Acoustic Measurements of Partial Discharge Signals

Abstract

Abstract: The acoustic pressure waves associated with partial discharges in HV power transformers can be detected with external piezoelectric sensors. The propagation time and the waveshape of the received signals are affected by factors such as the sensor position, internal barriers and sensor type. These are investigated in this paper. In particular, it is shown that the commonly-used resonant sensor gives a cleaner signal. On the other hand, the wideband sensor enables comparison between low and high frequency components. It was found that as the sensor is closer to the normal, the higher frequency components become more dominant. This can be utilised as a new diagnostic method for discharge location. The wavelet transform is used to show changes in the frequency distribution via the time-scale plot and also to de-noise the signal. 1.