Metal oxide surge arrester without gaps failed common reason and prevention way
Metal oxide surge arrester without gaps is used to prevent intrusion along the road a substation damaged electrical equipment lightning protection devices. In the normal operating voltage, the gap is not arrester breakdown, leakage current flows through the arrester very small value. When lightning strikes, lightning arrester gap will soon be breakdown, and the surge current is discharged to ground, which is limiting the value of over-voltage protection devices, played the role of protective equipment.
In the 10 kV voltage level grid, metal oxide surge arresters without gaps are widely used. It not only has excellent non-linear volt-ampere characteristics, and low cost, no gap, no freewheeling, flow capacity, stable performance. But also occurred breakdown and explosion and other accidents. To this end, the author MOA common faults and preventive measures to express their views.
Analysis: arrester bad seal is mainly produced in the production process. If drying is not complete arrester valve plate containing moisture. Or assembly, gasket arrester improper placement or is not installed. Some manufacturers use substandard materials, such as the use of poor quality porcelain with invisible holes can also cause water infiltration, so that the internal moisture.
Precautions: To prevent bad seal arresters, the user before use, should be strictly tightness testing. In addition, the arrester operation and maintenance process, especially after a thunderstorm, lightning arrester to strengthen inspections in order to detect anomalies. Arrester conducted on regular preventive test, the test personnel should carefully analyze the test data. Because arrester damp, you may not see any problem in appearance, but the experimental data can be found only through internal defects.
Aging of the internal valve
Analysis: valves aging generally arise during operation. As arrester valve uniformity is poor, its not the same degree of aging, it will make valves potential distribution is uneven. After running for some time, some degradation of the first valve, causing the arrester leakage current and power dissipation increases.
Since the grid voltage constant, remaining within the normal valve arrester burden, leading to accelerated aging. Thus forming a vicious cycle, eventually leading to the occurrence of internal breakdown occurred arrester single phase or arrester body explosion.
Zinc oxide arrester valve causes accelerated aging is another reason arrester continuous operating voltage is low. This will cause the running process, especially when the system single-phase ground, much heavier load arrester, causing rapid aging valves.
Precautions: For the arrester valve aging issues, in addition to require manufacturers to improve the production process and improve the uniformity of valves, but also in the design and selection of the selection has enough rated voltage and continuous operating voltage of the arrester.
In addition, inspections, not only to see whether the appearance of damaged arrester flashover phenomenon, but also Beater arrester leakage current value and compare it with the initial value, if the value is too large should be promptly reported to the defects and give treatment .