Railway transformer NTT 400

Onboard power supply transformer


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Railway transformer NTT 400

Onboard power supply transformer


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.
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.


  • Vibration and shock tested according to DIN 61373 Cat 1 Class B
  • High efficiency
  • Low idling losses
  • Reduced field scattering
  • Low noise
  • Reduced weight
  • High mechanical resistance
  • Mounting in the exhaust duct of the power converter
  • Integration into an existing cooling system
  • Pollution degree PD3
  • Shield winding possible
  • Alternative switching groups
  • Temperature monitoring

Technical specifications

  • Power. 1 – 30 kVA
  • Rated voltage


  • Rated voltage: (Normal operation): 3×440 Veff 60 Hz
  • Rated voltage: (external power supply): 3×400 Veff 50 Hz
  • Rated voltage: (reduced operation): 3×345 Veff 47 Hz


  • Voltage: 3×230 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

Dimensions in mm