Disc windings are primarily used in (a) short capacity transformers (b) medium capacity transformers (c) high capacity transformers (d) any of the above

Disc windings are primarily used in
(a) short capacity transformers
(b) medium capacity transformers
(c) high capacity transformers
(d) any of the above
by

1 Answer

Answer :

(c) high capacity transformers
by

Related questions

Multi-layer helical windings are commonly used in the transformers as high voltage windings (a) upto 20 kV (b) upto 50 kV (c) upto 80 kV (d) for 110 kV and above

Description : Multi-layer helical windings are commonly used in the transformers as high voltage windings (a) upto 20 kV (b) upto 50 kV (c) upto 80 kV (d) for 110 kV and above

Last Answer : (d) for 110 kV and above

Yokes with rectangular cross-section are used for (a) small capacity transformers (b) medium capacity transformers (c) large capacity transformers (d) any of the above

Description : Yokes with rectangular cross-section are used for (a) small capacity transformers (b) medium capacity transformers (c) large capacity transformers (d) any of the above

Last Answer : (a) small capacity transformers

Helical windings are used in (a) distribution transformers (b) power transformers (c) shell type transformers (d) none of the above

Description : Helical windings are used in (a) distribution transformers (b) power transformers (c) shell type transformers (d) none of the above

Last Answer : (b) power transformers

Cylindrical windings using circular conductors, employed in transformers, are (a) single layered (b) double layered (c) multi-layered (d) none of the above

Description : Cylindrical windings using circular conductors, employed in transformers, are (a) single layered (b) double layered (c) multi-layered (d) none of the above

Last Answer : (c) multi-layered

The surge phenomenon is particularly important in case of (a) low voltage transformers (b) medium voltage transformers (c) high voltage transformers (d) any of the above

Description : The surge phenomenon is particularly important in case of (a) low voltage transformers (b) medium voltage transformers (c) high voltage transformers (d) any of the above

Last Answer : (c) high voltage transformers

Aluminium when adopted as a conductor material in ______ transformers, decreases the overall cost of the transformer (a) small size (b) medium size (c) large size (d) any of the above size

Description : Aluminium when adopted as a conductor material in ______ transformers, decreases the overall cost of the transformer (a) small size (b) medium size (c) large size (d) any of the above size

Last Answer : (a) small size

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 practical formula for determining the thickness of insulation between low voltage and high voltage windings is (a) 1 + 0.2 kVmm (6) 2 + 0.5 kVmm (c) 4 + 0.7 kV mm (d) 5 + 0.9 kV mm

Description : A practical formula for determining the thickness of insulation between low voltage and high voltage windings is (a) 1 + 0.2 kVmm (6) 2 + 0.5 kVmm (c) 4 + 0.7 kV mm (d) 5 + 0.9 kV mm

Last Answer : (d) 5 + 0.9 kV mm

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

The weight of copper of both armature and field windings decreases with _____ in number of poles. (a) increase (b) decrease (c) either of the above (d) none of the above

Description : The weight of copper of both armature and field windings decreases with _____ in number of poles. (a) increase (b) decrease (c) either of the above (d) none of the above

Last Answer : (a) increase

The cylindrical windings using circular conductors are used for current rating of (a) upto 20 A (b) upto 40 A (c) upto 60 A (d) upto 80 A

Description : The cylindrical windings using circular conductors are used for current rating of (a) upto 20 A (b) upto 40 A (c) upto 60 A (d) upto 80 A

Last Answer : (d) upto 80 A

The insulation between windings and grounded core and the insulation between the windings of the same phase is called (a) minor insulation (b) major insulation (c) either of the above (d) none of the above

Description : The insulation between windings and grounded core and the insulation between the windings of the same phase is called (a) minor insulation (b) major insulation (c) either of the above (d) none of the above

Last Answer : (b) major insulation

D.C. windings are (a) sometimes 2-layer type (b) never 2-layer type (c) always 2-layer type (d) none of the above

Description : D.C. windings are (a) sometimes 2-layer type (b) never 2-layer type (c) always 2-layer type (d) none of the above

Last Answer : (c) always 2-layer type

are always double layer type. (a) Closed windings (b) Open windings (c) Either of the above (d) None of the above

Description : are always double layer type. (a) Closed windings (b) Open windings (c) Either of the above (d) None of the above

Last Answer : (a) Closed windings

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

is universally used for windings of electrical machines because it is easily workable without any possibility of fracture. (a) Silver (b) Steel (c) Aluminium (d) Copper

Description : is universally used for windings of electrical machines because it is easily workable without any possibility of fracture. (a) Silver (b) Steel (c) Aluminium (d) Copper

Last Answer : (d) Copper

The high voltage winding is usually which of the following type ? (a) Cylindrical winding with circular conductors (b) Cross-over winding with either circular or small rectangular conductors (c) Continuous disc type winding with rectangular conductors (d) All of the above types

Description : The high voltage winding is usually which of the following type ? (a) Cylindrical winding with circular conductors (b) Cross-over winding with either circular or small rectangular conductors (c) Continuous disc type winding with rectangular conductors (d) All of the above types

Last Answer : (d) All of the above types

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

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

For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used? (a) 1.0 Wb/m2 (b) 1.1 Wb/m2 (c) 1.3 Wb/m2 (d) 1.6 Wb/m2 (e) None of the above

Description : For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used? (a) 1.0 Wb/m2 (b) 1.1 Wb/m2 (c) 1.3 Wb/m2 (d) 1.6 Wb/m2 (e) None of the above

Last Answer : (d) 1.6 Wb/m2

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

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

Last Answer : (c) 1.1 to 1.35 Wb/m2

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 heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ? (a) Corrugations (b) Fins (c) Tubes (d) Radiator tanks (e) All of the above

Description : The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ? (a) Corrugations (b) Fins (c) Tubes (d) Radiator tanks (e) All of the above

Last Answer : (e) All of the above

In transformers using hot rolled steel, the cross-section of the yoke is made about _____ greater than that of the core (a) 5 percent (b) 10 percent (c) 15 percent (d) 30 percent (e) none of the above

Description : In transformers using hot rolled steel, the cross-section of the yoke is made about _____ greater than that of the core (a) 5 percent (b) 10 percent (c) 15 percent (d) 30 percent (e) none of the above

Last Answer : (c) 15 percent

Power transformers should be designed to have maximum efficiency (a) at one-fourth load (b) at one-half load (c) at or near full load (d) any of the above

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Last Answer : (c) at or near full load

Power transformers have rating (a) equal to 50 kVA (6) equal to 100 kVA (c) above 200 kVA (d) none of the above

Description : Power transformers have rating (a) equal to 50 kVA (6) equal to 100 kVA (c) above 200 kVA (d) none of the above

Last Answer : (c) above 200 kVA

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

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Last Answer : (c) induction motor

The design of mechanical parts is particularly important in case of _____ speed machines. (a) low (b) medium (c) high (d) any of the above

Description : The design of mechanical parts is particularly important in case of _____ speed machines. (a) low (b) medium (c) high (d) any of the above

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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

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Last Answer : (b) high power factor

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

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

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Commercial available medium size machines have a speed range of ______ . (a) 200 to 400 r.p.m. (b) 600 to 1000 r.p.m. (c) 1000 to 1500 r.p.m. (d) 2000 to 2500 r.p.m.

Description : Commercial available medium size machines have a speed range of ______ . (a) 200 to 400 r.p.m. (b) 600 to 1000 r.p.m. (c) 1000 to 1500 r.p.m. (d) 2000 to 2500 r.p.m.

Last Answer : (d) 2000 to 2500 r.p.m.

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

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Electrical machines having a power output upto about 750 W may be called_______machines. (a) small size (b) medium size (c) large size (d) any of the above

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In ______ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft. (a) small (b) medium (c) large (d) any of the above.

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

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Last Answer : (d) All of the above

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

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Last Answer : (b) full pitch

Which of the following brushes can be used for high values of current density ? (a) Metal graphite brushes (b) Hard carbon brushes (c) Electro-graphitic brushes (d) Natural graphite brushes

Description : Which of the following brushes can be used for high values of current density ? (a) Metal graphite brushes (b) Hard carbon brushes (c) Electro-graphitic brushes (d) Natural graphite brushes

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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

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______is extensively used for those portions of magnetic circuit which carry steady flux and need superior mechanical properties ? (a) Grey cast-iron (b) Cast steel (c) High carbon steel (d) Stainless steel

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The efficiency of a machine should be as ______ as possible to reduce the operating cost. (a) high (b) low (c) either of the above (d) none of the above

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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

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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

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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

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Last Answer : (a) quiet

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

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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

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

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

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Last Answer : (c) better ventilation

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

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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