Description : Why is the armature of DC generator laminated?
Answer :
The armature of DC generator is laminated to reduce eddy current losses.
asked
Mar 3, 2018
by
anonymous
Answer :
The armature core of a D.C. generator is usually made of silicon steel.
asked
Mar 20, 2018
by
anonymous
Answer :
The demagnetising component of armature reaction in a D.C. generator reduces generator e.m.f.
asked
Mar 20, 2018
by
anonymous
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
asked
May 8, 2018
by
anonymous
Answer :
A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave will be of 5 Hz.
asked
Mar 21, 2018
by
anonymous
Answer :
Armature reaction in a generator results in demagnetisation of leading pole tip and magnetisation of trailing pole tip.
asked
Mar 21, 2018
by
anonymous
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
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Description : 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
Answer :
The armature reaction in a synchronous generator supplying leading power factor load is magnetizing and cross-magnetizing
asked
Apr 28, 2018
by
anonymous
Description : Why poles of dc machine are laminated?
Answer :
Poles of DC machines are laminated to reduce the eddy current losses in the poles.
asked
Apr 27, 2020
by
anonymous
Answer :
In a D.C. generator, the critical resistance refers to the resistance of field.
asked
Mar 21, 2018
by
anonymous
Answer :
If a D.C. generator fails to build up the probable cause could not be field resistance less than the critical resistance.
asked
Mar 21, 2018
by
anonymous
Answer :
The e.m.f. generated in a D.C. generator is directly proportional to speed of armature.
asked
Mar 21, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Answer :
The critical resistance of the D.C. generator is the resistance of field.
asked
Mar 21, 2018
by
anonymous
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.
asked
Mar 21, 2018
by
anonymous
Answer :
A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be about 2 V.
asked
Mar 21, 2018
by
anonymous
Answer :
In a level compounded D.C. generator, full load terminal voltage is equal to no-load terminal voltage.
asked
Mar 21, 2018
by
anonymous
Answer :
In a D.C. generator in case the resistance of the field winding is increased, then output voltage will decrease.
asked
Mar 21, 2018
by
anonymous
Answer :
A D.C. generator can be considered as rotating amplifier.
asked
Mar 21, 2018
by
anonymous
Answer :
Flashing the field of D.C. generator means creating residual magnetism by a D.C. source.
asked
Mar 21, 2018
by
anonymous
Answer :
In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when there is no load on|he generator.
asked
Mar 21, 2018
by
anonymous
Answer :
In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when number of poles is 2.
asked
Mar 20, 2018
by
anonymous
Answer :
D.C. generator generally preferred for charging automobile batteries is long shunt compound generator.
asked
Mar 20, 2018
by
anonymous
asked
Mar 20, 2018
by
anonymous
Answer :
In a D.C. generator the ripples in the direct e.m.f. generated are reduced by using carbon brushes of superior quality.
asked
Mar 20, 2018
by
anonymous
Answer :
Magnetic field in a D.C. generator is produced by electromagnets.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Answer :
In a D.C. generator, the iron losses mainly take place in armature rotor.
asked
Mar 20, 2018
by
anonymous
Answer :
The condition for maximum efficiency for a D.C. generator is variable losses equal to constant losses.
asked
Mar 20, 2018
by
anonymous
Answer :
The total losses in a well designed D.C. generator of 10 kW will be nearly 500 W.
asked
Mar 20, 2018
by
anonymous
Answer :
The armature torque of the D.C. shunt motor is proportional to armature current.
asked
Mar 20, 2018
by
anonymous
Description : The normal value of the armature resistance of a d.c. motor is?
Answer :
The normal value of the armature resistance of a d.c. motor is 0.5.
asked
Mar 26, 2018
by
anonymous
Answer :
When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.
asked
Mar 20, 2018
by
anonymous
Answer :
The armature voltage control of D.C. motor provides constant torque drive.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Answer :
In D.C. generators on no-load, the air gap flux distribution in space is flat topped.
asked
Mar 21, 2018
by
anonymous
Description : 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
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
asked
May 3, 2018
by
anonymous
Description : 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
Answer :
3 Commutation
asked
May 1, 2018
by
anonymous
Description : 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
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
asked
Apr 29, 2018
by
anonymous
Description : 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 jointing problems (3) the thermal conductivity of aluminium is low (4) aluminium has low conductivity as compared to copper
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
asked
Apr 29, 2018
by
anonymous
Description : Armature control of DC motor
Answer :
Armature control of DC motor
Answer :
In a separately excited generator supplying rated load the armature reaction is always present.
asked
Mar 21, 2018
by
anonymous
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.
asked
Mar 21, 2018
by
anonymous
Answer :
Armature reaction of an unsaturated D.C. machine is crossmagnetising.
asked
Mar 20, 2018
by
anonymous
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.
asked
May 1, 2018
by
anonymous
Description : Laminated cores, in electrical machines, are used to reduce?
Answer :
Laminated cores, in electrical machines, are used to reduce eddy current loss.
asked
Mar 25, 2018
by
anonymous
Description : In AC. circuits, laminated iron is invariably used in order to?
Answer :
In AC. circuits, laminated iron is invariably used in order to reduce eddy current loss.
asked
Mar 25, 2018
by
anonymous
Description : Why does the core of a transformer need to be laminated?
Answer :
Transformer cores are laminated to reduce eddy current loss.
asked
Mar 14, 2018
by
anonymous
Answer :
The commutator segments are connected to the armature conductors by means of copper lugs.
asked
Mar 20, 2018
by
anonymous