Abstract: The invention relates to a high tension circuit breaker capable of interrupting alternating fault currents which have a pseudo period T. The faults occur at an instant t.sub.0 and delay the zero crossing of the current after a maximum time lapse of t.sub.zmax -t.sub.0. The circuit breaker includes a plurality of interrupting chambers in series. These chambers open at an instant t.sub.1 which is subsequent to the fault instant t.sub.0 and include moving equipment and an arc blaster. The arc blaster operates between instant t.sub.1 and instant t.sub.c, where instant t.sub.c is earlier than the instant t.sub.zmax -T. The circuit breaker also includes a feature which causes blasting to be extended to an instant t.sub.2 lying in the range t.sub.zmax -T and t.sub.zmax +T.