How Do Generators Work?

Anyone who has experienced a power outage knows how useful generators can be to keep home lighting and appliances running or business equipment operational. Generators can be used for backup power during outages or as temporary power where electricity isn’t available, such as a campsite or temporary worksite. They burn fuel to produce electrical energy to power devices that only run on electricity.

An electric generator is an appliance that uses mechanical energy to produce electrical charges and move them through an electric current. Its engine creates mechanical energy which is pushed through an electrical conductor in a magnetic field, creating electric charges and generating electric current.

A generator has various components, including an engine, an alternator, a fuel system, a voltage regulator, cooling and exhaust systems, a lubrication system, a battery charger, a control panel, and a frame or main structure.


The generator’s engine is what creates mechanical energy. Generators come with various sizes of engines, and the size of the engine determines how much electricity it can produce. Generator engines operate on various fuels, such as gasoline, diesel, liquid or gaseous propane, and natural gas. Some generator engines operate on a dual feed of diesel and gas.

Generator engines are either overhead valve engines or non-overhead valve engines. Overhead valve engines have the intake and exhaust valves in the head of the engine’s cylinder instead of mounted on the engine block, and are usually more expensive than non-overhead valve engines. They are smaller, easier to use, last longer, and have lower noise and emission levels during operations.

Cast Iron Sleeve in the engine cylinder is a desirable feature to look for when buying a generator. It’s a lining in the cylinder of the engine that reduces wear and tear, ensures durability, and is important to the length of operational life especially for generators that are used on a regular basis.


The alternator is the part of the generator that produces electrical output to generate electricity. Its stator and rotor are surrounded by a housing unit that encloses the operation. The housing can be metal or plastic, but metal is preferable because it’s less susceptible to damage that may expose moving parts. Alternators can have ball bearings or needle bearings, but ball bearings last longer. An alternator with a brushless design will produce cleaner power and need less maintenance.

Fuel System

Generator fuel systems include a pipe connection from the fuel tank to the engine, a ventilation pipe, an overflow connection from the fuel tank to the drain pipe, a fuel pump, a fuel filter, and a fuel injector. Larger commercial generators may use external fuel tanks, while small generators have fuel tanks either mounted on top of the unit or as part of the base.

Control Panel

The generator control panel is where the generator is turned on and monitored during operation. It includes an electric start and shut-down, with some generators providing automatic operation during power outages. The control panel also has engine gauges to monitor oil pressure, coolant temperature, and battery voltage.

There are portable generators, residential standby generators, and commercial standby or industrial generators. Different types of generators have different operating applications. Portable generators may use extension cords to power small appliances, while other generators may have a power transfer switch connected to the main electrical panel for direct transfer of electricity without cords. The type of generator to use depends on the application, residential or commercial, and the amount of electrical output required, a little for a short or temporary time, or a large amount for an extended period of time.