# If the field of a D.C. shunt motor gets opened while motor is running?

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

## Related questions

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Last 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.

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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

Last 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

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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

Last 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

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

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

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

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

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Last 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.

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

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

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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.

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Description : Field control of DC motor

Last Answer : Field control of DC motor

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Description : DC shunt motor

Last 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%; }

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Description : State any four applications of DC shunt motor.

Last 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

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Description : Why does the speed of a DC shunt motor decrease as the load increases?

Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.

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

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Description : A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave?

Last 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.

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Last 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.

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Last 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.

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

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Last 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.

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Last 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.

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

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

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Last Answer : In a manual shunt motor starter over load relay is connected in series and no volt relay in parallel with the load.

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

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

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Last Answer : In a shaded pole single-phase motor, the revolving field is produced by the use of shading coils.

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Last Answer : If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.

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Description : An electric motor in which both stator field and rotor rotates with same speed is called?

Last Answer : An electric motor in which both stator field and rotor rotates with same speed is called synchronous motor.

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Description : If the field of synchronous motor is under excited, power factor will be?

Last Answer : If the field of synchronous motor is under excited, power factor will be lagging.

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Description : A 4-pole, dc shunt motor working on 250V takes a current of 2A when running at no load on 1000 rpm. Calculate its back emf and speed at load if the motor takes 51A. Armature and shunt field resistance are 0.2Ω and 250Ω respectively

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

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Description : Describe the reason of using dc series motor for electric trains.

Last Answer : Electric trains require an inverse torque speed characteristics for proper operation. That is a higher torque is required at start (when speed is nil or low) and as the train picks up ... torque - speed characteristics of DC series motors match, these motors are suitable for electric trains

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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 :

Last 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

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Description : The function of a brush and commutator arrangement in a dc motor is to  (1) produce unidirectional torque (2) produce unidirectional current in the armature (3) help in changing the direction of rotation of the armature (4) reduce sparking

Last Answer : The function of a brush and commutator arrangement in a dc motor is to produce unidirectional torque

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Last Answer : If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor.

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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

Last 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

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Last Answer : At the instant of starting when a D.C. motor is put on supply, it behaves like a low resistance circuit.

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Last 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.

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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?

Last 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.

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Last Answer : The armature voltage control of D.C. motor provides constant torque drive.

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Last Answer : Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be cumulatively compounded.

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Last Answer : Sparking, is discouraged in a D.C. motor because commutator gets damaged.

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Last Answer : D.C. Series motor is generally preferred for cranes and hoists.

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Last Answer : (b) Clostridium butylicum Lipase Removal of oil stains

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Last Answer : Sparking at the commutator of a D.C. motor may result in damage to commutator segments, damage to commutator insulation, increased power consumption.

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Last Answer : Cumulatively compounded D.C. motor will be suitable along with flywheel for intermittent light and heavy loads.