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

1 Answer

Answer :

(d) Copper

Related questions

Description : is usually used for brush rockers (a) Mild steel (b) Copper (c) Aluminium (d) Cast-iron

Last Answer : (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

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

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

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

Description : ________ has a lowrelative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable. (a) Cast steel (b) Aluminium (c) Soft steel (d) Cast iron

Last Answer : (d) Cast iron

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

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

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

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

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

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

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

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

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

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

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

Last Answer : Copper, even though costly, finds use in the windings of electrical machines because copper points offer low contact resistance , copper can be easily soldered and welded, copper windings are less bulky and the machines become compact.

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

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

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

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

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

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

Description : Dummy coil should not be used in (a) small machines (b) large machines (c) either (a) or (b) (d) none of the above

Last Answer : (b) large machines

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

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

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

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.

Description : 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.

Last Answer : (c) large

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

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

Description : Which of the following is the basic consideration in the design of insulation ? (a) Electrical considerations (b) Mechanical considerations (c) Thermal considerations (d) All of the above

Last Answer : (d) All of the 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

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

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

Description : The cold rolled grain oriented steel has ______ permeability in the direction of the grain orientation. (a) minimum (b) maximum (c) nil (d) none of the above

Last Answer : (b) maximum

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

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

Description : Pick out the wrong statement. (A) Bronze is an alloy of copper & tin (B) Brass is an alloy of copper & zinc (C) The alloy named 'German silver' does not contain any silver (D) The ability of a material to fracture without appreciable deformation is called its ductility

Last Answer : (D) The ability of a material to fracture without appreciable deformation is called its ductility

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

Description : The metal whose electrical conductivity is more, is – (1) copper (2) aluminium (3) silver (4) lead

Last Answer : (3) silver Explanation: Copper ; 9% less conductive than silver: aluminium is 1 0% less conductive than copper; while steel is the least conductive among the given options. The most electrically conductive metal is silver.

Description : The metal whose electrical conductivity is more, is (1) copper (2) aluminium (3) silver (4) lead

Last Answer : silver

Description : When repairing a fracture of a lower complete denture, which statement is correct: A. Self curing will distort the denture B. Cold curing will not be strong enough because of small area of attachment C. There is a possibility of occlusal disharmony

Last Answer : C. There is a possibility of occlusal disharmony

Description : Which of the following materials has the poorest electrical conductivity? (A) Carbon (B) Aluminium (C) Silver (D) Stainless steel

Last Answer : (A) Carbon

Description : Which of the following is arranged in order of decreasing conductivity? (1) Copper, Aluminium, Steel, Silver (2) Aluminium, Silver, Copper, Steel (3) Copper, Silver, Aluminium, Steel (4) Silver, Copper, Aluminium, Steel

Last Answer : (4) Silver, Copper, Aluminium, Steel Explanation: Copper ; 9% less conductive than silver; aluminium is 10% less conductive than copper; while steel is the least conductive among the given options. The most electrically conductive metal is silver.

Description : Which of the following is arranged in order of decreasing conductivity? (1) Copper, Aluminium, Steel, Silver (2) Aluminium, Silver, Copper, Steel (3) Copper, Silver, Aluminium, Steel (4) Silver, Copper, Aluminium, Steel 

Last Answer : Silver, Copper, Aluminium, Steel

Description : Moisture absorbed in the windings or condensed on the surface of electrical machinery insulation ________. A. is good for long term preserving since most insulation is organic and contains some amount B. ... D. reduces the amount of current supplied or drawn by the machine so horsepower is limited

Last Answer : Answer: B

Description : Which of the following materials is not used for transmission and distribution of electrical power ? (a) Copper (b) Aluminium (c) Steel (d) Tungsten

Last Answer : (d) Tungsten

Description : Which of the following materials is not used for transmission and distribution of electrical power ? (a) Copper (b) Aluminium (c) Steel (d) Tungsten

Last Answer : (d) Tungsten