Application of optical methods for diagnostics of partial discharges

Abstract:
Partial discharge (PD) diagnostics is a commonly accepted procedure in the electric power generation and delivery industry. The typical rise times of a single discharge event of sub-nanosecond scale represent a challenging task for measurements of the current pulse form. The optical signals do not suffer on the transmission line limitations. This work concentrates on the precise measurements of both the electric current of an individual PD and the optical signal produced by PD event. It is shown that optical signals carry the same information as conventional PRPD diagrams. The light pulses from single discharge events were registered by a photomultiplier. In addition, the discharge images have been acquired by iCCD cameras with single and double stage amplification. Analysis of obtained discharge patterns in dependence on used material and electrode polarity will be presented. Results of optical measurements are compared with conventional PRPD patterns. There exist different correlation modes between intensities of light and current pulses of partial discharges, which can be ascribed to different type of defects. Distinction between volume and surface discharges can be principally performed.