Search Coil-Based Detection of Nonadjacent Rotor Bar Damage in Squirrel Cage Induction Motors

Yonghyun Park, Hanchun Choi, Sang Bin Lee, Konstantinos N. Gyftakis

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


Detection of rotor cage faults in induction motors based on motor current signature analysis (MCSA) is being extensively applied in the field for preventing forced outage of the motor and industrial process. Although MCSA is very effective for detecting broken bars that are adjacent to each other, it can fail if the broken bars are nonadjacent, which is common for applications with frequent starts. If multiple broken bars are spread out at locations where the rotor 'electrical' asymmetry is canceled, the presence of broken bars is difficult to detect with MCSA. A false indication can lead to a catastrophic-forced outage, but the only known means of detecting this type of fault in the field is through rotor visual inspection. In this article, the feasibility of detecting nonadjacent broken rotor bars from the rotor rotational frequency sideband components in the internal and external search coil measurements during steady state and motor starting is evaluated. Experimental testing on a 7.5-hp induction motor shows that nonadjacent broken bars can be reliably detected from the analysis of flux measurements for cases where MCSA and all other electrical tests fail.

Original languageEnglish
Article number9110782
Pages (from-to)4748-4757
Number of pages10
JournalIEEE Transactions on Industry Applications
Issue number5
Publication statusPublished - 2020 Sept 1


  • Airgap flux
  • fault diagnostics
  • induction motor
  • offline testing
  • search coil
  • spectral analysis
  • squirrel cage rotor
  • starting transient
  • stray flux

ASJC Scopus subject areas

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


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