Traction power network

The installation of a separate traction network generally is done only if the railway in question uses alternating current (AC) with a frequency lower than that of the national grid, such as in Germany, Austria and Switzerland.

There is no reason today to apply different frequencies or current types than for transmission and for industrial usage.

However, the advantage with DC traction was the easier transmission with single copper wires to the feeder points.

The advantage with AC traction is the easier transmission over long distances to the feeder points.

Beyond these parameters and securing former investment, no evidence exists to stay with different current schemes in networks.

The Mariazell railway in Lower Austria operates on single phase AC at a 25 Hz utility frequency.

The traction current supply lines from the nuclear power station Neckarwestheim to the traction current switching station at Neckarwestheim and from there to the central substation in Stuttgart, Zazenhausen are implemented as a four-bundle conductor circuit.

Unlike in Western Germany, there are no dedicated power plants for railway electricity.

A further power station, at Kjofossen feeds single phase AC directly in the overhead wire.

In Denmark and Finland, 50 Hz is used for the main lines (if electrified) and the electricity comes from general suppliers.

Electrification in Natal was stimulated by the takeover of the South African Railways' system by the Electricity Supply Commission (now Eskom) based on the Colenso Power Station.

As is the case for all symmetrical powerlines there are also at traction power lines twisting points.

Because overhead line pylons possess a smaller cross section than traction current masts, these cross beams have to be quite narrow, so the arrangement of four conductor cables in one level, which is standard at traction current lines, cannot be used.