To Megger test a DC motor, you might need more than a simple ohmmeter because the problem you are investigating may not become clear until the motor is in operation. A viable solution is to Megger test with high-voltage test equipment using 1,000 – 10,000. With this test equipment, you can identify insulation leakage in motor coils and related wiring.
The Megger test procedure is relatively simple. First, to protect yourself, be sure the motor rests on an insulated pad. Then disconnect power from the motor and the electrical terminations from the power source feeding the motor. Connect one of the motor leads to the Megger probe and the other lead from the Megger test equipment to the motor’s metal frame. Turn on the Megger test unit. It will take a couple of seconds for the Megger test unit to display the voltage. (A lower ohm reading indicates deterioration in the wiring insulation.) Now turn off the test equipment, rotate the end shaft about 30 degrees and repeat the test.
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