Riello UPS Business Development Manager, Chris Cutler, explores the evolution of modular uninterruptible power supplies (UPS) and looks ahead to the next stage in their development.

While the first modular uninterruptible power supplies date back to the early 1990s, it’s really during the last decade where they’ve really come into their own. Up until then, most data centre UPS lived up to the stereotype of the big, bulky, inefficient black box sitting in the corner of the server room.

But UPS technology has come on in leaps and bounds in recent years. First came the development of more efficient and lighter transformer-free systems. That was followed by the rapid growth in popularity of modular solutions offering data centre operators far greater flexibility and scalability.

Now we’re reaching the latest stage in this UPS evolution, with advances such as silicon carbide components providing the potential for enhanced energy efficiency and increased power capacity in a further reduced footprint. 

Background to modular UPS

A modular UPS differs from the traditional monolithic unit in that it comprises a frame which you populate with several individual power modules to build up to your required capacity and redundancy. 

Take our award-winning modular range Multi Power, which offers the choice of 15, 25, or 42 kW power modules and various cabinet sizes to ‘build’ with. 

This principle makes it far easier to closely mirror your UPS system at initial installation to the actual load requirements in your data centre, minimising the risk of wasteful oversizing, whilst also controlling your upfront infrastructure costs.   

When your circumstances change and you need more power, you simply ‘pay as you grow’ by adding in extra power modules or more cabinets in parallel.

Say your data centre has a 100 kW load and you’ve got a modular cabinet holding five 25 kW modules. The UPS shares the load across its 125 kW total capacity and if any of the modules were to fail, you’d still have enough power in the remaining four to support the load until the faulty one is replaced – that’s your classic N+1 redundancy. 

In such a setup with a modular UPS you require just a 20% increase in capacity compared to the full load. To achieve the same N+1 protection with a standalone UPS you’d need a separate unit (i.e. 100 kW + 100 kW), a 100% capacity increase, which would also tie up significantly more floor space in your IT room.

Indeed, the vertical and horizontal flexibility of a modular UPS, such as the Multi Power, enables it to offer capacity ranging from as little as 15 kW to more than 1 MW power plus redundancy in a single UPS system. 

Such scalability future-proofs your data centre’s power protection needs without wasting valuable energy, floor space, or air conditioning. 

Every individual power module is hot-swappable too. That means you’re guaranteed downtime-free maintenance during any service visits. Or if you ever experience a fault with any of the modules, you don’t have to power down the whole system while you replace it.

Exceptional energy savings

In addition to scalability, compactness, and ease of maintenance, another major benefit of modular UPS is high operational efficiency, which reduces both your day-to-day running costs and overall environmental impact. 

As explained previously, the principle of modularity enables UPS power capacity to closely mirror the data centre’s actual load, eliminating the risk of wasteful oversizing. Modular UPS are typically transformer-free too, which ensures the highest efficiency possible even in maximum protection online double conversion mode. 

Our Multi Power range also incorporates a dedicated Energy Saving Mode that guarantees high efficiency (95%+) even at low loads of around 20% without compromising on reliability. 

This special operating mode keeps the UPS running in online mode with the inverter powering the load, so you still get maximum protection. But the UPS’ microprocessors only activate the necessary number of power modules to support the current load. The rest are inactive with the inverter closed and charger switched off to maximise overall efficiency. 

A power module can stay in this energy-saving state for up to 15 hours. After that, it swaps with one of the active modules to ensure all components age at a similar speed.

And if there’s any disruption to the mains supply, all the inactive modules immediately restart to provide maximum protection. The same happens if there’s a fault with any of the modules or there’s a sudden increase in your load. 

Modular gains put into practice

We’ve recently replaced a legacy UPS at a Manchester colocation, cloud, and hosting data centre with a Multi Power installation. The original transformer-based UPS system operated at just 85% efficiency, while the new solution can achieve up to 96.5%, a significant improvement. 

Due to the scalable design of the new solution, the client load level sits higher in the efficiency window and as a result will deliver energy savings of around £12,000 a year.

On a similar theme, replacing end-of-service-life transformer-based UPS systems at a leading consumer goods supplier’s two data centres with Multi Power boosted overall UPS efficiency across both sites from 92% to 96%, cutting the customer’s electricity bills by more than £300,000 a year whilst slashing air conditioning by 72%.

Incredibly, these exceptional economic and environmental improvements required less than half the original floor space, with the upgrade to Multi Power actually resulting in a 59% per m² reduction in footprint. Talk about doing more with less!

An eye on the future

So where next for modular UPS? Everyone’s goal is to develop the most efficient UPS system as possible. 

One of the likely key drivers in this ongoing evolution will be manufacturers making greater use of silicon carbide semiconductors, which are far smaller and lighter than the silicon-based components typically used in UPS production. They also produce less heat, which in turn reduces your onsite cooling needs.

The higher efficiency of the silicon carbide components significantly reduces the energy needed to run the UPS and increases its overall performance, enabling it to achieve efficiency around 98% whilst operating in maximum protection online mode. 

That’s equivalent to the efficiency ratings you only tend to see at the moment when the UPS is running in various ‘Eco’ or ‘economy’ modes, where any energy saving always goes hand in hand with a trade-off in reduced protection. 

As the availability of silicon carbide improves, the modular UPS systems of tomorrow will be able to deliver greater capacity at a higher operating efficiency in a smaller footprint than even today’s most advanced solutions.