What is lightning arrester？
A lightning arrester is a device used on electric power transmission and telecommunication systems to protect the insulation and conductors of the system from the damaging effects of lightning.
What is metal oxide varistor lightning arrester?
Metal oxide varistor(MOV) lightning arrester (also know as zinc oxide lightning arrester) is a type of arrester which uses zinc oxide semiconductor as a resistor material.
The MOV lightning arrester has een taking the place of the conventional gapped arresters on a world-wide scale. So in this article, we will focus on the discussion of the mov lightning arrester.
What types exist?
- Classified by its housing manufacturing materials, we have polymer type and porcelain type.
- Classfied by energy handeling capability, we have:
Class 1 – 10,000 Amp Nominal Discharge Current /Distribution Class
Class 2 – 10,000 Amp Nominal Discharge Current/ Distribution Class/Intermediate
Class
Class 3 – 10,000 Amp Nominal Discharge Current, Ur < = 420 kV/Station Class
Class 4 – 20,000 Amp Nominal Discharge Current, Ur <= 420 kV/ Station Class
Class 5 – 20,000 Amp Nominal Discharge Current , Ur >360 kV/ Station Class
- By application, there are:
Transmission line
Substation
GIS
HVDC
Railroad, generator, motor, reactor, capacitor and SVC protection
What other elements are needed(optional for polymer lightning arrester )?
- Dust-proof cap
- Surge counter monitor
- Mounting bracket
- Disconnector
What elements make up a lightning arrester?
The components of a lightning arrester are:
- Zinc oxide varistor element
- Porcelain housing/polymer housing
- End fitting( line terminal and ground terminal)
- Other optional accessories
why should we use a lightning arrester?
The metal oxide surge arrester has the following merits:
It eliminates the risk of spark over and also the risk of shock to the system when the gaps break down.
It eliminates the need of voltage grading system.
At the normal operating condition, the leakage current in the ZnO is very low as compared to other diverters.
There is no power follow current in ZnO diverter.
It has high energy absorbing capability.
ZnO diverters possess high stability during and after prolonged discharge.
In ZnO diverter, it is possible to control the dynamic overvoltages in addition to switching surges. This results in economic insulation coordination.
