The 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
OK 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 block wave of AC power. For 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
OK 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
This 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.
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, horsepower (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
Hi. I recently I bought a chinese 5000w portable Inverter gasoline generator. It is only 120v. My question is: Can I change any component in orden to change it to 220v? I a asking because I don’t know what make it produce the 120v, the generator head or the inverter panel ( called Black box). It is very dificult to get answers even by googling them.
Thanks in avance .
I have heard of rewiring the hot leads from the 120’s to make a 240 outlet. You would start with the electrical diagram of your unit and an electrical diagram of a 120/240 model. I wouldn’t attempt it because of possible warranty issues, but more importantly, because I just don’t know enough. There are some discussion forums, but I didn’t find one on an inverter. I wish I could be more help, but I know when my knowledge is limited and I don’t want to steer you in the wrong direction. Good luck.
Thanks for your answering ray. I know the rewiring trick in conventional genset.
Here are the output voltage my inverter genset is capable of according with factory specs:
Rated AC Voltage 110/220/230/240V.
This genset has no dual voltage outlets ( 110V and 220V like the Honda ). This china inverter generators come either 110V or 220V. My question is how the factory makes them produce 110v or 220V. I think it is the inverter module that does that convertion since the generator head is capable of producing 3 phase voltages ranging around 400V AC I think.
I know when I don’t know something. The workings of an inverter module is beyond my knowledge. I wish I could provide you with the answer. Perhaps one of our readers can provide some insight. Good luck Alexis.
Hello. I have just bought a New Holland portable generator AC-7500H. It suppose to bring 110/220/380v and 7500 kw.
It has 4 plugs; 2x110v, 1x220v and 1x380v. I am using this generator with only 110v appliances, since in Mexico 110v is the standard.
My questin is: There is a little “switch (trigger)” that says 110v (left) 220v (right) near the circuit breaker. Do you know how does it works and what for?
I guess it works to “transform” all de outputs to 110v that would be awsome so i can plug 4 extensions of 1800 watts (that are easier to buy here).
Thanks.
Hello Roberto,
I am not familiar with you generator, but I can guess that you have the standard plugs (2) and a plug the has a circular shape with holes for larger plug in. The larger plug is the one than can provide the larger voltage amounts. If you plan to only use 110V receptacles, you can either use the 2 x 110V or you can use the larger one with a cord that can provide multiple standard plugs at the other end. The switch that you mention will be turned to the right (220V) when you use the larger cord. By only using the 110V plugs you may be limited from using your full generator’s potential. (I think your generator has 7500 W and not 7500 kw)
Hope this helps,
Ray
hello ray bolger
i just wanted to let you know that you are such a sweet soul
me and my 4 kitty kats love to hop in and see what you have to say to others. i myself have a portable generator and this page has helped me a lot. since i have a lot of power outages where i live (in wales) power generators are my best friend (next to Mr. Chinky my baby kitty kat).
anyways thank you for keeping me and Mr. Chinky entertained.
xoxo,
Your Welsh Madam Mercredi
You are so kind Madam Mercredi. I am glad that you enjoy my words. I enjoy helping where I can. My best to you and Mr. Chinky. Stay safe.
Ray
I have always wondered how a generator worked. Thank you for the information about generators. I didn’t know that a generator simply moves a magnet near a wire to create a flow of electrons. That does sound really simple!
i have a KlutchST200iDV Dual Voltage Inverter-Powered Stick/TIG Welder — 120V/230V, 15–200 Amp and i was wondering if i could use Cat INV2000-1800 Running Watts/2250 Starting Watts Gas Powered Inverter Generator 522-2700
Hi Josue,
I wish I could help you, but I don’t know enough about the power requirements for your device. I suggest you might contact the manufacturer of your Welder and ask them the minimum requirements of a generator for your purpose.
Good luck,
Ray
I’m comparing generators and hope to get a quick response. Do I need to get a 120/240V generator if I ultimately want someone to hook up to my electrical box? I will mainly run lights, ceiling fan, refrigerator and freezer. If 120V is ok, I’m comparing Champions: 76533, 46539, 100554. Can you share insight on these?
THANK YOU!!
Hi Cindy,
Most electrical box connections will require a 240V unit. That said, if you indeed only want to run the some lights, a fan and your refrigerator/freezer (I presume in an outage), you may be able to run extension cords with a 120V unit. Champion makes good, reliable generators. 4000 – 5000 watts would be ample. You could get less, but you will be glad you have extra available power if necessary.
You may not be able to run your ceiling fan this way, but a portable plug in fan will work. Good luck and stay safe.
Ray.
Hi, Ray. I’ve been “gleaning” info all over your site. The electricity basics article has been particularly rewarding, since I but have never been clear on the relationship of the different current-related terms. I purchased a Generac GP5500 late last fall, only had to use it for about four hours. I’m interested in replacing the haphazard collection of cords with a more planned distribution of power. I think the wording in the manual says that each of the two 5-25R duplex receptacles will handle 2400 watts, for a total of 4800 watts for both duplexes. The
120/240 L14-30 will handle 7200 watts when operating on 240. I don’t see a selection switch. Does the generator change to 240 automatically when the demand exceeds the maximum on 120? My confusion is probably due to my remaining lack of understanding of volts/amps/watts. Thanks for any help.