New Electrical Devices in Existing Nuclear Power Plants

Numeric protective relays are superior to older technologies regarding the increased functionality and flexibility. They have the potential to increase the performance of the protection but also if not implemented with care a risk of malfunction.

SF₆ and vacuum are practically the two available technologies and have today replaced older types of breakers. The use of SF₆ as a quenching medium is decreasing, much for environmental reasons. The risk of overvoltages with vacuum circuit breakers and the required protective measures might prohibit the use in safety classified applications at Nuclear Power Plants.

Surge arresters of metal oxide have made silicon carbide arresters obsolete. Metal oxide arresters have superior energy handling capacity and protective capability over previous technologies. Silicone housing which is used for metal-oxide surge arresters have almost ideal properties.