Electric Motor – Definition, Construction, and Working

Electric motor is a most widely used electrical machine in a wide range of applications from domestic to industrial. It is a type of electromechanical energy conversion device that transforms electrical energy into mechanical energy. The principle of electromechanical energy conversion was given by Michael Faraday in 1821.

This article is meant for explaining the basics of electric motor, such as definition, construction, working, types, etc. So, let’s get started with the basic introduction to electric motor.

What is an Electric Motor?

An electromechanical energy conversion device that transforms electrical energy into mechanical energy is called an electric motor.

Therefore, an electric motor takes electricity as the input and produces mechanical energy in the form of rotation of shaft as the output.

The block diagram of an electric motor is depicted in the following figure.

An electric motor is one of simplest mean for producing mechanical power from electrical power.

Electric motors are commonly used to drive mechanical loads like fans, pumps, compressors, conveyors, lifts, cranes, air conditioners, and more.

Construction of Electric Motor

In actual practice, we have different types of electric motors having different constructions. But all the electric motors have the same fundamental structure.

A typical electric motor has two essential parts namely, stator and rotor.

The stator is a stationary or non-moving part of the motor. While, the rotor is a moving or rotating part of the motor.

The stator has a winding called stator winding. The stator also provides the mechanical covering and protection against mechanical threats to the internal parts of the motor. The stator of an electric motor is basically a hollow cylinder made up of cast iron.

The rotor of the electric motor is a moving part having a rotor core, rotor winding, and a mechanical shaft. The rotor core is a cylindrical piece of steel provides housing to the rotor winding. The rotor core is mounted on the shaft and a mechanical load is attached to the motor shaft.

Apart from stator and rotor, an electric motor also has some auxiliary parts such as bearings to reduce friction between moving and stationary parts, cooling fans to balance the temperature of the motor, etc.

Let us now understand how does an electric motor work.

Working of Electric Motor

An electric motor works on the principle of electromechanical energy conversion through electromagnetic induction.

In an electric motor, there are two windings namely, field winding and armature winding. The placement of these windings depends on type of design of the motor. For example, in an induction motor the field winding is placed on stator, while in a synchronous motor, the field winding is placed on the rotor. But the functions of these two windings remain the same in all types of motors.

The field winding produces the working magnetic flux in the motor while the armature winding develops the torque required to drive the mechanical load connected to the shaft.

When electrical energy is input to the electric motor, a magnetic field is produced in the air gap between the stator and rotor. This magnetic field cuts the armature winding and induces an emf and a current in the armature winding through the electromagnetic induction. Due to current in the armature winding, a magnetic flux is produced.

Now, there are two magnetic fields inside the motor namely, main field and armature field. These two magnetic fields interact with each other and produces a torque that rotates the rotor.

This is how an electric motor works when an electrical input is given to it.

Classification of Electric Motors

Electric motors are broadly classified into the following two types −

DC Motor

An electric motor that takes direct current electricity to work and produce mechanical energy output is called a DC motor or direct current motor.

AC Motor

An electric motor that requires alternating current electric supply to operate and produce mechanical energy output is called an AC motor or alternating current motor.

Advantages of Electric Motors

Electric motors offer several advantages over other methods of producing mechanical energy to drive mechanical loads. Some key benefits of using electric motors are given below −

• Initial and operation costs of electric motors are low.

• Electric motors have relatively longer lifespan.

• Electric motors require less maintenance.

• Electric motors provide easy start and stop and efficient speed control.

• Electric motors have less noisy operation.

• The energy conversion efficiency of electric motors is relatively high.

Applications of Electric Motors

Electric motors are widely used in several domestic, commercial, and industrial applications. Some common applications of electric motors are given below −

• Electric motors are used to run domestic appliances such as fans, air conditioners, refrigerator, water pump, etc.

• Electric motors are also used in printers, printing presses, computers, etc.

• Electric motors are also used in automobiles and electric vehicles.

• Electric motors are used to drive machinery in industries, etc.

Conclusion

In conclusion, electric motor is an essential electrical machine used to convert electrical energy into mechanical energy. A typical electric motor consists of two major parts namely stator and rotor. The working of an electric motor is based on the principle of electromechanical energy conversion through the electromagnetic induction. Electric motors are widely used in various applications like in fans, refrigerators, conveyors, crushers, electric vehicles, and more. In this detailed article on electric motor, I have explained the definition, construction, and working of electric motor.