Abstract: A ground fault interrupter including a zero-phase current transformer configured to detect unbalanced current flowing in electric lines. A switch is provided in the electric lines. A detection resistor is connected in parallel to the zero-phase current transformer and configured to convert current outputted from the zero-phase current transformer to voltage. A controller is configured to determine based on the voltage of the detection resistor whether an electric leak occurs and to open the switch when the controller determines that an electric leak occurs. At least one filter is provided between the detection resistor and the controller and is configured to remove high frequency elements in the voltage of the resistor. The at least one filter includes an input side resistor connected in series to the controller and configured to limit current input to the controller; and a capacitor connected in parallel to the controller.

Abstract: An abnormal current discriminating method including an arc current detecting method and the apparatus for performing the same in which the arc current method includes the steps of: extracting a predetermined transition pattern specified by the combination of fluctuation patterns of peak values of three continuous half waves from the peak value for each half wave detected from an alternating current flowing to the AC load circuit which is sampled in a predetermined cycle and converted into a digital value, counting the number of appearances of the predetermined transition pattern, and comparing the count value with a predetermined threshold.

Abstract: An abnormal current discriminating method including an arc current detecting method and the apparatus for performing the same in which the arc current method includes the steps of: extracting a predetermined transition pattern specified by the combination of fluctuation patterns of peak values of three continuous half waves from the peak value for each half wave detected from an alternating current flowing to the AC load circuit which is sampled in a predetermined cycle and converted into a digital value, counting the number of appearances of the predetermined transition pattern, and comparing the count value with a predetermined threshold.

Abstract: A ground fault interrupter including a zero-phase current transformer configured to detect unbalanced current flowing in electric lines. A switch is provided in the electric lines. A detection resistor is connected in parallel to the zero-phase current transformer and configured to convert current outputted from the zero-phase current transformer to voltage. A controller is configured to determine based on the voltage of the detection resistor whether an electric leak occurs and to open the switch when the controller determines that an electric leak occurs. At least one filter is provided between the detection resistor and the controller and is configured to remove high frequency elements in the voltage of the resistor. The at least one filter includes an input side resistor connected in series to the controller and configured to limit current input to the controller; and a capacitor connected in parallel to the controller.

Abstract: A circuit breaker includes an arc shearing plate which is driven to thrust between a pair of contacts being separated so as to shear an arc formed therebetween for rapid arc extinction. Included in the circuit breaker is an over-current responsive actuating member which applies an impact to one of the contacts for rapid contact separation in response to a predetermined over-current condition such as caused by a short-circuit. The actuating member is also coupled to the arc shearing plate so as to control the thrusting movement of the arc shearing plate in synchronism with the rapid contact separation, whereby the timing of inserting the plate between the contacts can be easily controlled with respect to that of separating the contacts for achieving rapid arc extinction and providing a high arc voltage and current limiting action.