In a circuit breaker the basic problem is to________________?

Related Mcqs:

1. Thermal circuit breaker has____________?

   A. delayed trip action
   B. instantaneous trip action
   C. both of the above
   D. none of the above

2. Magnetic circuit breaker has ___________ trip action

   A. delayed
   B. instantaneous
   C. both of the above
   D. none of the above

3. The arcing contacts in a circuit breaker are made of______________?

   A. copper tungsten alloy
   B. porcelain
   C. electrolytic copper
   D. aluminium alloy

4. Which of the following medium is employed for extinction of arc in air circuit breaker?

   A. Water
   B. Oil
   C. Air
   D. SF6

5. Air blast circuit breaker is used for_____________?

   A. over currents
   B. short duty
   C. intermittant duty
   D. repeated duty

6. The voltage appearing across the contacts after opening of the circuit breaker is called__________voltage

   A. recovery
   B. surge
   C. operating
   D. arc
   E. none of the above

7. Ionization in circuit breaker is facilitated by___________?

   A. high temperature
   B. increase of mean free path
   C. increasing field strength
   D. all of the above

8. The arc voltage produced in A.C. circuit breaker is always_____________?

   A. in phase with the arc current
   B. lagging the arc current by 90″
   C. leading the arc current by 90°
   D. none of the above

9. Arc in a circuit breaker is interrupted at___________?

   A. zero current
   B. maximum current
   C. minimum voltage
   D. maximum voltage

10. The information to the circuit breaker under fault conditions is provided by____________?

    A. relay
    B. rewirable fuse
    C. H.R.C. only
    D. all of the above