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Its usefulness as both a protector and electrical supplier for all types of loads is versatile by definition. This dual functionality is used by countless companies, industries, organisations, homes and infrastructures, although their needs are, of course, highly diverse, depending on factors such as load capacity and energy distribution. Based on these requirements, one of the first decisions when purchasing a UPS is whether it should be a single-phase or three-phase model.

Adaptable protection and supply

A single-phase UPS can be regarded as the entry point to this type of system. It has one input, one output and its single sinusoidal voltage is transmitted through a circuit made up of two wires: one phase and the neutral. Its use is generally limited to applications that require reduced power, usually below 10 kVA or, at most, 20 kVA, mainly small domestic installations, offices and shops.

Single-phase UPS systems usually use conventional Schuko-type sockets. As they use a single wire, the risk of overheating limits their power. Their main advantages are an affordable cost and simple installation, often plug & play. By contrast, three-phase UPS systems use three separate conductors that provide individual sinusoidal waves to power loads continuously; hence they require a minimum of four wires: one for each phase plus the neutral. The output, meanwhile, can be single-phase or three-phase. Three-phase UPS systems are used in larger installations with critical loads: from data centres and hospitals to industrial plants and office complexes, as well as for protecting equipment that incorporates motors, such as lifts, pumps and fans. Three-phase UPS systems are usually designed to handle loads above 20 kVA and can reach the megawatt range. Alongside this greater capacity, they are more efficient when distributing the load between phases, meaning that cables can be thinner than with a single-phase UPS. This, in turn, increases the stability and reliability of the supply when power reaches significant levels.

However, the needs of companies and industries often change and therefore require different power configurations. The case of versatile UPS systems for small installations and low or medium power ratings, up to 20 kVA, is particularly interesting, as they can cover both types of installation, always using external batteries to increase autonomy in order to support, for example, a larger number of servers or provide back-up for longer.

The UPS’s greater power capacity can be obtained by connecting several units in parallel, with the additional possibility of providing redundancy in the event of a failure or offering continuity while maintenance tasks are being carried out. Finally, the management of the most critical loads can be customised through segmentation, establishing two priority levels. This prioritisation of supply by the UPS can also be set to take even more crucial measures when, for example, after a certain time has elapsed following a mains supply failure, only critical equipment is powered.