Combination of frequency spectrum analysis and partial discharge pattern recording

The phase resolved partial discharge detection technique (or `pd pattern recording technique´) is applicable to field measurements, particularly if combined with disturbance rejection techniques and non-conventional pick-up circuits. Electromagnetic disturbances can be eliminated by filtering in the time domain (impulse noise gating) and/or in the frequency domain (down-mixing). The pd patterns not only help to identify the defect type but also serve to evaluate the efficiency of the disturbance rejection procedure