By Michael Brooks, Managing Director, Centiel Ltd

Michael Brooks recently presented on ‘How Close to The Perfect UPS is 4th Generation Modular UPS Technology?’ at Data Centre World. Here, he examines whether the latest UPS technology, if correctly configured, can significantly improve both power availability and operating efficiency.

The perfect UPS is 100% available, 100% efficient, takes up no space, costs nothing to purchase and doesn’t require maintenance. With this in mind, how close is the new 4th generation modular UPS technology to perfection, and what else needs to be done to achieve power protection perfection?

To answer these questions we need to look at where the industry has come from. Thirty years ago, the only way to achieve redundancy was to install a parallel UPS system. These stand-alone systems were large! A 60KVA UPS was the size of a double wardrobe and weighed around 600kg. You needed two of these for a parallel redundant system, plus batteries which were typically at least the same size.

The transformers inside were heavy and utilised copper which was expensive. The units typically, 1VA cost £1 to purchase. So a 60KVA UPS cost £60K and again you needed to double up for a parallel system!

Usually, efficiency was at best around 85%, and they were limited by a mean time to repair (MTTR) of around eight hours needed to fix a fault.

Large, high loss power components required equally large heatsinks and cooling fans to keep them cool. Environmental concerns and greenhouse gases were also not considered in those days. These systems consumed huge amounts of power, were big and noisy, cost a lot of money and required regular, invasive maintenance and component replacement. In other words, the UPS systems of 30 years ago were far from perfect!

In the early-90s, transformerless technology was pioneered by Filippo Marbach and his design team, radically shrinking the UPS units. Whilst transformer-less technology has become mainstream today, at the time, it offered dramatically increased efficiency, decreased size and weight and reduced cost. However, although better power components resulted in improved switching efficiencies and quieter operation, customers looking for system redundancy still required two of these units to ensure a parallel redundant UPS system. It still took hours to fix faults in these single units.

Fast-forward to the modular UPS introduced after the millennium and we see further improvements. All the circuitry is contained within each module, making repair more straightforward and therefore, improving availability as well as reducing system footprint.

Today, the fastest growing market sector we see is mid-range three-phase modular systems. This is because properly configured modular systems simultaneously maximise load availability and system efficiency. Modular systems are increasingly replacing traditional stand-alone and parallel systems with the drive for high availability, fast repair and commonality of parts, as well as reduced system footprint.

The 4th Generation modular UPS systems now available, such as CENTIEL’s CumulusPower, incorporating Distributed Active Redundant Architecture (DARA), provide a significant improvement over previous system designs. Each module contains all the power elements of a UPS – rectifier, inverter, static switch, display – and critically – all control and monitoring circuitry. This places it above other current designs that have a separate, single static switch assembly and separate control or intelligence modules as there is no single point of failure.

Availability for this system is now ‘nine-nines’ or 99.9999999%. This is because the MTTR is around three minutes.

There are other advantages of 4th generation modular technology which takes us even closer to the perfect UPS. Systems in the past only ever reached maximum efficiency when operated at high loads, typically over 80% load. Obviously for the most common parallel 1+1 system, the maximum they could operate at would be 50% to ensure the parallel UPS could take over in the even of failure without overloading. Maximum efficiencies could reach around 80% typically in real world conditions.

From an efficiency perspective, the big challenge is that the IT power requirement in most organizations will change over time. Over a six-year period, a Comms Room with an initial load of 6kW, might easily have expanded to a 30kW load. So how can the infrastructure be built to meet these dramatically changing demands? Put simply, a UPS needs to operate at the most efficient point of its energy curve. A system which is too small will be overloaded, compromising reliability and availability. A system which is too large will waste energy, be inefficient and costly to run. It will also cost more than necessary to maintain due to its size. Scalability and flexibility is therefore an essential consideration when purchasing, to ensure the continual ‘right sizing’ of the UPS.

Our most modern technology now reaches peak efficiency at low loads and the efficiency curve is flat, offering more flexibility. In this way, 4th Generation modular technology such as CumulusPower offers 97% efficiency even at low loads.

Modular also offers the advantage to ‘pay as you grow’ unlike older fixed-size systems. It is also possible to calculate the energy savings when installing new equipment.

A ten-year-old UPS will waste energy at a much higher rate than a modern system, and we are able to quantify precisely the energy and cost saving of a new installation. A recent example was a transport operator looking at replacing a 30kVA UPS running at best at 92% efficiency. A new CENTIEL PremiumTower 30kVA UPS for example operates 97% efficiency. We were able to confirm – with the cost of a system typically running at £0.12p/KWH of power – an annual energy saving equating to £1,874.32. The energy saved meant the new UPS system could pay for itself within six years.

There are further benefits of replacing UPS systems and we should aim to be transparent with clients to enable them to understand these advantages. For example: older equipment is less efficient and the waste energy is produced as heat. This requires more air conditioning to keep it at a suitable temperature. The calculation above actually did not include the increased cost of air conditioning to cool older equipment and so in reality, the actual energy and cost savings would be far higher.

So, UPS technology has seen huge developments over the years. UPS systems have become significantly more efficient, take-up less space and cost less purchase and run, and reliability and power availability have increased. The most modern systems have become about as close perfection as possible, keeping in mind there will always be some losses due to the very nature of power conversion and switiching. There simply isn’t much room for improvemrnt at 97%.

For the future, the next barrier to be tackled to improve UPS systems further will be developments in energy storage technology.

We have seen several attempts over the years to move away from the traditional lead acid battery as the primary energy store for the UPS. We’ve seen flywheels, compressed air, fuel cells, super capacitors, and more recently lithium ion batteries. However, the traditional lead acid battery has steadfastly remained the simple, cost-effective solution for the vast majority of installations.

The increasing use of Li-ion technology in the automotive industry has brought the technology forward a long way, and hopefully will eventually drive down costs with higher volumes once supply shortages have been resolved. It is then likely we will see a breakthrough to the mainstream UPS market.

Incorporating Li-ion batteries will inevitably reduce the size and weight of UPS systems further and the longer useful working life of Li-ion will mean fewer costly replacements. All of which will benefit customers.

However, the charging and discharging characteristics of Lithium ion batteries are totally different from lead-acid batteries and so UPS systems need to be able to accommodate these different characteristics. Therefore, the systems of the future will need to be designed with Li-ion in mind. The good news is that CENTIEL’s technology is already Lithium Ready, so installations with existing lead acid batteries will have the option to upgrade to Li-ion in the future, without needing to replace the UPS.

At CENTIEL UK our goal is clear: to achieve the ultimate availability of power for our client base. Our leading-edge technology, backed-up with our comprehensive maintenance contracts carried out by our experienced and fully trained engineering teams will ensure our clients’ power has the very best protection at all times – whatever the future holds. Have we developed the perfect UPS? Well not quite, but with an average of 3 milliseconds downtime per year for a correctly configured system we are well on the way to achieving power protection perfection.



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