AC/DC railway electrification and protection

The technical strength of all electrification schemes lies in the fact that the prime mover is removed from the train; but this is also its economic weakness. By taking power from a distribution network there is almost unlimited power available which has been efficiently produced but the cost of providing the fixed installations can only be justified where the traffic is heavy or frequency is high. The 25 kV rail network has been designed to meet the needs of a fast, intercity, multi-track railway network carrying a variety of trains at frequent intervals. This operation requires an overhead system that is inherently safe for employees and passengers, reliable and provides a high degree of security of the supply to the traction units. This will ensure that the electrification supply system is able to provide the required power levels to fulfil the performance of the traction units