The term “generator” is used in broad sense for item that generates something, but here our main concern is with an equipment used for generating electricity or device that converts mechanical energy into electrical power for use in an external circuit. It may be a small powerhouse that can be used in home or any building for off grid power or a gigantic equipment to use in power generation house for distribution of electricity on a large scale. The source of mechanical energy may be water turbine, gas turbine, steam turbine, internal combustion engine or even hand cranks. Power grid generators have enormous power generating capacity.
Mechanically, a generator has two core parts: stationery part and rotating part. The stationery part consists of stator that surrounds rotor, the rotating part of the equipment. An electric current is induced by varying magnetic field in the wire winding in one part, the part continues to generate a magnetic field. Permanent magnets, also called field magnets or field winding are field producing components of this equipment. Either permanent magnets or wire windings called field coils provide the magnetic field of the dynamo or alternator. Electric current for providing power to an external circuit is generated by the armature windings in this equipment.
There are two main categories of this equipment: Direct Current (DC) or Alternate Current (AC). A generator has different genre and every category is a specialized type. Dynamos are class of direct current (DC) generators that produce direct current as a power source. DC generators include homopolar generators and magnetohydrodynamic (MHD) generators. AC generators include induction generators, linear electric generator, and Variable-speed constant-frequency generators.
A generator is used for multiple common and large-scale commercial applications. This equipment is used in common bicycles, sailboats, and roadway vehicles. Its use is common for home power generation and power generation for large-scale distribution.