With the ever increase of power grid capacity

the time constant of DC component of short-circuit current in power system is likely higher than its standard time constant by 45 ms.At present

rule of influence of DC component of asymmetric short-circuit current on the key parameters of the circuit breaker at arcing stage has not been studied yet.Therefore

the study objective of this paper is to obtain the rule of influence of DC component of short-circuit current on the key parameters of circuit breaker at arcing stage.The arc physical enthalpy current simulation model based on the internal structure of a high-voltage circuit breaker is set up so to study the law of change of such key arc parameters in the arcing stage as arc length

the pressure of gas compartment and the mass flow of gas at the nozzle of gas circuit breaker respectively in case of interrupting symmetrical current and asymmetrical current by the circuit breaker.The study results show that

in case of identical arcing time

the variation of arc length in asymmetrical current interruption is less than that in symmetrical short-circuit current.However

the pressure in gas compartment and gas mass flow only slightly increase during arcing period.While

under the same opening instant

the arcing time in asymmetrical short circuit current interruption is probably longer than in symmetrical short circuit current interruption

causing arc length

pressure of gas compartment and the mass flow of gas at the nozzle to increase exponentially.However

under the condition of either same arcing time or same opening instant

the change of above-mentioned key parameters keeps the variation of interrupting capability of circuit breaker

which is obtained by the KEMA black box arc model of circuit breaker

significantly less than the magnitude of interruption capability which the circuit breaker needs reaching by the increase of DC component of short circuit current.The study results explain the reason why the interruption of the circuit breaker tends to be failure in case of interrupting the short-circuit current with high DC component and provide a theoretical basis for improving the asymmetrical short circuit current interruption capability of high voltage circuit breaker.