The aging of the internal valve plate of the high-voltage arrester generally occurs during operation. We not only check the appearance of the high-voltage arrester for damage and flashover, but also copy the leakage current value of the high-voltage arrester and compare it with the initial value. If the value is too high, we should promptly report the defect and handle it. Due to the poor uniformity of the high-voltage arrester valve plate and the different degrees of aging, the potential distribution of the valve plate is uneven. After operating for a period of time, some valve discs* deteriorate first, resulting in increased leakage current and loss of arrester power. Since the grid voltage remains unchanged, the load on other normal valves in the high-voltage arrester increases, causing its aging rate to accelerate. This forms a vicious cycle, eventually leading to internal breakdown of the high-voltage arrester, single-phase grounding of the arrester body, or explosion.
Metal oxide arrester
Another reason for the accelerated aging of the high-voltage arrester valve plate is the low continuous operating voltage of the arrester. This will greatly increase the load of the high-voltage arrester during operation, especially when the system is single-phase grounded, resulting in rapid aging of the valve plate.
Preventive measures: In response to the aging problem of high-voltage arrester valve plates, in addition to requiring manufacturers to improve the production process and improve the uniformity of valve plates, high-voltage arresters with sufficient rated voltage and continuous operating voltage should also be selected during design and selection. For example, the high-voltage arrester valve plate is not completely dry and contains water, or the 10kv high-voltage arrester sealing gasket is improperly placed, or even not installed during assembly. Some manufacturers use substandard materials. For example, the porcelain bottles used are of poor quality and have invisible holes, which can also lead to moisture penetration and internal dampness. During the operation and maintenance of high-voltage arresters, especially after thunderstorms, patrol inspections of high-voltage arresters should be strengthened to detect abnormalities in a timely manner. When conducting regular preventive tests on arresters, test personnel should carefully analyze the test data. Because when the arrester is damp, there may be no problem in appearance, but internal defects can only be discovered through test data.
High voltage arrester
There are three failure modes for high-voltage arrester valve plates:
(1) The leakage current increases and the varistor voltage significantly reduces to zero;
(2) Cracking: If the energy caused by overvoltage is too large and exceeds the ultimate carrying capacity of the selected high-voltage arrester, ceramic cracking will occur when the high-voltage arrester suppresses the overvoltage;
(3) Perforation. If the overvoltage peak is particularly high, the 35kV high-voltage arrester will cause instantaneous breakdown, which will appear as perforation.
Among them, under the premise of hierarchical lightning protection, the failure modes of high-voltage arresters are mostly degradation and perforation (i.e. short circuit). Therefore, when using a high-voltage arrester, appropriate circuit breakers or fuses must be connected in series to avoid accidents caused by short circuits.
Currently, the internationally popular high-voltage arresters organically combine varistor with current limiting, overcurrent, and degradation alarm devices. In addition to overvoltage protection, it also has the function of preventing its own deterioration and circuit short circuit.
Lightning arrester manufacturer
