Electric Motor Megger Test

Deviations from rated fla could signify problems with the motor under test.

Electric motor megger test.

Curve b shows same values corrected to 20 c see page 22 giving a definite downward trend toward an unsafe condition. Baker instruments is a leading provider of test equipment for the electrical condition monitoring of motors generators and coils. Figure 3 typical scale on the megger insulation tester. Minimum test value for a good electric motor is at least 1mω running amps test with the motor running check the full load amps fla with a suitable meter or preferably a clamp on meter and compare with the motor name plate fla.

Insulation resistance quality of an electrical system degrades with time environment condition i e. Megger makes electrical test equipment to help you install improve efficiency and extend the life of electrical assets and cable networks at high medium and low voltage. When it comes to checking out electric motors there are special measuring instruments that may be used to detect and diagnose malfunctions. Check c to e s to e r to e.

Figure 4 typical record of insulation resistance of a mill motor. The ideal mode of testing is phase to phase and phase to ground. You can test your motor insulation with the help of a megger. Place one megger probe to the any mounting bolt on the breaker box to test for grounding continuity then touch the other probe to a motor terminal.

Reverse side of card at right is used to record the test data. Curve a shows test values as measured. Insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail. If you want to test a 480v motor then the voltage required would be 1000v with a reading of 2m ohms or more.

The megger test is a method of testing making use of an insulation tester resistance meter that will help to verify the condition of electrical insulation. For a three phase motor insulation resistance is usually measured between each motor winding or phase and between each motor phase and motor frame earth using an insulation tester or megger. Temperature humidity moisture and dust particles. Step 3 crank the handle for about a minute and notice the resistance reading.