नेपालमा जातजाति

How to Test the Winding of a 3 phase Motor

To determine whether a 3 phase motor is still good or has gone bad, a simple ohmmeter test across the windings of the motor will reveal its true state of health. As shown below, the indicated terminal matrix (blue lines) shows the way the windings of a 3 phase motor should be tested with an Ohmmeter
The first thing to do before testing the windings of the motor is to remove the links linking terminals W2U2V2 and the disconnect the motor from supply (L1, L2, L3). A multimeter terminals placed across this matrix of terminals will indicate the following readings for a good 3 phase motor:
(a) Terminals W1W2, U1U2, V1V2 will indicate continuity for a good motor
(b) Every other terminal combinations should indicate Open for a good motor
(c) Readings between any of the six (6) terminals and the motor frame signifying earth   
    (E) should indicate open for a good motor.

Ohmmeter Readings for a Bad 3 phase Motor
In the case of a burnt or bad 3 phase motor, this matrix of terminals should indicate  the opposite readings for a bad motor:
(a) If any of the terminal combinations W1W2, U1U2, V1V2 should indicate open then
     the motor is bad.
(b) If any other terminal combinations should indicate continuity instead of open, then           
     the motor is bad.
(c) If the reading between any of the six (6) terminals and motor frame (E) should 
     indicate continuity, then the motor is dead.