Detection of stator-slot magnetic wedge failures for induction motors without disassembly

Kun Wang Lee, Jongman Hong, Doosoo Hyun, Sang Bin Lee, Ernesto J. Wiedenbrug, Mike Teska, Chaewoong Lim

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


The recent trend in large ac machines is to employ magnetic stator-slot wedges for improving the motor efficiency, power factor, and power density. The mechanical strength of magnetic wedges is weak compared to the epoxy glass wedges, and many cases of loose and missing wedges have recently been increasingly reported. Magnetic wedge failure deteriorates the performance and reliability of the motor, but there is no method available for testing the wedge quality other than visual inspection after rotor removal. Monitoring of the overall wedge condition without motor disassembly can help reduce the cost of maintenance and risk of degradation in performance. In this paper, a new offline standstill test method for detecting magnetic wedge problems for ac machines without motor disassembly is proposed. An experimental study on 380-V 5.5-kW and 6.6-kV 3.4-MW motors with magnetic wedges is performed to verify the effectiveness of the new test method. It is shown that the new method can provide reliable monitoring of magnetic wedge problems over time, independent of other faults or motor design.

Original languageEnglish
Article number6663678
Pages (from-to)2410-2419
Number of pages10
JournalIEEE Transactions on Industry Applications
Issue number4
Publication statusPublished - 2014


  • AC machines
  • fault diagnosis
  • inverters
  • magnetic wedges
  • nondestructive testing
  • stators

ASJC Scopus subject areas

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


Dive into the research topics of 'Detection of stator-slot magnetic wedge failures for induction motors without disassembly'. Together they form a unique fingerprint.

Cite this