electrical-power-transmission-mcqs-part-10

Electrical Power Transmission MCQs Part 10

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1. The advantage of DC system over AC systems:

  1. Skin effect is absent
  2. Smaller corona
  3. Inductive and capacitive losses are absent
  4. All of these
  5. None of these

Correct answer: 4. All of these

2. During insulator grading for improving string efficiency:

  1. Top unit has minimum capacitance
  2. Bottom unit has minimum capacitance
  3. Central unit has minimum capacitance
  4. All units have equal capacitance

Correct answer: 1. Top unit has minimum capacitance

3. The major disadvantage of insulator grading for improving string efficiency:

  1. It sparks corona
  2. Different sizes of units
  3. It is only 15% efficient
  4. Skin effect increases

Correct answer: 2. Different sizes of units

4. Excitation control method provides acceptable results for:

  1. Short transmission lines
  2. Medium transmission lines
  3. Long transmission lines
  4. None of above

Correct answer: 1. Short transmission lines

5. Pin insulators are recommended for voltages up to:

  1. 3.3 kV
  2. 11 kV
  3. 33 kV
  4. 138 kV

Correct answer: 3. 33 kV

6. Role of steel wire in ACSR is to:

  1. Improve mechanical strength
  2. Reduce skin effect
  3. Minimize corona losses
  4. Reduce inrush currents

Correct answer: 1. Improve mechanical strength

7. Stringing charts are used for:

  1. Determining the efficiency of string
  2. Evaluating holding strength of towers
  3. Sag calculations of conductors
  4. Determining the wind impact on conductors

Correct answer: 3. Sag calculations of conductors

8. Proximity effect in transmission lines exists due to:

  1. Stranded conductors
  2. Earth wire
  3. Adjacent conductors
  4. None of above

Correct answer: 3. Adjacent conductors

9. Each disc in suspension in suspension type insulator holds:

  1. 5 kV
  2. 11 kV
  3. 29 kV
  4. 43 kV

Correct answer: 2. 11 kV

10. The voltage across a 12 disc string is 132 kV. The voltage across lowest disc (nearest to the conductor) is 13 kV. Find the efficiency of string.

  1. 19%
  2. 80%
  3. 84%
  4. 118%

Correct answer: 3. 84%

Solution: String efficiency = Voltage across string / [No of insulators * Voltage across lowest disc]

= 132 / [13 * 12] = 0.84

Percentage of efficiency = 0.84 * 100 = 84%

List of All: Electrical Power Transmission MCQs

Previous Electrical Power Transmission MCQs Part 1

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