The policy of CONEL Romania-ST Sibiu about protection against switching and lightning overvoltages

The protective devices use at ST Sibiu against overvoltages are: gapped silicon carbide (SiC) arresters and metal oxide surge arresters (MOSA). This paper discusses the standards and rules used by CONEL Romania for choosing and testing surge arresters. The construction, operating principle and modelling of MOSA are then discussed. The field experience and some outage examples of MOSA in Romania are also discussed.