How does a motor work


In a motor Electrical energy is converted into Mechanic […]

In a motor Electrical energy is converted into Mechanical energy.

The principle is that whenever a current carrying conductor is placed in a magnetic field, the conductor experiences a force across it which causes rotating torque.

For example if we consider a 3-phase induction motor, the stator carries field winding which creates magnetic field and rotor carries armature winding. For a cage rotor the rotor is made up of bar conductors whose end rings are shorted to make a closed path. Now when 3 phase supply is given to the stator, a rotating field is produced by the inherent characteristics of 3 phase supply and an emf is produced across the rotor conductors by electromagnetic induction. By the interaction of these two fields a rotating torque is produced across the rotor conductor and the motor starts running.

For single phase induction motor phase shift is created using capacitor so that two fields are created with a phase shift and rotating torque can be obtained.

An electric motor uses electrical energy to produce mechanical energy, nearly always by the interaction of magnetic fields and current-carrying conductors. The reverse process, that of using mechanical energy to produce electrical energy, is accomplished by a generator or dynamo. Traction motors used on vehicles often perform both tasks.

Electric motors are found in a myriad of uses such as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and computer disk drives, among many other applications. Electric motors may be operated by direct current from a battery in a portable device or motor vehicle, or from alternating current from a central electrical distribution grid. The smallest motors may be found in electric wristwatches. Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses. The very largest electric motors are used for propulsion of large ships, and for such purposes as pipeline compressors, with ratings in the thousands of kilowatts. Electric motors may be classified by the source of electric power, by their internal construction, and by application.