CSA C227.4-M1978 (R2005)

This PDF includes Errata #1.

1. Scope

1.1

This Standard covers the features of three-phase dead-front pad-mounted distribution units consisting of transformer and cable entrance compartment with provision for separable insulated high-voltage connectors. For other details, reference s hall be made to CSA Standard C2, Single-Phase and Three-Phase Distribution Transformers, Types ONAN and LNAN.

1.2

The rated kVA capacities at rated voltage shall be 75, 150, 225, 300, 500, 750, 1000, 1500, 2000, and 2500.

1.3

This Standard applies only to three-phase distribution transformer units intended for mounting outdoors on pads without additional protective enclosures. It does not include equipment involving enclosures for housing a separate three-phase transformer or a bank of single-phase transformers (see CSA Standard C2), or switchgear.

1.4

The equipment covered by this Standard is primarily intended for operation by electric utilities on three-phase underground distribution systems having primary voltages as shown in Table 1.

1.5

When this equipment is intended for operation by other than an electric utility, it shall be the purchaser’s responsibility to ensure that the unit meets the requirements of the appropriate electrical inspection authority.

1.6

This Standard is intended to provide for the replacement of a dead-front pad-mounted unit by another of the same basic physical size from a different manufacturer without modifications to cables or pad. This Standard covers terminal arrangements for both radial and loop-feed systems, including certain minimum dimensions and certain specific dimensions. However, this Standard does not imply the matching of one manufacturer’s transformer with another manufacturer’s cable entrance compartment.