D.C. Shunt Motor

       In this type, the field winding is connected across the armature winding and the combination is connected across the supply, as shown in the Fig. 1.

Fig. 1 D.C. shunt motor

       Let R_sh be the resistance of shunt field winding.

       R_a be the resistance of armature winding.

       The value of R_a is very small while R_sh is quite large. Hence shunt field winding has more number of turns with less cross-sectional area.

1.1 Voltage and Current Relationship

       The voltage across armature and field winding is same equal to the supply voltage V.

The total current drawn from the supply is denoted as line current I_L.

                       I_L = I_a + I_sh

                      Ish = V/R_sh

      and            V = E_b  + I_a R_a + V_brush 

      V_brush is generally neglected.

      Now flux produced by the field winding is proportional to the current passing through it i.e. Ish.

Note : As long as supply voltage is constant, which is generally so in practice, the flux produced is constant. Hence d.c. shunt motor is called constant flux motor.

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Brushless D.C. Motor 

Swinburn's Test or No Load Test

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