Rugged High-Power Converters Meet Stringent Railway Standards

Whether on a train, track, or station, power supplies used in railway applications are regularly exposed to extremely harsh conditions, while also being expected to work accurately and reliably. The expected lifespan of these products is decades long, with extreme working conditions including heat, cold, shock & vibration, mechanical impact, and EMI—all of which can cause serious damage to the electronic assemblies of power converters.

Rugged power converters that can withstand all of these harsh conditions are critical when designing railway systems. To qualify for use in railway systems, power supplies must also meet the highest standards, including for shock and vibration, fire protection, thermal, EMI/ESD, weight, and safety and reliability.

Strict Railway Standards

Today, several stringent international standards regulate railway applications. Some of these include:

• EN 50155 - Electronic equipment used on rolling stock
• EN 61373 - Shock and vibration tests
• EN 50121-3-2 - Electromagnetic Compatibility (EMC)
• EN 45545-2 - Fire Protection on Railway Vehicles

EN50155, for instance, is a well-known performance standard for electronic equipment used in rolling stock (All rail vehicles that move, including locomotives, passenger wagons, light railways, and freight trains). Besides laying down minimum requirements for the input voltage range, electrical isolation, operating temperature range, shock and vibration, humidity, and EMC, it also specifies equipment reliability and expected useful life.

In many cases, electronic equipment used on rolling stock is expected to have more than 20 years of operational life, demanding thorough environmental testing. Additionally, the EN50155 standard also mandates normal operating temperature tests as well as thermal cycling, dry heat, and damp heat tests.

EN 61373, on the other hand, specifies the requirements for testing equipment intended for use on railway vehicles which may be subject to vibrations and shock owing to the nature of the railway operational environment. EN 50121-3-2 applies to the emission and immunity aspects of EMC for electrical and electronic apparatus intended for use on railway rolling stock. To achieve the highest level of safety possible in the event of a fire, all materials used in rail vehicles must comply with the European standard EN 45545-2.

High-Power DC/DC Converters

Applying over 40 years of experience in developing and manufacturing leading standard and custom power converters, RECOM recently expanded its product portfolio of EN50155-certified power supplies. With the acquisition of the Italian power specialist Power Control Systems, RECOM now offers customized power solutions of up to 10kW for railways, alongside a broad range of AC/DC and DC/DC converters.

Several different supply voltages have emerged for DC/DC converters used in railway systems in the last few decades. The standard voltage ratings are 24VDC, 36VDC, 48VDC, 72VDC, 96VDC, and 110VDC. The latest version of EN50155 defines seven different standardized DC voltages, although 110VDC is most common for long distance trains and the 24VDC through 48VDC is more typical on light railways, trams, and trolleys.

To meet the requirements for nominal 24, 48, or 110VDC input voltages, many railway application developers opt for 4:1 converters, such as the RP20-FR and RP40-FR series, as they cover the nominal input voltage range including transients, with three different input voltage versions. Recent improvements at RECOM have opened new doors for railway designers needing to cover a wider range of input voltage with only one converter type.

The company’s latest 100W and 200W DC/DC converters from the RPA100H and RPA200H families feature a broad 10:1 input range to cover all common voltage ratings in one module. With ultra-wide input from 14.4VDC to 156VDC, these DC/DC converters can be considered for any railway design without worrying about voltage tolerances, voltage dips, or the local supply voltage.

RECOM also offers isolated and regulated 12V or 24VDC output with consistently high efficiency of up to 90% over the entire input voltage and load range. Utilizing a metal baseplate, these converters operate over a wide temperature range, from -40°C to +97°C.

The RP40Q-RUW and RP60Q-RUW series go beyond the current ultra-wide input to accept 12:1 input range, from 14 to 185VDC, offering designers even more options. These converters, housed in a standard quarter-brick case, are fitted with threaded inserts for secure mounting in high shock and vibration environments. Additionally, they provide reinforced isolation at 3VDC, regulated 5VDC, 12VDC, 15VDC, 24VDC, and 48VDC output with sense and trim pins. They are CE marked, offer EN50155 and EN45545-2 certification, and come with a three-year warranty.

RECOM's expanded portfolio of DC/DC converters from 8W to 240W for the railway industry offers the broadest range of EN50155 certified products on the market. These railway-certified series are housed in compact case sizes to deliver a power density of up to 4.5W/cm³, one of the highest available today. RECOM has also developed an RMD plug-and-play series for higher power railway applications, which provides 150W to 500W of output power with five input ranges covering 14.4V to 170VDC, tested to railway standard EN 50155 and ready to go as complete solutions.

AC/DC and DC/AC Inverters

In the AC/DC arena, RECOM and its subsidiary Power Control Systems have developed three-phase AC input battery chargers with active power factor correction (PFC) and railway standard compliance. Available with ratings of 3.2kW (SA3200 series) and 5kW (SA5000 series), the converters can be cascaded to generate up to 20kW. The SA3200 series also operates with DC input up to 800V. Both series are available with output from 24VDC up to 110VDC (and all in between: 36/48/72/96VDC).

For applications that need AC supply, the company offers inverter families, like the ID250 series from Power Control Systems, that deliver single phase or multiphase output voltage or current with 24V, 48V, 72V, or 110VDC nominal input. Output is single-phase 200-240VAC or 50-156VAC for the 48V input version. The series complies with railway application standards and is typically used to provide power for passenger sockets or for driver consoles.

Conclusion

Around the world, as railway networks expand to serve the rising transportation needs of workers, tourists, and industry, the demand for rugged and standards compliant power supplies continues to increase.

As an experienced and leading provider of high-performance power supplies, RECOM is your reliable source for a broad range of rugged and standards compliant DC/DC and AC/DC converters and DC/AC inverters.

RECOM and its subsidiary Power Control Systems have stablished a broad portfolio of rugged EN 50155-compliant power converters, including complete turnkey solutions, for many railway applications. From low power (8W-240W) modules up to 10kW power supplies, RECOM has a range of standard and custom solutions for all your railway needs.