How Do Electrical Generators Work?

Posted on: 20 June 2017


Firstly, it is important to note that electrical generators do not create electricity as such. Rather, they convert mechanical energy into an electrical charge via the wires present in its windings. A diesel-powered electrical generator manufactured today functions on exactly the same principles of electromagnetic induction that were first noted in the 1830s by the British scientist, Michael Faraday.

Specialists in electric motor repair should be sought out if you have one with a problem. A generator repair ought to be undertaken by a professionally trained operative only. The following is a guide to the basic principles behind generators' functions, not a guide to rewinding and repairs or maintenance.


Generator engines are the part of the system that creates the input force needed to produce electricity. Most are powered by diesel these days, but you can also find ones that will run on petrol and even propane, in some cases. This is the part of the system that makes the most noise when operating, but modern designs have become more and more focussed on quieter engines.


Also referred to as generator heads, alternators produce an electrical output from the mechanical energy being created by the engine. An alternator contains an assembly of both moving and stationary components and is commonly encased in a protective housing. Like other parts of a generator, alternator repairs are best conducted by experts because all the parts must be correctly aligned to avoid problems. Essentially, the parts of an alternator work together to cause relative movement between the magnetic fields involved. In turn, this generates an electrical current. Think of them as offering the inverse function of an electrical motor.

Voltage Regulators

As you might expect from its name, a voltage regulator does nothing more than to regulate the output voltage that is coming from the generator. This device is able to convert alternating current (AC) to direct current (DC) or vice versa, depending on the application. Since most commercially available generators are used with conventional electrical products, they tend to output usable AC voltage. So-called exciter and armature windings in a voltage regulator produce this form of electricity.


In order to start the electromagnetic field that is needed for an alternator to work, an electrical system is needed to help the generator get going. Therefore, most have an internal battery system which will create the necessary field to get the system ready for its input from the engine. Once started, no further use of the battery is required and it will usually trickle charge, making it ready to be used the next time the generator is fired up.