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The lightning protection equipment is used to protect power systems and buildings from damage caused by lightning overvoltage. Their main function is to introduce lightning current into the ground, prevent lightning current from passing through the equipment in the power system or building, and thus avoid accidents such as equipment damage or fire. Lightning protection equipment can be divided into different types according to their application areas and principles. The following are the main types, working principles and structural characteristics of lightning protection equipment:
I. Types of lightning protection equipment
1. Lightning Rod
2. Ground Wire
3. Surge Arrester
4. Surge Protection Device (SPD)
5. Grounding System
II. Working Principle and Structural Characteristics
1. Lightning Rod
- Working Principle: Lightning rods use the principle of tip discharge. When thunderclouds approach, the tip of the lightning rod will first guide the charge released by lightning to form a tip corona discharge, which will then attract lightning current through the lightning rod into the grounding device, safely introducing lightning current into the ground to prevent it from passing through buildings and equipment.
- Structural features:
- Main structure: The lightning rod consists of a metal rod (usually copper or stainless steel) and a grounding device. The metal rod is used to guide the lightning current, and the grounding device ensures that the lightning current can flow smoothly into the ground.
- Installation location: The lightning rod is generally installed at the highest point of a building or tall structure to ensure that lightning strikes the lightning rod first rather than other parts.
- Applicable scenarios: Lightning rods are widely used in buildings, power plants, substations and other occasions, especially high-rise buildings and important facilities that need to be protected.
2. Lightning conductor
- Working principle: The lightning conductor is a metal conductor erected above the transmission line. When lightning strikes the line, the lightning strikes the lightning conductor first, and then the lightning current is introduced into the ground through the grounding device, thereby protecting the transmission line below from lightning damage.
- Structural features:
- Conductor structure: The lightning conductor is usually made of steel-core aluminum stranded wire or galvanized steel wire, which has good conductivity and mechanical strength.
- Installation method: Lightning arresters are usually laid along the entire line of the transmission line and connected to multiple grounding devices to ensure that lightning current can be quickly introduced into the ground at any lightning strike point.
- Applicable scenarios: Mainly used for overhead transmission lines, especially long-distance high-voltage transmission lines, to ensure that transmission lines are protected from lightning damage.
3. Lightning arrester
- Working principle: The lightning arrester uses the voltage limiting principle to present high impedance when the voltage is normal in the power system. When lightning or operating overvoltage occurs, the resistance of the lightning arrester drops sharply, and the overvoltage energy is quickly discharged to the ground through the grounding system, thereby protecting electrical equipment from overvoltage damage.
- Structural features:
- Main material: The lightning arrester is mainly composed of metal oxide (such as ZnO) varistors or nonlinear resistance materials. When the voltage exceeds a certain value, its resistance will drop sharply and release current; while at normal voltage, its resistance is very high and has almost no effect on normal operation.
- Protection range: The lightning arrester can be installed near equipment such as substations, generators, transformers, and transmission lines to protect these equipment from overvoltage.
- Applicable scenarios: Widely used in power systems, especially for the protection of high-voltage and ultra-high-voltage equipment.
4. Surge Protector (SPD)
- Working principle: Surge protector (SPD) is used to protect low-voltage distribution systems and terminal equipment from lightning overvoltage or operational overvoltage. Its working principle is similar to that of a lightning arrester. It can quickly guide excess current to the ground when overvoltage occurs, and quickly return to a high-resistance state after normal voltage is restored to maintain normal operation of the line and equipment.
- Structural features:
- Main structure: SPD is composed of components such as varistors, gas discharge tubes or transient suppression diodes, which can respond to overvoltage and discharge current instantly.
- Installation method: SPD is usually installed next to distribution boxes, power inlets of electrical equipment or key electrical equipment, and plays a secondary protection role against lightning strikes and operational overvoltage.
- Applicable scenarios: Suitable for end-user protection in low-voltage distribution systems, such as computers, communication equipment, industrial control systems, etc.
5. Grounding system
- Working principle: The grounding system is the basic part of the lightning protection equipment. Its function is to safely introduce lightning current into the ground, thereby preventing lightning current from passing through the power system or building. By connecting with lightning rods, lightning arresters and other equipment, the grounding system can provide a low-impedance path to ensure that the lightning current is quickly and safely released to the ground.
- Structural features:
- Grounding electrode: The grounding electrode is usually a metal rod driven vertically into the ground or a conductor buried underground to ensure good contact with the soil.
- Grounding wire: The grounding wire connects the lightning protection device and the grounding electrode to ensure that the lightning current can be smoothly conducted to the ground. Copper wire or galvanized steel wire is usually used to ensure good conductivity and corrosion resistance.
- Soil resistivity: The performance of the grounding system is closely related to the resistivity of the soil. The grounding effect is better in places with lower soil resistivity. If necessary, the grounding resistance can be reduced by adding a grounding grid or increasing the length of the grounding electrode.
- Applicable scenarios: The grounding system is the basis of all lightning protection measures and is applicable to various types of buildings, power equipment, communication systems, etc.
The lightning protection equipment is divided into lightning rods, lightning conductors, lightning arresters, surge protectors and grounding systems according to their uses and working principles. They protect buildings, power equipment and user equipment from lightning damage by guiding lightning current, safely diverting current and limiting voltage. Each device has its own unique structural characteristics and applicable scenarios. By comprehensively using these lightning protection devices, lightning strikes and the damage they cause can be effectively prevented.
