1. The main purpose of generator protection is to:
(A) Detect abnormal conditions and isolate the generator quickly
(B) Regulate voltage
(C) Increase efficiency
(D) Maintain load balance
2. The most important protection scheme for a generator is:
(A) Differential protection
(B) Overcurrent protection
(C) Distance protection
(D) Thermal protection
3. Generator differential protection operates when:
(A) The current entering and leaving the generator are unequal
(B) Load current increases
(C) Voltage fluctuates
(D) Power factor changes
4. The stator earth fault protection in a generator detects:
(A) Fault between winding and ground
(B) Overvoltage condition
(C) Phase imbalance
(D) Speed variation
5. Rotor earth fault protection is provided to:
(A) Detect insulation failure in rotor winding
(B) Protect stator from overload
(C) Maintain rotor speed
(D) Control excitation
6. Unbalanced loading in a generator is detected by:
(A) Negative sequence relay
(B) Differential relay
(C) Distance relay
(D) Overvoltage relay
7. Overcurrent protection alone is not sufficient for generator protection because:
(A) Generators have low short-circuit current capability
(B) It operates too fast
(C) It cannot detect rotor faults
(D) It requires pilot wires
8. Loss of excitation in a synchronous generator is detected by:
(A) Offset mho relay
(B) Thermal relay
(C) Overcurrent relay
(D) Voltage balance relay
9. Transformer protection is primarily based on:
(A) Differential and Buchholz relays
(B) Distance protection
(C) Overvoltage relays only
(D) Frequency relays
10. Buchholz relay is used in:
(A) Oil-immersed transformers
(B) Dry-type transformers
(C) Air-cooled transformers
(D) All of the above
11. The Buchholz relay operates on the principle of:
(A) Gas accumulation and oil movement during faults
(B) Voltage unbalance
(C) Temperature variation
(D) Frequency change
12. The Buchholz relay provides protection against:
(A) Internal faults in the transformer tank
(B) External short circuits
(C) Overloading
(D) Lightning surges
13. The most important protection for transformers above 5 MVA is:
(A) Differential protection
(B) Overcurrent protection
(C) Distance protection
(D) Frequency relay
14. The function of harmonic restraint in transformer protection is to:
(A) Prevent maloperation during magnetizing inrush
(B) Increase relay sensitivity
(C) Reduce system harmonics
(D) Detect earth faults
15. Transformer overcurrent protection is mainly used as:
(A) Backup protection
(B) Primary protection
(C) Neutral grounding protection
(D) Overvoltage control
16. The sudden pressure relay in transformer protection responds to:
(A) Rapid build-up of gas pressure due to severe internal fault
(B) Ambient temperature
(C) Oil leakage
(D) Magnetizing current
17. Differential protection of transformers may fail to operate correctly due to:
(A) CT saturation or mismatch
(B) Low fault current
(C) High resistance fault
(D) Open circuit in the secondary
18. Transmission line protection is mainly provided by:
(A) Distance and pilot protection schemes
(B) Differential protection only
(C) Overvoltage relay
(D) Thermal relay
19. Distance relays are preferred for transmission line protection because:
(A) Their operation depends on the impedance between the relay and the fault
(B) They require no current transformers
(C) They are slower than overcurrent relays
(D) They do not require voltage inputs
20. A pilot protection scheme uses:
(A) Communication channels between two ends of the line
(B) Separate grounding wires
(C) Harmonic restraint
(D) Voltage boosting transformers
21. The distance relay most suitable for long transmission lines is:
(A) Mho relay
(B) Impedance relay
(C) Reactance relay
(D) Overcurrent relay
22. Mho relays are inherently:
(A) Directional in nature
(B) Non-directional
(C) Voltage-dependent
(D) Frequency-based
23. Reactance relays are mainly used for:
(A) Short transmission lines
(B) Long transmission lines
(C) Busbar protection
(D) Transformer protection
24. Impedance relays are used primarily for:
(A) Medium-length transmission lines
(B) Overvoltage protection
(C) Frequency control
(D) Voltage regulation
25. The main disadvantage of overcurrent protection for transmission lines is:
(A) Difficulty in discriminating between near and far faults
(B) It operates too quickly
(C) It requires high impedance
(D) It ignores line resistance
26. For long EHV transmission lines, the preferred protection is:
(A) Distance protection
(B) Overcurrent protection
(C) Differential protection
(D) Earth leakage protection
27. The current transformers (CTs) used in protection circuits are required to:
(A) Accurately reproduce the fault current for relay operation
(B) Step up voltage
(C) Reduce frequency
(D) Increase impedance
28. The communication channel in pilot protection may be established through:
(A) Power line carrier, microwave, or fiber optic links
(B) DC supply line
(C) Neutral wire
(D) Local ground
29. Transformer differential protection must remain stable during:
(A) External faults
(B) Internal faults
(C) Ground faults
(D) High current unbalance
30. The combined protection of generators, transformers, and transmission lines ensures:
(A) Complete system selectivity and reliability
(B) Reduced system losses only
(C) Constant power factor
(D) Elimination of harmonics