A kilowatt-hour (kWh) is the amount of energy a circuit working at a kilowatt of power transfers over the course of an hour. This unit is equal to 3,600,000 joules. The kilovolt-ampere (kVA) is the power rating of a circuit carrying 1,000 volts and an ampere or 1,000 amperes and a volt. A single kilovolt-ampere is equivalent to a kilowatt. To convert from kilowatt-hours to kilovolt-amperes, you need to know only the time the circuit takes to transfer the energy.

Measure the length of time for which the circuit runs. For example, imagine a circuit that runs for 200 seconds.

Convert this value to hours by dividing by 3,600: 200 ÷ 3,600 = 0.0556 hours.

Divide the energy quantity, measured in kilowatt-hours, by this length of time. For example, if you are converting 0.25 kWh of energy: 0.25 ÷ 0.0556 = 4.496, or just under 4.5. This is the power rating in kVA.