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

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
by

1 Answer

Answer :

(d) for 110 kV and above
by

Related questions

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

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

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

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

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

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

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

Last Answer : (c) high capacity transformers

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

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

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

Transmission voltage of ll kV is normally used for distances upto (a) 20—25 km (b) 40—50 km (c) 60—70 km (d) 80—100 km

Description : Transmission voltage of ll kV is normally used for distances upto (a) 20—25 km (b) 40—50 km (c) 60—70 km (d) 80—100 km

Last Answer : (a) 20—25 km

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

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

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 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

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

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

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 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

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

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

Description : 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

Last Answer : (c) at or near full load

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

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

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

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

Description : 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

Last Answer : (a) small size

Which of the following is the commonly used type of electromagnets ? (a) Flat-faced armature type (b) Horse shoe type (c) Flat-faced plunger type (d) All of the above

Description : Which of the following is the commonly used type of electromagnets ? (a) Flat-faced armature type (b) Horse shoe type (c) Flat-faced plunger type (d) All of the above

Last Answer : (d) All of the above

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

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

Description : 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 ... daily and seasonal voltage variations in accordance with variations of load (d) All of the above

Last Answer : (d) All of the above

The design of electromagnets is based upon which of the following fundamental equations ? (a) Force equation (b) Magnetic circuit equation (c) Heating equation (d) Voltage equation (e) All of the above

Description : The design of electromagnets is based upon which of the following fundamental equations ? (a) Force equation (b) Magnetic circuit equation (c) Heating equation (d) Voltage equation (e) All of the above

Last Answer : (e) All of the above

4 Helical coils can be used on A. Low voltage side of high kVA transformers B. High frequency transformers C. High voltage side of small capacity transformers D. High voltage side of high kVA rating transformers

Description : 4 Helical coils can be used on A. Low voltage side of high kVA transformers B. High frequency transformers C. High voltage side of small capacity transformers D. High voltage side of high kVA rating transformers

Last Answer : A) low voltage side of high KVA transformer

47 Cross over windings are used in A. Low voltage side of high kVA rating transformers B. Current transformers C. High voltage side of high kVA rating transformers D. High voltage side of low kVA rating transformers

Description : 47 Cross over windings are used in A. Low voltage side of high kVA rating transformers B. Current transformers C. High voltage side of high kVA rating transformers D. High voltage side of low kVA rating transformers

Last Answer : D. High voltage side of low kVA rating transformers

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

The operating voltage of extra high tension cables is upto (a) 6.6 kV (b) 11 kV (c) 33 kV (d) 66 kV (e) 132 kV

Description : The operating voltage of extra high tension cables is upto (a) 6.6 kV (b) 11 kV (c) 33 kV (d) 66 kV (e) 132 kV

Last Answer : (d) 66 kV

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 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

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

Last Answer : (a) Metal graphite brushes

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

______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

Description : ______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

Last Answer : (b) Cast steel

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

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

Last Answer : (c) high

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

Description : 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

Last Answer : (a) high

The speed of a multi-speed, squirrel-cage, induction motor operating in a fixed frequency system can be changed by _____________. A. reconnecting stator windings for different numbers of poles B. changing the RPM of the rotor flux C. changing the phase sequence of the applied voltage D. reconnecting the stator so that no poles have the same polarity

Description : The speed of a multi-speed, squirrel-cage, induction motor operating in a fixed frequency system can be changed by _____________. A. reconnecting stator windings for different numbers of poles B. ... sequence of the applied voltage D. reconnecting the stator so that no poles have the same polarity

Last Answer : Answer: A

For transmission of power over a distance of 500 km, the transmission voltage should be in the range (a) 150 to 220 kV (b) 100 to 120 kV (c) 60 to 100 kV (d) 20 to 50 kV

Description : For transmission of power over a distance of 500 km, the transmission voltage should be in the range (a) 150 to 220 kV (b) 100 to 120 kV (c) 60 to 100 kV (d) 20 to 50 kV

Last Answer : (a) 150 to 220 kV

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

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