Datacentre Ready Modular UPS Systems

With more and more uninterruptible power supply manufacturers launching modular UPS systems, you would be forgiven for thinking that the market is veering towards this type of power system at a fast pace. The topology offers a number of unique benefits and solves a number of specific datacentre critical power issues but there is a cost and this has to be weighed up agains the benefits. A modular UPS system can have a 15-25% price premium of a traditional mono-block type system. This is due to a higher component count and lower manufacturing volumes compared to traditional systems.

For a UPS market where the buzz has been all around ‘efficiency’ for the last few years, going ‘modular’ offers uninterruptible power supply brands something new to fuel their PR campaigns with. Some UPS companies manufacture their own systems, from either their own R&D or bought-in technology. Other UPS suppliers simply import. As usual it’s hard to tell in this industry with the amount of badging that goes on. UPS manufacturers leading the ‘modular march’ include: Kohler/Newave, Riello UPS, Eaton, Huawei and Eltek (Delta Electronics) – all available through EcoPowerSupplies.com. Over the last 3 years we have installed a number of modular UPS systems within a specific segment of the datacentre market – namely universities and call centres running their own datacentres and with the budget to spend on a system they can upgrade and scale when required.

In the industry we tend to classify datacentres by size and according to the number of physical (not virtual) servers they run. The generally accepted classifications are: Micro, Small, Medium and Large. Most companies for example run a Micro datacentre. The table below matches size to number of servers and the typical UPS system size, in terms of kilo-watt (kW) rating installed.

Kilo-watt is used in place of kVA as almost all modular UPS designs are Unity Power Factor rated (1) where kW=kVA. The kW ratings shown are the overall size of the modular UPS system. These will be made up of a frame same (e.g. 120) that can take a number of specific modules. So a 120 frame may take 3×40kW modules maximum either as 40kW, 40+40kW (N+1 or 80kW) or 40+40+40 (N+1, N+2 or 120kW) and so on. Most modular UPS systems have single module ratings of 25-30kW or 40-50kW and these are in 3U slide in modules. Power ratings up to 100kW and potentially at only 2U high are on the horizon during the next 2-3 years.

In terms of datacentres the table becomes a little more self-explanatory when we consider datacentre Tier-rating. This is a concept from the Uptime Institute identifying availability based on the levels of redundancy and resilience within the facility. There are four classifications with 1 being the starting point and 4 the highest level achievable. If you’ve heard of the ‘Five-9s’ concept, this is where it is most applicable within the datacentre industry as a measure of availability:

So the higher the Tier rating, the higher the availability and the lower the expected downtime per annum. However, the higher the Tier rating, the higher the capital (and running) costs in terms of investment in power and cooling systems.

The data for the table is based on experience, client installations and surveys and it provides an indicative guide to the ‘sweet spot’ for modular UPS systems – the small to medium sized facility. Modular UPS costs are too prohibitive for Micro datacentres. For large datacentres costs can also be high compared to a parallel set of mono-block UPS systems.

Modular UPS System Advantages

What the modular approach provides very easily is scalability as with any UPS system this is only true if the original installation is well planned and installed. A mono-block system can provide parallel capabilities and upgradability but the footprint will be greater, the electrical installation and future scalability more complex, with longer service times and swap-out issues if a UPS system develops a fault condition. In summary the advantages of a modular UPS system are:

• Footprint: single tower cabinet into which UPS modules can be placed
• Scalability: easy to add more UPS modules into available frame space
• Resilience: easy to increase/decrease resilience with slide-in modules
• Service: up to 50% plus shorter service times
• Swap-out: fast swap-out with a slide-in module
• Electricals: less complex electrical works provided initially planned for

Modular UPS Systems Pricing

Modular UPS systems have yet to reach parity with traditional mono-block type UPS and may never do so. This is down to two principle factors:

• Volume: the worldwide market for modular UPS is less than 20%. Manufacturers are simply not producing sufficient quantities in order to drive down the costs.
• Component Count: there is a higher component count. Firstly there is more metal. A modular UPS system has to have a frame cabinet to house the electrical connections and bypass arrangements. Typical frame sizes may be 120, 240, 480 and so on into which you can put 40kW modules. Then each module also has some duplication of components in terms of static bypass arrangements, microprocessor controls and ‘hot-swap’ connectors.

Will modular UPS achieve a greater adoption in the market place? Time will tell but in a highly competitive market this can only happen with scale economies and price reductions or a further technological leap in UPS technology. So far, we can report that our modular UPS clients are very pleased with the systems they have installed. Those with multiple datacentres like the fact that they can also carry a spare UPS module onsite which can be used in any of their UPS systems. There is no doubt that modular UPS will continue to develop and grow their share of the uninterruptible power supply market.

For more information see the modular UPS systems ranges we supply or contact us for a free site survey.