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Their usefulness as protectors and power supplies for all types of loads is, by definition, versatile, and this dual capability is utilised by countless businesses, industries, organisations, homes and infrastructure facilities, each with requirements that are, of course, extremely diverse and dependent on factors such as load capacity and power distribution. Therefore, based on these requirements, the first decision to be made when purchasing a UPS is whether to choose a single-phase or three-phase model.

Adaptable protection and power supply

A single-phase UPS can be considered the entry point to this type of system. They have a single input, a single output, and a single sinusoidal voltage transmitted via a circuit consisting of two cables: a phase and the neutral. Their use is generally limited to low-power applications, typically below 10 kVA or at most 20 kVA, particularly in small domestic installations, offices, and shops.

Single-phase UPS systems typically use conventional Schuko-type sockets, and because they use a single cable, the risk of overheating limits their power output. The main advantages of this type of UPS system are its low cost and straightforward installation, which is often plug-and-play. By contrast, three-phase UPS systems require three separate conductors that provide sinusoidal waves to supply the loads continuously; this means they require at least four cables: one for each phase and one for the neutral. The output, however, can be either single-phase or three-phase. Three-phase UPS systems are used in larger installations with critical loads such as data centres, hospitals, industrial plants and office complexes, as well as to protect equipment containing motors, such as lifts, pumps, and fans. They are usually designed to handle loads in excess of 20 kVA and can even reach the megawatt range. In addition to offering greater capacity, they are more efficient at distributing the load across the phases, which means the cables can be thinner than those in a single-phase UPS. This, in turn, increases the stability and reliability of the power supply when the power output reaches significant levels.

Nevertheless, the needs of businesses and industries often change, and they can therefore require different power supply configurations. Of particular note in this regard are versatile UPS devices for small installations and low or medium power ratings (up to 20 kVA), such as the SLC TWIN PRO RT3 MULTI, which can cater for both types of installation and utilise external batteries to extend their runtime to cover, for example, a larger number of servers, or to provide a longer backup period.

The UPS system's maximum power capacity can be achieved by connecting several of these units in parallel, with the additional option of providing redundancy in the event of a failure or to ensure continuity whilst maintenance tasks are carried out. Lastly, the management of the most critical loads can be customised by segmenting them into two priority levels and configuring the UPS to take even more crucial measures, such as supplying critical equipment only after a certain period has elapsed following a mains power failure.