CSA C199-08:2017 pdf download.Three-phase network distribution transformers
1.1 CSA C199-08 specifies the mechanical and electrical characteristics of three-phase network distribution transformers having rated primary voltages up to 34.5 kV and kV●A ratings of 500 to 2500.
Note: It is possible that transformers complying with this Standard will, if operated by a body other than an electric utility,be subject to additional requirements imposed by the electric inspection authority having jurisdiction.
1.2 This Standard applies only to three-phase distribution transformer units intended for use in a ventilated vault or enclosure below grade level.
1.3 The equipment covered by this Standard is primarily intended for operation by electric utilities on effectively grounded underground distribution systems.
1.4 In CSA Standards, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; "should" is used to express a recommendation or that which is dvised but not required; "may" is used to express an option or that which is permissible within the limits of the standard; and "can" is used to express possibility or capability. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.
5.5.2 High-voltage connection shall be provided for use with separable insulated connectors or lead-covered cables as follows:
(a) Separable insulated connectors: in accordance with IEEE 386; and
(b) Lead-covered cables: suitable submersible entrance fittings shall be located on top of the terminal chamber. Wiping sleeves, where applicable, shall be made of brass, bronze, or copper.
There shall be a raised base around openings on horizontal surfaces so that the lower edge of the gasket is located 6 mm above the surface.
5.5.3 The high-voltage bushings between the transformer tank and switch chamber shall be sealed to prevent interchange of liquid between compartments. The insulators of the bushings shall be replaceable from the switch chamber without removing the core and coil assembly from the tank.
5.5.4 When a terminal chamber is required, the high-voltage bushings between the terminal chamber and the switch chamber shall be sealed to prevent interchange of liquids or compounds between compartments (see Figures 4 and 5). Bushings shall be of the stud or blade type and the distance from the stud or blade to the liquid level shall be as shown in Figures 4 and 5.CSA C199-08 pdf download.