CSA C227.3:25 ✓ Most Recent

Preface 

This is the fifth edition of CSA C227.3, Low-profile, single-phase, pad-mounted distribution transformers with separable insulated high-voltage connectors . It supersedes the previous editions published in 2006, 1991, 1979, and 1974. Changes to this edition include updates to various clauses, tables, figures, and annexes to reflect minimum industry requirements. CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support of Alectra Utilities, Electricity Canada (EC), EPCOR, FortisAlberta, FortisBC, Hydro One, Hydro-Québec, IFD Corp., K-Line Insulators Ltd., Maritime Electric, NB Power, Newfoundland and Labrador Hydro, Newfoundland Power, Nova Scotia Power, S&C Electric Canada Ltd., Schneider Electric Canada Inc., Toronto Hydro, and Utilities Standards Forum (USF). This Standard was prepared by the Subcommittee on Overhead and Pad-Mounted Distribution Transformers, under the jurisdiction of the Technical Committee on Distribution Transformers and the Strategic Steering Committee on Power Engineering and Electromagnetic Compatibility, and has been formally approved by the Technical Committee. This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. 

Scope 

1.1 This Standard specifies the requirements for single-phase, pad-mounted distribution transformers with separable insulated high-voltage connectors and is intended primarily for operation by electric utilities. Note: The operation of transformers complying with this Standard by other than an electric utility can be subject to additional requirements by the electrical inspection authority having jurisdiction. 

1.2 This Standard applies to single-phase, pad-mounted, 60 Hz, liquid-filled distribution transformers with separable insulated high-voltage connectors designed for operating on an effectively grounded wye system, rated at 167 kVA or below, up to 27.6 kV system voltage, and suitable for mounting outdoors on pads without additional protective enclosures. 

1.3 This Standard includes voltage ratings, kilovolt-ampere ratings, certain mechanical characteristics, and test procedures. This Standard also includes the following performance characteristics: energy efficiency (in accordance with CSA C802.1), temperature rise, loading capabilities, sound level, and radio influence voltage (RIV). 

1.4 This Standard covers equipment intended primarily for operation on effectively grounded underground distribution systems having preferred rated voltages as shown in Table 1and a secondary distribution voltage of 240/120 V, three-wire. 

1.5 This Standard is intended to allow for interchangeability between pad-mounted units of the same basic physical size but made by different manufacturers, without modifying the cables or the pad. This Standard covers terminal arrangements for a loop-feed system, including certain minimum dimensions and certain specific dimensions, but does not ensure that the cable entrance compartment of one manufacturer’s transformer matches that of another. Note: When this equipment is intended for operation by other than an electric utility, it is the purchaser’s responsibility to ensure that the unit meets the requirements of the appropriate electrical inspection authority. 

1.6 In this Standard, "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; and "may" is used to express an option or that which is permissible within the limits of the Standard. 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.