Suppression of VFT in 1100 kV GIS by adopting resistor-fitted disconnector

With 1000 kV transmission lines planned in Japan, very fast transient (VFT) phenomena will be suppressed by installing a resistor in a disconnector of gas insulated switchgear (GIS). In this paper the VFT overvoltage suppressing effect of the resistor and the duty required of the resistor are clarified. A 1100 kV resistor-fitted disconnector was tested by constructing a charging current interruption test circuit. It has been clarified that the disconnector accepts the required duty. The disconnector tested is used for the field test.