Electrical motors: Sparking innovation and powering the wheels of progress that changed the world!

Electrical motor basic concepts

Hey bloggers!

Did you know that over 75% of the electrical power consumed by industries today is used by electrical motors?

Don't be surprised if I say yes to it, as from factories to household appliances, motors have transformed how to live and work. The invention of electrical motors marked a significant step in the Industrial Revolution, paving the way for modern technology.

Let’s delve into the world of physics and electric motors! Before we learn about the basics of electrical motors, let’s understand electromagnetism and how it is important for the development of electrical motors.

1.        Magnetism

Let’s take a look at the concepts of magnetism -

Magnetism

All magnets share two characteristics: they attract metals such as iron and steel, and they will move to point north-south if nothing obstructs them. Another very important feature of magnets is that they all have a north pole and a south pole: unlike poles attract each other, whereas like poles repel each other.

Magnetic lines of flux

We can visualize the magnetic field – the invisible force that makes magnets behave the way they

do – as flux lines moving from the north pole to the south pole. Sometimes, the north and south

poles are not as easily identifiable as in the classic bar or horseshoe magnets. This is undoubtedly the case with electromagnetism.

2.      Electromagnetism

A magnetic field is created around an electrical conductor when an electric current is passed through it. This is known as electromagnetism, and the physical rules for ordinary magnetism also apply here. The magnetic field moves around the conductor. (See the fig. below)

The magnetic field around electrical conductors can be strengthened by winding them into a coil

around an iron core. When the wire is wound into a coil, all the flux lines produced by each turn of

the wire join up to form a single magnetic field around the coil. The greater the number of turns of the coil, the

greater the strength of the magnetic field. This field has the same characteristics as a natural magnetic field, and so also has a north and a south pole. 

3.       Electrical Motor construction -

Now let understand the electrical motor construction –

3a. Stator

The stationary electrical part of the motor. It contains a number of windings whose polarity is

changed all the time when an alternating current (AC) is applied. This makes the combined magnetic

field of the stator rotate.

3b. Rotor

Motors use so-called "squirrel cage" rotors, a name derived from their similarity to old-fashioned rodent exercise wheels. A current is produced when the stator's moving magnetic field cuts across the rotor conductor bars. This

current circulates through the bars and creates its own magnetic fields around each rotor bar. As the magnetic field in the stator keeps changing (because of applied AC current) , so does the field in the rotor. This interaction is what causes the rotor to move. (Check the below pics of the rotor)

3c. Rotation from magnetism

The advantage of having a magnetic field which is created by a current-carrying coil ( see the pics below)  is that it makes it possible to reverse the poles of the magnet by reversing the direction of the current. This ability to reverse the poles is precisely what we use to create mechanical energy. What follows is a brief look at how this works.

3d. Opposites attract -

Like poles repel each other while unlike poles attract. Simply put, this fact is used to generate constant movement of the rotor by continuously changing the polarity in the stator. You could think of the rotor as a magnet which is capable of rotating. This will keep the rotor moving in one direction, and the movement is transferred to the

motor shaft. In this way, magnetism is used to convert electrical energy into mechanical energy.

This evolution has been advanced to create induction motor technology used today by most industries worldwide.