Eliminating the Catenary Architecture

Electrified sections of Railways (in New Delhi) are very commonly seen, the delhi metro routes particularly, besides the ones of Northern Railways.

Conversion from diesel to electric traction is what most Railways aim to do. Electrification is very popular and has many advantages-the most evident being the reduction in carbon emissions relative to the diesel trains. Some other advantages are higher power to weigh ratio, faster acceleration, higher tractive efforts. There is less to say on the disadvantages, though installation cost is an issue.

Catenary refers to the system of contact and messenger wire ( which supports the catenary wire) which supply electricity to the locomotive.Catenary has become a familiar street furniture in many cities. There are now many catenary free systems being developed and successfully implemented elsewhere in the world.

It is interesting to note that a catenary free rail was introduced in the French city of Tours in the 19th century ! The rail used studs which were activated only when an electromagnet placed under the train passes over it. However it was rendered unfeasible because of some mercury leakage problem.

The third rail and fourth rail system( which use 750V DC) are very popular alternatives to the overhead catenary. In 2003, Bordeaux installed the Alstom APS system which uses 750V conductor rail embedded in the road and is activated when a coded signal from the train as it passes above it. It is successfully running in many parts of Europe and will e used in Dubai also.

Another system- the Ansaldo STS uses box embedded in the road surface a contact plates placed over the box at a distance of approximately 50 c, feeding power from a cable inside the box to the show in the vehicle bogie. These boxes contain path for return current, thus cancelling any inductive effects.

Bombardier's Primove LRV draws supply through induction from a cable buried between running rails which forms the primary circuit. The magnetic field is converted back to electric energy by a pick up coil mounted underneath the train.
The advantage here is that the cable can be laid under any surface and is energized only when the locomotive passes over it-minimizing wear as there is no direct contact.

There have also been many developments in use of NiMH batteries for supply- removing any kind of fixed infrastructure.