Question

explain about the working of electric motor.

Answer 1

electric motor is a device which converts electrical energy into mechanical energy. electric motor is used to run many electrical appliances. commonly used motor: DC motor

PRINCIPLE OF ELECTRIC MOTOR:
an electric motor works on the principle that when a rectangular coil is placed in a magnetic field, and current is passed through it then 2 equal and opposite Forces acting on the two sides of the coil tend to rotate it continously.

Answer 2

Theelectric motoris a device which converts electrical energyto mechanical energy. There aremainly threetypes of electric motor.1.DC Motor.2.Induction Motor.3.Synchronous Motor.All of these motors work in more or less same principle.Working of electric motormainly depends upon the interaction ofmagnetic fieldwithcurrent. Now we will discuss the basic operatingprinciple of electric motorone by one for better understanding the subject.Working of DC MotorWorking principle of DC Motormainly depends uponFleming Left Hand rule. In a basicDC motor, an armature is placed in between magnetic poles. If thearmature windingis supplied by an external DC source,currentstarts flowing through the armature conductors. As theconductorsare carrying current inside a magnetic field, they will experience a force which tends to rotate the armature. Suppose armature conductors under N poles of the field magnet, are carrying current downwards (crosses) and those under S poles are carrying current upwards (dots). By applying Fleming’s Left hand Rule, the direction of force F, experiencedby the conductor under N poles and the force experienced by the conductors under S-poles can be determined. It is found that at any instant the forces experienced by the conductors are in such a direction that they tend to rotate the armature.Again, due this rotation the conductors under N-poles comeunder S-pole and the conductors under S-poles come under N-pole. While the conductors go form N-poles to S-pole and S-poles to N-pole, thedirection of current through them, is reversed by means of commutator. Due to this reversal of current, all the conductors come under N-polescarry current in downward direction and all the conductors come under S-poles carry current in upward direction as shown in the figure. Hence, every conductor comes under N-pole experiences force in same direction and same is truefor the conductors come under S-poles. This phenomenon helpsto develop continuous and unidirectional torque.Working of Induction MotorWorking of electric motorin the case ofinduction motoris little bit different fromDC motor. Insingle phase induction motor, when a single phase supply is given to the stator winding, a pulsating magnetic field is produced and in athree phase induction motor, when three phase supply is given to three phase stator winding, a rotating magnetic field is produced. The rotor of an induction motor is either wound type or squirrel cadge type. Whatever may be the type of rotor, the conductorson it are shorted at end to form closed loop. Due to rotating magnetic field, thefluxpasses through the air gap between rotor and stator, sweeps past the rotor surface and so cuts the rotor conductor. Hence according toFaraday’s law of electromagnetic induction, there would be a induced current circulating in the closed rotor conductors. The amount of induced current is proportional to the rate of change of flux linkage with respect to time. Again this rate of change of flux linkage is proportional to the relative speed between rotor and rotating magnetic field. As perLenz lawthe rotor will try to reduce the every cause of producing current in it. Hence the rotor rotates and tries to achieve the speed of rotating magnetic field to reduce the relative speed between rotor and rotating magnetic field.Working of schronous MotorynIn synchronous motor, when balanced three phase supply is given to the stationary three phase stator winding, a rotating magnetic field is produced which rotates at synchronous speed. Now if an electromagnet is placed inside this rotating magnetic field, it is magneticallylocked with the rotating magnetic field and the former rotates with the rotating magnetic field at same speed that is at synchronous speed.