Single-phase ground fault positioning method for ground protective device of low-current system

Abstract

The invention discloses a single-phase ground fault positioning method for a ground protective device of a low-current system, which does not affect the protective performance of the ground protective device and can quickly find out a ground fault point. The method comprises the following steps that: a microcomputer intelligent controller judges whether a system is grounded or has a grounded phase difference or not according to the changes of a system line, a phase voltage and a zero sequence voltage; and when a single-phase ground fault happens, the microcomputer intelligent controller sendsa switching command to a grounded phase breaker. The method is characterized in that: after being switched on, the grounded phase breaker is connected with a grounding network through a low-impedancecurrent limiting reactor with a secondary coil; at the time, a grounding current of the system flows through a primary coil of the low-impedance current limiting reactor, and after the current is detected, the microcomputer intelligent controller gets into work with a high frequency signal generator connected with the secondary coil of the low-impedance current limiting reactor to inject a high frequency current into the system; and a handheld high frequency signal receiver moves along a fault line for searching the fault point, and the corresponding point where the received signal gradually becomes weak when the handheld high frequency signal receiver departs from some point is the ground fault point.

Description

technical field [0001] The invention relates to a single-phase grounding fault location method of a small current system grounding protection device. Background technique [0002] The grounding protection device of the small current system quickly protects the single-phase grounding fault point without arcing, resulting in no trace of the grounding fault point, and the inspectors cannot accurately judge the fault point. In order to solve this problem, a voltage transformer is currently used to inject a high-frequency current signal into the fault circuit, and then a handheld high-frequency signal receiver is used to move along the grounding line and locate the fault point according to the strength of the received high-frequency signal. This method is affected by the low-impedance shunt of the grounding protection device, so that the injected high-frequency current signal flows into the fault line with a weak component, resulting in extremely low detection sensitivity, and it...

AI Technical Summary

Problems solved by technology

This method is affected by the low-impedance shunt of the grounding protection device, so that the injected high-frequency current signal flows into the fault line with a weak component, resulting in extremely low detection sensitivity, and it is still impossible to accurately locate the fault point

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