A dc machine is a device which converts mechanical energy into electrical energy into mechanical energy or vice versa. When the device or machine acts as a generator mechanical energy is converted into electrical energy and when machine acts as motor electrical energy is converted into mechanical energy. Dc generator and motors are very similar to each other in essential parts and construction.
1) Field Magnet: It is a strong permanent magnet incase of small machine or an electromagnet incase of large machine which is comprise of following parts:
a. Pole Pieces: They are pole cores made of cast steel with laminated shoes screws on the outer body of machine.
b. Field windings (Pole Coils): It is a coil wound around the pole pieces. When dc current pass through it magnetic field required in machine is generated.
2) Armature Coil: it is a coil wound on a laminated core of soft iron. Armature is placed between the poles of magnets and is free to rotate about its central axis.
3) Commutator and Brushes:
Commutator and brush converts the ac current produced (or required) in armature conductors into (or from) DC current on terminals. Commutator consists of wedge-shaped copper segments, insulated fron each other a nd assembled side by side to form a ring.
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