205 views
0 answers
asked
Mar 20, 2018
by
anonymous

A 200 V DC machine supplies 20 A at 200 V as a generator. The armature resistance is 0.2 Ohm. If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by 10%, the ratio of motor speed to generator speed is
Last Answer : A 200 V DC machine supplies 20 A at 200 V as a generator. The armature resistance is 0.2 Ohm. If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by 10%, the ratio of motor speed to generator speed is 0.87
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127 views
1 answer
asked
May 8, 2018
by
anonymous

Last Answer : The armature core of a D.C. generator is usually made of silicon steel.
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153 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The demagnetising component of armature reaction in a D.C. generator reduces generator e.m.f.
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123 views
1 answer
asked
Mar 20, 2018
by
anonymous

The armature reaction in a synchronous generator supplying leading power factor load is (A) magnetizing (B) demagnetizing (C) demagnetizing and cross-magnetizing (D) magnetizing and cross-magnetizing
Last Answer : The armature reaction in a synchronous generator supplying leading power factor load is magnetizing and cross-magnetizing
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96 views
1 answer
asked
Apr 28, 2018
by
anonymous
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Why poles of dc machine are laminated?
Last Answer : Poles of DC machines are laminated to reduce the eddy current losses in the poles.
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112 views
1 answer
asked
Apr 27, 2020
by
anonymous
.jpg)
A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is
Last Answer : A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is 36 Ohm
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332 views
1 answer
asked
May 3, 2018
by
anonymous

In dc machines, the armature windings are placed on the rotor because of the necessity for (1) electromechanical energy conversion (2) generation of voltage (3) commutation (4) development of torque
Last Answer : 3 Commutation
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292 views
2 answers
asked
May 1, 2018
by
anonymous

The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is (1) 1000V (2) 100V (3) 600V (4) 10,000V
Last Answer : The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is 1000V
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370 views
1 answer
asked
Apr 29, 2018
by
anonymous

Aluminium is not used as winding wire for the armature of a dc machine because (1) aluminium has low resistivity (2) a large winding space is taken by aluminium conductors and creates ... ) the thermal conductivity of aluminium is low (4) aluminium has low conductivity as compared to copper
Last Answer : Aluminium is not used as winding wire for the armature of a dc machine because (2) a large winding space is taken by aluminium conductors and creates jointing problems (3) the thermal conductivity of aluminium is low (4) aluminium has low conductivity as compared to copper
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621 views
1 answer
asked
Apr 29, 2018
by
anonymous

Armature control of DC motor
Last Answer : Armature control of DC motor
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162 views
2 answers
asked
Aug 9, 2017
by
anonymous

Last Answer : Armature reaction in a generator results in demagnetisation of leading pole tip and magnetisation of trailing pole tip.
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216 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : The armature voltage control of D.C. motor provides constant torque drive.
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92 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The armature torque of the D.C. shunt motor is proportional to armature current.
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210 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.
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367 views
1 answer
asked
Mar 20, 2018
by
anonymous

The fall in speed of a dc generator due to increase in load can be corrected by (1) cooling the armature.. (2) increasing the excitation. (3) reducing the load voltage. (4) increasing the input to the prime mover
Last Answer : It can be corrected by increasing the input to the prime mover.
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355 views
2 answers
asked
May 1, 2018
by
anonymous

In a DC generator the windings of interpoles are connected : (A) in series with main field winding, to create a pole,of same polarity as the main pole ahead in the direction of rotation. ... winding, to create a pole of opposite polarity as the main pole ahead in the direction of rotation.
Last Answer : In a DC generator the windings of interpoles are connected : in series with the armature winding, to create a pole of same polarity as the main pole ahead in the direction of rotation.
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123 views
1 answer
asked
Apr 29, 2018
by
anonymous

What is the difference between an AC and DC generator?
Last Answer : The generator which generates DC voltage is called DC generator and generator which generates AC voltage is called AC generator (or) Alternator. In DC generator armature is rotated and field winding ... generator. A DC generator can generate low voltages but an AC generator can generate upto 11kv.
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315 views
1 answer
asked
Mar 15, 2018
by
anonymous

What is the principle of DC generator?
Last Answer : principle
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80 views
1 answer
asked
Mar 15, 2018
by
anonymous

From which material field coils of DC generator are made of?
Last Answer : Field coils of DC generator are usually made of copper.
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118 views
1 answer
asked
Mar 3, 2018
by
anonymous

For a D.C. generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f. ?
Last Answer : Wave winding
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141 views
1 answer
asked
Mar 20, 2018
by
anonymous

The normal value of the armature resistance of a d.c. motor is?
Last Answer : The normal value of the armature resistance of a d.c. motor is 0.5.
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2.9k views
1 answer
asked
Mar 26, 2018
by
anonymous

Last Answer : Open circuited armature coil of a D.C. machine is identified by the scarring of the commutator segment to which open circuited coil is connected and indicated by a spark completely around the commutator.
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159 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.
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203 views
1 answer
asked
Mar 20, 2018
by
anonymous

State the function of commutator in DC generator and name the material used for commutator.
Last Answer : Function of Commutator: Commutator converts AC induced in armature winding into DC for external load. Material: i) Commutator segments are made up of Copper. ii) Commutator segments are insulated from each other by Mica.
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256 views
1 answer
asked
Jul 27, 2019
by
anonymous

The eddy current loss in a dc generator is 400 W at 40 Hz frequency of reversal and constant flux density. When frequency is increased to 50 Hz., eddy current loss is : (A) 256 W (B) 320 W (C) 500 W (D) 625 W
Last Answer : The eddy current loss in a dc generator is 400 W at 40 Hz frequency of reversal and constant flux density. When frequency is increased to 50 Hz., eddy current loss is : 625 W
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103 views
1 answer
asked
Apr 30, 2018
by
anonymous

The terminal characteristics of a dc generator suitable for electric welders is (A) separately excited generator (B) shunt generator (C) series generator (D) differentially compounded generator
Last Answer : The terminal characteristics of a dc generator suitable for electric welders is differentially compounded generator
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105 views
1 answer
asked
Apr 28, 2018
by
anonymous

How to Clean Laminated Floors ?
Last Answer : How to Clean Laminated Floors Laminated floors offer beauty and style just like hardwood or stone floors, but with much easier maintenance. Made with dense fibers and wood particles, the flooring material is ... indoors. Clean up spills as soon as possible for easier removal, and you're all set.
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2 views
1 answer
asked
May 9, 2021
by
anonymous

Laminated cores, in electrical machines, are used to reduce?
Last Answer : Laminated cores, in electrical machines, are used to reduce eddy current loss.
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104 views
1 answer
asked
Mar 25, 2018
by
anonymous

In AC. circuits, laminated iron is invariably used in order to?
Last Answer : In AC. circuits, laminated iron is invariably used in order to reduce eddy current loss.
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105 views
1 answer
asked
Mar 25, 2018
by
anonymous

Why does the core of a transformer need to be laminated?
Last Answer : Transformer cores are laminated to reduce eddy current loss.
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122 views
1 answer
asked
Mar 14, 2018
by
anonymous

Last Answer : Transformer core is laminated to reduce Eddy current losses.
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112 views
1 answer
asked
Sep 30, 2017
by
anonymous

Last Answer : The critical resistance of the D.C. generator is the resistance of field.
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555 views
1 answer
asked
Mar 21, 2018
by
anonymous

If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be?
Last Answer : If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be zero.
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277 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be about 2 V.
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483 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : In a level compounded D.C. generator, full load terminal voltage is equal to no-load terminal voltage.
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129 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : In a D.C. generator in case the resistance of the field winding is increased, then output voltage will decrease.
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251 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : A D.C. generator can be considered as rotating amplifier.
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73 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : In a D.C. generator, the critical resistance refers to the resistance of field.
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136 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : Flashing the field of D.C. generator means creating residual magnetism by a D.C. source.
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95 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : If a D.C. generator fails to build up the probable cause could not be field resistance less than the critical resistance.
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128 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when there is no load on|he generator.
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226 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : The e.m.f. generated in a D.C. generator is directly proportional to speed of armature.
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601 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when number of poles is 2.
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785 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : D.C. generator generally preferred for charging automobile batteries is long shunt compound generator.
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239 views
1 answer
asked
Mar 20, 2018
by
anonymous

91 views
0 answers
asked
Mar 20, 2018
by
anonymous

Last Answer : In a D.C. generator the ripples in the direct e.m.f. generated are reduced by using carbon brushes of superior quality.
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224 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : ni bondha
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430 views
2 answers
asked
Mar 20, 2018
by
anonymous

Last Answer : If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be crossmagnetisation as well as demagnetising.
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148 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be 8.
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258 views
1 answer
asked
Mar 20, 2018
by
anonymous
