What is a DC Motor?
DC machines can be classified into two types called as DC Motor and DC Generator. An Electrical Motor is a machine which converts electrical energy into mechanical energy. In a DC motor, we supply it with direct current which is then converted into mechanical rotation or energy. DC motor was invented in 1886 by William Sturgeon. There are a lot of applications of DC motor like fans, elevator, cranes, etc. A DC motor can run on DC supply as well as single phase AC supply.
Construction of DC Motor
Different parts of DC Motor are:
- Armature or Rotor: The armature of a DC motor is a rotating part that rotates on its axis. It is a cylinder of magnetic laminations that are insulated from one another. The armature is perpendicular to the axis of the cylinder and is separated from the field coil by an air gap.
- Field Coil or Stator: It is a non-moving part on which winding is wound to produce a magnetic field. This electromagnet has a cylindrical cavity between its poles.
- Yoke: It is an outer frame and it provides mechanical strength to whole assembly of motor. It is made up of cast iron or steel.
- Pole Shoe: It enlarges region of pole, so that the flux can be spread out within the air-gap as well as extra flux can be passed through the air space toward armature. The materials used to build pole shoe is cast iron or steel.
- Pole: It is an electromagnet and the field winding is wounded on pole. Whenever field winding is energized then the pole gives magnetic flux. The materials used for this are cast steel, cast iron. It can be built with the annealed steel laminations for reducing the power drop because of the eddy currents.
- Commutator: It is a cylindrical structure that is made of copper segments stacked together but insulated from each other. The primary function of a commutator is to supply electrical current to the armature winding. It helps in producing steady rotating torque.
- Brushes: The brushes of a DC motor are made with graphite and carbon structure. These brushes conduct electric current from the external circuit and provide it to the rotating commutator.
Working of DC Motor
The Working principle of DC motor is, when kept in a magnetic field, a current-carrying conductor gains torque and develops a tendency to move. So, when electric fields and magnetic fields interact, a mechanical force arises. This is the principle on which the DC motors work.
A magnetic field arises in the air gap when the field coil of the DC motor is energised. The created magnetic field is in the direction of the radii of the armature. The magnetic field enters the armature from the North Pole side of the field coil and “exits” the armature from the field coil’s South Pole side. The conductors located on the other pole are subjected to a force of the same intensity but in the opposite direction. These two opposing forces create a torque that causes the motor armature to rotate.
Applications of DC Motor:
There are various applications for which DC motor is used:
- Lathe Machine
- Machine tools
- Drilling Machine
- Elevators, etc.
In Ceiling Fans, DC motor fans are preferred because they are less nisy and consume less energy than the AC motor fans. They alllso have different speed options to them.