power-system-protection-mcqs-part-7

Power System Protection MCQs Part 7

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a. The selectivity of the system is increased by:

  1. Considering the system as a single block
  2. Dividing the system into various protection zones
  3. Dividing system into two large blocks
  4. None of these

Correct answer: 2. Dividing the system into various protection zones

b. The protection system which compares the electrical quantity which enters and leaves any zone and then operates is:

  1. Balanced voltage
  2. Balanced current
  3. Differential protection system
  4. All of these

Correct answer: 4. All of these

c. Solkor unit protection is used with ________________:

  1. Stranded nonmetallic buses
  2. Solid metallic pilot wires
  3. Induction motors
  4. Transformers

Correct answer: 2. Solid metallic pilot wires

d. For safe operations, the transformer oil should have a minimum dielectric strength of:

  1. 10 KV
  2. 20 kV
  3. 50 kV
  4. 100 KV

Correct answer: 3. 50 kV

e. The protection relay which has inherent directional characteristics:

  1. Mho relay
  2. Reactance relay
  3. Distance relay
  4. All of these

Correct answer: 1. Mho relay

f. The magnetic circuit breaker has:

  1. Instantaneous working action
  2. Delays working action
  3. Both of these
  4. None of these

Correct answer: 1. Instantaneous working action

g. The correct statement about the unbalanced condition in alternator:

  1. The same current flows through different phases in the unbalanced alternator
  2. Unbalanced loading is not dangerous for the alternator
  3. Unbalanced loading introduces eddy current in the alternator
  4. None of these is correct

Correct answer: 3. Unbalanced loading introduces eddy current in the alternator

h. The circuit breaker which produces least arc energy:

  1. Air Blast
  2. Air break
  3. Bulk oil
  4. Plain oil

Correct answer: 1. Air Blast

i. The correct statement about Buchholz relay

  1. It can only be used with largely sized alternators
  2. It is installed with largely sized transformers which have no conservator tank
  3. It can detect incipient faults
  4. It should never be used with oil immersed transformers

Correct answer: 3. It can detect incipient faults

j. Generally, earth relays have _____________ current setting:

  1. Lower
  2. Higher

Correct answer: 1. Lower

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