I did a search on the forum but found no answer. The question is how to convert kWH from a utility bill to kVA to find demand on a building for that billing period.
What I have is kWH / hours (number of days on electric bill x 24) then X power factor = kVA. is this correct?
thanks.
No, not correct, unless the load is completely constant over the month (load factor of 100%). I've seen load factors over 90%, but that's rare. Also, be careful using the terms "kva" and "demand" interchangeably. Demand can be measured in kva but it's much more likely to be measured and expressed in kw.
Converting from kw to kva is easy. As the previous poster noted, kw divided by (not times) PF equals kva. So, if the demand is 100 kw and the power factor is 0.8, then kva is 125. But your utility bill may not have the power factor indicated. For residential or small commercial, it's almost never measured. For industrial and the like it almost surely is. Even then, it's not always explicitly listed on the bill.
But to return to the load (not power) factor concept, consider a theoretical customer with a constant 1 kw load. His monthly bill from the POCO would show 720 kwh of energy consumed (30 days x 24 hours/day x one kw). Since you know his load to be a constant 1 kw, that's his demand, his max. And if you knew the power factor you could convert kw to kva. A different customer who used 720 kwh in a month could have a demand of just about anything. If the load was some large machine that only ran for an hour each month, his demand would be 720 kw. Admittedly this is quite a stretch. But I'm trying to illustrate a point.
When I worked for the POCO, we were often asked how to "convert" kwh to kw demand. You can't. You can make a reasonable guess in many cases, but there is no direct conversion. Having said all that, the new smart meters often capture demand info, even at the residential level. Whether or not your utility has such meters installed, and whether or not they enable the customer to access the data, is another story.
