Metal-oxide surge arresters for gas-insulated systems, phases 1 and 2

A metal-oxide surge arrester for gas-insulated systems is contained in SF6 gas in an aluminum enclosure which is designed to connect directly to a port in a gas-insulated substation. A technique was developed for soldering metal oxide varistor (MOV) blocks together for strength and simplicity in assembly. Three 362kV prototype arresters were assembled, each using three parallel columns of these soldered 50-mm blocks. Continuous testing for 72 h at a-c voltage in the range of 209 V to 285 kV confirmed the predicted operation and thermal stability of this prototype design. The behavior of this arrester in typical power systems applications are shown by computer calculations for lightning surges and switching operations. The expected effects of seismic activity and internal fault arcs are also derived. Basic characteristics of gas-insulated metal-oxide arresters for 69 kV, 138 kV, 230 kV and 500 kV were also derived.