Gas flow–switching arc interaction in HV synchronous gas blast interrupters

Abstract

The paper is devoted to the solution of short-circuit switching problem in distribution networks by application of synchronous HV gas-blast circuit breakers (SCB). The reduction of the arcing energy by reducing the arcing time can extend the SCB expected service life by increasing its electrical life, minimizing the thermal requirements of the interrupting chamber. The paper studies the gas flow arrangement in the switching gap of the double-flow model SCB. Well-balanced and stable gas flow removes surplus energy from the switching arc. Three types of nozzle geometry are investigated. A numerical simulation with a grid reconstruction is used. A gas flow energy accumulation into the nozzle throats is observed at t=0.8-0.9 ms after the contacts opening. We evaluate the bottom time limit of the active interactions between the gas flow and the arc column before current zero under the synchronous commutation. A zone of stagnation depends on the nozzle shape and size and determines the level of the thermal-dielectric interruption ability.