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
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
Answer :
The armature voltage control of D.C. motor provides constant torque drive.
asked
Mar 20, 2018
by
anonymous
Answer :
For a D.C. shunt motor if the excitation is changed torque will change but power will remain constant.
asked
Mar 20, 2018
by
anonymous
Answer :
The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.
asked
Mar 20, 2018
by
anonymous
Answer :
As the load is increased the speed of D.C. shunt motor will reduce slightly.
asked
Mar 20, 2018
by
anonymous
Answer :
In a D.C. shunt motor, speed is independent of armature current.
asked
Mar 20, 2018
by
anonymous
Answer :
The speed of a D.C. shunt motor more than its full-load speed can be obtained by decreasing the field current.
asked
Mar 20, 2018
by
anonymous
Answer :
If the field of a D.C. shunt motor gets opened while motor is running the motor will attain dangerously high speed.
asked
Mar 20, 2018
by
anonymous
Description : Armature control of DC motor
Answer :
Armature control of DC motor
Description : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be
Answer :
A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V
asked
May 8, 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 :
If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens this will make armature to take heavy current, possibly burning it.
asked
Mar 20, 2018
by
anonymous
Answer :
If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.
asked
Mar 20, 2018
by
anonymous
Answer :
Torque developed by a D.C. motor depends upon magnetic field, active length of the conductor, current flow through the conductors, number of conductors, radius of armature.
asked
Mar 20, 2018
by
anonymous
Answer :
The current drawn by the armature of D.C. motor is directly proportional to the torque required.
asked
Mar 20, 2018
by
anonymous
Description : DC shunt motor
Answer :
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asked
Apr 23, 2020
by
anonymous
Description : If field current is decreased in shunt dc motor, the speed of the motor (a) remains same. (b) increases. (c) decreases. (d) none of the above.
Answer :
increases
asked
Aug 25, 2019
by
anonymous
Description : State any four applications of DC shunt motor.
Answer :
Applications of DC shunt motor: 1) Lathe machines 2) drilling machines 3) milling machines 4) Printing machinery 5) Paper industry 6) centrifugal and reciprocating pumps 7) blowers 8)fans
asked
Jul 27, 2019
by
anonymous
Description : Why does the speed of a DC shunt motor decrease as the load increases?
Answer :
Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.
asked
Jul 5, 2019
by
anonymous
Description : DC motor gross torque example
Answer :
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asked
Apr 24, 2020
by
anonymous
Description : Why a dc series motor has a high starting torque?
asked
Mar 15, 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 :
In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to 25% of the previous value.
asked
Mar 20, 2018
by
anonymous
Answer :
Speed torque characteristic of a repulsion induction motor is similar to that of a D.C. compound motor.
asked
Mar 20, 2018
by
anonymous
Answer :
In a A.C. series motor armature coils are usually connected to commutator through resistance.
asked
Mar 20, 2018
by
anonymous
Answer :
The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.
asked
Mar 20, 2018
by
anonymous
Description : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be
Answer :
Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be 25 N -m
asked
Apr 29, 2018
by
anonymous
Description : In a double squirrel cage induction motor, good starting torque is produced as (A) Large current flows through the outer high resistance winding. (B) Large current flows through the inner high resistance winding. (C) Small current flows through the outer high resistance winding. (D) Large current flows through the inner low resistance winding.
Answer :
In a double squirrel cage induction motor, good starting torque is produced as Large current flows through the outer high resistance winding.
asked
May 8, 2018
by
anonymous
Description : The torque developed by any 3-phase induction motor at 0.8 p.u. slip is (A) Full-load torque (B) unstable torque (C) starting torque (D) break down
Answer :
The torque developed by any 3-phase induction motor at 0.8 p.u. slip is unstable torque
asked
Apr 28, 2018
by
anonymous
Answer :
For the same H.P. rating and full load speed, following motor has poor starting torque differentially compounded.
asked
Mar 20, 2018
by
anonymous
Answer :
In repulsion motor, maximum torque is developed when brush axis is at 45° electrical to the field axis.
asked
Mar 20, 2018
by
anonymous
Answer :
Capacitor start motor has high torque in starting
asked
Sep 13, 2017
by
anonymous
Answer :
In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.
asked
Mar 20, 2018
by
anonymous
Answer :
In D.C. shunt motors as load is reduced the speed will remain almost constant.
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
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 : 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 :
In a differentially compounded D.C. motor, if shunt field suddenly opens the motor will first stop and then run in opposite direction as series motor.
asked
Mar 20, 2018
by
anonymous
Answer :
If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses.
asked
Mar 20, 2018
by
anonymous
Answer :
In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will remain unchanged.
asked
Mar 20, 2018
by
anonymous
asked
Mar 20, 2018
by
anonymous
Answer :
The purpose of retardation test on D.C. shunt machines is to find out stray losses.
asked
Mar 20, 2018
by
anonymous
Description : In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is :
Answer :
In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is : 0.075
asked
Apr 29, 2018
by
anonymous
Answer :
In a synchronous motor, the armature current has large values for high and low excitation.
Answer :
The armature current of the synchronous motor has large values for low and high excitation.
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