A transformer with 360 turns in its primary coil and 18 turns in its secondary coil is designed to delivered an average power of 1400 W with a maximum voltage of 60 V. What is the maximum current in the primary coil?

Answer 1

The primary coil has 360/18 = 20 times the voltage of the secondary coil. It also has 1/20 the current.

The max current in the secondary circuit is sqrt2*rms current = 1.414*1400/60 = 33.0 A
In the primary coil, multiply that number by 20.