A. to avoid sudden loading of the primemover
B. to avoid mechanicaljerk to the shaft
C. to avoid burning of switch contacts
D. all above
Related Mcqs:
- 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 - In D.C. generators, the cause of rapid brush wear may be___________?
A. severe sparking
B. rough commutator surface
C. imperfect contact
D. any of the above - Which of the following statement about D.C. generators is false ?
A. Compensating winding in a D.C. machine helps in commutation
B. In a D. C. generator interpoles winding is connected in series with the armature winding
C. Back pitch and front pitch are both odd and approximately equal to the pole pitch
D. Equilizing bus bars are used with parallel running of D.C. shunt gen¬erators - 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 - In D.C. generators the polarity of the interpoles_____________?
A. is the same as that of the main pole ahead
B. is the same as that of the immediately preceding pole
C. is opposite to that of the main pole ahead
D. is neutral as these poles do not play part in generating e.m.f. - 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 - 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 - 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 - 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 - The essential condition for parallel operation of two D.C. generators is that they have ________________?
A. same kW rating
B. the same operation r.p.m.
C. the same drooping voltage characteristics
D. same percentage regulation
