PYQ-STYLE MCQs – POWER SYSTEM DISTRIBUTION

 

100 CUSTOM PYQ-STYLE MCQs – POWER SYSTEM DISTRIBUTION

Q1. The main reason for using high voltage in distribution is:
A) To reduce copper loss
B) To increase frequency
C) To improve PF
D) To reduce corona
Ans: A

Q2. A radial distributor fed from one end has maximum voltage drop:
A) At the sending end
B) At the middle
C) At the receiving end
D) Same everywhere
Ans: C

Q3. The diversity factor of a distribution system is always:
A) Less than 1
B) Equal to 1
C) Greater than 1
D) Zero
Ans: C

Q4. In a 3-phase, 4-wire system, the neutral carries:
A) No current always
B) Sum of line currents
C) Only unbalanced current
D) Zero-sequence current only
Ans: C

Q5. Which system gives highest reliability?
A) Radial
B) Ring main
C) Interconnected
D) DC 2-wire
Ans: C

Q6. The annual load factor of a domestic consumer is generally:
A) 0.1 – 0.3
B) 0.5 – 0.6
C) 0.7 – 0.8
D) >0.9
Ans: A

Q7. The primary distribution voltage in Indian urban areas is commonly:
A) 400 V
B) 3.3 kV
C) 11 kV
D) 66 kV
Ans: C

Q8. A load curve helps to determine:
A) Maximum demand
B) Load factor
C) Plant capacity factor
D) All of the above
Ans: D

Q9. Feeder design is mainly based on:
A) Current carrying capacity
B) Voltage drop
C) Power factor
D) Loss minimization
Ans: A

Q10. Distribution transformers usually operate with:
A) Constant load
B) Overload
C) Variable load
D) No load
Ans: C

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Q11. For minimum copper loss, distributors should be operated at:
A) Unity PF
B) Lagging PF
C) Leading PF
D) Zero PF
Ans: A

Q12. A customer’s maximum demand is 100 kW, annual consumption is 400 MWh. The load factor is:
A) 0.25
B) 0.45
C) 0.65
D) 0.80
Ans: B

Q13. The voltage regulation of a radial distributor is worst:
A) At balanced load
B) At power factor unity
C) At lagging PF
D) At leading PF
Ans: C

Q14. A ring distributor reduces:
A) Line losses
B) Voltage drop
C) Reliability issues
D) All of the above
Ans: D

Q15. The economy of distribution increases with:
A) Low diversity factor
B) High load factor
C) Low utilization factor
D) None
Ans: B

Q16. The unit for energy consumption is:
A) kVA
B) kVAh
C) kW
D) kWh
Ans: D

Q17. Which is true for a DC distributor?
A) No charging current
B) High corona loss
C) Less efficient
D) More insulation cost
Ans: A

Q18. Maximum demand of 500 consumers is 2 kW each. If the maximum demand on the station is 600 kW, the diversity factor is:
A) 1.0
B) 1.2
C) 1.5
D) 1.67
Ans: D

Q19. Which distribution system is simplest and cheapest?
A) Ring main
B) Radial
C) Interconnected
D) Mesh
Ans: B

Q20. Voltage regulation is best in:
A) Radial system
B) Ring main system
C) Interconnected system
D) Both B & C
Ans: D

Q21. Distribution transformer efficiency is maximum at:
A) Full load
B) ¾ load
C) Load where copper loss = iron loss
D) No load
Ans: C

Q22. The voltage unbalance in a 3-phase system should not exceed:
A) 1%
B) 2%
C) 5%
D) 10%
Ans: B

Q23. ABCD constants are mainly used for:
A) Transmission line analysis
B) Distribution feeders
C) Generator modeling
D) Load forecasting
Ans: A

Q24. The power factor of a distribution system can be improved by:
A) Shunt capacitors
B) Series inductors
C) Increasing load
D) Higher resistance conductors
Ans: A

Q25. For urban distribution, the most common system is:
A) Overhead radial
B) Underground ring main
C) Overhead mesh
D) DC 3-wire
Ans: B

Q26. The load curve plotted on a yearly basis is called:
A) Chronological curve
B) Load duration curve
C) Annual load curve
D) Demand curve
Ans: C

Q27. The “demand factor” is always:
A) Greater than 1
B) Less than 1
C) Equal to 1
D) Zero
Ans: B

Q28. A feeder in a distribution system:
A) Connects substation to distributor
B) Connects load to transformer
C) Supplies consumers directly
D) None
Ans: A

Q29. The connected load is always:
A) Less than maximum demand
B) Greater than maximum demand
C) Equal to maximum demand
D) None
Ans: B

Q30. The utilization factor is defined as:
A) kWh generated / maximum demand × hours
B) Maximum demand / connected load
C) Average load / maximum demand
D) Maximum demand / plant capacity
Ans: D

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Q31. Voltage drop in AC distributors is more than DC due to:
A) Resistance
B) Reactance
C) Both R and X
D) Capacitance
Ans: C

Q32. In rural areas, distribution voltage is generally:
A) 415 V
B) 6.6 kV
C) 11 kV
D) 33 kV
Ans: C

Q33. The most economical size of conductor is obtained by:
A) Kelvin’s law
B) Ohm’s law
C) Faraday’s law
D) Lenz’s law
Ans: A

Q34. Maximum demand can be reduced by:
A) Improving power factor
B) Load shifting
C) Demand side management
D) All of the above
Ans: D

Q35. The unit of demand factor is:
A) kVA
B) kW
C) Percentage
D) Dimensionless
Ans: D

Q36. The main function of a distribution substation is:
A) Stepping up voltage
B) Stepping down voltage
C) Power generation
D) Frequency control
Ans: B

Q37. Distribution lines are designed for:
A) Constant current
B) Constant voltage
C) Constant frequency
D) Constant power
Ans: B

Q38. The voltage regulation of a good distribution system should be within:
A) ±2%
B) ±5%
C) ±10%
D) ±15%
Ans: B

Q39. Power factor correction improves:
A) Voltage profile
B) Transmission efficiency
C) Reduces losses
D) All of the above
Ans: D

Q40. A balanced 3-phase load draws:
A) Equal current in all lines
B) Zero neutral current
C) Constant power
D) All of the above
Ans: D

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Q41. Which of the following is NOT a distribution system?
A) Radial
B) Ring main
C) Interconnected
D) Star-delta
Ans: D

Q42. The most economical distribution PF is:
A) 0.707
B) 0.8
C) 0.9
D) Unity
Ans: D

Q43. Peak load on a station is 100 MW, average load is 60 MW. The load factor is:
A) 0.4
B) 0.6
C) 0.75
D) 0.9
Ans: B

Q44. The reserve kept on running machines is called:
A) Cold reserve
B) Spinning reserve
C) Hot reserve
D) Operational reserve
Ans: B

Q45. For small towns, distribution is generally:
A) Underground ring
B) Overhead radial
C) Mesh
D) DC network
Ans: B

Q46. Ferranti effect is significant in:
A) Short lines
B) Medium lines
C) Long lightly loaded lines
D) DC systems
Ans: C

Q47. Reliability indices SAIFI and SAIDI are used in:
A) Power plants
B) Transmission
C) Distribution
D) Switchgear
Ans: C

Q48. A capacitor bank is connected at distribution end to:
A) Reduce PF
B) Improve PF
C) Reduce voltage
D) None
Ans: B

Q49. Losses in a distribution transformer are minimum at:
A) Full load
B) Half load
C) Load where copper = iron loss
D) No load
Ans: C

Q50. Voltage drop in a distributor depends on:
A) Load current
B) Power factor
C) Length of distributor
D) All of the above
Ans: D

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Q51. The demand factor of a load is:
A) Always >1
B) Always <1
C) Always =1
D) Can be >1 or <1
Ans: B

Q52. Three-phase 4-wire supply is used for:
A) Domestic consumers
B) Large industries
C) Transmission
D) Power plants
Ans: A

Q53. Which is not an advantage of high distribution voltage?
A) Reduced current
B) Reduced copper loss
C) Reduced insulation requirement
D) Improved efficiency
Ans: C

Q54. The main cause of poor power factor in distribution is:
A) Resistive load
B) Inductive load
C) Capacitive load
D) Balanced load
Ans: B

Q55. An interconnected distribution system provides:
A) Reliability
B) Flexibility
C) Voltage stability
D) All of the above
Ans: D

Q56. The plant capacity factor is always:
A) Greater than utilization factor
B) Less than utilization factor
C) Equal to utilization factor
D) None
Ans: B

Q57. A load having maximum demand of 50 kW and average load of 25 kW has LF =
A) 25%
B) 50%
C) 75%
D) 100%
Ans: B

Q58. The peak diversity factor of a system is always:
A) <1
B) >1
C) =1
D) 0
Ans: B

Q59. In a 3-phase 4-wire system, unbalanced loads cause:
A) Zero neutral current
B) Neutral current flow
C) Reduced efficiency
D) Both B & C
Ans: D

Q60. The choice of distribution voltage depends on:
A) Amount of power
B) Distance of supply
C) Economy
D) All of the above
Ans: D

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Q61. Radial system is not suitable for:
A) Short distances
B) Rural areas
C) Cities
D) Emergency supply
Ans: C

Q62. The utilization factor is:
A) Always > LF
B) Always < LF
C) Can be > or < LF
D) Equal to LF
Ans: A

Q63. The highest efficiency of distribution transformer occurs at:
A) Unity PF
B) Lagging PF
C) Leading PF
D) Independent of PF
Ans: D

Q64. A consumer uses 600 units in a month at a maximum demand of 2 kW. Load factor =
A) 0.25
B) 0.5
C) 0.75
D) 1
Ans: A

Q65. The cost of conductor material decreases with:
A) Increase in current
B) Increase in voltage
C) Decrease in voltage
D) Decrease in diversity factor
Ans: B

Q66. Which of the following is not a reliability index?
A) SAIFI
B) SAIDI
C) CAIDI
D) X/R ratio
Ans: D

Q67. The voltage profile of a distribution line can be improved by:
A) Shunt capacitors
B) Tap changing transformers
C) Series capacitors
D) All of the above
Ans: D

Q68. For the same load, copper loss is least in:
A) DC system
B) AC system
C) High voltage system
D) Low voltage system
Ans: C

Q69. If copper loss is 400 W at full load, then at half load it is:
A) 200 W
B) 100 W
C) 50 W
D) 400 W
Ans: B

Q70. Which improves load factor?
A) Peak load reduction
B) Increasing average load
C) Proper scheduling
D) All of the above
Ans: D

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Q71. Which tariff encourages higher load factor?
A) Flat rate
B) Two-part tariff
C) Maximum demand tariff
D) Power factor tariff
Ans: C

Q72. The connected load is 500 kW, maximum demand 300 kW. Demand factor =
A) 0.3
B) 0.5
C) 0.6
D) 0.7
Ans: C

Q73. For the same kVA, distribution transformers are designed to have:
A) High efficiency, low regulation
B) Low efficiency, high regulation
C) Low efficiency, low regulation
D) High iron loss
Ans: A

Q74. The hourly load curve helps in determining:
A) Energy consumed
B) Load factor
C) Maximum demand
D) All of the above
Ans: D

Q75. The unit for load factor is:
A) %
B) kW
C) kVA
D) Dimensionless
Ans: D

Q76. Which one is a secondary distribution voltage?
A) 400 V
B) 11 kV
C) 33 kV
D) 66 kV
Ans: A

Q77. A balanced 3-phase load supplied by 3-phase 4-wire system has neutral current:
A) Zero
B) Maximum
C) Equal to phase current
D) Infinite
Ans: A

Q78. Which type of load is most common in distribution?
A) Resistive
B) Inductive
C) Capacitive
D) Balanced
Ans: B

Q79. Voltage drop is proportional to:
A) Current only
B) Power factor only
C) Resistance only
D) I × (R cos φ + X sin φ)
Ans: D

Q80. A system supplying small industries usually uses:
A) 3-phase 3-wire
B) 3-phase 4-wire
C) DC 3-wire
D) Single-phase 2-wire
Ans: B

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Q81. In a distribution feeder, voltage is controlled by:
A) Voltage regulators
B) Shunt capacitors
C) On-load tap changers
D) All of the above
Ans: D

Q82. The annual load factor of an industrial consumer is generally:
A) 0.2 – 0.4
B) 0.5 – 0.7
C) 0.8 – 0.9
D) 0.9 – 1.0
Ans: B

Q83. The average load of a station is 30 MW, maximum demand is 60 MW. LF =
A) 0.25
B) 0.5
C) 0.75
D) 0.9
Ans: B

Q84. A 400/230 V system is a:
A) Primary distribution
B) Secondary distribution
C) Sub-transmission
D) Transmission
Ans: B

Q85. Copper loss in a distribution transformer at no load is:
A) Zero
B) Constant
C) Variable
D) Maximum
Ans: A

Q86. The phase difference between line current and voltage decides:
A) Efficiency
B) Power factor
C) Load factor
D) Diversity factor
Ans: B

Q87. The average demand divided by maximum demand is:
A) LF
B) UF
C) DF
D) PF
Ans: A

Q88. The substation which connects transmission and distribution is:
A) Primary substation
B) Secondary substation
C) Distribution substation
D) Grid substation
Ans: C

Q89. Which is not a load curve type?
A) Chronological
B) Load duration
C) Demand duration
D) Power duration
Ans: D

Q90. Higher load factor means:
A) Better utilization of plant
B) Poor economy
C) More maximum demand
D) Less energy generated
Ans: A

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Q91. For better load factor, utility companies encourage:
A) Load shifting
B) Time-of-day tariff
C) PF correction
D) All of the above
Ans: D

Q92. Which is not true for ring main distribution?
A) More reliable
B) Costlier
C) Voltage regulation is better
D) Requires less conductor length than radial
Ans: D

Q93. A 200 kW load supplied at 0.8 PF draws current:
A) More than unity PF
B) Less than unity PF
C) Same as unity PF
D) Infinite
Ans: A

Q94. Shunt capacitors installed in distribution lines mainly reduce:
A) Real power loss
B) Reactive power flow
C) Voltage
D) Frequency
Ans: B

Q95. Which load curve gives information about the number of hours a load is maintained?
A) Chronological curve
B) Load duration curve
C) Maximum demand curve
D) Plant capacity curve
Ans: B

Q96. In load curve analysis, area under the curve gives:
A) Maximum demand
B) Energy consumption
C) Average load
D) Load factor
Ans: B

Q97. Power loss in lines varies with:
A) V²
B) I²R
C) cos φ
D) sin φ
Ans: B

Q98. The main limitation of radial system is:
A) High cost
B) Poor reliability
C) Complex design
D) High maintenance
Ans: B

Q99. Interconnected systems reduce:
A) Reliability
B) Reserve capacity requirement
C) Efficiency
D) Flexibility
Ans: B

Q100. A good distribution system must have:
A) Proper voltage regulation
B) High reliability
C) Low losses
D) All of the above
Ans: D

 

POWER SYSTEM DISTRIBUTION – 100 MCQs 

Q1. The main function of a feeder in distribution is:
A) To deliver power to consumers directly
B) To connect substation to distributor
C) To reduce transmission loss
D) To step up voltage
Ans: B

Q2. In a distribution system, maximum voltage drop occurs in:
A) Feeder
B) Distributor
C) Service mains
D) Substation bus
Ans: B

Q3. The distributors are generally designed on the basis of:
A) Maximum current carrying capacity
B) Voltage drop
C) Loss minimization
D) Both A and B
Ans: D

Q4. For load centers far from substations, which distribution is preferred?
A) Radial
B) Ring main
C) Interconnected
D) Tree type
Ans: C

Q5. Voltage regulation is defined as:
A) Ratio of sending end voltage to receiving end voltage
B) Change in receiving end voltage from no-load to full-load
C) Losses in distribution
D) None
Ans: B

Q6. Distribution system reliability is measured by:
A) Losses
B) Outage frequency & duration
C) Load factor
D) Voltage drop
Ans: B

Q7. Which factor decides location of distribution transformer?
A) Distance of consumers
B) Load center
C) Voltage regulation
D) All of the above
Ans: D

Q8. The vector group of distribution transformer is usually:
A) Y-Y
B) Δ-Δ
C) Δ-Y
D) Y-Δ
Ans: C

Q9. The most common distribution conductor material is:
A) Copper
B) Aluminium
C) Steel
D) Aluminium with steel reinforcement
Ans: D

Q10. The voltage drop in a distributor is proportional to:
A) Current only
B) Resistance only
C) Current × resistance
D) Current² × resistance
Ans: C

Q11. Load factor is defined as:
A) Maximum demand / Average load
B) Average load / Maximum demand
C) Maximum demand / Connected load
D) Average load / Connected load
Ans: B

Q12. Demand factor is always:
A) Less than 1
B) Equal to 1
C) Greater than 1
D) Zero
Ans: A

Q13. Diversity factor is always:
A) < 1
B) = 1
C) > 1
D) 0
Ans: C

Q14. Which load has the lowest load factor?
A) Domestic
B) Commercial
C) Industrial
D) Agricultural
Ans: A

Q15. High load factor improves:
A) Efficiency
B) Reliability
C) Cost per unit
D) All of the above
Ans: D

Q16. Power factor correction in distribution reduces:
A) Real power
B) Current
C) Voltage
D) Frequency
Ans: B

Q17. Capacitors for distribution power factor improvement are usually installed at:
A) Substation
B) Consumer premises
C) Along the distributor
D) All of the above
Ans: D

Q18. In India, the permissible voltage variation at consumer end is:
A) ±1%
B) ±3%
C) ±5%
D) ±10%
Ans: C

Q19. The main advantage of interconnected system is:
A) Costlier
B) More reliable supply
C) Simple design
D) Less losses only
Ans: B

Q20. Which system requires more copper?
A) Radial
B) Ring main
C) Interconnected
D) Ring + Interconnected
Ans: B

Q21. Service mains are used to connect:
A) Substation to feeder
B) Feeder to distributor
C) Distributor to consumer
D) Transmission line to substation
Ans: C

Q22. A radial distributor is economical for:
A) Urban areas
B) Rural areas
C) Industrial load
D) Interconnected loads
Ans: B

Q23. In urban areas, the preferred system is:
A) Radial
B) Ring main
C) Tree system
D) DC system
Ans: B

Q24. The minimum permissible power factor at consumer end in India is:
A) 0.7
B) 0.8
C) 0.9
D) 1.0
Ans: B

Q25. A load curve represents:
A) Variation of voltage with time
B) Variation of load with time
C) Variation of frequency with time
D) None
Ans: B

Q26. The area under daily load curve represents:
A) Average load
B) Maximum load
C) Energy consumed
D) Demand factor
Ans: C

Q27. Annual load factor is always:
A) Less than unity
B) Equal to unity
C) Greater than unity
D) Zero
Ans: A

Q28. For the same maximum demand, higher load factor means:
A) Lower average load
B) Higher average load
C) Same average load
D) None
Ans: B

Q29. Plant capacity factor is defined as:
A) Average load / Plant capacity
B) Plant capacity / Average load
C) Plant capacity / Maximum demand
D) None
Ans: A

Q30. A good distribution system should have:
A) High efficiency
B) Reliability
C) Good voltage regulation
D) All of the above
Ans: D

Q31. Voltage unbalance in distribution system affects:
A) Transformers
B) Motors
C) Lighting loads
D) All of the above
Ans: D

Q32. Unbalanced loading in a 3-phase 4-wire system causes:
A) Harmonics
B) Neutral current
C) Overvoltage
D) Overfrequency
Ans: B

Q33. Which factor increases distribution losses?
A) High current
B) Low voltage
C) Poor power factor
D) All of the above
Ans: D

Q34. Skin effect is:
A) Concentration of current near conductor surface
B) Flow of current in conductor core
C) Increase in resistance with frequency
D) Both A and C
Ans: D

Q35. Proximity effect occurs due to:
A) Skin effect
B) Mutual induction between conductors
C) Resistance variation
D) Corona discharge
Ans: B

Q36. Corona effect in distribution lines is:
A) More at high voltage
B) More at low voltage
C) Independent of voltage
D) Negligible at 11 kV
Ans: D

Q37. Which device protects distribution lines from lightning?
A) Circuit breaker
B) Lightning arrester
C) Isolator
D) Fuse
Ans: B

Q38. Which device automatically isolates a faulty section of distribution?
A) Circuit breaker
B) Isolator
C) Fuse
D) All of the above
Ans: D

Q39. The most common earthing method in distribution is:
A) Plate earthing
B) Rod earthing
C) Pipe earthing
D) Any of the above depending on soil
Ans: D

Q40. Earth resistance should be:
A) Very high
B) Very low
C) Infinite
D) Zero
Ans: B

Q41. Which conductor arrangement gives minimum reactance?
A) Flat
B) Vertical
C) Transposed
D) Horizontal
Ans: C

Q42. Transposition of conductors is done to:
A) Reduce resistance
B) Reduce reactance imbalance
C) Reduce power factor
D) Reduce losses
Ans: B

Q43. The per-unit system is used in distribution to:
A) Normalize values
B) Simplify calculations
C) Compare systems of different ratings
D) All of the above
Ans: D

Q44. In rural distribution, the predominant load is:
A) Lighting
B) Irrigation pumps
C) Industrial motors
D) Commercial shops
Ans: B

Q45. Which equipment is used to stabilize voltage in distribution?
A) Tap changing transformer
B) Voltage stabilizer
C) Booster transformer
D) All of the above
Ans: D

Q46. Automatic load control in distribution is required to maintain:
A) Constant frequency
B) Constant voltage
C) Constant current
D) Constant power factor
Ans: A

Q47. Ferranti effect is:
A) Rise of receiving end voltage under light load
B) Fall of receiving end voltage under light load
C) Rise of sending end voltage
D) Fall of sending end voltage
Ans: A

Q48. Ferranti effect is more prominent in:
A) Short distribution lines
B) Long lightly loaded lines
C) Heavy load conditions
D) None
Ans: B

Q49. Which is NOT a method of voltage control in distribution?
A) Shunt capacitor
B) Tap changing transformer
C) Booster transformer
D) Induction motor
Ans: D

Q50. Arc suppression coil is used in:
A) Overcurrent protection
B) Earth fault protection
C) Lightning protection
D) Overvoltage protection
Ans: B

Q51. Automatic reclosing circuit breakers are used in distribution to:
A) Clear permanent faults
B) Clear transient faults
C) Maintain power factor
D) Improve efficiency
Ans: B

Q52. Distribution transformer rating is generally:
A) Above 1000 kVA
B) 25 kVA to 5000 kVA
C) Below 25 kVA
D) Above 10 MVA
Ans: B

Q53. No-load losses of distribution transformer are mainly due to:
A) Resistance
B) Leakage reactance
C) Core losses
D) Copper losses
Ans: C

Q54. Full-load losses in distribution transformer are mainly:
A) Core loss
B) Copper loss
C) Dielectric loss
D) Eddy current
Ans: B

Q55. Distribution transformer is designed for maximum efficiency at:
A) 25% load
B) 50% load
C) 75% load
D) Full load
Ans: C

Q56. Which type of transformer is mostly used in distribution?
A) Core type
B) Shell type
C) Auto transformer
D) Isolation transformer
Ans: B

Q57. The efficiency of distribution transformers is:
A) 50–60%
B) 60–70%
C) 90–98%
D) 40–50%
Ans: C

Q58. Vector group Dy11 of transformer means:
A) Delta primary, star secondary with 30° lag
B) Delta primary, star secondary with 30° lead
C) Star primary, delta secondary with 30° lag
D) Star primary, delta secondary with 30° lead
Ans: A

Q59. Pole-mounted distribution transformers are usually up to:
A) 25 kVA
B) 63 kVA
C) 250 kVA
D) 1000 kVA
Ans: C

Q60. Ground mounted distribution substations are usually:
A) 250 kVA and above
B) 100 kVA and below
C) 10 kVA only
D) None
Ans: A

Q61. Sectionalizers are used in distribution lines to:
A) Interrupt load current
B) Isolate faulty sections
C) Step down voltage
D) Improve power factor
Ans: B

Q62. A fuse is primarily used for:
A) Over-voltage protection
B) Over-current protection
C) Power factor improvement
D) Frequency stability
Ans: B

Q63. Rewirable fuses are also called:
A) High-rupturing capacity fuses
B) Kit-kat fuses
C) Cartridge fuses
D) Oil fuses
Ans: B

Q64. High rupturing capacity fuses are used for:
A) Low voltage only
B) High voltage systems
C) Both low and high voltage
D) None
Ans: B

Q65. The main limitation of fuse protection is:
A) Expensive
B) Cannot protect against short-circuit
C) After operation it must be replaced
D) None
Ans: C

Q66. Which breaker is most common in distribution?
A) Air circuit breaker
B) Oil circuit breaker
C) Vacuum circuit breaker
D) SF6 circuit breaker
Ans: C

Q67. Reclosers in distribution are mainly:
A) Air CB
B) Oil CB
C) Vacuum CB
D) All of the above depending on rating
Ans: D

Q68. Which relay is most common in distribution system?
A) Overcurrent relay
B) Differential relay
C) Distance relay
D) Directional relay
Ans: A

Q69. Ground fault relays are usually:
A) Instantaneous
B) Time delayed
C) Both
D) None
Ans: C

Q70. Distribution line insulators are mainly:
A) Pin type
B) Suspension type
C) Strain type
D) All depending on voltage
Ans: D

Q71. Pin type insulators are used up to:
A) 11 kV
B) 33 kV
C) 66 kV
D) 132 kV
Ans: B

Q72. Suspension insulators are preferred above:
A) 11 kV
B) 33 kV
C) 66 kV
D) 132 kV
Ans: C

Q73. Strain insulators are used for:
A) Line supports
B) Dead ends
C) Angle poles
D) Both B and C
Ans: D

Q74. Which distribution system has least copper requirement?
A) DC 2-wire
B) DC 3-wire
C) Single phase AC
D) Three phase 4-wire
Ans: D

Q75. Copper saving in 3-phase 4-wire system compared to DC 2-wire is about:
A) 25%
B) 33%
C) 50%
D) 75%
Ans: C

Q76. The main cause of low power factor in distribution is:
A) Heating loads
B) Motor loads
C) Lighting loads
D) All of the above
Ans: B

Q77. Power factor penalty is imposed on:
A) Residential loads
B) Commercial loads
C) Industrial loads
D) All of the above
Ans: C

Q78. Distribution automation helps in:
A) Load control
B) Fault detection
C) Remote switching
D) All of the above
Ans: D

Q79. SCADA in distribution means:
A) Supervisory Control and Data Acquisition
B) Super Control and Direct Automation
C) System Control and Data Analysis
D) None
Ans: A

Q80. Smart grid in distribution ensures:
A) Automatic fault isolation
B) Demand side management
C) Integration of renewable energy
D) All of the above
Ans: D

Q81. The smart meter measures:
A) Voltage only
B) Current only
C) Energy with time stamping
D) Frequency only
Ans: C

Q82. GIS in distribution means:
A) Gas Insulated Switchgear
B) Geographic Information System
C) Both depending on context
D) None
Ans: C

Q83. Ring main unit (RMU) is used in:
A) Transmission
B) Distribution
C) Generation
D) Protection only
Ans: B

Q84. RMU normally operates at:
A) 400 V
B) 11 kV
C) 33 kV
D) 66 kV
Ans: B

Q85. In India, maximum demand tariff is mainly applicable to:
A) Domestic consumers
B) Industrial consumers
C) Agricultural consumers
D) All consumers
Ans: B

Q86. TOD tariff means:
A) Tariff on demand
B) Tariff on duration
C) Time of Day tariff
D) Total optimum demand tariff
Ans: C

Q87. TOD tariff encourages:
A) Load shifting
B) Peak demand reduction
C) Better load factor
D) All of the above
Ans: D

Q88. Which load is considered as base load in distribution?
A) Lighting
B) Industrial
C) Residential
D) Commercial
Ans: B

Q89. Load duration curve is derived from:
A) Daily load curve
B) Monthly load curve
C) Annual load curve
D) Any load curve
Ans: A

Q90. The area under load duration curve gives:
A) Maximum demand
B) Energy consumed
C) Load factor
D) Diversity factor
Ans: B

Q91. Cold reserve in power system is:
A) Standby plant kept running
B) Standby plant kept off but available
C) Plant with zero efficiency
D) None
Ans: B

Q92. Hot reserve is:
A) Plant kept running but not loaded
B) Plant shut down
C) Plant running at full load
D) Plant with low efficiency
Ans: A

Q93. Spinning reserve is:
A) Extra generating capacity available on running machines
B) Standby machine not running
C) Unused capacity of transmission
D) None
Ans: A

Q94. Distribution reliability index SAIDI measures:
A) Frequency of interruptions
B) Duration of interruptions
C) Power factor
D) Voltage regulation
Ans: B

Q95. SAIFI measures:
A) Frequency of interruptions
B) Duration of interruptions
C) Energy consumption
D) Losses
Ans: A

Q96. CAIDI is defined as:
A) SAIDI/SAIFI
B) SAIFI/SAIDI
C) Energy/Load
D) Demand/Average load
Ans: A

Q97. Availability of distribution system is:
A) 1 – Outage time/Total time
B) Outage time/Total time
C) Load factor × Diversity factor
D) Reliability × Efficiency
Ans: A

Q98. Which reduces copper requirement?
A) High voltage distribution
B) Low voltage distribution
C) High current
D) Low power factor
Ans: A

Q99. EHVAC is usually not used for distribution because:
A) Corona loss
B) Insulation requirement
C) High cost
D) All of the above
Ans: D

Q100. A good distribution system must satisfy:
A) Reliability
B) Proper voltage regulation
C) Economy
D) All of the above
Ans: D

POWER SYSTEM DISTRIBUTION – MCQs

Q1. The usual primary distribution voltage in India is:
A) 400 V
B) 6.6 kV
C) 11 kV
D) 33 kV
Ans: C

Q2. The usual secondary distribution voltage in India is:
A) 110 V
B) 220/230 V
C) 400 V
D) 660 V
Ans: C

Q3. Distribution systems are generally designed for:
A) Constant current
B) Constant voltage
C) Variable frequency
D) None of the above
Ans: B

Q4. The distributor fed at one end only is called:
A) Radial distributor
B) Ring distributor
C) Double-fed distributor
D) Interconnected distributor
Ans: A

Q5. The distributor fed at both ends is called:
A) Radial distributor
B) Ring distributor
C) Double-fed distributor
D) Interconnected distributor
Ans: C

Q6. The distributor forming a closed loop is called:
A) Radial distributor
B) Ring main distributor
C) Interconnected distributor
D) None of these
Ans: B

Q7. Which system has the highest reliability?
A) Radial
B) Ring main
C) Interconnected
D) Both B and C
Ans: D

Q8. The common frequency of AC distribution in India is:
A) 25 Hz
B) 50 Hz
C) 60 Hz
D) 100 Hz
Ans: B

Q9. The load power factor in distribution systems is generally:
A) Unity
B) Lagging
C) Leading
D) Zero
Ans: B

Q10. For domestic consumers, supply is given by:
A) DC 3-wire
B) Single-phase 2-wire AC
C) Three-phase 3-wire AC
D) Three-phase 4-wire AC
Ans: D

Q11. Voltage drop in distribution is most affected by:
A) Line resistance
B) Line reactance
C) Power factor
D) All of the above
Ans: D

Q12. The size of a distributor is decided by:
A) Current carrying capacity
B) Voltage drop
C) Both A and B
D) None
Ans: C

Q13. The substation where distribution voltage is obtained from transmission voltage is:
A) Step-up substation
B) Step-down substation
C) Generating substation
D) None
Ans: B

Q14. The most common secondary distribution system is:
A) 1-phase, 2-wire
B) 1-phase, 3-wire
C) 3-phase, 3-wire
D) 3-phase, 4-wire
Ans: D

Q15. The most economical location of a distribution substation is:
A) Center of gravity of load
B) Far away from load
C) Near power plant
D) Near transmission line
Ans: A

Q16. In ring main system, if one section fails:
A) Whole system fails
B) Only that section is cut off
C) Supply is maintained from other side
D) None
Ans: C

Q17. Feeder size is determined by:
A) Current carrying capacity
B) Voltage drop
C) Power factor
D) Frequency
Ans: A

Q18. Distributor size is determined by:
A) Current carrying capacity
B) Voltage drop
C) Both A and B
D) Frequency
Ans: C

Q19. A feeder is:
A) Part of transmission system
B) Part of distribution system
C) Connector between source and distributor
D) Both B and C
Ans: D

Q20. The main disadvantage of radial system is:
A) Simplicity
B) Less reliability
C) Less maintenance
D) Economical
Ans: B

Q21. The interconnected system improves:
A) Reliability
B) Efficiency
C) Voltage regulation
D) All of the above
Ans: D

Q22. Load shedding is applied when:
A) Voltage increases
B) Power demand exceeds generation
C) Frequency is stable
D) None
Ans: B

Q23. Distribution lines generally use:
A) Underground cables
B) Overhead conductors
C) Both A and B
D) None
Ans: B

Q24. The voltage regulation of distribution system is better in:
A) Radial system
B) Ring main system
C) Interconnected system
D) Both B and C
Ans: D

Q25. Low voltage distribution for domestic purpose is usually:
A) 110 V
B) 220–240 V
C) 400 V
D) 660 V
Ans: B

Q26. High voltage distribution (for industries) is usually:
A) 400 V
B) 3.3 kV to 11 kV
C) 33 kV
D) 66 kV
Ans: B

Q27. The maximum permissible voltage drop in distribution systems is about:
A) 2%
B) 5%
C) 10%
D) 15%
Ans: B

Q28. Voltage drop is least in which distribution system?
A) Radial
B) Ring main
C) Interconnected
D) Both B and C
Ans: D

Q29. Power loss in distribution lines can be minimized by:
A) Using high voltage
B) Using low voltage
C) Increasing current
D) None
Ans: A

Q30. The efficiency of distribution system is maximum when losses are:
A) Equal to half of load
B) Equal to load
C) Minimum
D) Zero
Ans: C

Q31. The distributors for residential areas are:
A) Lightly loaded
B) Heavily loaded
C) Always DC
D) None
Ans: A

Q32. The distributors for industrial areas are:
A) Lightly loaded
B) Heavily loaded
C) Always AC
D) None
Ans: B

Q33. Which is cheaper for distribution?
A) DC
B) AC
C) Both same
D) Depends on load
Ans: B

Q34. Voltage fluctuations at consumer end cause:
A) Lamp flicker
B) Motor damage
C) Low efficiency
D) All of the above
Ans: D

Q35. The ring main system is preferred in:
A) Rural areas
B) Urban areas
C) Remote villages
D) None
Ans: B

Q36. Which one is NOT a distribution system?
A) Radial
B) Ring main
C) Interconnected
D) Star-delta
Ans: D

Q37. Distribution transformers usually have:
A) Delta-Delta connection
B) Star-Star connection
C) Delta-Star connection
D) Star-Delta connection
Ans: C

Q38. The frequency of supply in India is:
A) 25 Hz
B) 50 Hz
C) 60 Hz
D) 100 Hz
Ans: B

Q39. The efficiency of a good distribution system is about:
A) 60%
B) 70%
C) 80%
D) 90%
Ans: D

Q40. The most commonly used power factor improvement device in distribution is:
A) Capacitor
B) Inductor
C) Transformer
D) Synchronous motor
Ans: A

Q41. Underground distribution is more common in:
A) Cities
B) Villages
C) Hills
D) Remote areas
Ans: A

Q42. In India, the frequency tolerance allowed is:
A) ±5%
B) ±3%
C) ±1%
D) ±0.5%
Ans: A

Q43. Which is more reliable?
A) Overhead distribution
B) Underground distribution
C) Both same
D) None
Ans: B

Q44. The voltage of distribution system is stepped down from transmission voltage using:
A) Step-up transformer
B) Step-down transformer
C) Autotransformer
D) Phase transformer
Ans: B

Q45. The load curve of distribution shows:
A) Variation of current with time
B) Variation of voltage with time
C) Variation of load with time
D) None
Ans: C

Q46. Diversity factor of distribution system is always:
A) Less than 1
B) Equal to 1
C) Greater than 1
D) Zero
Ans: C

Q47. Maximum demand of a system is related to:
A) Average load
B) Connected load
C) Demand factor
D) All of the above
Ans: D

Q48. Power factor correction reduces:
A) Voltage
B) Current
C) Frequency
D) Resistance
Ans: B

Q49. The highest voltage used for distribution in India is:
A) 11 kV
B) 22 kV
C) 33 kV
D) 66 kV
Ans: C

Q50. A good distribution system should have:
A) Minimum losses
B) Good voltage regulation
C) Reliability
D) All of the above

Ans: D