TYPES OF DC MACHINES

The principle types of DC machines are;

1. Separately excited DC machine

2. Shunt wound DC machine

3. Series wound DC machine.

4. Compound wound DC machine.

The last three machines comes under self-excited DC machines. In this, current flowing through the field Winding is supplied by machine itself.

1. SEPARATELY EXCITED DC MACHINE

As the name suggests, the field coils are energized by separate DC source.
Figure given below shows the connection diagram for separately excited DC  generator and separately excited DC motor.
Direction of current are  different in generator and motor otherwise they have same construction.

              Separately excited DC Generator.

            Separately excited DC Generator.

                                                      

2. SHUNT WOUND DC MACHINE

A machine in which field coils are connected in parallel with the armature is called a shunt machine.
Shunt field winding receives the full output voltage in case of generator and supply voltage in case of motor, so it is generally provided with fine wire having large number of turns and carries a small field current.
Figure given below shows the connection diagram for DC shunt generator and DC shunt motor.
Direction of current are  different in generator and motor otherwise they have same construction.

                                               

                                                  

                                                        SHUNT WOUND DC MOTOR.

3. SERIES WOUND DC MACHINE

A DC machine in which field windings are connected in series with the armature is called series wound DC machine.
In this case field winding carries the armature current and armature current is high so field Winding are made of thick wire with small number of turns.

Figure given below shows the connection diagram for DC series generator and DC series motor.
Direction of current are  different in generator and motor otherwise they have same construction.

DC SERIES GENERATOR

DC SERIES MOTOR

4. COMPOUND WOUND DC MACHINE

A DC machine having both shunt and series field windings are called compound DC machines
Shunt winding has larger number of turns of thin wire and series Winding has few turns of thick wire.
Compound machine may be connected in two ways.
If shunt field is connected in parallel with the armature only, then it is called short shunt compound DC machine

Figure given below shows the connection diagram for DC short-shunt compound generator and DC short-shunt compound motor.
Direction of current are  different in generator and motor otherwise they have same construction.

SHORT-SHUNT COMPOUND GENERATOR

SHORT-SHUNT COMPOUND MOTOR

When the shunt field winding is connected in parallel with armature and series field, then it is called long-shunt dc compound machine.

Figure given below shows the connection diagram for DC long-shunt compound generator and DC long-shunt compound motor.
Direction of current are  different in generator and motor otherwise they have same construction.

LONG-SHUNT COMPOUND GENERATOR

LONG-SHUNT COMPOUND MOTOR

Besides this, if magnetic flux produced by series field Winding assist or aids the flux  produced by shunt field winding , the machine is called cumulatively compounded DC machine.
If the flux due to series field winding opposes the flux due to shunt field winding, then machine is said to be differentially compounded DC machine.

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