Calculating Power Consumption

To calculate power consumption

KVA x power factor = kilowatts

KW x hours used x cost per kwh

Add 1 phase and 3 phase together.

If you don't have actual voltage, you should at least be able to get nominal voltage of both load types from equipment nameplates. A good estimate of apparent power (KVA) can be obtained using the procedure shown below.

For the 3ph system, calculate the average current for all 3 phases:

(I₁ + I₂ + I₃)/3 = I_average

Using average current and nominal voltage, calculate 3ph KVA:

(V_nominal3ph x I_average x 1.732)/1000 = KVA_3ph

For the 1ph system, use the measured current and nominal voltage to calculate 1ph KVA:

(V_nominal1ph x I_1ph)/1000 = KVA_1ph

The total apparent power used is the sum of the 3ph and 1ph power flows:

KVA_total = KVA_3ph + KVA_1ph