DC
Machine:
DC
machines are of two types;
1.
DC Motor
2.
DC generator
·
A DC machine is a device that converts
Mechanical energy into electrical energy into electrical energy.
·
When device acts as a generator, the mechanical
energy is converted into electrical energy.
·
On the other hand, when device acts as as a
motor, the electrical energy is converted into mechanical energy.
Parts
of field system.
|
Parts
of armature system.
|
Magnetic frame/yoke
|
Armature core
|
Pole core and pole shoe
|
Armature winding
|
Main field winding
|
Commutator
|
Interpoles/ commutating poles
|
Brushes & Bearings, Interpol
winding
|
STATOR:
Magnetic
frame/ Yoke:
·
The outer frame of the DC Machine is called the
yoke and is normally made of cast iron for small machine, while for large
machines cast steel or rolled steel is employed.
·
Yoke generally serves two purposes.
·
It provides mechanical support to the poles and
acts as a protecting cover for the whole machine.
·
It provides a return path of low reluctance to
the magnetic flux produced by the poles.
Fig:
General view of DC Machine.
FIELD
SYSTEM:
·
The object of the field system is to create a
uniform magnetic field within which the armature rotates.
·
Field system consists of three parts namely pole
cores, pole shoes and magnetizing coils or field coils.
·
The field magnets consists of pole cores and
pole shoes.
·
Pole core is usually of circular section &
is used to carry the coils of insulated wires carrying the exciting current.
·
Field coils or windings, which consists of
copper wire or strip wound around the pole pieces.
·
When current passes through the coil, the coil
magnetize the poles, which produce the necessary flux that is cut by revolving
conductors.
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