Using 3-phase vs 1-phase values

[bengaltiger14]

On a question like this, how would one know to use single phase vs three phase values? The solution converts KVAR to single phase. I'm assuming its because each 100 KVAR capacitor in the wye arrangement is assumed to be reactive power per phase and not the total reactive power?

 

[Zach Stone P.E.]

This is a three phase wye-connected capacitor.

If you want to find the capacitance (C) in each phase of the wye connection (so that you can change the frequency from 60 Hz to 50 Hz and see the resulting outcome), you'll need to use the voltage across each phase along with the reactive power supplied by each phase.

The power supplied by each phase, is the three-phase power divided by three.