Electric Motor Megger Test

Insulation resistance quality of an electrical system degrades with time environment condition i e.

Electric motor megger test. You can test your motor insulation with the help of a megger. Reverse side of card at right is used to record the test data. The insulation resistance tester generally known by its trade name megger is capable of providing critical information regarding the condition of motor insulation. Step 3 crank the handle for about a minute and notice the resistance reading.

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. Temperature humidity moisture and dust particles. Baker instruments is a leading provider of test equipment for the electrical condition monitoring of motors generators and coils. Whether you are testing in a motor repair shop in an industrial plant on a ship or up a wind turbine baker instruments motor test equipment allows you to fully understand the condition of the motor the power supply and the load.

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

Insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail. Figure 3 typical scale on the megger insulation tester. 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.

If you want to test a 480v motor then the voltage required would be 1000v with a reading of 2m ohms or more. Curve a shows test values as measured. Curve b shows same values corrected to 20 c see page 22 giving a definite downward trend toward an unsafe condition. 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.