressor module.  
If the reading is 2 VDC or less between pins J9-4 and J9-3, an inverter fault  
diagnostic for the affected circuit should not be displayed. But if the variable  
speed fan in still not working, check these two interconnecting wires from  
the compressor module to the inverter, to be sure they are not shorted. The  
inverter cannot send the compressor module a fault signal if these two wires  
are shorted together.  
9. If all settings and voltages through Step 8 are acceptable and the fan  
does not operate, replace the variable speed fan inverter.  
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Other Service Features  
Service Pumpdown  
The UCM provides for a "onetime" Service Pumpdown mode, in which a  
service-technician can direct a particular compressor to start and run for one  
minute, to accomplish pumpdown of the low side of the refrigeration system  
(evaporator and EXV).  
To aid in accomplishing this pumpdown, certain noncritical diagnostics will be  
ignored or disabled during this mode. Critical diagnostics such as those  
associated with motor protection, high pressure, and chilled water flow, will  
still be' enforced and may prevent or terminate the sequence.  
Service Pumpdown Procedure  
1. Place the Chiller in the Stop Mode using the Stop Button on the CLD and  
allow the Chiller, if currently running, to go through its shutdown  
sequence.  
2. Manually close the liquid line shutoff valve on the circuit to be pumped  
down.  
3. Use the CPM's Operator Interface to begin the mode specifically for the  
compressor/circuit you wish to pumpdown by selecting and "Enabling" it  
in the Service Tests Group. The CLD will then be displaying an Operating  
Code for Service.  
4. The UCM shall then begin the start sequence (without restart inhibit) and  
turn on the selected compressor once the EXV has opened to its pre-  
position. The compressor shall run for a period of 1 minute at its mini-  
mum load and the condenser fans will stage under normal fan control.  
The UCM will automatically shut off the compressor and condenser fans,  
close the EXV, and return the chiller to the normal stop mode once the 1  
minute timer has expired. The pumpdown sequence cannot be repeated  
again without a UCM power down reset.  
NOTE: The unload solenoid is always kept energized for approximately 1  
hour after any compressor shutdown and the oil sump heater is continuously  
energized.  
5. Manually close the discharge line shutoff valve and the oil line shutoff  
valve.  
6. Remove all power to the chiller and service as required.  
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Other Service Features  
ƽ WARNING  
Hazardous Voltage w/Capacitors!  
Disconnect all electric power, including remote disconnects  
before servicing. Follow proper lockout/tagout procedures to  
ensure the power cannot be inadvertently energized. For variable  
frequency drives or other energy storing components provided by  
Trane or others, refer to the appropriate manufacturer’s literature  
for allowable waiting periods for discharge of capacitors. Verify  
with an appropriate voltmeter that all capacitors have discharged.  
Failure to disconnect power and discharge capacitors before  
servicing could result in death or serious injury.  
Note: For additional information regarding the safe discharge of  
capacitors, see PROD-SVB06A-EN or PROD-SVB06A-FR  
NOTE: If it is necessary to service the circuit/ compressor while allowing  
the opposite circuit to start and run, first temporarily disconnect all power to  
the chiller and then disconnect all control power connections to the  
compressor and associated controls, by pulling off all the control power  
voltage connectors on the right hand side of the associated MCSP module.  
Control power to the associated contactor should also be disconnected, as  
should the power lead(s) to the high pressure switch at the control power  
terminal block. Repower the chiller, and lockout the circuit you are servicing  
by entering the Service Tests Menu and enabling CIRCUIT LOCKOUT for the  
desired circuit. Placing the chiller switch into the Auto mode will then allow  
the opposite circuit to run.  
7. Return all valves to their normal position. temporarily remove all power  
and reconnect all wiring when servicing is completed.  
8. Reset the chiller to clear diagnostics (and diagnostic history if desired) to  
resume normal operation.  
COMPRESSOR TEST  
The UCM provides for a Compressor Test feature which is designed to allow a  
service-technician to direct a particular compressor to be the next  
compressor to stage on, run and modulate. This allows the temporary  
override of the lead/lag sequencing currently in effect and relieves the  
technician from forcing staging of compressors thru load or setpoint changes.  
It is important to note that invoking this feature does not put the chiller into  
any kind of override "mode" and no action is required to return to "normal  
operation". The chiller will continue to run normally and the current lead/lag  
sequence will again be in effect, once the selected compressor has started.  
This feature is used in the Slide Valve Checkout Procedure detailed in Slide  
Valve Checkout Procedure.  
Invoking Compressor Test  
1. With the Chiller in the Auto Mode, regardless of whether or not other  
compressors are currently running, use the CLD to enter the Service  
Tests Menu and enable the COMPRESSOR TEST for the appropriate  
compressor. The selected compressor will automatically stage on, once  
the anti-recycle or restart inhibit timer is satisfied and the EXV is preposi-  
86  
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Other Service Features  
tioned (if not already controlling). Most often the stage-on will be accom-  
panied by a controlled stage-off of an already running compressor. Since  
normal operation is in effect, a constant load or setpoint change may be  
required to keep the compressor from staging off later.  
Circuit Lockout  
The UCM provides for a circuit lockout feature which prevents the  
compressor(s) of the selected refrigeration circuit(s) from starting or- running.  
If currently running, the compressor(s) and circuit will go through a controlled  
shutdown. This lockout can be initiated with either an external hardware  
interlock on either MCSP of a given circuit or can be invoked through the CLD.  
Invoking Circuit Lockout  
To invoke circuit lockout manually, simply enter the Service Tests Menu and  
move to the CIRCUIT LOCKOUT display, and "enable" the circuit lockout for  
the appropriate circuit. Circuit Lockout can then be verified in the Chiller  
Report under "Circuits Locked Out". The circuit will remain locked out until  
manually "disabled" at the same place in the menu.  
To use an external hardwired interlock to accomplish lockout, refer to the IOM  
or system wiring diagrams for the field installed interlock connections. The  
external interlock feature must also be "enabled" in the Service Settings  
Menu. (Open = normal, and closed = locked out).  
Circuit Diagnostic Reset  
The UCM provides for a Circuit Diagnostic Reset feature which unlike the  
Chiller Reset, does not require a complete chiller shutdown to clear CMR  
diagnostics. By using this feature it is possible to service and restart a circuit  
that has been latched out on a circuit diagnostic while allowing the alternate  
circuit to remain on-line making chilled water.  
Invoking Circuit Diagnostic Reset  
Using the CLD, enter the Diagnostic Menu, and "enable" circuit reset on the  
appropriate circuit. This will clear all latching diagnostics for that circuit (but  
will not remove them from the historical list. Clearing the History list can be  
accomplished when compressors are running, by entering the Diagnostic  
Menu and scrolling to the CLEAR DIAGNOSTIC HISTORY display). Press  
Enter to clear the historical diagnostics.  
RLC-SVD03A-EN  
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Literature Order Number  
File Number  
RLC-SVD03A-EN  
SV-RF-RLC-SVD03A-EN-0805  
RTAA-SB-9  
Trane  
Supersedes  
A business of American Standard Companies  
Stocking Location  
Inland  
Trane has a policy of continuous product data and product improvement and reserves  
the right to change design and specifications without notice. Only qualified  
technicians should perform the installation and servicing of equipment referred to in  
this bulletin.  
For more information contact your local district  
office or e-mail us at [email protected]  
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