Networks Europe Nov-Dec 2015 | Page 41

and facilities managers, the respondents ranked energy efficiency fourth in priority. Availability was the overall, overriding concern. This is partly due to the costs of a data centre outage, which can run into hundreds of thousands of pounds. Yet concerns about damage to the enterprise’s reputation are often even greater, and with good reason. A data centre failure that takes out a bank’s ATMs and denies customers access to their accounts is an event that can cause real problems for thousands of users and possibly make the national news headlines. That’s not to say that operators have no interest in energy saving or green branding. They’re certainly interested in achieving these objectives, but only if they can do so without putting their data centre’s availability at risk. Wouldn’t it be great if possibilities existed that allow energy savings to be made without threatening the facility’s availability? In fact, such possibilities do exist, and are currently implemented in m any data centres. Part of the approach involves using sensors and software to monitor and modify the behaviour of a centre’s IT hardware, power and support equipment, and environmental control. Such strategies are complemented by the availability, efficiency and flexibility of the equipment they are working with. This applies not only to the ICT hardware itself, but also to the UPS and cooling equipment that supports it. As UPSs tend to be large-scale devices handling high power levels, their performance can have a significant impact on that of the entire data centre. Therefore, installing UPS systems that are efficient while also being highly available and flexible can make a significant contribution to meeting the twin demands of any data centre – high efficiency with uncompromised availability. Accordingly, we can look at the UPS topologies that allow these objectives to be realised. Modern UPS Technology One of the most important developments in recent years is the advent of transformerless UPS technology. Facilitated by advances in power semi-conductors, it offers several key advantages over earlier transformer-based solutions. Efficiency is improved by up to 5 per cent and remains consistent over the entire load spectrum. Power factor becomes closer to unity and independent of UPS loading, reducing the input current magnitude and allowing reductions regarding cabling and switchgear sizing and possibly reducing electricity costs. Input current harmonic distortion is also reduced. However, one of the main advantages is the huge reduction in size and weight that transformerless technology allows. The UPS footprint can be halved, while its weight reduces by about 75 per cent. These reductions are so significant because they have facilitated the concept of modular UPSs and a completely new approach to UPS implementation. Instead of a large, UPS AC-DC efficiency curves – transformerless v. transformer-based www.netcommseurope.com A modular system can be configured to the existing load requirement single, inflexible floor-standing module, a UPS can be built up as one or more complete, self-contained modules in a 19” racking frame. This is demonstrated in UPS Ltd.’s PowerWAVE 9500DPA high power UPS. It can start as one frame containing a single 100 kW module; the frame can then be scaled vertically in 100 kW steps up to its 500 kW capacity. If preferred, the system can be run in redundant mode, supporting a load up to 400 kW in an N+1 redundant configuration. Horizontal scaling is also possible – this means that up to six frames can be paralleled to provide up to 3 MW power capacity. The modular design permits UPSs with very high power availability, particularly if they support ‘hot swapping’. A module is hot swappable if it can be inserted or removed from the host UPS frame without depriving the critical load of power or transferring it to the raw AC mains supply. Safe electrical disconnection and isolation without the risk of error-induced NETCOMMS europe Volume V Issue 6 2015 41