Most Important Power System Protection MCQs
Electrical Engineering XYZ presents most important power system protection MCQs on important topics including fuses, relays, circuit breakers, machines, motors, transformers, alternator, grounding and protection schemes. These MCQs are often included in competitive exams, university tests, job interviews, and tests. Let’s start learning:
Contents
An overcurrent relay having a current setting of 150% is connected through a 400/5 CT. The pickup value of current is
a. An overcurrent relay having a current setting of 150% is connected through a 400/5 CT. The pickup value of current is:
- 2.5 A
- 5 A
- 7.5 A
- 10 A
Correct answer: 3. 7.5 A
Solution: 5 * 1.5 = 7.5 A
The instantaneous relays used for earth fault detection in motors is usually set to _____________
b. The instantaneous relays used for earth fault detection in motors is usually set to _____________:
- 50% of the RLA
- 50% of the FLA
- 20% of the RLA
- 20% of the FLA
Correct answer: 4. 20% of the FLA
The term effective earthing refers to the earthing which is done through
c. The term effective earthing refers to the earthing which is done through:
- Resistance
- Reactance
- Transformer
- None of these
Correct answer: 4. None of these
The component which provides a signal to circuit breaker under the fault condition
d. The component which provides a signal to circuit breaker under the fault condition:
- Isolator
- Fuse
- Relay
- CT
Correct answer: 3. Relay
The correct statement about Buchholz relay
e. The correct statement about Buchholz relay
- It can only be used with largely sized alternators
- It is installed with largely sized transformers which have no conservator tank
- It can detect incipient faults
- It should never be used with oil immersed transformers
Correct answer: 3. It can detect incipient faults
The breaking capacity of the circuit breaker is in _______ and is measured in ________
f. The breaking capacity of the circuit breaker is in _______ and is measured in ________:
- R.M.S, kVA
- R.M.S, MVA
- Peak, kVA
- Peak, MVA
Correct answer: 2. R.M.S, MVA
Semi-open cartridge type fuse can handle current up to ___________
g. Semi-open cartridge type fuse can handle current up to ___________:
- 1000 A
- 2500 A
- 4000 A
- 10000 A
Correct answer: 3. 4000 A
Interturn faults on an alternator are _________ and are ___________ detectable
h. Interturn faults on an alternator are _________ and are ___________ detectable:
- Common, easily
- Uncommon, easily
- Uncommon, not easily
- Common, not easily
Correct answer: 3. Uncommon, not easily
MCQ
i. Declaration: Ground wires can easily protect the equipment from direct lightning thunders.
X: Ground wires are used to provide protection against traveling waves
- X is an application of declaration
- Both declaration and X are incorrect
- The declaration is correct, X is incorrect
- Declaration and X explain the same fact in different words
Correct answer: 3. The declaration is correct, X is incorrect
Continue reading:
- Power System Protection MCQs Part 1
- Power System Protection MCQs Part 2
- Power System Protection MCQs Part 3
- Power System Protection MCQs Part 4
- Power System Protection MCQs Part 5
- Power System Protection MCQs Part 6
- Power System Protection MCQs Part 7
- Power System Protection MCQs Part 8
- Power System Protection MCQs Part 9
- Power System Protection MCQs Part 10