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.