What to take into account when choosing power supplies for railway?

Why the train?

Just like the airplane, rail transport (train, tram, metro) is a frequently used means of transport for both goods and people. It is estimated that about 1.8 billion people worldwide take the train every year.

Thanks to the investments that have already been made in recent years in the electrification of rail transport, this mode of transport is one of the least polluting of all transport options.

The image below shows means of transport and their CO2 emissions. The train scores well in terms of CO2 emissions compared to many other, more polluting means of transport.

Technologies on the train

Reliability and safety are key in rail transport.

To ensure a qualitative and smooth operation of rail transport, many specific standards and requirements have to be met. Think of electrical requirements, but also of compensation in shock and vibration, temperature range, EMC/EMI, lifespan and reliability (MTBF), design, …

The most well-known electrical component of the train are the electric motors that are used to move the train. The operating voltage of these motors varies from region to region, but by European standard the 1.5kVDC, 3.3kVDC, 15kVAC and 25kVAC power lines are the most common.

In addition to this electrical application, there are many other things in the train that operate on a different voltage. Think, for example, of control systems, automatic braking systems, operating systems, radio and public address systems, displays, lighting, passenger sockets, etc.

Various low voltages are still needed on board to feed all these systems. These are mainly 24VDC, 72VDC and 110VDC. 48VDC and 96VDC are less common on board.

Based on this, it can be stated that the absolute voltage range (including margin) on the train is between 12VDC and 160VDC.

These different voltages are generated on board by different DC/DC or DC/AC converters.

Railway approved converters are not only needed in the train, tram or metro, but they also come in handy next to the track. Think of converters for control cabinets, signalling, telemetry, level crossings, and switch controls that are also subject to shock and vibration from passing trains or trams.

Our railway approved solutions

To ensure that the converters are suitable for railway applications, they must – as mentioned earlier – meet specific requirements and standards. The most common standards within railway are:

• IEC45545-2 (Fire protection requirements)
• IEC50121-3-2 (EMC)
• IEC50155 (Electronic equipment used on rolling stock)
• IEC50163 (Traction supply voltage)
• IEC60950-1 IEC63268-1 (Safety)
• IEC61000-4-5 (Surge immunity)
• IEC61373 (Shock and vibration)
• RIA 12 (Surge protection (3.5VN 20ms))
• RIA 13 and RIA 20 (Mechanical standards)

In addition to these standards, the design of the converters is also very important. For example, closed frame converters are available in DIN-rail and 19”. Another common construction form is on PCB: these converters are especially suitable for lower powers and allow for very compact work.

With Elipse we have more than 35 years of experience within the railway market in the Benelux. Thanks to our experience, we quickly recognize which solution best suits your project.

On the one hand, we can offer converters that are in stock as standard, and on the other hand we can develop fully customized converter solutions. Several of our partners specialize in power supplies tailored to the railway sector. Below an overview.

PULS railway power supplies

The DIN-RAILway power supplies from PULS represent a new range of railway power supplies whose concept has already been proven in tens of thousands of industry applications worldwide. What distinguishes the PULS DIN-RAILway power supplies is the extremely simple DIN-rail fixation.

A complete range of 1- to 3- phase units and DC/DC converters are currently available, all of which can be mounted on DIN rails and are approved to comply with the common railway standards.

The units are: convection cooled, operational down to -40°C; equipped with vibration-compensating spring clamp terminals, conformal coated, extremely lightweight in a compact housing and exhibit the highest level of efficiency. PULS DIN-Railway customers also receive the benefits of the logistical resources of a large-scale manufacturer.

The most used DC/DC converters in railway applications from PULS are the QS5.241-60 (100W), CP10.241-60 (200W), QS10.241-60 (200W) and CPS20.241-60 (400W).

Premium railway power supplies

Premium PSU has been providing reliable power supply solutions for the main companies of the railway sector since its early days. This path began in the early 80s with a special retro fit design for the subway of Madrid (a 300 W DC/DC converter with dual output) and continues to this day. Premium PSU is outstanding in developing and manufacturing limited series of completely custom-made products.

A few examples of Premium DC/DC converters, from 50W to 10 kW, used for railway are CTS-120 (100-140W) and ODS-1500 (1PH 500W).

Gaïa railway power supplies

Gaia Converter is a global leader in field proven high reliability DC power modules on PCB.

With over 3500 part numbers, its DC/DC Converter, PFC Front End and related input protection product lines offer all necessary building bricks for complete modular High Reliability power supply architectures, from 4W to 350W or more.

Fully equipped with thorough processes and tools, Gaia Converter’s advanced design and development computer aided capabilities include :

• Circuit behavior simulation
• Thermal management
• Advanced packaging techniques
• Proprietary magnetic and ASIC design
• Environmental test
• Reliability evaluation

Through high standard processes and automated manufacturing capabilities, Gaia Converter delivers high quality products in a timely manner for the long run.

To cope with the needed requirements, they propose typical off-the-shelf modular power architecture :

• LGDS series : essential functions such as energetic spike protections and EMI filters according to EN50155, RIA12, IEC571 are provided by standard “limiter” front-end products
• MGDI series : for the heart of the power system, Gaia Converter offers a complete series of low profile, cost-effective and high performance DC/DC modules that come in multiple combinations of input voltages, output possibilities and power ratings