**Transformer Nameplate Rating:**

Transformer Nameplate Rating Details – The voltage ratio is specified as V_{1} (rated)/V_{2} (rated). It means that when voltage V_{1} (rated) is applied to the primary, the secondary voltage on full load at specified pf is V_{2} (rated).

The ratio V_{1} (rated)/V_{2} (rated) is not exactly equal to N_{1}/N_{2}, because of voltage drops in the primary and secondary. These drops being small are neglected and it is assumed that for all practical purposes

The rating of the transformer is specified in units of VA/kVA/MVA depending upon its size.

where *V* and *I* are referred to one particular side. The effect of the excitation current is of course ignored.

The Transformer Nameplate Rating also specifies the equivalent impedance, but not in actual ohm. It is expressed as the percentage voltage drop expressed as

where all quantities must be referred to any one side.