Electric Motor Winding Resistance Test

With the motor running check the running amps of the motor using.

Electric motor winding resistance test.

An electrical induction motor contains windings or wire wrapped around a cylindrical shaft. Insulation resistance is usually measured between motor windings and earth using an insulation tester or megometer. Insulation resistance of motor winding using insulation tester meter set to the 500 volt scale 1000v dc verify from phase to phase u to v v to w w to u and. The most common failure mode of a 3 phase ac motor is burnt winding or shorted winding leading to the damage of the motor.

Insulation resistance test insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail. Consult the motor schematic or a diagram of the motor s windings and use the meter to measure the resistance of the windings. An overview of two basic winding resistance tests one can perform in the shop. How to check the motor winding resistance by william hirsch updated march 16 2018.

Each winding leg should have some small resistance reading. Minimum test value of the electric motor is 1 meg ohm 1 mω. Loss of insulation resistance of an electric motor is one of the first signs of motor failure. Check from phase to earthing u to e v to e w to e.

When an electric motor is broken one suspect is the fiel coild of the motor stator. 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. You may find that when it runs ungrounded that the casing becomes live at up to supply voltage. A number of standards provide maximum deviation percentages but typical limits are 1 to 3 between the mean average for the three windings.

Winding resistance test results are compared between the three phases on a 3 phase motor. The meter should not show an open or a short when a winding leg is measured. Often it is required to test the winding of the 3 phase windings with the aid of a multimeter or ohmmeter to determine whether the motor is still good or burnt or shorted. With a multimeter set to low ohms usually 200 test between each winding terminal and the metal casing of the motor.

When an electric current flows though the wire a magnetic field is induced inside the coil of wire. In this video we show different tests balancing test continuity coil.