1) It is used to protect electrical equipment from high transient over-voltage and limit the freewheeling time and the freewheeling amplitude. This term includes any external clearance necessary for the normal function of the appliance during operation and installation, regardless of whether it is a part of the whole. Note 1: The lightning arrester is usually connected between the grid conductor and the ground wire, but sometimes it is also connected near the electrical winding or between the conductors. Note 2: Lightning arrester is sometimes called overvoltage protector or overvoltage limiter. 2) Arrester is another important equipment often used to prevent communication cables from being damaged by lightning. The following describes the relevant knowledge of lightning arrester. definition Arrester: an electrical appliance used to protect electrical equipment from the harm of high transient overvoltage during lightning stroke, and to limit the freewheeling time and the freewheeling amplitude. Lightning arrester is sometimes called overvoltage protector or overvoltage limiter. Applied discipline: information communication Features: High transient, overvoltage, electrical appliances, lightning protection Scope of application AC gapless metal oxide arrester is used to protect the insulation of AC power transmission and transformation equipment from lightning overvoltage and switching overvoltage. It is applicable to overvoltage protection of transformers, transmission lines, distribution panels, switch cabinets, power metering boxes, vacuum switches, parallel compensation capacitors, rotating motors and semiconductor devices. Features and principles AC gapless metal oxide surge arresters have excellent nonlinear volt ampere characteristics, good response characteristics, no freewheeling, large current capacity, low residual voltage, strong ability to suppress overvoltage, pollution resistance, anti-aging, free from altitude constraints, simple structure, gapless, tight sealing, long life and other characteristics. Under normal system working voltage, the arrester presents a high resistance state, and only microamp current passes through. Under the action of over-voltage and large current, it presents low resistance, thus limiting the residual voltage at both ends of the arrester. classification There are many types of surge arresters, including metal oxide surge arresters, line type metal oxide surge arresters, gapless line type metal oxide surge arresters, fully insulated composite sheathed metal oxide surge arresters, and removable surge arresters. The main types of lightning arresters are pipe type, valve type and zinc oxide type. The main working principle of each type of lightning arrester is different, but their work essence is the same, which is to protect communication cables and communication equipment from damage. Tubular arrester The tubular arrester is actually a protective gap with high arc extinguishing capacity. It is composed 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 pipe from being burned by the power frequency leakage current flowing through the pipe; The other one is installed in the gas pipe, which is called internal gap or arc extinguishing gap. The arc extinguishing capacity of tubular arrester is related to the power frequency continuous current. This is a kind of protective gap type arrester, which is mostly used for lightning protection on power supply lines. Valve type arrester Valve type arrester is composed of spark gap and valve resistance, which is made of special silicon carbide. The valve resistance made of silicon carbide can effectively prevent lightning and high voltage and protect the equipment. When there is high lightning voltage, the spark gap is broken down, the resistance value of the valve resistance drops, and the lightning current is introduced to the ground, which protects the cable or electrical equipment from the harm of lightning current. Under normal conditions, the spark gap will not be broken down, and the resistance value of the valve blade resistance is high, which will not affect the normal communication of the communication line. Zinc oxide arrester Zinc oxide arrester is a lightning protection equipment with superior protection performance, light weight, pollution resistance and stable performance. It mainly makes use of the good nonlinear volt ampere characteristics of zinc oxide to make the current flowing through the arrester very small (micro ampere or milliampere level) under normal working voltage; When over-voltage acts, the resistance drops sharply, and the over-voltage energy is released to achieve the protection effect. 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 disch
