What is EN50155?
EN50155 is the international standard for electronic equipment used on rolling stock. The standard specifies the conditions for operation, design, construction and testing of electronic equipment in order for it to be deemed competent and reliable for railway service. EN50155 applies to electronic equipment installed on trains, locomotives, wagons, carriages and high-rail vehicles.
Equipment rated to EN50155 include radios, train management systems, digital speed displays, in-cab signalling systems and automatic train control systems, passenger display systems, tacho-generators, end of train devices, brake computers, driver alertness monitoring systems and event recorders.
What testing is performed?
Type approval to EN50155 includes electromagnetic compatibility (EMC), shock and vibration, and climatic testing.
The scope and depth of testing depends on the type of equipment being designed, the service conditions it will encounter, and what requirements have specified by the client. The EN50155 standard specifies the normal, or most common, tests to be performed, and provides references to other EN standards which dictate exactly how a test is performed. These low level standards are used by your test facility to configure their equipment. There are over 20 lower level standards that are referenced in EN50155.
Navigating EN50155 and the lower lever standards takes time and requires careful attention to referencing between different standards. In our guide book, EN50155 Made Easy, we explain the relationship between EN50155 and the lower level standards. The EN50155 Made Easy guide book is a must for anyone designing or testing electronic equipment for railway applications.
Electromagnetic Compatibility Testing
In order for a piece of equipment to be deemed suitable for railway service it must not emit unwanted electromagnetic energy that may interfere with the normal operation of other devices. Similarly, it must operate reliably in the midst of the electromagnetic noise that can be expected in a rail vehicle.
EN50155 specifies a series of tests that need to be performed on the equipment to measure the electromagnetic energy it radiates. The tests also confirm it is able to function reliably while subject to different forms of electromagnetic interference. These tests include radiated and conducted electromagnetic emissions, radiated and conducted immunity and electrostatic discharge (ESD). There are also a series of tests on the power supply input to test against surges, ripple and interruptions in the supply voltage.
Vibration, Shock and Bump Testing
Equipment installed on railway vehicles is exposed to continuous vibration and shock in an extremely harsh environment. Over a full service lifetime in these conditions can result in various equipment failures, such as insulation rubbing off wires and metal fatigue in brackets. In rare circumstances resonant frequencies can interfere with the functionality of microprocessor based electronics.
Larger pieces of equipment may be designed to sit on isolation mounts which dampen the affects of shock and vibration. This is achieved by cushioning the equipment on rubber feet. The consequence of this approach is that the equipment is allowed to sway under vibration, and can be at risk of exceeding the installation envelope and hitting surrounding equipment or walls. Measurements can be performed during vibration, shock and bump testing to determine how much sway space is required.
Climatic Testing
Equipment installed in railway vehicles may be exposed to high and low temperature conditions, high humidity, altitude, salt mist and ingress of dust and fluids. Variations in temperature can cause power supplies to fail or microprocessors to reset. Altitude can cause sealed enclosures, such as LCD screens, to crack. Salt mist and the ingress of dusts and fluids can penetrate enclosures and harm electronic components and circuit boards.
EN50155 specifies a range of tests which confirm correct functionality is maintained while the equipment is exposed to these conditions. The tests also assess the equipments mechanical design, such as thermal conduction and convection, and ingress protection form harmful substances such as liquids or dust.
Where to get EN50155
If you need to purchase a copy of EN50155, we recommend using either BSI Shop (www.shop.bsigroup.com) or SAI Global (www.saiglobal.com). These sites will also give you access to the lower level standards referenced throughout EN50155.
Further reading
The EN50155 Made Easy guide book, available from this website, is a must for anyone designing or testing electronic equipment for railway applications.
The guide book provides detailed explanations of all of the tests involved in each area outlined above. It references the specific lower level EN standards and assists you in generating test specifications and test procedures appropriate to your piece of rail equipment.
