EEE MCQ — Power Systems | ৫০টি প্রশ্ন ও উত্তর
Power Systems বাংলাদেশের বিদ্যুৎ খাতের চাকরিগুলোর (DESCO, BPDB, PGCB, REB) জন্য সবচেয়ে গুরুত্বপূর্ণ বিষয়। BCS-এর EEE subject paper-এও এখান থেকে উল্লেখযোগ্য প্রশ্ন আসে। নিচে ৫০টি নির্বাচিত MCQ দেওয়া হলো।
⚡ Transmission & Distribution
1. The standard frequency of AC power supply in Bangladesh is:
a) 50 Hz b) 60 Hz c) 25 Hz d) 100 Hz
✅ Answer: a
2. High voltage transmission is used to:
a) Increase current b) Reduce transmission losses (I²R losses)
c) Increase power factor d) Reduce insulation cost
✅ Answer: b
3. The national grid transmission voltage in Bangladesh is:
a) 11 kV b) 33 kV c) 132 kV / 230 kV / 400 kV d) 415 V
✅ Answer: c
4. The distribution voltage commonly used in Bangladesh for LT lines is:
a) 400V (3-phase) / 230V (single-phase) b) 11 kV
c) 33 kV d) 132 kV
✅ Answer: a
5. Corona loss in a transmission line is reduced by:
a) Increasing conductor diameter / using bundled conductors b) Reducing voltage
c) Using steel conductors d) Reducing line length
✅ Answer: a
6. The Ferranti effect occurs in a transmission line when:
a) The line is fully loaded b) The line is lightly loaded or on no-load
c) The power factor is unity d) The current is maximum
✅ Answer: b
7. The Ferranti effect causes:
a) Decrease in receiving end voltage b) Increase in receiving end voltage above sending end
c) Voltage to be equal at both ends d) No change in voltage
✅ Answer: b
8. ACSR conductor stands for:
a) Aluminium Conductor Steel Reinforced b) Aluminium Copper Steel Reinforced
c) Alternating Current Steel Resistant d) Advanced Conductor Shielded Reinforced
✅ Answer: a
9. The skin effect in a conductor is:
a) Concentration of current at the centre of the conductor
b) Concentration of AC current on the outer surface of the conductor
c) Uniform distribution of current d) Reduction of resistance at high frequency
✅ Answer: b
10. The surge impedance loading (SIL) of a transmission line is:
a) Load when line resonates b) Load at which line reactive power is balanced
c) Maximum load the line can carry d) Minimum load for stability
✅ Answer: b
🔌 Power Flow & Load
11. Load flow analysis is used to determine:
a) Fault currents b) Voltage profile and power flow in steady-state
c) Transient stability d) Motor starting characteristics
✅ Answer: b
12. Gauss-Seidel method in power systems is used for:
a) Fault analysis b) Load flow (power flow) solution
c) Transient stability analysis d) Economic dispatch
✅ Answer: b
13. The slack (swing) bus in a power flow study specifies:
a) Real and reactive power b) Voltage magnitude and angle (reference bus)
c) Real power and voltage magnitude d) Reactive power and voltage angle
✅ Answer: b
14. A PV bus (generator bus) specifies:
a) Real power and voltage magnitude b) Voltage magnitude and angle
c) Real and reactive power d) Reactive power and voltage magnitude
✅ Answer: a
15. The per-unit system in power systems is used to:
a) Increase accuracy of calculations b) Simplify calculations by normalizing quantities
c) Measure power in smaller units d) Convert AC to DC quantities
✅ Answer: b
⚠️ Faults & Protection
16. The most common type of fault in a power system is:
a) Three-phase fault b) Double line-to-ground fault
c) Single line-to-ground fault d) Line-to-line fault
✅ Answer: c
17. The most severe (highest current) 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 (symmetrical) fault
✅ Answer: d
18. Symmetrical components method was developed by:
a) Charles Steinmetz b) C.L. Fortescue c) Oliver Heaviside d) Nikola Tesla
✅ Answer: b
19. Positive, negative, and zero sequence components are used to analyze:
a) Balanced three-phase faults only b) Unbalanced faults in power systems
c) Load flow studies d) Economic dispatch
✅ Answer: b
20. An overcurrent relay operates when:
a) Voltage exceeds a set value b) Current exceeds a predetermined value
c) Power factor drops below 0.5 d) Frequency deviates from nominal
✅ Answer: b
21. A differential protection scheme is most commonly used for:
a) Transmission lines b) Transformers and generators
c) Capacitor banks d) Busbars only
✅ Answer: b
22. Distance (impedance) relay is used primarily for protection of:
a) Generators b) Transformers c) Transmission lines d) Motors
✅ Answer: c
23. A Buchholz relay is used to protect:
a) Generators b) Oil-immersed transformers c) Transmission lines d) Busbars
✅ Answer: b
24. The function of a circuit breaker is to:
a) Measure current b) Interrupt fault current and isolate faulty section
c) Regulate voltage d) Improve power factor
✅ Answer: b
25. SF6 (sulphur hexafluoride) is used in circuit breakers because:
a) It is cheap and abundant b) It has excellent arc-quenching and insulating properties
c) It is lighter than air d) It is non-toxic
✅ Answer: b
26. A fuse protects a circuit by:
a) Tripping a relay b) Melting and breaking the circuit during overcurrent
c) Absorbing excess voltage d) Reducing current automatically
✅ Answer: b
27. An earth fault relay (64) is used to detect:
a) Overcurrent b) Ground (earth) faults c) Overvoltage d) Under-frequency
✅ Answer: b
28. The impedance of a current transformer (CT) secondary should be:
a) Very high (open circuit) b) Very low (short circuit)
c) Equal to primary impedance d) 50 Ohms
✅ Answer: b (CT secondary should never be open-circuited)
🔋 Reactive Power & Power Factor
29. Power factor correction in a power system is done using:
a) Inductors b) Capacitor banks or synchronous condensers
c) Resistors d) Transformers
✅ Answer: b
30. A lagging power factor is caused by:
a) Capacitive loads b) Resistive loads
c) Inductive loads (motors, transformers) d) Lighting loads
✅ Answer: c
31. A leading power factor is caused by:
a) Inductive loads b) Capacitive loads c) Resistive loads d) Non-linear loads
✅ Answer: b
32. Reactive power compensation reduces:
a) Active power consumption b) Line current and I²R losses
c) System frequency d) Transformer rating
✅ Answer: b
33. STATCOM stands for:
a) Static Compensation Module b) Static Synchronous Compensator
c) Standard Current Compensation d) Static Current Module
✅ Answer: b
🌱 Renewable Energy & Modern Power Systems
34. HVDC transmission is preferred over HVAC for:
a) Short-distance transmission b) Very long-distance transmission and submarine cables
c) Low voltage distribution d) Industrial loads only
✅ Answer: b
35. The capacity factor of a solar PV plant is approximately:
a) 90–95% b) 70–80% c) 15–25% d) 50–60%
✅ Answer: c
36. A smart grid differs from a traditional grid mainly by:
a) Higher voltage levels b) Two-way communication and automated control
c) Using only renewable energy d) Operating without transformers
✅ Answer: b
37. The installed power generation capacity of Bangladesh (approx. 2024) is:
a) 5,000 MW b) 10,000 MW c) Over 25,000 MW (installed) d) 50,000 MW
✅ Answer: c
38. The Rural Electrification Board (REB) in Bangladesh supplies electricity through:
a) Direct connections from PGCB b) Palli Bidyut Samity (PBS) cooperatives
c) DESCO substations d) Private utilities
✅ Answer: b
🔁 Stability & Economics
39. Steady-state stability limit is the maximum power that can be transferred without:
a) Overheating b) Loss of synchronism under gradual load change
c) Voltage collapse d) Frequency deviation
✅ Answer: b
40. Transient stability refers to the ability of a power system to:
a) Remain stable under continuous load b) Remain in synchronism after a sudden large disturbance
c) Maintain frequency at 50 Hz always d) Prevent corona losses
✅ Answer: b
41. Equal area criterion is used to study:
a) Load flow b) Transient stability c) Economic dispatch d) Fault analysis
✅ Answer: b
42. Economic dispatch in power systems refers to:
a) Reducing transmission losses b) Optimal allocation of load among generators to minimize cost
c) Scheduling maintenance d) Maximizing reactive power
✅ Answer: b
43. The incremental cost criterion for economic dispatch states that all units should operate at:
a) Maximum capacity b) Equal incremental fuel costs c) Minimum capacity d) Equal output
✅ Answer: b
🔧 Switchgear & Substation
44. A busbar in a substation serves as:
a) A protection device b) A common junction point for connecting multiple circuits
c) A measurement device d) A power factor correcting device
✅ Answer: b
45. An isolator (disconnector) in a substation:
a) Can interrupt load current b) Is only operated when circuit is de-energized (no-load)
c) Protects against lightning d) Measures voltage
✅ Answer: b
46. A lightning arrester protects electrical equipment from:
a) Overcurrent b) Overvoltage due to lightning and switching surges
c) Under-frequency d) Reverse power
✅ Answer: b
47. The neutral grounding resistance in a power system is used to:
a) Increase fault current b) Limit ground fault current and reduce damage
c) Improve power factor d) Increase system voltage
✅ Answer: b
48. SCADA in a power system stands for:
a) System Control and Data Analysis b) Supervisory Control and Data Acquisition
c) Substation Control and Distribution Automation d) Signal Control and Data Application
✅ Answer: b
49. Energy Meter measures:
a) Instantaneous power b) Total electrical energy consumed (kWh)
c) Power factor d) Reactive power
✅ Answer: b
50. The voltage at a consumer's terminal in Bangladesh should be maintained within:
a) ±1% of nominal b) ±5% of nominal (230V ±5%)
c) ±20% of nominal d) Any voltage is acceptable
✅ Answer: b
গুরুত্বপূর্ণ তথ্য — বাংলাদেশের বিদ্যুৎ খাত
| বিষয় | তথ্য |
|---|---|
| ট্রান্সমিশন ভোল্টেজ | 132 kV, 230 kV, 400 kV |
| বিতরণ ভোল্টেজ | 33 kV, 11 kV, 400V/230V |
| ফ্রিকোয়েন্সি | 50 Hz |
| গ্রিড পরিচালনাকারী | PGCB (Power Grid Company of Bangladesh) |
| বিতরণ কোম্পানি | DESCO, DPDC, WZPDCL, NESCO, PBS (REB) |
পরবর্তী পোস্ট: Electronics & Semiconductor MCQ — ৫০টি প্রশ্ন ও উত্তর
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