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DIRECT CURRENT MOTOR

DIRECT CURRENT MOTOR
Basic Construction
Types
Yoke
outer part called starter - made out of cast iron or cast steel
Field Pole
Field Winding
Armature
Commutator
Brushes
Speed Control
Torque
supports the field poles and field winding
provides a magnetic path to the main field flux
acts as a protecting cover for the whole machine
mounted inside the yoke - made of thin lamination stacked together and consist of pole cores and pole shoes
provides support to the field winding
provide slow reactance path to the main field flux
distributes the main field flux uniformly all around the periphery of the armature
the field coils are wound on the poles
Armature Core
elements which are connecting the armature windings (through commutator)
to the external terminal of the motor
consists of copper segments tightly fastened together with mica/micanite
insulating separators on an insulated base
they produce a magnetic field when D.C. is passed through them.
Armature Windings
It houses the windings in the slot - made of sheet-steel
laminations
is the heart of the DC motor in which the torque is
developed.
provides a low reactance path to the main field flux and the armature flux
it produces armature flux when current is passed through them. This flux reacts with main field flux and produces rotation or torque.
it collects D.C. from brushes, converts it into A.C. and supplies to the armature windings.
it collects D.C. from brushes, converts it into A.C. and supplies to the armature windings.
Self-Excited
Separately Excited
Permanent Magnet
Shunt
Series
Compound Excited
the field winding is connected in parallel with the armature
the field winding is connected in series with the armature winding
the field coils or field windings are energised by a separate DC source
A DC Motor having both shunt and series field windings
uses a permanent magnet to create the magnetic field required for the operation of a DC motor
Armature resistance control (Rheostat Control)
Variation of field flux Ф (Field flux control)
Armature Voltage control