Dc shunt motor work needs direct current. The shunt means a parallel connection in electrical terminology. The armature and field windings in the dc shunt motor are connected in parallel and this kind of field windings are named shunt windings. In the rest of this article, we will discuss the working theory and structure of the dc shunt motor.
The working theory and structure of the dc shunt motor don’t differ from any other dc motors. This type of motor also consist of all the essential components-rotor (armature), stator (field windings) and commutator, which is important to the working of the dc shunt motor. Owing to the interaction between the magnetic field produced around the current carrying armature and the magnetic field emerged around the stator windings, the dc shunt motor will produce a rotational torque. Through the commutator & brushes arrangement, the Current is provided from the stationary housing to the rotating armature. Power is directly acted on the stator, which keeps still.
Stator field windings, made of fine coil of wire with large number of turns, which is used to produce strong magnetic field for heavy currents can’t be handled by small gauge lines, connect with the armature in parallel in the shunt dc motor.
A dc shunt motor can’t be applied in applications, which have a need for high starting torques, because this kind of motor can’t bear high currents. And its shaft load should be small to start working.
Due to the high resistance of the shunt windings, when supply electric voltage to the dc shunt motor, the current flows through the shunt coil is very low. When the armature draws enough current, a strong magnetic field will emerge. Owing to the interaction of magnetic field around armature and the field produced around the shunt field, the motor will begin to rotate. The armature will produce a back EMF when it begin to turn. With the turning of the dc shunt motor, the back EMF will control the armature current and keep it low.