||-> The surge arrester shall be designed and constructed in accordance with IEC 60099-4 and the requirements of this specification. It shall be suitable for overvoltage protection of distribution networks.
-> The metal-oxide used shall be of quality to ensure thermal stability under service duty of the surge arrester.
-> The arrester shall be single column, self supported and be installed between phase and earth.
-> The housing of the surge arrester shall be made of high quality silicone rubber of the following minimum properties:
b) insensitivity to ultra-violet radiation
c) excellent tracking resistance
d) excellent mechanical impact, abrasion and shear resistance
e) excellent long-term stability and resistance to ageing under climatic and electrical stresses.
Porcelain type surge arresters are accepted for the 20kA rating.
-> The surge arrester shall be sealed (end caps) with a controlled permanent seal to ensure no moisture absorption or deterioration of the metal-oxide element of the surge arrester.
-> The surge arrester shall be designed and constructed in a manner so as to prevent explosive shattering of the housing in the event of the arrester failure. Pressure relief device (with indicator) shall be fitted on the porcelain type surge arresters (20kA rating).
-> The surge arrester shall be supplied complete fitted with a mechanical fault indicator. Details on the operation shall be submitted with the offer.
-> The surge arrester shall be supplied complete with mounting bracket, fixing accessories and clamp connector suitable for both copper and aluminium conductors of up to 12.5mm diameter. All parts shall be protected against corrosion.The mounting brackets for distribution class surge arresters shall be suitable for both horizontal and vertical mounting on a steel crossarm (U-channel). Station class surge arrester, when required, shall be suitable for pedestal mounting with pitch circle diameter of 76mm.