Deck 14: D.C Generators

Question 1

Number of tappings for each equilizer ring is equal to

A)number of pole pairs
B)number of poles
C)number of parallel paths
D)number of commutator segments

Answer 1

number of pole pairs

Question 2

A D.C. generator can be considered as

A)rectifier
B)primemover
C)rotating amplifier
D)power pump

Answer 2

rotating amplifier

Question 3

In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilised is called

A)rotor
B)stator
C)field
D)armature

Answer 3

armature

Question 4

In a D.C. machine stray loss is the sum of

A)total copper loss and mechanical loss
B)armature copper loss and iron loss
C)shunt field copper loss and mechanical loss
D)iron loss and mechanical loss

Question 5

Lap winding is composed of

A)any even number of conductors
B)any odd number of conductors
C)that even number which is exact multiple of poles + 2
D)that even number which is exact multiple of poles

Question 6

In a D.C. generator in case the resistance of the field winding is increased, then output voltage will

A)increase
B)decrease
C)remain unaffected
D)fluctuate heavily

Question 7

An exciter for a turbo generator is a

A)separately excited generator
B)shunt generator
C)series generator
D)compound generator

Question 8

In case of a flat compounded generator

A)voltage generated is less than the rated voltage
B)generated voltage is proportional to the load on the generator
C)voltage remains constant irrespec¬tive of the load
D)speed varies in proportion to the load on the generator

Question 9

Which of the following generator will have negligible terminal voltage while running on no-load ?

A)Series generator
B)Shunt generator
C)Compound generator
D)Separately excited generator

Question 10

Which of the following D.C. generators will be in a position to build up without any residual magnetism in the poles ?

A)Series generator
B)Shunt generator
C)Compound generator
D)None of the above

Question 11

In over compounded generator, full load terminal voltage is

A)almost zero
B)less than noload terminal voltage
C)more than noload terminal voltage
D)equal to no-load terminal voltage

Question 12

In a level compounded D.C. generator, full load terminal voltage is

A)negligibly low
B)equal to no-load terminal voltage
C)more than no-load terminal voltage
D)less than no-load terminal voltage

Question 13

The terminal voltage of a D.C. shunt generator drops on load because of all of the following reasons except

A)armature reaction
B)armature resistance drop
C)field weakening due to armature reaction and armature
D)commut ation

Question 14

In a D.C. generator

A)external resistance = internal char-acteristic - armature reaction
B)internal characteristic = magnetisation characteristic - ohmic drop
C)external characteristic = magnetisation characteristic - ohmic drop - armature reaction
D)magnetisation characteristic = external characteristic

Question 15

A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave

A)will be zero
B)will be of 5 Hz
C)willbeof5xiVHz
D)will be of v Hz 5

Question 16

A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be

A)zero
B)about 2 V
C)about 50 V
D)220V

Question 17

In a separately excited generator supplying rated load the armature reaction ,

A)is always present
B)is always absent
C)may be sometimes present
D)none of the above

Question 18

If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speedwill be

A)zero
B)small
C)the same as rated voltage
D)high

Question 19

Armature reaction in a generator results in

A)demagnetisation of leading pole tip and magnetisation of trailing pole tip
B)demagnetisation of trailing pole tip and magnetisation of leading pole tip
C)damagnetising the centre of all poles
D)magnetising the centre of all poles

Question 20

Following energized winding of a D.C. machine should not be opened as it would produce high inductive voltage which may be dangerous to personnel and may cause its own insulation failure.

A)Series field
B)Compensating field
C)Inter pole field
D)Shunt field

Question 21

Wave winding is composed of

A)any even number of conductors
B)any odd number of conductors
C)that even number which is exact multiple of poles + 2
D)that even number which is exact multiple of poles

Question 22

The critical resistance of the D.C. generator is the resistance of

A)field
B)brushes
C)armature
D)load

Question 23

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

Question 24

Which of the following generating machine will offer constant voltage on all loads ?

A)Self-excited generator
B)Separately excited generator
C)Level compounded generator .
D)All of the above

Question 25

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