Electrical Installation & Maintenance MCQ Test-03

#1. A lightning arrester provides

A. Low impedance path

B. High impedance path

C. Low resistance path

D. High resistance path between line and earth during operation

Explanation: Lightning arresters protect electrical equipment by providing a low-impedance path for lightning current to flow harmlessly to ground, preventing damage to critical components

#2. The primary function of a lightning arrester is to:

A. Divert lightning current safely to ground.

B. Increase the voltage level in a power system.

C. Act as a fuse to interrupt excess current.

D. Store electrical energy for later use.

#3. What is the term used for the voltage at which a lightning arrester starts to conduct current?

A. Breakdown voltage

B. Rated voltage

C. Operating voltage

D. Surge voltage

Explanation: Breakdown voltage is the critical voltage level at which the arrester transitions from its high-impedance state to a low-impedance state, allowing current to flow.

#4. Why is a changeover switch used in electrical systems?

A) To control the voltage of a circuit

B) To switch between different power sources during an outage

C) To regulate the current flow in a circuit

D) To measure the power consumption in a circuit

Explanation: A changeover switch is used to seamlessly switch between two power sources, like the main electricity grid and a backup generator, ensuring uninterrupted power supply during outages

#5. The contact resistance of a manually operated switch is

Zero

Very high

Very low

None of the above

#6. A switch should have

A. High insulation resistance

B. Low insulation resistance

C. Insulation resistance equal to contact resistance

D. None of the above

#7. The primary function of a fuse is to

A. Open the circuit

B. Protect the appliance

C. Protect the line

D. Prevent excessive currents from flow through the circuit

#8. fuse is never inserted in

A. Neutral wire

B. Negative of DC circuit

C. Positive of DC circuit

D. Phase line

#9. The fuse wire in DC circuit is inserted in

A. Negative circuit only

B. Positive circuit only

C. Both A and B

D. Either A or B

#10. A fuse in a motor circuit provides protection against

A. Overload

B. Short-circuit and overload

C. Open circuit, short-circuit and overload