The first 123kV/40kA/3000A dead tank breaker development was a result of a partnership between a prominent manufacturer and a large West Coast utility starting in 2018. This successful partnership work passed an important milestone in the first half of 2021 with the completed type test according to IEEE/ANSI standards for the first 123kV/40kA/ 3000A dead tank design. The delivery of the first dead tank circuit breakers has been completed. The next steps include type tests for 145kV/40kA with the first deliveries planned for 2022. A third step the type test and first deliveries for 145kV/63kA are planned for 2023. GHG-Free Gas-Insulated Switchgear (GIS) up to 145 kV The 145kV/40kA/3150A GIS is type-tested according to IEC and IEEE (Figures 6 and 7). More than 350 bays are contracted and more than 25 are in operation. The next important milestone is the completion of the type test in late 2022 and the first delivery to a substation in California in late 2022. Several large utilities across the United States are introducing pilot sites with non-SF6 equipment, including clean air vacuum circuit breakers and GIS systems. F-gas free 72.5, 123 and 145 kV live and dead tank circuit breakers are either already in service or on order. The objectives of the pilot installations are to gain experience long before regulations take effect or to achieve CO2-neutral grids. Table 3 shows clean air products from Siemens Energy that are currently in the field or will be soon. Field Evaluations and Results Conclusions The clean air live tank breakers installed in European and Australian networks in 2010 are still in operation. In the figure 5. First dead tank breaker outline, 123kV/ 40kA with vacuum interrupting and clean air insulation technology. Source: Siemens Energy. 136 ieee power & energy magazine April 2022 Show Issue