Quiz: Electrical Engineering 19 Nov 2020

Quiz: Electrical Engineering
Exam: UPPSC-AE
Topic: Miscellaneous

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

Q1. Form factor can be expressed as the ratio of
(a)Average value to rms value
(b)Rms value to average value
(c)Peak value to average value
(d)Peak value to rms value

Q2. Peak factor can be expressed as the ratio of
(a)Average value to rms value
(b)rms value to average value
(c)maximum value to average value
(d)maximum value to rms value

Q3. The transformer used for AC welding sets is
(a)Booster type
(b)Step up type
(c)Step down type
(d)Equal turn ratio type

Q4. The commutator of a DC generator acts as:
(a)Amplifier
(b)Rectifier
(c)Load
(d)Multiplier

Q5. For RLC ac series circuits at resonance the current is:
(a)Minimum at leading p.f
(b)Minimum at lagging p.f
(c)Maximum at unity p.f
(d)Maximum at leading p.f

Q6. Skin effect existence can be observed in
(a) dc as well as ac transmission line
(b) dc transmission line only
(c) ac transmission line only
(d) cable carrying dc current

Q7. Grading of cables
(a) reduce insulation cost and increase current rating.
(b) reduce insulation cost but decrease current rating.
(c) Increases both
(d) None of above

Q8. A 50 Hz 220/400 V, 50 KVA single phase Transformer operates on 220 V, 40 Hz supply with secondary winding then,
(a) the eddy current loss and hysteresis loss of transformer decreases
(b) the eddy current loss and hysteresis loss of transformer increases
(c) the hysteresis loss of transformer increases while eddy current loss remains the same
(d) the hysteresis loss remains the same whereas eddy current loss decreases

Q9. When transformer winding suffers a short circuit, the adjoining turns of the same winding experience
(a) an attractive force
(b) a repulsive force
(c) no force
(d) none of the above

Q10. Reactance relay is best suited for the protection of
(a) phase fault
(b) Earth fault
(c) open-circuit faults
(d) None of the above

Solution

S1. Ans(b)
Sol. Form factor is the ratio of Rms value to average value

S2. Ans(d)
Sol. Peak factor is the ratio of maximum value to rms value

S3. Ans(c)
Sol. Step down type

S4. Ans(b)
Sol. Rectifier

S5. Ans(c)
Sol. Maximum at unity power factor

S6. Ans. (c)

Skin effect exists in ac transmission line only.

S7. Ans.(a)
Sol. Grading of cables reduce insulation cost and increase current rating.

S8. Ans. (c)
Sol. According to the relation given, W_h∝B_m^1.6 f
W_h∝(B_m^1.6 f)/f^0.6 ∝V^1.6/f^0.6 (as V∝B_m f)
W_e∝B_m^2 f^2
S9. Ans. (a)
Sol. Due to same direction of current in the adjoining winding it experiences force of attraction.

S10. Ans. (b)
Sol. Earth faults

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