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Mission Critical Power

07 Feb Mission Critical Power Interview: Are data centres using their UPS estate efficiently?

The latest research suggests that many UPS systems are not operating efficiently and are being under-utilised.  This month, Riello UPS general manager Leo Craig, spoke to Louise Frampton, editor of Mission Critical Power Magazine about the potential for modular UPS to help data centres balance resilience and efficiency by offering scalable solutions.

Riello UPS conducted extensive research looking at 2,268 UPS systems between 10 and 800kVA that were serviced during 2015-16. More than 50% were found to be running at less than 50% load. In addition, about 25% of the UPS estate was found to be running at 20% load or less.

Currently, any online static UPS must meet certain efficiency levels at set percentage load levels to qualify for inclusion onto the Energy Technology Product List (often referred to as the ETL). This is a government-managed list of energy-efficient equipment and is part of the Enhanced Capital Allowance (ECA) tax scheme for business. The load levels outlined for UPS are 25%, 50%, 75%, and 100%, with the highest efficiency rating at 100%.

The research showed that only three of the UPS exceeded the 75% loading and none exceeded 85% total load. The UPS included standalone, parallel redundant and N+1 and modular systems. Looking at the data, a significant number of UPS were found to be running at partial load, which would suggest that higher efficiencies at lower loads would bring energy saving within the UK’s UPS estate.

Riello UPS general manager Leo Craig comments: “At 25% load, UPS systems do not have to meet such stringent efficiency targets and can be 93% efficient to qualify for ETL. Although many data centres can qualify to claim back tax, therefore, they are using their UPS inefficiently. Furthermore, it is our view that the 100% load level should be dropped as a marker, as no UPS should be run continuously at 100% load – it is accepted within the industry that this is bad practice and presents a significant risk to the user.”

Craig adds that current best practice is to load the UPS up to 80%. If you have a parallel redundant system (ie one operational and one as back-up), the load would be set at 40%. However, Riello’s research would suggest that many are being used at less than 20% and energy is being wasted.

“The government, at present, views this as acceptable, since the ETL categorisation suggests that low loads of 20% are an efficient use of UPS. This is wrong,” Craig explains.

“The government needs to change its stance on this and improve the ETL, as the benchmark is driving the wrong behaviour. Furthermore, efficiency at 100% load is simply meaningless. Using the analogy of a car, it is the equivalent of saying that you are most efficient when driving at 120mph, when the speed limit is only 70mph and realistically most people only drive at an average of 45mph.”

Last year, Frost & Sullivan recognised Riello UPS with the ‘Global Frost & Sullivan Award for New Product Innovation’ for its Multi Power (MPW) UPS. Since its launch, the modular solution has been well received by data centres across a wide range of markets in the UK and Europe. A factor in this growing interest has been its ability to address some key issues facing data centres – in particular, that of UPS estate being under-utilised.

The modular approach provides a solution to address the problem, he explains, as it is possible to either scale up or scale down. Data centres can easily switch modules off, to avoid the UPS being under-utilised, and therefore operate the UPS more efficiently.

“The trend for virtualisation and consolidation in the data centre has led to a reduction in the number of servers, sometimes by as much as 50%,” says Craig. “This rapid change meant that data centres had to move from running at full design capacity to running at potentially half the design load, practically overnight. The original UPS systems in place were designed for 80% loading and subsequently had to run at less than 40% load – and are now operating very inefficiently. Faced with a similar scenario, a modular system would simply allow the system to be scaled down to meet the change in demand of the data centre to optimise efficiency.”

He adds that when designing data centres, the future capacity is frequently over-estimated. A modular solution has the flexibility to scale up the power ‘in blocks’ as capacity increases over time, perhaps starting with 100kW on day one, then increasing to 300kW or 400kW or even 1MW as demand increases.

The MPW allows the UPS power and redundancy level to expand vertically from 42kW to 294kW in a single power cabinet. Likewise, the power capacity can be horizontally scaled up from 294kW up to 1176kW by connecting up to four power cabinets in parallel. The battery cabinet is designed to house up to 36 units within a single frame, with a maximum of 10 cabinets connected in parallel.

The power cabinets feature two separate microprocessors performing distinct duties of regulating the overall UPS operations and managing end-user communication. In addition to these, it employs three dedicated communication buses to manage and transmit the data, and up to four temperature sensors are embedded within the power cabinet to enable constant and efficient operation.

The MPW is designed to offer full-rated power, especially for unity power factor loads such as the latest server generation applications. It can achieve this without any power downgrading, even when operating at temperatures up to 40°C. It guarantees system efficiencies of more than 96.5% while operating in online double-conversion mode, and an efficiency in excess of 95% even at 20% loads, ensuring extremely low losses.

The MPW has also significantly minimised the upstream power source rating requirement by reducing the input harmonic pollution. Furthermore, Riello UPS has effectively addressed the issue of failures due to miscommunication between the component parts of the system by doing away with the traditional method of controlling the power modules through one microprocessor. Instead, it employs multi-microprocessors and assigns specific functions to each.

Modular UPS provides an ideal solution for new builds, as it is often very difficult to predict what the future load will be. However, Craig suggests that modular may also be a suitable solution for replacing older UPS.

“The UPS is your insurance policy. If you drove an old car from London to Edinburgh, chances are it would break down. With ageing UPS, there is an increased risk of it failing. After seven to 10 years, it is time to consider replacing the UPS. The return on investment will depend on the application, but there are benefits around power density, when choosing a modular solution. In a data centre, space is money. You do not want to waste space with large UPS,” he comments.

The MPW system offers very high power density; it has the maximum amount of kW per square metre. Because it is so compact, floor space is saved – freeing up room for more servers, which is crucial for revenue generation.

The top priorities for data centres continue to be resilience and efficiency – the challenge for this sector is to balance these effectively, as Craig points out: “Normally, if you increase your resilience, your efficiency goes down, because energy costs money. If you are wasting energy, you are throwing your profit margin away. Data centres need a resilient solution that is also efficient, and this is where a modular solution can help, as it meets both requirements,” he asserted.

Craig adds that modular solutions also offer flexibility. Whether co-location facilities or company specific, data centres are unable to predict what is around the corner in terms of what will be required in computing power. Smart devices are fuelling huge demand on data centres and this is only going to increase. Data centres will be expanding at an incredible pace to meet the need for increased processing.

Ultimately, increasing interest in modular solutions will be driven by the ability to optimise both the initial investment and the total cost of ownership by growing along with the demands of a business, while preventing data centres from having to oversize the UPS.

Click here to view the full interview with Leo.