Introduction
The greater percentage of the electrical machines in service are a.c. machines, the d.c.
machines are of considerable industrial importance.
The principal advantage of the d.c. machine, particularly the d.c. motor, is that it
provides a fine control of speed. Such an advantage is not claimed by any a.c. motor.
However, d.c. generators are not as common as they used to be, because direct current,
when required, is mainly obtained from an a.c. supply by the use of rectifiers.
Nevertheless, an understanding of d.c. generator is important because it represents a
logical introduction to the behaviour of d.c. motors.
Indeed many d.c. motors in industry actually operate as d.c. generators for a brief
period.
DC Generator
An electrical generator is a machine which converts mechanical energy (or power) into
electrical energy (or power).
The energy conversion is based on the principle of the production of dynamically
(or motionally) induced e.m.f.
whenever a conductor cuts magnetic flux, dynamically induced e.m.f. is produced in it
according to Faraday’s Laws of Electromagnetic Induction. This e.m.f. causes a current to
flow if the conductor circuit is closed.
The direction of induced e.m.f. (and hence current) is given by Fleming’s right hand
rule. Therefore, the essential components of a generator are:
(a) a magnetic field
(b) conductor or a group of conductors
(c) motion of conductor w.r.t. magnetic field
The greater percentage of the electrical machines in service are a.c. machines, the d.c.
machines are of considerable industrial importance.
The principal advantage of the d.c. machine, particularly the d.c. motor, is that it
provides a fine control of speed. Such an advantage is not claimed by any a.c. motor.
However, d.c. generators are not as common as they used to be, because direct current,
when required, is mainly obtained from an a.c. supply by the use of rectifiers.
Nevertheless, an understanding of d.c. generator is important because it represents a
logical introduction to the behaviour of d.c. motors.
Indeed many d.c. motors in industry actually operate as d.c. generators for a brief
period.
DC Generator
An electrical generator is a machine which converts mechanical energy (or power) into
electrical energy (or power).
The energy conversion is based on the principle of the production of dynamically
(or motionally) induced e.m.f.
whenever a conductor cuts magnetic flux, dynamically induced e.m.f. is produced in it
according to Faraday’s Laws of Electromagnetic Induction. This e.m.f. causes a current to
flow if the conductor circuit is closed.
The direction of induced e.m.f. (and hence current) is given by Fleming’s right hand
rule. Therefore, the essential components of a generator are:
(a) a magnetic field
(b) conductor or a group of conductors
(c) motion of conductor w.r.t. magnetic field
