Classification of lightning arresters:
There are many types of lightning arresters, including metal oxide arresters, line-type metal oxide arresters, gapless line-type metal oxide arresters, fully insulated composite jacket metal oxide arresters, and detachable arresters. The main types of arresters include tube arresters, valve arresters and zinc oxide arresters. The main working principles of each type of lightning arrester are different, but their working essence is the same, which is to protect communication cables and communication equipment from damage.
Tube type arrester Tube type 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 being burned by the power frequency leakage current flowing through the pipe; the other is installed in the gas pipe, 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 aftercurrent. This is a protection gap type lightning arrester, which is mostly used for lightning protection on power supply lines.
Valve-type arrester The valve-type arrester consists of a spark gap and a valve resistor. The valve resistor is made of special silicon carbide. Chip resistors made of silicon carbide can effectively prevent lightning and high voltage and protect equipment. When there is high lightning voltage, the spark gap is broken down, the resistance value of the valve resistor decreases, and the lightning current is introduced into the earth, which protects cables or electrical equipment from the harm of lightning current. Under normal circumstances, the spark gap will not be broken down, and the resistance value of the valve resistor is relatively high, which will not affect the normal communication of the communication line.
Zinc oxide arrester Zinc oxide arrester is a kind of lightning protection equipment with superior protection performance, light weight, pollution resistance and stable performance. It mainly uses the good nonlinear volt-ampere characteristics of zinc oxide to make the current flowing through the arrester at normal operating voltage extremely small (microamperes or milliamperes); when overvoltage occurs, the resistance drops sharply and discharges the energy of the overvoltage to achieve the protection effect. The difference between this kind of arrester and traditional arrester is that it has no discharge gap and uses the nonlinear characteristics of zinc oxide to play the role of discharge and breaking.
Several types of lightning arresters have been introduced above. Each type of lightning arrester has its own advantages and characteristics and needs to be used in different environments to achieve good lightning protection effects.
Advantages of zinc oxide arrester:
1. The zinc oxide arrester has a large current flow capacity. This is mainly reflected in the ability of the arrester to absorb various lightning overvoltages, power frequency transient overvoltages, and operating overvoltages. The flow capacity of zinc oxide arresters produced by Chuantai fully meets or even exceeds the requirements of national standards. Indicators such as line discharge level, energy absorption capacity, 4/10 nanosecond high current impact tolerance, and 2ms square wave flow capacity have reached the domestic leading level.
2. Excellent protective properties of zinc oxide arresters Zinc oxide arresters are electrical products used to protect various electrical equipment in power systems from overvoltage damage and have good protective properties. Because the nonlinear volt-ampere characteristics of the zinc oxide valve are very good, only a few hundred microamps of current can pass through it under normal operating voltage, making it easy to design into a gapless structure, making it feature good protection performance, light weight, and small size. When overvoltage invades, the current flowing through the valve plate increases rapidly, which limits the amplitude of the overvoltage and releases the energy of the overvoltage. After that, the zinc oxide valve plate returns to the high resistance state, allowing the power system to operate normally.
3. The zinc oxide arrester has good sealing performance. The arrester element uses a high-quality composite jacket with good aging performance and good air tightness. Measures such as controlling the compression amount of the sealing ring and adding sealant are adopted. The ceramic jacket is used as a sealing material to ensure reliable sealing and stable performance of the arrester.
4. The mechanical properties of the zinc oxide arrester mainly consider the following three factors: ⑴ the earthquake force it withstands; ⑵ the maximum wind pressure acting on the arrester; ⑶ the top of the arrester bears the maximum allowable pulling force of the wire.
5. Good pollution-repelling performance of zinc oxide arresters. Gap-free zinc oxide arresters have high pollution resistance. The current creepage distance levels stipulated in national standards are: (1) Level II, moderately polluted areas: specific creepage distance 20mm/kv, (2) Level III, heavily polluted areas: specific creepage distance 25mm/kv, (3) Level IV, extremely polluted areas: specific creepage distance 31mm/kv.
6. High operational reliability of zinc oxide arresters. The long-term operational reliability depends on the quality of the product and whether the product selection is reasonable. There are mainly three aspects that affect its product quality: A. The rationality of the overall structure of the arrester; B. The volt-ampere characteristics and aging resistance characteristics of the zinc oxide valve plate; C. The sealing performance of the arrester.
7. Power frequency withstand capability Due to various reasons in the power system, such as single-phase grounding, long-line capacitance effect, and load shedding, the power frequency voltage will increase or a transient overvoltage with a high amplitude will occur. The arrester has the ability to withstand a certain power frequency voltage increase within a certain period of time.
