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A systematic approach to AC motor repair

Publication: 
Plant Engineering
Publication date: 
March 2015
Author: 
Tom Bishop, P.E., Electrical Apparatus Service Association

 
The only national standard for repair of motors and generators is ANSI/EASA AR100-2010: Recommended Practice for the Repair of Rotating Electrical Apparatus (AR100). It provides best practices for mechanical repair, electrical repair including rewinding, and testing that help apparatus rebuilders maintain or enhance the performance, reliability, and energy efficiency of ac and dc motors and generators.

The focus in this article is on the electrical aspects of AC machine repair that this standard prescribes, and that form the basis of EASA’s new service center accreditation program.

Many of the good practices in AR100 that help maintain motor reliability and efficiency were identified through a comprehensive rewind study that was published in 2003 by EASA and the Association of Electrical and Mechanical Trades (AEMT), a United Kingdom-based service center association.

One value of AR100 for end users is that it describes “good repair practices” in just 22 pages. Another is that by requiring service centers to comply with these practices, end users can be sure repairs will conform to the requirements of a recognized American national standard. Further, the good practice recommendations in AR100 cited in this article are mandatory requirements in the EASA accreditation program. End users who choose EASA-accredited service centers also have the assurance of a third-party audit that these requirements will be met.

Topics covered in this article include:

  • Rewinding
  • Winding data
  • Stator core testing
  • Winding removal
  • Insulation system
  • Rewind procedure and slot fill
  • Winding impregnation