Necessary for weak electricians: knowledge of leakage protection switch

Leakage current action protector, referred to as leakage protector, also called leakage protection switch, is mainly used to protect the equipment from electric leakage and protection against fatal danger. According to the working principle of the protector, it can be divided into three types: voltage type, current type and pulse type.
The voltage type protector is connected between the neutral point of the transformer and the earth. When an electric shock occurs, the neutral point shifts to generate voltage to the ground, so that the protection action cuts off the power supply, but since it protects the entire distribution low voltage network, It can't be graded, so the power outage is large and the action is frequent, so it has been eliminated.
The pulse type current protector is an abrupt change in the phase and amplitude of the three-phase unbalanced leakage current when an electric shock occurs, and is used as an action signal, but also has a dead zone.
The current-type leakage protector is a part of the zero-sequence current in the circuit (usually called residual current) as the action signal, and the electronic component is used as the intermediate mechanism. The sensitivity is high and the function is complete. Therefore, the protection device is more and more widely used. Applications.
How to connect the circuit breaker and leakage switch to the physical map
The leakage circuit breaker is divided into single-phase line and three-phase line. Single-phase wiring is divided into four groups of wiring methods and multiple groups of wiring methods. Look exactly right. As for the use of the C60 leakage circuit breaker can fully meet the above electrical appliances. C60 rated current range: 1A-63A. P = UI = 220V * 63A = 13860W. The total power of all the above appliances will not exceed the rated power of the leakage circuit breaker, so the use is safe. The following is the wiring diagram of the leakage circuit breaker for reference:




The operating principle of the leakage protection switch is:
There are two groups on one core: one input current winding and one output current winding. When there is no leakage, the input current and the output current are equal. The vector sum of the two fluxes on the core is zero, it will not be in the first The potential is induced on the three windings, otherwise the induced voltage is formed on the third winding, and the actuator is pushed up to cause the switch to trip. When the leakage protection switch works normally, there is no leakage current in the circuit except the working current through the leakage protector. At this time, the current flowing through the zero-sequence transformer (detecting the transformer) is equal, the direction is opposite, the sum is zero, and the transformer core is in the core. The induced flux is also equal to zero, the secondary winding has no output, the automatic switch remains in the on state, and the leakage protector is in normal operation. When the protected electrical equipment and the line are leaking or someone is getting electric shock, there is a ground fault current, so that the current flowing through the detecting transformer is not zero, the magnetic flux is induced in the transformer core, and the secondary winding has induction. The generation of current is amplified and output, so that the operation of the leakage release device pushes the automatic switch to trip to achieve the purpose of leakage protection.
The leakage protector, commonly known as the leakage switch, can not only protect the personal safety, but also supervise the insulation of the low-voltage system or equipment. But don't think that after installing the leakage protector, you can be foolproof and should be precautionary (because it is only an additional protection in the basic protection measures). Only by understanding the role of the leakage protector and correctly using the leakage protector is the fundamental guarantee for achieving safe use of electricity.
The following items should be noted during the use of the leakage protection switch:
1. After the leakage protection switch is put into operation, it should consciously establish an operation record and improve the corresponding management system;
2. After the leakage protection switch is put into operation, under the power-on state, press the test button once or twice a month to check whether the leakage protection switch is normal and reliable, especially in the thunderstorm season.
3. Regularly analyze the operation of the leakage protection switch and replace the faulty leakage protection switch in time;
4. The maintenance of the leakage protection switch should be carried out by professionals. If there is any abnormality during operation, it should be handled by an electrician to avoid expanding the scope of the accident;
5, after thunderstorm or other unexplained reasons to make the leakage protection switch action, should be checked and analyzed;
6. After the leakage protection switch is operated, if the cause of the accident is not found after inspection, the test is allowed to be closed once. If it is operated again, the cause should be identified, the fault should be found, and if necessary, the action characteristic test should be carried out, and the power transmission should not be forced continuously. Except that it is confirmed by the inspection that the leakage protection switch itself has failed, it is strictly forbidden to remove the leakage protection switch forcibly sending power;
7. Before the leakage protection switch of the exiting operation is used again, the action characteristic test shall be carried out according to the items specified by the relevant department;
8. The operating characteristics of the leakage protection switch are set by the manufacturer and used according to the product manual.
9. After an accidental electric shock accident occurs within the protection range of the leakage protection switch, the operation of the leakage protection switch should be checked, and the reason for failing to protect the function should be analyzed. The site should be protected before the investigation, and the leakage protection should not be removed. switch;
10. In order to check the operating characteristics and changes of the leakage protection switch during operation, the operational characteristics test should be performed periodically. The characteristic test items include: testing the leakage current value, testing the leakage current value, and testing the breaking time;
11. When the leakage protection switch is tested for operational characteristics, special test instruments that have passed the test of relevant national departments shall be used. It is strictly forbidden to use the test method of direct contact with the grounding device.
12. In addition to the periodic test of the leakage protection switch, the leakage protection switch should be regularly checked and maintained according to the requirements of the low-voltage electrical equipment.
13. The line after the installation point of the leakage protector should be insulated from the ground. If the insulation to the ground is reduced and the leakage current exceeds a certain value (usually around 15 mA), the protector will operate and cut off the power. Therefore, it is required that the ground insulation of the line must be good, otherwise it will often cause malfunction and affect normal power consumption.
14. Lighting and other single-phase power loads should be evenly distributed to the three-phase power line. When the deviation is large, adjustment should be made to make the leakage currents of each phase approximately equal; when the low-voltage line is buried, the length of the three phases should be similar.
15. After each action of the leakage protector, immediately identify the cause, and then re-invest and resume power transmission after the fault is removed. It is strictly forbidden to forcibly electrify, and it is not allowed to be taken out of operation to ensure safe use of electricity.
16. The leakage protector is the user's asset. The user should strengthen the management and routine maintenance during the use of the leakage protector, and test it regularly. Press the test button every month under the power-on state to check whether the action is reliable, to ensure that it is intact and found The problem should be dealt with in a timely manner, and it cannot be replaced in time.
17. The leakage protector should be installed in a dry place to avoid the erosion of rain, dust and harmful gases. It can be installed in the same meter box as the electricity meter and fuse box. The leakage protector should be installed under the fuse box. The wiring should not be reversed or reversed, and should be installed vertically. The pressure line nut should be tightened.
18, the leakage protector is installed and checked without errors, and the test button is checked for normal operation before it can be put into use.
19. In places with high humidity, high temperature, large metal occupation coefficient and other well-conducted places, an independent leakage protector must be installed. Do not use one leakage protector to protect more than two devices (or tools) at the same time.
The above-mentioned several precautions are very easy to make mistakes in use, so it is specially proposed in this article, I hope the reader pays special attention when using the leakage protector.

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