Electrical Requirements For EN50155

EN50155 standard “Railway Applications Electronic Equipment Used on Rolling Stock” is one of the two most used standards for DC conversion Equipment in Railway application. This European Standard applies to all electronic equipment for control, regulation, protection, diagnosis, energy supply, etc. installed on rail vehicles.RIA12 from UK, “General Specification for Protection of Traction and Rolling Stock Equipment from Transients and Surge in DC Control Systems” is also well-known as a point of reference for DC system designs in Railway application. Even though those standards are quite similar, the RIA12 requires higher input voltage than EN50155.

Operating Voltage Ranges

There are several battery systems in railway application.Those are 24, 36, 48, 72, 96, 110VDC but the input voltage is not stable when the system is operating. Equipment powered directly from batteries with no voltage stabilizing device must function properly with input voltages that range from 0.7VN to 1.25VN during normal operation. The equipment must also withstand input voltage drops of 0.6(VN) for 100 ms and overvoltage surges of 1.4VN for one second that may occur during startup.

Nominal Inputs (VN) Permanent Input Ranges (0.7VN – 1.25VN)

Nominal Inputs (VN) Permanent Input Ranges (0.7VN – 1.25VN)Transients
Low (0.1s) 0.6VNHigh (1s) 1.4VN
24V16.6 – 30V14.4V33.6V
37.5V26 – 47V22.5V52.5V
48V33.6 – 60V28.8V67.2V
72V50.4 – 90V43.2V100.8V
96V67.2 – 120V57.6V134.4V
110V77 – 137.5V66V154V

Isolation Voltage

According to EN50155, there is a basic requirement for isolation voltage between input and output.Where Un is Battery System

Un<72: 500VAC, 72VDC<=Un <125VDC: 1000VAC, 125VDC<=Un <315VDC: 1500VAC

Electromagnetic Interference Requirements

Railway electronic systems are subjected to different level of electromagnetic interference requirements. Helios’ railway DC/DC Converters and DC/AC Inverters meet the following standards.

ParameterBasic StandardConditionsPerformance Criteria
ESDEN61000-4-2Air ± 8kVB
Contact ± 8kV
Radiated ImmunityEN61000-4-320V/mA
Fast TransientEN61000-4-4± 2kVA
SurgeEN61000-4-5Line-Gnd: ± 2kVB
Line-Line: ± 1kV
Conducted ImmunityEN61000-4-610V/mA

Operating Temperature Range

According to the table shown as below required by EN50155, the power module needs to be designed to meet requiments of sorrounding environment and make sure temperature of the power module under the maximum rating.

Operating Temp. ClassesAmbient Temp Outsite vehicleInternal Cubicle Temp.Internal Cubicle Overtemp.
(10 min.)
Air Temp. Around PCB
T1-25 +40ºC-25 / +55ºC+15ºC-25 / +70ºC
T2-40 +35ºC-40 / +55ºC+15ºC-40 / +70ºC
T3-25 +45ºC-25 / +70ºC+15ºC-25 / +85ºC
TX-40 +50ºC-40 / +70ºC+15ºC-40 / +85ºC

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 in vented 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 aluminum packages. These enclosures also protect internal electronic boards from condensation and the ingress of oil, salt, sand, insects and other environmental contaminants