Motor Insulation Resistance Test Procedure Pdf

The test should also be performed after a motor is.

Motor insulation resistance test procedure pdf.

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. Smaller systems will remain steady because the capacitive and absorption currents drop to zero faster than on larger systems. A if the insulation resistance of a new cleaned or repaired motor that has been stored for some time is less then 10 mω the reason might be that the windings are humid and. Insulation resistance test insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail.

Insulation resistance testing purpose. A spot test should be performed at reg ular intervals every six months for ex ample to track the changes in insulation integrity. During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched. Dc voltage of 500 or 1000 v is applied between the windings and the ground of the motor.

Curve d indicates a good insulation with an excellent polarization index of 5. Ground insulation test of a motor. The test measures the insu lation resistance between the phases and or between phase and ground. Loss of insulation resistance of an electric motor is one of the first signs of motor failure.

Aemc instruments testing methods based on the influence of the test voltage application time pi dar these methods involve measuring successive insulation resistance values at specified times. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. At c the insulation resistance value after the motor has been rewound. An insulation spot test is an insulation resistance test that can be used to verify the condition of the insulation over the life of the motor.

Motor so the insulation resistance has returned to a higher value and has remained stable over time indicating a good conition. With a little record keeping and common sense however you can get a good picture of the insulation condition from values that are only relative. Insulation resistance testing is a non destructive test procedure. Curve indicates a e potential problem.

For a three phase motor the isolation resistance can usually be measured between each motor winding or phase and between each motor stage and motor frame earth by an insulation tester or megger 4. When performing insulation resistance testing you must maintain consistency. 1000 100 10 1 12 3 4 56 7 89 10 time in minutes reading in megohms d e figure 2 absorption curve of test conducted on 350 hp motor. Insulation resistance decreases in temperature or moisture.

After 1 min you should read and record the resistance value. Larger insulation systems will show a steady decrease. Set the voltage.