PHYSICS: D.C. MACHINE 01/08 Online Test

Which type of D.c generator is used to charge the batteries .?
Shunt generator
Series generator
Long shunt compound generator
Any of the above
D.C. series generator application is limited to
Act as a booster to maintain constant voltage at the load end of the feeder
Supply fraction load
Supply industrial load at constant voltage
For none of the above purpose
If the number of poles in a wave wound generator is doubled then the generated emf will
Become half
Become double
Increase to four times
Remain constant.
If the number of poles in a lap wound generator be doubled, then the generated emf will
Become half
Become double
Increase to four times
Remain constant
Which of the following D.C generator can build up without any residual magnetism in the poles?
Compound generator
Self-excited generator
Series generator
Shunt generator
In a D.C. generator the actual flux distribution depends upon
Shape of the pole shoe
Size of air gap
Clearance between tips of the adjacent pole shoes
All of the above
In Ward Leonard control, the D.C motor is
Shunt motor
Series motor
Separately excited motor
Compound motor
If the voltage at a D.C shunt motor terminal is halved, load torque being the armature current will be
Halved
Doubled
Unaltered
Zero
Magnetic field in a D.C. generator is produced by
Permanent magnets
Electromagnets
Both (a) and (b)
None of the above
The polarity of a D.C. generator can be reversed by
Increasing field current
Reversing the field current
Reversing field current as well as direction of rotation
Any of the above
In a D.C machine, inter poles are used to
Generate more e.m.f. in the armature
Avoid interference of the armature flux with the main flux
Increase the demagnetizing effect of armature reaction
Neutralise the effect of armature reaction in the inter pole region
What is generally used to control the output voltage of a D.C generator
Speed
Load current
Excitation
Armature current
In D.C. generators, current to the external circuit from armature comes out from
Slip rings
Commutator
Brush connection
None of the above
The material for commutator is generally
Carbon
Mica
Copper
Cast iron
For spark less commutation the armature reaction effect in a D.C machine is neutralised by
Increasing the field excitation
Using compensating winding and commutating poles
Fixing the brush axis in alignment with the inter pole axis
Shifting the brush axis from GNA to MNA
The sparking at the brushes of a D.C generator is due to
Reactance voltage
Light load
Armature reaction
High resistance of the brushes.
Compensating windings are used in D.C. generators
To provide path for the circulation of cooling air
To neutralise the cross-magnetising effect of the armature reaction
Mainly to reduce the eddy currents by providing local short circuits
None of the above
While pole flux remains constant, if the speed of the generator is doubled, the e.m.f. Generated will
Half
Twice
Nominal value
Slightly less than nominal
What type of compounding would be desirable in. the D.C generator feeding a long transmission?
Over compounding
Under compounding
Flat compounding
Anyone of above
Which would have the highest percentage of voltage regulation?
Series generator
Shunt generator
Compound generator
Separately excited generator
The ripples in a D.C. generator are reduced by
Using equalizer rings
Using conductor of annealed copper
Using carbon brushes of superior quality
Using commutator with large number of segments
Description:

This is test is a part of a series of eight test which helps students to check the level of knowledge in Electricity, specifically in the DC Machine in Physics.

Discussion

Nallasingu Veerapavan

reading is the one of good thing

2492 days 16 hours 7 minutes ago

k.rama krishna

than u....

3348 days 23 hours 44 minutes ago

dheeraj

thanks for cocdeptual problms it clar my doubt

4027 days 19 hours 49 minutes ago

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