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

19 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

Bibliographical note

Funding Information:
Manuscript received November 6, 2017; revised January 4, 2018; accepted February 1, 2018. Date of publication February 5, 2018; date of current version May 18, 2018. Paper 2017-EMC-1392.R1, presented at the 2017 IEEE 11th International Symposium on Diagnostics for Electrical Machines, Power Electronics, and Drives, Tinos, Greece, Aug. 29-Sep. 1, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Electric Machines Committee of the IEEE Industry Applications Society. This work was supported by the Human Resources Program in Energy Technology of the Korea Institute of Energy Technology Evaluation and Planning granted financial resources from the Ministry of Trade, Industry, and Energy, Republic of Korea, under Grant 20154030200610. (Corresponding author: Sang Bin Lee.) H. Kim and T. Kong are with the Korea Electric Power Corporation Research Institute, Daejon 305-760, South Korea (e-mail: hdkim90@kepco.co.kr; tskong@kepco.co.kr).

Publisher Copyright:
© 1972-2012 IEEE.


  • 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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