 # How to Calculate the Rating of Single Phase & Three Phase Transformers in kVA

The rating of a transformer is the maximum amount of power that it can deliver to the load.

It is expressed in kVA (kilovolt-amps), which is the product of the voltage and current in the transformer.

The rating of a transformer depends on the number of phases, the primary and secondary voltages, and the primary and secondary currents.

To calculate the rating of a single phase transformer, you can use this formula:kVA = (V x I) / 1000where V is the voltage (in volts) and I is the current (in amps) on either the primary or secondary side of the transformer.

For example, if you have a single phase transformer with a primary voltage of 120 V and a primary current of 10 A, you can find its rating by multiplying 120 x 10 and dividing by 1000.

The result is 1.2 kVA.To calculate the rating of a three phase transformer, you can use this formula:kVA = (√3 x V x I) / 1000where √3 is the square root of 3 (approximately 1.732), V is the line-to-line voltage (in volts) and I is the line current (in amps) on either the primary or secondary side of the transformer.

For example, if you have a three phase transformer with a primary line-to-line voltage of 480 V and a primary line current of 20 A, you can find its rating by multiplying √3 x 480 x 20 and dividing by 1000.

The result is 16.6 kVA.You can also use online calculators to find the rating of transformers, such as [this one](^5^). You just need to enter the number of phases, the voltage and the current, and it will give you the kVA rating.