How to Check the Motor Winding Resistance

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Use a digital multimeter to measure resistance.

An electrical induction motor contains windings, or wire wrapped around a cylindrical shaft. When an electric current flows though the wire, a magnetic field is induced inside the coil of wire. This magnetic field causes a metal bar inside the coil to rotate and power the motor. To operate correctly, the coiled wire should have a predetermined resistance specified by the manufacturer. This resistance allows just the right amount of current to flow through the coil. You should regularly check the resistance of the windings in a motor to be sure its operating at peak ability.

Step 1

Turn on the digital multimeter.

Step 2

Turn the measurement setting dial on the multimeter to resistance. The resistance setting is designated by the capital Greek letter, omega. Capital omega is the symbol for the resistance unit ohm.

Step 3

Touch the red (positive) lead of the multimeter to the positive end of the wire windings around the motor.

Step 4

Touch the black (negative) lead of the multimeter to the negative end of the wire windings around the motor. The reading that appears on the multimeter screen is the resistance in ohms.

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