The lightning arrester is usually connected between the live conductor and the ground and in parallel with the protected equipment. When the overvoltage value reaches the specified operating voltage, the arrester will act immediately to make the charge flow, limit the overvoltage amplitude and protect the equipment insulation; After the voltage value is normal, the lightning arrester quickly recovers to ensure the normal power supply of the system.
There are two types of lightning arresters: tube type and valve type. Valve arrester is divided into silicon carbide arrester and metal oxide arrester (also known as zinc oxide arrester). Tube arrester is mainly used for incoming line protection and weak line insulation protection in substations and power plants.
Silicon carbide arrester is widely used in AC and DC systems to protect the insulation of power generation and substation equipment. Zinc oxide arrester is gradually replacing silicon carbide arrester because of its better protection performance. Widely used in AC and DC systems to protect the insulation of power generation and transformation equipment, especially suitable for power grids with effective neutral grounding 1 10 kV and above.
Extended data:
Lightning arrester characteristics:
First, the current capacity of zinc oxide arrester is large.
This is mainly reflected in the ability of lightning arrester to absorb various lightning overvoltage, power frequency transient overvoltage and operating overvoltage. The current capacity of zinc oxide arrester produced by Chuantai completely meets or even exceeds the requirements of national standards. The line discharge level, energy absorption capacity, 4/ 10 nanosecond heavy current impulse tolerance, 2ms square wave current capacity and other indicators have reached the domestic leading level.
Second, the protective characteristics of zinc oxide arrester are excellent.
Zinc oxide arrester is an electrical product used to protect all kinds of electrical equipment in power system from overvoltage damage, which has good protection performance.
Because the nonlinear volt-ampere characteristics of zinc oxide valve plate are very good, only a few hundred microamperes of current flow under normal working voltage, which is convenient to design into a gapless structure, making it have the characteristics of good protection, light weight and small volume.
When overvoltage invades, the current flowing through the valve plate increases rapidly, and at the same time, the amplitude of overvoltage is limited and the energy of overvoltage is released. After that, the zinc oxide valve plate returns to the high resistance state, so that the power system can work normally.
Thirdly, the zinc oxide arrester has good sealing performance.
The arrester element adopts high-quality composite sheath with good aging performance and air tightness, and adopts measures such as controlling the compression of sealing ring and adding sealant, and adopts ceramic sheath as sealing material to ensure reliable sealing and stable performance of arrester.