Summary
- Schneider Electric assessed rack-level and facility-level 800 VDC architectures using standards-based and transient modelling.
- Arc-flash exposure varied with capacitor placement, topology, fault location, and protection response.
- No industry-wide guidance currently addresses converter-fed 800 VDC data centre systems.
Schneider Electric has published an arc-flash study covering two 800 VDC data centre power architectures, as AI systems push rack loads towards 400kW and above.
The analysis examined a rack-level design using a sidecar power cabinet and a centralised facility-level architecture. Schneider Electric used standards-based calculations, transient simulation, and system-level modelling to assess fault behaviour.
It found that arc-flash exposure depends heavily on system architecture, capacitor placement, fault location, reverse-current blocking, and the speed of protection devices.
Under many of the modelled conditions, the company said incident energy could be kept broadly comparable with conventional AC distribution. The result does not mean that 800 VDC is intrinsically safe or that a single calculation applies to every installation.
Arc-flash studies are established practice in AC systems, but Schneider Electric said there is no industry-wide guidance specifically covering the hazards personnel may encounter in converter-fed 800 VDC data centre architectures.
Capacitors dominate the first milliseconds
High-voltage DC systems contain power-electronic converters and stored electrical energy. During a fault, capacitors can discharge rapidly, creating a strong initial current that changes over a very short period.
That transient behaviour affects the amount of incident energy reaching a worker and the time available for protection to interrupt the fault. A simplified model can overstate exposure if it assumes the initial current remains constant.
In Schneider Electric’s rack-level sidecar case, conservative assumptions produced incident energy below a referenced personal-protective-equipment threshold of 1.2 calories per square centimetre, even without additional protection devices.
The centralised architecture produced potentially higher incident energy under a conservative case without overcurrent protection. Faults positioned upstream or downstream of reverse-blocking diodes changed back-feed, peak current, and the final result.
The distinction makes architecture a safety decision as well as an efficiency and cost decision. Moving conversion equipment from the rack area to a central location changes cable lengths, stored energy, fault paths, isolation points, and maintenance access.
It also changes the working environment. Operators need accurate labels, approach boundaries, isolation procedures, personal protective equipment, and training suited to fast DC faults.
Protection design must follow the architecture
The move towards 800 VDC is intended to distribute large amounts of electricity efficiently to dense AI equipment. Higher voltage reduces current for a given amount of power, which can limit conductor size and electrical losses.
It does not remove fault energy. Protection coordination, switching behaviour, capacitor placement, and converter response determine how quickly a fault develops and clears.
Schneider Electric’s work indicates that existing analysis frameworks can be applied when engineers use time-dependent, architecture-specific models. Treating nominal voltage as the primary indicator of exposure is insufficient.
Digital twins and detailed power-system simulations could become part of the safety case for these facilities. They allow engineers to assess different fault positions, device settings, component failures, and operating modes before the system is energised.
The model must remain aligned with the physical installation. Changes to converters, capacitor banks, firmware, protection settings, or cable routes may alter fault behaviour and require the study to be updated.
Maintenance procedures are another unresolved area. High-density systems are being designed for availability and modular replacement, increasing pressure to exchange components without shutting down an entire power train.
Schneider Electric said it has separately tested live-swap capability for 800 VDC systems. Local rules, equipment design, and the final protection architecture will still determine whether such work can be performed safely.
The study comes from a supplier developing both 800 VDC equipment and the ETAP modelling tools used in the assessment. Independent testing, operational evidence, and eventual standards will be needed as deployments grow.
Its immediate contribution is to show that risk cannot be inferred from voltage alone. Arc-flash protection must be designed around the complete converter-fed system before equipment selection and layout are fixed.
