Motor so the insulation resistance has returned to a higher value and has remained stable over time indicating a good conition.
Motor insulation resistance test procedure pdf.
The measurement of insulation resistance is carried out by means of a megohmmeter high resistance range ohmmeter this is how the test works.
Curve indicates a e potential problem.
Loss of insulation resistance of an electric motor is one of the first signs of motor failure.
Insulation resistance testing is a non destructive test procedure.
At c the insulation resistance value after the motor has been rewound.
During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched.
When performing insulation resistance testing you must maintain consistency.
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.
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.
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.
Regular checks of motor insulation resistance the key to prolonging the life of any electrical device is periodic checks maintenance the insulation resistance of stored and active motors should be checked regularly.
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.
Ground insulation test of a motor.
Insulation resistance decreases in temperature or moisture.
Larger insulation systems will show a steady decrease.
It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs.
After 1 min you should read and record the resistance value.
Insulation resistance test insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail.
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.
Smaller systems will remain steady because the capacitive and absorption currents drop to zero faster than on larger systems.
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.
The test should also be performed after a motor is.
Set the voltage.
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.
The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms.
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.
