Zinc oxide arrester is mainly a kind of equipment widely used below 1000KV.
A common lightning protection device mainly used to prevent lightning waves from damaging the electrical equipment of substations. It not only has excellent nonlinear volt-ampere characteristics, but also has low cost, no gap, no freewheeling, large flow capacity and stable performance. However, accidents such as breakdown and explosion sometimes occur.
Common failures are mainly caused by poor sealing.
Reason analysis: The poor sealing of zinc oxide arrester is mainly produced in the production process of the product. For example, the zinc oxide arrester valve plate is not completely dried and contains water. Or during assembly, the sealing gasket of the arrester was placed in an improper position or even not installed. Some manufacturers use unqualified materials. For example, the porcelain bottles used are of poor quality, with invisible holes that can cause moisture to penetrate and make the interior damp.
Precautionary measures: In order to prevent the imperfect sealing of the arrester, the user should conduct a strict sealing test before using it. In addition, during the operation and maintenance of the zinc oxide arrester, especially after a thunderstorm, it is necessary to strengthen the inspection of the arrester in order to find abnormalities in time. When using a zinc oxide arrester tester to conduct regular preventive tests on arresters, testers must carefully analyze the test data. Because when the arrester is damp, there may not be any problems on the outside, but only through the test data can the internal defects be found.
The second reason is: the internal valve plate is aging
Reason analysis: the aging of the valve plate generally occurs during operation. Due to the poor uniformity of the arrester valve plate, its aging degree is not the same, which will make the valve plate potential distribution uneven. After running for a period of time, some of the valve discs deteriorate first, causing the leakage current and power loss of the arrester to increase.
As the grid voltage remains unchanged, the burden on the rest of the normal valves in the zinc oxide arrester is heavier, resulting in faster aging. In this way, a vicious circle is formed, which eventually leads to an internal breakdown of the zinc oxide arrester, single-phase grounding or an explosion accident of the arrester body.
Another reason for the accelerated aging of the zinc oxide arrester valve is that the zinc oxide arrester continues to operate at a low voltage. This will lead to a great increase in the load of the zinc oxide arrester during operation, especially when a single-phase grounding occurs in the system, resulting in rapid aging of the valve plate.
Preventive measures: In view of the aging problem of zinc oxide arrester valves, in addition to requiring manufacturers to improve the production process and improve the uniformity of the valves, it is also necessary to select a surge arrester with sufficient rated voltage and continuous operating voltage when designing and selecting. In addition, during inspections, not only should the appearance of the arrester be checked for damage and flashover, but also the leakage current value of the arrester should be copied and compared with the initial value. If the value is too large, the defect should be reported in time and dealt with.