The phase exchanger of a Kando-type AC locomotive MAV V40. This unit transformed the one phase 25 kV 50 Hz AC into 3 phase AC. The speed of the locomotive was adjusted by the varying of the poles of the driving motor. This system worked in reverse form providing backfeeding of current upon braking. The picture was taken in the Northern Railway Workshop of Budapest, Hungary.

Photo and scan by Peter Werner Groh (groh@cric.chemres.hu)