The harmonized standard EN 50121-3-2

The EN 50121-3-2 standard concerns the aspects of electromagnetic compatibility of equipment installed on board rail and tram vehicles.

It specifies the requirements that these products must satisfy in terms of emissions and immunity, taking into account the railway environment and interference generated by other equipment on board.

The EN 50121-3-2 standard is prepared and issued by CENELEC (European Committee for Electrotechnical Standardization) which is the European committee for electrotechnical standardization.

Field of application: the standard applies to the emissions and immunity aspects of electromagnetic compatibility for electrical and electronic equipment intended for use on rolling stock and with frequency ranges up to 400 GHz.

Examples of equipment for installation on rail and tram vehicles are:

  • devices for recording and storing data (dataloggers);
  • emergency intercoms;
  • signaling display;
  • speakers.


The railway infrastructure presents a complex electromagnetic environment made up of many signaling, traction, telecommunications and radio communications systems.

Electromagnetic compatibility (EMC) between electrical and electronic systems is an essential requirement for the safe and reliable operation of equipment. It is all too clear that interference caused by traction systems can disturb signaling equipment, with potentially dangerous consequences.

The main problem of electromagnetic compatibility in the railway environment is the differentiated function of the rails. Originally the rails were solely a mechanical guiding system, but the advent of electricity and technological growth have made the railway infrastructure a complex system in which different pieces of equipment interact. The presence of technologically advanced and "historic" equipment makes the problem of interference an extremely important issue.



The specific harmonized standards for the railway sector are the EN 50121 standards which regulate the aspects of electromagnetic compatibility both within the railway environment and between the railway environment and the outside.

These standards are directly referred to by the harmonized standard EN 50155, concerning the environmental stresses typical of the railway environment. This together with the norm EN 45545, concerning fire behavior, are the main specific standards of the railway environment to which electronic equipment installed on trains, subways and trams must comply.

The EN 50121 family of standards is divided into 6 parts that cover different areas:

  • EN 50121-1 General information
  • EN 50121-2 Emission of the entire railway system to the external environment
  • EN 50121-3-1 Rolling stock — Train and complete vehicle
  • EN 50121-3-2 Rolling stock — Equipment
  • EN 50121-4 Emission and immunity of signaling and telecommunications equipment
  • EN 50121-5 Emissions and immunity of fixed power supply equipment and systems

The EN 50121-3-2 standard applies to electrical and electronic equipment installed on board, which takes into consideration both the internal environment of the railway infrastructure and the external environment.

The standard also considers any interference generated by portable radio transmitters used on board, such as walkie-talkies.

The objective of the standard is to define the limits and test methods to satisfy the emissions and immunity requirements in relation to conducted and radiated disturbances.

The emission requirements aim to ensure that the disturbances generated by the equipment during its normal operation do not exceed a level that prevents other equipment from functioning properly.

Likewise, immunity requirements aim to ensure that devices installed on board are not too susceptible to disturbances generated by other equipment.

The testing of railway equipment can be complex for certain parts, which is why it is best to rely on an expert laboratory such as Sicom Testing which, thanks to its many years of experience in carrying out the tests provided for in the standards EN 50155 and EN 45545 , can provide all the support necessary to evaluate and verify the electromagnetic compatibility aspects of these products.

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2 thoughts on “La norma armonizzata EN 50121-3-2”

  1. Hi, I'm a USTIF official, I have to approve with NOT the installation of magnetic validators on some tram cars.
    How do you recommend I proceed?
    Thank you

    • Good morning.
      In this case it is necessary to consult the indications of a notified body for the railway interoperability directive. Preferably the same one who has already certified the tram.
      Greetings from Sicom Testing


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