Common faults and prevention of zinc oxide arresters
A lightning arrester is a lightning protection device used to prevent lightning waves from invading the substation along the lines and damaging electrical equipment. Under normal operating voltage, the arrester gap will not be broken down, and the leakage current flowing through the arrester is very small. When a lightning wave strikes, the arrester gap will soon be broken down and discharge to the ground, limiting the overvoltage value of the protected equipment and protecting the equipment.
In the 10 kV voltage level power grid, zinc oxide arresters are widely used. 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. To this end, the author expresses his own opinions on the common faults and preventive measures of zinc oxide arresters.
Poor seal
Reason analysis:
Poor sealing of arresters mainly occurs during the production process of the product. If the arrester valve plate is not completely dried, it contains moisture. Or during assembly, the sealing gasket of the arrester is placed improperly or even not installed. The materials used by some manufacturers are substandard. For example, the porcelain bottles used are of poor quality and have invisible holes that can also cause moisture to penetrate and make the interior damp.
Precautions:
In order to prevent poor sealing of the arrester, users should conduct strict sealing tests before use. In addition, during the operation and maintenance of the arrester, especially after a thunderstorm, it is necessary to strengthen the inspection of the arrester to detect abnormal conditions in time. When conducting regular preventive tests on arresters, test personnel must carefully analyze the test data. Because when the arrester gets wet, there may not be any problems on the outside, but internal defects can only be discovered through test data.
Internal valve plate aging
Reason analysis:
Valve plate aging generally occurs during operation. Due to the poor uniformity of the arrester valve plates and their varying degrees of aging, the potential distribution of the valve plates will be uneven. After running for a period of time, some valve plates deteriorate first, causing the leakage current and power loss of the arrester to increase.
Since the grid voltage remains unchanged, the burden on the remaining normal valve plates in the arrester increases, resulting in accelerated aging. This forms a vicious cycle, which eventually leads to internal breakdown of the arrester, single-phase grounding or explosion of the arrester body.
Another reason for the accelerated aging of zinc oxide arrester valves is that the arrester continues to operate at a low voltage. This will greatly increase the load on the arrester during operation, especially when a single-phase grounding occurs in the system, causing rapid aging of the valve plate.
Precautions:
In response to the aging problem of arrester valve plates, in addition to requiring manufacturers to improve the production process and improve the uniformity of valve plates, they must also select arresters with sufficient rated voltage and continuous operating voltage during design selection.
In addition, during the inspection, not only should the appearance of the arrester be checked for damage, flashover, etc., but the leakage current value of the arrester should also be taken 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. specializes in the production of European-style cable joints, plug-and-pull heads, cable branch boxes, American-style elbow joints, high-voltage vacuum circuit breakers, high-voltage load switches, arresters, zinc oxide arresters, tank arresters, over-voltage protectors, counters, monitors, heat-shrinkable cable accessories, Manufacturer of cold shrink cable accessories, T-heads, wall bushings, European cable accessories, American cable joints, transformer neutral point protection devices, fuses, isolating switches, PT cable heads, elbow cable joints, 10kV outdoor terminals, switch cabinets, cable intermediate joints, cable accessories and other products
