Types of DC motor

Types of DC motor
There are three types of DC motor.They are:
(1) Series motor
(2) Shunt motor
(3) Compound motor


(1) Series motor
In series motor the winding is joined in series with the armature conductors.As they carry full load current, field winding consists of a few turns of thick wire.
In series motor supply current I is equal to field current (If) and armature current (Ia) if (Ra) be armature winding resistance and (Rf) be field winding resistance.
I=Ia=If-(1)
V=Eb+(+,-)If Rf+Ia Ra-(2)
=Eb+I (Rf+Ra)-(3)
I=(V-Eb/Rf+Ra)-(4)



(2) Shunt motor:
In shunt motor field winding are connected across or in parallel with the armature conductor.Shunt field winding have maximum resistance.It is wounded many turns with thin wire.The same applied voltage is available in both armature and field winding.
In this type of motor
I= Ia+If-(1)
If= V/Rf-(2)
V= (Eb+Ia Ra)-(3)
Ia= (V-Eb/Ra)-(4)



(3) Compound motor:
In compound motor both shunt and series field is stronger than series field.When the series field flux aids the shunt field flux then motor is said to be commutativity compound motor in which fluxes and series are added.
On the other hand if series field opposes the motor is said to be differentially compound in which the fluxes series are subtracted.