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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 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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Description :

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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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 number of mechanical degrees and electrical degrees will be the same when number of poles is 2.

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

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

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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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340 views 1 answer
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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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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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A D.C. generator can be considered as rotating amplifier.

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

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

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

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

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

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Description :

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. ?

Answer :

Wave winding

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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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170 views 1 answer
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The critical resistance of the D.C. generator is the resistance of field.

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

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

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Description :

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

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Description :

In a DC shunt generator working on load, the brushes are moved forward in the direction of rotation, as a result of this, commutation will   (a) Improve but terminal voltage will fall   (b) Worsen and terminal voltage will fall   (c) Improve and terminal voltage will rise   (d) worsen and terminal voltage will rise 

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In a DC shunt generator working on load, the brushes are moved forward in the direction of rotation, as a result of this, commutation will Improve but terminal voltage will fall 

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329 views 1 answer
Description :

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.

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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Description :

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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Description :

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

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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Description :

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

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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Brushes of D.C. machines are made of carbon.

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Description :

A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly?

Answer :

A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly 240 V.

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Description :

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

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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Description :

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

Answer :

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

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Description :

What is the difference between an AC and DC generator?

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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290 views 1 answer
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What is the principle of DC generator?

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Description :

Why is the armature of DC generator laminated?

Answer :

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

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154 views 1 answer
Description :

Answer :

Welding generator will have lap winding.

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61 views 1 answer
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In D.C. generators, the brushes on commutator remain in contact with conductors which lie under interpolar region.

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197 views 1 answer
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Answer :

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

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85 views 1 answer
Description :

There is a bridge besides a river. Two friends Arun and varun started their journey from place L, moved to the garden located at another place M & then returned to place L. Arun moves by swimming at a speed of 30 km/hr while Varun sails on a boat at a speed of about 24km/hr. If the flow of water current is at the speed of 12km/hr, what will be the average speed of boat sailor? A) 36 B) 18 C) 24 D) 48 

Answer :

ANSWER:B Explanation: As Arun swims both the ways at the speed of 30km/hr, the average speed of swimming is 30 km/hr Being a boat sailor, varun moves downstream at speed =24 +12=36km/hr and upstream at speed = 24-12= ... Upstream Speed])] = (36*12)/0.5(36+12) km/hr = 432/24 km/hr = 18 km/hr

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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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A separately excited generator as compared to a self-excited generator is amenable to better voltage control, more stable, has exciting current independent of load current.

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Description :

Suppose you are checking student's answer books, all of a sudden you have finished red refill. You call an student and order him to bring a refill. What would you like to do in such a situation? Options: A) You will give him required money for the purpose B) You will return the money when student show courteous gesture C) You think that students money is teachers own money D) You will feel ashamed when you will be paying for such a small amount

Answer :

A) You will give him required money for the purpose 

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

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Description :

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?

Answer :

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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