Transformer Sizing Calculator

Our transformer size calculator can find the right transformer size (single or three-phase) for any load you require!

Within this short text, you will learn:

• The working principle of transformers;
• How to size a single-phase transformer;
• How to calculate transformer size for a three-phase transformer; and
• More!

Keep reading to learn about all the features of this transformer kVA calculator.

Transformers are electrical devices that transform voltages. They can bring the voltage up or down depending on their purpose.

Transformers work in the following way:

1. Alternating current (AC) flows through a coil of wire, producing a changing magnetic field.
2. A magnetic core leads this magnetic flux through another coil of wire which has a different number of turns than our first coil.
3. Electromagnetic induction produces an electromotive force, a voltage difference, on the second coil.
4. According to the number of turns, this transformer will create a step-up or step-down in voltage.

We size transformers based on the load they should power and use kVA, kilo volt-ampere, to rate them (what is kVA?). A higher transformer's kVA means a higher current and voltage output.

To find the appropriate size for our load, we need two things:

• $I$, the current of our load; and
• $V$ our load's voltage requirement.

Then, all we need to do is plug these parameters into the respective transformer formula.

For a single-phase transformer, we have:

and for a three-phase transformer:

Using this tool is straightforward:

1. Select the type of transformer (single or three-phase).
2. Input your load's current requirement.
3. Input your load's voltage requirement.
4. Our calculator will automatically output the minimum kVA rating for the transformer. Give it a try!