EMC for railway applications (EN 50121)
Railway EMC: the EN 50121 series, how emissions from the railway system and the apparatus are treated, and the specific environment of traction power.
Railways combine extreme power levels (traction supply and motors), sensitive signalling and telecommunications, and a physical layout that runs through every kind of environment. EMC has to cover the railway as a whole system, the vehicles and the apparatus installed in them or along the track.
The standard family
The EN 50121 series, “Railway applications — Electromagnetic compatibility”, has parts for each level; the equivalent international series is IEC 62236:
| Part | Subject (summary) |
|---|---|
| EN 50121-1 | General |
| EN 50121-2 | Emission of the whole railway system to the outside world |
| EN 50121-3-1 | Rolling stock: train and complete vehicle |
| EN 50121-3-2 | Rolling stock: apparatus |
| EN 50121-4 | Emission and immunity of signalling and telecommunications apparatus |
| EN 50121-5 | Emission and immunity of fixed power supply installations and apparatus |
Why railway EMC is different
- Traction power at high voltage (AC and DC systems), with pantographs, converters and switching creating strong, varied disturbances.
- Long conductors: the track, overhead lines and cables act as antennas and as conducted paths.
- Signalling and communications (track circuits, radio systems, balises) must work close to the traction system.
- Emission limits for the whole railway system are expressed at a defined distance from the track, to protect neighbouring radio services.
- Immunity tests include the usual radiated and conducted tests plus tests tailored to the railway environment, such as surges and transients on the supply.
Where to check
The standard parts apply according to the type of equipment and the application; the railway authority, the infrastructure manager and the notified or designated body for the project define the exact requirement.