DBATU Model MCQ - Protection & Switchgear Engineering

Welcome to your Protection And Switchgear Engineering, dated April 22, 2021

1. When does the circuit breaker operate in the line?Deselect Answer

When power is to be supplied.

When the line is to be tested.

Whenever the fault occurs in the line.

Whenever the switch and the relay has to be operated.

2. Which material is used for the manufacture of bus bars?Deselect Answer

Aluminium rods.

Copper rods.

Any conducting material.

Made of silver.

3. Which among these are the main characteristics of a fuse element?Deselect Answer

Low melting point

High conductivity

Least deterioration due to oxidation

All of the above

4. Which among these is the least expensive protection for over current in low voltage system?Deselect Answer

Rewirable fuse.

Isolator.

Circuit breaker.

Air breaker switch.

5. What is the maximum current upto which fuses can be used?Deselect Answer

25 A

75 A

1 25 A

100 A

6. Which among these tests are performed to check the nation or international standards?Deselect Answer

Type test.

Production tests.

Site checks.

All of the above.

7. What is the cut off current in the fuse?Deselect Answer

Maximum value actually reached.

Rms value actually reached.

Average value actually reached.

None of the above

8. Which type of tripping is generally preferred for the circuit breaker?Deselect Answer

Manual

Automatically

Depending on the voltage level

None of the above

9. How is the initiation of electric arc at the instant of contact separation caused?Deselect Answer

Thermionic emission of electrons.

Field emission of electrons.

Both (a) and (b)

None of these.

10. The heat produced at the contact point owing to flow of electric current is least affected by_____________________.Deselect Answer

Temperature of the surrounding medium.

Contact resistance.

Magnitude of electric current flowing.

Duration of flow of current.

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