Question 1

The value of exciting or magnetizing current depends upon which of the following factors ?

Accepted Answer

A) Total m.m.f. required 
B) The number of turns in the exciting winding 
C) The way in which the winding is distributed 
D) All of the above 
A) Total m.m.f. required 
B) The number of turns in the exciting winding 
C) The way in which the winding is distributed 
D) All of the above D

Question 2

By which of the following methods motor rating for variable load drives can be determined ?

Accepted Answer

A) Method of average losses 
B) Equivalent current method 
C) Equivalent torque method 
D) All of the above. 
A) Method of average losses 
B) Equivalent current method 
C) Equivalent torque method 
D) All of the above. D

Question 3

electromagnets generally function as holding magnets.

Accepted Answer

A) Tractive 
B) Portative 
C) Either of the above 
D) None of the above 
A) Tractive 
B) Portative 
C) Either of the above 
D) None of the above B

Question 4

In direct cooled system using hydrogen both stator and rotor conductors are made

Accepted Answer

A) solid 
B) hollow 
C) perforated 
D) any ofthe above 
A) solid 
B) hollow 
C) perforated 
D) any ofthe above

Question 5

The time taken by the machine to attain 0.632 of its final steady temperature rise is called

Accepted Answer

A) heating time constant 
B) cooling time constant 
C) either (a) or (b) 
D) none of the above 
A) heating time constant 
B) cooling time constant 
C) either (a) or (b) 
D) none of the above

Question 6

The noise produced by a ______ cooled machine is less as the rotor moves in a medium of smaller density.

Accepted Answer

A) air 
B) hydrogen 
C) either (a) or (b) 
D) none of the above 
A) air 
B) hydrogen 
C) either (a) or (b) 
D) none of the above

Question 7

are used for construction of core of electromagnets.

Accepted Answer

A) Soft magnetic materials 
B) Hard magnetic materials 
C) Either (a) or (b) 
D) None of the above 
A) Soft magnetic materials 
B) Hard magnetic materials 
C) Either (a) or (b) 
D) None of the above

Question 8

Tractive magnets are operated from

Accepted Answer

A) a.c. supply 
B) d.c. supply 
C) either a.c. or d.c. supply 
D) none of the above 
A) a.c. supply 
B) d.c. supply 
C) either a.c. or d.c. supply 
D) none of the above

Question 9

By which of the following methods the temperature rise of windings and other parts may be determined ?

Accepted Answer

A) Thermometer method 
B) Resistance method 
C) Embedded temperature detector method 
D) Any of the above 
A) Thermometer method 
B) Resistance method 
C) Embedded temperature detector method 
D) Any of the above

Question 10

Which of the following is the commonly used type of electromagnets ?

Accepted Answer

A) Flat-faced armature type 
B) Horse shoe type 
C) Flat-faced plunger type 
D) All of the above 
A) Flat-faced armature type 
B) Horse shoe type 
C) Flat-faced plunger type 
D) All of the above

Question 11

The thermal conductivity of hydrogen is ______ times that of air

Accepted Answer

A) 2 
B) 3 
C) 5 
D) 7 
A) 2 
B) 3 
C) 5 
D) 7

Question 12

In self cooled motors the cooling time constant is about ______ than the heating time constant because cooling conditions are worse at standstill.

Accepted Answer

A) 2 to 3 times greater 
B) 3 to 4 times greater 
C) 4 to 5 times greater 
D) none of the above 
A) 2 to 3 times greater 
B) 3 to 4 times greater 
C) 4 to 5 times greater 
D) none of the above

Question 13

The density of hydrogen is _____ times the density of air.

Accepted Answer

A) 0.07 
B) 1.5 
C) 2.5 
D) 3.5 
A) 0.07 
B) 1.5 
C) 2.5 
D) 3.5

Question 14

With conventional hydrogen cooling it is possible to increase the rating of a single unit to

Accepted Answer

A) 50 MW 
B) 100 MW 
C) 200 MW 
D) none ofthe above 
A) 50 MW 
B) 100 MW 
C) 200 MW 
D) none ofthe above

Question 15

cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall

Accepted Answer

A) Direct 
B) Indirect 
C) Conventional 
D) Any ofthe above 
A) Direct 
B) Indirect 
C) Conventional 
D) Any ofthe above

Question 16

Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto

Accepted Answer

A) 10 MW 
B) 30 MW 
C) 60 MW 
D) 150 MW 
A) 10 MW 
B) 30 MW 
C) 60 MW 
D) 150 MW

Question 17

Which ofthe following is an advantage of hydrogen cooling ?

Accepted Answer

A) Increase in efficiency 
B) Increase in ratings 
C) Increase in life 
D) All ofthe above 
A) Increase in efficiency 
B) Increase in ratings 
C) Increase in life 
D) All ofthe above

Question 18

Hydrogen has a heat transfer co-efficient _____ times that of air

Accepted Answer

A) 1.5 
B) 2.5 
C) 3.5 
D) 4.5 
A) 1.5 
B) 2.5 
C) 3.5 
D) 4.5

Question 19

The resistivity of water should not be less than

Accepted Answer

A) 10 Q m 
B) 100 Q m 
C) 1000 Q m 
D) 2000 Q m 
A) 10 Q m 
B) 100 Q m 
C) 1000 Q m 
D) 2000 Q m

Question 20

Which of the following methods does not take into account the maximum temperature rise under variable load conditions ?

Accepted Answer

A) Equivalent power method 
B) Equivalent current method 
C) Method of average losses 
D) Equivalent torque method 
A) Equivalent power method 
B) Equivalent current method 
C) Method of average losses 
D) Equivalent torque method

The value of exciting or magnetizing current depends upon which of the following factors ?

By which of the following methods motor rating for variable load drives can be determined ?

electromagnets generally function as holding magnets.

In direct cooled system using hydrogen both stator and rotor conductors are made

The time taken by the machine to attain 0.632 of its final steady temperature rise is called

The noise produced by a ______ cooled machine is less as the rotor moves in a medium of smaller density.

are used for construction of core of electromagnets.

Tractive magnets are operated from

By which of the following methods the temperature rise of windings and other parts may be determined ?

Which of the following is the commonly used type of electromagnets ?

The thermal conductivity of hydrogen is ______ times that of air

In self cooled motors the cooling time constant is about ______ than the heating time constant because cooling conditions are worse at standstill.

The density of hydrogen is _____ times the density of air.

With conventional hydrogen cooling it is possible to increase the rating of a single unit to

cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall

Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto

Which ofthe following is an advantage of hydrogen cooling ?

Hydrogen has a heat transfer co-efficient _____ times that of air

The resistivity of water should not be less than

Which of the following methods does not take into account the maximum temperature rise under variable load conditions ?

Design Considerations and Materials for Electrical Machines

Transformer Design and Electromagnets

Design and Operation of DC Machines

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Exam 2: Cooling and Electromagnets for Machines

The value of exciting or magnetizing current depends upon which of the following factors ?

By which of the following methods motor rating for variable load drives can be determined ?

electromagnets generally function as holding magnets.

In direct cooled system using hydrogen both stator and rotor conductors are made

The time taken by the machine to attain 0.632 of its final steady temperature rise is called

The noise produced by a ______ cooled machine is less as the rotor moves in a medium of smaller density.

are used for construction of core of electromagnets.

Tractive magnets are operated from

By which of the following methods the temperature rise of windings and other parts may be determined ?

Which of the following is the commonly used type of electromagnets ?

The thermal conductivity of hydrogen is ______ times that of air

In self cooled motors the cooling time constant is about ______ than the heating time constant because cooling conditions are worse at standstill.

The density of hydrogen is _____ times the density of air.

With conventional hydrogen cooling it is possible to increase the rating of a single unit to

cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall

Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto

Which ofthe following is an advantage of hydrogen cooling ?

Hydrogen has a heat transfer co-efficient _____ times that of air

The resistivity of water should not be less than

Which of the following methods does not take into account the maximum temperature rise under variable load conditions ?

Design Considerations and Materials for Electrical Machines

Transformer Design and Electromagnets

Design and Operation of DC Machines

Filters