Input Voltage Range
For historical reasons, a large number of different supply voltages are used in railway applications. The most common ratings are 24VDC, 48VDC, 72VDC, 96VDC and 110VDC.
The latest version of EN50155 defines seven different standardized DC voltages, although 110VDC is the most commonly used on trains. The 24V thru 48V is often used on light railways, trams and trolley buses.
In order to meet these requirements for nominal input voltages, railway application developers opt for 4:1 converters such as the RP20-FR and RP40-FR series from RECOM, as they cover the entire nominal input voltage range with 3 different converter models only.
Nominal Input Voltage |
EN50155 |
RECOM RPxx-FR Serie |
Input Range |
Min. Input (0,1s) |
Max. Input (1s) |
Input Range |
Min. Input |
Max. Input (1s) |
24V |
16.8-30V |
14.4V |
33.6V |
9-36V |
9V |
50V |
48V |
33.6-60V |
28.8V |
67.2V |
18-75V |
18V |
100V |
72V |
50.4-90V |
43.2V |
100.8V |
43-160V |
43V |
170V |
96V |
67.2-120V |
57.6V |
134.4V |
43-160V |
43V |
170V |
110V |
77-137.5V |
66V |
154V |
43-160V |
43V |
170V |
Fig.: EN50155 certified DC / DC converters must tolerate strong input voltage fluctuations. With the RPxx-FR series from Recom, the entire range from 24 to 110 V can be covered with three converter types. The RPA100H and RPA200H even cover the entire voltage range with only one module
EN50155 states that the nominal input voltage may fluctuate between 0.7 and 1.25 times the rated voltage, and permits short-term deviations between 0.6 and 1.4 times that value. This means that a 48V DC/DC converter must cater for a voltage range of 28.8V to 67.2V.
Until recently, there was a consensus that 4:1 converters had reached their limits with regard to efficiency and cost-effectiveness. This is now all changing with the latest 100W and 200W DC/DC converters from RECOM. The RPA100H and RPA200H feature a broad 10:1 input to cover all common voltage ratings in one module.