Electrical Motor | Types Classification
and History of Motor
The motor or an electrical
motor is
a device that has brought about one of the biggest advancements in the fields of
engineering and technology ever since the invention of electricity. A motor is nothing but an electro-mechanical
device that converts electrical energy to mechanical energy. Its because of
motors, life is what it is today in the 21st century. Without motor we had
still been living in Sir Thomas Edison’s Era where the only purpose of
electricity would have been to glow bulbs. There are different types
of motor have
been developed for different specific purposes.
In
simple words we can say a device that produces rotational force is a motor. The
very basic principal of functioning of an electrical
motor lies
on the fact that force is experienced in the direction perpendicular to
magnetic field and the current, when field and electric current are made to interact with each other.
Ever since the invention of motors, a lot of advancements has taken place in
this field of engineering and it has become a subject of extreme importance for
modern engineers. This particular webpage takes into consideration, the above
mentioned fact and provides a detailed description on all major electrical
motors and motoring parts being used in the present era.
Classification or Types of Motor
The
primary classification of motor or types
of motor can
be tabulated as shown below,
History of Motor
In
the year 1821 British scientist Michael Faraday explained the conversion of
electrical energy into mechanical energy by placing a current carrying
conductor in a magnetic field which resulted in the rotation of the conductor
due to torque produced by the mutual action of electrical current and field. Based on his principal the
most primitive of machines a D.C.(direct current) machine was designed by
another British scientist William Sturgeon in the year 1832. But his model was
overly expensive and wasn’t used for any practical purpose. Later in the year
1886 the first electrical motor was invented by scientist Frank Julian Sprague.
That was capable of rotating at a constant speed under a varied range of load,
and thus derived motoring action.
Among
the four basic classification of motors mentioned above the DC motor as the name suggests, is the only one
that is driven by direct current. It’s the most primitive version of the
electric motor where rotating torque is produced due to flow of electric current through the conductor inside a magnetic
field.
Rest
all are A.C. electrical motors, and are driven by alternating current, for e.g.
the synchronous motor, which always runs at synchronous speed. Here the rotor
is an electro – magnet which is magnetically locked with stator rotating
magnetic field and rotates with it. The speed of these machines are varied by
varying the frequency (f) and number of poles (P), as Ns =
120 f/P.
In
another type of AC motor where rotating magnetic field cuts the rotor
conductors, hence circulating current induced in these short circuited rotor
conductors. Due to interaction of the magnetic field and these circulating
currents the rotor starts rotates and continues its rotation. This is induction
motor which is also known as asynchronous motor runs at a speed lesser than
synchronous speed, and the rotating torque, and speed is governed by varying
the slip which gives the difference between synchronous speed Ns ,
and rotor speed speed Nr,
It runs governing the
principal of EMF induction due to varying flux density, hence the name
induction machine comes. Single phase induction motor like a 3 phase, runs by
the principal of emf induction due to flux, but the only difference is, it runs
on single phase supply and its starting methods are governed by two well
established theories, namely the Double Revolving field theory and the Cross
field theory.
Apart from the four basic
types of motor mentioned above, there are several types Of special electrical
motors like Linear Induction motor(LIM),Stepper motor, Servo motor etc with
special features that has been developed according to the needs of the industry
or for a particular particular gadget like the use of hysteresis motor in hand
watches because of its compactness.
Working
of Electric Motor
0 Comments