CAN/CSA-C227.3-M91 (R2003)

1. Scope 1.1 This Standard specifies the requirements for distribution transformers intended primarily for operation by electric utilities. Note: The operation of transformers complying with this Standard, by other than an electric utility, may be subject to additional requirements by the electrical inspection authority having jurisdiction under Part I of the Canadian Electrical Code. 1.2 This Standard covers the features of single-phase, low-profile, dead-front, pad-mounted distribution units consisting of transformer and cable entrance compartment with provision for separable insulated high-voltage connectors. Notes: (1) For details not covered herein, reference should be made to CSA Standard C2. (2) Appendix A illustrates a typical installation and cable arrangement for the purchaser who is not familiar with this type of equipment. 1.3 This Standard covers equipment intended primarily for operation on effectively grounded underground distribution systems having preferred rated voltages as shown in Table 1, and a secondary distribution voltage of 120/240 V, 3-wire. 1.4 This Standard applies to single-phase distribution transformer units having preferred kV.A capacities, at rated voltage, of 25, 50, 75, 100, and 167. 1. 5 This Standard applies to single-phase distribution transformer units intended for mounting outdoors on pads without additional protective enclosures. It does not apply to equipment involving enclosures for housing a pole-type transformer (see CSA Standard C2) and switchgear. 1.6 This Standard is intended to allow for interchangeability between pad-mounted units of the same basic physical size, but made by a different manufacturer, 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 imply that the cable entrance compartment of one manufacturer's transformer matches that of another manufacturer's transformer.