Ryan Jones, business development manager, Riello UPS, offers some top tips to ensure your uninterruptible power supplies perform at their best and identifies the key components you need to keep a watchful eye on.

Whether it’s a small plug and play unit protecting a home gaming setup or a multi megawatt system backing up a server room, a UPS is a complex device in its own right.

And just like any other piece of sophisticated equipment, how well you look after it will have a significant impact on reliability, performance, and eventual lifespan.

This week, we’ll focus on two of the key elements that make up a UPS but are the most prone to failure. While we’ll also highlight the importance of proactive maintenance and explore what a typical service visit should cover.

Caring for capacitors

A typical UPS contains dozens of capacitors ranging in size from a mini drinks can to a tube of Pringles. These various capacitors (AC input, AC output, DC) work together to enhance overall power quality by smoothing, filtering, and storing energy.

But they age over time. The electrolyte, paper, and aluminium foil inside degrade physically and chemically, impacting performance. In general, capacitor lifespan shortens due to a combination of overuse, excess current, or excess heat, which evaporates the solution inside and builds up unsafe pressure.

There are several signs a capacitor is about to fail, such as deformation caused by excess heat, a fluid leak, protrusion on the valve cap (evidence of stress), or scorched wires.

If a single capacitor fails, the rest of the set must pick up the slack. This places them under greater stress and downgrades the UPS’s ability to filter power, increasing the likelihood of problems with harmonics.

In favourable operating conditions a capacitor can have a service life of up to 10 years. But while there’s no standard age where a capacitor will fail, best practice recommends replacing them between years 4-8.

Basics about UPS batteries

Did you know that the vast majority of UPS failures (around 80%) are traced to issues with the batteries?

Single-phase and smaller UPSs are typically installed with five year design life batteries, while larger three-phase UPS batteries will come with a 10 year design life.

Assuming perfect operating conditions, those batteries should last for five or ten years respectively. But of course, there’s no such thing as a ‘perfect’ environment.

EUROBAT (Association of European Automotive and Industrial Battery Manufacturers) guidelines stipulate batteries reach the end of service life when capacity falls below 80% of the original. So with 5 year batteries it is best practice to proactively replace in service year three or four. For 10 year batteries it is year seven or eight. This provides a safe margin to mitigate any drop in performance.

Many factors impact the lifespan of your UPS batteries, including the frequency and depth of discharge, or the operating voltage. But by far the biggest cause of premature battery failure is high ambient temperature. Most UPS batteries have a rated capacity based on operating temperatures of 20-25oC. For every 10oC increase, service life halves.

TLC for your UPS

Just as many of you will have an annual service on your car or boiler to ensure it is in tip-top shape, the same principle applies to your UPS too.

Indeed, most UPS maintenance contracts will include at least one planned PMV (preventive maintenance visit) every year. But even if you don’t have an ongoing plan, an ad-hoc service is highly recommended.

A PMV provides the opportunity to identify potential issues and fix them before they have chance to develop into more serious faults.

So what does a PMV cover?

  • Visual inspection and physical tests: at the start of every service visit, the engineer will thoroughly clean any dust or debris in the unit, then look at all the key parts and components, including the batteries, for any obvious signs of deterioration. They’ll check and, if necessary, tighten all the electrical connections too. Most UPS maintenance providers use advanced thermal imaging cameras here, which can detect potential hotspots better than even the most experienced engineer.
  • Mechanical and functional tests: the engineer will proceed to download the UPS’s historical alarm and performance logs, before carrying out several tests to see how the UPS runs in various operating modes.
  • Firmware updates: PMVs provide the perfect opportunity to ensure your UPS has the latest software installed, which can have a big impact on performance and efficiency.
  • Service report: the final port of call sees the engineer complete the maintenance register, provide a full report of any faults, and highlight any recommended remedial actions i.e. any components that are approaching their end of service life and due for replacement.