Question 391Electricity & Electronics - QMED

70% to pass

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

Diagram for USCG Electrical QMED: What would be the source current and transformer current as shown in figure "B"...

ASource current is 12.5 amps, transformer current is 37.5 amps.

BSource current is 12.5 amps, transformer current is 62.5 amps.

CSource current is 37.5 amps, transformer current is 12.5 amps.

DSource current is 37.5 amps, transformer current is 92.5 amps.

AI Explanation

The correct answer is A) Source current is 12.5 amps, transformer current is 37.5 amps. This is correct because in a transformer with a unity power factor load, the source current will be the load current divided by the turns ratio of the transformer. With a 440 VAC supply and a 50 amp load, the source current is 50 amps divided by the turns ratio, which is 4:1. This results in a source current of 12.5 amps. The transformer current will be the load current, which is 50 amps, multiplied by the turns ratio, which is 4:1. This results in a transformer current of 37.5 amps. The other options are incorrect because they do not correctly apply the turns ratio to calculate the source and transformer currents.