Electrical Interview: INTERPOLES

         These are the small poles fixed to the yoke and spaced in between the main poles. They are wound with comparatively few heavy gauge copper wire turns and are connected in series with the armature so that they carry full armature current.Their polarity, in case of generator,is same that of main pole ahead in the direction of rotation.But in case of motor the pole polarity is opposite to direction. Inter poles reduce the commutation and also reduce the cross magnetization in their location due to that reason universally interpoles are used in dc machines.

TRACTION MOTOR

                                                                 

                                                                             

Most of all the traction system in world use electrical series motors because series motors has high starting torque and easily to control the speed of the motor. But in hill type railway system induction motors are used because in hill type traction we want regenerative braking.In this type traction dc motors do not support the regenerative braking system due to this problem we use the induction motors.Electrical Induction motors are supports the regenerative braking system i.e slip is negative in this condition.