Electric Motor Winding Tester

Set your multimeter to ohms.

Electric motor winding tester.

Test electric motor windings when a bad motor winding cannot be found by a physical inspection many times an ohmmeter may show that there is a defective winding. Bearing problems may be the number one cause of electric motor failure but electrical faults are a close second. Remember that the three phases have identical windings or. Set the voltage level of the insulation resistance tester to 500v.

Technicians should perform a series of tests on an electric motor during routine preventive maintenance or before replacing it. To check the condition of the armature windings the armature will probably have to be removed from the motor. Ac motor winding resistance test check the motor winding resistance or ohms reading using a multimeter or ohmmeter for phase to phase terminal u to v v to w w to u the ohms reading for each winding must be the same or nearly the same. This should allow you to isolate your problem.

With a multimeter set to low ohms usually 200 test between each winding terminal and the metal casing of the motor. We ll start with a quick review of why testing is important followed by a discussion of rotor bar hipot surge and motor winding resistance as well as a discussion of vibration analysis. The measurement of insulation resistance is carried out by means of a megohmmeter high resistance range ohmmeter this is how the test works. Test t1 to t2 t2 to t3 and t1 to t3.

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. The megger will help to detect areas of deteriorating insulation where the windings may soon short. The most common failure mode of a 3 phase ac motor is burnt winding or shorted winding leading to the damage of the motor. U v w is a european winding designation.

During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched. If there is any reading on any of these then the motor is bad do not use it. 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. Dc voltage of 500 or 1000 v is applied between the windings and the ground of the motor.

Most repair shops will use a megger or a ground insulation tester. This includes testing the motor for grounded windings. Ground insulation test of a motor. While testing make sure the leads on each end are not touching other leads or anything else.

If the winding s insulation wears away near the motor s case the bare wire winding shorts to ground.