Abstract:

The short-circuit current in the power gathering area,the core ring network and the load center is close to or even exceeds the interruption capacity of the circuit-breakers,and the DC time constant of the short-circuit current exceeds the rated time constant of the circuit-breakers,resulting in the actual short-circuit interruption capacity of the high-voltage AC circuit breaker is lower than the rated short-circuit interruption capacity.Firstly,the existing methods for checking the interruption capacity of circuit-breakers are discussed.Based on the analysis and study of domestic and foreign standards,a method for checking the interruption capacity based on the last current loop energy is proposed.The results show that the energy equivalence principle of last current loop can better characterize the energy in the process of arc interruption than the full-current equivalence principle.Finally,an assessment strategy of circuit-breaker interruption capacity based on the energy equivalence principle of last current loop is presented.The research content of this paper provides a new solution for checking the interruption capacity of circuit-breakers.

Key words: short-circuit current, DC component, interruption capacity, half wave energy of last current