Q.1
Armature coil is short circuited by brushes when it lies
Q.2
Satisfactory commutation of D.C. machines requires
Q.3
The e.m.f. generated in a D.C. generator is directly proportional to
Q.4
A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be
Q.5
Two generators are running in parallel. One of the generators may run as motor for which of the following reasons?
Q.6
The function of pole shoes in the case of D.C. machine is
Q.7
In case of a 4 pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be
Q.8
The resistance of armature winding depends on
Q.9
A D.C. welding generator has
Q.10
If a D.C. generator fails to build up the probable cause could not be
Q.11
Armature reaction of an unsaturated D.C. machine is
Q.12
Two generators A and B have 6 poles each. Generator A has wave wound armature while generator B has lap wound armature. The ratio of the induced e.m.f. is generator A and B will be
Q.13
A shunt generator can self-excite
Q.14
In a D.C. generator the critical resistance can be increased by
Q.15
In a D.C. machine, short-circuited field coil will result in
Q.16
In a level compounded D.C. generator, full load terminal voltage is
Q.17
The field coils of D.C. generator are usually made of
Q.18
A cumulatively compounded long shunt generator when operating as a motor would be
Q.19
If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by
Q.20
In a D.C. generator in case the resistance of the field winding is increased, then output voltage will
Q.21
In case of D.C. machines, mechanical losses are primary function of
Q.22
For the parallel operation of two or more D.C. compound generators, we should ensure that
Q.23
Eddy currents are induced in the pole shoes of a D.C. machine due to
Q.24
Welding generator will have
Q.25
In D.C. generators the pole shoes are fastened to the pole core by
Q.26
Which generator would you prefer for feeding long D.C. transmission lines?
Q.27
If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be
Q.28
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
Q.29
Which of the following generator will have negligible terminal voltage while running on no-load?
Q.30
To achieve sparkless commutation brushes of a D.C. generator are rockedm ahead so as to bring them
0 h : 0 m : 1 s