Power Consumption formula
Power Consumption formula
(OP)
Hi,
Can anyone help clear the air, I am trying to calculate the total KVA demand from a set of reading i took from a 3-phase supply. I used a power quality meter to record the max current reading from each phase. 120A 140A 143A, i am trying to convert the reading to a total KVA demand but having trouble with my figures. Assuming that power factor is around 85%. Please could some help with the formula.
Thanks
Can anyone help clear the air, I am trying to calculate the total KVA demand from a set of reading i took from a 3-phase supply. I used a power quality meter to record the max current reading from each phase. 120A 140A 143A, i am trying to convert the reading to a total KVA demand but having trouble with my figures. Assuming that power factor is around 85%. Please could some help with the formula.
Thanks






RE: Power Consumption formula
For three-phase circuits, kVA = kV x Current x 1.732 (where kV is line-to-line voltage). You would use the average of the three currents. Or you can calculate on a per-phase basis, using the line to neutral voltage times the current and simply add the three kVA values together.
If you are interested in kVA, the power factor is irrelevant. If you are interested in kW, you need to do a little basic review of electrical power concepts.
None of this is going to tell you the "demand" as generally defined in the electrical power community.
David Castor
www.cvoes.com
RE: Power Consumption formula
RE: Power Consumption formula
Make sure you use kV if you want kVA - or use Volts and multiply by 1000. If you are doing per phase, the 1.732 is not needed.
Really, this is very basic for a EE. Refer to one of your first-year textbooks, or an EE Handbook.
David Castor
www.cvoes.com
RE: Power Consumption formula
120 A = 33.26 KVA
140 A = 38.8 KVA
143 A = 39.63 KVA
Total = 111.69 KVA
(120 A + 140 A + 143 A)/3 = 134.33 A ave.
134.33 x 480 x 1.73 = 111.68 KVA
Seems pretty close.
Bill
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Jimmy Carter
RE: Power Consumption formula