DC Motors Download: http://skillcruise.com/academics/electrical-engineering/

1. DC MotorsDC MotorsDC MotorsDC Motors

2. TOPICS TO DISCUSS
• Introduction to DC MOTORS.
• Principle.
• Construction.
• Working.
• Types.
• Applications.

3. • A DC motor or Direct
Current Motor converts
electrical energy into
mechanical energy.
• A direct current (DC)
motor is a fairly simple
electric motor that uses
electricity and a
magnetic field to
produce torque, which
turns the rotor and hence
give mechanical work.
DC MOTORDC MOTOR

4. PRINCIPLE OF DC MOTORSPRINCIPLE OF DC MOTORS
• In any electric motor, operation is based
on simple electromagnetism.
• When a current-carrying conductor is
placed in an external magnetic field, it
will experience a force i.e. Lorentz force.
• Due to this force torque is produced
which rotates the rotor of motor and
hence a motor runs.

5. • DC motor consist of 2 windings…
1. Field winding.
2. Armature winding.
• Field winding is stationary and armature
winding can rotate freely.
• Field windings when given DC supply,
magnetic field is produced.
• Armature winding when connected to
DC source, shaft connected to it rotates
due to Lorentz force.
CONSTRUCTIONCONSTRUCTION

7. WORKING OF DC MOTORSWORKING OF DC MOTORS

8. TYPES OF DC MOTORS
• DC motor are of 3 types they are…..
• DC SHUNT MOTOR
• DC SERIES MOTOR
• DC COMPOUND
MOTOR

9. 1.1. DC SHUNT MOTORDC SHUNT MOTOR
Armature
• The parallel combination of two
windings is connected across a
common dc power supply.
• The resistance of shunt field
winding (Rsh) is always higher than
that is armature winding.
• This is because the number of turns
for the field winding is more than
that of armature winding.
• The cross-sectional area of the wire
used for field winding is smaller
than that of the wire used for
armature winding.

10. 2.2. DC SERIES MOTORDC SERIES MOTOR
• The field winding is connected in series
with the armature.
• The current passing through the series
winding is same as the armature
current .
• Therefore the series field winding has
fewer turns of thick wire than the shunt
field winding.
• Also therefore the field winding will
posses a low resistance then the
armature winding.

11. 3.3. DC COMPOUND MOTORDC COMPOUND MOTOR

12. I.I. LONG SHUNT COMPOUND MOTORLONG SHUNT COMPOUND MOTOR
• In this the series winding is
connected in series with the
armature winding and the
shunt winding is connected in
parallel with the armature
connection.

13. II.II. SHORT SHUNT COMPUND MOTORSHORT SHUNT COMPUND MOTOR
• In short shunt compound
motor the series winding is
connected in series to the
parallel combination of
armature and the shunt
winding
• This is done to get good
starting torque and
constant speed
characteristics.

14. a)a) CUMULATIVE COMPOUND DC MOTORSCUMULATIVE COMPOUND DC MOTORS
b)b) DIFFERENTIAL COMPOUND DC MOTORSDIFFERENTIAL COMPOUND DC MOTORS
• If the two field windings i.e. series and
shunt are wounded in such a way
that the fluxes produced by them
add or assist each other
• If the two field winding i.e. series and
shunt are wounded in such a way
that the fluxes produced by them
always try to oppose and try to
cancel each other.

15. APPLICATIONS OF DC MOTORSAPPLICATIONS OF DC MOTORS
MOTORS.. APPLICATIONS…
D.C. SHUNT MOTOR
LATHES , FANS, PUMPS DISC AND BAND SAW DRIVE REQUIRING
MODERATE TORQUES.
D.C. SERIES MOTOR ELECTRIC TRACTION, HIGH SPEED TOOLS
D.C. COMPOUND MOTOR
ROLLING MILLS AND OTHER LOADS REQUIRING LARGE
MOMENTARY TORQUES.

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