When the impact grounding resistance of the lightning rod (iron) tower is ≤100Q, only two high-voltage arresters are installed on the two phases A and C. When the rod (iron) tower is struck by lightning, the lightning resistance strength of the line segment can be increased to 1.6~2.0 times: For example, three high-voltage arresters are installed on the three phases A, B, and C. When a lightning strikes an iron tower, the line segment's lightning resistance level can be increased to 3 to 3.6 times. If three more high-voltage arresters are installed on two adjacent (iron) towers, when a lightning strikes the tower, the line's lightning resistance level can be increased to lJ350kA or above, fully meeting the lightning protection requirements for AC transmission lines.
The impact grounding resistance of a pole (iron) tower has a basically linear relationship with the lightning resistance level. The smaller the impact grounding resistance, the higher the lightning resistance level. The impact grounding resistance of a pole (iron) tower equipped with a high-voltage arrester and its adjacent pole (iron) tower should be reduced as much as possible to obtain better lightning protection effects.
Generally, the following principles should be followed when selecting the installation point of a high-voltage arrester:
Based on the statistical results recorded over the years and the use of lightning positioning systems, etc., the range of pole (iron) tower or line segments that are susceptible to lightning strikes is determined: 3.2.2 The range of the pole (iron) tower segment is analyzed, and the pole (iron) tower or lightning protection (lightning strike) line segment (iron tower or lightning protection line) is confirmed, or which course is dominant.
For the power frequency grounding resistance of each pole (iron) tower within the measurement line section, minimum measures should be taken for poles (iron) towers with higher values.
For lightning shielding, 10KV high-voltage arresters can be installed only in the easy-to-shield phase or connected at both ends. When lightning strikes back, high-voltage arresters and metal oxide arresters should be installed on all three phases. If the grounding resistance of the adjacent pole (iron) tower is high or it is expected to further improve the lightning resistance level, high-voltage arresters should be installed on both sides of the adjacent pole (iron) tower.
The installation point should be selected so that the insulators (strings) in the protected line segment do not flicker regardless of whether they are within the protected line segment or part of the protected line.
The installation of high-voltage line arresters should ensure that the high-voltage arrester is not deflected by the wind at any time, and the safety distance between the high-voltage arrester and line insulators (strings) and pole iron towers should comply with standard regulations. When the parallel suspension device extends along the line direction, there are many varieties of 35kV, 110kV, and 220kV high-voltage arresters. Users should choose according to the actual usage conditions.
The safety distance between insulator wires (strings) should be 0.8 times, but not less than the standard value.
How to operate and maintain it? The arrester manufacturer tells you!
After the high-voltage line lightning protection device is put into use, its appearance should be checked for abnormalities during line inspection, and the number of discharges and leakage current values of its series connection or online monitoring should be recorded.
