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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.

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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.

Answer : If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.

Answer : The armature may burn if the back e.m.f. of a D.C. motor vanishes suddenly.

Description : Do AC induction motors have back EMF?

Answer : In D.C. shunt motors as load is reduced the speed will remain almost constant.

Answer : When two D.C. series motors are connected in parallel, the resultant speed is normal speed.

Answer : In a D.C. shunt motor, speed is independent of armature current.

Answer : The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.

Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly.

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

Answer : D.C. shunt motors are used for driving machine tools.

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.

Description : What is the back EMF of a dc motor?

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.

Description : In case of conductively compensated D.C. series motors, the compensating winding is provided?

Answer : In case of conductively compensated D.C. series motors, the compensating winding is provided in series with armature winding.

Answer : Starters are used with D.C. motors because to restrict armature current as there is no back e.m.f. while starting.

Answer : The speed of a D.C. shunt motor more than its full-load speed can be obtained by decreasing the field current.

Description : The back emf of synchronous motor depends on?

Answer : The back emf of synchronous motor depends on load angle.

Description : The counter e.m.f. of a d.c. motor?

Answer : The counter e.m.f. of a d.c. motor helps in energy conversion.

Answer : When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.

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.

Description : What is back EMF in inductor?

Description : What is the back EMF in Transformers?

Description : What is back emf? 

Answer : Back EMF: When a current carrying conductor is placed in a magnetic field it experiences a force; when it moves due to the force it (conductor) cuts the magnetic field due to which an emf is ... (hence the applied armature voltage) is opposed by the induced emf which is therefore called as Back emf.

Description : What is back EMF of synchronous motor?

Description : What is the back EMF of the motor?

Description : What is the back EMF?

Answer : When the armature of a d.c. motor rotates under the influence of the driving torque, the armature conductors move through the magnetic field and hence e.m.f. is induced in them as in a generator. The ... that energy conversion in a d.c. motor is only possible due to the production of back emf.

Answer : Differentially compound D.C. motors can find applications requiring low starting torque.

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 : For a D.C. shunt motor if the excitation is changed torque will change but power will remain constant.

Answer : The armature torque of the D.C. shunt motor is proportional to armature current.

Answer : If the field of a D.C. shunt motor gets opened while motor is running the motor will attain dangerously high speed.

Description : As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit?

Answer : As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit a resistance is connected in series with armature.

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

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

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.

Answer : The purpose of retardation test on D.C. shunt machines is to find out stray losses.

Description : The speed of a D.C. motor can be controlled by varying  1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above

Answer : The speed of a D.C. motor can be controlled by varying  1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above

Answer : The speed of a D.C. series motor is inversely proportional to the armature current.

Description : Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above

Answer : Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above

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 : What are the speed control methods of dc motor?

Answer : Field control of DC motor Armature control of DC motor

Answer : During rheostat braking of D.C. series motors motor is run as a generator.

Answer : The D.C. motors preferred for traction applications beacuse the speed is inversely proportional to the torque and the torque is proportional to square of armature current.

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.

Description : Why are DC motors used in trains and not AC motors ?

Answer : The reason is torque. torque is inversely proportional to speed..i.e when th knowe train comes to rest position to motion.. initial speed is zero..so it requires high starting torque for ... current will flow through field and armature coils then maximum torque is available at the intial condition.

Description : DC shunt motor

Answer : .embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } .embed-container iframe, .embed-container object, .embed-container embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }

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

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

Answer : E.m.f. of a Weston cell is accurately measured by electrostatic voltmeter.

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