Electric Motor Winding Testing

Since there are three terminals.

Electric motor winding testing.

If there is any reading on any of these then the motor is bad do not use it. Ac motor winding resistance test. You may find that when it runs ungrounded that the casing becomes live at up to supply voltage. If the winding s insulation wears away near the motor s case the bare wire winding shorts to ground.

Record initial and corrected values on motor testing record sheet. For phase to phase terminals u to v v to w w to u test the motor winding resistance or ohm reading using a multimeter or ohmmeter. Bearing problems may be the number one cause of electric motor failure but electrical faults are a close second. Check that the correct voltage is applied to the motor.

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

Usace testing procedure cont 11 winding dc resistance test follow usace procedure three sets of results total a to b phase b to c phase c to a phase correct values to 40 c using the formula in step 8. Ac motor winding resistance test check the motor winding resistance or ohms reading with a multimeter. Technicians should perform a series of tests on an electric motor during routine preventive maintenance or before replacing it. This includes testing the motor for grounded windings.

The reading ohms for each winding should be the same or almost identical. With a multimeter set to low ohms usually 200 test between each winding terminal and the metal casing of the motor. To check the condition of the armature windings the armature will probably have to be removed from 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.

All values obtained from winding dc resistance test. Know that the three steps have identical or almost identical windings. Most repair shops will use a megger or a ground insulation tester. However while the meg ohm test has a valid role to play it is simply not capable of detecting all the likely faults within a motor s winding.