This standard applies to fusion welded wrought steel enclosures pressurised with dry air, inert gas, 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 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 also covers pressurised components such as the centre chamber of live tank switchgear, gas-insulated current transformers, etc.