Testing a 3-phase motor is as simple as holding the leads of a volt ohmmeter. The trick is knowing which leads to hold on to and which wires make no difference at all. Once you have tested a few 3-phase motors, the process will come easily.
step 1
Unscrew the motor's wire cover box from the motor after turning off all power that feeds that electric motor. Mark all the pairs of wires from the motor to the power feed so rotation will remain the same after checking the motor.

step 2
Remove any wire nuts or tape that are insulating the connections. You must have bare copper wires for testing the motor leads.

step 3
Switch the volt ohmmeter to ohms and place the leads from the motor case to each motor power connection lead one at time. Each reading should be infinite ohms, or OL, on the meter. If the meter does not read OL, you may have a direct short in the motor windings. Replace the motor.