A surge arrester is a device to protect electrical equipment from over-voltage transients caused by external (lightning) or internal (switching) events. To protect a unit of equipment from transients occurring on an attached conductor, a surge arrester is connected to the conductor just before it enters the equipment.
Why lightning arresters are used?
A Lightning Arrester, Surge arrester or Line arrester is a device used on electrical power systems and telecommunications systems to protect the insulation and conductors of the system from the damaging effects of lightning. The typical Lightning Arrester has a high-voltage terminal and a ground terminal.
How does a lightning conductor protect a building from a lightning strike?
Lightning conductor a simple device used to protect tall buildings from the lightning. Lightning conductor consists of a long thick copper rod passing through the building to ground. The lower end of the rod is connected to a copper plate buried deeply into the ground.