impedances of:

Za = 40 ohm; Zb = j 40 ohm; Zc = 20 j 20 ohm.

Calculate the phase and line currents.

2) A star-connected 400 V resistive load is connected to a 3-wire system. The

load has impedances of:

Za = 20 ohm; Zb = 40 ohm; Zc = 40 ohm.

Calculate the voltage of the neutral point.

3) An unbalanced star-connected load on a 220 V 60Hz 4-wire system. The legs of the load have impedances of:

Za = 5 ohm; Zb = 5 +j 5 ohm; Zc = 5 j 5ohm.

To insure correct phase voltage the star is connected to the neutral line

Calculate the phase and neutral currents.

4) An 400 V (line-line) star-connected unbalanced load has an earthed start point.

The load on phase 1 is 10 ohm, the load on phase 2 is 10 + j5 ohm and the load on

phase 3 is 10 j5 ohm. Calculate the phase currents and the star to earth current

and sketch the current phasor diagram.

I can do the balance system but the unbalanced I can't. and I would like to ask what is the diffrenece between xxx V (line-line) and xxxV xxHz and the difference between the 4-wire system and 3-wire system.

thank you.