The Stack Archive Feature

UPS basics: UPS modes of operation

Mon 9 Jul 2018


Did you know an uninterruptible power supply (UPS) offers far more than simply providing reliable backup in case of electrical emergency? Riello UPS’s latest ‘UPS Basics’ video explores the different modes of operation available on many modern UPS units.

UPS technology is constantly evolving and developing. For example, we’ve recently highlighted the increasing popularity of modular UPS systems, which provide premium power protection and performance even though they need less energy and space than traditional static units.

Similarly, the modern UPS isn’t simply a safeguard against disturbances and disruptions to the mains supply, although in critical environments such as a data centre that is, of course, their primary role.

Today’s power protection equipment is versatile and capable of several roles and functions. But what do the various UPS operating modes do? And when should data centre operators use them?

UPS modes

This brief ‘UPS Basics’ film outlines the modes of operation you’ll typically find on a modern UPS unit:

  • Online UPS: as we learned last week, an Online UPS uses double conversion technology to provide optimum power protection in the most critical environments. With an online UPS, the load isn’t directly connected to the mains supply.
  • ECO mode: in this UPS operating mode, the inverter remains switched off as long as the mains supply is within tolerance. Running in this mode offers maximum energy efficiency, although if there’s an issue with the mains supply the load experiences a short break in supply whilst the UPS switches back to inverter, so it isn’t suitable for every power-critical situation.
  • Voltage stabilisation: the UPS operates in online mode, but no batteries are connected or charged. The reason for this is so the unit maintains a consistent voltage to the load, irrespective of the condition of the incoming supply.
  • Frequency converter: predominantly for imported equipment or machinery that runs on a different frequency to the UK mains supply. It enables the output frequency to differ from the UPS input frequency. However, when running in this mode, the UPS’s internal bypass must be disabled.
  • Standby off mode: suitable for loads such as emergency lighting, which do not require power unless the main supply fails.
  • Smart active: a hybrid of online and ECO modes. Depending on the stability of the incoming load, the UPS decides which mode to operate in. If the load is unstable, the unit runs in online mode for premier protection. Stable loads switch to the energy-saving and efficient ECO operating mode.

It goes without saying that it depends on the manufacturer and specific model of uninterruptible power supply as to whether all of these operational modes are available or not.

Next week sees the final part of our ‘UPS Basics’ mini-series. We conclude with a guide to choosing the most suitable uninterruptible power supply for your data centre. Until then!

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