Six years experience with UHF monitoring

The technique of monitoring UHF signals produced by partial discharge in Gas Insulated Switchgear (GIS) was investigated during the mid 1980s at the Central Electricity Research Laboratories, Leatherhead. The author´s company has routinely applied the UHF technique in 20 substations involving numerous site surveys and high voltage commissioning tests as well as a factory test technique. Further investigations have resulted in the development of the Reyrolle `on line´ monitoring system. To date five `on line´ monitoring systems have been installed, two of which are portable and installed on a temporary basis. Remote monitoring of the five systems has been carried out to establish an extensive data base for each substation