Influence of resistance of electric arc on transients due to disconnector switching in air-insulated substations

Switching overvoltages due to disconnector switching in air-insulated substations are presented. Shapes and levels of switching overvoltages by means of experimental and computing investigations on 220 kV switchyards of Public Enterprise Elektroprivreda BiH are presented. The influence of resistance of electric arc between the contacts of disconnector is analysed. Computer simulations by means of EMTP-ATP [1] are performed. Differences between the measured and the calculated values were under 4.52% for overvoltage factor, and under 2.56% for overvoltage wave frequency. Comparison of the transient computer simulations with the field measurements showed that calculations could be used for assessment of the transient overvoltages caused by disconnector switching.