Partial discharge acoustic emission detector based on computer for power capacitor

A computer-based digital measuring system for detecting partial discharge (PD) within a power capacitor is introduced in this paper. The principle and construction of this instrument and some results obtained from typical discharge experiments are given. The electrical signal caused by PD in a capacitor with large capacity is very weak; therefore this system is based on acoustic emission (AE) method and detects the acoustic pulse signal caused by PD. Mass capacity, high-speed synchronous A/D (analog/digital) converter cards are used to record the acoustic signals and this makes the subsequence processing possible. Through a series of processing, the frequency spectrum of PD signals, the discharge waveform information and the PD characteristic reflected by φ-q-n chart (φ: occurring phase, q: discharge amplitude, n: repetitive rate) could be extracted. Some feature extracting methods such as waveform feature analysis, frequency spectrum analysis and artificial neural network used as a classification tool are applied to recognize the discharge pattern. The study results could provide reference for a factory to improve manufacturing technologies