What is the importance on transformer utilization factor?

Answer 1

Ulitization factor is how much of the designed total is used. My house is fed off a 50KVA transformer. It's capable of supplying 50KVA continuously, but it's probably only gets used at its' full potential every once in awhile (when my neighbors and I wake up in the morning, and when we get home from work and eat dinner, perhaps). Say it only gets used at 30KVA on average. The utilization factor would be 30/50, or 60%.

Answer 2

with a very good transformer you may get 95% efficiency

this is mostly due to eddy current losses in the core or magnetization losses

so with 100va transformer you lose 5 va

if you need 10va to charge your cell fone battery

with the 100va transformer 10va goes to the phone and 5 to keep the transformer warm

you wish to make a call while the phone is charging you need 5 plus the 10 to charge the battery a 20va transformer you only lose 1 to heat the wall wart

if you are out most of the day and want to charge it in 1/2 hour you need the 100va seems like extraordinary expense on the chance you forget to put it on the charger before you go to bed