In our building, we have a four wire 208v/120v Wye service.
I'm trying to measure the watts used by a subpanel, but the loads are unbalanced.
For example, for the 208v lines (black, red, blue) I get :
-- 42A
-- 84A
-- 80A
I know about P = √3 Vl × Il × cos φ where cos φ = power factor, but that's for balanced scenarios, right ?
I'm going to have to guess at the power factor - most of the loads are lighting & computers/monitors.
But anyone know how to calculate the total power draw ?
If you look on this page, Three Phase Current - Simple Calculation and look at the "Balanced Voltages" section it implies that for unbalanced systems you can still calc as such :
I'm trying to measure the watts used by a subpanel, but the loads are unbalanced.
For example, for the 208v lines (black, red, blue) I get :
-- 42A
-- 84A
-- 80A
I know about P = √3 Vl × Il × cos φ where cos φ = power factor, but that's for balanced scenarios, right ?
I'm going to have to guess at the power factor - most of the loads are lighting & computers/monitors.
But anyone know how to calculate the total power draw ?
If you look on this page, Three Phase Current - Simple Calculation and look at the "Balanced Voltages" section it implies that for unbalanced systems you can still calc as such :
- the line to neutral (phase) voltage VLN = 208/√3 = 120 V
- phase 1 apparent power = 42 x 120 = 5040 VA = 5.04 kVA
- phase 2 apparent power = 84 x 120 = 10080 VA = 10.08 kVA
- phase 3 apparent power = 80 x 120 = 9600 VA = 9.6 kVA
- Total three phase power = 5.04 + 10.08 + 9.6 = 24.72 kVA