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Super-efficient UPS in a low carbon world

Image: Adobe Stock / Connect world

In an increasingly environmentally-aware age where efficiency is almost as important as availability, Chris Cutler of Riello UPS examines the consequences for the next generation of uninterruptible power supplies.

There’s hardly a week gone by in recent months where the activists from Extinction Rebellion haven’t launched their latest audacious campaign in the fight against climate change. 

It’s debatable whether the Government bowed to this and wider public pressure or not when it pledged to become the first major developed economy to enshrine in law a commitment to achieve net zero carbon emissions by 2050. 

What’s indisputable though, is that resource efficiency isn’t just an optional extra or nicety for us working in the power industry any more, it’s the top priority alongside system resilience. 

Economic and environmental benefits

Electricity is one of the biggest operating costs an IT business has. Indeed, power and cooling typically accounts for between 40-60% of a data centre’s total expenditure. Needless to say, any inefficiency quickly adds up, resulting in higher than necessary energy bills.

There are other implications too. Organisations today are compelled to comply with increasingly stringent government rules and regulations on curbing carbon emissions. 

Then there are growing pressures – from shareholders, customers, and even employees – for businesses to take their environmental responsibilities seriously or face up to the consequences. 

The good news is that UPS efficiency has improved significantly over the past decade or so. Advances in semiconductor technology and the introduction of IGBTs (Insulated Gate Bipolar Transistors) eliminated the need for sizeable step-up transformers, ushering in the era of transformerless UPS systems. 

These types of uninterruptible power supply offer substantial efficiency improvements (around 5% higher compared against transformer-based systems). They also have a flatter efficiency curve, meaning that they are more efficient at lower loads – many transformerless UPS these days can achieve 95%-plus efficiency even at loads of just 20-25%.

And because they don’t include any bulky, heat-generating transformers, they require far less energy-intensive air conditioning to keep cool, another way to keep electricity costs – and waste – down. 

Efficiency isn’t just about energy use

While reduced power consumption is a key characteristic of modern UPS, efficiency shouldn’t just be viewed through the prism of electricity and energy use. 

Resource efficiency comes in many forms, with how to most effectively utilise server room space one of the main dilemmas data centre operators and facilities managers face. 

In years gone by, UPSs were bulky, heavy, and noisy pieces of kit – the stereotypical big black industrial box in the corner of the room. Fast forward to today, and thanks to the rise of transformerless and modular systems, a UPS can deliver the same power as in decades gone by in a fraction of the footprint.

Another recent advance is that many UPS now offer easy front panel access for servicing and maintenance, eliminating the need for rear entry. 

These developments offer operators greater flexibility in terms of installation (i.e. units can go right up against the wall or even back-to-back), minimising the amount of space needed for the UPS system and ensuring more room for server racks or other equipment. 

From power protection to power management

As society weans itself off coal and other fossil-fuelled power generation, our electricity grid is evolving from a single over-arching entity into a dynamic and distributed network of smart grids. 

With renewables and battery storage playing an increased part in keeping the nation’s lights on, rather than controlling power generation to meet demand as we’ve done in the past, demand will be controlled in real-time to meet the supply. Energy users will be producers too, with electricity flowing in both directions as they feed power back into the grid.  

This calls for a rethink of the role of uninterruptible power supplies and a move away from just power protection to a wider emphasis on power management. 

Partnering a UPS with premium batteries plus advanced communications and monitoring software transforms it into a ‘virtual power plant’ capable of demand side response, helping to support the wider energy network, cut energy bills, and even earn revenue by selling surplus electricity back to the grid. 

The next generation of super-efficient UPS

One uninterruptible power supply that combines all three of these qualities is the new and improved NextEnergy (NXE) series. 

First introduced in 2017 with 250 kVA and 300 kVA versions, a 400 kVA model followed earlier this year. This expansion was accompanied with a raft of upgrades, one of which has seen the footprint of the NXE 250 reduced by a third (0.68m2 compared with the original’s 1.02m2).

The three-phase, transformer-free NextEnergy series delivers unity power factor and TÜV-certified operating efficiency up to 97%. It incorporates a whole host of energy saving features including an Efficiency Control System (ECS) that optimises the performance of parallel installations according to the load and redundancy.

Because the NXE has a slightly higher operating efficiency at, for example, 50% load than at 20%, in an installation with four 300 kVA units, the ECS will automatically choose to run just two of the units at 50% load (96.6% efficiency) rather than having all four operating at 20% (95% efficiency). This equates to a 16% reduction in wasted electricity. 

The NextEnergy also offers a choice of eight operating modes, including the maximum protection of Online, an ECO mode which offers up to 99% efficiency when carrying less sensitive loads, Voltage Stabiliser for power conditioning, and a brand new Active ECO mode.

This latter function performs as an active filter that reduces harmonics and eliminates the need for any power factor correction, meaning it offers higher availability than ECO mode but at a higher efficiency (98.5%) than Online, the ideal middle ground.

In addition, the NXE features forced front-to-top smart ventilation and complete front panel maintenance access, which eliminates the need for rear clearance. This allows for installation in virtually any configuration (against the wall, in a corner, side-to-side, back-to-back) so facilities managers can easily make the best use of their floorspace. 

This versatility stretches to the fact that the NextEnergy doesn’t require a neutral connection, so can work with either a three or four-wire distribution system. 

Thanks to its combination of exceptional performance and efficiency, the entire NXE range has earned a place on the Energy Technology List (ETL). This is a government scheme that encourages businesses to buy ‘best in class’ energy efficient products by enabling them to offset 100% of the cost against their taxable profits. It secured inclusion on the list after exceeding strict energy efficiency thresholds across a range of load ratings. 

Just another reason why the NXE is the next generation of modern, efficient UPS. 

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