The zinc oxide arrester is a lightning arrester with good protection performance. Using the good nonlinear volt-ampere characteristics of zinc oxide, the current flowing through the arrester at normal operating voltage is extremely small (microampere or milliampere); when overvoltage is applied, the resistance drops sharply, and the energy of the overvoltage is discharged. Achieve the effect of protection. The difference between this arrester and the conventional arrester is that it has no discharge gap and utilizes the nonlinear characteristics of zinc oxide to function as a discharge and break.
Seven characteristics of zinc oxide arrester:
1. Flow capacity
This is mainly reflected in the arrester's ability to absorb various lightning overvoltages, power frequency transient overvoltages, and operating overvoltages.
2. Protection characteristics
The zinc oxide surge 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 non-linear volt-ampere characteristics of the zinc oxide valve plate are excellent, only a few hundred microamps of current is passed through the normal operating voltage, which is convenient to design a gapless structure, which has good protection performance, light weight and small size. feature. When the overvoltage intrudes, the current flowing through the valve plate increases rapidly, and the amplitude of the overvoltage is limited, and the energy of the overvoltage is released. Thereafter, the zinc oxide valve plate returns to a high resistance state, so that the power system works normally.
3. Sealing performance
The arrester component adopts a high-quality composite jacket with good aging performance and good air tightness. It adopts measures such as controlling the compression of the sealing ring and adding sealant. The ceramic jacket is used as a sealing material to ensure reliable sealing and stable performance of the arrester.
4. Mechanical properties
The following three factors are mainly considered: the seismic force to withstand; the maximum wind pressure acting on the arrester; the maximum allowable tensile force of the wire at the top of the arrester.
5. Decontamination performance
The gapless zinc oxide arrester has high stain resistance.
The creepage ratio specified by the national standard is: Class II medium pollution area: creepage ratio 20mm/kv; Class III heavy pollution area: creepage ratio 25mm/kv; Grade IV heavy pollution area: creepage ratio 31mm/kv.
6. High operational reliability
The reliability of long-term operation depends on the quality of the product and whether the selection of the product is reasonable. The quality of the products affecting it mainly has the following three aspects: the rationality of the overall structure of the arrester; the volt-ampere characteristics and aging resistance of the zinc oxide valve; the sealing performance of the arrester.
7. Power frequency tolerance
Due to various reasons such as single-phase grounding, long-line capacitance effect and load shedding in the power system, the power frequency voltage may increase or a transient over-voltage of a higher amplitude may be generated. The arrester has a certain power frequency for a certain period of time. The ability to increase voltage.
The role of zinc oxide arrester
Each type of arrester has its own advantages and characteristics, and needs to be used in different environments to achieve good insulation. The arrester is equivalent to an insulator at rated voltage and will not cause any action. In the event of a crisis or high voltage, the arrester will act to introduce current into the earth and effectively protect the power equipment.