Question 1

The demagnetising component of armature reaction in a D.C. generator

Accepted Answer

A) reduces generator e.m.f. 
B) increases armature speed 
C) reduces interpoles flux density 
D) results in sparking trouble 
A) reduces generator e.m.f. 
B) increases armature speed 
C) reduces interpoles flux density 
D) results in sparking trouble A

Question 2

The voltage drop for which of the following types of brush can be expected to be least?

Accepted Answer

A) Graphite brushes 
B) Carbon brushes 
C) Metal graphite brushes 
D) None of the above 
A) Graphite brushes 
B) Carbon brushes 
C) Metal graphite brushes 
D) None of the above C

Question 3

Equilizer rings are required in case armature is

Accepted Answer

A) wave wound 
B) lap wound 
C) delta wound 
D) duplex wound 
A) wave wound 
B) lap wound 
C) delta wound 
D) duplex wound B

Question 4

Magnetic field in a D.C. generator is produced by

Accepted Answer

A) electromagnets 
B) permanent magnets 
C) both (a) and (b) 
D) none of the above 
A) electromagnets 
B) permanent magnets 
C) both (a) and (b) 
D) none of the above

Question 5

The material for commutator brushes is generally

Accepted Answer

A) mica 
B) copper 
C) cast iron 
D) carbon 
A) mica 
B) copper 
C) cast iron 
D) carbon

Question 6

Eddy currents are induced in the pole shoes of a D.C. machine due to

Accepted Answer

A) oscillating magnetic field 
B) pulsating magnetic flux 
C) relative rotation between field and armature 
D) all above 
A) oscillating magnetic field 
B) pulsating magnetic flux 
C) relative rotation between field and armature 
D) all above

Question 7

Armature reaction of an unsaturated D.C. machine is

Accepted Answer

A) crossmagnetising 
B) demagnetising 
C) magnetising 
D) none of above 
A) crossmagnetising 
B) demagnetising 
C) magnetising 
D) none of above

Question 8

If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be

Accepted Answer

A) demagnetisation only 
B) cross magnetisation as well as magnetisation 
C) crossmagnetisation as well as demagnetising 
D) cross magnetisation only 
A) demagnetisation only 
B) cross magnetisation as well as magnetisation 
C) crossmagnetisation as well as demagnetising 
D) cross magnetisation only

Question 9

A D.C. welding generator has

Accepted Answer

A) lap winding 
B) wave moving 
C) duplex winding 
D) All of the above 
A) lap winding 
B) wave moving 
C) duplex winding 
D) All of the above

Question 10

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 generatorA and B will be

Accepted Answer

A) 2 : 3 
B) 3 : 1 
C) 3 : 2 
D) 1 :3 
A) 2 : 3 
B) 3 : 1 
C) 3 : 2 
D) 1 :3

Question 11

For a D.C. machines laboratory following type of D.C. supply will be suitable

Accepted Answer

A) rotary converter 
B) mercury are rectifier 
C) induction motor D.C. generator set 
D) synchronous motor D.C. generator set 
A) rotary converter 
B) mercury are rectifier 
C) induction motor D.C. generator set 
D) synchronous motor D.C. generator set

Question 12

The insulating material used between the commutator segments is normally

Accepted Answer

A) graphite 
B) paper 
C) mica 
D) insulating varnish 
A) graphite 
B) paper 
C) mica 
D) insulating varnish

Question 13

D.C. generators are connected to the busbars or disconnected from them only under the floating condition

Accepted Answer

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 
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

Question 14

The number of brushes in a commutator depends on

Accepted Answer

A) speed of armature 
B) type of winding 
C) voltage 
D) amount of current to be collected 
A) speed of armature 
B) type of winding 
C) voltage 
D) amount of current to be collected

Question 15

The function of pole shoes in the case of D.C. machine is

Accepted Answer

A) to reduce the reluctance of the magnetic path 
B) to spread out the flux to achieve uniform flux density 
C) to support the field coil 
D) to discharge all the above functions 
A) to reduce the reluctance of the magnetic path 
B) to spread out the flux to achieve uniform flux density 
C) to support the field coil 
D) to discharge all the above functions

Question 16

In D.C. generators, the brushes on commutator remain in contact with conductors which

Accepted Answer

A) lie under south pole 
B) lie under north pole 
C) lie under interpolar region 
D) are farthest from the poles 
A) lie under south pole 
B) lie under north pole 
C) lie under interpolar region 
D) are farthest from the poles

Question 17

Welding generator will have

Accepted Answer

A) lap winding 
B) wave winding 
C) delta winding 
D) duplex wave winding 
A) lap winding 
B) wave winding 
C) delta winding 
D) duplex wave winding

Question 18

The e.m.f. generated by a shunt wound D.C. generator isE. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be

Accepted Answer

A) E/2 
B) 2E 
C) slightly less than E 
D) E 
A) E/2 
B) 2E 
C) slightly less than E 
D) E

Question 19

In the case of lap winding resultant pitch is

Accepted Answer

A) multiplication of front and back pitches 
B) division of front pitch by back pitch 
C) sum of front and back pitches 
D) difference of front and back pitches 
A) multiplication of front and back pitches 
B) division of front pitch by back pitch 
C) sum of front and back pitches 
D) difference of front and back pitches

Question 20

In a D.C. generator the ripples in the direct e.m.f. generated are reduced by

Accepted Answer

A) using conductor of annealed copper 
B) using commutator with large number of segments 
C) using carbon brushes of superior quality 
D) using equiliser rings 
A) using conductor of annealed copper 
B) using commutator with large number of segments 
C) using carbon brushes of superior quality 
D) using equiliser rings

The demagnetising component of armature reaction in a D.C. generator

The voltage drop for which of the following types of brush can be expected to be least?

Equilizer rings are required in case armature is

Magnetic field in a D.C. generator is produced by

The material for commutator brushes is generally

Eddy currents are induced in the pole shoes of a D.C. machine due to

Armature reaction of an unsaturated D.C. machine is

If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be

A D.C. welding generator has

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 generatorA and B will be

For a D.C. machines laboratory following type of D.C. supply will be suitable

The insulating material used between the commutator segments is normally

D.C. generators are connected to the busbars or disconnected from them only under the floating condition

The number of brushes in a commutator depends on

The function of pole shoes in the case of D.C. machine is

In D.C. generators, the brushes on commutator remain in contact with conductors which

Welding generator will have

The e.m.f. generated by a shunt wound D.C. generator isE. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be

In the case of lap winding resultant pitch is

In a D.C. generator the ripples in the direct e.m.f. generated are reduced by

Transformer Fundamentals and Operation

Transformer Technology and Design

Transformer: Resistance, Oil, Relays, Harmonics, and Core Properties

Transformers: Efficiency, Design, and Testing

Transformers: Voltage Regulation, Efficiency, and Protection

Transformer and D.C Motor

D.C Motors and Starters

D.C Motors and Speed Control

D.C Motors and Controls

D.C Motors and Generators

D.C Machine and Generator Laminations, Commutation, and Components

D.C Generator Operation and Construction

D.C Generators

Direct Current Generators and Parallel Operation

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Exam 12: D.C Generators and Commutators

The demagnetising component of armature reaction in a D.C. generator

The voltage drop for which of the following types of brush can be expected to be least?

Equilizer rings are required in case armature is

Magnetic field in a D.C. generator is produced by

The material for commutator brushes is generally

Eddy currents are induced in the pole shoes of a D.C. machine due to

Armature reaction of an unsaturated D.C. machine is

If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be

A D.C. welding generator has

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 generatorA and B will be

For a D.C. machines laboratory following type of D.C. supply will be suitable

The insulating material used between the commutator segments is normally

D.C. generators are connected to the busbars or disconnected from them only under the floating condition

The number of brushes in a commutator depends on

The function of pole shoes in the case of D.C. machine is

In D.C. generators, the brushes on commutator remain in contact with conductors which

Welding generator will have

The e.m.f. generated by a shunt wound D.C. generator isE. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be

In the case of lap winding resultant pitch is

In a D.C. generator the ripples in the direct e.m.f. generated are reduced by

Transformer Fundamentals and Operation

Transformer Technology and Design

Transformer: Resistance, Oil, Relays, Harmonics, and Core Properties

Transformers: Efficiency, Design, and Testing

Transformers: Voltage Regulation, Efficiency, and Protection

Transformer and D.C Motor

D.C Motors and Starters

D.C Motors and Speed Control

D.C Motors and Controls

D.C Motors and Generators

D.C Machine and Generator Laminations, Commutation, and Components

D.C Generator Operation and Construction

D.C Generators

Direct Current Generators and Parallel Operation

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