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Image of Lightning Arrester
A lightning arrester, also known as a surge arrester, is a device used in electrical power systems and telecommunications to protect the insulation and conductors of the system from the damaging effects of lightning. Here are some key points about lightning arresters:
Function
• Protection Against Over-Voltage: The primary function of a lightning arrester is to protect electrical equipment from over-voltage transients caused by external (lightning) or internal (switching) events.
• Voltage Clamping: It does this by providing a path to ground for high-voltage surges, clamping the voltage to a safe level.
Types
1. Rod Gaps: Simple, cost-effective, and robust, but less precise.
2. Expulsion-Type Arresters: Utilizes a gas expulsion mechanism, primarily used for distribution systems.
3. Valve-Type Arresters: Incorporates non-linear resistors and has better energy handling capability.
4. Metal-Oxide Varistor (MOV) Arresters: Commonly used due to their superior performance, made of zinc oxide without gaps, and can handle high-energy transients.
Components
• Spark Gap: Discharges the over-voltage to the ground when a certain voltage threshold is exceeded.
• Non-Linear Resistor: Often made of zinc oxide, it changes resistance with the voltage level to absorb the energy of the surge.
Placement
• At Entry Points: Installed at the point where power lines enter a building or substation to intercept lightning strikes.
• Along Power Lines: Placed at intervals along overhead power lines to protect the entire length of the line.
Operation
• Under normal conditions, a lightning arrester is an open circuit and does not conduct electricity.
• When a surge occurs, the arrester momentarily becomes a low-impedance path to ground, diverting the surge current away from sensitive equipment.
• After the surge has passed, the arrester returns to its high-impedance state.
Applications
• Power Transmission and Distribution: Protects transformers, circuit breakers, and other critical infrastructure.
• Telecommunications: Shields sensitive communication lines and equipment.
• Residential and Commercial Buildings: Guards against surges that can damage home appliances and electronics.
Maintenance
• Regular inspection and testing are essential to ensure that the arrester is in good working condition.
• Damaged or degraded arresters should be replaced to maintain system protection.
By diverting excessive voltage safely to the ground, lightning arresters play a crucial role in preventing damage to electrical infrastructure and maintaining the reliability of power and communication systems.
