ELECTRICAL DEPARTMENT (6TH SEM)

TOPIC : LIGHTNING ARRESTER

SUBMITTED BY :Gajendra Singh (A-50)

What is Lightning Arrester ?

• A lightning arrester, also known as lightning conductor.

• It 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 and a ground terminal.

• When a lightning surge travels along the power line to the arrestor, the current from the surge is diverted through the arrestor, in most cases to earth.

Types of Lightning Arrester

• Rod arrester• Horn gap arrester• Multi gap arrester• Expulsion type lightning arrester• Valve type lightning arrester• Silicon Carbide Arrestor• Metal Oxide Arrestor

Horn Gap Arrester

• Horn gap arrester consists of a horn shaped metal rods A and B separated by a small air gap.

• The horns are so constructed that distance between them gradually increases towards the top. The horns are mounted on porcelain insulators.

• One end of horn is connected to the line through a resistance and choke coil L while the other end is effectively grounded.

• The resistance R helps in limiting the follow current to a small value.

• The choke coil is so designed that it offers

small reactance at normal power frequency but a very high reactance at transient frequency.

• Thus the choke does not allow the transients to enter the apparatus to be protected.

• The gap between the horns is so adjusted that normal supply voltage is not enough to cause an arc across the gap.

Installation

• The arrester should be connected to ground to a low resistance for effective discharge of the surge current.

• The 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

THANK YOU