Railway transformer NTT 400 U

On-board transformer for underfloor installation


Laden Sie sich unseren umfangreichen Katalog herunter und entdecken Sie auch viele weitere Produkte von REO.

Railway transformer NTT 400 U

On-board transformer for underfloor installation


The REO transformer NTT 400 U is designed for on-board power supplies, which are fed by the auxiliary converter.The transformer NTT 400 U is the complete, ready to use-unit with transformer and housing.  It 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. 10 – 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
  • Insulation class: F/H
  • Test voltage:  EN 50124 / EN 60310
  • Operating temperature:    -40°C … +55°C (optional +75°C)
  • Humidity: max. 95%
  • Pollution:  PD 4
  • 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 customer specific products – as individual components or as a complete solution in a container.  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
  • Natural Cooling
  • Pollution degree PD4
  • Various performance classes

Technical specifications

  • Rated power : 10000 – 30000 VA
  • Input voltage : 3×440 V

Dimensions in mm

The REO transformer NTT 400 is...

The REO transformer NTT 400 D...