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UPS Design Which type of uninterruptible power supply gives the best data protection?

| Author / Editor: Nigel Charig / Florian Richert

There are broadly three types of static, or solid-state, uninterruptible power supplies available: Off-line, line-interactive, and on-line. Here, we look at these topologies and their relative merits.

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Different power supplies all have their relative merits.
Different power supplies all have their relative merits.
(Source: Public Domain / Unsplash)

Practically all organisations today depend on sets of sensitive electronic equipment to handle their everyday IT, communications, and automation functions. As such equipment is susceptible to electrical power glitches or failures, uninterruptible power supplies (UPSs) are normally built into power distribution networks to provide protection from such events.
If a power failure does occur, the UPS battery takes over and continues to support the UPS’s critical load until either

  • mains power is restored
  • or a local generator can start up and take on the critical load
  • or the critical load can be shut down in a safe and orderly fashion

However, while UPSs are therefore highly desirable if not mandatory, their precise design and level of protection depends on each organisation and their individual circumstances. For a data centre or high street bank, for example, the consequences of any service interruption could be so severe that the best available UPS protection must be installed; cost is not the key consideration. Other organisations, though, may not have such critical or sensitive equipment, and will seek to balance their UPSs’ performance against capital and operating cost considerations.
UPS suppliers have responded to this diversity of requirements by offering three UPS categories: Off-line, line-interactive, and on-line. All share conceptually common components, but vary in terms of their topologies. If we start by looking at the generic UPS components, and then at how they can be combined for each category, we can understand how users can match the choices available to their particular priorities.