Quiz: Electrical Engineering 05 Apr 2021

Quiz: Electrical Engineering
Exam: UPMRC SC/TO
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/3 mark
Time: 10 Minute

Q1. Which of the following speed control method of a DC machine is NOT a constant torque drive?
(a) Armature resistance control
(b) Armature voltage control
(c) Field flux control
(d) All of the above

Q2. In a transformer the voltage regulation will be zero when it operates at:
(a) Lagging pf
(b) Leading pf
(c) Unity pf
(d) Zero pf leading

Q3. Inductance of transmission line for a length of 400 km in unsymmetrical configuration are:
L_R=30 mH,L_Y=20 mH,L_B=25 mH
What will be the inductance of each transmission line after transposing?
(a) L_R=L_Y=L_B=75 mH
(b) L_R=L_Y=L_B=30 mH
(c) L_R=L_Y=L_B=25 mH
(d) L_R=L_Y=L_B=20 mH

Q4. In a Dynamometer type wattmeter if current coil and voltage coil connections are interchanged then
(a) Current coil will damage
(b) Voltage coil will damage
(c) No damage
(d) None of the above

Q5. For eliminating n^th harmonic from emf generated in the phase of 3-phase alternator, the chording angle should be:
(a) 1/n×full pitch
(b) n ×full pitch
(c) 2/n×full pitch
(d) 3/n×full pitch

Q6. The magnetic field due to an infinite linear current carrying conductor is
(a) H = μi/2πr A/m.
(b) H = i/2πr A/m.
(c) H = μi/(2r ) A/m
(d) H = i/r A/m

Q7. Which of the following is a ferromagnetic material?
(a) Tungsten
(b) Aluminium
(c) Copper
(d) Nickel

Q8. Area of hysteresis loop represents
(a) copper loss
(b) eddy current loss
(c) dielectric loss
(d) Energy loss to magnetize and demagnetize the core

Q9. A salient pole synchronous generator connected to an infinite bus power will deliver maximum power at a power angle of
(a) θ = 0
(b) θ = 90°
(c) θ = 45°
(d) θ = 30°

Q10. The connected load of a consumer is 2 KW and his maximum demand is 1.5 KW. The demand factor of the consumer is:
(a) 1.33
(b) 0.375
(c) 0.75
(d) None of the above

SOLUTIONS

S4. Ans.(a)
Sol. current coil has very small resistance. When it is connected in place of the voltage coil, then the whole current will flow through it and will cause damage to the current coil.

S5. Ans.(a)
Sol. For eliminating n^th harmonic: chording angle=1/n×full pitch

S6. Ans.(b)
Sol. Magnetic field, H=i/2πr A/m

S7. Ans.(d)
Sol. Nickel is a ferromagnetic material.

S8. Ans.(d)
Sol. Energy loss to magnetize and demagnetize the core.

S9. Ans.(b)
Sol. Active power of synchronous generator
P=EV/X_s Sin θ
∴ for Pmax, sin θ =1
⇒ θ =90°

S10. Ans.(c)
Sol. Demand factor=max. demand/connected load=1.5/2=0.75.

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