Power Electronics Help

Thread Starter


Joined May 1, 2007
Hi, i have a assignment due in few days and i have no clue on how to start on this problem.. any help would be greatly appreciated. here is the question.

A three phase 4 wire supply has all the
following loads connected
1: phase a-n 11.5kVAr capacitor
2: phase b-n 10.8kVA 0.72 lagging power factor load, and
3: phase c-n 17.3kW electric heating load
4: three phase delta connected balanced load of 14.66kVA, 45 degree lagging
All load values are described on the basis of a perfect 415/240V supply.
(i) Obtain the 4 relevant admittances

Calculate the individual line currents and phase to neutral and line to line voltages for the
cases of
a(ii) a healthy 3 phase supply (partial ans. Ic = 87.7 A∠111) and
a(iii) with the neutral broken. (partial ans. Ic = 14.9∠59.9 )
In a(iii) calculate the line to earth voltages as well as the phase to neutral (star) point voltages.