Power System Operations and Control 4

Electrical Engineering MCQ Question Papers: Campus Placement

Subject: Power System Operations and Control 4

Part 4: List for questions and answers of Power System Operations and Control

Q1. Why are load flow studies carried out?

a) To study of stability of the system

b) For fault calculations

c) For planning the power system

d) All of these

Q2. What is the element of the graph that is not included in the tree called?

b) Branches

c) Oriented graph

d) All of these

Q3. What is an oriented graph?

a) A connection of network topology, represented by replacing all physical elements by lines

b) A graph in which the direction is assigned to each branch

c) A graph where at least one path exists between any two nodes of the graph

d) None of these

Q4. Why are series reactors used?

a) Improve the transmission efficiency

b) Improve the power factor of the power system

c) To bring down the fault level with in the capacity of the switchgear instrument

d) All of these

Q5. What are zero sequence components?

a) Three balanced phasors of equal magnitude and displaced by 120°

b) Three balanced phasors displaced by 120° and having phase sequence opposite to

that of the original phasors

c) Three phasors with equal magnitude and zero displacement

d) None of these

Q6. What does the positive sequence component consist of?

a) Three balanced phasors of equal magnitude and displaced by 120°

b) Three unbalanced phasors displaced by 120°

c) Three phasors with equal magnitude and zero displacement

d) None of these

Q7. What is the percentage of occurrence of symmetrical faults?

a) 10 %

b) 15 %

c) 5 %

d) None of these

Q8. What will be the multiplying factor if the speed of the circuit breaker is 2 cycles?

a) 2.2

b) 1.2

c) 2.8

d) 1.4

Q9. If the speed of the circuit breaker is 8 cycles or slower than that what will be the multiplying factor?

a) 2.3

b) 1.0

c) 1.5

d) 1.7

Q10. What is the rated breaking capacity of the circuit breaker?

a) The product of rated voltage and rated breaking current

b) The product of rated voltage and rated symmetrical breaking current

c) The product of fault voltage and breaking current

d) None of these

Q11. What is the multiplication factor to be multiplied with symmetrical momentary current to account for the presence of DC off set current?

a) 1.2

b) 1.5

c) 1.6

d) 2.5

Q12. Which among the following methods are generally used for the calculation of symmetrical faults?

a) Norton theorem

b) Thevnin’s theorem

c) Kirchhoff’s laws

d) Only (b) and (c)

Q13. Which among the following reactance have a greater value?

a) Sub transient reactance

b) Transient reactance

c) Synchronous reactance

d) All of these

Q14. On which among the following factors does the magnitude of the fault current depend?

a) Total impedance upto the fault

b) Voltage at the fault point

c) Both (a) and (b)

d) None of these

Q15. Which among these is the most severe fault?

a) Single line to ground fault

b) Double line to ground fault

c) Line to line fault

d) Symmetrical fault

Q16. In which portion of the transmission system is the occurrence of the fault more common?

a) Alternators

b) Transformers

c) Transmission lines

d) Underground cables

Q17. Which among these is the most commonly occurring fault?

a) Single line to ground fault

b) Double line to ground fault

c) Line to line fault

d) Fault due to all the three phases to earth

Q18. Which of the following fault results into a three phase faults?

a) Single line to ground fault

b) Double line to ground fault

c) Line to line fault

d) Fault due to all the three phases to earth

Q19. Which among the following assumptions are made in the reactance diagram?

a) The neutral reactance are neglected

c) The capacitance of the transmission lines are neglected

d) All of these

Q20. What is infinite bus in power system?

a) A large system with infinite voltage

b) A large system in which the voltage and frequency varies

c) A large system whose voltage and frequency remains constant throughout

d) Both (a) and (b)

Part 4: List for questions and answers of Power System Operations and Control