A continuous UHF monitor for gas-insulated substations

Assessing the condition of a GIS by measuring the UHF signals generated in it by partial discharges gives warning of developing faults. The signals are taken from couplers built into the equipment. The couplers are continuously monitored using special amplifying and detection units connected in a digital optical fiber network. The data collected can also be interpreted by an expert system and an analysis of the situation sent via a modem link to a PC. Laboratory trials of the continuous monitor have been carried out on a test rig of 400-kV GIS chambers. The basic principles of the monitor and the results of its trials are given.<
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