Detection of Partial Discharge in Oil Filled-Tank using Acoustic in Audio Frequency

Abstract

In this paper, the acoustic emission of partial discharge (PD) in oil contained in the tank was detected by using microphone sensor. PD was generated by point-to-flat electrodes under DC high voltage. The given variables were the DC voltage stress, the electrode gap distance, and the location of PD and sensors. The acoustic and high frequency current were recorded along with the increased voltage. The acoustic signal was then transformed using the fast Fourier transform (FFT) to obtain the frequency spectrum. Furthermore, the acoustic waveforms, the acoustic frequency spectrum, and the PD current were analyzed and correlated. The results showed that the PD could be detected by its audio frequency signal. The impulse-shaped acoustic signal was recognized as a transition condition from normal to PD. The acoustic sensor attached to the outer wall of tank (contact type) was more sensitive than sensor that had a distance from the tank (non-contact type). The perfection level of impulse waveform may indicate the PD location in the oil-filled tank. The signal of acoustic and current did also not affect each other.