Electric Motor Rewind

Electric Motor Rewind Service

Rewinding a motor is the last desparate step to take in repairing a motor. You can't usually tell if a motor needs rewinding by looking at it. Motors need to be rewound for two reasons: because excess heat has damaged the insulation so that electricity passes from winding to winding without going thru them all, or else because the winding has been cut in a place that is not near the end of the coil. Determining if a motor needs to be rewound requires some special equipment - an AC ammeter and a 1 volt AC power source.

Rewind A Failed Motor?

Although failed motors can usually be rewound, it is often worthwhile to replace a damaged motor with a new energy-efficient motor to save energy and improve reliability. When calculating operating costs for rewound motors, deduct one efficiency point for motors exceeding 40 hp and two points for smaller motors. In general, it is best to replace a motor if it is less than 40 hp, the cost of the rewind exceeds 65 percent of the price of a new motor, or the motor was rewound prior to 1980.

Have motors rewound only at reliable repair shops that use low temperature (under 700 degrees F) bakeout ovens, high quality materials, and quality assurance programs based on EASA-Q or ISO-9000. Ask the repair shop to conduct a core loss or loop test as part of their rewind procedures.