UPS units come in two different formats: single phase and three phase. Single phase uninterruptible power supplies typically cover requirements up to 20 kVA  and are widely available in homes or lower power equipment. Three-phase UPSs are mainly used in large installations, such as data centers, and large industrial power applications with higher power .

Single-phase UPS System

A single-phase system refers to a single input source and a single output source that provide a 1:1 ratio for the use of electrical equipment. Single-phase power supplies are used in smaller installations, such as rack-mounted servers, telecommunications, network switches, computer systems, or any equipment that runs from a standard three-pin UK plug or buildings that only have single-phase power-making them ideal for small Application business! If the power protection products are described as single-phase, it means that they can be protected by a single AC waveform or pass the power supply, which can usually meet the requirements of up to 20kVA. 

Kstar single-phase ups system for reference: 

Featured with DSP-controlled technology, high input & output power factors, ECO mode for energy saving and compact size desigh, Kstar UDC series single phase UPS is an ideal solution to your computer center, network center, communication system, automatic control system or other critical systems, which is demanding for a thorough protection.

Three-phase UPS System

Three-phase UPS systems are usually used in places that needa large amount of power to critical loads (such as data centers, medical theaters, and large industrial units) and equipments with motors usually require three-phase power. Such as elevators, water pumps and fans. A three phase electrical supply is a combination of three single phase supplies with a neutral connection, with their wavelength connected at 120° phase rotation between them.. Three-phase power is delivered from the power supply to the service entrance of the building, and then divided into three separate single-phases, and delivered to electrical equipment as needed, or directly to any three-phase equipment. A commonly used analogy for describing differences is to imagine a three-person rowing team in contrast to a one-person rowing team. In a three-person team, there is always at least one oar in the water at any time to provide constant power for the rowing boat.

Kstar three-phase ups system for reference:

YDC3300 series UPS is a three phase in and three phase out high frequency UPS with medium and large power capacity, higher power density, smaller footprint, which takes the leading position in the UPS industry with same power capacity.