Metal Oxide Surge Arrester
metal oxide surge arrester (MOA) which consist of a series connected stack of discs of zinc oxide elements, operates in a very simple fashion. The methods of predicting the operation and performance of the metal oxide arresters in power system application deal with:
(a) The low current V-I characteristics of the arrester for non-adiabatic thermal behavior.
(b) The high current V-I characteristics for response to surges and system disturbances.
The metal oxide technology opens many opportunities for arrester’s application in adverse operating and atmospheric conditions where gap-type arresters could not be used. It is constructed by a series connection of zinc oxide (ZnO) elements having a highly non-linear resistance. The excellent non-linear characteristic of zinc oxide element has enabled to make surge arresters without series connected spark gaps, i.e. fully Solidstate arresters suitable for system protection up to the highest voltage. The metal oxide surge arrester (MOA) which consists of a series connected stack of discs of zinc oxide elements operates in a very simple fashion.
The application of the metal oxide arresters include:
(a) Suppression of switching surge voltage.
(b) Absorption of large amounts of energy.
(c) Application in the presence of large temporary overvoltage.
Thermal stability criteria for metal oxide surge arresters. The thermal stability of a metal oxide surge arrester is defined by its heat loss input balance criteria.
Metal Oxide Surge Arrester Advantage
(1) Series spark-gap is not required.
(2) A very small time delay in responding to overvoltages.
(3) Superior protective performance.
(4) It has a very simple construction and is a fully solid-state protective device.