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Zinc oxide arrester is an arrester with good protection performance. Utilizing the good nonlinear volt-ampere characteristics of zinc oxide, the current flowing through the arrester at normal operating voltage is extremely small (microamperes or milliamperes); when overvoltage occurs, the resistance drops sharply and the energy of the overvoltage is discharged. achieve protective effects. The difference between this kind of 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 discharge and breaking. Zinc oxide arrester is a new type of arrester developed in the 1970s. It is mainly composed of zinc oxide varistor. Each piece of varistor has a certain switching voltage (called varistor voltage) when it is made. Under normal working voltage (that is, less than the varistor voltage) the varistor value is very large, which is equivalent to the insulation state, but under Under the action of impulse voltage (greater than the varistor voltage), the varistor is broken down at a low value, which is equivalent to a short circuit state.

However, after the varistor is struck, it can return to the insulation state; when the voltage higher than the varistor voltage is removed, it returns to the high resistance state. Therefore, if a zinc oxide arrester is installed on a power line, when a lightning strikes, the high voltage of the lightning wave causes the varistor to break down, and the lightning current flows into the earth through the varistor, which can control the voltage on the power line within a safe range. This protects the safety of electrical equipment.

Seven characteristics of zinc oxide arrester

1. Current carrying capacity This is mainly reflected in the ability of the lightning arrester to absorb various lightning overvoltages, power frequency transient overvoltages, and operating overvoltages.

2. Protection characteristics Zinc oxide lightning arrester is an electrical product used to protect various electrical equipment in the power system from overvoltage damage, and has good protection performance. Because the nonlinear volt-ampere characteristics of the zinc oxide valve plate are very good, only a few hundred microamperes of current pass through under normal working voltage, which is convenient for designing into a gapless structure, so that it has the characteristics of good protection performance, light weight and small size. When the overvoltage invades, the current flowing through the valve plate increases rapidly, while limiting the amplitude of the overvoltage and releasing the energy of the overvoltage. After that, the zinc oxide valve plate returns to a high-resistance state, allowing the power system to work normally.

3. Sealing performance The arrester components use high-quality composite jackets with good aging performance and good airtightness. Measures such as controlling the compression of the sealing ring and adding sealant are adopted. The ceramic jacket is used as the sealing material to ensure reliable sealing and stable performance of the arrester.

4. Mechanical properties mainly consider the following three factors: A. Earthquake force borne; B. Strong wind pressure acting on the arrester; C. The maximum allowable tension of the conductor borne by the top of the arrester.

5. Pollution-repelling performance: Gap-free zinc oxide arresters have high pollution resistance. The creepage distance levels stipulated in national standards are: Level II moderately polluted areas: creepage distance 20mm/kv Level III heavily polluted areas: creepage distance 25mm/kv Level IV extra heavy pollution areas: creepage distance 31mm/kv.

6. High operational reliability The reliability of long-term operation depends on the quality of the product and whether the product selection is reasonable. The following three aspects affect its product quality: A. The rationality of the overall structure of the arrester; B. The volt-ampere characteristics and aging resistance 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 may increase or a transient overvoltage with a high amplitude may be generated. The arrester has the ability to withstand a certain power frequency voltage increase within a certain period of time.