With the help of neat diagrams,explain the following methods of speed control in DC series motor. i) Field diverter method. ii) Armature diverter method.
(i) Field diverter method: - Resistance connected in parallel with field winding -By adjusting this resistance current can by diverted from field winding -Thus field current decreases and the speed can be increased above rated speed.
(ii) Armature diverter method: - Resistance is connected in parallel with armature winding. -This diverter resistance shunts some of the line current, thus reducing armature current. -Now for a given load if the armature current decreased, the flux must increase and hence speed is decreased than the rated speed.