Powering gigawatt-scale data centers generally occurs at two voltage levels:
- Cables laid outside the buildings connect the data halls to the transmission or distribution network. They provide power to data centers from the primary and secondary HV substation using HV and/or MV cables.
- Within the buildings, the racks and IT devices in the data halls are connected via distribution cables at a low-voltage level.
Each voltage level brings its own challenges when it comes to meeting the enormous energy demands of data centers such as AI data centers.
At the medium-voltage level, the total performance of a data center is distributed across its various data halls in which the servers are hosted. To give an idea of the scale, a next-generation data center may need somewhere in between 100 MW and 400 MW per data halldepending on size and design selection. Providing such power requires a very large number of parallel cables. Since these cables are generally buried underground, this leads to several problems:
- a large physical footprint,
- very high civil engineering costs,
- and electrical losses (Joule losses), which reduce efficiency and heat the ground.
Example:
Providing a single 300 MW data hall requires 36 large cross-section cables (600 mm²) at 33kV. A 1.8 GW data center with six 300 MW data halls would therefore be required 216 underground cables– a huge, complex and extremely expensive infrastructure.
On the low-voltage level, near the data hall, a transformer converts the medium voltage down to low voltage in order to supply the IT devices directly. Delivery 100MW to 400MW at 480V or 600V leads to extremely high currents in the range of 6 to 10.
Such currents require a very large number of low-voltage cables to be laid within the data hall Bus routes. This solution comes with several limitations:
- a significant footprint (space occupancy),
- a complex and expensive cable installation architecture,
- strict requirements for electromagnetic compatibility, both between cables in the same busbar and with neighboring devices,
- and Thermal Management: Traditional copper cabling generates significant heat, resulting in increased demand for HVAC systems and contributing to operational inefficiencies.
Over and beyond Joule losses alone can reduce the overall efficiency of the data center 5 to 10%. Nowadays some solutions are even being considered Cooling of low voltage cables to limit these losses and improve efficiency. But that underlines that Limitations of traditional cabling solutions.