# Power Systems Questions and Answers – Comparison of Angle and Voltage Stability – 1

This set of Power Systems Multiple Choice Questions & Answers (MCQs) focuses on “Comparison of Angle and Voltage Stability – 1”.

1. For the figure depicting the two generators connected via the transmission line having and impedance ‘jX’ ohms. Machine A at voltage Va at angle δ will supply active power to machine B at voltage Vb and angle zero, when δ is _____________ a) positive
b) negative
c) zero
d) any of the mentioned

Explanation: The real power transfer takes place when the power angle is greater than the other station.

2. For the figure depicting the two generators connected via the transmission line having and impedance ‘jX’ ohms. Machine A at voltage Va at angle δ will supply active power to machine B at voltage Vb and angle zero, when δ is _____________ a) Va>Vb
b) Va<Vb
c) Va = Vb
d) Any of the mentioned.

Explanation: The reactive power that will flow through the system when the voltage of the bus is more than the other one.

3. A three phase alternator can supply a maximum of 5000 KVA at 66 kV. The machine has internal resistance of 6%. The reactance per phase of the limiting reactor if the steady apparent power on the short circuit do not exceed 5 times full load is ____________
a) 1.22 Ω
b) 2.44 Ω
c) 5 Ω
d) 1.84 Ω

4. A transmission line has Z= (2+j8)Ω has 10% of the voltage regulation with the lagging load of 0.8. If the load is 0.707 leading, the V.R. is ________(Assume the current is same in both cases)
a) -6.63%
b) -5.77%
c) -10%
d) -8.63%

5. A generating station has a connected load of 43 MW. The unit generated having 61.5*106 per year. The load factor will be _____________
a) 0.35
b) 0.33
c) 0.5
d) 0.45

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6. The symmetrical components are used in fault analysis because of _______________
a) sequence of network do not have mutual coupling
b) number of equations is smaller
c) results are required in symmetrical components
d) none of the mentioned

Explanation: Due the non-coupling of the transmission system sequence network it is easy to implement symmetrical fault analysis.

7. Two conductors of a single phase line, having the 1cm diameter and arranged in a vertical plane with one conductor mounted 1m above other. A second identical line is mounted at same height as first and spaced horizontally 0.25m apart. The two upper and lower conductors are connected in parallel. The loop inductance of the line is ______(mH/km)
a) 0.84
b) 0.42
c) 0.32
d) 0.64

8. Two conductors of a single phase line, having the 1cm diameter and arranged in a vertical plane with one conductor mounted 1m above other. A second identical line is mounted at same height as first and spaced horizontally 0.25m apart. The two upper and lower conductors are connected in parallel. The inductance of the line is __________(mH/km)
a) 0.42
b) 0.84
c) 0.55
d) 0.80

9. A transmission line has line parameters A =0.8, B= 200ʟ90o, C = 0.5*10-6 operating at 400kV at no load. The sending current in line will be ___________
a) 0.1443
b) 1.443
c) 0.324
d) 3.245

10. A 2-wire ring distributor is 300m long and fed at 240V at ‘A’. At ‘B’, 150m away from A, a load of 120A is taken and at ‘C’, 100m away in opposite direction a load of 80A is taken. If the resistance per 100m of single conductor is 0.03Ω, then current in section AB feeder is ___________
a) 86.67 A
b) 48.76 A
c) 88 A
d) 98.4 A

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