Construction of DC machine

DC machine:

DC machine includes the function of generator and motor. Same machine you can use as a generator or motor. There is no change in construction.

If you supply electrical energy to DC machine, it will give you mechanical energy or rotational energy. This is known as motor function. The principle of motor is " whenever a current caring conductor is placed in a magnetic field, it will experience a force and two equal and opposite direction force will create a torque."

If you have mechanical energy in terms of rotation (by prime mover), you can generate electrical energy with the help of DC machine and this function is known as generator. Generator works as principle of electromagnetic induction.

Different parts of DC machine:

1) Yoke:

• It is used to protect internal parts of DC machine.
• Provide support to the pole.
• Complete magnetic path.

          Yoke is made up Cast iron

2) Pole:

• Pole is used to produce magnetic flux inside the DC machine. Pole is made up of low reluctance material like cast iron or cast steel. 

3) Pole shoe:

• Pole shoe is used to spread the magnetic field produced by the poles. Pole and pole shoe are laminated in large machine.

4) Armature:

• Armature provide housing to the armature winding
• It completes magnetic flux path

          Armature is made up of Cast iron. Armature is laminated to reduce the eddy current losses.

5) Armature winding:

• whatever current is produced in case of generator, that current is produce in armature winding and in case of motor, voltage is supplied to the armature winding. It made up of copper.

6) Field winding:

• Field winding is placed on the pole to produce magnetic field inside the DC machine. It is made up from copper.

7) Commutator:

• In case of generator, commutator is used to convert AC current into DC current. In other words, it functions as a rectifier.
• In case of motor, commutator is used to produce unidirectional torque. 

8) Brush:

• Brushes are used to carry current from and to commutator. It is made of carbon.

9) Shaft:

• Shaft is used to transfer mechanical power from prime mover or to load.