## Best And Free Electrical Interview Questions Bank On DC Motor!!

### Here You Can Find The Best And Useful Electrical Interview Questions Which Is Related On DC Motor And You Can Get It The Top Best Questions And Also Its Free Than Read It And Crack Your Interviews!!!

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__Interview Questions On Working Principle Of DC Motor__

__Interview Questions On Working Principle Of DC Motor__

**1) define function of DC Motor???**

Ans: An electric motor is a machine which converts electric energy into mechanical energy.

**2) In d.c. motor conductor is experienced force by whose principle??**

Ans: Fleming's Left-hand Rule

**3)what is the function of commutator in d.c. motor**??

Ans: the function of a commutator in the motor is the same as in the generator. By reversing current in each conductor as it passed from one pole to another, it help to develop a continuous and unidirectional torque.

**4) In lathes machine which type of motor are uses???**

Ans:shunt type d.c. motor

**5)where the series type d.c motor are used??**

Ans:

* For traction work i.e. Electric locomotives

*Rapid transut system

*Trolley, cars etc.

*Cranes and hoists

*Conveyors

**6)For intermittent high torque loads which motor are used??**

Ans: Comulative compound type d.c. motor

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__Interview Questions On Losses in DC Machine__

__1)__list**The losses occurring in dc machines ???**

Ans: listed as below:

(1) copper losses

(2) Magnetic or iron losses

(3) Mechanical losses

(4) Stray load losses

**2) give The various copper losses occurring in the windings ??????**

Ans:

(A) Armature copper loss

(B) Shunt field copper loss

(C) Series field copper loss

(D) Copper loss in interpole winding

(E) Brush contact loss

**3)The armature copper loss is about ______% of totle full load losses amd field copper losses are about ______%of full load losses.???**

Ans:30-40 and 20-30

**4)Magnetic losses is also known as????**

Ans:These losses are also called iron loss or core loss.

**5)magnetic loss consist which losses???**

Ans:Iron losse consists of (1) Hysterisis losses and (2) Eddy current losse.

**6)magnetic loss are about _____of full load losses.???**

Ans: 20% to 30%

**7)explain hysteresis losses in dc machine???**

Ans:Hysterisis losses

This loss is due to reversal of magnetism of the armature core.

These losses pccur in armature core teeth of the dc machine.

Hysteresis losses can be reduced by using core material of silicon steel which has low hysterisis coefficient.

**8)define eddy current???**

Ans:When armature core rotates in magnetic field of poles it also cuts the magnetic flux. Hence an emf is induce in the body of the core according to the low of electromagnetic induction. This emf set up current in the body of the armature core and its know as eddy current

**9)mechanical losses consists which losses???**

Ans:(a) Bearing and brush friction losses

(b) Winding loss or air friction of rotating armature.

These losses are about 10-20% of totle full load losses.

**10)stray losses occurring because of???**

Ans:(1)Distortion of flux because of armature reaction

(2)due to eddy current in conductore

(3)short circuit current in the armature coil undergoing commutation.

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__Interview Questions Related To Armature Reaction__

__Interview Questions Related To Armature Reaction__

**1)The armature magnetic field has how manny effects and which???**

Ans: Two

(1) It demagnetises or weakens the main flux and

(2) It cross-magnetises or distorts.

**2) what is the full form of G. N. A???**

**3)define Magnetic neutral axis???**

**4)what is Leading Pole Tip(LPT)???**

**5) give the fullform of TPT and define TPT???**

It is the end of the pole which comes in contact later with the armature in the direction of rotation.

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Ans: two type (1) single excited and (2) doubly excited

Ans: dW=E.i dt

T=(1/2)*(i^2)*(dL/d§)

Where §=angle

Ans:A magnetic system which is excited by two independent source is called doubly excited magnetic circuit.

Ans:Tm d§ =(1/2)(i^2) dLs + (1/2)(ir^2) dLr +(is) (ir) dM

Where §=anglr

Ir= rotor current

Is= stator current

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__Interview Questions On Different Types Of Magnetic Exciting System__

__Interview Questions On Different Types Of Magnetic Exciting System__

__1)__how many type for Exciting to Magnetic System??Ans: two type (1) single excited and (2) doubly excited

**2)Give the formula of The incremental electrical energy (dWe) due to the flow of current in the Single Excited System??**

**3)Give the formula For angular movements of armature the electromagnetic torque for a linear system ???**

T=(1/2)*(i^2)*(dL/d§)

Where §=angle

**4)What is Doubly Excited Magnetic System??**

**5) Give the example of Doubly Excited Magnetic System??**

Ans:The synchronous machines and d.c. machines .

**6)Give formula for satisfied the energy conversion principle in Doubly Excited Magnetic System??**

Ans: dWe = dWm + dWf

**7)Give the formula of Magnetic torque developed in Doubly Excited Magnetic System??**

Where §=anglr

Ir= rotor current

Is= stator current

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