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What is the principle of DC motor?

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Description : What is the principle of DC generator?

Description : What is the principle of synchronous motor?

Description : What is the principle of AC motor?

Description : Explain the working principle of induction motor. 

Answer : Working principle of induction motor: * When the motor is excited with three-phase supply, three-phase stator winding carries three-phase currents & produces a rotating magnetic field of constant magnitude and ... , which tend to move the rotor in the same direction as the rotating magnetic field. 

Description : State the principle of operation of d.c. motor.

Answer : When a current carrying conductor is placed in a magnetic field, the conductor experiences the force. The magnitude of force is given by F = BIL newton  where F – Force   B – maximum flux density   I – Current   L – Length of conductor

Answer : A hysteresis motor works on the principle of hysteresis loss.

Description : What would happen if a DC motor was supplied with AC ?

Answer : With three phase induction motor, humming and not rotate, but if single phase universal motor like air blower, home mixture, motor run on constant speed..speed variation not possible...

Description : What are the advantages of DC series motor?

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

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 : 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  

Description : A separately excited dc motor operating in first quadrant is fed from 3-phase semi -converter free -wheeling diode is open circuited, then the motor :  (A) can be operated in first quadrant (B) ... in first & second quadrants (C) can be operated in first & fourth quadrants (D) cannot be operated

Answer : A separately excited dc motor operating in first quadrant is fed from 3-phase semi -converter free -wheeling diode is open circuited, then the motor : can be operated in first & fourth quadrants

Description : In a DC motor, it is important to place the brushes along ______ A) Magnetic Neutral Axis B) Normal Geometric Axis C) Nominal Geometric Axis D) None of these

Answer : In a DC motor, it is important to place the brushes along Magnetic Neutral Axis

Description : In a 4-pole wave winding connected dc motor, the cross-magnetizing AT/pole for a brush shift of θ radians (A) Armature amp-conductors × (θ/360o) (B) Armature amp-turns × (θ/360o) (C) Armature amp-conductors × (1/4 - θ/360o) (D) Armature amp-conductors × (1/8 - θ/360o)

Answer : In a 4-pole wave winding connected dc motor, the cross-magnetizing AT/pole for a brush shift of θ radians Armature amp-conductors × (1/8 - θ/360o)

Description : Which type of starter is used to start the DC motor?

Description : Why dc series motor should not be started at no load?

Description : Why a dc series motor has a high starting torque?

Description : What is the RPM of a DC motor?

Description : What are the speed control methods of dc motor?

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

Description : State at least one function and the material used for the following parts of DC Motor.

Answer : Part Function Material Yoke -Provides mechanical support for poles -Acts as protecting cover for machine -Provides path for magnetic flux Cast Iron OR Cast Steel Field Winding - ... Pole core  Provides mechanical support to field winding. Cast Iron OR Cast Steel

Description : State the modification to be done in dc series motor to work satisfactorily as ac series motor. State applications of ac series motor.

Answer : Modifications are necessary in a dc series motor so that it operates satisfactorily on ac supply. The modifications are as follows:  1) AC series motor is built with a few field turns as ... and grinders 5) High speed vacuum cleaners 6) Sewing machines 7) Food processors 8) Drilling machine 

Description : DC motor gross torque example

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 : 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 : DC motor brake test numerical

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 : Brake test on DC series 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 : 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 : 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

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

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 : 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

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

Description : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) ... proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α

Answer : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ

Description : In DC motor iron losses are occurred in?

Answer : In DC motor iron losses are occurred in the armature.

Description : Why DC motor is used for traction?

Answer : Induction motor is a AC motor it is also known as asynchronous motor .

Description : Chopper controlled DC motor

Answer : Chopper controlled DC motor

Description : Armature control of DC motor

Answer : Armature control of DC motor

Description : Field control of DC motor

Answer : Field control of DC motor

Description : Separately Excited DC motor

Answer : Separately Excited DC motor

Description : Four Quadrant Operation Of DC Motor

Answer : Four Quadrant Operation Of DC Motor

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

Description : Explain the necessity of starter for D.C. motor. State various types of D.C. motor starter. 

Answer : Necessity of Starter for D.C. Motor: Armature current is given by equation Ia = (V−Eb)/Ra i) If the motor is at standstill or rest, back emf Eb is zero (as Eb= ZNP/(60A), at start speed N ... . Types of D.C. motor starters: i) Two point starter ii)Three point starter iii) Four point starter

Description : A d.c. motor can be looked upon as d.c. generator with the power flow?

Answer : A d.c. motor can be looked upon as d.c. generator with the power flow reversed.

Description : The Eb/V ratio of a d.c. motor is an indication of its?

Answer : The Eb/V ratio of a d.c. motor is an indication of its efficiency.

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.

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.

Description : In a d.c. motor, unidirectional torque is produced with the help of

Answer : Commutator provides unidirectional torque and pulsating dc

Answer : Series motor has got maximum self relieving property.

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