Power Systems Questions and Answers – Flux Linkages of an Isolated Current-Carrying Conductor

This set of Power Systems Multiple Choice Questions & Answers (MCQs) focuses on “Flux Linkages of an Isolated Current-Carrying Conductor”.

1. A 500 MW, 21 kV, 50 Hz three phase two pole alternator has 0.8 lagging p.f. with moment of inertia of 27.5×10³ kgm^-2. The inertia constant H will be _______ MJ/MVA.
a) 2.17
b) 4.2
c) 2.82
d) 2.62
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Answer: a
Explanation:

2. If the power system network is at Vs∠δ and receiving end voltage is Vr∠0 consisting of the impedance of TL as (R+j5)Ω. For maximum power transfer to the load, the most appropriate value of resistance R should be __________
a) 1.732
b) 3
c) 1.2
d) 0.33
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3. At a 33kV 50 Hz to a bus a load of 35 MW is connected. To improve the power factor to unity a synchronous phase modifier is connected taking 5 MW. If the SPM is represented as delta connected impedance, where in each phase we have capacitor connected parallel to resistance forming RC parallel network, then the value of this resistance is ___________
a) 653.4 Ω
b) 753.6 Ω
c) 280.4 Ω
d) 682 Ω
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4. At a 33kV 50 Hz to a bus a load of 35 MW is connected. To improve the power factor to unity a synchronous phase modifier is connected taking 5 MW. If the SPM is represented as delta connected impedance, where in each phase we have capacitor connected parallel to resistance forming RC parallel network, then the value of this capacitance is __________
a) 25.57 μF
b) 76.2 μF
c) 32.2 μF
d) 24 μF
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5. The transmission efficiency for a single phase line can be expressed as ____________
a) \(\frac{VrI \cos \theta}{Vr \cos \theta r + 2RI^2}\)
b) \(\frac{VrI \cos \theta}{Vr \cos \theta r + RI^2}\)
c) \(\frac{VrI \cos \theta}{Vr \cos \theta r + 3RI^2}\)
d) \(\frac{\sqrt{3} VrI \cos \theta}{\sqrt{3} Vr \cos \theta r + 2RI^2}\)
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6. The transmission efficiency for a three phase line can be expressed as _________
a) \(\frac{\sqrt{3} VrI \cos \theta}{\sqrt{3} Vr \cos \theta r + 2RI^2}\)
b) \(\frac{\sqrt{3} VrI \cos \theta}{\sqrt{3} Vr \cos \theta r + 3RI^2}\)
c) \(\frac{3 VrI \cos \theta}{3 Vr \cos \theta r + 2RI^2}\)
d) \(\frac{3 VrI \cos \theta}{3 Vr \cos \theta r + 3RI^2}\)
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7. If the flux linkages are varied sinusoid with current, then what can be concluded about the inductance?
a) Constant
b) Varying with the current
c) Linearly varying
d) Exponential change
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8. The principle behind the influence of the power lines on the telephone lines is __________
a) Faraday’s laws
b) Mutual inductance
c) Self inductance
d) All of the mentioned
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9. The magnetic flux intensity due to the current flowing inside the conductor is _________

a) \(\frac{yI}{2 \pi r^2}\)
b) \(\frac{yI}{\pi r^2}\)
c) \(\frac{rI}{2 \pi y^2}\)
d) \(\frac{rI}{2 \pi y^2}\)
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Answer: a
Explanation: Referring the ampere’s Law,
2πyH=Iy
Assuming uniform current density,

10. The flux density B, y meters from the centre of conductors in the following diagram, is _______
a) \(\frac{\mu y I}{2 \pi r^2}\)
b) \(\frac{y I}{2 \pi r^2 \mu}\)
c) \(\frac{5 \mu y I}{2 \pi r^2}\)
d) \(\frac{\mu r I}{2 \pi y^2}\)
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Answer: a
Explanation: Referring the ampere’s Law,
2πyH=Iy
Assuming uniform current density,

11.The internal flux linking the single infinite conductor causes the inductance of ___________
a) 0.5 *10^-7 H/m
b) 2 *10^-7 H/m
c) 0.5 *10^-7 ln(r) H/m
d) 2 *10^-6 H/m
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12. The inductance of the conductor contributed by the flux between the point D outside at the distance d from conductor is _____________
a) 0.461 log(d/r) mH/km
b) 0.4 log(d/r) mH/km
c) 0.461 log(r/d) mH/km
d) 0.461 log(d/r) H/km
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Sanfoundry Global Education & Learning Series – Power Systems.

To practice all areas of Power Systems, here is complete set of 1000+ Multiple Choice Questions and Answers.