Circuit Breaker Questions and Answers for Viva

Answer-1: Circuit Breaker is a mechanical device designed to close or open contact members, thus closing or opening an electrical circuit under the normal or abnormal conditions. It serves as an automatic safety device that detects abnormal current conditions and interrupts the flow of electricity to prevent damage to the circuit and associated equipment.

Answer-2: Circuit breakers can be reset after they trip, while fuses must be replaced once they have blown.

Answer-3: The main components of a circuit breaker include the contacts, operating mechanism, trip unit, and housing.

Answer-4: The contacts in a circuit breaker are responsible for making or breaking the electrical circuit.

Answer-5: Circuit breakers are available in different types, including thermal, magnetic, and thermal-magnetic and electronic circuit breakers

Answer-6: Yes, after a circuit breaker trips due to a fault, it can be manually reset by first moving it to the ‘off’ position and then back to the ‘on’ position.

Answer-7: Switch is just a device when can be able to open and close the circuit during normal operation. Whereas on the other hand circuit breaker has the ability to open and close the contacts during abnormal or fault conditions.

Answer-8: A single-pole circuit breaker interrupts only one conductor, while a double-pole circuit breaker interrupts both conductors simultaneously.

Answer-9: Circuit breakers are rated based on their voltage, current capacity, interrupting capacity, and type of load they can handle.

Answer-10: The interrupting capacity of a circuit breaker is the maximum fault current that it can safely interrupt without sustaining damage.

Answer-11: Circuit breakers can trip due to overload, short circuit, or ground fault conditions.

Answer-12: A ground-fault circuit interrupter is a type of circuit breaker that detects ground faults and quickly interrupts the circuit to prevent electric shock.

Answer-13: GFCIs are typically installed in areas where water and electricity are present, such as bathrooms, kitchens, and outdoor outlets.

Answer-14: An arc-fault circuit interrupter is a type of circuit breaker that detects dangerous electrical arcs and interrupts the circuit to prevent fires.

Answer-15: A GFCI detects ground faults, while an AFCI detects dangerous electrical arcs.

Answer-16: The making capacity of the circuit breaker when closed on a short circuit is the peak value of the maximum current wave (including dc component) in the first cycle of the current after the circuit is closed by the circuit breaker.

Answer-17: Current chopping is not common in oil circuit breakers because in most of the oil circuit breakers the arc extinguishing power is proportional to the magnitude of current to be interrupted.

Answer-18: Copper-Bismuth, Copper-lead, Copper-tellurium, Silver-bismuth, Silver-lead and Silver-tellurium are some of the alloys employed as contact materials in the vacuum circuit breakers.

Answer-19: The current chopping is considered as serious drawback because it sets up high voltage transient across the breaker contacts.

Answer-20: Circuit breakers help prevent electrical fires and electrocution by quickly interrupting the flow of current in the event of a fault or overload.