Experience with Stator Insulation Testing and Turn/Phase Insulation Failures in the Power Generation Industry

Heedong Kim, Taesik Kong, Sang Bin Lee, Tae June Kang, Namyoung Oh, Yeongjae Kim, Sanguk Park, Chaewoong Lim, Greg C. Stone

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


The reliability of medium voltage (MV) motors used for driving pumps, fans, and other loads in the power generation industry is critical for continued power production. Periodic testing of stator winding insulation, which is the most vulnerable component in MV motors, is an essential part of predictive maintenance for preventing unplanned reduction in the power generation capability. Korea Electric Power Corporation (KEPCO) Research Institute's 17+ years of experience on predictive maintenance of stator insulation for MV motors is presented in this paper. KEPCO's stator insulation test program and statistics of test records are summarized, and cases of recent turn and phase insulation failures that resulted in motor forced outages are investigated. Analysis of the turn or phase insulation failures and insulation test records performed on the failed motors show that it is difficult to predict turn or phase insulation failures with the insulation tests currently performed. Turn or phase insulation test methods are summarized and evaluated based on the findings of the investigation to help target future research efforts toward industrial needs.

Original languageEnglish
Pages (from-to)2225-2236
Number of pages12
JournalIEEE Transactions on Industry Applications
Issue number3
Publication statusPublished - 2018 May 1


  • AC machines
  • phase insulation
  • predictive maintenance
  • stator insulation testing
  • turn insulation

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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