This document applies to wrought steel enclosures and their welding. These enclosures are pressurized with dry air, inert gases, for example sulphur hexafluoride or nitrogen or a mixture of such gases, used in indoor and outdoor installations of high-voltage switchgear and controlgear with rated voltages above 1kV , where the gas is used principally for its dielectric and/or arc-quenching properties with rated voltages:
The enclosures comprise parts of electrical equipment not necessarily limited to the following examples:
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circuit-breakers;
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switch-disconnectors;
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disconnectors;
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earthing switches;
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current transformers;
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voltage transformers;
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surge arrestors;
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busbars and connections;
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etc.
The scope also covers enclosures of pressurized components such as the centre chamber of live tank switchgear, gas-insulated current transformers, etc.