Preface
This is the first edition of CSA C227.5, Three-phase live-front pad-mounted distribution transformers. A previous version of this Standard was published as CAN/CSA-C227.2-88 under the title Three-Phase, Live-Front, Pad-Mounted Distribution Transformers and withdrawn in 1995. The current version includes technical and editorial changes intended to bring this Standard into line with present practice.
Scope
1.1
This Standard specifies requirements for three-phase live-front pad-mounted distribution transformer units that
(a) consist of a transformer and a separable or integral cable entrance compartment
(b) are rated 75 to 3000 kV-A and intended for operation on three-phase underground distribution systems having the preferred rated voltages specified in Tables 1 and 2
(c) are intended for mounting outdoors on pads without additional protective enclosures
1.2
This Standard does not apply to equipment involving enclosures for housing a separate three-phase transformer or a bank of single-phase transformers (see CAN/CSA-C2.1).
Note: It is possible that transformers complying with this Standard will, if operated by a body other than an electrical utility, be subject to additional requirements specified by the electrical inspection authority having jurisdiction.
1.3
This Standard allows for the replacement of a live-front pad-mounted unit by another unit of the same basic physical size from a different manufacturer without modification to cables or pad. This Standard covers terminal arrangements for both radial and loop-feed systems, including certain minimum and other dimensions.
Note: This concept should not be understood to imply that the cable entrance compartment of one manufacturer's transformer will be compatible with that of another manufacturer's transformer.
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.
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