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Benefits of the AC hi-pot for new form coil stator windings

Publication date: 
August 2013
Author: 
Mike Howell, EASA Technical Support Specialist

The October 2012 Currents article titled "How to properly test AC stator and wound rotor windings" provides a thorough explanation on the proper application of insulation resistance, winding resistance, surge testing and high potential testing for stators and wound rotors. The article emphasizes that NEMA MG 1-2011 specifies AC and DC high potential (hi-pot) test levels for new windings and does not recommend repeated application of the high potential test. This is reinforced in EASA's Recommended Practice for the Repair of Rotating Electrical Apparatus (ANSI/EASA AR100-2010) which calls for reduced voltage levels for repeated tests should they be required. This article is intended to provide additional information on the high potential test performed on new windings. Specifically, it addresses the advantages of AC high potential testing for new, form coil stator windings. Topics discussed include:

  • A real-world example
  • Destructive test?
  • Sizing the AC test set
  • Example calculation
  • Bibliographic references to additional reference materials
Topic(s): 
AC motors
Form wound
Testing
Motor testing