Analysis of acoustic signals generated by partial discharges in insulation oil

This paper dealt with the frequency analysis of acoustic signals generated by partial discharge (PD) in insulation oil and the positioning of PD occurrence to apply in the diagnosis of oil insulated transformers. We assembled three types of electrode system; the needle-plane, the plane-plane, and the floating to simulate partial discharge in insulation oil. An acoustic signal detection device was designed to detect acoustic signal with high sensitivity. As a result of frequency spectrum analysis, the frequency ranges of acoustic signal were 70 kHz~210 kHz in the needle-plane, 80 kHz~270 kHz in the plane-plane, and 60 kHz~193 kHz in the floating electrode. Their main frequencies were 132 kHz, 130 kHz and 126 kHz, respectively. The position of PD occurrence was calculated by the time difference of arrival (TOA) using three acoustic emission (AE) sensors and we could find the position about the error of 1% in the experimental apparatus.