Converting kVA (kilovolt ampere) to a 3-phase kW (kilowatt) reading when kilo is equal to 1000 can be performed by executing a formula. This formula can be applied for home emergency generator sets or an industrial motor electrical application. By following a set of multiplication rules and knowing the power factor of the 3-phase device you can calculate this conversion.
Understand the above-listed formulas. Essentially, the kVA equation is for the potential of the electrical circuit. This means the electrical circuit can provide this much power to the motor or device. The kW equation will give the actual power used by the device or motor since the power factor of the motor is multiplied into the formula. The power factor typically is listed on the identification nameplate of most larger electrical motors that use a 3-phase power.
Calculate the kVA of an electrical circuit that has the potential of 480 volts at 50 amperes: 1.73 x 480 x 50 = 41,520 VA. Note that the answer is in VA (volt amperes), not kVA. We must divide the VA value by 1000 to convert to kVA: 41,520 divided by 1000 = 41.52 kVA.
Find the kW rating or consumption of the 3-phase circuit using the power factor identified on the nameplate of the motor or device. For example, if the listed power factor is 0.8, the calculation is: 41.52 (kVA) x 0.8 = 33.216 kW.
Simplify the conversion to a single calculation, using the same values: kW = 1.73 x 480 (volts) x 50 (amperes) x 0.8 (power factor)/1000 = 33.216.
TL;DR (Too Long; Didn't Read)
Readings for motors should be taken with a hand-held ammeter for accurate amperage calculations when performing a kW equation. Nameplate amperage ratings can vary from actual motor usage.