Power Supply for CompactPCI PlusIO in Accordance with EN 50155

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    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; this has already been explained in an earlier article.

    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 not only cover all imaginable environmental conditions, but also describe how to meet fluctuations of the supply voltage and its transients:


    For the power supply in railway equipment additional requirements apply, such as:


    • In a system with 110 VDC the input voltage can fluctuate between 77 and 137.5 VDC without any temporal limit. In addition, the input voltage may vary extremely in a range from 66 to 154 VDC for a period of 0.1 s. In order to meet these extraordinary requirements for the input voltage range, only power supplies can be used which have been especially designed for use in trains. These power supplies are available for CompactPCI and thus also for CompactPCI PlusIO as COTS products.


    • Ripple of the input voltage: The direct input voltage from a one-phase or three-phase-generator is more or less unsmoothed. It can contain significant ripples which may amount to 15\% of the average voltage and are not kept away from the input filters. In addition the control circuits of the power supply have to be quick enough to smooth the fluctuations of the input voltage so that they do not occur at the output.


    • Input voltage surges: The EN 50155 defines the relation between surge voltage, duration and source impedance, and higher voltages, which occur for a shorter time and with a higher source impedance. For 110 V, for example, a test with a 1.4-fold overvoltage (154 VDC) for 1 s with a source impedance of 1 Ohm is prescribed.

    Reliability and long availability of the electronics is decisive for railway applications. CompactPCI PlusIO is based on CompactPCI and its proven mechanics. 3U systems are especially suited for applications in the railway market as they are extremely space-saving and cost-effective. CompactPCI PlusIO supports modern serial connections like PCI Express, USB, SATA and Ethernet and guarantees availability of the components for the next decade. Computer systems for the railway standard should be compatible to PICMG 2.30.