Planned maintenance visits (PMV) for UPS installations are essential to ensure the system is kept in optimum condition, so if the power fails, the UPS takes over to protect the critical load just as it is designed to do.  At CENTIEL, our engineers undertaking PMVs are highly trained and skilled.  Their aim is to protect the load and always provide best advice for the customer.

PMVs will see engineers complete a variety of visual checks to identify early warning signs to prevent any potential failures of important components. When AC/DC capacitors crack and leak or overheat it may already be too late.  When batteries crack or become swollen they have already caused damage and when fans have failed or seized your load is already at risk. Identifying early warning signs such as aging fans and capacitors and degrading batteries, allow remedial works to be actioned before your system fails.  The environment will also be assessed for temperature, airflow, dust and humidity levels, as these can all affect the correct working of the equipment.  Engineers will take note of all the important readings and record these in a field service report (FSR).

In addition, engineers can also test the resistance in each battery to build up a picture of resilience, forming trends of degradation.  This is an efficient way to identify and address weak or failing batteries before others become affected.  Some customers also require additional services as part of the PMVs and UPS maintenance plan.  These include items such as integrated system testing, black building testing and even load bank testing.  These additional services normally take place outside of hours and involve significant planning and preparation, with a co-ordinated approach to the entire infrastructure of the building.

The FSR produced by the engineer during the PMV holds essential information and is a valuable tool for the end-user/customer.  For facilities managers or end users, several areas require close attention.  Firstly, look at the recommendations in the ‘notes box’ on the FSR.  This sounds obvious, but it is surprising how many times this report is filed away without the end-user/customer taking heed of the information contained in this important box!  The notes section will include potential recommendations relating to remedials and replacements which contribute to protecting the load. Of course, your UPS service provider will communicate with you and follow up with quotations for remedial actions.  However, it is always good to have a complete understanding of why and when these remedial actions are required to allow for budget discussions and planning to take place.

Secondly, look at the dates for key critical life cycle components.  For example, AC capacitors will need replacing every 5-7 years to avoid failed components and potential fire hazards.   Whereas DC capacitors need replacing every ten years subject to manufacturers’ guidelines.  Considering if replacements need to be made in the near future can help maximise the life expectancy of your UPS system.  The key here is to take preventative maintenance actions not reactive ones.

Thirdly, consider the overall load.  This is illustrated in kVA/kW across all phases (a single phase will only show data for one load: L1.  A three phase holds data for L1 L2 and L3).  Has this increased since the last PMV?  Looking back over the past three years of reports will reveal a trend.  If the load has increased dramatically over time, consider why and if additional power protection is needed to support a growing load in the future?

The PMV can be seen as ‘just routine’ but far from it!  The information gathered and the resulting FSR is an important document and one that needs to be read, understood and acted upon in a proactive manner.  At CENTIEL our engineers are always trusted to provide the best advice and will be happy to discuss or show customers why they are making the recommendations on the report.  In addition, our service team work with customers’ individual needs to develop tailor made maintenance plans to ensure the critical load remains protected at all times.

For further information about preventative maintenance and our comprehensive UPS maintenance plans, please contact

Article originally featured in UK Power News Jan-Feb 2021.

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