# Transformer Calculators

Main Article: Transformers

This page contains several transformer calculators that will help you to easily calculate the transformer’s primary and secondary full-load currents, as well as the transformer type and turns ratio.

The first two calculators can be used to determine the voltage from the secondary windings; the first uses the current, and the second uses the turns ratio of the transformer.

If you need to calculate the turns ratio, the third calculator will allow you to do so.

Finally, the fourth calculator will determine the full load current of the transformer given its’ rating.

## Transformer Secondary Voltage Calculator Using Current

The following calculator will determine the voltage on the secondary windings (VS) using the values of current through the primary and secondary windings.

Enter the primary voltage (VP) as well as primary (IP) and secondary (IS)current.

The relationship between primary and secondary voltages and currents is given by the following formula:

V_S=V_P \frac{I_P}{I_S}

## Transformer Secondary Voltage Calculator Using Turns Ratio

A transformer’s turns ratio describes the number of windings (or turns) on the primary windings compared with the number of turns on the secondary windings.

The following calculator will determine the voltage on the secondary windings (VS) using the transformer turns ratio.

Enter the primary voltage (VP) as well as the turns ratio. Note that the turns ratio can be determined using the values of either voltage or current, in the next calculator on this page.

The turns ratio n is defined as the number of turns on the primary windings NP over the number of turns on the secondary windings NS:

Turns \, Ratio=n=\frac{N_P}{N_S}

The relationship between secondary voltage and turns ratio is given by the following formula:

V_S=V_P\frac{N_S}{N_P}=\frac{V_P}{n}

## Transformer Turns Ratio Calculator

The following calculator will determine the transformer’s turns ratio using either the primary and secondary voltage or current.

Select the appropriate option (either voltage or current), and enter the values as required.

The turns ratio can be found using either voltage or current via the following formula:

Turns \, Ratio=n=\frac{N_P}{N_S}=\frac{V_P}{V_S}=\frac{I_S}{I_P}

## Transformer Full Load Current Calculator

The following calculator can be used to determine the full load current of a single or three phases transformer.

Select the number of phases and enter the transformer rating in KVA as well as the primary winding voltage VP.

The full load current of a transformer can be determined by using the rating as well as the primary voltage. There are different formulas for single phase and three phase transformers.

Single Phase Transformer:

Full load current = Rating (kVA) * 1000 / VP

Three Phase Transformer:

Full load current = Rating (kVA) * 1000 / (VP * 1.732)