Evaluation of the influence of rotor magnetic anisotropy on condition monitoring of 2 pole induction motors

Sungsik Shin, Jongwan Kim, Sang Bin Lee, Chaewoong Lim, Ernesto J. Wiedenbrug

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Citations (Scopus)


Non grain-oriented silicon steel laminations used in electric machines show a small degree of non-ideal magnetic anisotropy, which is introduced during the rolling process. If the rotor laminations are punched and stacked in a uniform direction, magnetic asymmetry is present in the rotor core. In this paper, it is shown that rotor core anisotropy can produce twice slip-frequency, 2sf<inf>s</inf>, modulation that can be misinterpreted as rotor faults in 2 pole induction motors when performing motor current signature analysis (MCSA). Unnecessary motor inspection due to false rotor fault alarms is a common on-going problem in the field, and it is shown for the first time in this work that rotor anisotropy is a root cause of false MCSA alarms in 2 pole induction motors. The influence of rotor core anisotropy is analyzed in detail, and it is shown that 2sf<inf>s</inf> components produced by the rotor fault and rotor anisotropy interact, making reliable fault detection difficult with MCSA. It is also shown that off-line testing is currently the only available means of detecting the fault, and on-line monitoring of the space harmonics-induced current components is proposed as a viable solution for providing reliable rotor fault detection for 2 pole motors with rotor anisotropy. The analysis and conclusions presented in this paper are verified through testing on custom built lab motors and on 3.3 kV motors.

Original languageEnglish
Title of host publication2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages8
ISBN (Print)9781479956982
Publication statusPublished - 2014 Nov 11

ASJC Scopus subject areas

  • Fuel Technology
  • Energy Engineering and Power Technology


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