Question

Table 1

Load	Rating	Power Factor
Lighting	41.1kW	0.7 Lagging
Lights	12.2 kVa	0.67 Lagging
Ventilation fans	9 kVa	0.7 lagging
Heat pump	18 kW	0.707 Lagging
misc equipment	11.3 kVa	0.55 lagging
peak charging demand	209 kW	unity

Calculate the following for the car park using the data from Table 1:

a) the maximum real power demand P (kW)

b) maximum reactive power demand Q (kVAr)

c) the total apparent power demand S (kVA)

d) also, calculate the maximum current magnitude |I| if the supply voltage magnitude |V| is 3.3 kV and the supply frequency is 50 Hz.

e) Calculate the overall car park power factor.

f) Calculate the rating of the capacitor bank (μF) needed to improve the car park power factor to unity.

g) Calculate the new maximum current magnitude, after power factor correction. Again assume the supply voltage magnitude is 3.3kV and frequency is 50 Hz.

h) Select the cable ID from Table 2 that you would use to supply the car park BEFORE AND AFTER power factor correction has been applied.

i) Comment on your result.

Table 2

Cable ID	Rating (A)	Cable ID	Rating (A)
A	20	J	100
B	25	K	110
C	30	L	120
D	40	M	130
E	50	N	140
F	60	O	150
G	70	P	160
H	80	Q	170
I	90	R	180

Answer 1