given that volts x amps watts why dont they just rate a transformer by kilowatts. I havent been able to link the logic behind rating a transformer by KVA, but there must be a reason. If you think you can help me I am eager to learn and will appreciate your help.
With alternating current (AC) it is possible for the current and voltage to be out of phase. When they are exactly in phase KVA and KW are the same. If they are completely out of phase, the KW will always be zero regardless of how high the KVA is. Homes are usually billed only for KW. Commercials users are billed for a combination of KW and KVA.
well from what my teacher told us kilowatts is reserved for real average power. As you know inductors and capacitors have no average power which means that the power in those elements are just being recycled over and over again. for sinusoidal steady state this power is imaginary (mathematically) and is giving the kVA. It's just terminology.
Mick Johnson and Mike Roberts asked the same question. You should see their answers side by side.
