Zinc oxide arrester is a widely used device.
The first reason: poor sealing
The common lightning protection device is mainly used to prevent lightning waves from causing damage to the electrical equipment of the substation. It not only has excellent nonlinear voltammetry characteristics, but also low cost, no gap, no freewheeling, large flow capacity and stable performance. However, accidents such as malfunctions and explosions can sometimes occur. Common failures are mainly caused by poor sealing.
Cause analysis: Poor sealing of zinc oxide arresters is mainly produced during the production process of the product. For example, zinc oxide arrester valve plates are not completely dry and contain water. Or during the assembly process, the sealing gasket of the arrester is improperly positioned or even not installed. Some manufacturers use substandard materials. For example, the porcelain bottle used is of poor quality with invisible holes that can cause moisture to seep in, making the interior moist.
Precautionary measures: In order to prevent the seal of the lightning arrester from being lax, the user should conduct a strict sealing test before use. In addition, in the operation and maintenance process of zinc oxide lightning arrester, especially after the thunderstorm, it is necessary to strengthen the inspection of the lightning arrester in order to find abnormalities in time. When performing regular preventive tests on a surge arrester using a zinc oxide arrester tester, the tester must carefully analyze the test data. Because when the arrester is damp, there may be no problems outside, but only through the test data can the internal defects be found.
The second reason: the internal valve plate is aging
Cause analysis: Valve plate aging generally occurs during operation. Due to the poor uniformity of the valve plate of the lightning arrester, the degree of aging is not the same, which will make the potentiometric distribution of the valve plate uneven. After running for a period of time, some valve plates deteriorate first, resulting in increased leakage current and power loss of the arrester.
Since the grid voltage remains constant, the remaining normal valves in the zinc oxide arrester are heavier, resulting in faster aging. This creates a vicious circle that eventually leads to an explosion accident inside the zinc oxide arrester, single-phase grounding, or the main body of the arrester.
Another reason why zinc oxide arrester valves accelerate aging is that zinc oxide arresters continue to operate at low voltages. This will result in a significant increase in the load on the zinc oxide arrester during operation, especially when the system is single-phase grounded, 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 valve, it is also necessary to select a lightning arrester with sufficient rated voltage and continuous working voltage in the design and selection. In addition, when inspecting, it is not only necessary to check whether the appearance of the arrester is damaged and flashover, but also to copy the leakage current value of the arrester and compare it with the initial value. If the value is too large, the defect should be reported in time and treated.
