Which ofthe following methods is used for air cooling of turbo-alternators ? (a) One sided axial ventilation (b) Two sided axial ventilation (c) Multiple inlet system (d) All ofthe above

Which ofthe following methods is used for air cooling of turbo-alternators ?
(a) One sided axial ventilation
(b) Two sided axial ventilation
(c) Multiple inlet system
(d) All ofthe above
by

1 Answer

Answer :

(d) All ofthe above
by

Related questions

Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto (a) 10 MW (b) 30 MW (c) 60 MW (d) 150 MW

Description : Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto (a) 10 MW (b) 30 MW (c) 60 MW (d) 150 MW

Last Answer : (c) 60 MW

cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall (a) Direct (b) Indirect (c) Conventional (d) Any ofthe above

Description : cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall (a) Direct (b) Indirect (c) Conventional (d) Any ofthe above

Last Answer : (a) Direct

With conventional hydrogen cooling it is possible to increase the rating of a single unit to (a) 50 MW (b) 100 MW (c) 200 MW (d) none ofthe above

Description : With conventional hydrogen cooling it is possible to increase the rating of a single unit to (a) 50 MW (b) 100 MW (c) 200 MW (d) none ofthe above

Last Answer : (c) 200 MW

Which ofthe following is an advantage of hydrogen cooling ? (a) Increase in efficiency (b) Increase in ratings (c) Increase in life (d) Smaller size of coolers (e) All ofthe above

Description : Which ofthe following is an advantage of hydrogen cooling ? (a) Increase in efficiency (b) Increase in ratings (c) Increase in life (d) Smaller size of coolers (e) All ofthe above

Last Answer : (e) All ofthe above

The mcrease in heat dissipation by air blasts is due to increase in (a) conduction (b) convection (e) radiation (d) any ofthe above

Description : The mcrease in heat dissipation by air blasts is due to increase in (a) conduction (b) convection (e) radiation (d) any ofthe above

Last Answer : (b) convection

D.C. machines designed with a large value of air gap length have (a) worst, ventilation (b) poor ventilation (c) better ventilation (d) none of the above

Description : D.C. machines designed with a large value of air gap length have (a) worst, ventilation (b) poor ventilation (c) better ventilation (d) none of the above

Last Answer : (c) better ventilation

In direct cooled system using hydrogen both stator and rotor conductors are made (a) solid (b) hollow (c) perforated (d) any ofthe above

Description : In direct cooled system using hydrogen both stator and rotor conductors are made (a) solid (b) hollow (c) perforated (d) any ofthe above

Last Answer : (b) hollow

On which of the following variables heat convected depends ? (a) Power density (b) Temperature difference between heated surface and coolant (c) Thermal resistivity, density, specific heat (d) Gravitational constant (e) All ofthe above

Description : On which of the following variables heat convected depends ? (a) Power density (b) Temperature difference between heated surface and coolant (c) Thermal resistivity, density, specific heat (d) Gravitational constant (e) All ofthe above

Last Answer : (e) All ofthe above

The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc. (a) conduction (b) convection (c) radiation (d) any ofthe above

Description : The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc. (a) conduction (b) convection (c) radiation (d) any ofthe above

Last Answer : (c) radiation

The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ? (a) Conduction (b) Convection (c) Radiation (d) All ofthe above

Description : The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ? (a) Conduction (b) Convection (c) Radiation (d) All ofthe above

Last Answer : (d) All ofthe above

Hot rolled sheets have ______ value of permeability (a) zero (b) low (c) high (d) none ofthe above

Description : Hot rolled sheets have ______ value of permeability (a) zero (b) low (c) high (d) none ofthe above

Last Answer : (b) low

Which ofthe following materials is used in the manufacture of resistance grids to be used in the starters of large motors ? (a) Copper (b) Aluminium (c) Steel (d) Cast-iron

Description : Which ofthe following materials is used in the manufacture of resistance grids to be used in the starters of large motors ? (a) Copper (b) Aluminium (c) Steel (d) Cast-iron

Last Answer : (d) Cast-iron

The change in flux linkages can be caused in which ofthe following ways ? (a) The flux is constant with respect to time and is stationary and the coil moves through it (b) The coil is stationary with respect to flux and the flux varies in magnitude with respect to time (c) Both the changes mentioned above occure together, i.e., the coil moves through a time varying field (d) All ofthe above

Description : The change in flux linkages can be caused in which ofthe following ways ? (a) The flux is constant with respect to time and is stationary and the coil moves through it (b) The coil is stationary with ... above occure together, i.e., the coil moves through a time varying field (d) All ofthe above

Last Answer : (d) All ofthe above

The action of electromagnetic machines can be related to which ofthe following basic principles ? (a) Induction (b) Interaction (c) Alignment (d) All of the above

Description : The action of electromagnetic machines can be related to which ofthe following basic principles ? (a) Induction (b) Interaction (c) Alignment (d) All of the above

Last Answer : (d) All of the above

Electrical machines having power outputs ranging from a few kW upto approximately 250 kW may be classified as (a) small size machines (b) medium size machines (c) large size machines (d) any ofthe above

Description : Electrical machines having power outputs ranging from a few kW upto approximately 250 kW may be classified as (a) small size machines (b) medium size machines (c) large size machines (d) any ofthe above

Last Answer : (b) medium size machines

Which of the following methods may be adopted to reduce the effects of armature reaction ? (a) Increase in length of air gap at pole tips (b) Increasing reluctance of pole tips (c) Compensating windings (d) Interpoles (e) All of the above

Description : Which of the following methods may be adopted to reduce the effects of armature reaction ? (a) Increase in length of air gap at pole tips (b) Increasing reluctance of pole tips (c) Compensating windings (d) Interpoles (e) All of the above

Last Answer : (e) All of the above

Transformers with a capacity of upto _____ have a cooling radiator system with natural cooling (a) 2 MVA (b) 5 MVA (c) 7.5 MVA (d) 10 MVA

Description : Transformers with a capacity of upto _____ have a cooling radiator system with natural cooling (a) 2 MVA (b) 5 MVA (c) 7.5 MVA (d) 10 MVA

Last Answer : (d) 10 MVA

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

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

Last Answer : (d) 5.4 to 6.2 A/mm2

In self cooled motors the cooling time constant is about ______ than the heating time constant because cooling conditions are worse at standstill. (a) 2 to 3 times greater (b) 3 to 4 times greater (c) 4 to 5 times greater (d) none of the above

Description : In self cooled motors the cooling time constant is about ______ than the heating time constant because cooling conditions are worse at standstill. (a) 2 to 3 times greater (b) 3 to 4 times greater (c) 4 to 5 times greater (d) none of the above

Last Answer : (a) 2 to 3 times greater

The time taken by the machine to attain 0.632 of its final steady temperature rise is called (a) heating time constant (b) cooling time constant (c) either (a) or (b) (d) none of the above

Description : The time taken by the machine to attain 0.632 of its final steady temperature rise is called (a) heating time constant (b) cooling time constant (c) either (a) or (b) (d) none of the above

Last Answer : (a) heating time constant

Direct water cooling of rotor winding presents (a) no mechanical difficulties (b) lesser mechanical difficulties (c) greater mechanical difficulties (d) none of the above

Description : Direct water cooling of rotor winding presents (a) no mechanical difficulties (b) lesser mechanical difficulties (c) greater mechanical difficulties (d) none of the above

Last Answer : (c) greater mechanical difficulties

With direct water cooling it is possible to have ratings of about (a) 200 MW (b) 300 MW (c) 400 MW (d) 600 MW

Description : With direct water cooling it is possible to have ratings of about (a) 200 MW (b) 300 MW (c) 400 MW (d) 600 MW

Last Answer : (d) 600 MW

Machines cooled by direct cooling method may be called (a) "supercharged" (b) "inner cooled" (c) "conductor cooled" (d) any of the above

Description : Machines cooled by direct cooling method may be called (a) "supercharged" (b) "inner cooled" (c) "conductor cooled" (d) any of the above

Last Answer : (d) any of the above

By which of the following methods the temperature rise of windings and other parts may be determined ? (a) Thermometer method (6) Resistance method (c) Embedded temperature detector method (d) Any of the above

Description : By which of the following methods the temperature rise of windings and other parts may be determined ? (a) Thermometer method (6) Resistance method (c) Embedded temperature detector method (d) Any of the above

Last Answer : (d) Any of the above

Which of the following methods is most accurate ? (a) Equivalent current method (b) Equivalent power method (c) Equivalent torque method (d) Method of average losses

Description : Which of the following methods is most accurate ? (a) Equivalent current method (b) Equivalent power method (c) Equivalent torque method (d) Method of average losses

Last Answer : (a) Equivalent current method

Which of the following methods does not take into account the maximum temperature rise under variable load conditions ? (a) Equivalent power method (b) Equivalent current method (c) Method of average losses (d) Equivalent torque method

Description : Which of the following methods does not take into account the maximum temperature rise under variable load conditions ? (a) Equivalent power method (b) Equivalent current method (c) Method of average losses (d) Equivalent torque method

Last Answer : (c) Method of average losses

By which of the following methods motor rating for variable load drives can be determined ? (a) Method of average losses (b) Equivalent current method (c) Equivalent torque method (d) Equivalent power method (e) All of the above.

Description : By which of the following methods motor rating for variable load drives can be determined ? (a) Method of average losses (b) Equivalent current method (c) Equivalent torque method (d) Equivalent power method (e) All of the above.

Last Answer : (e) All of the above.

The operation of a D.C. machine with large air gap lengths is comparatively (a) quiet (b) noisy (c) either of the above (d) none of the above

Description : The operation of a D.C. machine with large air gap lengths is comparatively (a) quiet (b) noisy (c) either of the above (d) none of the above

Last Answer : (a) quiet

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

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

Last Answer : (c) 2.2 to 3.2 A/mm2

The forced oil and air circulation method is usual one for transformers of capacities (a) upto 5 MVA (b) upto 10 MVA (c) upto 20 MVA (d) 30 MVA upwards

Description : The forced oil and air circulation method is usual one for transformers of capacities (a) upto 5 MVA (b) upto 10 MVA (c) upto 20 MVA (d) 30 MVA upwards

Last Answer : (d) 30 MVA upwards

The slot leakage can be calculated by making which of the following assumptions ? (a) The current in the slot conductors is uniformly distributed over their cross-section (b) The leakage path is straight across the slot and around the iron at the bottom (c) The permanence of air paths is only considered. The reluctance of iron paths is assumed as zero (d) All of the above

Description : The slot leakage can be calculated by making which of the following assumptions ? (a) The current in the slot conductors is uniformly distributed over their cross-section (b) The leakage path is straight ... is only considered. The reluctance of iron paths is assumed as zero (d) All of the above

Last Answer : (d) All of the above

The noise produced by a ______ cooled machine is less as the rotor moves in a medium of smaller density. (a) air (b) hydrogen (c) either (a) or (b) (d) none of the above

Description : The noise produced by a ______ cooled machine is less as the rotor moves in a medium of smaller density. (a) air (b) hydrogen (c) either (a) or (b) (d) none of the above

Last Answer : (b) hydrogen

The thermal conductivity of hydrogen is ______ times that of air (a) 2 (b) 3 (c) 5 (d) 7

Description : The thermal conductivity of hydrogen is ______ times that of air (a) 2 (b) 3 (c) 5 (d) 7

Last Answer : (d) 7

Hydrogen has a heat transfer co-efficient _____ times that of air (a) 1.5 (b) 2.5 (c) 3.5 (d) 4.5

Description : Hydrogen has a heat transfer co-efficient _____ times that of air (a) 1.5 (b) 2.5 (c) 3.5 (d) 4.5

Last Answer : (a) 1.5

The density of hydrogen is _____ times the density of air. (a) 0.07 (b) 1.5 (c) 2.5 (d) 3.5

Description : The density of hydrogen is _____ times the density of air. (a) 0.07 (b) 1.5 (c) 2.5 (d) 3.5

Last Answer : (a) 0.07

The length cf air gap to be provided in ______ is primarily determined by power factor consideration. (a) d.c. series motor . (b) d.c. shunt motor (c) induction motor (d) synchronous motor

Description : The length cf air gap to be provided in ______ is primarily determined by power factor consideration. (a) d.c. series motor . (b) d.c. shunt motor (c) induction motor (d) synchronous motor

Last Answer : (c) induction motor

In induction motors, the length of air gap in kept as small as mechanically possible is order to have (a) low power factor (b) high power factor (c) high over load capacity (d) any of the above

Description : In induction motors, the length of air gap in kept as small as mechanically possible is order to have (a) low power factor (b) high power factor (c) high over load capacity (d) any of the above

Last Answer : (b) high power factor

What Is Meant By Turbo Alternators?

Description : What Is Meant By Turbo Alternators?

Last Answer : Turbo alternators are high speed alternators. Because of high speed of rotation, the rotor diameter is reduced and the axial length is increased. Two or four poles are generally used and steam turbines are used as prime movers.

Which rotor is use for high speed in turbo alternators?

Description : Which rotor is use for high speed in turbo alternators?

Last Answer : Non-salient pole rotor is used for high speed in turbo alternators.

What is a narrow steep sided inlet of the sea carved by a glacier?

Description : What is a narrow steep sided inlet of the sea carved by a glacier?

Last Answer : What is the answer ?

Consider the following statements : 1. Salient pole alternators have small diameters and large axial lengths....

Description : Consider the following statements :  1. Salient pole alternators have small diameters and large axial lengths.  2. Cylindrical rotor alternators have a distributed winding.  3. Cylindrical rotor alternators are wound for large number ... 3 only (b) 2 and 4 only (c) 1 and 4 only (d) 2 and 3 only

Last Answer : Consider the following statements :  1. Salient pole alternators have small diameters and large axial lengths.  2. Cylindrical rotor alternators have a distributed winding.  3. Cylindrical rotor alternators are wound for ... 3 only (b) 2 and 4 only (c) 1 and 4 only (d) 2 and 3 only

The distance between the starts of two consecutive coils measured in terms of coil sides is called (a) front pitch (b) winding pitch (c) commutator pitch (d) back pitch

Description : The distance between the starts of two consecutive coils measured in terms of coil sides is called (a) front pitch (b) winding pitch (c) commutator pitch (d) back pitch

Last Answer : (b) winding pitch

When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of (a) short pitch (b) full pitch (c) either of the above (d) none of the above

Description : When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of (a) short pitch (b) full pitch (c) either of the above (d) none of the above

Last Answer : (b) full pitch

In D.C. machines the number of slots per pole usually lies (a) between 2 to 4 (b) between 6 to 8 (c) between 9 to 16 (d) between 20 to 30

Description : In D.C. machines the number of slots per pole usually lies (a) between 2 to 4 (b) between 6 to 8 (c) between 9 to 16 (d) between 20 to 30

Last Answer : (c) between 9 to 16

In D.C. machines the usual limit of slot pitch is (a) between 5 to 10 mm (b) between 10 to 15 mm (c) between 15 to 20 mm (d) between 25 to 35 mm

Description : In D.C. machines the usual limit of slot pitch is (a) between 5 to 10 mm (b) between 10 to 15 mm (c) between 15 to 20 mm (d) between 25 to 35 mm

Last Answer : (d) between 25 to 35 mm

In D.C. machines, the ____ in field mmf results in increase in size and cost of machines. (a) increase (b) decrease (c) either of the above (d) none of the above

Description : In D.C. machines, the ____ in field mmf results in increase in size and cost of machines. (a) increase (b) decrease (c) either of the above (d) none of the above

Last Answer : (a) increase

In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made (a) equal to that of armature mmf (b) less in comparison with the arma¬ture mmf (c) large in comparison with the arma-ture mmf (d) none of the above

Description : In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made (a) equal to that of armature mmf (b) less in comparison with the arma¬ture mmf (c) large in comparison with the arma-ture mmf (d) none of the above

Last Answer : (c) large in comparison with the arma-ture mmf

In D.C. machines the width of the duct is usually (a) 4 mm (b) 6 mm (c) 8 mm (d) 10 mm

Description : In D.C. machines the width of the duct is usually (a) 4 mm (b) 6 mm (c) 8 mm (d) 10 mm

Last Answer : (d) 10 mm

In a D.C. machine, the value of peripheral speed should not, normally, exceed (a) 10 m/s (b) 20 m/s (c) 30 m/s (d) 40 m/s

Description : In a D.C. machine, the value of peripheral speed should not, normally, exceed (a) 10 m/s (b) 20 m/s (c) 30 m/s (d) 40 m/s

Last Answer : (c) 30 m/s

In a D.C. machine the current per brush arm should not be more than (a) 100 A (6) 200 A (e) 300 A (d) 400 A

Description : In a D.C. machine the current per brush arm should not be more than (a) 100 A (6) 200 A (e) 300 A (d) 400 A

Last Answer : (d) 400 A