A dc series motor is operating at rated speed with rated excitation. It has two resistances R1 and R2 connected across the field and the armature respectively. Speeds above the rated speed can be obtained by
A. increasing R1 only.
B. reducing R2 only.
C. reducing R1 and increasing R2.
D. increasing R1 and reducing R2.
Answer:C
A dc series motor is operating at rated speed with rated excitation. It has two resistances R1 and R2 connected across the field and the armature respectively. Speeds above the rated speed can be obtained by
A. increasing R1 only. B. reducing R2 only. C. reducing R1 and increasing R2. D. increasing R1 and reducing R2.