(Image source: Generac)
An electric generator converts mechanical energy to electrical energy. So, how does a generator work? To answer the question fully, we need to start from the foundation. A generator, particularly the portable & home generator at the small size, consists of an engine, fuel source, a power generator head, and power outlets. The engine powers the generator head, the fuel source provide some fuel to the engine, either Liquid Propane, gasoline, diesel or natural gas.
Generator Engine Type
Irrespective of the kind of fuel used, all generators use a 4-cycle; OHV (overhead valve) type of engine, of variable horsepower. The engine provides the necessary mechanical energy to the generator head by rotating a shaft. A cooling mechanism and a means of lubrication are also included to reduce wear and tear on the moving parts. As the engine burns up the fuel, it thrusts a piston forth and back, pushing a generator head thereby converting mechanical energy into electrical energy. The electricity is then supplied to the power outlets. But what exactly goes on during the conversion? Read on.
How a generator Generates Electricity
- Conversion of mechanical to electrical energy: For a generator to generate electricity, it requires a magnetic field, a conductor to carry current, and relativistic motion between the magnetic field and the conductor. The generation of electricity is based on the principle of "Electromagnetic induction" (When there is a relative motion electric current will be induced (will flow)in the wire. Therefore, the mechanical energy possessed by the moving conductor is converted into the electric power of the current flowing in the wire.
- Electricity and Magnets: If you make electrons move in a metallic material, a magnetic field forms around the conductor. Similarly, if the spinning generator head rotates a magnetic field around coils of a conductor, electrons move to produce electricity. So, a generator typically rotates a permanent magnet around coils of copper wire creating steady flow electrons (and hence current!). A stationary armature, as opposed to a fixed magnetic field, is more beneficial because it is connected directly to the outlets. Once there is a steady flow of current, the remaining task is to harness the current and channel it to the outlets.
How to regulate the amount of current generated
1. One Pole pair
The magnitude of induced current depends on two things; the rotation speed of the generator head and the strength of the magnetic field. For a system with a pair of magnetic poles, each time the generator head makes one complete rotation, one AC cycle is produced. So, to generate a fixed frequency (50 or 60 Hertz), in synchronous generators, the magnetic field has to rotate at a fixed revolution per minute (RPM). A governor (a constant speed regulator) controls the rotation of the generator head under different conditions by varying the fuel feeding the engine.
2. Several Pole pairs
For a system with many pole pairs, whenever two adjacent poles (a North and South) pass one coil, the induced AC vary through one complete cycle. The frequency of output voltage for any given speed of rotation is given by the formula F=RPM X P/60, where P refers to the number of pole pairs. The analogy applies to conventional small home generators. Check a video simulation below for the appearance, connection and a graphic view of several pole pairs. The simulation puts to perspective the two scenarios above.
The electric energy is finally made available at the outlets of the portable generator for you to draw the types of which depend on the amp draw you want and the plug type at the receiving end of your appliances. Regardless of the kind, the outlets enable you to access electricity the way you're used to; through an electric plug. Higher output generators have a variety of outlet-type combinations.
Here are the NEMA receptacles, with their common US uses listed (in purple text)
Should read: How to hookup a portable generator to your house?
At the load
After the outlets, generated current continues flowing along the conductor until it comes across an electric load, for instance, a light bulb or toaster. The current, then, either creates light and heat, in the case of a light bulb or making a toast and proceeds on its way. The number of power a generator can provide is calculated by this formula: Watts = Volts x Amps. And if you choose the outlet at 120V, your generator running watt is 5000 Watts, then your generator is capable of providing total 41 amps. For more detail, you better read What Size Generator Do I Need
With a generator, and provided you have enough fuel, you can generate the electric power you need, anywhere anytime. You, therefore, should conserve the fuel since the moment you run out of it; your generator will stop generating electricity. Having answered the question how does a generator work comprehensively; you are now best positioned to reap heavily from the superb conveniences of electricity.