Patent ID: 9048657
Filing Date: 2015-06-02
Classification: H02H

Abstract:
1. A control circuit for an electric power circuit switch, the control circuit comprising: a sampling/hold circuit section configured to sample a period of a detection signal of a current of an electric power system and provide a sampled signal; a discrete Fourier transforming circuit section connected to the sampling/hold circuit section and perform a discrete Fourier transforming on the one-period sampled signal of the current of the electric power system provided from the sampling/hold circuit section to provide a magnitude and a phase of a frequency component of the current of the electric power system; a differentiator configured to differentiate the detection signal of the current of the electric power system to provide a rate of change of the current of the electric power system over time; and a controller connected to the discrete Fourier transforming circuit section and the differentiator and configured to determine whether to perform trip controlling according to the magnitude of the frequency component of the current of the electric power system from the discrete Fourier transforming circuit section or the rate of change from the differentiator on the basis of the rate of change of the current of the electric power system and the reference rate of change.