Electrical Engineering ⇒ Topic : DC Generator

An electrical generator is a machine that converts mechanical energy to electrical energy. Here energy conversion is based on the principle of the production of dynamically induced e.m.f. In DC generator, the magnetic flux is static and the armature is rotated by the prime mover. The armature conductors cut the magnetic flux. Therefore, the current that flows through the conductors are also alternating in nature. The e.m.f. induced in the armature conductor is alternating in nature. The DC generators are generally classified into two main categories depending upon the field excitation:

1. Separately-excited generator

2. Self-excited generator

Direct current (dc) generators are used to generate electricity which is unidirectional in nature. They can be designed to supply power ranging from a few kilo-watts to hundreds of kilowatts. A dc generator is a rotating machine which converts mechanical energy into electrical energy. Its working is based on the principle of dynamically induced emf, in a moving conductor in a stationary magnetic field .If a conductor of active length 1 metres moves in a steady magnetic field of strength B Wb/m2 with a uniform velocity of u metres/second, then the dynamically induced emf in the conductor is given by

where 0 is the angle between the velocity vector u and the field vector B. The above expression suggests that for the generation of dynamic emf, three requirements must be met. They are (1) a magnetic field should be present,(2) a conductor must be present, and (3) the conductor should more relative to the magnetic field. A dc generator depicts the above equation. The field system of the generator provides the magnetic flux, the armature carries therequired number of conductors, and the motion of the conductor is provided by the motor which drives the armature of the generator. The mechanical device used to rotate the armature is sometimes known as the prime mover. In most of the dc generators, the armature is rotated and the field system is kept stationary. 

D.C GENERATOR An electrical generator is a machine which converts mechanical energy (or power) into electrical energy (or power).