Electrical machines are devices that transforms mechanical energy into electrical energy and vice versa. Generators and motors are the two main pieces of equipment in electrical machines. Generators are the devices that deliver electrical energy through a mechanical system while motors are the devices that deliver mechanical energy from an electrical system.


Electrical machine’s working depends on the following set of principles:

  1. Faraday’s Law of Electromagnetic Induction

It describes the relation between emf and magnetic field. When a conductor is placed in contact with a varying magnetic field, an emf is induced in the wire.

  1. Mutual Induction

A conductor having an alternating current in it will produce a magnetic field around it. Similarly, if another conductor comes in contact with that magnetic field, an emf will be induced in the second conductor.

  1. Lenz’s Law of Electromagnetic Induction

After the emf induction, the direction of induced emf is decided by the fact that it should oppose the cause of its production.

Types of Electrical Machines

  1. Generators

A generator is a machine that converts mechanical energy into electrical energy by rotating a coil in the presence of permanent magnets that are placed around the coil. In view of the Faraday’s law of induction, an emf will be induced in the coil. This is how rotating (mechanical energy) is converted to induce emf (electrical energy).

The coil which contains the induced emf is known as armature winding, while the coil that has permanent magnets in it is known as field winding. In addition to these coils, there are also a number of components that a generator has in order to transfer the produced electrical energy easily. As these devices are one of the oldest inventions there are a number of electrical machinery manufacturing companies that provide good quality machines for homely usage.

There are two categories of generators; one for the alternating current and the other one is for direct current.

  1. Motors

A motor is a machine that converts electrical energy into mechanical energy by placing a current carrying conductor in a magnetic field and it experiences a force. Its construction is very similar to that of a generator, but the working principle is different. When the current carrying coil placed in between varying magnetic field, a force is experienced by the first coil that makes the coil to rotate.

Motors are available both for alternating current and the direct current.

  1. Transformer

This device is a new addition to the electrical machine’s family. A transformer is a device that is not responsible for energies conversion but is used for leveling up and leveling down the induced emf. This device purely works on the principle of mutual induction.

The transformer is only applicable in case of alternating current because, in case of direct current, there would be an induction in the coil and if we use it for direct current, the core windings will burn out causing serious damage to the machine.