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EE 301: Power System Engineering

Tutorial-1

1. A capacitor needs to be connected across a 100 kV, 50 Hz, AC source to generate 75MVAr. What should be the value of the capacitance?

(Ans: 23.87 F)

2. A single phase AC voltage of 240 V is applied to a series circuit whose impedance is10 060 . FindR, X, P, Q and power factor of the circuit.

(Ans:R=5.0, X=8.66, P=2880W, Q=4988 varand power factor=0.5 lagging)

3. If a capacitor is connected in parallel with the circuit of the previous problem and ifthis capacitor supplies 1250 VArs. Find P and Q supplied by 240V source and

resultant power factor. (Ans:P=2880 and Q=3738 and resultant power factor=0.61 lagging)

4. In a balanced three phase system the Y connected impedance are 10 030 . IfVbc=416

090 V, specifyIcn in polar form.(Ans:Icn=24

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8. A three-phase line has impedance of 0.4 +j2.7 per phase. The line feeds two balancedthree phase loads that are connected in parallel. The first load is absorbing 560.1 kVA

at 0.707 power factor lagging. The second load absorbs 132 kW at unity power factor.

The line-to-line voltage at the load end of the line is 3810.5 V. Determine:

(a) The magnitude of the line voltage at the source end of the line.

(b) Total real and reactive power losses in the line.

(c) Real and reactive power supplied at the sending end of the line.(Ans: (a) 4160 V (b) 12 kW+j81 kvar (c) 540kW+j477 kvar)