How D. C. Motors Works ?
How D. C. Motors Works ?
A MOTOR WHICH WORKS ON
DIRECT CURRENT SUPPLY… IS TERMED AS D.C. MOTOR
► PRINCIPLE OF D.C. MOTOR
™ The working of a dc motor is based
on the principle that when a current-carrying conductor is placed in a magnetic
field, the conductor experiences a mechanical force, whose direction is given
by Fleming's left hand rule and magnitude is given by
F=BILsin𝜭
►Various Parts of D.C. Motor
Yoke
Pole
Bearing
Armature
Commutator and Brushes
Yoke
It is the outer cover of
motor and it is also
called as frame.
It gives protection to
the rotating
mechanism and other
parts of motor
Bearing
Its purpose in motor is
to support & locate the
rotor, to keep the air
gap small.
It should be
able to operate at low
& high speeds
rotations with
minimum frictional
loses.
Poles
The poles of the machine
are electromagnets. A
winding is placed over the
poles to excite them.
The pole shoes :reduce the
reluctance of the magnetic
path & they support the
exciting coils (or field coils).
Armature
It consists of armature cor
and armature winding.
Core provides low reluctant
path.
Winding cuts the magnetic
flux line and voltage gets
induced in it.
Commutator and Brushes
Commutator converts ac voltage into dc voltage
generated internally.
it helps to produce
unidirectional torque.
Brushes are used to sent the current to the armature
winding through commutators.
Working of D.C. Motor
When the terminals of the motor are connected to an
external source of DC supply:
The field magnets are excited developing alternate
North and South poles
The armature conductors carry currents.
All conductors under North-pole carry currents in
one direction while all the conductors under South pole carry currents in the opposite direction.
The armature conductors under N-pole carry currents into the plane of the
paper (denoted as ⊗ in the figure). And the conductors under S-pole carry
currents out of the plane of the paper.
Since each armature conductor is carrying current and is placed in the
magnetic field, a mechanical force acts on it.
On applying Fleming’s left-hand rule, it is clear that force on each
conductor is tending to rotate the armature in the anticlockwise direction.
All these forces add together to produce a driving torque which sets the
armature rotates.
Application of D.C. MOTOR
THE MOST USEFUL APPLICATION OF D.C.
MOTORS ARE AS FOLLOW: 1. HOISTS AND LIFTS
2. CRANE
3. ROLLING MILLS
4. CONVEYORS
5. TRACTION AND SO ON……
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