A Leakage Protection Circuit with Power Supply Monitoring Function

Abstract

Disclosed is an electric leakage protection circuit with a power supply monitoring function. The electric leakage protection circuit comprises an electric leakage protection circuit, a power supply monitoring circuit and a power supply circuit, wherein the electric leakage protection circuit is used for monitoring an electric leakage fault on a power supply line, and disconnecting an electric loadwhen the electric leakage fault reaches or is higher than a set electric leakage protection threshold value; the input end of the power supply monitoring circuit is connected to the output end of thepower supply circuit, and the power supply monitoring circuit is used for monitoring the power supply of the electric leakage protection circuit, and outputting an action or an alarm signal when thepower supply voltage of the electric leakage protection control circuit is monitored to be lower than a set threshold value; and the input end of the power supply circuit is connected to a phase lineand a neutral line while the output end is connected to the electric leakage protection circuit and the power supply monitoring circuit, and the power supply circuit is used for providing a power supply for the electric leakage protection circuit. According to the electric leakage protection circuit, by detecting the voltage change on the power supply circuit, the fault of a diode switch in the power supply circuit can be detected, so that the safety of the electric leakage protection circuit is improved.

Description

technical field [0001] The invention relates to a leakage protection circuit, in particular to a leakage protection circuit with a power supply monitoring function. Background technique [0002] In the power supply system, in order to deal with the safety issues of human body electric shock caused by line aging and faults at the load end, it is usually necessary to install a residual current protection circuit breaker with leakage protection function at the node connected to the load. This circuit breaker judges whether a leakage fault occurs by detecting the vector sum of the phase line current and the neutral line current through the zero-sequence current transformer. When the detected leakage current is greater than the set threshold, the circuit breaker trips its internal mechanical device, disconnects the power supply of the load, and protects the safety of people and equipment. [0003] In order to verify the working status of the residual current protection circuit b...

AI Technical Summary

Problems solved by technology

The fault cannot be found even if the self-test is carried out in the negative half cycle

However, when a normal leakage occurs, although the leakage protection control circuit can turn on Q1, the current on the tripping coil needs to return to the neutral line through the path formed by Q0 and R2 to form a closed loop. Due to the current limiting effect of the R2 resistor, The current flowing through the tripping coil is only tens of milliamps, which cannot make the tripper operate, and the circuit breaker cannot disconnect the load

The function of the circuit breaker fails, but the self-inspection control circuit cannot detect the fault and send out an alarm signal

It can be seen that there are serious security risks in the existing scheme

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