Comparison of two voltage-sharing measures for triple-break vacuum interrupters in series

Multiple-break vacuum circuit breaker (VCB) has been identified as an effective way to expand from the present low and middle voltage level to high voltage level, where the SF6 gas-blast circuit breaker is widely used. However, in multiple-break VCB in series, the voltage applied to each break does not become equal because of stray capacitance, opening non-synchronously or differences of contact property, which is detrimental to breaking capacity. An enhanced PSCAD/EMTDC model of simulating dielectric recovery process of signal and triple-break vacuum interrupters was developed, whose accuracy was verified by comparing simulation results with test data obtained by Edward Huber. The other research focused on choice of rational voltage sharing measures for triple-break vacuum interrupters. Two voltage-sharing measures for triple-break vacuum interrupters including shunt grading capacitor and metal oxide arrester (MOA) were investigated and compared. It is advised that both shunt grading capacitor and MOA should be considered to be installed.