Generator

A generator is a machine that converts mechanical energy into electrical energy by rotating an armature, which contains conductors, through a magnetic field. A voltage is induced in the moving conductors by an effect called electromagnetic induction. In order for voltage to be generated, relative motion must exist between the conductors and the magnetic field. An engine, motor, turbine or other source of mechanical energy is used to turn the armature shaft. Generators are built in many sizes. Most electricity used today in cars, in homes and by industry in producing things by generators.

The two main types of generators are direct-current (DC) generators and alternating-current (AC) generators. The DC generators rotates the conductors in a stationary magnetic field. The AC generators (alternator) rotates a magnetic field that is cut by the stationary conductors. Current induced in the conductors of all generators is an alternating-current. The current taken from the generator for the electrical load circuit, however, may be either AC or DC, depending on how the generator is constructed.

The strength of voltage induced in the conductor depends on its speed and on the strength of the magnetic field. The magnetic field may be furnished by a permanent magnet or by current flowing through field coils to form an electromagnet.

The principal components of a DC generator are the armature, commutator, field poles, brushes and brush rigging, yoke or frame, an bells or and frames. In an alternator, the armature coils are held in place in slots in the alternator frame. The field coils are wound on poles or slots around the rotating shaft. The assembly that contains the stationary conductors is called stator. The assembly that includes the rotating poles and field coils is called rotor.