The characteristics of a d.c. series machine self-excited by rectified current for purposes of regenerative control

The present position of regenerative control for tramcars is discussed, and a description is given of a method of self-exciting the field of a series motor with a low-voltage rectified current transformed from alternating-current tappings in the armature. Under these conditions the motor behaves like a shunt machine, and. characteristics are shown when it is acting regeneratively and also when it is used as a generator and motor. Calculations are given for finding the conditions of sparkless commutation of the rectifier, and tests are included which corroborate the calculations. In conclusion, some points are discussed with regard to the practical application of the device.