Gas-insulated surge arrester AZ is constructed from a stack of serially connected – extremely non-linear metal-oxide (MO) resistors in a metallic enclosure under pressurized SF6-gas. The special design with high-field blocks allows reduction of the size of the surge arrester, which is an important factor for GIS.
These surge arresters are designed and type-tested according to IEC 62271-203 and IEC 60099-4.
Surge arresters are used to protect the insulation of gas-insulated switchgear as well as the connecting cables and transformers against transient lightning and switching overvoltages.
The surge current monitoring system SAM 3.0 is capable of sensitively registering surges from lightning and switching in combination with total leakage current. The values are shown digitally on an electronic display. It consists of a current sensor with selectable cable lengths and a display device which can be mounted apart from the arrester.