Creepage circuit breaker

Abstract

The leakage circuit breaker includes: a zero-phase current transformer (3), which detects the leakage current of the multi-phase AC circuit (1); a leakage detection circuit (4); Open the contact of the AC circuit (1); the test circuit (6) feeds the test current (It) of the simulated leakage through the conduction test switch (6a); the filtering and amplification unit (10) is arranged on the zero-phase current transformer (3 ) and the leakage detection circuit (4), including an operational amplifier (10a) as an amplifying element to amplify the secondary side output of the zero-phase current transformer (3) at an amplification level corresponding to the setting value of the sensitivity setting unit (11) Current (Is). In the earth leakage circuit breaker, an active filter circuit including an operational amplifier (10a) is contained in a filter and amplifying unit (10). During the test, the active filter circuit is switched from a low-pass filter circuit to a band-pass circuit to remove noise and offset components that cause test failures.

Description

technical field [0001] The present invention relates to a leakage circuit breaker used to detect leakage in a power distribution system, so as to prevent leakage accidents before they occur, in particular to a leakage circuit breaker provided with a test circuit for determining the function of leakage tripping. Background technique [0002] It is well known that an earth leakage circuit breaker is provided with a test circuit for confirming the operation of the earth leakage tripping function (see Patent Document 1, for example). Figure 4 is a block diagram of the circuit disclosed in Patent Document 1, which shows an example circuit of the relevant earth leakage circuit breaker provided with the test circuit. [0003] exist Figure 4 In, reference numerals 1, 2 and 3 respectively denote a three-phase alternating current (AC) circuit, a main circuit switch contact device for switching the AC circuit 1, and detecting a leakage current in the AC circuit 1 by using the AC circu...

AI Technical Summary

Problems solved by technology

This problem is that the magnitude of the output circuit Is fed from the secondary side of the zero-phase current transformer 3 to the leakage detection circuit 4 is insufficient (too small) to be smaller than the threshold value set by the leakage detection circuit 4, which hinders the normal function of the leakage test operate

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