1. The main purpose of short circuit analysis in power systems is to:
(A) Measure frequency variations
(B) Determine fault currents and equipment ratings
(C) Evaluate transformer efficiency
(D) Determine load flow
2. A short circuit in a power system results in:
(A) Increase in voltage
(B) Large current flow
(C) Power factor improvement
(D) Decrease in current
3. The most severe type of fault in a power system is:
(A) Single line-to-ground fault
(B) Line-to-line fault
(C) Double line-to-ground fault
(D) Three-phase fault
4. A symmetrical fault means:
(A) Equal fault currents in all three phases
(B) Fault in only one phase
(C) Unequal current magnitudes
(D) A fault in neutral
5. An unsymmetrical fault is a type of:
(A) Balanced fault
(B) Unbalanced fault
(C) Frequency disturbance
(D) Load fluctuation
6. The most common type of fault in power systems is:
(A) Three-phase fault
(B) Line-to-line fault
(C) Single line-to-ground fault
(D) Double line-to-ground fault
7. A short circuit mainly occurs due to:
(A) Insulation failure or accidental contact
(B) Overloading
(C) Open circuit
(D) Frequency variation
8. During a short circuit, the voltage at the fault point:
(A) Increases sharply
(B) Decreases sharply
(C) Remains constant
(D) Becomes zero for all buses
9. Short circuit current magnitude depends mainly on:
(A) Power factor
(B) System impedance up to the fault point
(C) Load demand
(D) Frequency
10. Short circuit studies are essential for:
(A) Power flow control
(B) Designing protective devices and equipment ratings
(C) Load forecasting
(D) Transmission efficiency calculation
11. The fault current is maximum when the fault occurs:
(A) Near the generator
(B) Near the load
(C) At transmission midpoint
(D) At a transformer secondary
12. The per-unit system is preferred in fault analysis because:
(A) It simplifies calculations and comparisons
(B) It increases accuracy of measurements
(C) It uses actual values
(D) It reduces system losses
13. The symmetrical component method is used for:
(A) Unbalanced fault analysis
(B) Balanced load flow
(C) Steady-state stability
(D) Frequency control
14. Positive sequence components represent:
(A) Normal balanced operation
(B) Faulted conditions
(C) Harmonics
(D) Zero voltage
15. Negative sequence components represent:
(A) Balanced operation
(B) Unbalanced conditions
(C) Zero sequence currents
(D) Transient stability
16. Zero sequence components exist only when:
(A) A return path through ground or neutral is available
(B) System is balanced
(C) All lines are open
(D) Load is purely inductive
17. In a single line-to-ground fault, the sequence networks are connected:
(A) In series
(B) In parallel
(C) Isolated
(D) Ignored
18. For a line-to-line fault, which sequence networks are used?
(A) Positive and negative sequence networks
(B) Positive and zero sequence networks
(C) Negative and zero sequence networks
(D) All three sequence networks
19. The initial high current immediately after a fault occurs is called:
(A) Subtransient current
(B) Transient current
(C) Steady-state current
(D) Fault-free current
20. The component of fault current that decays with time is the:
(A) DC component
(B) AC symmetrical component
(C) Steady-state current
(D) Load current
21. Subtransient reactance of a generator is used to estimate:
(A) The initial fault current
(B) Load current
(C) Average system losses
(D) Power factor
22. The transient period after a short circuit lasts for:
(A) A few cycles
(B) Several minutes
(C) Until system shutdown
(D) A few seconds only
23. The circuit breaker must be capable of:
(A) Carrying rated load current only
(B) Interrupting maximum fault current safely
(C) Reducing voltage harmonics
(D) Balancing reactive power
24. The current that a circuit breaker interrupts after the fault is known as:
(A) Breaking current
(B) Subtransient current
(C) Transient current
(D) Charging current
25. The breaking capacity of a circuit breaker is usually expressed in:
(A) Amperes
(B) MVA
(C) Kilowatts
(D) Volts
26. The system’s fault level at a bus helps determine:
(A) Equipment short circuit rating
(B) Load demand
(C) Power factor correction
(D) Transmission efficiency
27. The transient reactance of a synchronous machine is:
(A) Greater than subtransient reactance
(B) Less than subtransient reactance
(C) Equal to subtransient reactance
(D) Zero
28. During a fault, protective relays operate to:
(A) Restore frequency
(B) Isolate the faulty section
(C) Balance the system voltage
(D) Improve power factor
29. The main objective of short circuit studies is to:
(A) Determine relay settings and breaker ratings
(B) Reduce generation cost
(C) Analyze voltage regulation
(D) Improve load diversity
30. Short circuit analysis is essential during:
(A) System design and protection planning
(B) Routine maintenance only
(C) Power factor correction studies
(D) Load forecasting