Difference between Alternator and Generator

In this article, we shall discuss the important differences between alternator and generator. The fundamental difference between an alternator and a generator is that an alternator is an electric generator which produces alternating current (AC) output, whereas the generator is an electromechanical energy conversion device which converts mechanical energy into electrical energy. Therefore, an alternator is also a type of electric generator.

Alternator

A type of electric generator which converts mechanical energy into AC electrical energy is called an alternator. Thus, the alternator is nothing but an AC generator. An alternator is basically a synchronous machine operated as a generator, i.e. input is mechanical energy.

The alternator has two parts namely, a rotating magnetic field system and an armature. When the magnetic field of the alternator is rotated by some external mean, it induces an alternating emf in the armature windings.

Alternators are widely used in electric power stations to produce electrical energy.

Generator

An electromechanical energy conversion machine that converts mechanical energy into electrical energy is referred to as a generator or an electric generator. An electric generator works on the principle of electromagnetic induction, i.e. when a conductor is moved in a magnetic field, an emf is induced in the conductor due to relative motion between the conductor and the magnetic field.

A generator consists of two main parts namely, an armature and a magnetic field system. An armature is a group of conductors in which the emf is induced by electromagnetic induction. The magnetic field system can be a set of permanent magnets or electromagnets. The field system produces the magnetic field inside the generator required to generate emf.

Difference between Generator and Alternator

The important differences between the alternator and generator are listed in the following table:

Alternator	Generator
An electrical machine that converts mechanical energy into AC electrical energy is called an alternator.	An electrical machine that converts mechanical energy into electrical energy is called a generator.
The alternator is also known as an AC generator or synchronous generator.	The generator is also known as an electric generator.
All the alternators are types of electric generators.	It is not necessary that all the generators are alternators.
The alternator always supplies alternating current to the load.	The generator can supply either alternating current or direct current.
Alternators are of two types namely, salient-pole alternators and cylindrical-rotor alternators.	Generators are of two types namely, AC generators and DC generators.
The alternator cannot be used to charge a battery.	A DC generator can be used to charge a battery.
The alternator always has a stationary armature.	Generators can have either stationary armature (ac generator) or rotating armature (dc generator).
The alternator always generates an alternating emf.	Generators can produce either alternating emf or constant emf.
The alternator always has a rotating magnetic field.	Generators can have either a rotating magnetic field or a stationary magnetic field.
The alternator does not have a commutator.	Generator (dc generator) has a commutator.
Alternators are widely used in power generating stations, industries, automobiles to charge batteries, etc.	Generators are used to generate electrical energy.

Hence, all these are the important differences between alternator and generator.