Patent ID: 6812716
Filing Date: 2004-11-02
Classification: G01R

Abstract:
A method of measuring the insulation impedance of a capacitative electrical component at a power line frequency comprising the steps of generating a test signal having a composite waveform consisting of two sinusoids at first and second frequencies respectively above and below said power line frequency, applying said test signal to a test circuit including said electrical component, sampling the applied test signal, synchronously with the generation thereof, at a sampling frequency that is an integer multiple of each of said first and second frequencies, for a sampling period corresponding to an integral number of cycles of each of said first and second frequencies, in order to derive and store corresponding digital values of said applied test signal, calculating, from said stored values, for each of said frequencies, values of voltage applied to and current flowing in said electrical component in order to derive respective values corresponding to the insulation impedance of the component at said frequencies, and interpolating from said derived values to obtain a value at the power line frequency.