How to Calculate the Rating of a Transformer in kVA

How to Calculate the Rating of a Transformer in kVA

Steps for selecting the correct kVA transformer

Selecting the correct transformer kVA rating is important. You need to ensure the standard kVA capacity is equal to or greater than the required operating load. There are two equations for calculating transformer kVA ratings, depending on if it’s a single phase or three phase transformer.

Selecting a single phase transformer

To determine the single phase transformer you need, there are a few other things which need to be considered.

Determining the electrical load requires you to know the voltage and amperes or kVA capacity required by load. You will also need to know the supply voltage and frequency.

Transformers can be manufactured with primary taps which allow variations in line voltage. This allows the user more opportunities once the transformer is operational.

All this information is on a transformer’s rating plate, if a direct replacement is needed. Should you not know this information or need some advice give us a call and we can talk you through what you will need. Call our team on 0151 486 6760.

Selecting a three phase transformer

Three phase transformers are similar to single phase transformers, however they have 3 sets of windings. Three phase transformers can be connected in either star or delta configuration. This is dependent upon how the sets of windings are interconnected.

In case you are not familiar with those configurations, you can contact us to discuss your requirements. Call us on 151 486 6760.

  delta star transformer

How to work out a transformer’s kVA rating.

Transformers are usually rated by kVA. There is a few simple formulas which will help you work this out.

Find the rating of a single phase transformer

Rating of single phase transformer: P = V x I

Rating of a single phase transformer in kVA: kVA = (V x I)/1000

Find the rating of a three phase transformer

Rating of three phase transformer: P = √3 V x I

Rating of a three phase transformer in kVA: kVA = (√3 V x I) / 1000

Call us

Our team are here to help with any questions you may have so please call us on 0151 486 6760. To view our transformer range please click here

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