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Electric Motor – Definition, Elements, Fundamentals, and More

Electric Motor Definition

An electric motor is an electrical machine that transforms electrical energy into mechanical energy through variable magnetic fields. Electric motors are made up of two parts, a fixed one called a stator and a mobile one called a rotor.

These generally work under the principles of magnetism, which are developed within the research. In addition to this, the classification of the same will be specified, which would be Direct Current, Alternating Current.

And Universal Motors and according to the number of phases in Single-phase, Two-phase and Three-phase, the latter being the most widely used at an industrial level.

Elements of Electric Motor

electric motor

  • Electric motors are made up of several elements, which are defined in the content of this research. However, the main parts are the stator, the casing, the base, the rotor, the connection box, the covers and bearings. However, a motor can run only with the stator and rotor.
  • On the other hand, the primary connections with which it is possible to power the electric motors are explained, detailing each of them and the advantages they usually provide.
  • It also emphasizes a significant issue for the conservation of electric motors, such as their preventive maintenance,
  • The lengthening of the motor’s useful life and reducing losses and deformations thereof investigate, concluding the investigation with a series of recommendations for the installation and maintenance of electric motors.

Fundamentals of Operation of Electric Motors

  • In magnetism, two poles are known: the north pole (N) and the south pole (S), the regions where the lines of force of a magnet concentrate. A motor to function uses the forces of attraction and repulsion that exist between the poles.
  • Accordingly, every motor has to form with alternating poles between the stator and the rotor, since like magnetic poles repel, different magnetic poles attract, thus producing rotational motion. The figure shows how the rotational movement occurs in an electric motor.
  • An electric motor operates primarily based on two principles: Induction, discovered by Michael Faraday in 1831, which points out that a conductor moves through a magnetic field.
  • It is located in the vicinity of another conductor through which a current of varying intensity flows. An electric current induces the first conductor.
  • And the principle that André Ampére observed in 1820, in which he establishes: that if a current passes through a conductor located inside a magnetic field, it exerts a mechanical force or emf (electromotive force) on the conductor.

Fundamental Parts of an Electric Motor

electric motor

Among the fundamental characteristics of electric motors, they make up of several elements. However, the main parts are the stator, the casing, the base, the rotor, the connection box, the covers and the bearings. However, a motor can run only with the stator and rotor.


The stator is the element that operates as a base, allowing the rotation of the motor to take place from that point. The stator does not move mechanically, but it does move magnetically. There are two types of stators

  1. a) Salient pole stator.
  2. b) Grooved stator.

The stator is mainly made up of a set of silicon steel sheets (and they call a “package”).

It can allow the magnetic flux to pass through them with ease; the stator’s metal part and the windings provide the magnetic poles.

The poles of a motor are always pairs (they can be 2, 4, 6, 8, 10, etc.); therefore, the minimum number of poles that a motor can have to operate is two (one north and one south).


The rotor is the mechanical transfer element since the conversion of electrical to mechanical energy depends on it. Rotors are a set of silicon steel sheets that form a package and can be basically of three types:

  1. a) Slotted rotor
  2. b) Salient pole rotor
  3. c) Squirrel cage rotor

Types and Characteristics of Electric Motors

The DC motors [CD] or direct current [DC .]:

They use in cases where it is crucial to continuously regulate the engine’s speed, also used in cases where it is essential to use direct current, as is the case of motors powered by cells or batteries.

This type of motor must have the same number of poles and the same number of carbons in the rotor and stator.

1. Case

The casing is the part that protects and covers the stator and rotor. The material used for its manufacture depends on the type of motor, its design and its application. Thus, the casing can be:

  1. a) Fully closed
  2. b) Open
  3. c) Drip-proof
  4. d) Explosion-proof
  5. e) Submersible type

2. Base

The base is the element where all the mechanical operating force of the engine support. It can be of two types:

  1. a) Front base
  2. b) Lateral base

3. Connections Box

  • In general, in most cases, electric motors have a junction box.
  • The connection box is an element that protects the conductors that feed the engine, protecting them from the mechanical operation of the motor and against any piece that could damage them.

4. Tapas

  • They are the elements that will support the vast majority of cases the bearings that support the action of the rotor.

5. Bearings

Also known as bearings, they contribute to the optimal operation of the rotating parts of the motor. They use to support and secure mechanical shafts and reduce friction, reducing power consumption. Bearings can divide into two general classes:

a) Sleeve bearings: They operate the base at the beginning of the oil film. That is that there is a thin layer of lubricant between the axle bar and the bearing surface.

b) Rolling bearings: They use in preference to sleeve bearings for several reasons:

  • They have a lower coefficient of friction, especially at startup.
  • They are compact in design
  • And also, they have high operating precision.
  • They do not wear as much as slide-type bearings.
  • And also, they easily replace due to their standard sizes.


An electric motor is an electrical machine that transforms electrical energy into mechanical energy through electromagnetic interactions.

Some of the electric motors are reversible. They can transform mechanical energy into electrical energy by working as generators. Electric traction motors used in locomotives often perform both tasks if equipped with regenerative brakes.

They widely used in industrial, commercial and private facilities. They can work connected to a  power supply network or batteries. Thus, in cars, they are beginning to use hybrid vehicles to take advantage of both.

Also Read: Gases – Definition, Examples, List of the Elements, and More

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