In areas with violent lightning activity, high soil resistivity of the line, and complex terrain, general lightning protection measures for transmission lines are often difficult to work. At this time, the installation of line arresters on the towers will be a good choice. The lightning arresters that can be selected are with or without gap arresters and series gap arresters. What are their advantages and disadvantages, and what conditions are they suitable for?
Nowadays, the widely recognized lightning protection measures for power transmission lines include the installation of ground lightning protection wires, reduction of the impact ground resistance of the tower, the installation of coupled ground wires, the unbalanced insulation method of insulator strings, and the installation of auto recloser devices for lines. The above measures are very effective for lightning protection of general transmission lines. However, in areas with violent lightning activity, high soil resistivity of the line, and complex terrain, the above measures are often difficult to work. At this time, the installation of line lightning arresters on the tower will be a good choice. There are many types of lightning arresters that can be selected when erecting lightning arresters on the poles and towers.
Without gaps lightning arrester
Advantages: Theoretically, it has the advantages of stable protection performance, short response time, and easy installation.
Disadvantages: Because the arrester is directly connected to the wire, and long-term live operation, once a fault occurs, it will directly affect the normal power supply of the line, so it is rarely used at present.
Lightning arrester with series gap
Advantages: Since the arrester body is separated from the high-voltage wire by a gap, the arrester does not withstand the continuous power frequency voltage during the normal operation of the system. Therefore, the arrester resistor does not have the problem of aging. Even if the arrester body fails, due to the isolation effect of the gap, Will not affect the operation of the system. In theory, line arresters with series gaps have the advantages of high reliability and long operating life. At present, 90% of line arresters in power system operation are line arresters with series gaps.
Disadvantages: Since the gap is a pure air gap, there is no other object to support during installation. At the same time, it is limited by the mechanical strength of the arrester body. Therefore, the arrester can only be installed vertically; while the arrester gap size and body size are fixed, The length of the line insulator string varies according to different regions and terrains. Therefore, during installation, different auxiliary tooling must be temporarily processed according to the installation position and the shape of the tower to meet the installation requirements, and the installation structure is more complicated.
New-type line arrester technology and structural characteristics
A new type of lightning arrester is formed by installing maintenance-free lightning arrester devices, that is, fault indicator, thermal explosion type disconnector and suspension auxiliary mechanism, while optimizing the internal structure of the arrester. When this new type of arrester fails, the disconnector will act quickly to withdraw the faulty arrester from the power transmission system, eliminate the permanent grounding of the system in time, and provide an obvious identification for the faulty arrester, which is convenient for maintenance personnel to find the fault point in time and perform maintenance and replacement. Due to the use of maintenance-free devices, the protection level of the arrester can be improved (obtained by reducing the residual voltage of the arrester), and it is possible to increase the protection distance to a certain extent, minimize the number of installations of the arrester, and further reduce the line Lightning protection costs. Now this new type of arrester is being produced and widely used, replacing the above two arresters, effectively improving the reliability of power supply.