CSA C50069:24

1 Scope This Standard applies to gas-filled welded composite enclosures of cast and wrought aluminium alloys pressurized with dry gases and gas mixtures (see Note 1) used in indoor or outdoor installations of highvoltage switchgear and controlgear, where the gas is used principally for its dielectric or arc-quenching properties, with rated voltages – of 1 kV and up to and including 52 kV, and with gas-filled compartments with design pressure higher than 300 kPa relative pressure (gauge); and – above 52 kV. NOTE 1 See IEC 62271-4 for information regarding gases and gas mixtures used in high-voltage switchgear and controlgear. NOTE 2 Examples of dry gases and gas mixtures used in high-voltage switchgear and controlgear include, but are not limited to, SF6, SF6/N2; SF6/CF4; compressed air, natural-origin gases and their mixtures (N2, O2 CO2), C5F10O (C5-FK, fluoroketone) in mixtures with N2, CO2, O2 (C5-FK mixtures) and C4F7N (C4-FN, fluoronitrile) in mixtures with N2, CO2, O2 (C4-FN mixtures). 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 arresters; and – busbars and connections. The scope also covers enclosures of pressurized components. NOTE 3 One example of such components is the centre cast-aluminum enclosure of live tank circuitbreakers (T unit).