Improved Transient Model of Prestrikes Encountered in 10 kV Vacuum Circuit Breakers and Its Application to Overvoltage Suppression while Switching on Shunt Reactors

Abstract

A 10 kV vacuum circuit breaker (VCB) experiences prestrikes when its contacts are closing. Prestrikes can cause a high frequency (HF) and steepness overvoltage, which compromise the insulation of electrical devices. The transient prestrike process should be accurately simulated to effectively design and evaluate overvoltage suppression measures. The improved prestrike model was modeled in ATP-EMTP based on on-site measurement prestrike data. The model was applied to compare various overvoltage suppression measures in terms of the effectiveness. The simulation results showed that an RC snubber and a surge arrester can be installed to suppress the overvoltage amplitude on the substation transformer (ST) and shunt reactor (SR) sides. The RC snubber can reduce the oscillation frequency of the overvoltage compared with the surge arrester. Finally, the RC snubber and surge arrester were installed on the ST and SR sides as part of a field test to verify the simulation results. Reasonable suggestions are provided for switching overvoltage suppression through the simulation and experimental results.