Ground Fault Troubleshooting; Check Purge Compressor Operation - Carrier 19DV Series Installation, Operation And Maintenance Instructions

enclosure if this has occurred. If metal particulate has fallen into the rectifier or inverter assemblies
contact Service Engineering or your Technical Service Manager for further instructions.
WARNING: Do not apply power unless a qualified Carrier technician is present. Serious personal injury may result.

5.3 Ground Fault Troubleshooting

Follow this procedure only if ground faults are declared by the chiller controls. Test the chiller compressor motor
and its power lead insulation resistance with a 500-v insulation tester such as a megohmmeter.
1. Open the VFD main disconnect switch and follow lockout/ tagout rules.
CAUTION: The motor leads must be disconnected from the VFD before an insulation test is performed. The voltage
generated from the tester can damage the VFD.
2. With the tester connected to the motor leads, take 10-second and 60-second megohm readings as follows: Tie
terminals 1, 2, and 3 together and test between the group and ground.
3. Divide the 60-second resistance reading by the 10-second reading. The ratio, or polarization index, must be one
or higher. Both the 10 and 60-second readings must be at least 50 megohms.
If the readings are unsatisfactory, repeat the test at the motor with the power leads disconnected. Satisfactory
readings in this second test indicate the fault is in the power leads.

5.4 Check Purge Compressor Operation

Enter Quick Test menu (under Main Menu), select "Quick Test Purge Comp." Connect a pressure gauge to purge
compressor inlet Schrader valve (suction is top fitting). The purge system is shown in Fig. 10. The reading should
be about 62.1+/- 6.9 kPa. If not, please adjust the purge expansion valve in the R-134a purge compressor circuit
until the reading is correct.
NOTE: This step should only be performed if the purge is not working correctly. The installation of the gage will
result in a loss of refrigerant and the charge of R-134a is a very small quantity affecting the operation of the purge.
The charge should be weighed into this circuit using a charging cylinder or similar device.
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