Electromagnetic Disturbances of the Secondary Circuits in Gas Insulated Substation due to Disconnector Switching

The paper describes problems with electromag- netic compatibility (EMC) of the secondary equipment in the 123 kV gas insulated switchgear (GIS). The causes for malfunctioning of the busbar protection during disconnector switching have been studied. Thorough measurements and computer simulations were conducted in order to determine magnitudes and frequencies of the transient voltages and currents in the secondary circuits. Although measured secon- dary transients had lower magnitudes than allowed, they caused malfunctioning of the secondary equipment, e.g. bus- bar protection. Continuous monitoring of the HV equip- ment's influence on the secondary equipment and implemen- tation of some precautionary protection measures are rec- ommended.