Built for the Rails: What EN 50155 Really Demands from Your Devices OCTOBER, 2025

The railway industry operates in one of the most demanding environments for electronic equipment. To ensure reliability, safety, and long-term performance, the European standard EN 50155 provides a unified framework governing the design, testing, and application of electronic systems used in rolling stock. This standard covers everything from power input and environmental stress to electromagnetic compatibility. Understanding EN 50155 is critical for manufacturers, system integrators, and operators who supply or implement electronic devices in railway applications. EN 50155 specifies the conditions and requirements for electronic equipment used on railway vehicles. It encompasses several aspects of equipment performance over its entire lifecycle, including:

• Electrical power characteristics
• Environmental and mechanical stress
• Thermal behavior
• Electromagnetic compatibility (EMC)
• Reliability and expected service life
• Conformity to safety and functional criteria

Unlike general industrial standards, EN 50155 addresses the unique challenges of trainborne systems. Devices such as Ethernet switches, sensors, gateways, passenger information systems, and control units must perform flawlessly despite unpredictable conditions like voltage fluctuations, shock, vibration, extreme temperatures, and electromagnetic interference.

Power Distribution System on Railway – Voltage Requirements

One of the most critical requirements in EN 50155 relates to the power supply environment. Railway vehicles use onboard power distribution systems that can vary based on regional and operational specifications. Standard nominal input voltages include 24 VDC, 36 VDC, 48 VDC, 72 VDC, 96 VDC, and 110 VDC. However, electronic devices must handle much more than just nominal voltage. EN 50155 defines specific test conditions to simulate real-world power conditions. These include:

• Voltage range tests: Equipment must tolerate operating voltages from 0.7 to 1.25 times the nominal value.
• Surge and transient tests: Devices are exposed to temporary voltage surges and dips to ensure performance during sudden power disruptions, braking energy feedback, or pantograph contact issues.
• Power interruption tests: Equipment is tested to ensure it can ride through or recover from temporary interruptions without failure.

This ensures that electronic systems do not malfunction when trains start, stop, switch power sources, or experience momentary losses in supply.

Reliability Conditions – Shock, Vibration, and Stress

Railway vehicles are exposed to continuous movement, making mechanical durability crucial. EN 50155 references EN 61373, which defines test procedures for shock and vibration resistance. Devices are tested across three categories, depending on where they are installed:

• Category 1: Body-mounted equipment
• Category 2: Bogie-mounted equipment
• Category 3: Axle- or wheel-mounted equipment

Tests simulate long-term stress and sudden impacts from braking, track irregularities, switch changes, and coupling operations. Equipment must remain electrically and mechanically stable without structural failure or loss of function. Other reliability-related stress factors include:

• Humidity and condensation effects
• Corrosion resistance
• Thermal cycling
• Ingress protection (IP) against dust and moisture

Devices must maintain performance over a service life often exceeding 20–30 years, with minimal maintenance and downtime.

Environmental Conditions – Climatic Considerations

Temperature tolerance is a key part of EN 50155 compliance. Electronic devices on trains must operate reliably across wide temperature ranges, depending on the class assigned:

• Class T1: –25°C to +70°C
• Class T2: –40°C to +70°C
• Class TX: –40°C to +85°C

Short-term temperature peaks above the specified range (+15°C for 10 minutes) are also considered. The standard also considers:

• Humidity levels up to 95%
• Resistance to condensation
• Cooling and ventilation requirements
• Altitude and pressure variations

Manufacturers typically employ conformal coating, sealed enclosures, and thermal management designs to meet these conditions.

Electromagnetic Conditions – EMC Compliance

Railway environments generate significant electromagnetic interference (EMI) from traction motors, transformers, communication equipment, and switching components. EN 50155 requires compliance with EMC standards specified in EN 50121-3-2 and related directives. Key goals include:

• Emission control: Ensuring devices do not radiate interference that affects other systems such as braking or signaling
• Immunity requirements: Verifying that external electromagnetic disturbances do not impair functionality
• Electrostatic discharge (ESD) resistance
• Surge and burst immunity

Equipment is tested for both conducted and radiated emissions/immunity, often in specialized EMC chambers. This ensures that electronic systems can coexist without degrading performance or endangering railway safety.

Why EN 50155 Matters

Compliance with EN 50155 ensures:

• Safety

  Fail-safe performance under extreme conditions

• Reliability

  Long-term operation with minimal downtime

• Compatibility

  Smooth integration with railway networks and third-party equipment

• Reduced maintenance costs

  Longer service intervals and predictable performance

• Global acceptance

  Recognition across Europe and other regions that adapt EN 50155 as part of procurement requirements

For manufacturers, certification demonstrates credibility and market readiness. For railway operators, EN 50155 compliance reduces infrastructure risk and ensures dependable service.

EN 50155 is more than a technical checklist—it is a comprehensive guideline engineered to guarantee the safety, durability, and interoperability of electronic equipment in demanding railway environments. It covers power fluctuations, electromagnetic interference, climatic challenges, and mechanical stress, ensuring that products can withstand real-world railway conditions. Whether designing power systems, computing platforms, or control devices, adhering to EN 50155 is essential to delivering dependable performance on today’s modern rail networks.