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Medium Voltage Power Distribution in Data Centres

The increasing power demand of the Data Centres, particularly in the colocation sector, has brought new challenges and paradigm shifts in the electrical design of the installations. It has become necessary to implement medium voltage internal distribution grids to address both efficiency and cost considerations.

This fact arises new questions such as what the most suitable voltage level is to meet sustainability and efficiency requirements.

Impact of Voltage Level on Internal Distribution

IT design power is a function of the product of line voltage on the site and the current demanded from the grid. Increasing the voltage level reduces the current through the conductors. Conversely, a decrease in voltage level results in higher currents through the conductors. The size of the cables and equipment is directly determined by the resulting current, which in turn impacts installation costs. But can this impact be estimated in advance?

Let´s assume in a simplified scenario a data centre with an installed power of 15 MW, a power factor of 1, and a single incoming feeder. At a network voltage of 11 kV, the current would have a value of 787 A. If we repeat this calculation for a 24kV network voltage, the current drops to about 360 A.

The increase in network voltage reduces the current through the feeder to approximately 45% of what it would be at the same power level in a lower voltage level. Assuming linear and constant loads, we can extrapolate this result to multiple feeders and loads.

Additionally, from the perspective of conductor losses, we know that these depend on the material from which they are made and are proportional to the squared current flowing through them. This means that losses increase exponentially with linear increases in current.

By performing a similar calculation to the previous one, we can determine that conductor losses can be reduced by up to 80% simply by raising the voltage level from 11 kV to 24 kV.

From a cost perspective, increasing the voltage level not only helps avoid losses and improve efficiency (OPEX) but also reduces the size of the conductors, leading to savings in the construction phase (CAPEX).

GWP Index of Medium Voltage Switchgear

Before the EU Regulation 2024/573 came into effect, SF6-insulated GIS solutions were the best option when selecting medium-voltage switchgear, typically at 24 kV and 36 kV voltage levels. SF6-insulated switchgear ensures safe operation with compact dimensions compared to hybrid switchgear (vacuum switching and air insulation), but it comes with the significant drawback of the high GWP (Global Warming Potential) of SF6 gas. Although this type of equipment seals the gas inside the tank, precautions are needed when handling the equipment since a leak will have a significant impact as a greenhouse gas, with an impact about 23,500 times greater than CO2 equivalent. Furthermore, proper processing of these assets at the end of their life cycle is necessary.

These factors have been strongly decisive in selecting switchgear up to now, favouring air insulated switchgear and as a consequence influencing the choice of voltage level.

The implementation of the aforementioned regulation, which limits de use of dielectric gases based on the GWP level of the different solutions has not posed a threat but rather a great opportunity for the sector, primarily due to the technological shift it represents. The implementation of the EU Regulation will define new boundaries for the 24kV product range from 2026 onwards. switchgear manufacturers are now presenting SF6-free solutions that match the performance of traditional SF6 GIS switchgear.

This innovation allows us to reap the benefits of a higher voltage level, such as 24 kV, while combining the advantages of GIS switchgear without the drawbacks SF6 technology.

At Ormazabal, we have developed solutions using natural industrial air and without fluorinated gases, ensuring high performance, reliability, and safety. This allows operators to implement our solutions with “zero uncertainties” regarding environmental, health, or safety concerns, while complying with European fluorinated gas regulations and climate neutrality goals.

With these innovations, we bring to the market products that enable the sustainable transition of electrical network, facilitating the integration of renewable energy and the electrification of society, reinforcing our commitment to leading the transformation of networks toward an SF6-free future.

Conclusions

The increasing power demand from Data Centres and the need to prioritize sustainability suggest the necessity of raising the voltage level in substations to around 24 kV.

Increasing the voltage level from 11 kV to 24 kV can result in up to an 80% reduction in losses.

Until now, high voltage levels required SF6-insulated GIS switchgear, as air-insulated (vacuum switching) switchgear was bulky, complex to maintain, and posed operational risks.

Raising the voltage level also allows for optimizing conductor size, leading to cost savings.

From 2026, Ormazabal will be delivering its SF6 free product, up to 24kV for both secondary and primary distribution, with a GWP<1 to the market combining the best of both worlds: reducing losses by raising the voltage level without the disadvantages of SF6 insulated switchgear.