What is a DC Shunt Motor : Construction, Working Principle, Circuit Diagram

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What is a DC Shunt Motor

The shunt wound DC motor falls under the category of self excited DC motors, where the field windings are shunted to, or are connected in parallel to the armature winding of the motor, as its name is suggestive of. And for this reason both the armature winding and the field winding are exposed to the same supply voltage, though there are separate branches for the flow of armature current and the field current as shown in the figure of DC shunt motor below

shunt wound DC motor
shunt wound DC motor

Construction of a Shunt Wound DC Motor

Construction of a Shunt Wound DC Motor
Construction of a Shunt Wound DC Motor

Just that there is one distinguishable feature in its designing which can be explained by taking into consideration, the torque generated by the motor. To produce a high torque,

  1. The armature winding must be exposed to an amount of current that’s much higher than the field windings current, as the torque is proportional to the armature current.

  2. The field winding must be wound with many turns to increase the flux linkage, as flux linkage between the field and armature winding is also proportional to the torque. Keeping these two above mentioned criterion in mind a dc shunt motor has been designed in a way, that the field winding possess much higher number of turns to increase net flux linkage and are lesser in diameter of conductor to increase resistance (reduce current flow) compared to the armature winding of the DC motor. And this is how a shunt wound DC motor is visibly distinguishable in static condition from the DC series motor (having thicker field coils) of the self excited type motor’s category.

Application of a DC shunt motor

application of a DC shunt motor
application of a DC shunt motor

As you can see in above image, even though output torque of DC shunt motor increases comparatively speed doesn’t fall much.

DC shunt motor is also called as constant speed motor.

In other words, if we assume that the supply voltage is constant then flux also becomes constant. At the rated speed the back emf also becomes nearly constant if the load is same.

The various applications of DC shunt motor are in

  1. Lathe Machines,

  2. Centrifugal Pumps,

  3. Fans

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