Electric motor

 

Electric motor                                                     

 

An electric motor is rotating machine or device that converts the electrical energy to mechanical energy.

 

An electric motor is consists of a rectangular coil ABCD of insulated copper wire. The coil is placed between the two poles of magnetic field. The rectangular coil of the arms AB and CD are kept in such a manner that both rms are perpendicular to the direction of the magnetic field. The ends of the coil are connected to the two halves P and Q of a split ring. The inner side of the halves are insulated and attached to the axle. The external conducting edges of P and Q touch the two conducting stationary brushes X and Y respectively.

 

Working :--

 

A source of battery is used to enter  the current in the coil through conducting brushes X and flows back to the battery through brush Y.

Now , the current in the arms of the rectangular coil AB is flowing from A to B

And the  current in the arms of the coil CD is flowing from C to D. It means it is opposite direction of the current through the arms of the coil AB .

On applying the fleming’s left hand rule for the direction of the force on a current carrying conductor in a magnetic field.

Due to this , the force acting on arms AB pushes it downwards while the force acting on arms CD pushes it upwards.

Thus the coil and the axle O , mounted free to turn about an axis , rotate anti-clockwise.

After half rotation, Q ix contacted with brush X and P is contacted with Y.

Therefore , the current in the coil gets reversed and flow in the direction of the  DCBA.

A device that is used to reverse the flow of the direction of the flow of the  current in the circuit is known as the commutator.  

In the electric motor, the split rings behaves as commutator.

When the current is reversed , then the direction of the force acting on the both arm AB and CD is also reversed.

And now,  the arm AB of the coil that was pushed down in the earlier. And now it is pushed up .

And the arm CD of the coil that was pushed up in the earlier. And now it is pushed down.

Therefore , the coil and the axle rotate half a turn more in the same direction. the reversing of the current is repeated at each half rotation, giving rise to a continuous rotation of the coil and the axle.

And the soft iron core on which the coil is wound plus the coil ic called armature. This enhances  the power of the motor.

 

A simple electric motor has six parts:--

 

1.  Armature or rotor

2.  Commutator

3.  Brushes

4.  Axle

5.  Field magnet

6.  DC power supply or battery

 

1. Armature or rotor:--

                                        It is a component of the electric machine like electric motor or electric generator that carries alternating current (AC).the armature winding conduct AC on DC (direct current) machines  via a commutator action which periodically reverse current direction ) or due to electronic commutation (like in the brushless DC motors).

 

2.  Commutator:--

                                A device that is used to reverse the flow of the direction of the flow of the  current in the circuit is known as the commutator. In the electric motor, the split rings behaves as commutator.

 

3. Brushes:--

                       Brushes are the electrical contact which produce the electric current between the stationary wires and moving parts most commonly in a rotating shaft.

 

4. Axle:--

            the two halves of the ring have a resistive coating in the inner of the their surfaces. And they are tightly fitted inti the axle. And the main function of the Axle is used to rotate with the coil.

 

 

 

5.  Field magnet:--

                            the armature coil is placed between the the poles (N or S) of strong horse shoe magnet which provides strong magnetic field.

 

6. Battery or DC power supply :--

                                                           Battery supplies current to the armature coil. It is connected with the carbon brushes.