Single-Phase Submersible Distribution Transformers, Type ONAN
This Standard covers the features of single-phase submersible transformers. For other details, reference shall be made to CSA Standard C2, Single-Phase and Three-Phase Distribution Transformers Types ONAN and LNAN, hereinafter referred to as CSA Standard C2.
See Appendix A, Recommendations for Corrosion Control of Submersible Transformer Installations, which covers recommended practices for handling and installation, cathodic protection, and ma intenance to ensure an acceptable service life.
The rated kVA capacities at rated voltage shall be 25, 50, 75, 100 and 167.
This Standard applies only to single-phase distribution transformer units intended for use in a ventilated vault or enclosure below grade level. It does not apply to directly buried transformers in contact with the earth, or to permanently submerged transformers.
The transformers covered by this Standard are intended for operation only by electrical utilities on effectively grounded underground distribution systems having primary voltages up to and including 16.0/27.6 kV grounded Y. The transformer secondary voltage will normally be 240/120 volts, 3-wire. Other secondary voltages in accordance with CSA Standard C2, 1.2 kV class may be provided at the request of the purchaser.
The equipment covered by this Standard normally has dual HV bushings designed for circuit loop feed within the transformer tank. High-voltage protection normally connected between this internal loop feed element and the transformer HV winding is not covered by this Standard and should be specified by the purchaser.
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 approp riate electrical inspection authority.