How To Improve UPS Efficiency Figures

We recently completed an upgrade of UPS installation in a university datacentre. The IT Manager has seen a 50% saving in energy usage by moving from a transformer-based UPS to a modular UPS system. This saving was more than double that anticipated and results from several factors that will have a bearing on any site looking to upgrade an existing UPS system.

Energy efficiency is the ‘hot topic’ for many system components within a datacentre and nearly all manufacturers provide a range of energy saving features with their systems be they servers, coolers or uninterruptible power supplies. The modern UPS system is a very energy efficient system and most will hit around 96.5% or greater in on-line protection mode and over a fairly wide load range of around 25-100%. Other features that you could find built-into your UPS and especially modular UPS systems like the Eaton 93PM, Huawei 5000E, Riello Multi Power modular UPS include module load sharing and sleep modes.

Within a modular UPS, the onboard algorithms will monitor the load profile and decide how to efficiently provide continuous power. This could mean sharing the load across a number of UPS modules and allowing other modules to enter an energy saving ‘sleep mode’. As soon as the load profile changes, the ‘sleeping modules’ are awakened to instantaneously play a role in sharing the load. With a near fully charged battery, battery-charging circuits can also be turned off. This allows the UPS batteries to slowly discharge over a 7-10 day period down to a preset threshold at which point the charging circuit is reactivated. So a modern transformerless UPS is very energy efficient, whether it is a mono-block or modular design. The systems are designed with high-energy efficiency as one of the key design criteria.

For older transformer-based UPS systems, designed up to 10-15 years ago energy efficiency was important but not always seen as a high priority item compared to energy efficiency and parallel scalability. As long as UPS system was robust and could deliver around 92-93% on-line efficiency it matched the market requirements of the day. In order to drive up energy efficiency more advanced transformers were introduced that where slightly smaller in physical size than their predecessors and IGBT-based rectifiers became the norm in favor to 6-pulse or 12-pulse rectifiers. Whilst UPS manufacturers were able to improve the energy efficiency of transformer-based UPS systems, little could be done about the standing losses of lowly loaded systems. The efficiency curve of many systems would simply start to collapse from around 40% loaded or less and could drop as low as 70% or more.

In summary, if you are upgrading from a transformer-based UPS system you will see significant savings in energy usage. Especially of the uninterruptible power supply is not loaded near to its optimum level of 80% or more. Savings will also be possible when upgrading from an older transformerless UPS but not to the same degree. In addition to reduced energy consumption, a UPS upgrade will also provide you with a more advanced diagnostics and remote communications, superior battery management features and the potential of a 3-5 year extended warranty period.

If you would like to discuss a UPS installation upgrade, please call our team on 0800 210 0088 who will be pleased to arrange a site survey for you.