Lighting Arrester or Switching Surges
Lightning arrester is a protective device which is give protection against the over voltage due to the lightning surges. A Device Used on Power Systems above 1000V to Protect other Equipment from Lightning and Switching Surges.
Lightning is the most frequent cause of over voltages on distribution systems. Basically, lightning is a gigantic spark resulting from the development of millions of volts between clouds or between a cloud and the earth.
Explanation of a Lightning: The duration of the lightning stroke is usually less than a couple of hundred microseconds.
- Lightning Rods are devices that divert lightning surges to ground, they are simple conductive terminals that are always at ground potential and are never energized. lightning incidence is high, but no lightning rod can offer absolute protection.
A lightning rod protection system has three main parts:
- The rods on the top of the protected structure.
- The wires which connect the rods together and those which run down the sides of the structure to the grounding arrangement.
- The grounding arrangement.
To protect high voltage transmission lines from lightning, the metallic rods and wire conductors are replaced by a system of wires.
What exactly does a lightning arrester do?
- It is not Absorb the Lightning
- It is not Stop the Lightning
- Divert the Lightning to Ground
- It is Clamp (limit) the Voltage produced by the Lightning
- Only protects equipment electrically in parallel with it.
Installation of Lighting Arrester
- The Lighting Arrester should be mounted close to the equipment to be protected & connected with shortest possible lead on both the line & ground side to reduce the inductive effects of the leads while discharging large surge current.
- The Lighting Arrester should be connected to ground to a low resistance for effective discharge of the surge current.
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