Research on the Principle of Residual Current Protection Technology Based on Transient Waveform Criterion

Xiao Guolei,Jiang Feng,Wu Binfeng,Lv Chengcong,Song Yan,Jin Weidong,Ye Juwei,H Li,G Vilardi

doi:10.1051/e3sconf/202020402009

Abstract

The paper uses a magnetic modulation current transformer method to detect transient waveform residual currents containing pulsating DC components and even smooth DC components. At the same time, it uses IIR-based digital low-pass filters to filter the collected signals, which improves Filtering accuracy. The software design is based on the floating-point DSP-TMS320F28335, which realizes the accurate sampling and analysis of the transient waveform residual current, and the transient waveform residual current detection meets the standard requirements.

Highlights

With the increase in the number and types of electrical equipment, the number and forms of equipment leakage faults continue to increase
Various types of residual current protection appliances can only act on the corresponding residual current: AC type residual current protection appliances can only operate correctly when AC residual current; Type A can operate correctly on AC residual current and pulsating DC residual current; Type F can operate correctly on both AC residual current and pulsating DC residual current and can detect 1000Hz leakage signal at the same time; Type B can operate correctly for AC residual current and pulsating DC residual current, and for smooth DC residual current
The transient waveform as the criterion refers to that the current flowing through the human body is a non-sinusoidal, non-linear current waveform

Summary

Introduction

With the increase in the number and types of electrical equipment, the number and forms of equipment leakage faults continue to increase. Human body contact current in a short time (about 2 to 3 cycles), the skin impedance is a time-varying network, its resistance value changes from large to small, and later transformed into a time-invariant network. In addition to transient waveform protection, the residual current operated protector based on the transient waveform criterion will have multiple protection functions such as automatic tracking, overcurrent, and residual current. It can be designed as an integrated type, multiple functions, and small size. Intelligent, the main circuit current can be set leakage circuit breaker

Residual current detection method

Working principle of direct measurement Hall current sensor

Digital sampling filter algorithm

Technical principle realization

Experimental test

Conclusion