What is a Substation in rail power systems and what does it supply?

• A. A device that switches trains at junctions.
• B. A facility that converts and regulates incoming electrical power into traction power for the railway network, supplying feeders.
• C. A line that carries power from a substation to trackside equipment.
• D. A signaling circuit that detects train presence.

Answer: (B)

A substation in rail power systems is the facility that converts and regulates incoming electrical power into the traction power used by the railway, and it supplies the feeders that distribute that power along the network. It typically houses transformers to match voltage levels, rectifiers or converters to shape the power for traction, and switchgear and protection devices to control and safeguard the supply. The output of a substation goes onto traction feeders that run along the tracks to deliver energy to trains.

This isn’t a junction device that switches trains, nor a simple line that merely carries power to trackside equipment, nor a signaling circuit. Those parts serve different functions, while a substation’s core job is to provide the properly conditioned traction power to the network.