KVA/KW Calculations

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I was simply trying to make the point that a single total power factor figure for a three phase 4-wire circuit with different loads in each phase it pretty meaningless.

I didn't think it was bickering - but I'm not a mod and also different nuances in the use of the English language may have made it seem that way to others bearing that we had at least three different nationalities in this thread.

I note also that my last response to tkb seems to have gone.
This was a prurely technical matter relating to his spreadsheet.
 
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tkb said:
This is the capacitor bank that is currently installed.

It is an ABB C485G22.5-3FI capacitor bank connected to the service.
I didn't install it, but I think a capacitor may have failed in it.
I was trying to determine if it is sized correctly or needs to be upsized.
I am sure it's not the correct style unit for the service.

I had the following readings,

Phase A, 19.5a
Phase B, 12.5a
Phase C, 19.5a

A to B, 66.4?F
A to C, 100?F
B to C, 65.8?F
Click to expand...
I think it's seriously shot.
At 22.5kVAr, the line current should be 27A.
Assuming the capacitors are connected in delta they each ought to be about 86uF.
If you measuse A to B at the terminals you will have that element plus the A to C and C to B both in series but the combination in parallel with A to C.
That would give a reading of about 130uF between any two terminals.
The capacitors are self healing. My understanding of this is that if the insulation between layers gets punctured, then the foil recedes from that thus reducing the effective area and consequently capacitance value.

Whatever, the unbalanced readings indicate that the unit clearly isn't healthy.
Replacement would seem to be the way to go. But maybe with a higher voltage unit.

P.S. I note that your spreadsheet now has the correct kW.
 
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