Related Questions

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
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
For the parallel operation of two or more D.C. compound generators, we should ensure that
A Voltage of the incoming generator should be same as that of bus bar
B Polarity of incoming generator should be same as that of bus bar
C All the series fields should be run in parallel by means of equalizer connection
D Series fields of all generators should be either on positive side or negative side of the armature
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
If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens
A This will make armature to take heavy current, possibly burning it
B This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
C Nothing will happen to motor
D Motor will come to stop
If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens
A Nothing will happen to the motor
B This will make armature to take heavy current, possibly burning it
C This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
D Motor will run at very slow speed
Which of the following generators will be preferred if they are required to be run in parallel?
A Shunt generators
B Series generators
C Compound generators
D None of the above
When two D.C. series generators are running in parallel, an equalizer 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 armature reaction of both machines
When two D.C. generators are running in parallel an equalizer bar is used
A To increase the series flux
B To increase the generated e.m.f.
C To reduce the combined effect of armature reaction of both the machines
D So that the two identical machines will pass approximately equal currents to the load
A conditionally stable system is stable for the value of gain between two critical values. It is unstable if
A The gain is increased beyond upper critical value
B The gain is decreased below lower critical value
C Both A and B
D None of the above

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