DC Series Motor

Type of DC motor- 
There are three types of DC motors and their type depends on the connection of their area wide.
1. Series motor
2. Shunt Motor
3. Compound Motor
(A) Cumulative Compound Motor
        (I) Long Shunt
        (II) Short Shunt
(B) Differential Compound Motor
        (I) Long Shunt

        (II) Short Shunt

1.    Series  motor-

The series field winding of these motors is made of low turns and thicker of coarse laminated wire and it is added to the series of armature from which the full load current flows the same between the armature and the field winding. Due to the series field thicker wire, its resistance is less and due to less resistance, the voltage drop in this winding is less. The current of this motor depends on the load. These motor carry less current at lower loads and more current at higher loads. The speed of the series motor also depends on the load  at low loads this motor rotates at high speed and at no load their speed becomes very high, so this type of motor should never run without load. This motor rotates at low speed at high load. The initial torque of these motors is high.

Line Current In Series Motor = IL=Ise=Ia

Voltage drop in armature = IaRa

Voltage drop in series field winding = Ise Rse = IaRse

Induced Back EMF In armature= Eb =V-Ia(Ra+Rse)

                   Ia=(V-Eb)/(Ra+Rse)

Induced power in motor armature = EbIa watts

Copper loss in armature = Ia²Ra

Copper loss in series field winding= Ise²Rse = Ia²Rse

Input power of motor = V X I_L=V X Ia                       (Because I_L=I_a)

Generated power -

= Input Power – Losses in (armature winding+ field winding)

= VIa-Ia²(Ra+Rse)

Uses: - Where a high initial force is required, a range motor is used predominantly. These motors are mainly used in trams, cranes, trains and electric traction, hoists etc.