On-Line Digital Computer System for Measurementof Partial Discharges in Insulation Structures

An outline is given of the nature of partial dischargesoccurring in insulation structures, in particular in oil impregnatedconfigurations. It is suggested that conventional discharge measuringsystems are not always able to assess significant parameters becausemuch of the available information is inevitably discarded during thehigh-voltage tests. A mobile computer-based data-acquisition system hasbeen developed for recording and storing, in digital form, the statisticalinformation present. The equipment described is capable of recordingand analyzing the small disturbances produced by partial dischargesunder practical conditions. The computer programs enable the time ofoccurrence and the magnitude and polarity of the pulses to be recorded;in addition, digital transient-event recorders can be programmed toaccept slow partial discharge shapes or ultrasonic transducer outputsfor storage in the computer system. A wide range of playback programsare described and possible methods of presenting the results are discussedusing examples obtained from a 50-kV high-voltage test arrangement.The problems of hardware development are outlined, including thoseof interfacing and operation in hostile environments. The economics ofsuch a system are mentioned and methods of effecting cost reductionsare suggested.Finally, this paper suggests that if on-line characterization of partialdischarges becomes possible then the results of discharge measurementswill have greater significance than at present, especially in those borderlinecases where interpretation of results is difficult.