Power System Transmission – Set 2 (Q51–Q100)

 

Power System Transmission – Set 2 (Q51–Q100)

Q51. Transmission lines are designed for:
A) Maximum current
B) Surge voltage
C) Surge impedance loading
D) Fault level
Ans: C

Q52. The corona loss decreases with:
A) Increase in conductor spacing
B) Increase in frequency
C) Increase in voltage
D) Increase in load
Ans: A

Q53. The natural load of a transmission line is also called:
A) Thermal loading
B) Surge impedance loading
C) Critical loading
D) Maximum power
Ans: B

Q54. Inductance of a transmission line is reduced by:
A) Decreasing conductor spacing
B) Increasing conductor spacing
C) Increasing conductor radius
D) Using ACSR
Ans: A

Q55. Kelvin’s law is used for:
A) Transformer design
B) Transmission line conductor size
C) Cable insulation thickness
D) Stability analysis
Ans: B

Q56. Overhead lines are generally supported by:
A) Wooden poles
B) Steel towers
C) Aluminium rods
D) Copper rods
Ans: B

Q57. Transposition of transmission lines equalizes:
A) Resistance
B) Capacitance and inductance
C) Conductor sag
D) Corona loss
Ans: B

Q58. Which of the following is a shunt compensator?
A) Series capacitor
B) Synchronous condenser
C) Series reactor
D) HVDC link
Ans: B

Q59. For maximum power transfer in transmission line:
A) Zs = Zr
B) Zs = Zr*
C) Zs = 0
D) Zs = ∞
Ans: B

Q60. Which insulator is used at dead-ends of lines?
A) Pin
B) Shackle
C) Strain
D) Suspension
Ans: C

Q61. The charging current in a transmission line is due to:
A) Resistance
B) Inductance
C) Capacitance
D) Conductance
Ans: C

Q62. Bundle conductors reduce:
A) Resistance
B) Inductance and corona
C) Capacitance
D) Mechanical strength
Ans: B

Q63. The transmission voltage is decided based on:
A) Line length and power
B) Load type
C) Frequency
D) Fault level
Ans: A

Q64. For a given conductor, sag is inversely proportional to:
A) Span length
B) Tension
C) Weight
D) Temperature
Ans: B

Q65. The effect of corona is more pronounced in:
A) Winter
B) Summer
C) Rainy
D) Clear weather
Ans: C

Q66. Which law gives the most economical cross-section of conductor?
A) Ohm’s law
B) Joule’s law
C) Kelvin’s law
D) Faraday’s law
Ans: C

Q67. The voltage drop in a transmission line is directly proportional to:
A) Load current
B) Line resistance and reactance
C) Power factor
D) All of these
Ans: D

Q68. In EHV transmission, shunt reactors are used to:
A) Increase voltage
B) Absorb charging VARs
C) Improve power factor
D) Suppress harmonics
Ans: B

Q69. The capacitance of a line increases with:
A) Larger conductor spacing
B) Smaller conductor spacing
C) Smaller conductor radius
D) Higher resistance
Ans: B

Q70. For high-voltage overhead lines, the most common insulator is:
A) Pin
B) Suspension
C) Strain
D) Shackle
Ans: B

Q71. Transposition is generally required in:
A) Short lines
B) Long lines
C) Distribution lines
D) LV feeders
Ans: B

Q72. The span length in overhead lines depends on:
A) Conductor size
B) Type of pole/tower
C) Line voltage
D) All of these
Ans: D

Q73. In a 3-phase line, inductance is equalized by:
A) Corona control
B) Line transposition
C) Bundle conductors
D) Sag-tension method
Ans: B

Q74. Transmission line efficiency is given by:
A) (Receiving power / Sending power) × 100
B) (Sending power / Receiving power) × 100
C) (Losses / Sending power) × 100
D) (Losses / Receiving power) × 100
Ans: A

Q75. The safe working voltage of a line depends on:
A) Corona
B) Sag
C) Insulators
D) Frequency
Ans: C

Q76. The surge impedance is also known as:
A) Characteristic impedance
B) Critical impedance
C) Corona impedance
D) Natural impedance
Ans: A

Q77. A tuned power line is one where:
A) Receiving voltage = Sending voltage
B) Receiving voltage > Sending voltage
C) Receiving current = Sending current
D) Sending end power = Receiving end power
Ans: A

Q78. A 220 kV line generally uses insulator discs of:
A) 3–4
B) 10–12
C) 20–22
D) 30–35
Ans: B

Q79. Shunt capacitors are used in transmission lines to:
A) Supply reactive power
B) Reduce inductive reactance
C) Improve voltage profile
D) All of these
Ans: D

Q80. The effect of resistance in transmission lines is to:
A) Reduce efficiency
B) Reduce voltage
C) Cause heating
D) All of these
Ans: D

Q81. For very long lines, the transmission line equation is solved using:
A) π-model
B) Hyperbolic functions
C) Equivalent resistance
D) Laplace transform
Ans: B

Q82. When a transmission line is short-circuited at receiving end, it behaves as:
A) Inductor
B) Capacitor
C) Resistance
D) Short wire
Ans: A

Q83. In modern EHV AC lines, voltage levels are generally:
A) 33–66 kV
B) 132–220 kV
C) 400–765 kV
D) >1000 kV
Ans: C

Q84. The power factor of no-load line is:
A) Leading
B) Lagging
C) Unity
D) Zero
Ans: A

Q85. Overhead transmission lines are preferable for:
A) Low cost
B) Easy maintenance
C) High voltage
D) All of these
Ans: D

Q86. In a DC line, the effect absent compared to AC line is:
A) Resistance
B) Inductance and capacitance
C) Corona
D) Voltage drop
Ans: B

Q87. A synchronous condenser connected at receiving end improves:
A) Active power
B) Reactive power
C) Efficiency
D) Frequency
Ans: B

Q88. The reflection coefficient of an open-ended line is:
A) +1
B) -1
C) 0
D) ∞
Ans: A

Q89. A lossless transmission line is one in which:
A) R=0, G=0
B) L=0, C=0
C) R=0, C=0
D) L=0, G=0
Ans: A

Q90. Surge impedance loading (SIL) increases with:
A) Conductor size
B) Frequency
C) Voltage level
D) Span length
Ans: C

Q91. Stability of a power system depends on:
A) Power angle δ
B) X of line
C) Voltage magnitude
D) All of these
Ans: D

Q92. The maximum power transfer occurs when:
A) δ = 90°
B) δ = 45°
C) δ = 0°
D) δ = 120°
Ans: A

Q93. Shunt reactors in long EHV lines are connected:
A) In series with line
B) Across line
C) In parallel with generators
D) None
Ans: B

Q94. The percentage resistance of a transmission line is usually:
A) 1–2%
B) 2–3%
C) 3–5%
D) 5–10%
Ans: A

Q95. Line insulators are tested for:
A) Mechanical strength
B) Electrical strength
C) Pollution resistance
D) All of these
Ans: D

Q96. HVDC transmission is mainly preferred for:
A) Short distance
B) Long distance bulk power
C) Rural supply
D) Distribution
Ans: B

Q97. The effect of proximity is to:
A) Increase resistance
B) Decrease resistance
C) Increase capacitance
D) Decrease inductance
Ans: A

Q98. Voltage regulation of a line is defined as:
A) (Vs - Vr)/Vr ×100
B) (Vr - Vs)/Vr ×100
C) (Is - Ir)/Ir ×100
D) (Pr - Ps)/Ps ×100
Ans: A

Q99. A 765 kV line is generally used for:
A) Urban distribution
B) Medium power transmission
C) Inter-state bulk transmission
D) Rural supply
Ans: C

Q100. The corona inception voltage increases with:
A) Higher altitude
B) Smooth conductor surface
C) Smaller conductor spacing
D) Higher humidity
Ans: B