# The condition for maximum efficiency for a D.C. generator is?

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

## Related questions

Answer : D.C. generators are normally designed for maximum efficiency around full-load.

Answer : Generators for peak load plants are usually designed for maximum efficiency at 50 to 75 percent full load.

Description : For a transformer, operating at constant load current, maximum efficiency will occur at?

Answer : For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.

Answer : An ideal transformer will have maximum efficiency at a load such that copper loss equal to iron loss.

Answer : Transformer efficiency is maximum when copper losses are equal to iron losses.

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

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

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

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

Answer : A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be about 2 V.

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

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

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

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

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

Answer : If a D.C. generator fails to build up the probable cause could not be field resistance less than the critical resistance.

Answer : In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when there is no load on|he generator.

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

Answer : In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when number of poles is 2.

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

Answer : In a D.C. generator the ripples in the direct e.m.f. generated are reduced by using carbon brushes of superior quality.

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

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

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.

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.

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

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

Description : State maximum power transfer theorem for DC circuit.

Answer : Maximum power transfer theorem for DC circuit: The maximum power transfer theorem states that the source or a network transfers maximum power to load only when the load resistance is equal ... removed (disconnected) ii) All internal independent sources are replaced by their internal resistances.

Answer : Series motor has got maximum self relieving property.

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.

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

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.

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

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

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

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

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

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.  ... 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.

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.

Description : What is the principle of DC generator?

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

Answer : Field coils of DC generator are usually made of copper.

Description : Why is the armature of DC generator laminated?

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

Description : The necessary and sufficient condition for a rational function of, T(s) to be driving point impedance of an RC network is that all poles and zeros should be

Answer : The necessary and sufficient condition for a rational function of, T(s) to be driving point impedance of an RC network is that all poles and zeros should be simple and and lie on the negative axis in the s -plane

Description : The condition for the validity under Ohm's law is that?

Answer : The condition for the validity under Ohm's law is that resistance must be uniform.

Answer : An exciter for a turbo generator is a shunt generator.

Description : What is race around condition in JK flip flop and how it can be eliminated?

Answer : For the racing around to take place, it is necessary to have the enable input high along with J=K=1. As the enable input remains high for a long time in a JK latch, the problem of ... to zero. Hence the multiple toggling cannot take place. Thus the edge triggering avoids the race around condition.

Description : Explain working of n-p-n transistor in unbiased condition.

Answer : Construction of NPN transistor: For an unbiased transistor no external power supplies are connected to it. Base is sandwiched between collector & emitter terminal. It is thin & lightly doped ... providing external power supply to transistor & this process is known as Biasing.

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

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