Quiz: Electrical Engineering 25 march 2020

 

Quiz: Electrical Engineering

Date: 25/03/2020

Exam: UPPSC AE

Topic: Miscellaneous

 

Each question carries 1 mark.

Negative marking: 1/3 mark

Time: 10 Minute

 

Q1. A 10 mH inductor carries a sinusoidal current of 1 A r.m.s. at a frequency of 50 Hz. The average power dissipated by the inductor is

(a) 0 W

(b) 0.25 W

(c) 0.5 W

(d) 1 W

L1Difficulty 3

QTags Network & Circuit Theory

QCreator Devbrat Kumar

 

Q2. The difference between the two half-power frequencies is called ……….

(a) resonant frequency

(b) quality factor

(c) mid-frequency

(d) bandwidth

L1Difficulty 3

QTags Network & Circuit Theory

QCreator Devbrat Kumar

 

Q3. 100% string efficiency means

(a) self-capacitance is zero

(b) shunt capacitance is maximum

(c) self-capacitance is maximum

(d) shunt capacitance is zero

L1Difficulty 3

QTags Power generation, transmission and distribution

QCreator Devbrat Kumar

 

Q4. If the fault current is 2000 A, the relay setting 50% and C.T. ratio 400/5, the plug setting multiplier will be

(a) 15

(b) 10

(c) 25

(d) 50

L1Difficulty 3

QTags Power generation, transmission and distribution

QCreator Devbrat Kumar

 

Q5. A wire having very high value of conductance is said to be

(a) very good conductor

(b) moderately good conductor

(c) insulator

(d) none of the above

L1Difficulty 3

QTags Basic electrical engineering

QCreator Devbrat Kumar

 

Q6. The armature conductors of a 6-pole, lap-would d.c. generator is divided into

(a) 2 parallel paths

(b) 4 parallel paths

(c) 3 parallel paths

(d) 6 parallel paths

L1Difficulty 3

QTags DC Generator

QCreator Devbrat Kumar

 

Q7. Wave-wound generators provide

(a) less current but more voltage

(b) more current but less voltage

(c) more current and more voltage

(d) none of the above

L1Difficulty 3

QTags DC Generator

QCreator Devbrat Kumar

 

Q8. Which of the following relation is correct, where β = current gain

(a) α=β/(1+β)
(b) β=α/(1-α)
(c) β=α/(1+α)
(d) both a and b

L1Difficulty 3

QTags Analog and digital electronics (electrical engineering)

QCreator Devbrat Kumar

 

Q9. If the excitation and terminal voltage of synchronous motor are kept constant and the load is increased then……….

(a) armature current decreases and power factor becomes power leading

(b) armature current increase and power factor becomes more leading

(c) armature current increases and power factor become more lagging

(d) None of these

L1Difficulty 3

QTags Synchronous motor

QCreator Devbrat Kumar

 

Q10. In a synchronous motor, the stator frame is made of………

(a) Stainless steel

(b) CRGOS

(c) Cast iron or welded steel plates

(d) Laminated silicon steel

L1Difficulty 3

QTags Synchronous motor

QCreator Devbrat Kumar

 

SOLUTIONS

 

S1. Ans.(a)

Sol. The average power dissipated by an inductor is zero.

S2. Ans.(d)

S3. Ans.(d)

Sol. If shunt capacitance is zero the charging current through each disc will be the same. This means that voltage across each disc is the same. This in turn means 100% string efficiency.

 

S4. Ans.(b)

Sol. Pick-up value = Rated secondary current of C.T. × Current setting

= 5 × 0.5 = 2.5 A

Fault current in relay coil = 2000 × 5/400 = 25 A

∴Plug setting multiplier = 25/2.5 = 10

 

S5. Ans.(a)

S6. Ans.(d)

Sol. In lap winding, No. of parallel paths = No. of poles

S7. Ans.(a)

Sol. Wave – wound has only two parallel paths.

 

S8. Ans. (b)

S9. Ans.(b)

Sol. in synchronous motor (when excitation kept constant) load is increases –

Pf will be more leading

Armature current increases

Torque angle increases

 

S10. Ans.(c)

Sol. in synchronous motor: –

Stator frame → made up of last iron/welded steel plates

Core → made up of silicon steel

 

 

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