Harsh Requirements for CompactPCI PlusIO in Accordance with EN 50155

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    Author: Manfred Schmitz, Chief Technical Officer, MEN Mikro Elektronik



    CompactPCI PlusIO PICMG 2.30 is based on the proven mechanics of CompactPCI PICMG 2.0. All PICMG 2.30 components are 100\% compatible to CompactPCI. CompactPCI is able to meet even the harsh requirements in a train, which we want to show here with the related standard as an example.


    The EN 50155 for the electronic equipment in a train aims at a functionality of 24 hours a day for 20 years, i.e. about 175,000 hours. This is achieved by defining requirements which have to be met in all imaginable environmental conditions, including the operating temperature range, shock and vibration, fog and salt, etc.:


    • Ambient temperature: The EN 50155 requires up to -40..+85 °C. In addition it defines a thermal shock of 3°C/s as a requirement when passing through a tunnel. Because of the extreme temperatures, the thermal increase rates and the humidity, the components and the PCBs have to resist condensation which occurs if the temperature rises from values below zero degrees.
    • Humidity: The EN 50155 prescribes general rules: Relative humidity of an average 75\%, followed by 30 consecutive days with a humidity of an average 95\%. This means that in most cases the electronic equipment requires waterproof housings or coated assemblies.
    • Pollution: Depending on the accommodation of the equipment it can be subject to pollution: Conductive dust, oil mist, spray salt and/or sulfur dioxide. Conformal coating and housings with IP protection class prevent the negative consequences.
    • Cooling: Forced air cooling should be avoided because it requires increased maintenance work. Pure convection cooling requires a suitable board and housing design.
    • EMC: Moving trains are subjected to a multitude of electromagnetic disturbances. The transient burst resistance has to be proven according to EN 50121-3-2 and EN 61000-4-4. Resistance against radio disturbances has to conform to EN 50121-3-2 and electromagnetic radiation to EN 50121-3-2. CompactPCI PlusIO is based on IEEE 1011 which includes all required shielding technologies.
    • Shock and vibration: The EN 50155 describes test methods and limit values which are defined in EN 61373. Even though the applications listed there stipulate DIN rail mounting, more stable mounting techniques, which CompactPCI offers, have to be used for high vibration environments.