Trane RTHD

28 RLC-SVD05A-EN
Current Transformers
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 starting compressor
can be determined in TechView. The mode will change from stopped to
starting. This can also been seen on the DynaView under the Modes tab. Note
the diagnostic(s) that results, then place the Chiller into the “Stop” mode.
3 For the next portion of the procedure, pull the unit's disconnect and interrupt
all high voltage power to the control panel. Locate the toroid (doughnut)
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.
4 Utilizing the Schematic Wiring Diagram, locate the termination of the
transformer's wiring into the Phoenix plug at the appropriate Starter module
at pin header J7. Pull off the appropriate Phoenix connector from the pin
header on the Starter.
CAUTION
Equipment
Damage!
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 Starter input. Take care to properly reconnect the CT's Phoenix
connector prior to attempted start of the compressors.
5 Using a digital volt-ohmmeter, measure the resistance of the transformer(s)
by probing the appropriate pair(s) of receptacles within the Phoenix
connector. The receptacle pairs of the Phoenix connector are most easily
measured by using meter leads with pointed probes and contacting the
exposed metal of the connector through the top Phoenix connector.
6 Refer to Tab l e 5 which lists the normal resistance range for each extension of
current transformer. Check the measured resistance against the value listed
per transformer extension. If the resistance is within tolerance, the
transformer and Phoenix connector can be considered good. Go on to step 8.
67-100 X13580269-01 100 66.67-100 23.5
100-150 X13580269-02 150 100-150 35.0
134-200 X13580269-03 200 134-200 46.0
184-275 X13580269-04 275 184-275 67.0
267-400 X13580269-05 400 267-400 68.0
334-500 X13580269-06 500 334-500 89.0
467-700 X13580269-07 700 467-700 128.0
667-1000 X13580269-08 1000 667-1000 235.0
33.4-50 X13580269-09 50 33.37-50 11.5
50-75 X13580269-10 75 50-75 17.0
Table 5. Current Transformers Rating and Resistance
Unit RLA Part Number
Rating
(amps)
Usable Range
(amps)
Resistance Ohms
(+10%)