How Do You Test An Electric Motor

Check the multimeter measurement.

How do you test an electric motor.

Since the motor is turning freely it won t do any good to lubricate the bearings and since the capacitor checks out and the motor is humming it means you ve got voltage to the terminals. Electric motors have had a reputation for being a mix of science and magic. Knowledge of the basics together with powerful new test equipment vastly simplifies the job. Ac motor winding resistance test check the motor winding resistance or ohms reading with a multimeter.

If you have a reading and your motor isn t operating it s certain the motor is the problem and needs replacing. The only thing you can check is that you ve got the proper line voltage with a heavy load such as the humming motor connected. 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. 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.

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. With a multimeter set to low ohms usually 200 test between each winding terminal and the metal casing of the motor. It measures the same or similar to the voltage you noted from the label on the electric motor if power is reaching the motor.

Additionally along with these tests you will also have to test your voltage contacts contact check terminal check etc. Since there are three terminals. You may find that when it runs ungrounded that the casing becomes live at up to supply voltage. Keep the multi meter set for 30 000 ohms and touch one test lead to one terminal and the other to another terminal.

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 for direct shorts in the motor s power windings in induction non brush type motors. Even though you may have to do a bit of work by splitting the coupling this test will really help you to find out if the motor is bad or good since it is not usual for a bad motor to run off load.