Patent ID: 9146279
Filing Date: 2015-09-29
Classification: G01R

Abstract:
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.