Q1. What are different types of DC machines?
Different types of DC machines are-
1. Separately excited D.C. machine:
When a separate D.C. source is used to energize the field coils it is called as
separately excited D.C. machine. The connections showing the separately excited
D.C. Machines are given in the figure.
Figure: (a) Separately excited D.C. Generator, (b) Separately excited D.C.
Motor.
2. Shunt wound D.C. Machine:
Shunt wound D.C. Machines is the machine in which field coils are connected in
parallel with the armature. Since the shunt field receives the full output voltage of a
generator or the supply voltage of a motor, it is generally made of a large number of
turns of fine wire carrying a small field current.
3. Series wound D.C. Machine:
Series wound D.C. Machines is the machine in which the field coils are connected in
series with the armature. The series field winding carries the armature current, and
the armature current is large, that is why series field winding consists of few turns of
wire of large cross-sectional area.
, Figure: (a) D.C. series generator (b) D.C. series motor.
4. Compound wound D.C. machine:
A Compound machine is a machine which has both shunt and series fields. Two
windings are carried out by each pole of the machine. The series winding has few
turns of large cross-sectional area, and the shunt windings have many turns of fine
wire.
It can be connected in two ways. If the shunt field is connected in parallel with the
armature alone, the machine is called the short-shunt compound machine and if
the shunt field in parallel with both the armature and series field, the machine is
called the long-shunt compound machine.
Figure: (a) Short-shunt compound D.C. generator (b) Short-shunt
compound D.C. motor.
Different types of DC machines are-
1. Separately excited D.C. machine:
When a separate D.C. source is used to energize the field coils it is called as
separately excited D.C. machine. The connections showing the separately excited
D.C. Machines are given in the figure.
Figure: (a) Separately excited D.C. Generator, (b) Separately excited D.C.
Motor.
2. Shunt wound D.C. Machine:
Shunt wound D.C. Machines is the machine in which field coils are connected in
parallel with the armature. Since the shunt field receives the full output voltage of a
generator or the supply voltage of a motor, it is generally made of a large number of
turns of fine wire carrying a small field current.
3. Series wound D.C. Machine:
Series wound D.C. Machines is the machine in which the field coils are connected in
series with the armature. The series field winding carries the armature current, and
the armature current is large, that is why series field winding consists of few turns of
wire of large cross-sectional area.
, Figure: (a) D.C. series generator (b) D.C. series motor.
4. Compound wound D.C. machine:
A Compound machine is a machine which has both shunt and series fields. Two
windings are carried out by each pole of the machine. The series winding has few
turns of large cross-sectional area, and the shunt windings have many turns of fine
wire.
It can be connected in two ways. If the shunt field is connected in parallel with the
armature alone, the machine is called the short-shunt compound machine and if
the shunt field in parallel with both the armature and series field, the machine is
called the long-shunt compound machine.
Figure: (a) Short-shunt compound D.C. generator (b) Short-shunt
compound D.C. motor.
