Siemens and Reinhausen turn up the voltage for hungry AI racks

Siemens and Reinhausen engineering firms are jointly developing a solid-state transformer (SST) to provide 800-volt direct current (DC) power to densely packed AI datacenter racks. The growing demand for more powerful AI hardware has led datacenter operators to seek alternative methods of power distribution. Nvidia and other major industry players favor 800 VDC distribution, and thus Siemens and Reinhausen are creating a modular SST capable of converting medium-voltage alternating current (AC) up to 36 kilovolts into a stable 800 VDC output for downstream use.

Siemens believes the SST will offer a compact, galvanically isolated alternative to traditional multistage AC-to-DC conversion methods, reducing intermediate steps and enabling more efficient delivery to high-density AI infrastructure. Reinhausen's managing director, Wilfried Breuer, emphasized that datacenters supporting AI workloads are among the most power-hungry in the industry, with sudden load spikes potentially harming servers, storage, and cooling systems, leading to performance issues and outages.

Reinhausen's company views solid-state transformers as critical for these large, high-power structures, offering higher efficiency, direct grid-to-rack DC conversion, and reduced footprint. Siemens' CEO for Electrification and Automation, Stephan May, highlighted the collaboration's potential to strengthen their leading position in datacenter electrification.

The Register previously reported that Nvidia considers 800 VDC power distribution essential for AI infrastructure, and plans to shift towards it to support racks drawing 1 megawatt or more. While this may seem ambitious given the current average rack density of 11 kilowatts, hyperscalers like Google are already planning for megawatt-scale racks.

Nvidia has also developed its own MGX-compatible 800 VDC power rack, set to launch in the second half of 2026. Siemens and Reinhausen aim to commercialize their datacenter SST, but the company did not disclose a specific timeline. Another German electrical firm, Infineon, is also supporting 800 VDC and preparing its silicon carbide (SiC) power semiconductors for use in datacenter infrastructure.