Vacuum interrupter unit for CO2-neutral 170kV/50kA switchgear

Inhalt:
One key enabling technology for realizing CO2-neutral switchgear for a voltage level of 145 kV and above is the vacuum interrupter technology. It has been successfully established in medium-voltage switchgear for decades. The introduction of a 145 kV climate-neutral gas-insulated switchgear as well as a climate-neutral 145 kV circuit breaker based on vacuum interrupter units and clean air as insulating medium reveals the application of the vacuum technology for future climateneutral switchgear. The next step in this development process addresses a vacuum interrupter unit for 170 kV CO2-neutral switchgear. Thus, in this contribution the world’s first single-breaking vacuum interrupter unit with 170 kV rated voltage and 50 kA rated short-circuit interruption current is presented. The dielectric performances of the vacuum interrupter unit and of the contact design are significantly improved as compared to existing 145 kV solutions. The realized conception of the contact system comprises the shape of the contact components, a significant reduction of the accelerated mass of the contact system, and a well-defined control of the contact travel curve of the driving mechanism enabling maximum shortcircuit switching performance. The inner and the outer dielectric design of the vacuum interrupter unit are optimized to achieve a more compact switching tube that meets the requirements of future climate-neutral gas insulated switchgear. For this purpose, the dielectric design of the vapor shields inside the vacuum tube and of the ceramic insulators is optimized. This leads to a significant reduction of the total ceramic length. A modular construction of the vacuum interrupter unit for 170 kV climate-neutral switchgear together with a high dielectric strength in a compact design yield a major building block for new high-voltage products, such as live-tank and dead-tank breakers or GIS for 170 kV/50 kA and above.