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The principle and function of arrester
Source: | Author:lurensi | Published time: 2022-03-19 | 60 Views | Share:

Scope of application

AC gapless metal oxide arresters are used to protect the insulation of AC power transmission and transformation equipment from lightning overvoltage and operating overvoltage damage. It is suitable for overvoltage protection of transformers, transmission lines, distribution panels, switch cabinets, power metering boxes, vacuum switches, parallel compensation capacitors, rotating electrical machines and semiconductor devices.

Features and Principles

AC gapless metal oxide arrester has excellent nonlinear volt-ampere characteristics, good response characteristics, no freewheeling, large current capacity, low residual voltage, strong ability to suppress overvoltage, anti-pollution, anti-aging, not subject to altitude constraints, Simple structure, no gap, tight seal, long life and so on.

The arrester is in a high resistance state under normal system operating voltage, and only microampere current flows. It exhibits low resistance under the action of overvoltage and high current, thus limiting the residual voltage across the arrester

Classification

There are many kinds of arresters, including metal oxide arresters, line-type metal oxide arresters, gapless line-type metal oxide arresters, fully insulated composite jacketed metal oxide arresters, and detachable arresters.

The main types of arresters are tubular arresters, valve arresters and zinc oxide arresters. The main working principle of each type of arrester is different, but their work is essentially the same, all to protect communication cables and communication equipment from damage.

Tubular arrester

The tubular arrester is actually a protection gap with high arc extinguishing ability. It consists of two series gaps. One gap is in the atmosphere, which is called the outer gap. Its task is to isolate the working voltage and prevent the gas production tube from flowing through the tube. The other is installed in the gas pipe, which is called the inner gap or arc extinguishing gap. The arc extinguishing ability of the tubular arrester is related to the size of the power frequency freewheeling. This is a protective gap type arrester, which is mostly used for lightning protection on power supply lines.

valve arrester

The valve arrester is composed of spark gap and valve plate resistance. The material of valve plate resistance is special silicon carbide. The valve plate resistor made of silicon carbide can effectively prevent lightning and high voltage, and protect the equipment. When there is a high voltage of lightning, the spark gap is broken down, the resistance value of the valve plate resistor drops, and the lightning current is introduced into the ground, which protects the cable or electrical equipment from the damage of the lightning current. Under normal circumstances, the spark gap will not be broken down, and the resistance value of the valve plate resistor is high, which will not affect the normal communication of the communication line.

Zinc oxide arrester

Zinc oxide arrester is a lightning arrester with superior protection performance, light weight, pollution resistance and stable performance. It mainly uses the good nonlinear volt-ampere characteristics of zinc oxide, so that the current flowing through the arrester is extremely small (micro-amp or milli-amp level) under normal working voltage; when over-voltage acts, the resistance drops sharply, discharging the over-voltage energy for protection. The difference between this arrester and the traditional arrester is that it has no discharge gap, and uses the nonlinear characteristics of zinc oxide to play the role of leakage and interruption.

effect

The arrester is connected between the cable and the ground, usually in parallel with the protected equipment. The arrester can effectively protect the communication equipment. Once an abnormal voltage occurs, the arrester will act and play a protective role. When the communication cable or equipment is running under normal working voltage, the arrester will not work, and it is regarded as an open circuit to the ground. Once a high voltage occurs and the insulation of the protected equipment is endangered, the arrester will act immediately to guide the high-voltage surge current to the ground, thereby limiting the voltage amplitude and protecting the insulation of communication cables and equipment. When the overvoltage disappears, the arrester quickly returns to its original state, so that the communication line can work normally.

Therefore, the main function of the arrester is to cut the invading flow wave and reduce the overvoltage value of the protected equipment through the function of the parallel discharge gap or the nonlinear resistor, thereby protecting the communication line and equipment.

Lightning arresters can be used not only to protect against high voltages generated by lightning, but also to protect against operating high voltages.

The role of the arrester is to protect various electrical equipment in the power system from lightning.

An electrical appliance damaged by voltage, operating overvoltage, and power frequency transient overvoltage impact. The main types of arresters are protective gap, valve arrester and zinc oxide arrester. The protection gap is mainly used to limit the atmospheric overvoltage, and is generally used for the protection of the incoming line section of the power distribution system, lines and substations. Valve type arrester and zinc oxide arrester are used for the protection of substations and power plants. In systems of 500KV and below, they are mainly used to limit atmospheric overvoltage. In ultra-high voltage systems, they will also be used to limit internal overvoltage or for internal overvoltage. Backup protection.