Detection device for multi-point earthing fault of small bus N600

Abstract

The invention discloses a detection device for multi-point earthing fault of a small bus N600. The detection device is composed of a constant-current signal generator (A), a signal sampler (B) and a signal analyzer (C) which are connected in the electric loop manner. The constant-current signal generator (A) generates square signals of 5mA, 20mA, 100mA and 200mA and injects the same into the small bus N600; the signal sampler (B) receives and samples the square signals of 5mA, 20mA, 100mA and 200mA which are generated from the constant-current generator (A) and send the same to the signal analyzer (C) to judge whether or not the multi-point earthing fault occurs. The detection device has the advantages that synchronizing signal current measurement is adopted, earthing correctness of the earthing loop N600 is determined through judgment of two currents, thus earthing correctness and validity of the loop N600 of the transformer substation is effectively detected during operation, various interference signals are prevented, judgment is accurate, false alarm is avoided, and earthing fault is eliminated.

Description

technical field [0001] The invention relates to the field of power system detection equipment, in particular to a N600 multi-point ground fault detection device for a PT secondary public circuit used for substation relay protection. Background technique [0002] The wiring of the relay protection device is complicated. The secondary circuit of the PT is from the outdoor PT site to the control room, and the terminal box to the protection screen. There are many lines and long wires. The zero line in the control room is called the N600 small bus. The electric power industry and the State Grid "Power System Relay Protection Anti-accident Measures" clearly stipulate that the secondary circuits of several groups of voltage transformers connected through the control room zero-phase small bus N600, Only one point in the control room should be grounded. If there is a multi-point ground fault, in severe cases, the relay protection device and the safety automatic device will not operat...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide an N600 multi-point ground fault detection device, which can make an accurate judgment on the single-point grounding of the PT secondary public circuit for relay protection in substations, and solve the problem of whether there is multi-point grounding in the N600 line of the substation

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