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Exploring the energy saving benefits of modular UPS

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Riello UPS sales manager Chris Cutler explores the evolution of modular uninterruptible power supplies and unveils a major upgrade to their own award-winning Multi Power range.

As we head into the 5G era, demands on data centres and computer processing power are surely set to soar. Even today, the 200 million-plus followers of Cristiano Ronaldo’s Instagram account use 30 megawatt hours of electricity viewing each of the football superstar’s latest posts. 

Data centres in the UK already consume around 2% of all UK electricity. The biggest bit barns having an annual bill upwards of £3 million and using enough energy to power 300,000 homes. 

Industry and technology manufacturers have made great efforts to reduce power consumption and improve efficiency. But there’s evidence that the gains of Moore’s Law are starting to slow. 

Research from the Uptime Institute found that almost two-thirds (65%) of the energy used by data centre IT systems accounts for just 7% of the processing work. This is because of ageing equipment and efficiency improvements plateauing. 

Energy accounts for around 60% of a data centre’s overall running costs. So any efficiency savings across the entire tech stack are welcome, both economically and environmentally. 

Explaining efficiency gains

Thankfully, UPS technology doesn’t stand still. Compared to a couple of decades or even a handful of years ago, efficiency has come on in leaps and bounds.

While there’s still a place in certain circumstances for monolithic, transformer-based UPSs that can only achieve optimal performance and efficiency when carrying high loads of 80-90%, for most applications today there are more efficient solutions.

First, we had the introduction of transformerless UPS systems. Not only are these far more efficient compared to their transformer-based counterparts. But they also generate far less heat so don’t need as much expensive and energy-intensive air conditioning. 

Following this progress came modular uninterruptible power supplies. As the name implies, modular solutions allow greater flexibility and scalability than a standalone UPS does. 

They start with a cabinet that is populated with multiple power modules working together to provide the necessary power and N+1 redundancy. This enables the UPS system to closely mirror the load requirements at initial installation, which reduces the risk of wasteful oversizing and cuts unnecessary energy losses.

Say you’re supporting a 100 kW load with a modular cabinet that holds five 25 kW modules. It shares the load across its 125 kW total capacity. If any of the individual modules fail, there’s still enough power in the remainder to fully support the load without interruption until the faulty module is replaced. 

Such redundancy in this example requires just a 20% increase in capacity compared to the full load. However, to achieve the same N+1 redundancy with a monolithic UPS would need a completely separate uninterruptible power supply in case of failure – 100 kW + 100 kW, or a 100% capacity increase. 

Another major advantage of modular UPS systems is their inherent scalability. As power requirements increase, you simply “pay as you grow” by plugging in extra power modules or adding cabinets in parallel as and when required. 

This vertical and horizontal scalability offers end-users capacity ranging from as little as 15 kW to more than 1 MW plus redundancy in a single UPS system. This helps future-proof their power protection plans for years to come without wasting energy, floor space, or air conditioning.

Power modules are all hot-swappable too. This means there’s no need for any downtime during general maintenance and service visits. 

Relaunching Riello UPSs modular Multi Power

Riello UPS’s own award-winning modular solution has undergone something of a recent revamp. We’re officially unveiling our new and improved Multi Power range at Data Centre World this month (11-12 March). 

The exciting extension sees the introduction of two brand new power modules – 15 kW and 25 kW both 2U in height – to complement the existing 42 kW option. 

We’ve also developed a dedicated cabinet for the new modules measuring just 60 cm wide by 1.2 metres high, delivering 60 kW N+1 (for the 15 kW modules) or 100 kW N+1 (for the 25 kW modules) in a single frame. 

This ensures smaller data centres and other applications can enjoy the same performance, flexibility and efficiency benefits that modular UPSs currently provide high-end data centres with. 

The pair of new power modules sit alongside our best-selling 42 kW version. This is housed in a two metre-high chassis that holds a maximum of seven modules, offering 252 kW N+1 of power in a single cabinet. 

With both the standard and the compact cabinets, up to four can be paralleled together and when the time comes to expand, offering a maximum of 1,008 kW N+1 in a single system. 

While the popular range also includes space-saving combination cabinets containing both power modules and battery shelves. These are an ideal choice for applications needing to balance high power density with a limited footprint.

Extra energy savings

The MPW range is capable of achieving exceptional efficiency of 96.5% in online double conversion mode. It also boasts a special feature that boosts efficiency to around 95% even at low loads of 20-25% without compromising on online UPS protection or redundancy.

Energy Saving Mode keeps the UPS in online operation with the inverter powering the load. The Multi Power’s advanced microprocessors automatically activate the appropriate number of power modules to supply the current load. 

All other modules stay idle with their inverter closed and charger switched off to maximise system efficiency. An inactive module stays in this Energy Saving Mode for up to 15 hours. After that, it swaps roles with another active module so that all modules and components age at the same rate.

If there’s a problem with the mains supply, a fault in any of the modules, or if the total load goes above 85%, all the idle power modules immediately kick back into action to provide online double conversion protection.

It’s important not to confuse Energy Saving Mode with another common operating status – ECO Mode – which in effect sees the UPS run off the mains supply without any of the power conditioning associated with online mode. 

Although ECO Mode offers 99% efficiency, if there’s an issue with the mains, there’s a fractional break in power while the UPS switches back to the inverter. Although this can be as little as 15 milliseconds, that’s enough to cause serious damage in mission-critical settings. 

For that reason, ECO Mode should only be used at sites where the mains supply is stable and at times when any critical loads are inactive. This could be overnight or out-of-hours when essential equipment isn’t running. 

Making the move to modular

The major data centre boom in the UK took place around a decade ago, although thankfully the sector shows little signs of slowing down with several sizeable new installations currently under construction.

Every UPS system has a natural lifespan where it will eventually require replacing. Industry best practice suggests this tends to be between years 10-12. However, there’s a strong case that replacing earlier in the lifecycle can often make financial sense, with the long-term benefits in efficiency and performance more than paying off the upfront cost of upgrading the UPS.

Moving to modular solutions like the Multi Power offer operators the perfect opportunity to do more with less – high power density in a small footprint, maximising their efficiency while minimising waste and their environmental footprint.


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