Choosing Between Different Types of Uninterruptible Power Supply

by : Alison Campbell

Business processes these days increasingly rely on technology, which by default relies on a clean and reliable source of electricity. As more and more industries turn to computerization, mechanization and automation, an unprecedented strain is being placed on already overworked electricity infrastructures around the world. It has taken the developed world by surprise. Managers are now faced with the real prospect of energy rationing and power supply issues. If any part of their business cannot continue without electricity, they have to find alternative ways of securing supply and/or generating their own. Making the correct choice of uninterruptible power supply (UPS) is now more important than ever.

What's an uninterruptible power supply (UPS)?

A UPS sits between the mains supply and 'the load' (equipment and systems in a building or datacenter that need a continuous source of electricity). At its simplest, a UPS conditions electrical current, converts it from AC to DC, and negates potentially harmful power problems including sags, surges, brownouts and fluctuations. In the case of a total mains power outage, the UPS powers the load from its back-up battery until another energy source starts up. Put simply, an uninterruptible power supply can mean the difference between life and death for some businesses.

Different types of UPS

There are three primary types of uninterruptible power supply:

&bullOnline or Double Conversion

&bullLine Interactive

&bullOffline (or Passive Standby).

An Online or Double Conversion UPS maintains voltage and frequency variations within prescribed limits so output is independent of supply fluctuation. As well as conditioning mains power to negate problems, this is the only UPS solution that provides break-free supply to the plant or datacenter during a power outage.

A Line Interactive UPS uses built-in passive electronic regulation devices to stabilize and regulate voltage fluctuations. When mains supply power is present, the output frequency of the UPS tracks the input of the mains. Line Interactive and On-Line UPS use tower or 'rackmount' case formats and sit next to their respective loads, typically in a datacenter or computer room.

An Off-Line or Passive Standby UPS is a compact device designed for desktops or wall mounting, which uses its own output to track voltage and frequency variations in the mains supply power.

Extended UPS benefits

As well as obvious continuity and power conditioning advantages for a datacenter or computer room, larger uninterruptible power supplies can work in parallel to improve system resilience, MTBF (mean time between failure) and availability.

For a network-sized uninterruptible power supply, the installation of an external UPS maintenance bypass enables routine or emergency maintenance to be carried out (without supply disruption) during normal working-hours.

Extended runtime (the time a load is running on back-up power) can be provided by a combination of extra battery packs and an external standby power source such as a generator or fuel cell.

The transformer-based UPS system

While many UPS are transformerless, organizations reliant on larger datacenter and voice networks, industrial processes, security or hospital applications, often require transformer-based uninterruptible power supply. This gives greater robustness, albeit with slightly lower efficiency and greater heat and noise generation.

Essential protection against power outage and rationing

As well as industrial processes, uninterruptible power supplies may be used to protect large site-wide installations. From the smallest desktop units to the largest parallel redundant installations, a correctly sized, reliable UPS system, provided by an established manufacturer such as Riello UPS Ltd, offers essential protection against the growing risks of power outage and power rationing.