Partial discharge signal conditioning techniques for on-line noise rejection and improvement of calibration [machine insulation tests]

Noise rejection and calibration are preconditions for comparable and reproducible partial discharge measurements performed on operating power equipment in the field. Wide and narrowband frequency domain signal processing techniques serve to precondition partial discharge (PD) signals such as they can be processed by peak detectors and pulse counting devices or conventional PD detectors. Frequency domain signal conditioning serves to suppress electromagnetic noise such as radio interference or impulse type noise and, at the same time, may enhance or reduce the calibration uncertainty created by resonance effects in spatially extended test objects. This paper outlines the principle of frequency domain conditioning and gives practical examples of online partial discharge measurements on electric generators.