feeder station
A facility that takes power from the national grid and feeds it to overhead electrification lines on a railway.
feeder station: where grid power enters the rails
A feeder station is a substation that converts alternating current from the public electricity grid into the voltage and frequency needed by a railway's overhead contact system. It sits at the boundary between national power infrastructure and railway traction supply, typically receiving 110 kV or higher from transmission lines and stepping down to the 15 kV or 25 kV used by most European or North American rail networks respectively.
The station houses transformers, circuit breakers, disconnectors, and protection equipment housed in a building or outdoor compound. Power flows from the grid through the primary transformer, where voltage is reduced and (if necessary) frequency is converted. Crucially, the output is then fed to the overhead line through autotransformers or step-down transformers at multiple points along a section of track, typically every 5 to 10 kilometres. This distributed feeding prevents excessive voltage drop and unequal loading on any single feeder point.
Redundancy and fault clearance
A well-designed railway electrification scheme has feeder stations spaced so that if one fails, trains can still draw power from adjacent stations. The station includes rapid protection systems: if a short circuit occurs on the overhead line (perhaps from a pantograph contact failure or a fallen conductor), the circuit breaker at the feeder station must detect and isolate the fault within milliseconds to prevent damage to trains and infrastructure. Modern systems use digital relays and earth-leakage detection to achieve this.
Feeder stations are staffed only during commissioning or maintenance; routine operation is fully automated and monitored remotely by the network control centre. A single feeder station may serve 20 to 40 kilometres of double-track main line, depending on traffic density and power demand. Electrified railways with heavy freight or frequent passenger services require more feeder stations than lightly-used lines.
The term reflects the engineering hierarchy: the grid supplies power to the feeder station, which then feeds the traction supply network. Unlike a simple junction substation on a road network, a railway feeder station is always designed to handle the specific impedance, switching speed, and earth leakage profile of overhead line infrastructure.