The figure shows plots of speed (N) vs armature current (Ia) of a dc motor for two different operating conditions. Which one of the following features is relevant?
1
(1) represents stronger shunt field, and (2) represents stronger series field of a compound motor
2
(1) represents stronger series field, and (2) represents stronger shunt field of a compound motor
3
(1) represents only shunt excitation, and (2) represents only series excitation
4
(1) represents only series excitation, and (2) represents only shunt excitation