Describe the parts of a DC machine (rotor, stator, interpoles, field winding, armature winding), list two types of brushes, and state the function of the commutator.

Here are the answers to the questions from Assessment activity 4.2.

1. Briefly describe the following parts of a DC machine:

• a) Rotor: The rotating part of the DC machine. It contains the armature winding, which interacts with the magnetic field to produce torque or induce voltage.
• b) Stator: The stationary part of the DC machine. It houses the field windings or permanent magnets that create the main magnetic field.
• c) Interpoles: Small auxiliary poles located between the main poles. They are used to reduce armature reaction and improve commutation by neutralizing the reactive voltage in the commutating coils.
• d) Field winding: Coils wound around the main poles of the stator. When energized, they produce the main magnetic field necessary for the machine's operation.
• e) Armature winding: The main current-carrying coils wound on the rotor. This is where the electromotive force (EMF) is induced in a generator or where the torque is produced in a motor.

2. List two types of brush that are used in DC machines.

1. Carbon brushes
2. Graphite brushes

3. What is the main function of the commutator?

The main function of the commutator in a DC machine is to convert the alternating current (AC) induced in the armature windings into direct current (DC) at the terminals (in a generator) or to reverse the direction of current in the armature windings to maintain continuous, unidirectional torque (in a motor).

4. What is the purpose of a rotor in a DC machine?

The purpose of the rotor in a DC machine is to serve as the rotating component that carries the armature winding. This winding interacts with the magnetic field produced by the stator to either generate electrical power (as a generator) or produce mechanical power (as a motor).