Inside an AC Electric Locomotive
This involves a bank of many components like transformers, rectifiers, inverters, capacitors, thyristors, compressors and other such paraphernalia, housed within the locomotive body or the “shell”, and there is no central “Engine” or prime mover.
All this has to be done for optimum performance of the traction motors under different conditions and loads. Bi-Current locomotives work according to the same principles, only they have more equipment packed inside them to enable them to work under both type of currents.
Each one the Pantographs are used to collect a specific type of current only.