Question 1

On which of the following effects of electric current a fuse operates ?
A)Photoelectric effect
B)Electrostatic effect
C)Heating effect
D)Magnetic effect

Accepted Answer

A fuse operates based on the heating effect of electric current. When the current exceeds a certain limit, the fuse wire heats up and melts, breaking the circuit to prevent damage to the electrical system.

Question 2

An isolator is installed
A)to operate the relay of circuit breaker
B)as a substitute for circuit breaker
C)always independent of the position of circuit breaker
D)generally on both sides of a circuit breaker

Accepted Answer

Isolators are generally installed on both sides of a circuit breaker to ensure that a section of the circuit can be completely disconnected for maintenance or repair, ensuring the safety of personnel. They are not substitutes for circuit breakers but work in conjunction with them to isolate parts of the circuit.

Question 3

A fuse in a motor circuit provides protection against
A)overload
B)short-circuit and overload
C)open circuit, short-circuit and overload
D)none of the above

Accepted Answer

A fuse in a motor circuit is designed to provide protection against both short-circuit and overload conditions. Short-circuits can cause immediate and severe damage, while overloads, if sustained, can cause overheating and eventual failure of the motor.

Question 4

Protection by fuses is generally not used beyond
A)20 A
B)50 A
C)100 A
D)200 A

Accepted Answer

Fuses are typically used for lower current ratings, generally up to 100 A, beyond which circuit breakers are preferred for better reliability and ease of resetting.

Question 5

A fuse is never inserted in
A)neutral wire
B)negative of D.C. circuit
C)positive of D.C. circuit
D)phase dine

Accepted Answer

A fuse is never inserted in the neutral wire because the neutral wire is not carrying any current.

Quiz 4: Electrical Protection and Circuit Breakers

On which of the following effects of electric current a fuse operates ?

An isolator is installed

A fuse in a motor circuit provides protection against

Protection by fuses is generally not used beyond

A fuse is never inserted in