A 150V, DC motor drives a constant torque load at speed of 1200 rpm, the armature and field resistances are 2Ω and 150Ω, respectively. The motor draws armature current of 9A and field current of 1A.

(a) If the armature voltage increases 10%, calculate the percentage change in no-load speed

(b) Assume that a resistance is added in the field circuit to reduce the field current by 20%, calculate armature current, motor speed, and value of added resistance.

Answer rating: 100% (QA)

Given data V 150 V N 1 1200 rpm I a1 9A R f 150 R a 2 I f 1A E b1 V I a R a 15... View the full answer