Difference between Surge Arrester, Lightning Arrester and Lightning Rod

Difference between Surge Arrester, Lightning Arrester and Lightning Rod:

Surge arrester is used to protect the circuit or electrical equipment from high voltage transient or electrical surges. Lightening causes 1000kV + Voltages rises on the power line. It may damage the electrical equipment. In order to avoid this, the surge arresters are normally used.

Lightning arrester works like surge arrester from outside of the conductor. They absorb the electrical surges in the transmission tower itself.

Lightning rod is a pre protection device. Which absorb the lightning before fall in to the transmission line.


Surge arrester:

Purpose of Surge arrester
Purpose of Surge arrester
  • Surge arrester participate inside of the power line. Which means the surge arrester will be installed in the transmission line, the total power system phase voltage is directly applied across the surge arrester.
  • The surge arrester will be installed nearer to the equipment to be protected and the transmission tower line enter in to the substation point. In the diagram has shown the surge arrester has installed near to the transformer.
  • It protects against high voltage transient (example: lightning strike on the transmission conductor) typically, it is indirect protection of lightning strikes.
  • It should be installed each phase of the circuit. i.e if you have 2 parallel switch yard then you should install 6 number of lighting arrester (first run 3 phase and second run 3 phase) .
  • Surge arrester are very costlier device.
  • Surge arrester protects the power system, even the system voltage is high without lightning strike.
  • It is just works under principle of varister. Varister is nothing but s voltage dependent resister whose resistance will be varied when the voltage changes across it. For small equipment it is named as MOV (metal oxide varister)
  • The number of operating time can be counted

Note: Guys Do not confuse between the lightning rod and lightning arrester.

Lighting arrester:

Purpose Lightning arrester
Lightning arrester

Lighting arrester is used to suppress the high transient voltage, isolation arc, electrical surge currents from spark and lightning currents from lightning strikes.

  • The lighting arrester is doing the exact duty of surge arrester from outside of the conductor.
  • The lightning arrester does not have any contact with the power line conductor.
  • They will be installed in the transmission tower.
  • They are attached with the insulator or separately placed nearer to the conductor and the end terminal is connected with the ground.
  • Refer the figure that the current flow path during the lightning strike on the conductor.

Lightning arrester replacement on 220kV:

Lightning arrester replacement
Lightning arrester replacement

Purpose of lightning Rod:

lightning rod
lightning rod

Lighting is nothing but a sudden electrostatic discharge between the cloud and earth. If, they fall on the transmission lines means the system voltage might be elevated to dangerous voltage level. Hence these lightning strike should be avoided falling on the transmission line. To protect the electrical equipment from lighting (before falling on to the transmission line), the lightning rods are used.

  • Lightning rods are installed on the highest point on the structure typically top floor on the building, top end of the transmission tower, top of the chimney etc.
  • It protects the equipment from the direct lightning strikes.
  • They capture the lightning charges and connect it with the ground.
  • The lightning rods are made up of with the copper bus bar or conductor which laid from the top of the structure to bottom of the ground. The bottom end of the lightning conductor should be earthen to flow the lightning current. You must see the earthing procedure here.
  • Very less cost as compare with surge arrester.
  • Lightning rod must be divided for at the top end to absorb the high lightning current.

The above points may help you to identify Difference between Surge Arrester, Lightning Arrester and Lightning Rod

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