2. AC GENERATOR
• It is also called dynamo or alternator.
• It converts one form of energy into another form
,i.e, Mechanical to Electrical energy.
• It operates through the interaction between a
magnetic field & coil.
• It is work on the principle of ELECTROMAGNETIC
INDUCTION
3. Principle
• The working of an A.C. generator is based on
the principle of "electromagnetic inducion".
• When a coil is rotated in a uniform magnetic field
with its axis perpendicular to the magnetic field.
• The magnetic flux linked with the coil changes
and an induced emf and hence a current is set
up in it.
5. Field magnet
• It is a powerful electromagnet or permanent
magnet.
• It produce strong
magnetic field in the
region between its pole.
6. Armature
• It consists of a rectangular coil having a large
number of turns of insulated copper wire wound on
a soft iron cylinderical core.
• It can be rotated in the magnetic field of the field
magnet about an axis perpendicular to field.
7. Slip rings
• Two ends of armature coil are connected to two
coaxial brass ring called slip rings.
• A slip rings are rigidly fixed to same shaft which
is used to rotate the coil.
• As the armature coil rotate
the slip rings also rotates
about the same axis of
rotation
8. Brushes
• Two graphite or flexible metalic rods called
brushes are lightly pressed against slip rings.
• Through brushes the
current induced in the
armature coil is fed to
the external circuit by
the means of line wires.
9. Prime mover
• The prime mover is the component that is
used to drive the AC generator.
• The prime mover may be any type of
rotating machine,such as diesel engine, a
steam turbine, or a motor.
10.
11. Working
• The ac generator uses
Faraday's laws of
induction, it consists of a
coil of wire rotating a
magnetic field. As the coil
rotates it cuts the magnetic
flux generating an EMF,
the EMF produced is given
by Faraday's law. The
angle is changing at the
angular frequency ω.
12. Working
• The ac generator uses Faraday's laws of
induction, it consists of a coil of wire rotating a
magnetic field. As the coil rotates it cuts the
magnetic flux generating an EMF, the EMF
produced is given by Faraday's law. The angle is
changing at the angular frequency ω. Therefore
at a given moment in time the angle between the
normal to the area and the magnetic field lines
will be ωt. Therefore the flux linkage, φN will be
BAN cos(ωt). Differentiating cos(ωt) function
with respect to time gives -ω sin(ωt).
13. Working
• Therefore, the EMF is given by
• The electrons flow first in one direction and
then, in the other. The generator produces an
alternating current.
15. Application
• Electric generators:
Alternators are used in modern
automobiles to charge the battery and
to power the electrical system when its engine is
running.
• Diesel electric locomotive alternators:
Diesel electric locomotives and
diesel electric multiple units, the
prime mover turns an alternator
which provides electricity for thetraction motors
16. Application
• Marine alternators:
Marine alternators used in yachts are similar to
automotive alternators, with appropriate
adaptations to the salt-water environment.
