Motor Insulation Resistance Test

Ground insulation test of a motor.

Motor insulation resistance test.

Whether the dielectric is good or bad. After the required connections are made you apply the test voltage for a period of one min. 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. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms.

The measurement of insulation resistance is carried out by means of a megohmmeter high resistance range ohmmeter this is how the test works. Insulation resistance decreases in temperature or moisture. Basically there are three different tests that can be done using a megohmmeter. Because electrical insulation will exhibit dynamic behavior during the course of your test.

When performing insulation resistance testing you must maintain consistency. After 1 min you should read and record the resistance value. Set the voltage. Dc voltage of 500 or 1000 v is applied between the windings and the ground of the motor.

Loss of insulation resistance of an electric motor is one of the first signs of motor failure. Insulation resistance test insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail. Using insulation testing with an instrument such as the fluke 1555 10 kv insulation tester combined with fluke connect technology such leaks can be detected as insulation resistance slowly tapers over time a sign of normal and expected deterioration. 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 insulation keeps the current flowing along the wire exactly as intended. 1 insulation resistance ir this is the simplest of the tests. 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.