EN 50155: A Critical Standard for Power Supply Design in Railway Systems

10th April 2024

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In transportation, particularly within railway systems, the adherence to technical standards is non-negotiable for the development of power supply products that are both safe and reliable. Among these, EN 50155 emerges as a pivotal European standard, governing the electronic equipment utilized in rolling stock. This standard, crafted by the European Committee for Electrotechnical Standardization (CENELEC), transcends its European origins to address the global railway market’s needs, setting the benchmark for power supply design and testing in this sector.

Safety and Reliability in Modern Rail Networks

The integrity of power distribution systems in trains is paramount, necessitating compliance with rigorous standards, with EN 50155 standing out for its comprehensive coverage. This standard is applicable to a wide array of electronic equipment on trains, spanning power supplies, ensuring their safety and reliability across diverse railway applications. As trains evolve, incorporating advanced engineering and enhanced passenger amenities such as onboard Wi-Fi and sophisticated climate controls, EN 50155’s role becomes increasingly vital, necessitating periodic updates to align with technological advancements and complex electrical demands.


accessibility &
Passenger Convenience


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EN50155 Standard for accessibility and passenger convenience icon
EN50155 Standard for wayside
EN50155 Standard for safety
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Battery Charging

Driving aid

Brake systems

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Comprehensive Scope of EN 50155 Standard

The EN 50155 standard delineates requirements for electronic equipment involved in control, regulation, protection, diagnostics, and energy supply within rolling stock. It addresses various aspects including operating conditions, design, documentation, testing, integration, and software considerations for power supplies and converters. These components are crucial for delivering stable and clean power across the electronics spectrum in modern rail systems. The standard emphasizes key factors such as voltage variation, temperature extremes, shock, vibration, electromagnetic compatibility, and overall reliability. 

Interconnected Standards and Updates

EN 50155 does not stand in isolation but references additional standards that tackle specific challenges, including fire safety (EN 45545-1), electromagnetic emissions and immunity (EN 50121-3-2), and shock and vibration resistance (EN 61373). These referenced standards ensure a holistic approach to safety and performance in railway power supply design.

Since its initial publication in 1995, EN 50155 has undergone several revisions to keep pace with the evolving landscape of power supply technology and railway safety. Noteworthy updates have introduced new testing categories, enhanced safety management requirements, and adjustments to operating temperature classes and equipment life expectancy, reflecting the standard’s adaptability to changing technological and safety paradigms.

EN50155 Standard for timeline of revisions
Figure 2: Timeline of updates and revisions to EN 50155.

EN 50155's Impact on Power Supply Design

The standard’s relevance extends to various facets of power supply design for railway applications, addressing supply voltage characteristics, environmental conditions, shock and vibration tolerance, electromagnetic compliance, and performance reliability. These elements are critical for ensuring that power supplies can withstand the rigorous demands of railway environments, contributing to the safety and efficiency of rail transport.

Guidance for Compliance & Innovation

For manufacturers and designers of railway power supplies, EN 50155 serves as an essential guide, ensuring that products not only meet stringent performance and safety criteria but also cater to the specific needs of the railway industry. Companies like Bel, through their Melcher brand, exemplify the commitment to designing and manufacturing power supplies that comply with EN 50155 standard, offering customized solutions to meet the unique requirements of railway applications. 

Related Content

A new version of the defacto railway standard EN50155, for electronic equipment, has hit the streets on October 2017. Our review below helps provide a quick overview of some of the key differences between the 2007 and 2017 versions.


In conclusion, the EN 50155 standard stands as a cornerstone standard for the design and development of power supply systems in the railway sector, embodying the principles of safety, reliability, and technological advancement. Its comprehensive scope and periodic updates ensure that railway power supplies keep pace with the evolving demands of modern rail systems, underpinning the safe and efficient operation of trains worldwide.

Bel-Power, with its extensive portfolio of power supply solutions and its collaboration with Relec Electronics in the UK, remains a definition of excellence in the railway sector. Their dedication to safety, dependability, and forward-thinking positions them as a crucial partner in the of railway industry.  

GET IN TOUCH TODAY – 01929 555700

At Relec Electronics, we are committed to empowering your applications with the right power conversion solutions. Leveraging our extensive knowledge and experience, we guide you through the selection process, ensuring that you have all the information you need to make the best choice for your specific needs.

In the ever-evolving world of power electronics, having a trusted partner like Relec Electronics by your side ensures that you are equipped with the right tools and knowledge to navigate the complexities of power conversion, driving your applications to new heights of performance and reliability. 

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