The structure and characteristics of common surge protectors:
May 23, 2022
The structure and characteristics of common surge protectors:
1>, open gap type
The working principle of the gap arrester: Based on the arc discharge technology, when the voltage between the electrodes reaches a certain level, the breakdown air arc will creep on the electrodes.
Advantages: strong discharge capacity, large flux (can reach 100KA), small leakage current
good thermal stability
Disadvantages: high residual pressure, slow response time, and continuous current
Process characteristics: Since the metal electrode bears a large current during discharge, it is easy to cause the sublimation of the metal, and the formation of a metal coating in the discharge chamber affects the start-up and normal use of the arrester. The production of discharge electrodes is mainly concentrated in some foreign arrester manufacturers, and the main component of the electrode is an alloy of tungsten metal.
Engineering application: The arrester of this structure is mainly used in the power supply system as a class B arrester. However, due to the reasons of the arrester itself, it is easy to cause a fire, and the arrester will be separated from the switchboard after the operation (flying out) and other accidents. According to the different models, it is suitable for various power distribution systems.
The installation distance must be considered when installing the project to avoid unnecessary losses and accidents.
2>, closed gap surge protector
Now there is a multi-layer graphite gap surge protector in the domestic market. This kind of surge protector mainly uses multi-layer gap continuous discharge, and each layer of discharge gap is insulated from each other. This laminated technology not only solves the problem of freewheeling The layer-by-layer discharge virtually increases the current capacity of the product itself.
Advantages: large discharge current test maximum 50KA (actual measured value) small leakage current
No freewheeling, no arc discharge, good thermal stability
Disadvantages: high residual pressure, slow response time
Process features: Graphite is the main material, and all copper cladding is used in the product to solve the problem of heat dissipation of the arrester during discharge, and there is no follow-up current problem. much lower.
Engineering application: This kind of surge protector is used in various B and C occasions, and it does not need to consider the arc problem compared with the open gap. Depending on the model, this product is suitable for various power distribution systems.
3>, discharge tube arrester
①Open discharge tube arrester
The open discharge tube arrester is essentially the same product as the open gap arrester, and both belong to the air arrester. But compared with the gap arrester, its current capacity is reduced by one level.
Advantages: small size, strong current capacity (10-15KA), small leakage current, no arc spray
Disadvantages: high residual pressure, poor consistency of freewheeling products, slow response time
②Closed gas discharge tube
The closed gas discharge tube is also called an inert gas discharge tube. It is mainly filled with inert gas. The discharge method is gas discharge. Generally, there are 2-pole and 3-pole structures. The appearance is similar to the picture above. Advantages: small volume (gas tube can be very small) large flow rate without arc
Disadvantages: poor product consistency (start-up voltage, residual voltage), high freewheeling residual voltage
Process characteristics: The air discharge tube is still an open product. It is not guaranteed that there will be absolutely no sparks ejected from the pressure discharge hole during operation. The gas discharge tube is a sealed structure. Generally, there are 2-pole and 3-pole structures. Thermal protection device (short-circuit device), when the temperature of the discharge tube exceeds a certain range, the short-circuit device is activated to make the discharge tube conduct as a whole. Prevent the high pressure in the discharge tube from causing the device to burst due to high temperature. Engineering application: General air discharge tubes are rarely used now, but gas discharge tubes are widely used in signal lightning arresters. Different models are also used on power arresters.
4>, zinc oxide resistance surge protector
①Single-chip varistor surge protector
The monolithic varistor surge protector was first invented and used by Japan in the 1980s. Until now, the utilization rate of monolithic varistor is also the highest among surge protectors. The working principle of the varistor surge protector is to use the nonlinear characteristics of the varistor. When the voltage does not fluctuate, the zinc oxide is in a high resistance state. When the voltage fluctuates and reaches the starting voltage of the varistor, the varistor quickly presents a low resistance state, limiting the voltage to a certain range.
②Multi-chip varistor surge protector
Because the flow rate of the single-chip varistor has not been ideal (generally the maximum discharge current of the single-chip varistor is 20KA8/20uS), under this premise, the multi-chip combined varistor surge protector is generated, and the multi-chip voltage The varistor combined surge protector mainly solves the problem that the flow rate of the single-chip varistor is small and cannot meet the use of B-level occasions. The generation of multi-chip varistor fundamentally solves the problem of varistor flux.
Advantages: large flow capacity, low residual pressure, fast response time (≤25ns),
No following current (freewheeling)
Disadvantages: large leakage current and fast aging. Thermally stable
Technological characteristics: Most of them use building block structures.
Engineering application: According to different structures, varistor surge protectors are widely used in class B, C, D and signal arresters. However, the problem that should be solved is that some products in the project have combustion phenomenon, so when selecting products, attention should be paid to the shell materials used by the manufacturer.
5>、Suppression diode lightning arrester
Suppression diode lightning protection products are mainly used in a large number of signal lightning protection products such as networks. The main devices used are P*KE (avalanche tube) and other products. The working principle is based on PN junction reverse breakdown protection.
Advantages: low residual pressure, high action accuracy, fast response time, no freewheeling, small volume
Disadvantages: small flux 2.5 varistor/gas discharge tube combination
①Simple combination arrester
The typical structure of the combined arrester is the N-PE structure. Compared with the arrester with a single structure, this arrester combines the advantages of two different products and reduces the shortcomings of a single device.
Advantages: large flux and fast response time
Disadvantages: relatively high residual pressure
Engineering application: lightning arrester only used in N-PE system, suitable for use in areas with large voltage fluctuations.
②Complex combined arrester
This arrester gives full play to the advantages of various components, and generally uses a large number of varistors and gas discharge tubes in structure. The arrester of this structure generally has a high flow capacity and a low residual pressure. The arrester with this structure is also called an integrated arrester in the industry.
Advantages: large flow rate, fast response time, low residual pressure, no freewheeling, good thermal stability
Cons: No sound alarm, no counter
Technological characteristics: The circuit structure of the integrated arrester is compact, which fully utilizes the characteristics of fast response time of zinc oxide resistance, and combines the advantages of gas discharge tube with high flow capacity. In the circuit, the arrester uses more zinc oxide resistors to improve the flow capacity of the overall arrester, and uses a gas discharge tube as a backup discharge channel. Based on this perfect circuit structure, the service life of the arrester is greatly improved.
The integrated arrester is widely used in various installation environments of B, C, and D according to different models. Because it is an integrated design, it is more suitable for use in occasions where there is no installation distance. (IEC stipulates that the shortest distance between the three levels of B, C, D modular arresters is more than 10M)
6>, silicon carbide arrester (valve arrester)
Silicon carbide arresters are mainly used in high-voltage power lightning protection, and are still the most widely used power lightning protection products in power systems today.