Siemens has received orders from US-based energy provider Pacific Gas and Electric (PG&E) for SF6-free dead-tank circuit breakers and gas-insulated switchgear (GIS), which will be used for California’s 115kV high-voltage grid.
Image: The 8VN1 blue GIS gas-insulated switchgear (GIS). Photo courtesy of Siemens AG.
The orders comprise dead-tank circuit-breakers for 72.5kV and 115kV as well as GIS for 115kV.
The circuit breakers use vacuum interrupters for switching functions and treated air (clean air) as the insulating medium, and eliminate the use of sulfur hexafluoride (SF6). The first delivery will be in mid-2019.
In July 2018, PG& E launched an initiative to cut greenhouse gas (GHG) emissions from its operations by one million tons, and the use of highly sustainable electric switchgear is one of the means to achieve this.
PG& E substation and T-line standards engineering manager Tom Rak said: “We are very pleased with the development of more and more SF6 free solutions for high voltage applications. They support PG&E at meeting the challenge of climate change while providing affordable energy to its customers.”
Siemens energy management division CEO Ralf Christian said: “In recent years, Siemens has been hard at work developing a new generation of high-voltage products that offer outstanding performance and sustainability.
“Our goal is to offer SF6-free high-voltage products preferably on all voltage levels in power transmission. They can already be used in many sectors.”
The company’s 3AV1 DT dead-tank circuit breakers offer a rated voltage of 115kV, a rated short-circuit breaking current of up to 40kA, and a rated current of up to 3,000A.
The 8VN1 GIS features a rated voltage of 115kV, rated short-circuit breaking current of 50kA, and a rated current of 3,000A. SF6-free circuit-breakers and GIS, a development of insulation using SF6, use a vacuum interrupter unit that handles the switching and arc-extinguishing functions.
Purified air in a ratio of 80% nitrogen to 20% oxygen (clean air) provides the insulation for the current-carrying conductors inside the housing.
The technology has been developed by Siemens to meet climate neutrality requirements by combining vacuum interruption systems for switching and for arc extinguishing with clean air as the high-voltage insulating medium.
The benefits of SF6-free switching technology include high switching power with the same footprint for outdoor and dead-tank circuit breakers.