Power Factor & Unbalance Distribution board

#1

Power Factor
I would like to get a Power Factor (PF) value for my devices (especially the big loads) to better understand whether the device is operating efficiently. As Sense would log this over time it could also be an indicator of preventative maintenance of the load.

*Extra points: break down the PF into displacement (fundamental) PF and harmonic PF.

Unbalance Load Factor
Having a balanced Distribution panel (draw approximately the same current on each leg) is important to the electrical company (affects their transformer I believe) and if you are on a demand power billing schedule that also gets affected.

This is a good read on the subject:

#2

My understanding is power factor has no impact on residential customers as they are billing on kwh not kvar. Anything you do to improve your power factor will save the utility money but will not impact your kwh usage. The same goes for an unbalanced panel, you can draw just about everything that is 120vac from one leg and it will not impact your billed kwh. Please correct me if I am mistaken on this.

#3

I second Howard’s view… The only thing balancing household loads will do, for you, is save a tiny bit wear and tear on your home’s wiring due to heating and electromigration. And in most cases you’ll have pretty good balance thanks to the way breaker boxes are designed, alternating legs for each new breaker added, and with 240V used for the largest loads. But you definitely won’t see any power savings as the Spruce article implies, though it may be a little better for the power company.

Also, I’m not sure that monitoring a device’s power factor is all that useful for looking at efficiency. The power factor of most motors will mostly change/drop to reflect transient loading conditions either at startup or when a new load is added during steady state. Plus start and run capacitors alter the power factor so much that you aren’t really seeing the underlying motor power factor anyhow. The power factor measurement might tell you whether you have a blown start or run capacitor, but if you have a blown start capacitor in your AC unit, you’ll know it !

#4

On the other hand, if using a generator with a transfer switch, it might help by load balancing the power to minimize over taxing your generator.

#5
#6

I believe you are confusing major electrical distribution systems, industrial users, and utility companies where these things are an issue. For a typical homeowner or even light commercial user that is not billed for KVAR or demand none of this has any consequence.

Years ago as a plant engineer I was tasked with looking at power factor adjustment for a PVC plant. The power factor was only about 82% if memory serves me right. I came up with the equipment to bring it up to 90% which would prevent utility penalties. The plant accountant explained to me that because we had common billing with a much larger plant owned by the same company even if we raised it to 100% it would have no impact on the total bill. Just goes to show that theory and practice don’t always match.

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