Kohler Uninterruptible Power outlines the critical factors to consider when specifying a UPS for data centres, from scalability and battery technology to cooling and modular systems.
Kohler Uninterruptible Power outlines the critical factors to consider when specifying a UPS for data centres, from scalability and battery technology to cooling and modular systems.
Specifying an uninterruptible power supply (UPS) for a data centre application is one of the most critical parts of the design and planning process. Whether a stand-alone or co-located data centre, clients are reliant on its constant operation. Any downtime could be catastrophic to organisations both financially and reputationally.
Data centres are part of the mission-critical infrastructure industry. So design teams must work closely with UPS specialists to get this right from the outset. And ‘getting it right’ is about more than ‘Day One’ operation. It’s about scalability, battery reliability, resilience and redundancy in the long term.
Many data centre designers and operators work to the Uptime Institute’s Tier Certification. This is an industry-wide standard for the whole process, giving investors, operators and end-clients confidence in the design, build, operation and ongoing maintenance of the data centre. Uptime’s Tier Certification certifies a site to one of four levels:
Tier 1: Basic Capacity
Tier 2: Redundant Capacity Components
Tier 3: Concurrently Maintainable
Tier 4: Fault Tolerant
Sizing a UPS for your data centre
Every data centre is different – and every UPS solution needs to be designed accordingly. Here are the most important things to consider:
- The load
The load in your data centre will define every other decision you make. The first step in sizing a UPS for your design is to know exactly what the load will be at day one and in the future. This includes the IT load, which is the servers and other equipment in the data centre – but you should also include the mechanical load for the wider operation of the site. The higher the load, the higher power you will need from your UPS.
You also need to consider that if your data centre will be supporting AI applications now or in the future, you will need a higher rack density. Your load will be significantly higher, so make sure you build in both the IT load and the required cooling into your calculations – somewhere between 36kW and 50kW [AE1] is the new normal. AI applications are driving rack density and power requirements to new heights.
- Battery technology
UPS systems use battery power. Traditionally, those batteries have been VRLA – Valve Regulated Lead Acid batteries. Lithium batteries have overtaken VRLA in many cases because they have a longer design lifespan – up to 20 years in some cases – and they take up less space in your plant room. Historically, lithium batteries have been more expensive, but manufacturing processes and their use in many other technologies have seen the price come down.
More recently, Nickel-Zinc batteries have demonstrated a clear value for UPS technology. They can deliver higher power density, have a smaller footprint, reduce installation time, and are more sustainable to produce. And, because these batteries are already pre-installed in battery cabinets, the system can be easily assembled and tested off-site, proving reliability and improving speed of installation.
Battery technology is always advancing. New technologies include flow batteries, graphene batteries and sodium-ion batteries. A UPS specialist will work with data centre designers to understand their needs and then suggest the safest and most reliable battery choice to meet the requirements.
Alex Emms, Technical Director at Kohler Uninterruptible Power says, “We usually advise data centres to choose separate batteries rather than a common battery. Theoretically, you only need enough UPS battery runtime to carry the critical load until such time as the generators start and the load is transferred to them. This is typically just 10-20 seconds.
“That said, the battery runtime will vary depending on the end-user risk tolerance and the resiliency of the IT applications that are being supported by the UPS. For example, hyperscale data centres are being designed with 1-2 minutes of battery runtime. Cloud and colocation data centres are typically designed with 5 minutes of battery runtime. And in the financial industry, you will typically see 10-15 minutes of battery runtime.
“The amount of UPS battery runtime is a customer business decision. Obviously, the more battery runtime you incorporate into your design, the higher the capital cost and the higher the annual maintenance cost, but your clear return on investment is the continuous smooth running of your site.”
- Cooling factors
Cooling is essential to data centre operation. It creates the optimum environment for the technology in the data centre and needs to be maintained during a power outage or any other emergency. It should be factored into your load calculations.
Cooling is also important for UPS batteries, so siting and battery care need to be part of the UPS design. VRLA batteries work best at a stable temperature of 20°. Above 20°, battery life begins to degrade. Once the temperature exceeds 30°, battery lifespan can be reduced by up to 50%. Excessive heat also has a detrimental effect on Li-Ion battery chemistry, and also requires a controlled environment at 25° to operate at their best.
- Modular UPS systems
Data centre designers are increasingly choosing modular UPS. There are several reasons for this:
Efficiency: Modern UPS units are designed to be as energy efficient as possible. The Kohler MF series delivers 97.4% energy efficiency in VFI mode, giving data centres exceptional value for money.
Scalability: You must consider the future operation of your data centre. A modular UPS gives you the ability to increase your UPS capacity as the IT and mechanical load of your site increases.
Smaller footprint: Modular units need less space to house them, and they are easy to swap out for maintenance or service.
Redundancy: A modular system can easily be designed with redundancy by simply adding modules. This ensures that whatever happens, your operation can continue to run. The modular approach offers N+1 or greater redundancy.
Cost control: Your total cost of ownership is likely to be lower with a modular UPS as you can control energy use as your load changes. It’s also cheaper to replace a single module than an entire monolith UPS system.
- Data centre growth
Future scalability and growth should be part of your UPS sizing criteria.
A report from the Uptime Institute in 2021 forecasting data centre trends in 2025 stated:
“Power infrastructure requirements in data centres will be shaped by several factors in the coming years. For many, power architectures will be driven by pressure to lower capex without additional risk, while for others, regulatory concerns or changing customer requirements will play an increasingly prominent role. More operators will pursue higher levels of efficiency, adaptable resilience, and integrated automation. The use of new battery technologies (and of renewable energy sources) will spread, particularly for data centres supporting very large critical loads — of which there will be many more.” Uninterruptible power: Adoption trends to 2025, UI Intelligence Report 47, April 2021.
This applies to data centre design today. Balancing capital expenditure and operational expenditure against client demand, technological resilience and continuous operation remains a challenge.
Designing a power-efficient, cost-effective and easily maintainable and scalable UPS solution enables data centre operators to make strategic growth plans with confidence.
The KOHLER MF modular UPS series
Designed specifically for use in high-powered, co-location and hyper-scale data centres, the modular MF series from Kohler Uninterruptible Power is the next generation of UPS solutions. Our advanced, industry-leading technology delivers a highly efficient range of products. The MF series is resilient, flexible and scalable and delivers a lower total cost of ownership alongside proven reliability.
- Online double conversion UPS
- DPA 250 kW to 1,500 kW – parallelable to 6,000 kW
- DPA-CSB 1,500 kW to 2,000 kW – parallelable to 4,500 kW
- Slide-in vertical modules
- Single feed and dual feed options.
KUP is an unrivalled single source for complete power protection, working closely with data centre engineers and designers to supply and maintain modular UPS solutions to data centres across the UK, Ireland and Singapore. Contact KUP today at [email protected] or call on 0800 731 3269 to find out more.
KUP will also be running a series of events on battery solutions for data centre UPSs starting this September. Following the success of their recent event with nickel-zinc battery partners ZincFive, KUP will be running another live hands-on Q&A session with ZincFive at the KUP offices in Hook on 20 September. Engineers can find out more on the free day here.
And on October 16, KUP will be holding a free CPD webinar on battery innovations and technologies, looking at how to compare and evaluate each option to help data centre engineers chose the right solution for them. You can register for your free space here.
