Rewinding Motor

When a motor is rewound, the motor's efficiency can be affected unless a quality rewind is specified.

Using a quality rewind, the motor should be near or better than its original efficiency.  However, reductions in efficiency from rewinding motors can occur if substandard rewind methods are used. Several rewind rules of thumb are typically used for motor comparison:

• Motor stator cores damaged by excessive heat may not result in a quality rewind. A good motor service center can test motor stator cores damaged by excessive heat to determine if they are good candidates to be rewound.
• Consider replacement of general purpose motors that are less than 50 horsepower and more than 15-years-old.
• If rewinding costs more than 60% of the price of a new premium efficient motor, buy the new motor.

These decisions generally yield increased reliability and lower operating costs.  As a reference point for a good motor rewind, look for service centers that adhere to ANSI/EASA AR100-2006: Recommended Practice for the Repair of Rotating Electrical Apparatus (available for download under “Industry Info” at www.easa.com) and that utilize EASA-Q or ISO 9000 quality standards and methodologies. A host of other excellent resources on this topic are available at www.easa.com to help you assure a quality rewind or repair.

And Furthermore . . .