DC Motor

• DC motor or direct current motor is an electrical machine that transforms electrical energy into

  mechanical energy by creating a magnetic field that is powered by direct current.
• When a DC

  motor is powered, a magnetic field is created in its stator.
• The magnetic field attracts and repels magnets on

  the rotor ; this causes the rotor to rotate.
• To keep the rotor continually rotating, the commutator that

  is attached to brushes connected to the power source supply current to the motors wire windings.
• A DC motor is based on the idea that when a current carrying conductor is placed in a magnetic field, it produces

  mechanical force.
• Since DC motors and DC generators have

  the same construction, they can be used interchangeably.
• Basic parts of DC Motor

  1. Stator
  2. Shaft
  3. Terminals
  4. Magnets
  5. Rotor
  6. Coil Windings
  7. Brushes
  8. Commutator
• The stator is the unmoving main body of the motor, and it

  provides support and protection for the motor.
• The stator

  provides a rotating magnetic field that drives the armature

  or rotor.
• It is the static part of the motor that houses the

  field windings and receives the electrical supply through

  its terminals. ( Stator )
• The windings and the commutator rotate the shaft.
• the shaft, which is at the center of the motor and made of a hardened metal, usually steel, to withstand the loads of the application.
• The commutator bars are attached to the plate that

  is affixed to the shaft by plastic molding.
• The torque that is produced by the

  winding is transferred to the shaft supported by the stator.
• The shaft protrudes through the stator and connects the motor to the application.
• A DC motor has two terminals: positive and negative.
• When the positive wire is connected to the positive terminal and the negative wire connected to the negative terminal, the motor rotates clockwise. When they are reversed, the motor rotates counter clockwise.
• The terminals provide the power supply for the motor and are connected to the brushes and brush arms inside the back cover.
• The magnets used in DC motors are referred to as permanent magnets; this means their magnetic field is always active.
• Opposite ends of magnets attract while similar ends repel.
• magnetic field of a magnet runs from the south pole to the north pole.
• The most powerful part of a magnet‘s magnetic field is

  at its ends.
• Two magnets create a very strong field; this is why two magnets are included in a DC motor around the rotor such that the strong magnetic field passes through the rotor.
• The rotor or armature is made of multiple disks that are insulated from each other by laminated sheets.
• The multiple disks prevent the creation of a large eddy current.
• Eddy currents are the reason the plates are insulated.
• For greater motor efficiency, the disks of the rotor are made as small as possible.
• The rotor is the dynamic part of the motor that is used to create the mechanical revolutions.
• The coil windings are wrapped around the rotor.
• The coiling of the wire creates a strong and powerful magnetic field.
• As more coils are added to the rotor, its rotation becomes smoother.
• All DC motors have a minimum of three coils to ensure smooth

  rotation since two coils tend to jam and stop the motor.
• Each coil is 120o from the previous coil.
• The brushes of a DC motor provide the coils with power and are metal pieces that act like springs.
• Brushes. On one side, they have a conductive material

  made of carbon. On the other side, they have a pin where the power

  supply is applied to the motor.
• The commutator is made of small copper plates that are mounted on the shaft and rotate as the shaft rotates.
• Each coil is connected to two commutator plates, which are electrically isolated from each other but connected by the coils.
• With positive and negative terminals connected to two commutator plates, current easily flows

  and an electromagnetic field is generated.