Testing motor coil resistance

A three-phase induction motor has internal coil windings.

These windings must remain the correct value for the motor size and coil configuration, and they must remain the same value as one another.

Typical values are six ohms between all phases.

In a typical three phase induction motor circuit, an appropriate place to test is at the load side of the direct-on-line motor starter.

Figure 1

      O  O  O
       /  /  /
      /  /  /
      O  O  O
      A  B  C

Tests should be made between A and B, A and C, and B and C.