What is EN 50155? The Complete Guide to Electronic Equipment on Rolling Stock

EN 50155 is the international standard that governs electronic equipment used on rolling stock. Whether it is a simple passenger information display, a complex TCMS (Train Control and Management System), or advanced LiDAR sensors, every electronic device on a train must be EN 50155 certified.

Without this certification, hardware cannot guarantee safety or reliability in the harsh railway environment.

1. Why is the Railway Environment so Harsh?

Unlike a server room in an office, a train is a moving, vibrating, high-voltage environment. Equipment faces specific challenges:

• Rolling Stock Vibration: The interaction between wheels, Bogies, and the track generates constant mechanical stress.
• Power Fluctuation: The voltage from the Catenary (OLE) or Third Rail is rarely stable. It spikes when the train accelerates and drops during Regenerative Braking.
• Temperature Extremes: Devices must work in freezing tunnels and overheating electrical cabinets.

2. Key Testing Areas of EN 50155

A. Shock and Vibration (IEC 61373)

Electronics are mounted on the train body or directly on the Bogie. They must survive the physical impact of shunting operations and the constant vibration of running on ballast or Slab Track. The standard defines three categories:

• Class A: Body mounted (Least vibration).
• Class B: Body mounted (Directly on structure).
• Class Axle: Bogie mounted (Extreme vibration – rare for standard electronics).

B. Temperature Classes

The equipment must start up and operate in defined temperature ranges. This is critical for systems like ETCS signaling units which control train safety.

C. Power Supply & EMC

Trains run on various voltages (750V DC, 1500V DC, 25kV AC). The electronics connect to a battery or auxiliary converter. EN 50155 requires devices to withstand:

• Voltage Dips: 0.6 times the nominal voltage for 100ms.
• Surges: 1.4 times the nominal voltage for 1 second.
• EMC (Electromagnetic Compatibility): Ensuring the device doesn’t interfere with CBTC radios or track circuits.

3. Modern Applications: EN 50155 in the Age of AI

With the rise of “Smart Trains,” the standard is more relevant than ever. New technologies require ruggedized certification:

• LiDAR & Cameras: Perception sensors for autonomous driving must be TX class rated to survive on the train roof.
• IoT Gateways: Devices sending real-time data for Predictive Maintenance (like Ultrasonic Testing data) need robust power protection.
• Passenger Wi-Fi: High-bandwidth routers must endure the vibration of high-speed travel.

Conclusion

EN 50155 is not just paperwork; it is the engineering benchmark for railway safety. Whether designing a new High-Speed Rail trainset or retrofitting a metro line, compliance ensures that critical systems won’t fail when it matters most.