RWY259 250W-300W

DC/DC Converter Railway Applications

This fully encapsulated, rugged, railway quality DC/DC converter uses field-proven technology to generate between 250 ~ 300W, depending on the input/output combination required. It is a mature design with a track record in numerous applications. The unit is entirely potted with a thermally conductive MILgrade silicon rubber compound to ensure immunity to shock, vibration and humidity.

It is conduction-cooled via a base plate to a heatsinking surface. Low component count, large design headrooms, and the use of components with established reliability result in a high MTBF. The unit meets the requirements of EN50155 for electronic equipment used on rolling stock.

Main Features

  • Designed to rail standards EN50155 & EN50121
  • 250 ~ 300 watts depending on input/output combination
  • Fully potted with thermally conductive MIL-Spec silicon rubber compound
  • Rugged design for on-board train applications
  • Wide input voltage range
  • Convection / Conduction cooled: No fans
  • Fully isolated input-output 3000VDC
  • Overvoltage protection
  • Overload and short circuit protection
  • MTBF > 150,000hrs
  • Specials input/output combinations on request

Rugged Mechanical Designs

Helios power supplies are ruggedly constructed and can be customized for specific mechanical requirements. Standard mechanical packages and ruggedization options include:

  • Chassis and wall-mountable units invented conduction/convection or fan-cooled enclosures
  • DIN-rail and open-frame format available for many designs
  • Plug-in (Eurocard) format for modular power systems in 19 inch or 23-inch racks
  • Conformal coating and ruggedizing are standard
  • Full encapsulation (potting) in a thermally conductive MIL-grade silicon rubber compound with UL94V-0 flammability rating for immunity to high levels of shock and vibration, humidity, moisture, dust, salt, oil, insects and other contaminants
  • Enclosure in rugged, IP66- or IP67-rated waterproof, dustproof and explosion-proof die-cast aluminium packages. These enclosures also protect internal electronic boards from condensation and the ingress of oil, salt, sand, insects and other environmental contaminants
  • Custom connections
  • Portable DC Power Supplies


ModelStandard OutputsPower (W)
RWY259  5V


Operating input voltage range24VDC   ( 14.4 ~ 34 )
36VDC   ( 22 ~ 51 )
48VDC   ( 20 ~ 67)
72VDC   ( 43 ~ 101)
96VDC   ( 58 ~ 135)
110VDC   ( 66 ~ 154)
Input ProtectionReverse polarity protection.Inrush current limiting Lower voltage than specified will not damage unit
Output VoltageSee  table
Regulation±1% Line / Load combined
Operating Temp: -40ºC to +70ºC cold plate temperature
EfficiencyModel dependent , typically 80-90%
Dynamic ResponseMax ±5% diviation for 10% – 50% load step wuth 1msec recovery
MTBF>150,000 hrs

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