Exam Question

(a) Discuss different methods of speed control of a d.c. series motor by adjusting field ampere turns. (6)

(b) A 230 V, d.c. shunt motor runs at 1000 r.p.m and takes 5 amperes. The armature resistance of the motor is 0.025Ω and shunt field resistance is 230Ω Calculate the drop in speed when the motor is loaded and takes the line current of 41 amperes. Neglect armature reaction. (10)