How to Figure KVA of a Transformer: Transformer KVA Calculator

A transformer is used to change the voltage level of voltage. The transformers are of two types, step up and step-down transformer. A transformer can be selected based on the following parameters a) Power rating (kVA) b) Primary Voltage (Vp) c) Secondary Voltage (Vs) and d) Tapping arrangement. Learn how to figure KVA of a transformer by using the online Transformer KVA Calculator.

Transformer KVA Calculator

Put the type of transformer, power rating in KVA, Voltage in volts, and Current in amperes to calculate the other parameters. Put only two parameters to calculate the third parameter and select the type of transformer.

Transformer Type

Power Rating, (kVA)

Voltage, V(v)

Current, I(amp)

The KVA calculation is based on the voltage and amperage of the transformer. The KVA of the transformer is the same primary and secondary sides. The single-phase transformer KVA calculation can be as the following formula.

$KVA = V \times I $

For a three-phase transformer the KVA calculation can be as the following formula.

$KVA = \frac{\sqrt{3}\times V \times I}{1000}$

Where the V is the voltage, and I is the current of the transformer.

Transformer KVA calculator

Why Transformer Rating is in KVA Not in KW?

Manufacture design and produce a transformer for a specific range of current and voltage. And that specific range of voltage and current may produce certain losses in the transformer. When a different load is connected to the transformer it may work on different power factors. And for different KW loads, the current and voltage could be the same. Alternatively, KW cannot tell you exactly about the current of the transformer but KVA can. Where the transformer losses all depend upon the current of the transformer.

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