Study on reignition characteristics of 126 kV vacuum circuit breaker with triple breaks

Abstract

Starting from a transient equivalent model of a triple-break 126 kV vacuum circuit breaker (VCB) containing a dielectric reignition criterion, the reignition current waveform of the vacuum interrupter (VI) which took over the higher part of the transient recovery voltage (TRV) was simulated. A series damped resistor was added in the grading capacitor branch to extinguish the reignition current as early as possible. The results show that the effect of the damped resistor is optimal when its value is threshold between oscillatory and non-oscillatory decay. Excessive TRV which appeared across other un-reignition VIs and power frequency recovery voltage (PFRV) which appeared across the reignition VI were simulated. A metal oxide arrester (MOA) was installed in parallel with each VI to ensure breaking successfully by limiting the excessive TRV and PFRV. It is shown that the voltage limiting effect is preferable when a MOA with the reference voltage of 50 kV is in parallel with a grading capacitor of 1000 pF, also the thermal limit can be satisfied. Research results are expected to provide a basis for choosing proper dynamic voltage sharing measures for a triple-break 126 kV VCB.