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By Aaron Oddy, Sales Engineer at CENTIEL UK

A UPS protects the critical load within all types of facilities.  The highest quality, true modular UPS systems will increase availability and resilience whilst removing single points of failure.  However, simply installing the very best UPS on the market is not enough to completely mitigate the risk to the critical load.  We also need to look outside the UPS box to ensure the surrounding infrastructure also avoids single points of failure.

In a new build, this can be relatively straight forward, however, we may be installing the UPS into an existing building or an empty room with no infrastructure.  The ideal scenario is to create a separate room for the switch gear and batteries.  This minimises air conditioning costs as the UPS can run at a higher temperature than VRLA batteries, which need to be kept at around 20-22 degrees C to optimise their design life.

We work with clients to establish information about the load in order to understand their needs and provide the right configuration for the UPS and associated infrastructure.  Modular UPS systems can offer the flexibility, availability and scalability to suit most facilities.  Therefore, we need to understand what the load is supporting, how critical it is and what the load consumption will be, so we can provide the optimal solution and ensure it can be right sized from the outset.  Oversized UPS systems cost more to buy, install and run so getting this right from day one reduces Total Cost of Ownership (TCO) for the end user.

We also need to understand the required resilience of the system.  Will an N+1, N+N or 2N+1 configuration be needed?  Also, the autonomy or run time of the batteries needs to be considered.  This will depend on how long it takes to undertake a graceful shut down to protect servers or to switch over to a generator.

Using an N+N UPS configuration is often a good solution for critical facilities as it introduces duplication and redundancy of systems.  Risk can further be mitigated by using an A & B configuration, meaning two separate power supply paths are used, and there is no single point of failure from the power source to the UPS to the load.  If both power supplies come from a single source, loss of mains will cause both UPS systems to run on DC, until mains are restored, or a secondary power supply is provided i.e., a generator.

This extra level of resilience through duplication also needs to be considered for the outputs of the UPS too.  For an A & B system, two separate distribution boards will enable one side of the UPS to be isolated for maintenance while the other ensures the load remains fully protected.

For new build installations we can advise on the best configuration of the UPS and associated infrastructure.  For legacy installations perhaps which were installed 10-15 years ago, now ready for lifecycle replacement, the challenges are slightly different as we are often working with ‘what we’ve got’.   Here, we need to carefully assess the current situation and see what needs to be changed to mitigate risk to the load during the installation and in the future.

We often find that even though the infrastructure, including the UPS systems have been designed with separate A & B feeds, certain loads may not always have the capability of being dual fed. This introduces single points of failure and puts this critical load at risk. To remove this risk, it is essential that they are fed via fast-acting static transfer switches taking independent supplies from each UPS system.   Similarly, a centralised output distribution board can also add a single point of failure into your overall infrastructure, in some cases this is the only option. Be aware, that in this scenario, if the UPS needs to be isolated or removed, the shared output board remains live and cannot be maintained unless the load is shutdown.

To fully remove risk to the load, everything needs to be duplicated, the mains input supply, the output distribution, and everything associated to the UPS system including the batteries. Removing all the single points of failure within the surrounding infrastructure is just as important as within the UPS set up itself.

Recently we were presented with a replacement situation that had a centralised infrastructure and no means of bypassing the UPS system.  This meant that there was no way of replacing equipment without shutting everything down, which was not an option for the client. Fortunately, we were able to create a safe workaround as the load was fed by dual output distribution.

We partnered with other specialists to supply an external energy farm; essentially a mobile solution that can include a UPS and generator which can be deployed to any site. This enables us to provide secure power to the load during the decommissioning of the existing UPS system through to the commissioning of the new. This ensures the load remains supported for the duration of the works.

Working closely with the client and other contractors we scheduled and agreed a timetable of works so everyone on site was prepared for the switch over. Mitigating any risk before the next element of works took place was essential.  Here, communication was a key element of a successful installation to ensure risks are identified and timescales established so everyone is comfortable with their area of responsibility.

To remove any risk during future works we installed an external bypass which means, there will be no need to shut down and switch to a temporary power protection for upgrades or any remedial works to the UPS.

For any legacy UPS systems that are being considered for replacement, a comprehensive site survey identifies issues early and enables solutions to be put in place to overcome any challenges which are presented.  A facility may appear to have the highest level of resilience but often it is not quite as simple as that!  Additional work may be required to ensure the load remains protected during the new installation.  However, a thorough site survey, close collaboration with clients and thinking outside the UPS box, means we can create a future proofed system which removes single points of failure not only from the UPS but associated infrastructure too, protecting the critical load.

At Centiel, our sales engineers work as trusted advisors to clients and consultants throughout the UK and are always happy to discuss particular site challenges and help overcome issues to ensure critical power remains protected at all times.

Originally featured in Electrical Review Magazine March 2022.

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