In D.C. generators on no-load, the air gap flux distribution in space is______________?

Related Mcqs:

1. As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately______________?

   A. 40 percent
   B. 25 percent
   C. 10 percent
   D. 5 percent

2. Two generators are running in parallel. One of the generators may run as motor for which of the following reasons ?

   A. The direction of that generator is reversed
   B. The speed of that generator is increased
   C. The field of that generator is weakened
   D. That generator takes large share of loads

3. Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be_____________________?

   A. 270 V
   B. 267.5 V
   C. 265 V
   D. 257.4 V

4. In D.C. generators, current to the external circuit from armature is given through_____________?

   A. commutator
   B. solid connection
   C. slip rings
   D. none of above

5. In D.C. generators, the brushes on commutator remain in contact with conductors which_________________?

   A. lie under south pole
   B. lie under north pole
   C. lie under interpolar region
   D. are farthest from the poles

6. In D.C. generators, lap winding is used for______________?

   A. high voltage, high current
   B. low voltage, high current
   C. high voltage, low current
   D. low voltage, low current

7. When two D.C. series generators are running in parallel, an equilizer bar is used________________?

   A. to increase the speed and hence generated e.m.f.
   B. to increase the series flux
   C. so that two similar machines will pass approximately equal currents to the load
   D. to reduce the combined effect of ar-mature reaction of both machines

8. When two D.C. generators are running in parallel an equilizer bar is used______________?

   A. to increase the series flux
   B. to increase the generated e.m.f.
   C. to reduce the combined effect of ar-mature reaction of both the machines
   D. so that the two identical machines will pass approximately equal cur¬rents to the load

9. Shunt generators are most suited for stable parallel operation because of their______________?

   A. rising voltage characteristics
   B. identical voltage characteristics
   C. drooping voltage characteristics
   D. linear voltage characteristics

10. The main factor which leads to unstable parallel operation of flat and over compounded generators is_____________?

    A. their rising voltage characteristics
    B. unequal number of turns in their series field windings
    C. unequal speed regulation of their primemovers
    D. unequal series field resistances