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Method for detection of interlaminar sheet short circuits in the stator sheet core of electromachines

  • US 9,146,279 B2
  • Filed: 06/04/2010
  • Issued: 09/29/2015
  • Est. Priority Date: 12/07/2007
  • Status: Active Grant
First Claim
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1. A method for detection of interlaminar laminate shorts in a laminated stator core of electrical machines, the method comprising;

  • subjecting the laminated stator core to an externally applied field current or field voltage;

    measuring, with a sensor coil, a short-circuit magnetic field induced by short-circuit currents the sensor coil being arranged in a gap in a machine and probes the gap, wherein the field current and field voltage have a non-sinusoidal shaped waveform, and the non-sinusoidal shaped waveform of the field current or field voltage is a periodic waveform with significant higher harmonics; and

    evaluating both a fundamental frequency and a harmonic of a signal produced by the sensor coil, subjecting the signal recorded in the sensor coil to spectral analysis with assistance of a Fourier transformation for identification of the interlaminar laminate shorts, and using a phase spectrum of various harmonics for identification of the interlaminar laminate shorts on a basis of phase angles in individual harmonics of the various harmonics.

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