THREE-PHASE COMPRESSOR MOTOR WINDING-TO-WINDING RESISTANCE MEASUREMENT PROCEDURE
|14. Check a three-phase compressor motor for winding-to-winding shorts or|
partially shorted windings as follows:
Because of the extremely low resistance values being measured, an accurate
VOM/DMM must be used to perform this step, otherwise a good compressor
may be judged as bad. Connect the VOM/DMM across the leads connected to
the compressor terminals T1 and T2, then measure and record the resistance
as shown in Figure SP-9-18.
Repeat the resistance measurements between the leads connected to
compressor terminals T2 to T3 and T3 to T1.
|VOM/DMM indicates a measurable resistance across each winding. As a rule of
thumb, the motor windings are usually judged to be good if the resistance
measured across each winding is nearly identical to that of the other two
Assume that the resistances measured across the three windings are 5 ohms, 4.99
ohms, and 5. J ohms. In this example, the motor windings would be judged to be
good because the three motor resistances are nearly identical.
Assume that the resistance measured across the three windings are 5 ohms, 4.99
ohms, and 3.0 ohms. In this example, the motor windings would be judged to be
partially shorted because one of the resistances (3.0 ohms) is significantly
different than the other two.
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