# Interpretation of rating of the primary voltage of a real transformer [duplicate]

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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.

In the above equation looking at the rating data given above is Vp= 2300 or Vs = 230 ?As mentioned earlier the transformer is mentioned to be real.

## marked as duplicate by jippie, PeterJ, placeholder, Vladimir Cravero, Andy akaAug 17 '14 at 17:38

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• How is this question different from the other one? – jippie Aug 17 '14 at 13:43

## 1 Answer

The kVA rating is a measurement of power for the transformer (volts x amps) without taking the phase angle into consideration.

The 2300/230 signifies the transformer ratio (primary/secondary). A 2300V (rms) input should give a 230V (rms) output.

Assuming the transformer is 100% efficient then the volt*amp products of the primary or secondary should be the same. However, in the real world, the secondary power (out) will be less than the primary (in). So taking the worst case senario then use the primary product (2300 * I(in)) = 15 000 giving a max input current of 6.52 amps.