single phase loads in 3 phase system angle consideration

[PE blues]

in a three phase system, phase A has phase to neutral load of 60 KW at 1pf, phase B has phase to neutral load of 72 KW at 1PF and Phase c to neutral load is 50 KW at 1 PF. To find single phase branch current

Ia=60/(480/1.732)

Ib=72/(480/1.732)=259.8 ang(-120)

Ic=50/(480/1.732)=180.4 ang(120)

Why is 120 phase displacement considered for Ib and Ic? The loads are not balanced so even if abc displacement is considered would it be 120 degrees?

 

[Flyer_PE]

The only reason the angles really matter is in calculating the neutral current. In this example, all of the loads are purely resistive (pf=1). If the loads had reactive components, the angles for the currents would change.

 

[PE blues]

Thanks Flyer_PE. When calculating neutral currents for ABC sequence, would we still consider B lagging A by 120 and C lagging A by 240? This is what is considered in the Chalapti book, but the Spin up exam 3 uses B leading A by 120 and C leading A by 240. Phase rotation sequence is not given in the problem so I assumed ABC and the solution doesn't look correct