The electric energy we use every day is transmitted from far away through the transmission line. Since the transmission line is very long, it will be affected by lightning strikes. Therefore, the accidents of power transmission failure are also increasing day by day, which seriously affects the electrical equipment. and people's normal production and life.
The continuous advancement of science and technology brings more convenience and safety. In terms of line lightning protection, line-type synthetic insulated zinc oxide arresters are widely used abroad. my country is also making continuous progress and innovation in lightning protection. Nowadays, lightning arresters It has been widely used in the power sector. In transmission lines, there are several types of arresters commonly used at present: zinc oxide arresters, valve arresters, tubular arresters and low-voltage zinc oxide arresters used in low voltage.
The valve plate in the zinc oxide arrester has a very high resistance under normal voltage and only a very small leakage current, and when the line is struck by lightning, the valve plate will instantly become a very low resistance, which makes the line It is directly connected to the ground, and the current generated by the lightning strike flows into the ground. After the lightning strike, the valve will return to its previous insulation state.
The unit volume of the zinc oxide arrester valve can absorb more energy, and it can also be used in parallel, so it is a good overvoltage protection element when protecting ultra-high voltage transmission lines and large-capacity capacitor banks. Zinc oxide arrester The nonlinear volt-ampere characteristics are very good, there is no arc extinguishing problem and gap breakdown characteristics.
The basic principle of lightning arresters in transmission lines: without installing lightning arresters, to improve the level of lightning resistance, the only way is to reduce the resistance value between the tower body and the ground, which is easier to achieve in plains, but more difficult in mountainous areas. Therefore, power lines are often struck by lightning. After the arrester is installed, when the line is struck by lightning, if the lightning current exceeds a certain value, the arrester will act to release the current generated by the overvoltage. Because the arrester has the function of clamping point (you can Baidu it yourself), so the requirement for grounding resistance is not so high, which is more suitable in mountainous areas. After installing the arrester, the line lightning protection level will be greatly improved, but Before the arrester is used, all parameters of the arrester must be measured and tested, so as to ensure the reliable operation of the arrester.
There are several points for the detection of arresters: insulation resistance value, DC and leakage current value, AC leakage current value under normal operating voltage, etc.
When installing lightning arresters on the line, they must also be installed according to the specifications. During installation, the lightning arresters must not be stressed, and a certain safety distance must be ensured. The ground wire of the lightning arrester must be laid separately, and the cross-sectional area must be more than 25 square meters, if conditions permit In this case, the grounding resistance should be as small as possible. After being put into use, the arrester should also be maintained regularly, which can be carried out by referring to some detection standards of the arrester.