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How to Prevent overhead insulated cable from lightning strike?


According to the mechanism of lightning strikes on insulated conductors, in general, the corresponding preventive measures are mainly "drainage" and "blockage".

Insulated wire cores enter the water, leading to electrochemical corrosion of the zinc oxide surge arrester wire arc. At the same time when subjected to the power frequency voltage may cause aging of zinc oxide valve, increase the amount of operation and maintenance.

In economically developed countries, transmission and distribution of electricity using overhead insulated conductors takes a long time, and a great deal of operating experience has been accumulated. In order to reduce the increasing rate of accidents caused by lightning strikes, a number of preventive measures and methods have been adopted, as follows:

(1) Overhead lightning protection line

In open areas, overhead conductors are erected on the same pole to cope with induced over-voltages on the insulated overhead distribution lines. This is a traditional method with large investment. However, due to the low insulation level of the distribution line design, after the lightning strikes the overhead lightning protection line, it is very easy to cause flashback, and it will still cause the power frequency to continue to melt the insulated conductors. Therefore, this method is currently used less frequently abroad.

(2) Zinc Oxide Arrester

In recent years, people have used the characteristics of the nonlinear resistance of zinc oxide surge arresters and the characteristics of quick-cutting the freewheeling current, which are widely used in the line to limit lightning overvoltage, but its protection range is small, and the reason why the insulating layer must be broken must be caused. 

This method has a very good protection effect. This method has been used in Japan, the United States, Canada, and other countries by investing heavily.