Quiz: Electrical Engineering 20 May 2020

Quiz: Electrical Engineering

Exam: UPSSSC JE

Topic: Switchgear and protection

 

Each question carries 1 mark.

Negative marking: 1/4 mark

Time: 10 Minute

 

Q1. The most serious consequence of a major uncleared short-circuit fault could be

(a) Blowing of fuse

(b) fire

(c) heavy voltage drop

(d) none of these

 

 

Q2. Which of the following result in a symmetrical fault?

(a) single phase to earth

(b) phase to phase

(c) All the three phases to earth

(d) two phase to earth

 

 

Q3. Which portion of transmission system is more prone to faults?

(a) Alternator

(b) transformer

(c) Overhead lines

(d) Underground cable

 

 

Q4. Which portion of power system is least prone to fault?

(a) Switchgear

(b) Alternator

(c) Overhead lines

(d) Transformer

 

 

Q5. The most common type of fault is

(a) Single phase to ground

(b)Two phase to ground

(c) Phase to phase

(d) three phase to ground

 

Q6. The per unit value of a 4 Ω resistance at 100 MVA base and 10 kV base voltage is

(a) 6 pu

(b)8 pu

(c)4 pu

(d)10 pu

 

 

Q7. Series reactor are used to

(a) improve the transmission efficiency

(b) improve the power factor of the power system

(c) improve the voltage regulation

(d) Bring down the fault level within the capacity of the switch gear

 

 

Q8. Current limiting reactors may be

(a) air cored air cooled

(b) oil immersed magnetically shielded

(c) oil immersed non magnetically shielded

(d) any of above

 

 

Q9. Symmetrical components are used in power system for the analysis of

(a) balanced 3 phased faults

(b) unbalanced 3 phase faults

(c) normal power system under steady condition

(d) Stability of system under disturbance

 

 

Q10. The positive sequence current of a transmission line is:

(a) always zero

(b) 1/3 of negative sequence current

(c) equal to negative sequence current

(d) 3 times negative sequence current

 

 

Solutions

 

 

 

S1. Ans.(b)

Sol. Fire is the most serious consequence.

 

S2. Ans.(c)

Sol. All the three phases to earth.

S3. Ans.(c)

Sol. Overhead lines

S4. Ans.(b)

Sol. Alternator

S5. Ans. (a)

Sol. The most common type of fault is Single phase to ground.

 

S6. Ans. (c)

Sol.  Rpu = R(ohm) ×MVA/(kV)^2
= 4 ×100/10^2 = 4 pu

S7. Ans. (d)

Sol. Bring down the fault level within the capacity of the switch gear.

S8. Ans. (d)

Sol. Any of above

S9. Ans.(b)

Sol. unbalanced 3 phase faults

S10. Ans. (b)

Sol. 1/3 of negative sequence current

 

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