21 Years Later, UHF Monitoring Comes of Age

The first experiments that set the principles of the UHF technique of detecting partial discharges in gas insulated substations (GIS) were made 21 years ago, when the substation failure rate was higher than now and no satisfactory means of detecting defects in them was available.

Since then the technique has been developed from a laboratory curiosity into a sensitive and practical means of giving an early warning of most impending failures in a GIS, and enabling the high quality of supply demanded by today's customers to be provided.