What is the difference between lightning arresters for power distribution and motors?

Lightning arrester manufacturers, European-style cable joints, cold-shrinkable cable terminals

The lightning arrester for the motor is mainly to prevent the overvoltage of the induction type power frequency operation. This overvoltage is often generated during the operation. For example, when the arc does not cross zero when the switch is opened, there will be an overvoltage when the circuit is opened. The loop impedance is different, and the operation overvoltage caused by the superposition of the voltage reflection wave is generated. These overvoltages are all power frequency overvoltages, that is, the frequency of the voltage waveform remains unchanged at 50HZ.

In addition to preventing operating overvoltages, lightning arresters for power distribution must also prevent atmospheric lightning overvoltages. This overvoltage waveform has a steep front end and a high frequency, but the subsequent current is small. The lightning arrester can discharge the peak value of the lightning wave to ensure The electrical appliances behind it are safe.

There are many types of arresters, including metal oxide arresters, line metal oxide arresters, gapless line metal oxide arresters, fully insulated composite jacket metal oxide arresters, and removable arresters.

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

Tube type arrester

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

Valve type arrester

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

Zinc oxide arrester

Zinc oxide lightning arrester is a lightning protection device with superior protection performance, light weight, pollution resistance and stable performance. It mainly uses the good non-linear volt-ampere characteristics of zinc oxide to make the current flowing through the arrester very small (microamp or milliampere level) at normal working voltage; when the overvoltage acts, the resistance drops sharply, venting the overvoltage Energy, to achieve the effect of protection. The difference between this kind of arrester and the traditional arrester is that it has no discharge gap and uses the non-linear characteristics of zinc oxide to discharge and break.

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