A static UPS might be a no brainer for today’s data centre power protection needs, but replacing a DRUPS is a complex, high-stakes procedure
As innovative applications such as big data and IoT increasingly become the bedrock of global business operations, the need for data centre power protection has never been more critical. Although the effects of downtime vary from industry to industry, in extreme cases, a single outage can translate to millions of dollars of lost revenue.
There are a number of devices that today’s data centres rely on for power protection, but chief among them are uninterruptable power supplies (UPS). UPS serve two essential functions. First, to help protect ICT equipment from power abnormalities on the main supply, and if the mains supply fails, to step in and support the critical load until the mains is restored or replaced by an alternative supply such as generator. By ensuring continuous power supply, UPS help eliminate the danger of costly power outages.
UPS come in two architectural varieties: static and rotary. The former derives its name from the fact that there are no moving parts throughout its power path (static UPS’ rely on chemically stored battery power in the event of downtime). Rotary UPS, as you might have guessed, utilise rotating components to transfer power to the load. As rotary UPS have low redundancy (10-15s), in data centre environments, they are typically coupled with a diesel generator (DRUPS) to provide the necessary redundancy.
Pros and cons
For data centre applications, static UPS provide numerous benefits over their rotary cousins. First, as rotary UPS contain more mechanical components, they are significantly heavier beasts. A 1MVA static UPS weighs in at around roughly two tonnes while a DRUPS equivalent weighs close to 25. Hence static UPS provide greater location and transportation flexibility throughout their life cycle, take up significantly less space, and require fewer human resources to install. You can’t place 25 tonnes on or outside a building without employing dedicated civil and structural engineers.
When it comes to maintenance, their comparatively diminutive form-factor also means planned and unplanned maintenance is less invasive, this translates to reduced disruption, potentially less costs and greater uptime. And as rotary UPS’ mechanical equipment requires a lot of manufacturing resources, they are a far greater burden on capital expenditure, and much costlier to replace. In terms of capex, the only real benefit of rotary UPS’ (assuming it is a DRUPS system without any batteries) is that you don’t have to swap out the batteries every 4-10 years as you have to with statics.