Protection of Power Transmission Lines Against Lightning

Energy transmission (power transmission) lines that carry electrical energy between generation points and consumption points are structures exposed to both lightning strikes and overvoltages. In order to transmit electrical energy without interruption, the insulator and insulation mechanisms must be designed in accordance with the voltages that may occur. Based on our field experience, the most important factors disrupting energy continuity in these systems are lightning strikes and transient regime changes. When lightning strikes the pole, shield wire, or phase conductor in transmission lines, a flashover occurs due to the sudden increase in voltage across the insulator. As a result, this situation causes insulator breakage, deterioration of transformer insulation, and power outages.

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Lightning strike on energy transmission line

On the other hand, especially in rainy weather, lightning strikes on energy transmission lines may cause short circuits. This situation leads to damage and burnout of users’ devices. Therefore, energy transmission lines must be protected against such failures.

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For energy transmission lines, internal lightning protection systems should primarily be considered. With surge arresters suitable for both medium and high voltage, precautions can be taken against lightning strikes, sudden overvoltages, and fault-related issues. Transformer substations, switchyards, and high-voltage cables are protected by determining appropriate voltage levels and using surge arrester systems.

Another important system for protecting energy transmission and distribution lines against lightning is external lightning protection systems. Shield wires, Faraday cages (in transformer systems), or air terminals can be used. Shield wires may have a smaller cross-section than normal conductors; however, they must have sufficient mechanical strength to withstand lightning strikes without damage. In addition, shield wires should be grounded at every pole whenever possible. When steel poles are used, the pole body itself can serve as the down conductor without the need for a separate down conductor.