As high-density data centers and artificial intelligence (AI) applications proliferate, electrical infrastructures must evolve to meet rising demands for availability, resilience, and energy efficiency. Legrand addresses these needs with Keor FLEX, a modular and redundant uninterruptible power supply (UPS) solution designed to ensure maximum service continuity, simplify maintenance, and adapt to the dynamic environments of modern data centers.
 

Maximum Availability Through Modular Redundancy

Keor FLEX features a fully modular architecture that distributes intelligence, power, conversion, and redundancy across every critical subsystem. This design eliminates any single point of failure and ensures a continuous power supply even in the event of component faults or during active maintenance.  

Redundancy is embedded at multiple levels:

• Power Modules: These operate in parallel and are true hot-swap modularity with hot synchronization, each with independent control and protection circuitry. If one module fails, the remaining modules instantly compensate for the loss, maintaining output performance.  
• Dual Communication Buses: Two independent communication pathways maintain real-time synchronization between modules and supervisory logic. This duplication eliminates the risk that a single communication fault could disrupt coordination or power conversion.  
• Duplicated Auxiliary Subsystems: Low-voltage power supplies and internal monitoring circuits ensure no supporting component becomes a vulnerability.
• Automatic Static Bypass: This is equipped with its own dedicated Digital Control Unit (DCU) that operates independently from the main UPS controller, ensuring a continuous power supply even in the event of a major main system failure.

The architecture’s robustness, both physical and functional, has been verified using the Failure Modes, Effects and Criticality Analysis (FMECA) method, confirming that the modular and redundant design fully meets reliability requirements.  
 

Hot Maintenance to Minimize Downtime

Keor FLEX supports true hot maintenance, allowing for module replacement without service interruption. This capability is based on a secure physical and functional design inspired by Legrand's plug-in power systems and follows strict procedures to avoid arcing and ensure technician safety. Technicians have direct, secure access to power connectors, facilitating uninterrupted thermographic controls. In the event of a module failure, it can be replaced without disrupting the supply of critical loads, thanks to the hot-swappable power module architecture. 
 

Management of Dynamic Loads and Power Peaks

AI and High-Performance Computing (HPC) servers produce rapid load variations with power peaks that can double or triple consumption in milliseconds. These fluctuations impose significant thermal and electrical stress on the components. Keor FLEX addresses this challenge by using silicon carbide (SiC) semiconductors that offer up to 98.5% efficiency. This reduces losses and operating temperatures, extending the life of the chips (up to 175°C, compared to 125°C for conventional IGBTs). Furthermore, high-frequency digital regulation enables instantaneous responses to current variations, maintaining a stable voltage even during recurring peaks.

When consumption spikes occur, Keor FLEX can instantly limit peak power and provide additional energy from its internal battery, easing the load on the network or generator. Once the peak has passed, the battery recharges automatically, operating according to micro-cycles of charging and discharging. This process stabilizes the voltage and frequency while preserving the quality of the power supply.

Scalable Architecture for Growing Rack Densities

As power density per rack escalates, Keor FLEX delivers modularity that allows for both power scalability and large-scale paralleling.  

• Internal Modularity: Scale the system capacity up to 1,200 kW by adding 100kW power modules.
• System Paralleling: Pair up to four units in parallel for a total power of 4.8 MW per UPS system, ideal for AI supercomputing and hyperscale environments.
• Modularity and Compactness: At 1.2 MW, the Keor FLEX cabinet balances a compact footprint with the clearances and conductor sizes needed to safely handle high currents, while ensuring high efficiency and easy maintenance access.

Cybersecurity: Protecting Critical Systems

Unauthorized access to or control of a UPS system can lead to power disruptions, data loss, and system failures, causing significant financial and reputational damage. Research published by the Department for Science, Innovation and Technology (DSIT) estimates that the annual cost of significant cyberattacks in the UK is £14.7 billion, equivalent to 0.5% of the UK’s GDP. Cybersecurity is key to Keor FLEX’s design, protecting the control and communication systems of AI data centers, where increased connectivity and network complexity heighten potential vulnerabilities.

Physical Access Measures:

• The systems are installed in secure technical rooms that are accessible only to authorized personnel.  
• Actuators are protected by mechanical keys.
• The control panel is locked with a password.  

External & Unauthorized Access Measures:

• The design allows for remote supervision via fieldbuses over an isolated local area network (LAN).
• No remote-control commands are accepted; all piloting actions must be carried out locally after authentication by the operator.  
• Access to the USB maintenance port, which is reserved for authorized technicians, is subject to a limited-time certificate of authenticity.  
• Data or file exchanges are fully encrypted, and decryption is possible only after validation of the certificate, preventing unauthorized transfers.  
• The communication computer, responsible for managing buses and USB interfaces, is physically and functionally independent of the UPS core. Even if the internal network is compromised, only the communication module would be affected. Essential power functions and local control remain fully operational, ensuring service continuity and system resilience against cyber threats.

The Keor FLEX UPS meets the demands of high-density data centers, offering scalable power, maximum service continuity, and maintenance without downtime, designed to adapt as requirements evolve.

Explore the full Keor FLEX architecture and see how it delivers continuous protection for AI-ready data centers here.