scope:

This standard applies to welded composite enclosures of cast and wrought aluminium alloy enclosures pressurized with dry air, inert gases, for example sulphur hexafluoride or nitrogen or a mixture of such gases, used in indoor or outdoor installations of high-voltage switchgear and controlgear with rated voltages of 72,5 kV and above, where the gas is used principally for its dielectric and/or arc-quenching properties. The enclosures comprise parts of electrical equipment not necessarily limited to the following examples: - circuit breakers; - switch disconnectors; - disconnectors; - earthing switches; - current transformers; - voltage transformers; - surge arrestors; - busbars and connections. The scope covers also pressurized components such as the centre-chamber of live tank switchgear and controlgear, gas-insulated current transformers, etc.