Permanent partial discharge assessment of power station high-voltage switchgear

Non-intrusive partial discharge monitoring has been installed on two 16kV switchboards at the Ffestiniog hydro-electric pumped storage power station. The circuit breakers control the generators/ motors each operating about 3 times per day and therefore require a very high reliability and availability. The permanent monitoring is intended to provide warning of impending insulation failures and to assist with the management of the assets. The monitor has to be capable of detecting a partial discharge signal of sufficient level to signify possible failure occurring at any time at any of the monitored coupling devices. At the same time the monitor has to he able to discriminate against partial discharge activity from the generator/motors and the 275kV overhead lines.