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How to get the most out of your uninterruptible power supply

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When it comes to the efficiency of your UPS, it can be a bit of a battlefield, which is why a carefully thought out strategy is key to getting the most out of your system. Louis McGarry, sales and marketing director at Centiel UK Ltd, explains.

Over the last 25 years, we have seen significant advances in the efficiency of UPS systems across the industry. Moving from around 85% efficiency to the >97% range that we commonly see today, this has been a big step change in the march towards reducing the overall total cost of ownership (TCO) of power protection options.

Battles are decided by various factors including the number and quality of those involved in combat (you could say this is the manufacturer, the challenge, the client and, of course, the budget), the skill of the commanders (the experience of the engineers and system designers), the terrain (the type of facility) and the weapon of choice (the UPS itself).  

Historically, the focus to improve efficiency has been on the kit – the UPS equipment itself. However, in recent years, the margin in possible efficiency gains has become smaller and there are now only a few percentage differences between manufacturers.  

Even so, many manufacturers remain on this well-trodden path, continuing to try and make tiny improvements to the levels of efficiency of their kit.  But to make major gains in efficiency these days, UPS suppliers really need to look at different battle strategies for further major advances.  This can be achieved by working closely with those involved, presenting how different scenarios and configurations can generate long-term cost savings. In this way, using highly skilled system engineers to devise the best solution for the facility can pay the most dividends.

By this I mean a carefully planned approach is where the big savings on efficiency and therefore budget can be achieved now and in the future. Re-planning, re-sizing, right-sizing and introducing ‘pay as you grow’ configurations will be the best way to make the most improvements to overall efficiency and reduce the TCO of installations moving forwards.  

As UPS efficiencies differentiate less, manufacturers need to work more closely with the customer to scrutinise the design and plan of the UPS installation from the outset to see how savings can be made over time. Think of it as a 10-year strategic campaign. However efficient it is, an oversized UPS installed from day one, will cost more to buy, over the whole period it will cost more to run, more to maintain, need more batteries (which after say seven years will cost more to replace) etc. These costs soon mount up. A right-sized truly modular UPS will address all these issues and also offer the benefits of increased flexibility and reduced footprint.

When it comes to replacing legacy UPS with a true modular system the efficiency calculations are surprising. We recently replaced a legacy UPS in a financial institution. Two 12-year-old 400kVA monolithic blocks running at 85% efficiency at best, in an N+1 configuration was due for an upgrade.  The load had never reached its potential, so we reviewed the load profile over the years and replaced the system with one 300kW modular UPS delivering 240kW N+1.  The new configuration offered the same resilience but with a footprint which was five times smaller. 

The running costs for the legacy UPS including cooling were around £70k/year (calculated at 15p/kW hour). Now the client is looking at just £12k/year. The right-sized new modular UPS will pay for itself within 18-24 months and at that time it will still be within warranty. The ongoing savings over ten years will be significant. The smaller system will have lower maintenance costs, need less replacement parts and battery replacements will cost less too. It’s what we call a win-win-win.

This is a typical example where in the past, facilities have tended to install large standalone monolithic UPS blocks from day one. However, we live in changing times. The challenge with a large standalone UPS of say 500kW, is that it is always oversized unless the facility is at capacity. A modular UPS offers much more flexibility and therefore efficiency gains can be made.

When deploying a modular UPS, you have the ability to install the fully rated frame or empty carcass. This gives the option to add the required number of modules to suit the actual load and further UPS modules can be added only when needed.  All the individual modules are a UPS in their own right, all containing a rectifier, inverter, and static switch and all operating online in parallel with each other.  This offers much more flexibility.  

In this way, ‘a modular approach’ helps minimise the need for a large initial investment in a standalone solution: facilities can literally pay as they grow. It means facilities can scale as their load changes and they need more (or less) power protection.  

Maintenance is also far easier with a modular UPS solution. Compare a fault with a standalone UPS which needs to be switched off to fix on-site. The call out time for an engineer is at best usually four hours, then it could take them six to eight hours to fix the system. The paralleled UPS (N+1) will support the load but this is a risk as there is no backup during this time.   

On the other hand, if there is a problem with a true modular UPS, modules can be swapped in moments and repairs completed later offsite. There is no need to revert to external maintenance bypass and raw mains, the UPS can remain live while the module is changed over, as the other modules support the load.   

We have also provided first level response training to some of our clients so if they hold a spare module on-site, they can easily ‘hot swap’ themselves if necessary. This means modular UPS offer much greater levels of availability than standalone systems.  

Of course, when implementing a brand-new UPS, it’s more challenging to demonstrate cost savings than with replacement of a legacy UPS where there is an easy comparison. However, careful planning executed with military precision will certainly minimise running costs and maximise efficiency over time.  

I think the key to remember is that once a client has bought a UPS, they have to live with it.  We recently quoted for a new UPS to protect the load for a flight simulator. An 800kVA was specified but the load was only 300kW.  By an analysis of the actual load profile we estimated we could save the client around £70K upfront on CAPEX savings plus all the ongoing efficiency savings for running a right-sized system over ten years. It’s this joined-up thinking at the outset that ensures a flexible system which can be adapted to the changing requirements of the facility, maximising efficiency and minimising TCO whatever the future holds.

So, who will win the battle of the budgets? Clients who work with manufactures like Centiel where our mission is to provide a safe and secure environment which protects the critical load in the most efficient and therefore, cost-effective way possible.  

Yes, we have efficient kit, but by working together with our technical advisors who know how much energy a rack really burns, clients will be armed with the correct information and can make well-rounded decisions about their load profile from day one, and be ready to adjust for whatever may or may not happen in the future. The war on efficiency has now become less about making tiny improvements to the kit, but removing waste in the processes and deploying better battle strategies.  

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