1 Metal-Oxide Surge Arresters Integrated in High-Voltage AIS Disconnectors – An Economical Solution for Overvoltage Protection in Substations –

In high-voltage transmission systems instrument transformers and circuit-breakers during the dead time of an auto-reclosing cycle are frequently damaged by direct multiple lightning strokes into the conductors of overhead lines nearby a substation. These devices can be protected by ar-resters at the line entrance. An efficient and economical solution of a standard arrester integrated into a standard disconnector is covered here, which allows the arrester to be installed without addi-tional space requirements. The new device has been applied in 245-kV- and 420-kV-systems so far. Only for the 420-kV-system some modifications to the grading ring of the arrester had to be intro-duced. This paper presents information on the requirements on the disconnector/arrester, the realiza-tion and the investigations and tests performed. The protective characteristic is verified by EMTP calculations based on models derived from full scale tests in the high-voltage laboratory.