Terminology

The two main parts of a generator or motor can be described in either mechanical or electrical terms[citation needed]:
Mechanical:
Rotor: The rotating part of an alternator, generator, dynamo or motor.
Stator: The stationary part of an alternator, generator, dynamo or motor.
Electrical:
Armature: The power-producing component of an alternator, generator, dynamo or motor. In a generator, alternator, or dynamo the armature windings generate the electrical current. The armature can be on either the rotor or the stator.
Field: The magnetic field component of an alternator, generator, dynamo or motor. The magnetic field of the dynamo or alternator can be provided by either electromagnets or permanent magnets mounted on either the rotor or the stator. (For a more technical discussion, refer to the Field coil article.)
Because power transferred into the field circuit is much less than in the armature circuit, AC generators nearly always have the field winding on the rotor and the stator as the armature winding. Only a small amount of field current must be transferred to the moving rotor, using slip rings. Direct current machines necessarily have the commutator on the rotating shaft, so the armature winding is on the rotor of the machine.

MHD generator

A magnetohydrodynamic generator directly extracts electric power from moving hot gases through a magnetic field, without the use of rotating electromagnetic machinery. MHD generators were originally developed because the output of a plasma MHD generator is a flame, well able to heat the boilers of a steam power plant. The first practical design was the AVCO Mk. 25, developed in 1965. The U.S. government funded substantial development, culminating in a 25MW demonstration plant in 1987. In the Soviet Union from 1972 until the late 1980s, the MHD plant U 25 was in regular commercial operation on the Moscow power system with a rating of 25 MW, the largest MHD plant rating in the world at that time. [1] MHD generators operated as a topping cycle are currently (2007) less efficient than combined-cycle gas turbines.

Other rotating electromagnetic generators

Without a commutator, the dynamo is an example of an alternator, which is a synchronous singly-fed generator. With an electromechanical commutator, the dynamo is a classical direct current (DC) generator. The alternator must always operate at a constant speed that is precisely synchronized to the electrical frequency of the power grid for non-destructive operation. The DC generator can operate at any speed within mechanical limits but always outputs a direct current waveform.
Other types of generators, such as the asynchronous or induction singly-fed generator, the doubly-fed generator, or the brushless wound-rotor doubly-fed generator, do not incorporate permanent magnets or field windings (i.e, electromagnets) that establish a constant magnetic field, and as a result, are seeing success in variable speed constant frequency applications, such as wind turbines or other renewable energy technologies.
The full output performance of any generator can be optimized with electronic control but only the doubly-fed generators or the brushless wound-rotor doubly-fed generator incorporate electronic control with power ratings that are substantially less than the power output of the generator under control, which by itself offer cost, reliability and efficiency benefits.

Historic developments

Before the connection between magnetism and electricity was discovered, electrostatic generators were invented that used electrostatic principles. These generated very high voltages and low currents. They operated by using moving electrically charged belts, plates and disks to carry charge to a high potential electrode. The charge was generated using either of two mechanisms:
Electrostatic induction
The triboelectric effect, where the contact between two insulators leaves them charged.
Because of their inefficiency and the difficulty of insulating machines producing very high voltages, electrostatic generators had low power ratings and were never used for generation of commercially-significant quantities of electric power. The Wimshurst machine and Van de Graaff generator are examples of these machines that have survived.

Generators Types and Features

We recommend diesel due to their longevity and lower operating costs;1. 1800 rpm water cooled diesel operate on average 20-30,000 hours before major engine maintenance is required.2. 1800 rpm water cooled gas normally operate 6-10,000 hours because they are built on a lighter duty gasoline engine block.3. 3600 rpm air-cooled gas engines are normally replaced – not overhauled at 500 to 1500 hours. Because gas engines burn hotter (higher btu of the fuel), you will see significantly shorter lives. Our gensets are from the world’s top manufacturers. We offer products for high-end residential customers with larger homes to industrial and military customers seeking prime power or critical emergency backup generators.Electric equipment is designed to use power with a fixed frequency: 60 Hertz (Hz) in the United States and Canada, 50 Hertz in Europe and Australia. The frequency output depends upon a fixed engine speed. To produce 60 Hz electricity, most diesel engines operate at 1800 or 3600 RPM. Each speed has its advantages and drawbacks. At 1800 RPM, four pole electric power sets are the most common and least expensive. They offer the best balance of noise, efficiency, cost, and engine life. At 3600 RPM, two pole generators are smaller and lightweight; they are best suited for portable, light-duty applications. In simple terms it’s like operating your car at 90 mph, versus 45mph — at 45mph your car will last longer; it is quieter, requires less maintenance, and has a longer life. Most 3600 rpm gensets are twin cylinder air-cooled lawn mower engines, while the water cooled 1800 rpm units are comparable to those found in diesel forklift and diesel tractor engines. The 1800 rpm water cooled engine will last longe r, offerless maintenance problems, and be more fuel efficient. We recommend diesel! Gensetcentral Systems can provide for all your backup power needs from 2 Mega Watt generator for industrial, residential and military applications. We can provide you with high quality gensets. We offer only top quality products that are priced at or below our competition who offer lesser brands Our diesel products are powered by world class diesel engines - we feature SDMO, Lister Petter, Katolight, Baldor, Kubota, John Deere and Cummins power plants

Human powered electrical generators

Main article: Self-powered equipment
A generator can also be driven by human muscle power (for instance, in field radio station equipment).
Human powered direct current generators are commercially available, and have been the project of some DIY enthusiasts. Typically operated by means of pedal power, a converted bicycle trainer, or a foot pump, such generators can be practically used to charge batteries, and in some cases are designed with an integral inverter. The average adult could generate about 125-200 watts on a pedal powered generator. Portable radio receivers with a crank are made to reduce battery purchase requirements, see clockwork radio.

How Generators Work