CSA C50052:24

1.1 Scope [ Replace this clause with the following] This Standard applies to cast aluminium alloy enclosures pressurized with dry gases and gas mixtures (see Note 1) used in indoor or outdoor installations of high-voltage 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 circuit-breakers (T unit).