Manufacturer: Hitachi Energy
Original publication date: 12 June 2026
Topic: SF₆-free 420 kV gas-insulated switchgear commissioning
Hitachi Energy and TenneT Germany have completed final high-voltage site acceptance tests for an SF₆-free 420 kV gas-insulated switchgear installation at the Erzhausen substation near Hanover.
Project milestone
The companies first announced the project in 2022. The latest step moves the installation from factory development and validation into commissioning in a real transmission substation. Hitachi Energy describes it as the first installation of SF₆-free GIS at the 420 kV level validated in an operating substation environment.
The equipment belongs to Hitachi Energy’s EconiQ portfolio. The manufacturer states that the design eliminates SF₆ while maintaining the footprint and performance expected from conventional high-voltage GIS.
What the site test demonstrates
- High-voltage testing was completed on the installed assembly, not only on a factory prototype.
- The application addresses the 420 kV level used in the backbone of the European transmission network.
- The milestone provides an operational reference for utilities evaluating alternatives to SF₆.
Why it matters
Type-test evidence and product ratings remain fundamental, but transmission operators also need confidence in transport, assembly, interface control, site testing and long-term service. Successful on-site validation reduces one important implementation risk. It does not mean every 420 kV project is interchangeable: bus configuration, cable or bushing interfaces, environmental conditions, protection integration and maintenance strategy still require project-specific engineering.
Source note: This is an independent editorial summary prepared by Learn Switchgear. Technical claims and “world first” wording are attributed to Hitachi Energy and TenneT. Read the original Hitachi Energy press release.