What’s the best way to deploy UPS back up power?

Identifying where you have a need for uninterruptible power supplies is usually quite straight forward. Often what is more difficult to decide is how to deploy back up power from your UPS or UPS’s.

In simple terms the options are usually “Centralised” for one big UPS, or “Distributed” for multiple smaller UPS. While they may serve the same purpose, they fulfil it in different ways. Both solutions have distinct advantages and disadvantages, depending on the short- and long-term needs of an organisation.

Centralised UPS Strategy

Let’s imagine you have a 50 rack data centre with 5kW rack density. With the centralised UPS the entire data centre would be protected and backed up with one UPS. The UPS would directly supply the main building distribution board and everything supplied by the distribution board benefits from full UPS power protection and back up.

Advantages:

With a centralised strategy, the uninterruptible power supply is usually located in a dedicated UPS or plant room. This free’s up valuable white space in the data centre and keeps rack space free for servers, storage and network devices.

Whilst the alternative to a centralised strategy does remove the issue of a single point of failure, parallel UPS systems do make it possible to add N+1 redundancy to centralised UPS deployment.

Cost savings can also be made on maintenance, the cost of maintaining a single 300kVA UPS is considerably lower than maintaining 60 x 5kVA units and is a much simpler task for the IT or data centre manager to administrate.

Disadvantages:

With a centralised UPS system, the user has to decide on day one exactly how much power they “think” they might need in the future, but it’s difficult to know exactly how much power you will need and when you might need it. A centralised UPS strategy also requires a large amount of capital expenditure on day one.

Although the latest UPS technologies enable large UPS to still achieve quite high efficiencies at low loads, centralised UPS make it very difficult to right size the UPS and achieve a low PUE for the data centre.

Distributed UPS Strategy

With distributed UPS deployment, multiple smaller UPS are positioned in the server rack or adjacent to it. Each rack will have it’s own dedicated UPS or in some cases multiple UPS can be located in a single rack.

Advantages:

The up front costs of implementing a distributed UPS strategy are considerably lower than a centralised UPS system. As the UPS is dedicated to only what is in each rack, the cost of UPS back up can be spread over a number of months and years. Cost is only incurred when new racks are added and the demand for power in the comms room or data centre is scaled up.

Smaller UPS are also quick and easy to install; this allow for fast deployment and greater flexibility. It can also be argued that the greater the distance from the UPS to the server the greater the risk of power problems occurring. Locating the UPS in the same rack as the servers and network devices reduces the risk of wiring faults, noise interference and other issues.

Disadvantages:

Placing the UPS in the rack uses up valuable rack space, in high density rack applications the UPS system could take up as much as 10-12U.

Compared with a centralised uninterruptible power supply, management of multiple UPS in a distributed strategy can be a burden on the IT or data centre manager ad as we have already mentioned, the cost and time involved with maintenance of multiple systems is far higher.

Modular UPS systems

Modular UPS systems could be considered as the best of both worlds. Usually chassis based starting with as little as 10, 16 or 25kVA modular UPS offer the potential capacity of a single centralised UPS. Modular systems give the user the advantages of a single uninterruptible power supply, but with the same flexibility of a distributed strategy.

Modular systems allow the user to quickly and easily scale up the capacity of the UPS in line the demand for power and also provide N+1 redundancy. Being modular the cost of UPS deployment can be spread over longer periods and the highest efficiencies and lowest PUE can be achieved. Mean time to repair is very low in modular systems and maintenance costs are closer to that of a centralised uninterruptible power supply.

There is no right or wrong strategy when it comes to deploying UPS power. Which method is best suited to your application is dependent on where you are now and where you expect to be in the future. How you get there is where we come in.

Source UPS offer a free consultation and site survey to help you identify ways in which you could improve your existing power protection policy, so if you would like to discuss how we can help or woud like to book a site survey get in touch with a member of our team today.

Call: 01252 692559 or email: info@sourceups.co.uk