NEW METHOD FOR MEASURING STATISTICAL DISTRIBUTIONS OF PARTIAL DISCHARGE PULSES

A new digital detection system is described for measuring pulsating pa rtial discharges (PDs). The PD detection system can continuously recor d all PD pulses that occur over extended periods of time, with a minim um inter-pulse time separation of 6 mu s and a vertical amplitude reso lution of 12 bits. Earlier PD detection systems detected PD pulse ampl itude and time using complex custom-designed hardware while the presen t system continuously records the complete electrical waveform that ca rries the PD pulses using a commercial data acquisition board and extr acts, in real time, the time and amplitude information of all PD pulse s in software. The current approach considerably reduces the developme nt and maintenance cost of the PD detection system, significantly incr eases the system portability and may prove to be a crucial step for tr ansferring the digital PD detection and analysis technology developed in laboratories to industry. The features of the new system are illust rated by the study of dc-excited PD pulses occurring in a point-to-pla ne gap in air. A new surface-mediated burst mode of PDs is discovered in which a PD pulse has a certain probability to induce another pulse. The probability is determined for several gap voltages and is found t o vary strongly with the applied voltage.