Electric leakage detection protective circuit having precise overload protection function

Abstract

The present invention provides an electric leakage detection protective circuit having a precise overload protection function. The electric leakage detection protective circuit comprises an input terminus of a power supply, an output terminal of the power supply, a major loop switch, an electric leakage induction coil, an electric leakage control chip, a thyristor and an electromagnetic trip coil, and also comprises an overload protection circuit. The overload protection circuit includes a sampling resistor, a linear amplification circuit and a voltage comparison circuit, wherein the voltage comparison circuit is configured to compare a voltage signal after amplification of the linear amplification circuit with a preset voltage value and output a high level to drive the conduction of the thyristor so as to allow the electromagnetic trip coil to form a pathway when the voltage signal exceeds the voltage signal. According to the invention, the voltage signal on the sampling resistor after amplification of the linear amplification circuit is compared with a preset voltage value, an overcurrent occurs when the voltage signal on the sampling resistor exceeds the preset voltage value, and a major loop switch is immediately switched off. The electric leakage detection protective circuit having a precise overload protection function has high detection precision, sensitive reaction, simple and reasonable circuit design, small elements and low cost.

Description

technical field [0001] The invention relates to the field of leakage protection, in particular to a leakage detection and protection circuit with precise overload protection function. Background technique [0002] The current leakage protection circuit generally includes a power input terminal, a power output terminal, a main circuit switch, a leakage induction coil, a leakage control chip, a thyristor and a path formed when the thyristor is turned on to drive the main circuit switch to trip and disconnect. Electromagnetic trip coil, etc., when there is a leakage current in the circuit, the leakage induction coil sends the leakage current signal to the leakage control chip, and the leakage control chip drives the thyristor to conduct, thereby making the electromagnetic trip coil form a path, driven by the magnetic field The internal iron core acts, thereby driving the main circuit switch to trip and disconnect. This type of circuit usually only has the leakage protection fu...

AI Technical Summary

Problems solved by technology

This type of circuit usually only has the leakage protection function. If it is necessary to provide the overload protection function (the magnitude of the overload current is much greater than the rated current, and the leakage protection function can no longer satisfy the user's consideration of preventing electric shock and preventing fire caused by overload for safe use of electricity) often By setting a mechanical switch such as a thermal bimetal, the main circuit is disconnected through the heat deformation of the mechanical element

This kind of overload protection structure has low sensitivity and slow response, so there are still theoretical safety hazards

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