A DC motor works by converting DC power into mechanical energy using the principle that a current-carrying conductor placed in a magnetic field experiences a mechanical force. It has a field system including field windings that generate a magnetic field, an armature with windings on a core, and a commutator that redirects current flow to keep the torque moving the motor. The speed of a DC motor can be controlled by changing the current through the field windings to adjust the magnetic flux or by changing the armature resistance to vary the voltage applied to the armature. Common DC motor types include shunt, series, and compound motors used in various applications like fans, pumps, machine tools, locomotives, and industrial equipment.

1. Working principle of
DC motor

2. DC MOTOR
DC motor stands for direct current motor. A machine that
converts dc power into mechanical energy is known as dc
motor. Its operation is based on the principle that when a
current carrying conductor is placed in a magnetic field, the
conductor experiences a mechanical force.

3. DIRECTION OF FORCE
The direction of force can be studied by Maxwell’s cork screw
rule.
According to this rule , hold the cork screw in your right hand &
rotate it clockwise direction in such a way that it advances in the
direction of current . Then the direction in which hand rotates is
the direction of force .

4. WORKING PRINCIPLE
1. A generator works on the principle of Faraday’s law of
electromagnetic induction .
2. Whenever a conductor is moved in the magnetic field , an
emf is induced & the magnitude of the induced emf is directly
proportional to the rate of change of flux.
3. Emf causes current flow if the conductor circuit is closed
4. When electric current passes through a coil in magnetic field ,
the magnetic force produces torque which turns the motor.
5. Magnetic force acts perpendicular to both wire and magnetic
field.

5. PARTS OF DC MOTOR
• Field system
• Armature core
• Armature winding
• Commutator
• Brushes
• Field winding
• Rotor & rotor winding

6. ESSENTIAL POINTS
• Critical Field Resistance- For Appreciable Generation Of Emf,
The Field Resistance Must Be Always Less Certain
Resistance, That Resistance Is Called As The Critical
Resistance Of The Machine .
• Back Emf- The Induced Emf In The Rotating Armature
Conductors Always Acts In The Opposite Direction Of The
Supply Voltage .

7. SPEED CONTROL OF DC MOTOR
• Flux control method: By Changing the flux by controlling the
current through the field winding.
• Armature control method: By Changing the armature
resistance which in turn changes the voltage applied across
the armature

8. TYPES OF DC MOTOR
• Shunt motor
• Series motor
• Compound motor

9. APPLICATION OF TYPES OF DC MOTOR
• SHUNT MOTOR:
• BLOWERS AND FANS
• CENTRIFUGAL AND RECIPROCATING PUMPS
• LATHE MACHINES
• MACHINE TOOLS
• MILLING MACHINES
• DRILLING MACHINES

10. • SERIES MOTOR:
• CRANES
• HOISTS , ELEVATORS
• TROLLEYS
• CONVEYORS
• ELECTRIC LOCOMOTIVES
APPLICATION OF TYPES OF DC MOTOR

11. • COMPOUND MOTOR:
• ROLLING MILLS
• PUNCHES
• SHEARS
• HEAVY PLANERS
• ELEVATORS
APPLICATION OF TYPES OF DC MOTOR