Functions of equipment: 1) circuit breaker: disconnects the locomotive equipment from the supply in the event of fault in the equipment / loco. 2) On load tap changer, used to control the voltage to the traction motors through the rectifier for speed control. 3) Traction transformer, steps down the voltage to the suitable value for the traction motor. It has a ratio of 20:1. 4) Rectifier: converts input AC to DC for further use by series traction motors. 5) Smoothing reactor/choke: smoothen out the ripples in the DC output current of rectifier. 6) Traction motor: operates as per the required operating characteristics to take on the traction load.