Question 1

Power transformers have rating

Accepted Answer

A) equal to 50 kVA 
B) equal to 100 kVA 
C) above 200 kVA 
D) none of the above 
A) equal to 50 kVA 
B) equal to 100 kVA 
C) above 200 kVA 
D) none of the above C

Question 2

The voltage control in electric supply networks in required on account of which of the following reasons ?

Accepted Answer

A) Adjustment of voltage at consumers premises within statutory limits 
B) Control of active and reactive power 
C) Adjustment of short period daily and seasonal voltage variations in accordance with variations of load 
D) All of the above 
A) Adjustment of voltage at consumers premises within statutory limits 
B) Control of active and reactive power 
C) Adjustment of short period daily and seasonal voltage variations in accordance with variations of load 
D) All of the above D

Question 3

In transformers using hot rolled steel, the cross-section of the yoke is made about _____ greater than that of the core

Accepted Answer

A) 5 percent 
B) 10 percent 
C) 15 percent 
D) 30 percent 
A) 5 percent 
B) 10 percent 
C) 15 percent 
D) 30 percent C

Question 4

The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?

Accepted Answer

A) Corrugations 
B) Fins 
C) Tubes 
D) All of the above 
A) Corrugations 
B) Fins 
C) Tubes 
D) All of the above

Question 5

When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of

Accepted Answer

A) short pitch 
B) full pitch 
C) either of the above 
D) none of the above 
A) short pitch 
B) full pitch 
C) either of the above 
D) none of the above

Question 6

Yokes with rectangular cross-section are used for

Accepted Answer

A) small capacity transformers 
B) medium capacity transformers 
C) large capacity transformers 
D) any of the above 
A) small capacity transformers 
B) medium capacity transformers 
C) large capacity transformers 
D) any of the above

Question 7

Dummy coil should not be used in

Accepted Answer

A) small machines 
B) large machines 
C) either (a) or (b) 
D) none of the above 
A) small machines 
B) large machines 
C) either (a) or (b) 
D) none of the above

Question 8

The design of electromagnets is based upon which of the following fundamental equations ?

Accepted Answer

A) Force equation 
B) Magnetic circuit equation 
C) Heating equation 
D) All of the above 
A) Force equation 
B) Magnetic circuit equation 
C) Heating equation 
D) All of the above

Question 9

For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used ?

Accepted Answer

A) 1.0 to 1.2 A/mm2 
B) 1.5 to 2.0 A/mm2 
C) 2.2 to 3.2 A/mm2 
D) 3.2 to 4.2 A/mm2 
A) 1.0 to 1.2 A/mm2 
B) 1.5 to 2.0 A/mm2 
C) 2.2 to 3.2 A/mm2 
D) 3.2 to 4.2 A/mm2

Question 10

A current density of _____ is ilsed for large power transformers with forced circulation of oil or with water cooling coils

Accepted Answer

A) 1.5 to 2.5 A/mm2 
B) 3.5 to 4.5 A/mm2 
C) 4.0 to 5.0 A/mm2 
D) 5.4 to 6.2 A/mm2 
A) 1.5 to 2.5 A/mm2 
B) 3.5 to 4.5 A/mm2 
C) 4.0 to 5.0 A/mm2 
D) 5.4 to 6.2 A/mm2

Question 11

The forced oil and air circulation method is usual one for transformers of capacities

Accepted Answer

A) upto 5 MVA 
B) upto 10 MVA 
C) upto 20 MVA 
D) 30 MVA upwards 
A) upto 5 MVA 
B) upto 10 MVA 
C) upto 20 MVA 
D) 30 MVA upwards

Question 12

Transformers with a capacity of upto _____ have a cooling radiator system with natural cooling

Accepted Answer

A) 2 MVA 
B) 5 MVA 
C) 7.5 MVA 
D) 10 MVA 
A) 2 MVA 
B) 5 MVA 
C) 7.5 MVA 
D) 10 MVA

Question 13

Power transformers should be designed to have maximum efficiency

Accepted Answer

A) at one-fourth load 
B) at one-half load 
C) at or near full load 
D) any of the above 
A) at one-fourth load 
B) at one-half load 
C) at or near full load 
D) any of the above

Question 14

Cylindrical windings using circular conductors, employed in transformers, are

Accepted Answer

A) single layered 
B) double layered 
C) multi-layered 
D) none of the above 
A) single layered 
B) double layered 
C) multi-layered 
D) none of the above

Question 15

The distance between the starts of two consecutive coils measured in terms of coil sides is called

Accepted Answer

A) front pitch 
B) winding pitch 
C) commutator pitch 
D) back pitch 
A) front pitch 
B) winding pitch 
C) commutator pitch 
D) back pitch

Question 16

The winding where dummy coils are used is sometimes called

Accepted Answer

A) duplex winding 
B) triplex winding 
C) forced winding 
D) none of the above 
A) duplex winding 
B) triplex winding 
C) forced winding 
D) none of the above

Question 17

Disc windings are primarily used in

Accepted Answer

A) short capacity transformers 
B) medium capacity transformers 
C) high capacity transformers 
D) any of the above 
A) short capacity transformers 
B) medium capacity transformers 
C) high capacity transformers 
D) any of the above

Question 18

Helical windings are used in

Accepted Answer

A) distribution transformers 
B) power transformers 
C) shell type transformers 
D) none of the above 
A) distribution transformers 
B) power transformers 
C) shell type transformers 
D) none of the above

Question 19

The flash point of transformer oil should be higher than

Accepted Answer

A) 40°C 
B) 60°C 
C) 80°C 
D) 104°C 
A) 40°C 
B) 60°C 
C) 80°C 
D) 104°C

Question 20

The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are

Accepted Answer

A) 0.5 to 0.8 Wb/m2 
B) 0.8 to 1.0 Wb/m2 
C) 1.1 to 1.35 Wb/m2 
D) 1.4 to 1.8 Wb/m2 
A) 0.5 to 0.8 Wb/m2 
B) 0.8 to 1.0 Wb/m2 
C) 1.1 to 1.35 Wb/m2 
D) 1.4 to 1.8 Wb/m2

Power transformers have rating

The voltage control in electric supply networks in required on account of which of the following reasons ?

In transformers using hot rolled steel, the cross-section of the yoke is made about _____ greater than that of the core

The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?

When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of

Yokes with rectangular cross-section are used for

Dummy coil should not be used in

The design of electromagnets is based upon which of the following fundamental equations ?

For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used ?

A current density of _____ is ilsed for large power transformers with forced circulation of oil or with water cooling coils

The forced oil and air circulation method is usual one for transformers of capacities

Transformers with a capacity of upto _____ have a cooling radiator system with natural cooling

Power transformers should be designed to have maximum efficiency

Cylindrical windings using circular conductors, employed in transformers, are

The distance between the starts of two consecutive coils measured in terms of coil sides is called

The winding where dummy coils are used is sometimes called

Disc windings are primarily used in

Helical windings are used in

The flash point of transformer oil should be higher than

The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are

Design Considerations and Materials for Electrical Machines

Cooling and Electromagnets for Machines

Design and Operation of DC Machines

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Exam 3: Transformer Design and Electromagnets

Power transformers have rating

The voltage control in electric supply networks in required on account of which of the following reasons ?

In transformers using hot rolled steel, the cross-section of the yoke is made about _____ greater than that of the core

The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?

When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of

Yokes with rectangular cross-section are used for

Dummy coil should not be used in

The design of electromagnets is based upon which of the following fundamental equations ?

For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used ?

A current density of _____ is ilsed for large power transformers with forced circulation of oil or with water cooling coils

The forced oil and air circulation method is usual one for transformers of capacities

Transformers with a capacity of upto _____ have a cooling radiator system with natural cooling

Power transformers should be designed to have maximum efficiency

Cylindrical windings using circular conductors, employed in transformers, are

The distance between the starts of two consecutive coils measured in terms of coil sides is called

The winding where dummy coils are used is sometimes called

Disc windings are primarily used in

Helical windings are used in

The flash point of transformer oil should be higher than

The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are

Design Considerations and Materials for Electrical Machines

Cooling and Electromagnets for Machines

Design and Operation of DC Machines

Filters