The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by
A)reducing the field current
B)decreasing the armature current
C)increasing the armature current
D)increasing the excitation current

Question

Quizplus · Accepted Answer

Reducing the field current in a DC shunt motor decreases the flux, which inversely affects the speed according to the formula $N \propto \frac{V - I_aR_a}{\Phi}$, where $N$ is the speed, $V$ is the applied voltage, $I_a$ is the armature current, $R_a$ is the armature resistance, and $\Phi$ is the magnetic flux. Therefore, with reduced flux, the speed increases.

The Speed of a D