Maintenance: Prevention is Better than Cure

5 Jun, 2019 | Industry Insights

If you owned a Mercedes would you take it to your local Halfords for a service? Probably not. You would more likely, use the nearest specialist garage, experienced and competent in fixing your particular vehicle. As well as understanding the make and model of your car and its history, they are more likely to have spare parts already in stock and if not, be able to source them quickly.

Yet, there is an endemic industry problem when it comes to UPS maintenance. Contracts for the maintenance of a UPS designed to protect a critical load frequently seem to be covered by the ‘cheapest’ option which involves minimum maintenance, often carried out by engineers who are not specialists in that particular manufacturer’s model of UPS.

We were recently called in to advise a local hospital where the operating theatre needed to undertake £100K worth of operations per day. We reviewed the maintenance contract and found that a ‘cost-effective’ solution had been agreed, and the providers were not specialists in the equipment being used. A few days later, when an emergency did occur, the attending engineer didn’t have the spare parts required to get the system back on-line and we were asked if we could assist. We deployed one of our engineers straightaway to investigate and rectify the situation (typically it always seems to happen s in the middle of the night!) The morale of this short story is that cheapest is most certainly not best, it may appear to reduce the upfront cost of a maintenance contract but at what financial cost long term, or worse patients’ lives potentially put at risk?

Understandably, in a large facility with various UPS configurations from different manufacturers, it may not be possible to find one provider who is familiar with all the necessary service updates on all of the UPS types. Best practice would be to employ a company that specialises in the UPS systems installed and one that can provide spare parts. With a multi-unit, multi-type, site then an “umbrella” contract with a single point of contact, and responsibility, can be employed who will back-to-back the specialisms to those expert providers.

The good news is that many issues can be prevented through correct routine maintenance. If one fan is not working the UPS can still function properly but if two fail, the system will in all probability overheat. If this occurs the UPS will transfer to static bypass mode. Bypass meaning the load will not be protected during a power cut. Regular checks of fans will prevent such challenges.

Capacitors, on the other hand, tend to fail suddenly and sometimes spectacularly. They can catch fire and even explode, damaging other components and presenting a serious hazard to staff. Often, there are no warning signs. However, a competent maintenance provider will advise on the appropriate date to replace capacitors as their life span tends to be based on the length of time they are in operation, rather than on their level of use.

Batteries also need checking regularly, unlike capacitors they fail gradually. Slow degradation of one battery can then age others in the same string and should be replaced. A maintenance engineer should perform regular battery tests, e.g. simulating mains failure – but in a safe way – without compromise to the load. Batteries should discharge evenly and if not, the engineer should undertake an impedance test on each battery to isolate the weak link and arrange for it to be replaced.


We talk a lot about minimising downtime in this industry and how UPS systems are now highly sophisticated with the leading manufacturer’s systems offering very high levels of availability. However, without regular maintenance by specialists, your UPS will not continue to operate optimally leaving your critical load vulnerable.


In this article, we have touched on just a few points that need regular review. Our own network of factory trained CENTIEL engineers visiting a facility have a factory designed maintenance program which checks the condition of all essential components. Clients are made aware of the need for any replacements to ensure the continued running of the UPS. Preventive maintenance is key to maintaining the availability of the system over time.

Article origonally featured in UK Power News May/June 2019

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