To create a transformer, go to
Ribbon: DM Electrical->Distribution Equipment-> 
Transformers
Pulldown Menu: DM Electrical->Distribution Equipment->Transformers
Transformer Dialog Box
See the Common Schedule Dialog Box Features section for more information about how this dialog box works. This section describes the Rename, Find, Previous, Next, New, Copy, Save, and Delete buttons.
KVA: The kVA rating of the transformer.
K-Rated: Whether the transformer is K-rated. The value of this setting can be displayed on the distribution equipment schedule. It is for informational purposes only and is not otherwise used.
See the Distribution Equipment Dialog Box Settings section for more information about the other values and buttons in this dialog box.