Power System Protection MCQs Part 10

a. Statement: Differential protection scheme should not be employed for longer transmission lines.

Logic: It is very expensive.

  1. Both statement and logic are wrong
  2. The statement is correct, but logic is incorrect
  3. The statement is incorrect, but logic is correct
  4. Logic defends the statement

Correct answer: 4. Logic defends the statement

b. The instantaneous relays used for earth fault detection in motors is usually set to _____________:

  1. 50% of the RLA
  2. 50% of the FLA
  3. 20% of the RLA
  4. 20% of the FLA

Correct answer: 4. 20% of the FLA

c. Declaration: Ground wires can easily protect the equipment from direct lightning thunders.

X: Ground wires are used to provide protection against traveling waves

  1. X is an application of declaration
  2. Both declaration and X are incorrect
  3. The declaration is correct, X is incorrect
  4. Declaration and X explain the same fact in different words

Correct answer: 3. The declaration is correct, X is incorrect

d. The method in which earthing is done through a transformer is referred as:

  1. Effective earthing
  2. Non-effective earthing
  3. Peterson coil earthing
  4. Flick method

Correct answer: 2. Non-effective earthing

e. The term non-effective earthing refers to the earthing which is done through:

  1. Resistance
  2. Reactance
  3. Transformer
  4. All of these

Correct answer: 4. All of these

f. Argument: Resistance earthing can’t be used for single phase loads.

Solution: Households always employ solid earthing.

  1. Argument and solution are not connected in the present context
  2. Argument leads to the solution
  3. The argument is wrong, the solution is correct
  4. Both solution and argument are wrong

Correct answer: 2. Argument leads to a solution

Explanation: The resistance earthing can’t be used for single phase loads due to which the solid earthing method is used by households.

g. Striker pin fuse is used for:

  1. LV circuits
  2. LV and MV circuits
  3. MV and HV circuits
  4. HV circuits

Correct answer: 2. LV and MV circuits

h. R.R.R.V depends on the:

  1. Inductance
  2. Capacitance
  3. Both of these
  4. None of these

Correct answer: 3. Both of these

i. The arc voltage is always _______________ the current:

  1. Leading
  2. Lagging
  3. In phase with

Correct answer: 3. In phase with

j. If the time required to reach the peak value is 100 µsec and the peak re-striking voltage is 200 kV, then average RRRV is:

  1. 20 MV/µsec
  2. 2 kV/µsec
  3. 200 MV/µsec
  4. 20 kV/µsec

Correct answer: 2. 2 kV/µsec

Continue reading:

Leave a Reply