1077-2618/11/$26.00©2011 IEEE A good procedure gone astray? BY CHUCK YUNG & TRAVIS GRIFFITH T HIS ARTICLE DISCUSSES THE BASIC components of core loss (hysteresis and eddy-current losses), the effect of frequency and lamination thickness, and other contributing factors. It also explains the effect of operating frequency of squirrel cage type-rotors and armatures and provides correction factors. Stator Cores Although IEEE Standard 432 Guide for Insulation Mainte- nance for Rotating Electric Machinery [1] was withdrawn in 2004, the loop test described in Appendix A4 has long been used to evaluate the suitability of stator cores for rewinding. End users and repair facilities generally agree that this test provides a valid data for evaluating polyphase stator cores designed for 50- or 60-Hz power systems. Specifically, it is used to measure damage or other Digital Object Identifier 10.1109/MIAS.2010.939431 Date of publication: 12 November 2010 © FOTOSEARCH 57 IEEE INDUSTRY APPLICATIONS MAGAZINE  JAN j FEB 2011  WWW.IEEE.ORG/IAS