What is a Surge Arrester?

Surge arrester generally uses the body and air gap, and surge arrester does not assume system operating voltage, without considering the long-running voltage electrical ageing, also the body failure does not affect operation. when a lightning flash directly strikes the tower, part of the lightning current flows through the grounding wire to the adjacent tower, the other part of the lightning flows into the earth through the tower, grounding resistance of tower manifested transient resistance characteristic, it is generally characterized by the impulse grounding resistance. The lightning current associated with the location and atmospheric conditions, reducing grounding the resistance of tower is the main measures for improving lightning withstand the level of transmission lines without the use of surge arresters. Especially ˈ it is very difficult to reduce grounding resistance in the mountains, which led to line tripping frequently struck by lightning.

After the installation of surge arresters, surge arrester is parallel with insulator. When transmission line being struck by lightning, part of the lightning current flows through the grounding wire to the adjacent tower, the other part of the lightning current flows into the earth through the tower. When there is an excess of lightning current than the action value of the arrester, the current will flow through the arrester. After lightning current pouring, continuous frequency current flowing through the surge arrester is only mA level, the arrester will cut off continuous frequency current in the first zero crossings of current, so dielectric strength fast recover. As such a surge arrester is capable of ensuring that the insulator string flashover does not occur, thus achieve the goal which prevents transmission line lightning trip. Effect of lightning protection with surge arrester on transmission line has been compared with other lightning protection measures. The surge arresters can to a great extent reduce lightning accidents for transmission lines in complex terrain and high soil resistivity area. Distribution network develops rapidly at the present time, a large number of the line put into operation each year, expanding the size of the line increases the probability of lightning trip and created a lot of difficulty in lightning protection work. From the technical economy view, not all towers can be installed by surge arresters, so we should selectively install arresters combined with the line being struck by lightning frequency and landform characteristics and so on. Thus it can be said that the line surge arrester effectively avoids the lightning trip accidents occurring by way of installing line surge arrester after correctly choosing the tower which easily is struck by lightning so that lightning withstands the level of transmission lines has been effectively improved.

Given the current situation in lightning protection work proposed to continue to promote the application of line surge arrester, the effect of line arrester depends on correctly selecting the section or the tower which has chances of stroke. At the same time, a lot of arresters hanging on the towers to a certain extent increase the pressure of maintenance of the line, it should be appropriately controlled the scale.