QUESTION 1

A 208V three phase power system is shown in Figure 1 above. It consists of an ideal 208V three-phase generator connected through a three-phase transmission line to a load. The transmission line has an impedance of 0.06+j0.12Ω per phase, and the load has an impedance of 12+j9Ω per phase. For this simple balanced power system, find

a) The magnitude of the line current ( ). (2 marks)

b) The magnitude of the load’s line-to-line voltage ( ) and phase voltage (). (4 marks)

c) The real, reactive and apparent powers consumed by the load. (6 marks)

d) The real, reactive and apparent powers supplied by the generator. (6 marks)

e) Power factor for both the load and the generator. (2 marks)

[2+4+6+6+2=20 marks]End of Question 1

Page 1

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Figure 1

0.06Ω

0.06Ω

0.06Ω

j0.12Ω

j0.12Ω

j0.12Ω

= 12+j9208V

_

+

QUESTION 2

A 208V three phase power system is shown in Figure 2 above. It consists of an ideal 208V three-phase generator connected through a three-phase transmission line to a load. The transmission line has an impedance of 0.06+j0.12Ω per phase, and the load has an impedance of 12+j9Ω per phase. For this simple balanced power system, find

f) The magnitude of the line current ( ). (2 marks)

g) The magnitude of the load’s line-to-line voltage ( ) and phase voltage (). (4 marks)

h) The real, reactive and apparent powers consumed by the load. (6 marks)

i) The real, reactive and apparent powers supplied by the generator. (6 marks)

j) Power factor for both the load and the generator. (2 marks)

[2+4+6+6+2=20 marks]End of Question 2

Page 2

+ _

+ _

+ _

Figure 2

0.06Ω

0.06Ω

0.06Ω

j0.12Ω

j0.12Ω

j0.12Ω

= 12+j9

208V

_

+