What would be the source current and transformer current as shown in figure "B" of the illustration, with the secondary tap connected as shown, if the supply voltage at the branch circuit breaker is 440 VAC and the unity power factor load current draw is 50 amps? Illustration EL-0083

Correct Answer: Option D — source current is 12.5 amps, transformer current is 37.5 amps.

In auto-transformers and buck-boost configurations under IEEE 45 guidelines, currents divide between series and common windings based on turns ratio. With 440 VAC supply and 50A load, vector current division yields a source current of 12.5 amps and transformer current of 37.5 amps.