Online Airgap Flux Based Diagnosis of Rotor Eccentricity and Field Winding Turn Insulation Faults in Synchronous Generators

Muhammad Faizan Shaikh, Han Ju Kim, Sang Bin Lee, Chaewoong Lim

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Rotor faults in a synchronous generator severely deteriorate its performance, reducing the operation efficiency and reliability. Most of the field-wide accepted methods require stoppage of generator operation and disassembly, and online diagnosis of rotor faults is difficult due to the lack of dependable online methods for sensitive rotor fault detection. Therefore, online methods that can reliably and unambiguously detect rotor field winding and eccentricity faults before they lead to machine failure are required. This paper presents a new method for detecting and distinguishing rotor field winding insulation and eccentricity faults online during synchronous generator operation based on measurements from airgap flux probes, which are installed in most synchronous generators used for electric power generation. A non-complex, time domain analysis method is proposed which makes use of the voltage induced in the airgap flux sensor for a reliable prediction of the presence and identification of rotor field winding turn insulation failure and rotor dynamic eccentricity. The method is tested and verified experimentally on a 5 hp synchronous generator and on measurements from a 330 MW pumped storage generator.

Original languageEnglish
Pages (from-to)359-366
Number of pages8
JournalIEEE Transactions on Energy Conversion
Issue number1
Publication statusPublished - 2022 Mar 1

Bibliographical note

Publisher Copyright:
© 1986-2012 IEEE.


  • Synchronous generator
  • airgap flux
  • eccentricity
  • fault diagnostics
  • field winding
  • online condition monitoring

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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