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The critical resistance of the D.C. generator is the resistance of field.

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In a D.C. generator, the critical resistance refers to the resistance of field.

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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

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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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In a D.C. generator in case the resistance of the field winding is increased, then output voltage will decrease.

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If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be?

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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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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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In a level compounded D.C. generator, full load terminal voltage is equal to no-load terminal voltage.

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A D.C. generator can be considered as rotating amplifier.

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Flashing the field of D.C. generator means creating residual magnetism by a D.C. source.

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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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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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The e.m.f. generated in a D.C. generator is directly proportional to speed of armature.

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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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D.C. generator generally preferred for charging automobile batteries is long shunt compound generator.

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The armature core of a D.C. generator is usually made of silicon steel.

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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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Magnetic field in a D.C. generator is produced by electromagnets.

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The demagnetising component of armature reaction in a D.C. generator reduces generator e.m.f.

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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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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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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. ?

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Wave winding

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In a D.C. generator, the iron losses mainly take place in armature rotor.

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The condition for maximum efficiency for a D.C. generator is variable losses equal to constant losses.

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The total losses in a well designed D.C. generator of 10 kW will be nearly 500 W.

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In D.C. generators on no-load, the air gap flux distribution in space is flat topped.

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Define the following terms: 1) Virtual height 2) Actual height 3) Critical frequency. 4) Maximum usable frequency.

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1) Virtual height:- The incident and refracted rays follow paths that are exactly the same as they have been if reflection had taken place from a surface located at a greater height, called ... angle of incidence is other than the normal is known as maximum unstable frequency. MUF= fc secθ 

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The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be?

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The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be 580 V.

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The normal value of the armature resistance of a d.c. motor is?

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The normal value of the armature resistance of a d.c. motor is 0.5.

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The starting resistance of a D.C. motor is generally low.

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State the function of commutator in DC generator and name the material used for commutator.

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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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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

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It   can  be  corrected  by  increasing  the  input  to  the  prime  mover.

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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

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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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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.  (B) in series with main field winding, to create a pole of opposite polarity as the main pole ahead in the direction of ... in the direction of rotation.  (D) in series with the armature winding, to create a pole of opposite polarity as the main pole ahead in the direction of rotation.

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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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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

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The terminal characteristics of a dc generator suitable for electric welders is differentially compounded generator

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What is the difference between an AC and DC generator?

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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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What is the principle of DC generator?

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From which material field coils of DC generator are made of?

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Field coils of DC generator are usually made of copper.

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Why is the armature of DC generator laminated?

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The armature of DC generator is laminated to reduce eddy current losses.

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We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be

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We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be 2.4 kOhm

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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

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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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Armature reaction in a generator results in demagnetisation of leading pole tip and magnetisation of trailing pole tip.

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In a separately excited generator supplying rated load the armature reaction is always present.

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A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave will be of 5 Hz.

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In over compounded generator, full load terminal voltage is more than no load terminal voltage.

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In case of a flat compounded generator voltage remains constant irrespective of the load.

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An exciter for a turbo generator is a shunt generator.

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A cumulatively compounded long shunt generator when operating as a motor would be differentially compounded long shunt.

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The purpose of providing dummy coils in a generator is to provide mechanical balance for the rotor.

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