The lightning protection device is mainly composed of the following three parts:
One, surge protectorIncluding lightning rods, lightning wires, lightning mesh, lightning strips, and lightning arresters, these are the metallic parts that directly receive lightning strikes.
Lightning rodGenerally installed at the top of high-rise buildings and chimneys, it utilizes the principle of corona discharge to prevent direct lightning strikes at the installation location. It is typically mounted on frames, pillars, or buildings, with its lower end welded to the grounding device via a down conductor.
Lightning rodCommonly used to be installed on high-voltage overhead transmission lines to protect the lines from direct lightning strikes, and can also be used to protect longer single-story buildings. As the lightning rod is both overhead and grounded, it is also known as an overhead ground wire.
Surge protection grid and surge protection stripUsed commonly to protect buildings from direct lightning strikes and induced lightning. The lightning rod band is generally installed around the roof, elevated 100mm above the roof surface.150mm, supports inter-card distance of 1m5m. In addition to being installed around the roof perimeter, the lightning protection mesh should also be connected horizontally and vertically with round or flat steel bars on the roof surface when necessary.
Surge protectorA surge protector designed to prevent lightning overvoltage from damaging distribution and other electrical equipment, installed at the input end of the protected equipment. Its top is connected to overhead transmission lines, and the bottom is grounded. Surge arresters are mainly used to protect electrical equipment, belonging to a type of specialized lightning protection device. Among them, valve-type surge arresters are a commonly used lightning protection device for transformers and distribution stations; tubular surge arresters are generally used on transmission lines; protection gaps are simple and cost-effective lightning protection devices, also known as simple surge arresters, usually installed at the entry point of the line to protect devices such as electricity meters.
Two, downstream lineThe middle section of the lightning protection device connects the air terminal above and the grounding device below. Typically installed on the exterior wall of buildings, it is grounded through a short circuit. Each building usually has at least two down conductors. The down conductors are metallic conductors connecting the air terminal to the grounding device, commonly using round steel or flat steel, with round steel being preferred. The diameter of the round steel should not be less than 8mm, and the cross-section of the flat steel should not be less than 12mm x 4mm. The down conductors should be laid along the exterior walls of buildings or structures and grounded through the shortest path. When buried underground, the cross-section should be increased by one level, i.e., the diameter of the round steel should not be less than 10mm, and the cross-section of the flat steel should not be less than 20mm x 4mm. Metal components of buildings or structures, such as fire ladders, steel columns, can also serve as down conductors, but electrical pathways should be formed between all parts. The down conductors must meet the requirements for mechanical strength, corrosion resistance, and thermal stability.
Section 3: Grounding EquipmentIncluding buried ground wires and grounding bodies underground, in soils with strong corrosiveness, anti-corrosion measures such as galvanizing or increasing the cross-sectional area should be taken. The grounding system is an important part of lightning protection, discharging lightning currents to the earth, and limiting the ground voltage of the lightning protection system from being too high. In addition to independent lightning rods, the lightning protection grounding system can be shared with other grounding systems as long as the grounding resistance meets the requirements. Generally, galvanized round steel, angle steel, flat steel, etc., are used to connect into horizontal grounding loops, grounding strips, or vertical grounding bodies, buried at a certain depth in moist soil. The reinforced concrete foundation of modern buildings can also serve as a grounding system.
