Transportation Converter Solutions

Transportation Converter Solutions


The safety of passengers and the compliance of railway standards is of the utmost importance in this market. Most applications demand that components must be adapted to the local environmental and operating conditions. High quality standards and continuous developments ensure that that REO is a reliable partner within this sector.

To guarantee compliance with railway norms, standards and the classification of Ingress Protection the following methods are used:

  • In-house testing laboratories
  • Shock and vibration tests
  • Cooperation only with selected suppliers
  • FEM analysis for the simulation of environmental influences

For railway technology REO offers inter alia:

  • NTT BW – Braking, smoothing and filter resistors
  • NTT – Mains chokes, motor chokes, interference chokes, absorption circuit choke, EMC chokes, dv/dt chokes, AC/DC chokes
  • RFI filter, sinusoidal filter, harmonic filter
  • NUT – inverter transformers AC transformers, power transformer, HF transformer, current transformer, special components for energy generation
  • NPT – test chokes for load test of frequency converters
  • REOLAB mobil – mobile power supply for the railway workshop
  • REOLAB – test devices for duration and function tests

All components for the railway technology - from transformers and chokes up to filters - are developed as a standard design or in accordance with the specific requirements of our customers. Without this specific, essential requirements, no product can operate:

  • Safety: to ensure that the safety and comfort of passengers are not impaired, every component used in a train must meet the current norms and standards. Own tests and accredited testing laboratories prove the safety of our components. 
  • Weight: Intelligent methods in materials selection and FEM-calculation mean that REO components are of particularly low weight. 
  • Space : The optimal use of space, and compliance with specified mechanical and electrical requirements, form the basis of our development work. 
  • Costs: With the latest software, simulation and testing techniques, we ensure that the necessary development work is already optimally used in advance. 
  • NTT MD 953

    Liquid-cooled three-phase mains choke 8% Uk

    NTT MD 953
    • Nominal Voltage: 400 V
    • Rated current: 200 - 1200 A
    • Inductance: 0,012 - 0,074 mH

    Watercooled chokes are available are available with ingress protection ratings IP00 to IP65. REO can utilise several methods of water cooling these components. This provides controlled conduction of heat losses, ensuring that the local environment is not heated. Water cooling ensures that component temperatures are greatly reduced, reducing component stress and increasing product life. REO technology provides excellent heat distribution, preventing the emergence of so-called hot spots.

    • Winding material : Aluminum

    • Insulation class: F

    • Cooling medium: Water/Glycol (70/30 %)

    • Max. coolant inlet temperature.: 50° C

    • Flow rate: min. 3,6 l/min.

    • Pressure drop: <0,5 bar


    Typical applications

    • AFE Drives

  • LD 100

    Air choke with copper/layer winding

    LD 100
    • Rated current: 50 - 1000 A
    • Inductance: 0,2 - 8 mH

    Air chokes are particularly used where high inductive linearity is required. Due to their relatively simple mechanical structure, they are not only compact, but also very robust.

    With our expertise, the REO air chokes perform to the required standard, even in the most arduous conditions.

    • Frequency of the current: DC und AC

    • Tolerances: + 10 / - 10 %, + 5 / - 5 %

    • Taps: By default, no taps (available on request)

    • Insulation: F or H

    • Cooling method and cooling liquid according to IEC 60310: AN, AF or WF

    • Test voltage: up to 12kV 60s 50Hz, up to 25kV 1,2/50µs

    • Mounting: Suspended, vertical or horizontal

    • Mechanical strength, mechanical simulation (FEM): EN 12663

    • Shock - and vibration stress: IEC 61373 Kat. 1 Kl. B

    REO Mix & Match principle 

    With REO Mix & Match you can choose from a wide range of of options - combine the various options in order to always get the best product for your application.

    REO is able to offer different designs and winding techniques, a variety of conductor materials and structures. Depending on the specific requirements, we are able to produce an optimal solution by combining these parameters to provide the perfect solution.


    • Layer winding/Disc winding

    • Aluminium, Copper or aluminium+copper

    • Protections: Paint coating, protective coating, housing or REO Xtreme

    • Cooling fan/unit

    • Sensors: Switch NO / NC, PT100, NTC, PTC

  • Series IE modular

    closed-loop current transformers

    Series IE modular
    • Primary rated current: 500 - 2500 A
    • Umgebungstemperatur: -25... +70 °C
    • Frequency range: 50... -400 Hz

    In the case of bushing-type current transformers, the customer’s primary wire is pushed
    through the current transformer opening in the housing. The push-through opening depends
    on the size of the primary current.
    Wound primary type current transformers have a primary winding and a secondary winding.
    Both windings are applied on the closed toroidal core and are isolated from each other by
    insulation. This principle applies mainly where primary currents are small. Low-voltage current
    transformers for the proportional transformation of large currents to directly measurable
    smaller current values.

    According to: EN/IEC 61869-1/2
    Primary rated current: 500, 1000, 2500 A
    Frequency range: 50 - 400 Hz


    • Industry

    • Renewable energy sources

    • Railway engineering

    • Energy, automation and building technology

  • NTT 400

    Onboard power supply transformer

    NTT 400
    • Rated power: 1000 - 30000 VA
    • Input voltage: 3x440 V

    The REO transformer NTT 400 is designed for on-board power supplies, which are fed by the auxiliary converter. He is used to adjust the voltage and for galvanic separation of pulse-width modulated DC link voltage and the consumers of the electrical system . A corresponding sinusoidal filter must be connected between the transformer and the inverter.
    The secondary-side load of the isolation transformer can be switchgears, rotating equipment , resistive loads or semiconductor power converters.The transformers are designed for the use in vehicles with AC or DC power (in inverter mode). This guarantees that REO transformers are optimally suited to your application. Our development methods emphasize maximum useful lifetime, cost/benefit optimization and safety.

    • Power. 1 - 30 kVA

    • Rated voltage

      Rated voltage: (Normal operation): 3x440 Veff 60 Hz
      Rated voltage: (external power supply): 3x400 Veff 50 Hz
      Rated voltage: (reduced operation): 3x345 Veff 47 Hz

      Voltage: 3x230 Veff

    • Cooling: AN / AF

    • Protection rating: IP00

    • Insulation class: F/H

    • Test voltage: EN 50124 / EN 60310

    • Operating temperature:  -40°C ... +55°C (optional +75°C)

    • Humidity: max. 95%

    • Pollution: PD 3

    • Vibration resistance: Cat.1 class A/B acc. to EN61373

    • Voltages: 24 / 42 / 110 / 230 / 400 / 690 Volt (Optional)

    • Switching group: Optional


    Customer-specific components

    Onboard power supply transformer can be custom designed. Are you interested in this product? Please contact us!

    Besides the standard components for use in the converter, REO offers customerspecific products - as individual components or as a complete solution in a ontainer. The most important criteria in railway engineering are availability for operation and passenger safety. Here, REO offers customized solutions that we develop step by step in close cooperation with our client. 

  • REOHM series NTT R D 158

    Max. continous power: 2600 W

    BW 156
    • Resistance values: 0,1 - 1 Ohm
    • Continuous power: 100 - 1210 W
    • max. operating voltage: 4200 V

    The resistor NTT RD 158 is a water-cooled damping resistor, which is used for traction in railway applications. The resistor is used in series with filter capacitors in the 1.5 kV and 3 kV DC network. 

    For this purpose, the device must be designed for a high single pulse energy and nominal voltage. The inductance of the resistor contributes to limit the inrush current - here are wirewound resistors the right choice.

    The advantage of the resistance unit NTT R D158 is that 4 damping resistors are housed in one unit. This means a compact construction and low cost when connecting the resistor.

    REO high-voltage resistors are designed, produced and certified specifically for the railway technology. The specially designed winding technology allows a higher withstand voltage due to the spatial separation of the wires. The use of railway-compatible, high quality materials, together with the complete encapsulation in profile design lead to protection classes up to IP 65.

    Maximum energy with minimum space

    • Continuous output: 2600 W

    • Max. operating voltage: 4200V

    • Resistance value: 0,1 - 1Ohm

    • Average pulse load: 1x per hour 20kWs - within 100ms

    • Maximum pulse load: 20x per year 120kWs -within 20ms

    • Protection class: IP00-IP65

    • Other ratings upon request

  • Series WKO-2C-B

    Double core technology closed-loop current transformers for railway engineering

    Series WKO-2C-B
    • Primary rated current: 500 - 2000 A
    • Measurement range: 0...3000 A
    • Frequency range: 120000 Hz

    The current transducer WKO-2C-B with hall effect elements and double-core  technology has an extended frequency response up to 150 kHz and an accurate phase response. The WKO-2C-B guarantees an increased current measurement accuracy better than 0.3% in the whole frequency range: DC to 150 kHz.

    A completely redesigned electronics ensures that the new C/L current transducer has better drift compensation and an extended temperature range from -40°C to 85°C.

    Modular design

    The current transformer has a modular design which allows a variety of mounting options. The cost-effective basic model consists of a housing with screw terminals, bushing for cable and holes for fixing. Optionally, the transducers are available with mounting kit for busbars, molex connectors and feets for horizontal or vertical mounting.

    According to: 

    • EN 50178:1997

    • UL 94-V0

    • EN 50178            

    • EN 50155:2007

    • IEC 61373:2010

    Typical applications

    • Railway engineering

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