What is Lighting Arrester? Working Principle of Lighting Arrester?

Lighting Arrester

Lightning can create voltage surges in several of the subsequent ways. Lightning can score an instantaneous hit on your house. It can strike the overhead cable which enters your house, or a main cable that's blocks faraway from your home. Lightning can strike branch circuitry wiring within the walls of your house. Lightning can strike an object near your home like a tree or the bottom itself and cause a surge. Voltage surges will be created by cloud to cloud lightning near your home. A highly charged cloud which passes over your home may also induce a voltage surge.

Voltage surges also can be caused by standard on and off switching activities of huge electric motors or pieces of kit. These surges are often created by a neighbor, or by a business or manufacturing facility a ways from your house. These surges are insidious and for the foremost part are silent. they'll occur with little or no warning.

 Working Principle of Lighting Arrester :

The earthing screen and ground wires can well protect the electrical system against direct lightning strokes but they fail to supply protection against traveling waves, which can reach the terminal apparatus. The lightning arresters or surge diverts provide protection against such surges. A spike arrester or a surge diverted could be a protective device, which conducts the high voltage surges on the ability system to the bottom.

The earthing screen and ground wires can well protect the electrical system against direct lightning strokes but they fail to produce protection against traveling waves, which can reach the terminal apparatus. The lightning arresters or surge diverters provide protection against such surges. A suppressor or a surge diverted could be a protective device, which conducts the high voltage surges on the ability system to the bottom.

Lighting Arrester

Fig shows the essential kind of a surge diverter. It consists of a spark gap nonparallel with a non-linear resistor. One end of the diverter is connected to the terminal of the equipment to be protected and therefore the other end is effectively grounded. The length of the gap is so set that ordinary voltage isn't enough to cause an arc but a dangerously high voltage will break down the air insulation and form an arc. The property of the non-linear resistance is that its resistance increases because the voltage (or current) increases and vice-versa. this is often clear from the volt/amp characteristic of the resistor shown in Fig

The action of the surge protector or surge divert er is as under:

(i) Under normal operation, the spike suppressor is off the road i.e. it conducts no current to earth or the gap is non-conducting

(ii) On the occurrence of over voltage, the air insulation across the gap breaks down and an arc is created providing an occasional resistance path for the surge to the bottom. during this way, the surplus charge on the road because of the surge is harmlessly conducted through the arrester to the bottom rather than being sent back over the road.

(iii) it's worthwhile to say the function of non-linear resistor within the operation of arrester. because the gap sparks over thanks to over voltage, the arc would be a short-circuit on the ability system and should cause power-follow current within the arrester. Since the characteristic of the resistor is to supply low resistance to high voltage (or current), it gives the effect of short-circuit. After the surge is over, the resistor offers high resistance to form the gap non-conducting.


Type of Lighting Arrester for Outdoor Applications:

There are several varieties of lightning arresters normally use. They differ only in constructional details but treat the identical principle, providing low resistance path for the surges to the round.

1. Rod arrester

2. Horn gap arrester

3. Multi gap arrester

4. Expulsion type suppressor

5. Valve type suppresser

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