Power System Protection MCQs Part 4

a. The basic purpose of a relay is to:

  1. Detect the fault
  2. Remove the fault
  3. Trip the circuit
  4. All of these

Correct answer: 1. Detect the fault

b. Statement: The induction relays operate on the principle of the induction motor.

Affirmation: Induction motors can’t be used with dc quantities.

  1. Both statement and affirmations are correct
  2. Both are wrong
  3. The statement is correct but affirmation is wrong
  4. The statement is wrong but affirmation is correct

Correct answer: 3. The statement is correct but affirmation is wrong

c. Buchholz relay is a _________ relay which is used for protection of _________:

  1. Gas actuated, transformers
  2. Gas actuated, generators
  3. Gas actuated, motors
  4. Digital, alternator

Correct answer: 1. Gas actuated, transformers

d. The Insulation test voltage should be done with the parameters:

  1. 2 kV, 50 Hz, 1 min
  2. 5 kV, 50 Hz, 5 min
  3. 10 kV, 50 Hz, 10 min
  4. 20 kV, 50 Hz, 20 min

Correct answer: 1. 2 kV, 50 Hz, 1 min

e. In Electrical power protection schemes ______________ transformer is used:

  1. VT
  2. CVT
  3. Both of these
  4. None of these

Correct answer: 3. Both of these

Explanation: VT stands for voltage transformer and CVT stands for capacitive voltage transformers

f. CVTs are often used to:

  1. Protection
  2. Instrumentation
  3. Communication
  4. All of these

Correct answer: 4. All of these

g. The equipment which has lowest chances of fault occurrence:

  1. Alternator
  2. Transformer
  3. Switchgear
  4. Induction motors

Correct answer: 1. Alternator

h. Single L – G fault is classified as:

  1. Symmetrical fault
  2. Unsymmetrical fault
  3. Linear fault
  4. None of these

Correct answer: 2. Unsymmetrical fault

i. Oil in a circuit breaker is used to:

  1. Quench arc
  2. Insulate the breaker contacts
  3. Increase the breaking capacity
  4. None of these

Correct answer: 1. Quench arc

j. The _______________ of circuit breaker is always greater than _____________:

  1. Symmetrical breaking capacity, Making capacity
  2. Making capacity, Symmetrical breaking capacity
  3. Making capacity, 50000 A
  4. None of these

Correct answer: 3. Making capacity, Symmetrical breaking capacity

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