Description : What are the speed control methods of dc motor?
Answer :
Field control of DC motor Armature control of DC motor
asked
Dec 16, 2017
by
anonymous
Description : Armature control of DC motor
Answer :
Armature control of DC motor
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
Answer :
The armature voltage control of D.C. motor provides constant torque drive.
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
Description : From which material field coils of DC generator are made of?
Answer :
Field coils of DC generator are usually made of copper.
asked
Mar 3, 2018
by
anonymous
Description : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque (1) Decreases (2) Increases (3) Remains constant (4) None of the above
Answer :
The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque Increases
asked
May 1, 2018
by
anonymous
Answer :
Series motor has the poorest speed control.
asked
Mar 20, 2018
by
anonymous
Answer :
Speed control of a universal motor is achieved by varying field flux with tapped field windings, connecting rheostat in series, applying variable voltage by means of silicon controlled rectifier, applying variable voltage by means of variable auto-transformer.
asked
Mar 20, 2018
by
anonymous
Answer :
The speed control of universal motor used for sewing machines is by varying the resistance.
asked
Mar 20, 2018
by
anonymous
Description : speed control methods of three phase induction motor?
Answer :
Speed control of three phase induction motor
Answer :
In a shaded pole single-phase motor, the revolving field is produced by the use of shading coils.
asked
Mar 20, 2018
by
anonymous
Answer :
If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.
asked
Mar 20, 2018
by
anonymous
Description : An electric motor in which both stator field and rotor rotates with same speed is called?
Answer :
An electric motor in which both stator field and rotor rotates with same speed is called synchronous motor.
asked
Mar 18, 2018
by
anonymous
Description : If the field of synchronous motor is under excited, power factor will be?
Answer :
If the field of synchronous motor is under excited, power factor will be lagging.
asked
Mar 18, 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
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 the function of following parts of DC motor : i) Yoke ii) Poles iii) Field winding iv) Commutator.
Answer :
Function : i) Yoke: The yoke serves the following two purposes. i) It supports the other components such as poles and provides mechanical protection for whole machine. ii) It forms a part of ... one pole to another and thus to help the motor to develop a continuous and unidirectional torque
asked
Jul 30, 2019
by
anonymous
Description : Describe the reason of using dc series motor for electric trains.
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
asked
Sep 18, 2018
by
anonymous
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 : 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 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
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
Answer :
The function of a brush and commutator arrangement in a dc motor is to produce unidirectional torque
asked
Apr 29, 2018
by
anonymous
Description : What is the RPM of a DC motor?
asked
Mar 15, 2018
by
anonymous
Answer :
Induction motor is a AC motor it is also known as asynchronous motor .
asked
Sep 9, 2017
by
anonymous
Description : Separately Excited DC motor
Answer :
Separately Excited DC motor
Description : Four Quadrant Operation Of DC Motor
Answer :
Four Quadrant Operation Of DC Motor
Description : Speed control of the motor using TRIAC
Answer :
Speed control of the motor using TRIAC: This basic phase triggering circuit uses the triac in series with the motor across an AC sinusoidal supply. The variable resistor, VR1 is used ... meaning that it may not trigger at the exact same point for each positive and negative half cycle.
asked
Oct 13, 2019
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 :
Magnetic field in a D.C. generator is produced by electromagnets.
asked
Mar 20, 2018
by
anonymous
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.
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
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
asked
Mar 20, 2018
by
anonymous
Answer :
At the instant of starting when a D.C. motor is put on supply, it behaves like a low resistance circuit.
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
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
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.
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
Answer :
As the load is increased the speed of D.C. shunt motor will reduce slightly.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Answer :
Sparking, is discouraged in a D.C. motor because commutator gets damaged.
asked
Mar 20, 2018
by
anonymous
Answer :
D.C. Series motor is generally preferred for cranes and hoists.
asked
Mar 20, 2018
by
anonymous
asked
Mar 20, 2018
by
anonymous
Answer :
Sparking at the commutator of a D.C. motor may result in damage to commutator segments, damage to commutator insulation, increased power consumption.
asked
Mar 20, 2018
by
anonymous
Answer :
Cumulatively compounded D.C. motor will be suitable along with flywheel for intermittent light and heavy loads.
asked
Mar 20, 2018
by
anonymous
Answer :
Differentially compounded D.C. motor has got maximum self loading property.
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
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 :
The speed of a D.C. series motor is inversely proportional to the armature current.
asked
Mar 20, 2018
by
anonymous