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Gas-insulated Station service voltage transformer (72.5 – 550 kV)

All transformation ratings in one single equipment

A Station service voltage transformer combines the characteristics of a voltage transformer with the capability of a distribution transformer, having an output sufficient for smaller auxiliary loads. Hitachi Energy's gas insulated station service voltage transformers are designed for primary voltage systems up to 550 kV, and have following features:

  • Laminated steel core with oriented grain, having a high level of permeability
  • Electrolytic copper windings
  • Composite insulation
  • Aluminum alloy enclosure
  • Suitable for outdoor installation
  • Remote monitoring of the internal insulation level through pressure gauge having an alarm threshold and lock threshold
  • A pressure relief device to protect the apparatus from internal overpressure


  • Additional metering windings
  • Off load tap changer
  • Windings temperature sensor


  • Power source for auxiliaries in sub-station
  • Rural/remote area electrification
  • Oil and gas field power
  • Railroad/Airports electrification
  • Mining and construction power
  • Hospital and defense installations
  • Switching and substation control
  • Wind and solar power generation
  • Flood control and pumping stations
  • Lighting of transmission lines for aviation safety
  • Remote cell phone towers

Why Hitachi Energy?

  • Cost-effective solution for isolated applications
  • Perfectly suited for integration with a complete high voltage switchgear bay
  • Auxiliary power supply directly from high voltage line
  • HV to LV and HV to MV direct transformation
  • High safety thanks to SF6 insulation and polymeric bushings: explosion-proof, not flammable
  • Maintenance-free

Brief performance data

Parameter TIP UG
Installation Outdoor
Insulation SF6 gas or SF6 / N2 mixture
Highest voltage for equipment 72.5 – 550 kV
Power frequency withstand voltage Up to 630 kV
Lightning impulse withstand voltage Up to 1.550 kV
Max. output per phase Up to 500 kVA Up to 167 kVA
Secondary voltage Low or Medium Voltage Low voltage
Insulators Composite
Minimum ambient temperature

-30 ºC (100% SF6)

-50 ºC (SF6 / N2 mixture)

Maximum ambient temperature 50°C
Pollution Level IV (Very Heavy)
Accuracy Meets all IEC and IEEE metering and protection classes

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