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Combined current/voltage transformer TG COMBI

Gas-insulated instrument transformer for enhanced safety and reliability

TG COMBI gas-insulated combined current and voltage transformer is built for revenue metering and protection in high voltage networks. The TG COMBI has been designed for voltage up to 420 kV.


  • Revenue metering 
  • Protective relaying
  • System control and indication of power flow

Why Hitachi Energy?

For the TG COMBI the combination of SF6 gas insulation and with a composite insulator, offers several advantages:

  • Explosion proof design
  • Absence of partial discharge
  • Dielectric mean not subjected to aging
  • Higher performance in very heavy polluted environments
  • Maintenance free

The integration of two purposes (current transformer and voltage transformer) in one piece of equipment provides benefits in terms of:

  • Cost of the equipment
  • Quantity of gas
  • Space required
  • Costs of transportation and packaging
  • Time for erection and commissioning
  • Cables for interconnection
  • Foundations and structures

Brief performance data

Installation Outdoor
Design Top-core Type
Insulation SF6 Gas
Highest voltage for equipment 72.5 - 420 kV
Power frequency withstand voltage Up to 630 kV
Lightning impulse withstand voltage Up to 1.425 kV
Short-circuit current Up to 63 kA
Insulators Composite
Ambient temperature -50°C to +40°C
Creepage distance ≥ 25 mm/kV
Accuracy Meets all IEC and IEEE metering and protection classes
  other values on request
power plant engineer for substation

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