how does a portable generator work unspecified 1500W portable generatorThe Simple Basics

So how does a portable generator work? Well it’s best to start at the beginning.  A Portable Generator basically consists of a power generator head, an engine, a fuel source and power outlets.  For this reason, they are sometimes known as an engine-generator set, or a gen-set by some people. That description is its simplest form and an explanation of how they work separately and together follows.

The generator head is the component that produces the electricity that supplies the power outlets.  The engine runs the generator head and the engine must be supplied by some sort of fuel, usually gasoline, liquid propane, natural gas or diesel.

Regardless of the type of fuel used, an engine, usually a 4-cycle, overhead valve type of varying horsepower will provide the mechanical energy necessary to the generator head by spinning a shaft.  A constant speed regulaor (governor) controls the speed of the spin.  There must also be a cooling system and method of lubrication of the moving parts.  The generator head then converts the mechanical energy to electrical energy and supplies the electricity to the power outlets.  An inverter type generator works a bit differently.  But just how does a generator provide electricity?

How Does a Portable Generator Work

Electricity and Magnetism

How does a portable generator work magnetOK here’s the simple version.  I’m no physics professor, or even an electrician.  You often hear the words electricity and magnetism together.  In fact that was the name of my physics class in college.  So they are related.  Do you remember taking a magnet as a kid and picking up pins and paper clips and other metal things?

Well what’s happening here is there are electrons in the metal material that are moved by the magnet.  Similarly, if you can cause electrons to move in a metal wire, a magnetic field will form around the wire.  So if that spinning shaft in an engine-generator can rotate a magnetic field around coils of copper wire, electrons are moved to produce electricity.  Pretty cool huh?

Well a generator simply moves a magnet near a wire to create a steady flow of electrons.  This is the simplest form.  Harness this flow of electrons and direct it to the outlets and you have your generator.  Sound simple?  Well it’s a little more complicated than that.

In a conventional generator, the engine rotates the generator head at a measured RPM.  This movement of magnets, copper wire and consequently electrons, produces electricity.  Each engine rotation produces one sine wave of AC powerFor a better explanation of what AC power is, refer to the article on this site. For the electricity to produce the standard 120-volt, 60-Hz electricity we commonly use in the US, the engine must run at a constant speed of 3,600 RPM.

In Simpler Terms – the Water Hose Analogy

water hose analogyOK you say, what’s all this about Volts, Amps and the Watts that the generators are rated by?  Well think of a flow of water being sent through a water hose.  Think of the generator as a water pump pushing the water through the hose, only instead of pushing water, a generator uses a magnet to push electrons along. Just like a water pump pushes a certain number of water molecules and applies a certain amount of pressure to them, the magnet in a generator pushes a certain number of electrons along and applies a certain amount of “pressure” to the electrons.

In an electrical circuit, the number of electrons in motion (the water) is called the amperage or current, and it’s measured in amps. The “pressure” pushing the electrons along is called the voltage and is measured in volts.  An amp is the number of electrons moving and the voltage is the amount of pressure behind those electrons.

One amp physically means that 6.24 x 10 exponent18 electrons move through a wire every second.  If you don’t know what “1018”  means, it means there are 6,240,000,000,000,000,000 electrons moving through the wire every second.  That’s a LOT of electrons!  I don’t even know if that many zero’s has a name!

These electrons moving through the wire continues along until it encounters a “load” like a light bulb or appliance, does it’s thing by either creating heat and light in a light bulb or making your toast, and continues on its way.

Higher output portable generators may have dual 120 volt/240 volt capability.  240 volts over the standard 120 volts meaning that there is twice the pressure pushing the water in the hose, or even more electrons available at the other end for work

The Outlets – Why So Many Configurations

How Does a Portable Generator work - NEMA outlet chartThis electrical power is then available to draw from the outlets on the portable generator.  These outlet types depend on the plug type and the amp draw that you want at the receiving end for your electrical device(s).  On this site, check out the article for a quick view of various outlets found on portable generators.

The power outlets allow you to access the electricity the way we’re used to – by plugging in a cord.  Since there are users who want a portable generator to supply power to different devices than just your standard three prong wall outlets would, the electrical supply is available through a variety of outlets.  In general, the more powerful the generator, the more outlet combinations are available.

Of course all portable generators have the standard three prong outlet like we’re used to seeing on our walls.  These providing the 120 volts and either 15 or 20 amps.

The beefier plugs with the different “prong holes” are more useful than simply for powering your high powered equipment.  Since many of these can provide 30 amps, many people use a cord that fits the outlet then splits into 3 or more standard three-prong outlets for more versatility where the 30 amps can be shared among more devices.  Visit the article on this site for more information on extension cords.

How Does a Portable Generator work -Westinghouse extension cord

A locking 4 prong 30 amp at the plug end with four 3 prong 20 amp receptacles at the other

What Do Watts Mean?

Portable generators are then rated by the amount of power they produce called watts. As the wattage increases, everything else increases as well.  More versatility in voltage and outlets.  Bigger engine, HP, fuel tank, weight, noise level and cost.

The basic formula as it relates to available power is watts = amps x volts.  If you have a 4000 watt generator, and you know they always provide 120 volts, then you know you can serve a total of 33 amps.  That’s how you determine how much you can power with the wattage generator you have.  For information on how to determine what size generator you’ll need, read the article on this site, “What size portable generator do I need?”

Look through the site for other useful articles to help you decide what portable generator is right for you and especially how to safely operate one.

Filed under: How It Works