As the flux of a shunt motor remains constant, what is its torque proportional to?

In a shunt motor, the rotor flux remains relatively constant due to its design, where the field winding is connected in parallel with the armature winding. As such, when considering what the torque is proportional to, it is essential to understand the relationship between the torque produced by the motor and the armature current.

The torque generated by a shunt motor can be described by the equation:

[ T \propto \phi \cdot I_a ]

where T is the torque, φ is the flux, and ( I_a ) is the armature current. Because the flux remains constant in this type of motor, the torque is directly proportional to the armature current. As you increase the armature current, while maintaining nearly constant field flux, the torque also increases proportionally.

In summary, for a shunt motor, the torque produced is proportional to the armature current since the flux remains constant. This relationship helps in understanding how the motor responds to changes in load conditions.