Structural looseness investigation in slow rotating permanent magnet generators

Georgios Alexandros Skrimpas, Nenad Mijatovic, Christian Walsted Sweeney, Christian B. Poulsen, Joachim Holbøll

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

Structural looseness in electric machines is a condition influencing the alignment of the machine and thus the overall bearing health. In this work, assessment of the above mentioned failure mode is tested on a slow rotating (running speed equal to 0.7Hz) permanent magnet generator (PMG), while collecting vibration and current data in order to cross-reference the indications from the two monitoring techniques. It is found that electric signature analysis shows no response even when two hold down bolts are untightened, whereas the analysis results from the vibration data exhibit superior performance. The vibration-based condition indicators with the best response are the stator slot pass frequency, which can be directly related to the cogging torque in PMGs, and the 4th electric frequency harmonic, whose amplitudes increase due to the overall lower structure damping coefficient under looseness. The theoretically expected frequencies in the vibration signal related to rotor dynamics issues, i.e. speed harmonics, do not respond to the imposed faults.
Original languageEnglish
Title of host publicationProceedings of 2016 XXII International Conference on Electrical Machines
Number of pages7
PublisherIEEE
Publication date2016
Publication statusPublished - 2016
Event2016 XXII International Conference on Electrical Machines - SwissTech Convention Center, Lausanne, Switzerland
Duration: 4 Sep 20167 Sep 2016

Conference

Conference2016 XXII International Conference on Electrical Machines
LocationSwissTech Convention Center
CountrySwitzerland
CityLausanne
Period04/09/201607/09/2016

Keywords

  • Condition monitoring
  • Vibration analysis
  • Electric signature analysis
  • Structural looseness
  • Stator slot pass frequency
  • Cogging Torque

Cite this

Skrimpas, G. A., Mijatovic, N., Sweeney, C. W., Poulsen, C. B., & Holbøll, J. (2016). Structural looseness investigation in slow rotating permanent magnet generators. In Proceedings of 2016 XXII International Conference on Electrical Machines IEEE.