1. What is the primary quenching medium used in air break circuit breakers?
(a). Water
(b). boil
(c). air
(d). hydrogen
2. Which risk is eliminated by using air break circuit breakers instead of oil-based systems?
(a). electric shock
(b). fire hazards
(c). mechanical stress
(d). arc spreading
3. What is the advantage of air over oil as a quenching medium in air break circuit breakers?
(a). Greater arc quenching properties
(b). elimination of mechanical stress
(c). low maintenance costs
(d). absence of fire risks
4. Which type of air break circuit breaker is limited to approximately 500 volts and lower-power circuits?
(a). Magnetic blow-out type
(b). plain brake type
(c). Arc-shoot type
(d). hydrogen type
5. What is the function of blow-out coils in magnetic blow-out type air break circuit breakers?
(a). produce hydrogen gas
(b). assist in extinguishing the arc
(c). increase breaking capacity
(d). control convection currents
6. In which type of air break circuit breaker the main contacts are used to flow current in the closed position?
(a). Plain brake type
(b). Magnetic blow out type
(c). Arc-shoot type
(d). hydrogen type
7. What is the purpose of connecting contacts in arc-shoot air break circuit breakers?
(a). extinguish the arc
(b). Protect main contacts from damage caused by arcing
(c). control convection currents
(d). increase breaking capacity
8. During a fault, which contacts in an arc-shoot air break circuit breaker operate first?
(a). Arcing the contacts.
(b). main contact
(c). Blow-out coils
(d). Hydrogen contact
9. What forces pull the arc upward in air break circuit breakers during a fault?
(a). convection currents
(b). mechanical stress
(c). hydraulic force
(d). magnetic and thermal forces
10. Where are air break circuit breakers usually installed?
(a). on horizontal panels outside
(b). on outside vertical panels
(c). indoors on horizontal panels
(d). indoors on vertical panels
11. In which applications is the use of an air break circuit breaker recommended?
(a). Where oil decline is a matter of concern
(b). where mechanical stress is required
(c). Where the risk of explosion is a concern
(d). where hydrogen gas is used
12. Over which voltage range are air break circuit breakers employed for DC applications?
(a). up to 500 volts
(b). up to 11 KV
(c). up to 15 KV
(d). up to 12,000 volts
13. What can happen to an air brake circuit breaker as the operating voltage and breaking capacity increases?
(a). It becomes lighter and simpler
(b). It becomes heavier, more complex and may not be suitable for modern power systems
(c). it remains unchanged
(d). it becomes more cost effective
14. What is the primary disadvantage of plain break type air break circuit breakers?
(a). limited breaking capacity
(b). slow process and possible arc propagation
(c). high maintenance costs
(d). Inability to handle low-power circuits
15. What role do convection currents play in a plane break type air break circuit breaker?
(a). extinguish the arc
(b). lengthen the arc
(c). increase breaking capacity
(d). control mechanical stress
16. Which type of air break circuit breaker does not use a blow-out coil?
(a). Plain brake type
(b). Magnetic blow-out type
(c). Arc-shoot type
(d). Blow-out coil is used in all types
17. What does the arc shoot efficiently do in an arc-shoot air break circuit breaker during a fault?
(a). produce hydrogen gas
(b). Limit, control and cool the arc
(c). lengthen the arc
(d). increase breaking capacity
18. What is the primary function of the blow-out coils in magnetic blow out type air break circuit breakers?
(a). Increase breaking capacity
(b). produce hydrogen gas
(c). lengthen the arc
(d). control convection currents
19. Which mechanism is employed to draw the arc between the arcing contacts during a fault?
(a). convection currents
(b). electromagnetic force and thermal action
(c). mechanical stress
(d). hydraulic force
20. Why are air break circuit breakers recommended for applications where the risk of explosion is a concern?
(a). They produce hydrogen gas
(b). They eliminate the risk of fire
(c). They are light weight
(d). They use oil as a medium to extinguish fires.
21. What are the disadvantages of using an air break circuit breaker at elevated pressure?
(a). increased breaking capacity
(b). low efficiency
(c). low maintenance costs
(d). better security
22. What type of circuit breaker is recommended for modern electrical systems with high operating voltages?
(a). Air Break Circuit Breaker
(b). Oil based circuit breaker
(c). Gas Circuit Breaker
(d). vacuum circuit breaker