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What is a lightning arrester ?

A lightning arrester, also known as a surge arrester or lightning rod, is a crucial component in electrical systems designed to protect equipment and structures from the damaging effects of lightning strikes and electrical surges. The primary function of a lightning arrester is to provide a low-resistance path for the excess electrical energy generated during a lightning event, diverting it safely to the ground and preventing it from causing harm to sensitive equipment or structures.

The design of a lightning arrester typically includes a metal rod or conductor connected to the highest point of a structure, such as a building or a transmission tower. This elevated conductor serves as a target for lightning strikes. When a lightning bolt approaches, the arrester provides a path of least resistance for the electrical discharge to follow, creating a safe route for the lightning’s energy to dissipate harmlessly into the ground.

There are two main types of lightning arresters: rod-type and distribution-class.

  1. Rod-type Lightning Arresters:
    • Air Terminals: These are the pointed metal rods placed at the highest points of a structure. They attract the lightning strike.
    • Conductors: Connected to the air terminals, these conductors provide a path for the lightning current to flow.
    • Grounding System: The conductors lead to a well-designed grounding system, ensuring the safe dissipation of the lightning energy into the ground.
  2. Distribution-Class Lightning Arresters:
    • Metal Oxide Varistors (MOVs): These arresters contain MOVs, which are semiconductor devices that have high resistance under normal operating conditions but become highly conductive during voltage surges.
    • Housings: The MOVs are housed within insulating materials and connected in parallel with the equipment to be protected.

During normal operation, the lightning arrester remains passive. However, when a lightning strike or voltage surge occurs, the arrester becomes active by providing a low-impedance path for the excessive energy, diverting it away from the protected equipment.

In summary, a lightning arrester is a vital protective device that safeguards electrical systems and structures from the destructive impact of lightning strikes and electrical surges. Its design and functionality are geared towards providing a safe discharge path for the immense energy associated with lightning events, preventing potential damage to valuable equipment and ensuring the safety of personnel.

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