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This guide takes you step by step through the assessment and selection of a scalable UPS. From the fundamentals of topology to advanced redundancy and efficiency criteria, you will find the information you need to make a technically sound decision. With more than six decades of experience in power electronics, Salicru backs every recommendation with proven, real-world expertise.

Key points: scalable UPS systems for critical infrastructure

• A scalable UPS allows you to increase electrical protection capacity as your installation’s needs grow, optimising the initial investment.
• Online double-conversion topology is the benchmark for critical loads because it eliminates transfer time in the event of a mains failure.
• A modular architecture with hot-swap modules reduces mean time to repair and improves system availability.
• Salicru offers modular solutions such as the SLC ADAPT series, designed to grow alongside data centres and public buildings.
• A preventive maintenance and remote monitoring programme extends the UPS’s service life and ensures long-term reliability.

What is a UPS and why is it critical to your infrastructure?

An uninterruptible power supply (UPS) is a device that provides immediate backup power when the mains supply fails or is affected by disturbances. Its role goes beyond providing a temporary backup: it filters the power, corrects voltage fluctuations and protects your equipment from spikes, harmonics and micro-outages.

In critical infrastructure such as hospitals, data centres, airports and telecommunications networks, a power cut can bring operations to a standstill, compromise sensitive data and generate significant costs. The UPS acts as a barrier between the mains and your loads, ensuring that the power supply is clean, stable and uninterrupted.

For this reason, choosing the right UPS is no minor decision. It requires a technical assessment that takes into account the power requirements of your loads, their criticality and your installation’s growth plans.

UPS topologies: which one best protects your critical loads?

Before choosing a scalable UPS, it is worth understanding the three main topologies, as they determine the level of protection your equipment will receive.

Offline or standby UPS

This is the most basic topology. The load receives power directly from the mains, and the UPS only intervenes when it detects a power cut. Although brief, the transfer time can affect sensitive equipment. It is recommended for non-critical loads such as workstations or home equipment.

Line-interactive UPS

It includes an automatic voltage regulator (AVR) that corrects voltage fluctuations without using the battery. It offers better protection than an offline model and is suitable for small servers, network equipment and offices with moderately sensitive loads.

Online double-conversion UPS

This is the benchmark topology for critical infrastructure. Power continuously passes through the rectifier and inverter, so the load receives fully regenerated, stable voltage. Transfer time is zero, eliminating any risk of interruption. For data centres, public buildings and demanding industrial environments, online double-conversion topology is the only option that provides total protection against mains disturbances.

What does it mean for a UPS to be scalable?

A scalable UPS is one whose power capacity can be expanded progressively by adding modules to the existing system, without replacing the entire unit. This approach is known as “pay as you grow” and has a direct impact on investment and day-to-day operations.

With a scalable UPS, you can size your electrical protection to match your actual load today and add capacity as your infrastructure grows. This avoids initial oversizing, reduces capital expenditure (CAPEX) and improves total cost of ownership (TCO).

Scalability also allows you to configure N+X redundancy. If one module fails, the remaining modules take over the load without interruption. This arrangement increases system availability and reduces the risk of a total shutdown.

Technical criteria for selecting a scalable UPS

Choosing a scalable UPS requires a methodical assessment. The following are the key criteria to consider before making a decision.

How do you calculate the power required for your UPS?

The first step is to list all connected loads: servers, network equipment, air-conditioning systems and access controls. For each device, record the rated power in VA or W, the starting current and the power factor. A sound design allows for a margin of between 20% and 30% above the calculated total load. This margin accommodates demand peaks and allows for growth without overloading the system from day one.

Autonomy and battery strategy

Autonomy determines how many minutes the UPS can power your loads using the energy stored in its batteries. For most critical applications, 5 to 15 minutes is enough to perform an orderly shutdown or allow a generator to start. VRLA batteries remain the dominant technology. Lithium-ion batteries are gaining ground thanks to their longer service life, lower weight and greater tolerance of higher temperatures. Assess the cost over the full life cycle, not just the purchase price.

What level of redundancy do you need?

Redundancy determines the system’s ability to keep operating if a component fails. The most common arrangements are N+1 (one additional standby module) and 2N (full system duplication). For high-availability data centres, an N+1 configuration with hot-swap modules offers a balance between protection and investment efficiency. If your installation requires availability close to 99.999%, consider a 2N architecture with an independent maintenance bypass.

Energy efficiency and operating mode

UPS efficiency has a direct impact on your operating costs and your installation’s carbon footprint. A high-end online double-conversion UPS can achieve efficiency above 96% in VFI mode. Some units include eco or smart-efficiency modes that raise efficiency above 98% when mains conditions are stable. Through its Code of Conduct for Data Centres, the European Commission classifies UPS systems into two efficiency levels: Standard and Elite. Choosing equipment that meets the Elite level contributes to the goal of energy neutrality and reduces electricity consumption over the system’s service life.

Modular architecture: the key to scalability

Modular architecture is at the heart of a scalable UPS. Instead of using a single, monolithic power block, the system consists of independent modules installed in a common frame. Each module operates as a self-contained unit and shares the load with the others.

Advantages of hot-swap modules

Hot-swap modules can be added, removed or replaced without shutting down the system. This capability significantly reduces mean time to repair (MTTR) and simplifies maintenance. When a module needs to be inspected, it can be removed and replaced in minutes without affecting the protected loads. Modularity also improves the system’s overall mean time between failures (MTBF), as each module has its own control and protection. A module failure is isolated without compromising the others.

How can you integrate Salicru’s SLC ADAPT series into your infrastructure?

Salicru’s SLC ADAPT series is an example of a modular approach designed for critical environments. Configurations from 25 kVA to 1,500 kVA, with 25 and 50 kVA hot-swap modules, allow you to size the system to the current load and expand it progressively. Online double-conversion technology with three-level IGBT DSP control ensures a precise response to load fluctuations. The option to configure up to three systems in redundant parallel operation further increases availability for the most demanding applications.

Scalable UPS applications in critical environments

Every environment has specific requirements. Here is how a scalable UPS can adapt to the main critical infrastructure scenarios.

Scalable UPS for data centres

Data centres require the highest levels of availability. A modular UPS allows you to start with the right power capacity for the initial IT load and scale up as racks fill and new servers are installed. The implementation of a UPS in a data centre should include at least N+1 redundancy, centralised monitoring and a maintenance bypass for interventions without interruption. Artificial intelligence and high-performance computing workloads add another factor: fluctuating load profiles that place unconventional demands on the UPS. A UPS designed for these conditions must withstand rapid changes in demand without any loss of performance.

Scalable UPS for public buildings

Hospitals, airports, railway stations and administrative centres depend on a continuous power supply to maintain safety and essential services. In these environments, safety regulations often require backup systems with sufficient autonomy for an orderly evacuation or transfer to emergency generators. A scalable UPS makes it easier to adapt to extensions of a public building, where electrical demand may grow as new rooms, medical equipment or security systems are added.

Scalable UPS for industrial environments

In manufacturing plants and automation environments, electrical disturbances can cause production stoppages, PLC failures and loss of control data. A high-power three-phase UPS such as Salicru’s SLC X-TRA series protects production lines, SCADA systems and automation equipment with the robustness required in industrial environments. Parallel operation and compatibility with generators make these solutions a key part of any plant’s operational continuity strategy.

Monitoring and preventive maintenance for a scalable UPS

Installing a scalable UPS is only the first step. To ensure that it performs its function when you need it most, a programme of condition-based maintenance and continuous monitoring is essential.

What should a preventive UPS maintenance plan include?

An effective preventive maintenance plan includes battery condition inspections, checks of electronic modules, internal technical cleaning and backup tests under load. Best practice recommends at least two visits a year for critical installations. It is also advisable to record every intervention and analyse data trends to anticipate component degradation before it develops into a fault. Salicru offers maintenance and remote monitoring contracts that apply predictive maintenance principles through real-time data analysis.

Remote monitoring and artificial intelligence for UPS systems

Modern systems allow you to monitor a UPS in real time from any location. Parameters such as voltage, charge current, battery temperature and module status are sent to management platforms that generate early warnings. Applying artificial intelligence to the analysis of this data makes it possible to detect abnormal patterns and predict failures before they occur. This predictive approach reduces the risk of downtime and optimises the planning of spare parts and technical resources.

UPS batteries: technologies, service life and best practices

Batteries are the most sensitive component of a UPS. Their condition determines the system’s actual autonomy during a mains failure, so they require specific attention.

VRLA or lithium-ion: which technology is best?

VRLA batteries (valve-regulated lead-acid) are the traditional option. They have a lower purchase cost and use a well-established technology. Their typical service life ranges from 3 to 5 years, depending on temperature conditions and the charging regime. Lithium-ion batteries offer a significantly longer service life, higher energy density and greater tolerance of high temperatures. Although their initial price is higher, their total cost of ownership may be lower because several replacement cycles can be avoided.

How can you extend the service life of your UPS batteries?

Ambient temperature is the factor that has the greatest influence on battery longevity. Keeping the environment below 25°C can double battery service life compared with an ambient temperature of 35°C. Avoid loading the UPS above 80% of its rated capacity. Schedule regular autonomy tests to check the actual condition of the battery bank. An intelligent charging system, such as the Batt-Watch incorporated into Salicru equipment, adjusts charging parameters to minimise stress on the cells and extend their service life.

Sustainability and energy efficiency in electrical protection

Electrical protection cannot be separated from sustainability. Data centres and critical infrastructure consume significant amounts of energy, and the UPS is a key link in the efficiency chain. Choosing a UPS with Elite-level performance under the European Commission’s Code of Conduct not only reduces direct electricity consumption, but also lowers the thermal load on air-conditioning systems. Lower energy losses in the UPS mean less heat dissipation and, therefore, lower cooling costs. Salicru aligns its entire UPS range with the most demanding efficiency standards and maintains an active commitment to sustainability as a pillar of its mission: to ensure a continuous, economical and environmentally friendly power supply.

Step-by-step guide to assessing and choosing your scalable UPS

If you are selecting a scalable UPS for your infrastructure, follow these steps to make an informed decision.

Step 1: audit your loads and define their criticality

Classify each device according to its level of criticality: essential (cannot tolerate any interruption), important (can tolerate brief interruptions) or auxiliary (can operate without a UPS). Focus UPS protection on essential and important loads, and size the system according to their combined power.

Step 2: determine autonomy and your generator strategy

Define how many minutes of autonomy you need according to your emergency protocol. If you have a generator, 5 to 10 minutes is usually enough for the transfer. Without a generator, consider greater autonomy or implement an orderly shutdown system.

Step 3: choose the topology and redundancy arrangement

For critical loads, choose online double-conversion topology. Define the redundancy arrangement (N+1 or 2N) according to the required availability level and available budget.

Step 4: assess the modular architecture and capacity for growth

Check that the UPS allows you to add modules without interrupting service. Verify the frame’s maximum power capacity and the number of modules it can accommodate. Make sure the solution covers your projected growth over the next 5 or 10 years.

Step 5: analyse the total cost of ownership (TCO)

TCO includes the purchase price, electricity consumption, battery costs, maintenance contracts and the space occupied by the equipment. A high-efficiency modular UPS will generally offer a lower TCO than an equivalent monolithic unit.

Step 6: check compatibility and monitoring options

Confirm that the UPS has interfaces (SNMP, RS-485, relays) compatible with your building management system (BMS) or DCIM platform. Integration makes day-to-day operation easier and speeds up responses to incidents.

In conclusion: how to ensure power continuity in your critical infrastructure

Selecting a scalable UPS for critical infrastructure is not a decision to take lightly. It requires an understanding of your loads, anticipating growth, assessing topologies and designing a redundancy arrangement that balances protection and investment. Modular architecture with hot-swap modules is now the most flexible and efficient solution for data centres, public buildings and industrial environments. It combines scalability with high availability and reduces operating costs over the system’s life cycle.

With more than 60 years of experience in power electronics, Salicru supports you at every stage of the process, from initial sizing to predictive maintenance, with electrical protection solutions designed to grow with you. Download our technical resources or contact our team to take the first step towards electrical protection tailored to your needs.

Frequently asked questions about UPS systems for critical infrastructure

What is the difference between a modular UPS and a monolithic one?

A modular UPS allows power modules to be added or removed independently, adapting capacity to the actual load. A monolithic UPS has a fixed power capacity that cannot be increased without replacing the entire unit. Salicru’s SLC ADAPT series can be scaled from 25 kVA to 1,500 kVA using hot-swap modules.

How much autonomy does a data centre UPS need?

The required autonomy depends on your emergency protocol. With a generator, 5 to 15 minutes is enough to cover the transfer. Without an auxiliary generator, you will need higher-capacity batteries or an orderly shutdown system to protect your data.

What does N+1 redundancy mean in a UPS system?

N+1 redundancy means that the system has one more module than the minimum required to supply the load. If one module fails, the standby module automatically takes over its share of the load, ensuring continuity of supply without manual intervention.

How often should I carry out preventive maintenance on my UPS?

Best practice recommends at least two preventive inspections a year for UPS systems in critical environments. Salicru offers preventive and predictive maintenance contracts that include remote monitoring, load tests and trend analysis to anticipate failures.

How does temperature affect UPS battery performance?

Temperature has the greatest impact on battery service life. Every 10°C above the recommended 25°C can approximately halve the service life of VRLA batteries. Maintaining suitable environmental control is just as important as maintaining the equipment itself.