Apart from the large number of standards, one of the specificities of the railway sector is the fact that many applications have very specific requirements in terms of housings and connectors, often resulting in products that are dedicated to a particular customer. While the trend is towards the standardization of card modules such as DC/DC converters shown in figure 3, for more complex products such as locomotive starter converters or decentralized battery chargers, the on-demand product remains the norm.
This requires a development capacity geared towards these products and a high degree of flexibility in production. In fact, despite a growing market (+6% per year), the volumes of power supplies used in the railway sector remain modest compared to the millions of units consumed in the telecommunications sector, requiring manufacturers such as Powerbox to adapt their production tools to specific demands.
Designing power for long life time
The majority of customers in the railway sector require a 30 years or more availability for some critical equipment. This means that during development this service life must be taken into account, as well as the possibility of replacement for certain components such as electrolytic capacitors affected by aging during life time. All this must be considered during the design. Knowing that railway power supplies can be exposed to severe environmental effects such as temperature variations or shock and vibration during the life of the product, equipment manufacturers include “components refreshment and re-calibration” in their specifications. It is common to see products delivered more than 15 years ago return to the workshop for review and updating. This practice is very specific to the railway sector and has a strong influence on the way feeds are designed.
Indeed, a 30-year lifespan obliges developers to select components with a low risk of obsolescence but also to design the product for possible upgrade during its useful life. This adds a level of complexity but also limits the introduction of new technologies. As mentioned above, engineers in charge of the development of tomorrow's railway systems want to integrate new technologies, but the limited knowledge of their lifecycle and sustainability raises questions about the level of risk associated with their introduction. This is a topical issue that is being debated within the railway community which on one hand wants to modernize its power supply systems to make them more energy-efficient and better connected, and on the other hand want to guarantee a risk-free sustainability.