An Analog Low Pass Filter Design of RCD

Abstract

The residual current operated protective device (RCD) as a protection facility for the safe operation of the power grid, prevent personal electric shock casualties, and reduce fires, and so on. Currently, the RCD has maloperation, low operation rate and other problems. The reason, most of the RCDs cannot really identify the signal of the biologic shock branch. By the built RCD physical shock test system platforms, collected more than 1,000 groups of shock fault related electrical signals. Through the shock signal spectrum analysis, observed each harmonic variation law. According the signal characteristics of electric shock, selected 1kHz as the analog low pass filter cutoff frequency, using the design idea of Butterworth analog low pass filter calculate the transfer function, design the second-order low pass filter circuit to meet the filtering requirements. It is a foundation for the future analog filter circuit design of electric shock signal in intelligent detection board.