Leakage switch principle

Photocoupler

Introduction: When it comes to leakage switches , unfamiliar partners may mistake them for switches that leak electricity. This is actually not the case. What we need in our daily life is not the leakage switch, but the switch to prevent leakage. When the switch is automatically disconnected and the switch can detect leakage, let us explain the leakage switch of this non- leakage switch in detail~

First, the principle of leakage switch - - Introduction

Leakage switch, the English name is The leakage switch, which is a device that can automatically open the switch under the condition of leakage to protect people from the leakage current. The leakage switch is mainly composed of a primary winding (including two windings of the output current winding and the input current winding), a secondary winding and an iron core connected between the two windings. Under normal circumstances, the output current is equal in size to the input circuit, and the direction is opposite. The magnetic flux generated on the iron core also cancels each other, and the vector sum is zero, and no induced electromotive force is generated. In the case of leakage current, the input and output generate a current difference, and the generated magnetic flux vector and non-zero are generated twice. An induced electromotive force is generated across the windings that acts on the actuator to open the switch.

Second, the principle of leakage switch

Leakage protector is a very important application of leakage switch. Let's take the leakage protector as an example to describe the principle of leakage switch. The schematic diagram of the leakage protector is as follows. When there is no leakage current, the currents at both ends of the zero-sequence current transformer are equal in magnitude and opposite in direction. No induced magnetic flux is generated in the core, and there is no current output at the secondary winding end. The switch is always kept closed; when it is in an abnormal state, when there is leakage, the current across the zero-sequence current transformer is not equal, a current difference is generated, and an induced magnetic flux is generated in the iron core, and then in the second The winding end generates an output current, and after the current is amplified, the electromagnetic release device is pushed to make the switch switch to the off state.

Third, leakage switch principle - - classification

The leakage protector can be divided into two types: an electronic leakage protector and an electromagnetic leakage protector according to the different actuators of the tripping action. Wherein, the actuator of the electronic leakage protector is a relay, and the method of using the relay to open and close the switch has the characteristics of high sensitivity, low cost, small error, etc., and the actuator of the electromagnetic leakage protector is an electromagnetic release, using The electromagnetic tripping device has the advantages of strong anti-interference and stable leakage characteristics, but the cost is relatively high.

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