A portable generator consist of basically an engine, a power generator head, power outlets and a fuel source. They are sometimes known as an engine-generator set, or gen-set by some people for this reason. The component which makes the electricity which supplies the power outlets is the generator head. The generator head is run by the engine and it has to be supplied by some kind of fuel, which is usually liquid propane, gasoline, diesel or natural gas.
No matter what kind is used, typically a 4-cycle engine, overhead valve kind of varying horsepower will give the needed mechanical energy to the generator head by way of spinning a shaft. A governor, or constant speed regulator, controls how fast the spin is. There also needs to be a system for cooling and a method of lubrication the moving parts. The mechanical energy is then converted to electrical energy by the generator head, and gives the power outlets electricity.
A generator moves a magnet close to a wire to make a flow of electrons that is steady. In a typical generator, the engine turns the generator head at a RPM which is measure. Copper wire, magnets and electrons moving inside makes electricity. Each rotation of the engine makes one sine wave of AC power. For the electricity to make a standard 120 volt, the engine has to be running at a constant speed of 3,6000 RPM.
The magnet inside a generator pushes a particular amount of electrons along and puts a certain amount of pressure to the electrons. The number of electrons in motion in an electrical circuit is called the current, or amperage, and is measured in amps. The voltage is the pressure pushing the electrons and is measured in volts. The amount of electrons moving is an amp and the pressure behind those electrons is the voltage.
The electrons which are moving through the wire keeps going until it encounters a load such as an appliance or light bulb, then creates either light or heat in a light bulb and goes on its way.
You then have electrical power available that can be drawn from the outlets on a portable generator. The types of outlets depend upon the type of plug and the amp draw with you would like at the receiving end for your devices.
You can access the electricity the way you are used to from the power outlet by plugging in a cord. Since some people want a portable generator for power to devices different than your regular three prong wall outlets would, the supply of electricity is available through various outlets. The more power the generator, in general, the more combinations of outlets you will have.
All portable generators of course have the regular three prong outlet like you see on your walls. These give you 120 volts and 15 or 20 amps.
The heftier plugs with various prong holes are useful for more than just powering your high powered equipment. A lot of them can give you 30 amps, so a lot of people use a cord which fits the outlet, then spits into three or more regular three-prong outlets so you have better versatility where the 30 amps can be divided up between devices.