Lightning protection measures for distribution lines - Solutions - Huaqiang Electronic Network

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In low-voltage distribution networks, the average height of the poles is typically lower than that of transmission lines. Additionally, the surrounding environment may include buildings or trees that provide some natural shielding against lightning strikes. As a result, the likelihood of direct lightning strikes on these lines is relatively lower. However, due to the limited insulation level in distribution systems and the close spacing between conductors, even a direct strike can cause tripping or damage. This makes it essential to enhance the lightning protection measures for distribution networks in order to ensure a more reliable power supply.

The fundamental technical measures for protecting distribution lines from lightning are as follows:

Protection against direct lightning strikes: To improve the lightning resistance of distribution lines, it's important to increase the insulation level of the line. Using porcelain cross arms or high-grade insulators can help achieve this. Given the large number of distribution lines, their wide coverage, and long lengths, it's not economically feasible to install overhead ground wires or lightning rods for every section. Moreover, since most distribution lines operate with an ungrounded neutral system and have shorter spans, the top conductor often naturally acts as a protective conductor. In such cases, installing a grounded protection gap on the insulator of the top wire is considered the most effective method.

Protection against induced lightning: Distribution lines may have certain weak points in terms of insulation, such as metal towers, tall structures, iron cross arms, or towers with guy wires and terminal poles. These areas should be equipped with surge arresters to prevent damage caused by induced lightning currents.

All electrical equipment along the distribution line—such as distribution transformers, circuit breakers, and isolating switches—should be protected according to their criticality. This includes using lightning arresters or protection gaps to ensure comprehensive protection and minimize the risk of lightning-induced failures. It's crucial to implement these measures thoroughly to avoid any potential gaps in the system’s lightning protection strategy.