Our project installs computers in railway carriages and requires EN 50155. What does that standard demand from the machine?

EN 50155 is the standard for electronic equipment on railway rolling stock. When a tender calls for it, check the following on the machine. Power: nominal on-board voltages are typically 24, 36, 48, 72 or 110 VDC, and the standard requires tolerance of fluctuations and short interruptions. The input range must match the train's supply, not just 24 V. Temperature: the standard defines several classes (OT1 to OT6); the tender will state the required class, commonly -25…70 °C. Shock, vibration and EMC: usually paired with IEC 61373 for shock and vibration and EN 50121-3-2 for electromagnetic compatibility. Connectors: prefer screw-locking M12 for LAN and power, and conformal coating on the boards against humidity. Most important: request the certificate or test report for the exact model number, because not every model within a product line qualifies.