The next thing one needs to know is that the ratings of watts
and volt-amps are almost the same. When they say volt-amps,
they literally mean "volts x amps". Well, look at the WAV formula and you quickly see that it states "watts equal volts times amps". That means they're one and the same. Another rating commonly used is kVA, which simply means kilovolt-amps, or "thousands of volt-amps", just as kW means "thousands of watts". So if you have a UPS that can supply 10,000VA, that means it can supply 10kVA or 10kW. So all of the following are the exact same amount of power:
- 10,000W (watts)
- 10,000VA (volt-amps)
- 10kVA (kilovolt-amps)
- 10kW (kilowatts)
Now I've come across some information that leads me to believe that I'm not correctly understanding this information somehow. On eBay I've seen a UPStation unit rated at 10kVA and 7KW. I don't know how this is possible. If you've got the clue, send it my way. I think it's got something to do with the three-phase multiplier of 1.73, but I'm not positive.
Hmmm... this calculator has several ratios in it's calculations, why? I think I'm the clues may be in the next section. (Factoring the efficiency factor).
- A = (K * 1000)/E)
- A = (K * 1000)/(2*E)
- A = (K * 1000)/(1.73*E)
- W = K * 0.8
Another useful calculator.