While starting a dc shunt motor Reduced armature voltage Va

While starting a dc shunt motor Reduced armature voltage Va and reduced field voltage Vf should be applied and full regulator resistance Rr should be included in the filed circuit reduced Va but full Vf should be applied and Rr should be zero Rated Va and rated Vf should be applied and Rr should be zero Rated Va and rated Vf should be applied and Rr should be maximum

Solution

B) REDUCED Va BUT FULL Vf SHOULD BE APPLIED AND Rf SHOULD BE ZERO.

> AT THE TIME OF STARTING BACK EMF (Eb) IS ZERO.

SO MAXIMUM CURRENT FLOWS.

WE KNOW V=Eb+Ia*Ra

ia=(v-eb)/ra

v=k*if*n+ia*ra

n=(v-ia*ra)/(k*if)

to limit the speed applied voltage is reduced and reduce the field resistance. so maximum filed current flows. so we limit the speed.