A Green Motor Rewind is the rewinding of an induction motor that is intended to preserve its original efficiency. Green practices include tight control of the burn-off process, stator core loss testing and repair, and performance criteria for the windings. Standard rewind practices can result in a decrement in efficiency relative to the original efficiency due to degradation of stator core laminations, splayed stator core teeth, increased winding resistance losses, and increased bearing friction losses. The Green Motors Practices Group certifies service centers as members, and certifies individual rewinds at member service centers when they have been documented to meet the Green Rewind specifications. Eligible motors are low-, and medium-voltage squirrel cage induction motors between 15 and 5,000 HP with undamaged stator cores and rotors.
Energy consumption estimates in this analysis are based on motor usage information from the industrial audits conducted by Oregon State University’s Industrial Assessment Center, and from Bonneville Power Administration research on agricultural pump motors. The efficiency degradation of a standard rewind is informed by a study on this topic sponsored by the Electrical Apparatus Service Association, Inc. and The Association of Electrical and Mechanical Trades in 2003. The current practice is estimated from the Northwest Energy Efficiency Alliance’s 2016 motor rewind market study.