Transformer

From input to answer.

Open All Tools → Transformer.
Choose Single phase or Three phase, then the quantity to solve for.
Enter the known kVA, primary voltage and secondary voltage, or the appropriate current for the selected solve mode.
Read primary current, secondary current and voltage ratio. Check that you entered values for the correct side.

WORKED EXAMPLE

A 75 kVA three-phase transformer

Enter

Choose three phase and primary current. Enter 75 kVA, 600 V primary and 208 V secondary.

Read the result

Primary current is about 72.17 A; secondary current is about 208.18 A. The voltage ratio is about 2.885:1.

Get more from it.

kVA is apparent power. Do not substitute kW without considering power factor.
Three-phase voltage entries are line-to-line values.
The displayed voltage ratio is not necessarily a winding turns ratio for a three-phase delta/wye connection.

Know the limits.

Ideal steady-state relationships; losses, voltage regulation, inrush and fault current are not calculated.
Current results do not select protection, bonding or conductor ampacity.

Verify the inputs, applicable local requirements and real conditions. The app is a calculation aid and can contain errors. See our terms and safety disclaimer.

Common questions.

Can I solve from a known current?

Yes. Select the quantity and side that match the values you know, then use the input labels shown.