Q1) The question is about a 440-V balanced 3-phase Y-connected circuit.
May I ask is the 440V phase voltage or line-to-line voltage and why?

Q2) I know the equation Iline = Vphase / (Zline + Zload)
Why is the voltage in phase but the current is line to line?

 

Q1 In a balanced 3-phase circuit the voltage is line to line. The centre of the Y (or star) is not connected. (sometimes it is connected to earth)

Q2 Don't forget that the currents in each of the 3 loads are 120deg phase difference. The current in each line is the phasor resultant of the current in two loads.

Hope this makes sense!

 

Hi JDT thanks for the help

Regarding A what happens if the structure is delta shape instead?

I dont understand b. Dont 120+120 degrees = 240 degrees?