Electric circuit breaker capable of circuit-breaking when detecting arc and over-load

Power-off apparatus according to an embodiment of the present invention is fine arc from the high-frequency pulse, and by the current conduction of the first switching element based on the voltage induced in a high frequency choke coil, a first switching element in a conductive micro-arc while on the power line large current arc detector for because of high current on the micro-arc detector, a power line for outputting the detected current arc furnace outputs the high-current arc detection current while the second switching device conductive based on a variation of the magnetic field takes place in a coil inserted in a power line, a fine sikimyeo arc detection current or large current arc with a predetermined time constant to the detected current to the delay capacitor charge cumulatively, the delay unit the voltage of the delay capacitor for outputting the arc detection signal reaches a predetermined level, if the operating voltage applied to the load side and power-off portion to block a power line electrically And it may include a first switch for connecting the operating voltage to the sub power-down by the arc detection signal.