Abstract
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, 2sfs, 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 2sfs 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 language | English |
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Title of host publication | 2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014 |
Publisher | Institute of Electrical and Electronics Engineers Inc. |
Pages | 638-645 |
Number of pages | 8 |
ISBN (Electronic) | 9781479956982 |
DOIs | |
Publication status | Published - 2014 Nov 11 |
Publication series
Name | 2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014 |
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Bibliographical note
Publisher Copyright:© 2014 IEEE.
ASJC Scopus subject areas
- Fuel Technology
- Energy Engineering and Power Technology