CSA C199-08 pdf download – Three-phase network distribution transformers.
1 Scope 1.1 This Standard 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 advised 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.
3 Definitions The definitions listed in Clause 2.2 of CAN/CSA-C2.1 and the following definition apply in this Standard: Network distribution transformer — a transformer designed to feed a variable-capacity system of interconnected secondaries of transformers supplied by individual primary sources. 4 General requirements 4.1 Unless otherwise specified in this Standard, the requirements pertaining to electrical and mechanical characteristics and to tests specified in CAN/CSA-C2.1 shall apply to three-phase network distribution transformers. 4.2 Three-phase network distribution transformers and their accessories shall be categorized as follows with respect to conditions of operation: (a) Category 1 : intended for operation in normal outdoor exposures and in dry vaults; and (b) Category 2: intended for operation while partially or totally submerged, or under corrosive conditions due to sewage and street or salt water. The purchaser shall specify which category is required. 4.3 Three-phase network distribution transformers shall be capable of operating at an angle of 2° maximum in any direction from a level position. 5 Mechanical characteristics and transformer accessories 5.1 General requirements for tanks 5.1.1 Transformer tanks shall have a sealed construction, with the main cover welded in place. The cover shall have an access opening and a suitable means for lifting during cover removal. A bolted cover may be provided when specified by the purchaser (see Clause 1 2(h)).
5.2.2 There shall be a ring around the access opening so that the underside of the cover is located at least 6 mm above the main cover. 5.2.3 The opening, if circular, shall be at least 300 mm in diameter and, if rectangular, shall have minimum dimensions of 250 × 300 mm. The access opening shall be located in such a way that the neutral ground connection can be disconnected for performing the tests specified in Clause 1 0. 5.3 Exterior finish of tank 5.3.1 Tanks for Category 1 transformers shall have an exterior finish that meets the requirements of IEEE C57.1 2.28. 5.3.2 Tanks for Category 2 transformers shall have an exterior finish that meets the requirements of IEEE C57.1 2.28, except that the duration of the salt spray test shall be 2500 h. A special anti-corrosion finish shall be applied. In addition, an asphalt-saturated or similar coating shall be applied to the tank bottom and extended up the tank sides to a point 300 mm above the bottom, but not less than 25 mm above the topmost surface of the bottom entrance of the cooling tubes. 5.3.3 Tanks shall be painted ANSI 70 grey unless otherwise specified by the purchaser. 5.4 Moving facilities 5.4.1 Tanks shall be provided with four lifting lugs that can accommodate a 25 mm clevis, a sling, or both, so that the complete unit can be lifted in a properly balanced manner.CSA C199-08 pdf download.
