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Eco-efficient gas-insulated switchgear with new gas mixture as alternative to SF6

Technology for high-voltage and medium-voltage applications

Hitachi Energy is committed to developing eco-efficient products which reduce use of resources and the effects on the environment throughout their lifecycle. The main insulation gas used in high and medium voltage switchgear is SF6 gas which has several important features. However, SF6 is a known greenhouse gas and while leakage rates are very low its lifecycle management requires careful handling for utility and industrial users and comes with some associated costs, particularly when decommissioning aging substations.

The fluoroketone-based SF6 alternative gas mixture is a chemical compound developed for switchgear applications by Hitachi Energy in collaboration with 3M. It has a dielectric performance similar to SF6 when utilized in indoor applications, but with very low Global Warming Potential (GWP)*. The new gas mixture also has an adequate current interruption performance but in this respect SF6 is superior. Therefore it will be first deployed for applications with a nominal voltage up to 170 kV where typically short circuit currents are below 50 kA. The gas mixture is non-toxic and non-flammable.


Installations to be currently undertaken where lower environmental footprint is a criterion and for applications with a nominal voltage up to 170 kV where typically short circuit currents are below 50 kA.

Why Hitachi Energy?

  • Hitachi Energy is the pioneer in GIS technology with 50 years of proven experience
  • Worldwide footprint and service network
  • World leader through continuous research and development (R&D)
  • GWP of new gas mixture is almost 100 percent lower than GWP of SF6
  • Regulatory procedures for SF6 such as maintaining inventory, special requirements in gas handling, filling and decommissioning of the equipment will be avoided
  • Savings can be made in SF6 related taxes which are applicable in some countries
  • The new gas mixture is the only one available so far that has been type tested according to IEC standards which meets performance criteria and has a GWP ≤1
  • Significant lowering of carbon emissions over the equipment life cycle. For example with the deployment of high-voltage GIS with the eco-efficient gas mixture, carbon dioxide (CO2) equivalent emissions can be lowered by up to 50 percent through the lifecycle of the equipment. (The CO2 emissions consist of approximately 50 percent from raw materials, manufacturing and thermal losses, and 50 percent from SF6 emissions based on a 30-year service life)

*GWP (Global Warming Potential): The global warming potential describes how much heat a greenhouse gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of carbon dioxide. GWP is expressed as a factor of carbon dioxide.

Brief performance data

Eco-efficient gas-insulated switchgear (GIS) ZX2 AirPlus ELK-14 AirPlus
Rated voltage [kV] 36 170
Rated frequency [Hz] 50 50
Rated short-duration power-frequency withstand voltage [kV] 70 325/375
Rated lightning impulse withstand voltage [kV] 170 750/860
Rated normal current – busbar and exit [A] 2000 1250
Rated short-time withstand current (up to 3 s) [kA] 31.5 40
Rated peak withstand current [kA] 80 100
Installation indoor indoor

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