Optical discharge detection in SF6-insulated systems

A description is given of an optoelectronic system for detecting and locating corona discharges in SF₆-filled gas-insulated systems (GIS). The system consists of optical fiber links, photomultiplier light detectors, an operational amplifier, and a computer-based data collection system. Various factors that can influence the optical discharge detection sensitivity are investigated. It is shown that an optical system can detect discharges that are located even in the hidden areas in GIS. The detector can sense corona discharges of <5 pC located at distances of ⩽50 cm. For application of this technique to large practical systems, it will be necessary to use multiple-access windows and/or suitable additives that could enhance the light emission without reducing the insulation performance of the system. The optically measured discharge onset voltages are verified using conventional electrical discharge detection techniques