How Do You Test Electric Motor Windings

The most common failure mode of a 3 phase ac motor is burnt winding or shorted winding leading to the damage of the motor.

How do you test electric motor windings.

Keep the multi meter set for 30 000 ohms and touch one test lead to one terminal and the other to another terminal. Since there are three terminals. Small universal motors as for portable electric drills may. For proper motor operation all windings must have megohm readings to ground i e.

To the motor enclosure. Ac motor winding resistance test check the motor winding resistance or ohms reading with a multimeter. 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. Armature test 1 to check the condition of the armature windings the armature will probably have to be removed from the motor.

If there is any reading on any of these then the motor is bad do not use it. Most repair shops will use a megger or a ground insulation tester. Dc voltage of 500 or 1000 v is applied between the windings and the ground of the motor. Sounds like you have a winding down to ground.

If windings are shorted together the electro magnetic fields cannot be created for that coil causing the motor to run erratically or fail all together. Each of the sets of windings should read about the same ohms value. During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched. If you think you may have bad spindle motor windings it s important to know for sure.

Here is a basic breakdown on how to check motor windings with a multimeter keep in mind this is just a quick way to determine if your motor is in need of further. With a multimeter set to low ohms usually 200 test between each winding terminal and the metal casing of the motor. Power supply test for single phase motors the expected voltage is about 230v or 208v depending whether you are using the uk or america voltage system. The measurement of insulation resistance is carried out by means of a megohmmeter high resistance range ohmmeter this is how the test works.

If you have access to a multimeter it s easy to determine if you have an immediate problem. 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. Test for direct shorts in the motor s power windings in induction non brush type motors. If a winding is grounded out the winding insulation is broken down or the armature is touching the stator unless there is a possibility of a loose or chafing wire inside.

The megger will help to detect areas of deteriorating insulation where the windings may soon short.