Patent ID: 9018970
Filing Date: 2015-04-28
Classification: G01R

Abstract:
1. A method of testing impulse partial discharges in a rotating electrical machine comprising the steps of: placing electrodes on the surface of an insulation layer of a coil conductor series connection area of a coil of the rotating electrical machine, or to the surface of an insulation layer of a coil turn conductor of a coil of a winding of the rotating electrical machine; measuring a waveform of grounding voltage of the coil turn conductor through the medium with an electrostatic capacitance (C measuring a partial discharge, while measuring a voltage developing in the coil or across a winding turn in the coil, from a change in a waveform of the grounding voltage, wherein a capacitor is connected in series with ground and with the insulation layer of the coil conductor series connection area, or the capacitor is connected in series with ground and with the insulation layer of the coil turn conductor; wherein a measurement is made of a grounding voltage waveform applied across the capacitor; wherein the measured grounding voltage waveform is converted to a grounding voltage waveform applied to the winding, by using a voltage division ratio determined from a separately measured ratio (α wherein a partial discharge is measured from a change in the converted grounding voltage waveform, while measuring a voltage applied to the coil and across a winding turn in the coil.