Home > Kohler Uninterruptible Power > How UPS efficiency can contribute to data centre PUE

How UPS efficiency can contribute to data centre PUE

Kohler Uninterruptible Power News and PR from Kohler Uninterruptible Power - Published 30 August 2017 Improving UPS efficiency can help to better data centre PUE performance. The article discusses the options for this available to UPS operators who invest in the right, transformerless technology UPSs.
As data centre size, energy costs and green legislation demands increase, so does the pressure to improve efficiency in data centres. One popular metric for checking this is Power Usage Effectiveness, or PUE, which was first introduced in 2006 and then promoted by the Green Grid in 2007.

PUE compares a data centre’s total electrical energy consumption – when power conversion, cooling, lighting and other overheads are accounted for – with the amount taken by the ICT equipment performing useful data processing and communications tasks. It is expressed as:

PUE: Total Data centre energy/ ICT equipment energy.

This means that an ideal data centre would have a PUE of 1, where all incoming energy is consumed by useful computing tasks. While real facilities cannot attain this value, they have been approaching it steadily over recent years. Google’s entire fleet of data centres has achieved a comprehensive trailing 12-month PUE of 1.12 for all seasons, including all sources of overhead.

There are limitations to be considered when applying PUE or comparing data centres. For example, data centres around the world are subject to widely varying climactic conditions. A facility in a hot country will have a large cooling load compared with an identical installation in a more temperate zone. This is significant, as cooling can account for up to 30% of a facility’s power. Loading on the data centre’s servers is also a factor, as server utilisation levels affect efficiency.

UPSs and PUE

In Google’s PUE calculations, as well as those of most other operators, the UPS installation is considered as part of the infrastructure overhead; therefore, improving its efficiency will reduce PUE. Accordingly, let’s look at the UPS efficiency options available to data centre operators.

The first step is to review your UPS installation, as it may have some surprises. It could be older than you think, and possibly using transformer-based technology rather than the transformerless approach that has now replaced it. This has significant energy implications, as eliminating the transformer increases UPS efficiency by around five percent, and possibly more if the UPS is only partially loaded.

Some modular UPS systems also offer a smart operating mode – known as the Xtra VFI mode on UPS Ltd’s PowerWAVE 9500 DPA – which automatically switches excess modules to standby if the load drops. They remain on standby and ready to resume active operation immediately if the load recovers or the mains fails. This measure is especially effective for loads of less than 25 percent of full capacity.

Another possibility, suitable for some but certainly not all installations, is to run the UPS in Eco mode. Power from the incoming mains supply bypasses the UPS conversion stages to feed the load directly by default. Eliminating power conversion losses allows UPS efficiency of up to 99% to be achieved, but loads are exposed to any mains-borne spikes or other problems during normal operation.
Improving UPS efficiency can contribute to better data centre PUE performance.

Other announcements from Kohler Uninterruptible Power

  • Understanding your UPS batterys amp-hour rating

    If youre specifying a UPS system, then its absolutely essential that you truly understand its battery autonomy; for how long will it support the load if the AC supplies fail?

    14 May 2018

  • Keeping UPS availability high

    When data centre operators invest in UPS systems, its for one purpose only; to maximise power availability for their facilitys ICT equipment.

    14 May 2018

  • Future trends for UPSs

    What does the future hold for UPS technologies and systems? We asked Alan Luscombe, Director at UPSL, for his views, as summarised below.

    02 Nov 2017

  • UPS, heal thyself

    UPSs exist solely to deliver clean, uninterrupted power to their critical load but their ability to do so is entirely bounded by their resilience to failure of their own components or subsystems.

    31 Aug 2017

  • Maintaining UPS efficiency when the load size diminishes

    Modular UPS technology, as implemented in systems such as UPSLs PowerWAVE 9500DPA, is now being exploited in a smart solution that maintains UPS efficiency even when the UPS load is severely reduced.

    30 Aug 2017

  • Is it time to consider Lithium-ion batteries?

    Why hasnt the industry adopted lithium-ion solutions with greater enthusiasm, and is this likely to change? We can answer these by looking at factors relating to both lead-acid and lithium-ion bat.

    30 Aug 2017

  • The Internet of Things, data centres, and UPSs

    The Internet of Things (IoT) is gaining traction at an accelerating pace; Gartner has predicted 26 billion connected devices by 2020, while others are calling even higher numbers.

    30 Aug 2017

  • Director's Blog: So just what exactly is a UPS?

    This blog written by Alan Luscombe, UPS Ltd Director, explains what a UPS is, as well as putting the various risks averted by UPS systems into perspective.

    03 Aug 2015

  • Choosing a generator for data centre power protection

    UPS generators are no longer just a backup plan. Today, they are considered a vital component of a companys power protection policy, as sizing UPS batteries for protracted power blackouts is simply uneconomic and impractical. In choosing a generator for a data centre or other critical IT load application, a number of factors must be considered. These include the generators key components, environmental issues and the qualifications of the suppliers as well as compatibility with the UPS to be supported. In this article, Alan Luscombe, director at Uninterruptible Power Supplies Ltd., a Kohler company, discusses how generators work with UPSs, and the factors you must consider when choosing a generator as part of your power protection policy.

    23 Jul 2015