Leakage protector principle

LC03-3.3 SOP8 TVS Static Protection 3.3V

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Guide: "Electricity" brings convenience to human beings, and it also brings disasters to human beings. Since the invention of electricity, various electrical accidents such as electric appliances burning, causing fires, causing electric shock and death have come one after another. Therefore, leakage protectors should be transported. Born, playing the role of Altman, defeated all kinds of little monsters called "electrical accidents", how did Altman hit the little monsters? Let us look at it~~

First, the principle of leakage protector - - Introduction

Leakage protector , also known as leakage switch and leakage circuit breaker, is a kind of protection device used to prevent electric shock and electrical fire when circuit or electrical insulation is damaged, and short circuit to ground, generally installed in each distribution box. The power supply line on the socket circuit and the total distribution box of the whole building. It can be used to protect the line or motor from overload and short circuit, and can also be used for infrequent conversion start of the line under normal conditions.

Second, the principle of leakage protector - - classification

The leakage protector can be divided into three types: leakage protection relay, leakage protection switch and leakage protection socket according to the protection function and use. Among them, the leakage protection relay refers to a leakage protection device that has a function of detecting and judging leakage current, but does not have a function of turning on or off the main circuit. The leakage protection switch refers to a leakage protection device that has a function of detecting and judging leakage current and also has a function of turning on and off the main circuit. The leakage protection socket refers to a power socket that has a function of detecting and judging leakage current and cutting off the circuit.

Third, the principle of leakage protector - - structure

The current-type leakage protector uses the residual current in the circuit as the action signal, and the electronic component as the intermediate mechanism. It has high sensitivity and complete functions. It has now dominated the leakage protector market at home and abroad. Below we use current-type leakage protection. The device is taken as an example to introduce the structure of the leakage protector.

The current type leakage protector is mainly composed of four parts: a detecting element, an intermediate link, an actuator, and a test device. The detecting component is equivalent to a zero-sequence current transformer, and the induced electromotive force is sent to the intermediate link for processing during leakage; the intermediate link is generally composed of an amplifier, a comparator and a trip unit for amplifying the leakage signal and sending it To the actuator; the actuator is used to receive the instructions of the intermediate link, the action occurs, and the power supply at the fault is cut off; the test device is used for periodic inspection of the leakage protector to check whether it can operate normally.

Fourth, the principle of leakage protector

Under normal circumstances, the three-phase load current is substantially in equilibrium with the ground leakage current, and the phasor of the primary coil current flowing through the transformer is about zero, that is, the total magnetic flux generated by the iron core is zero, and the zero-sequence transformer The secondary coil has no output.

When an electric shock occurs, the electric current flows through the earth to form a loop, and a zero-sequence current is generated. The zero-sequence current does not flow back through the primary coil of the transformer, thereby breaking the balance, so that there is a zero-sequence flux in the iron core, and the transformer The secondary coil has an output signal. This signal is amplified and compared to the component. If the predetermined action value is reached, the execution signal is sent to the actuator to trip and the power is turned off.

Leakage protector principle