In this article we learn about the working principle of alternator ,and their construction and application . we will also discuss in detail about the different loading motor. working principle of alternator
Ferade law
“The rate of change of flux is directly proportional to
induce EMF in the coil or conductor .”
Which is according for generation of electrical power
following requirement?
1.
Conductor
2.
Magnetic field
3.
Relative speed between them
This type when conductor and magnetic
field are near to each other and in both any one movable them EMF induces in
the conductor. Which direction depends on Fleming right hand rule.
Difference between Alternator and
DC generator
DC generator field winding is
static and armature is movable but in case of Alternator field winding is
movable and armature is static.
Normally Alternator are separately
excited .which required DC supply for field winding so a small self excited DC generator are also
connect with Alternator and made alternator self excited.
From prime mover when Alternator
shaft rotate then DC exciter also rotate and generate supply given to field
winding of alternator. so a constant flux generate in the field winding when
Rotor rotate relative speed develop
between armature winding and magnetic flux so EMF induce in the armature
winding . Armature winding are sinusoidal distributed hence generate EMF are
also sinusoidal. For more know about the working principle of alternator it is required to know about the armature and stator.
Advantages of stationary Armature and Rotating field
1.
DC winding are weight less hence easier them
high speed.
2.
There is not use of brushes so sparking problem
are also reduced.
3.
For insulation purpose also useful
4.
For cooling purpose it is also useful.
Construction of Alternator.
Main parts of Alternator
1. Stator Frame
IT is made from silicon steel and
used to provide support of alternator . In stator frame ventilation are also
keep which use for colling . so the working principle of alternator also depend on construction of alternator.
2. Stator core
Its made from iron or steel alloy
which helpful for flux linkage. Core
used for hold of armature winding .it also use for reduced of eddy
current losses . In stator core three
type slots are used for armature winding .
1. Wide open slots
2 semi open slots
3. Wholly closed slots
3. Rotor
In Alternator two types of rotor are used
1. Salient pole rotor
2. Cylindrical rotor
1. Salient pole rotor
Salient pole rotors axial length are less and diameter are more. In this
rotor number of poles is more and speed of alternator is less. In this rotor
flux distribution is better between field winding and armature winding.
2.Cylindrical Rotor
In
this type rotor length of rotor is more and diameter is less. It is used for
high speed (3600 rpm) in case steam
turbine . in this type rotor number of
poles is two or four. Hence it is the working principle of alternator. For better understand the working principle of alternator pleaz sea this video. If any error above pleaz comment in comment box.