1. The method of symmetrical components was introduced by:
(A) Nikola Tesla
(B) Charles Fortescue
(C) James Clerk Maxwell
(D) Lord Kelvin
2. Symmetrical components are used for analyzing:
(A) Balanced systems only
(B) Unbalanced three-phase systems
(C) DC circuits
(D) Single-phase loads
3. The three symmetrical components of an unbalanced system are:
(A) Real, reactive, and apparent components
(B) Positive, negative, and zero sequence components
(C) Active, passive, and neutral components
(D) Line, phase, and ground components
4. The positive sequence components represent:
(A) Normal balanced system operation
(B) Unbalanced system only
(C) Faulted condition
(D) Harmonic components
5. The negative sequence components represent:
(A) Balanced operation
(B) Unbalanced conditions with reverse rotation
(C) Zero voltage condition
(D) Ground faults
6. The zero sequence components represent:
(A) Equal in all three phases and in phase with each other
(B) Opposite in direction to positive sequence
(C) 120° apart in phase
(D) Voltage imbalance
7. The symmetrical components technique is mainly used in:
(A) Load flow studies
(B) Fault analysis and unbalanced systems
(C) Economic load dispatch
(D) Frequency control
8. The transformation from phase quantities to symmetrical components is:
(A) Linear
(B) Nonlinear
(C) Exponential
(D) Random
9. In a perfectly balanced three-phase system, which sequence component exists?
(A) Only positive sequence
(B) Only negative sequence
(C) Only zero sequence
(D) All three sequences
10. The negative sequence components cause:
(A) Heating in rotating machines
(B) Improved torque in generators
(C) Power factor correction
(D) Balanced operation
11. The zero-sequence current can flow only when:
(A) Neutral or ground path is available
(B) System is isolated
(C) Load is balanced
(D) Transformer is delta-connected
12. The zero-sequence current in a delta-connected system is:
(A) Zero
(B) Maximum
(C) Twice the line current
(D) Equal to the phase current
13. The direction of rotation of negative sequence phasors is:
(A) Same as positive sequence
(B) Opposite to positive sequence
(C) Random
(D) Stationary
14. In symmetrical component analysis, the operator ‘a’ is used to:
(A) Represent 120° phase shift
(B) Indicate polarity
(C) Denote frequency
(D) Represent impedance
15. The total set of phase quantities can be obtained by:
(A) Adding all symmetrical components
(B) Subtracting negative components
(C) Using only positive sequence components
(D) Ignoring zero sequence
16. Positive sequence impedance is:
(A) Same as normal system impedance
(B) Infinite
(C) Zero
(D) Negative
17. Negative sequence impedance is generally:
(A) Slightly higher than positive sequence impedance
(B) Slightly lower than positive sequence impedance
(C) Equal to positive sequence impedance
(D) Always zero
18. Zero-sequence impedance depends on:
(A) Grounding and transformer connections
(B) Load power factor
(C) Frequency
(D) System voltage
19. The positive sequence network is used to represent:
(A) Balanced operating conditions
(B) Short circuit impedance
(C) Transformer leakage only
(D) DC systems
20. The negative sequence network is similar to the positive sequence network except:
(A) The direction of current is reversed
(B) The impedance values are slightly different
(C) The voltage is zero
(D) The current is constant
21. The zero-sequence network differs from the others because:
(A) It includes the neutral or ground path
(B) It has no impedance
(C) It is always open
(D) It represents load current
22. In a line-to-line fault, which sequence components are present?
(A) Positive and negative
(B) Positive and zero
(C) Negative and zero
(D) All three
23. In a single line-to-ground fault, which sequence components are involved?
(A) Positive, negative, and zero
(B) Positive only
(C) Negative only
(D) Zero only
24. In a balanced three-phase fault, which sequence components are present?
(A) Only positive
(B) Positive and negative
(C) All three
(D) None
25. Zero-sequence voltage appears in a system when:
(A) Neutral is grounded
(B) System is balanced
(C) Load is purely resistive
(D) System frequency increases
26. The symmetrical component method simplifies:
(A) Unbalanced system analysis
(B) Frequency control
(C) Voltage regulation
(D) Economic load dispatch
27. The main application of sequence networks is in:
(A) Fault analysis
(B) Power factor correction
(C) Load forecasting
(D) Energy efficiency studies
28. Negative sequence current in a motor produces:
(A) Reverse torque and heating
(B) Forward torque and cooling
(C) Zero torque
(D) Reduced voltage
29. The zero-sequence network does not exist in:
(A) Isolated neutral systems
(B) Solidly grounded systems
(C) Resistance grounded systems
(D) Ungrounded delta systems
30. The symmetrical component method is preferred because:
(A) It converts unbalanced conditions into balanced networks
(B) It increases fault current
(C) It requires complex vector analysis
(D) It can only be used for balanced loads