Common Faults and Prevention of Zinc Oxide Lightning Arrester
A lightning arrester is a lightning protection device used to prevent lightning waves from invading the substation along the line and damaging electrical equipment. Under normal working voltage, the gap of the arrester will not be broken down, and the leakage current flowing through the arrester is very small. When a lightning wave strikes, the gap of the arrester will quickly be broken down, discharge to the ground, limit the overvoltage value of the protected equipment, and play a role in protecting the equipment.
In the 10 kV voltage level power grid, zinc oxide arresters are widely used. It not only has excellent non-linear 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. To this end, the author expresses his own opinions on the common faults and preventive measures of zinc oxide arresters.
Poor sealing
Cause Analysis:
The poor sealing of the arrester is mainly caused in the production process of the product. If the arrester valve is not completely dried, it contains moisture. 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.
Precautions:
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 arrester, especially after a thunderstorm, it is necessary to strengthen the inspection of the arrester in order to find abnormal situations in time. When conducting regular preventive tests on arresters, testers must carefully analyze the test data. Because when the arrester is damp, there may not be any problems in appearance, but only through the test data can the internal defects be found.
Internal valve aging
Cause 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 remaining normal valve plates in the arrester is heavier, resulting in faster aging. This forms a vicious circle, which eventually leads to an internal breakdown of the arrester, single-phase grounding or an explosion of the arrester body.
Another reason for the accelerated aging of the zinc oxide arrester valve is that the arrester continues to operate at a low voltage. This will cause the arrester load to be greatly increased during operation, especially when single-phase grounding occurs in the system, resulting in rapid aging of the valve plate.
Precautions:
In view of the aging problem of arrester valve discs, in addition to requiring manufacturers to improve the production process and improve the uniformity of the valve discs, it is also necessary to select an 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. .
Yichang Hengyuan Technology Co., Ltd. is a professional manufacturer of European-style cable connectors, plug connectors, cable branch boxes, American elbows, high-voltage vacuum circuit breakers, high-voltage load switches, lightning arresters, zinc oxide arresters, tank arresters, overvoltage protectors, Counters, monitors, heat-shrinkable cable accessories, cold-shrinkable cable accessories, T-heads, wall bushings, European cable accessories, American cable joints, transformer neutral point protection devices, fuses, isolating switches, PT cable heads, elbows Manufacturers of type cable joints, 10kV outdoor terminals, switch cabinets, cable intermediate joints, cable accessories and other products
