Megging the motor
Proceed in accordance with the type of starter.
Mechanical starter
Open the main disconnect switch and the compressor motor starter and meg the motor as follows:
1. Using a megohm meter (megger), meg between phases and each phase to ground. See
Figure 15. Interpret the readings using the graph in Figure 14.
2. If the readings fall below the shaded area, remove the external leads from the motor and
repeat the test.
Note: The motor is to be megged with the starter at ambient temperature, after 24
hours of idle standby.
Figure 15: Megging the motor windings - mechanical starter
VFD powered or solid state soft starter
Meg the motor as follows:
1. Disconnect the power leads from the VFD or solid state starter to the motor. This is required
so that only the motor is subjected to the applied voltage from the megger tester.
2. Using a megohm meter (megger), meg between phases and each phase to ground. See
Figure 16. Interpret these readings using the graph of Figure 14.
Figure 16: Megging the motor windings - VFD or solid state soft starter
41Model YK (Style H), R-134a and R-513A
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