Electrical Power Transmission MCQs Part 29

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Electrical Engineering MCQs on Power Transmission Part 29

In DC transmission, the skin effect is

In DC transmission, the skin effect is:

  1. Zero
  2. Small
  3. Large
  4. Dependent on voltage level

Correct answer: 1. Zero

Explanation: In case of DC system the direct current is uniformly distributed over the whole X-section of the conductor. Therefore a DC system has no skin effect and the entire cross-section of line conductor is completely utilized.

The capacitance of transmission line is

The capacitance of transmission line is:

  1. Series element
  2. Shunt element
  3. Shunt-series element
  4. None of these

Correct answer: 2. Shunt element

For unity Power Factor (PF) the voltage regulation of short transmission line is

For unity Power Factor (PF) the voltage regulation of short transmission line is:

  1. IR
  2. IXL
  3. I (XL + R)
  4. XL/R

Correct answer: 1. IR

Explanation:

Formula for Voltage regulation (VR) = Vs -VR = IR cosΦR  + IXL sinΦR

In case of unity PF:

cosΦR = 1

sinΦR = 0

Therefore voltage regulation = IR

Sag of transmission line is least affected due to

Sag of transmission line is least affected due to:

  1. Atmospheric temperature
  2. Current through conductor
  3. Ice deposition on conductor
  4. Weight of conductor

Correct answer: 2. Current through conductor

Also see: Sag Formula and Calculations in Transmission Lines

The correct statement about voltage drop in AC and DC distribution systems is

The correct statement about voltage drop in AC and DC distribution systems is

  1. In AC distribution system voltage drop is due to resistance only
  2. In AC distribution system the effect of inductance is always neglected
  3. In DC distribution system the voltage drop is due to resistance only
  4. None of these

Correct answer: 3. In DC distribution system voltage drop is due to resistance only

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