# Interpretation of the rating of a real transformer

1. ### arpansen

4
The rating of a real transformer is 15 kVA , 2300/230-V then can we say that the primary rms is 2300 V or can we say that the secondary rms is 230 V or both.

To clarify further, suppose to solve for certain characteristics of this transformer like primary current and secondary current i use the equivalent circuit equation of the transformer referred to the primary side as:

Vp = aVs + Req*Ip + jXeq*Ip

Then what should i use for Vp or Vs in the above equation looking at the rating of the transformer.

### Staff: Mentor

Hi arpansen, welcome to the famous Physics Forums!

The primary would be 2300V and the secondary 230V. Possibly (though I'm not certain) there may be a convention that the specification follows the form primary:secondary. It would be logical to have such a convention, anyway.

In practice, I can't think of a case where a power utility would need to step up from 230 to 2300. In the event of such a rare need, I'm sure this would be clearly spelled out in the specs.

Power engineering is a very pragmatic field. You can work on the basis there's no one trying to trip you up.

Last edited: Aug 17, 2014

Usually.