Patent ID: 8432649
Filing Date: 2013-04-30
Classification: H02H

Abstract:
1. An abnormal current detection circuit for circuit breaker, comprising: a full-wave amplifier for amplifying an alternating current (AC) input voltage signal corresponding to a full-wave AC input current subject to detection, outputting a positive wave-period amplification voltage signal and a negative wave-period amplification voltage signal, and generating a positive wave-period reference voltage signal and a negative wave-period reference voltage signal having a predetermined difference value with respect to the amplified AC input voltage signal; a positive wave-period comparator connected to an output of the full-wave amplifier to compare the positive wave-period amplification voltage signal with the positive wave-period reference voltage signal provided by the full-wave amplifier, and to output a pulse signal when the positive wave-period amplification voltage signal is greater than or equal to the positive wave-period reference voltage signal; a negative wave-period comparator connected to an output of the full-wave amplifier to compare the negative wave-period amplification voltage signal with the negative wave-period reference voltage signal provided by the full-wave amplifier, and to output a pulse signal when the negative wave-period amplification voltage signal is greater than or equal to the negative wave-period reference voltage signal; a combining circuit connected to the positive wave-period comparator and the negative wave-period comparator to combine a pulse signal output from the positive wave-period comparator with a pulse signal output from the negative wave-period comparator, to output a full-wave combining signal; a reference voltage generator for generating a reference voltage signal to determine normality or abnormality of the input voltage signal corresponding to an AC input current subject to detection; a capacitor connected to an output stage of the combining circuit to charge electric charges during the time period that a pulse signal is output from the combining circuit; and a comparative driving circuit section connected to the reference voltage generator and the capacitor to compare a charge voltage provided from the capacitor with a reference voltage signal provided from the reference voltage generator and to output a signal for controlling a circuit breaker to be driven to a circuit breaking position when the charge voltage is greater than or equal to the reference voltage signal, wherein the positive wave-period amplifier comprises: a positive wave-period amplification circuit section for inputting an AC input voltage signal corresponding to a full-wave AC input current subject to detection, and amplifying positive wave-period input voltage signal of the input voltage signal to output a positive wave-period amplification voltage signal; a negative wave-period amplification circuit section for amplifying a negative wave-period input voltage signal of the input voltage signal to output a negative wave-period amplification voltage signal; a positive wave-period reference voltage generation circuit section for generating a positive wave-period reference voltage signal based on a positive wave-period input voltage signal of the input voltage signal; and a negative wave-period reference voltage generation circuit section for generating a negative wave-period reference voltage signal based on a negative wave-period input voltage signal of the input voltage signal, wherein the positive wave-period reference voltage generation circuit section and the negative wave-period reference voltage generation circuit section respectively comprise: a voltage divider circuit section to have a predetermined difference value from a voltage value of the positive wave-period amplification signal or negative wave-period amplification signal outputted from the positive wave-period amplification circuit section or negative wave-period amplification circuit section, wherein the positive wave-period reference voltage generation circuit section and the negative wave-period reference voltage generation circuit are cross connected to the negative wave-period amplification circuit and the positive wave-period amplification circuit, thereby allowing the positive wave-period reference voltage generation circuit to be connected to the negative wave-period amplification circuit and allowing the negative wave-period reference voltage generation circuit to be connected to the positive wave-period amplification circuit.