Why do I Need UPS Maintenance?

A blog about UPS Maintenance and what a UPS System is used for.

Why UPS Maintenance?

Uninterruptible Power Supply (UPS) units are often the first line of defence to protect your critical load equipment. They constantly take the incoming mains power complete with spikes and surges and perfectly regulate a clean stable power output.

Careful planning and significant investment goes into UPS as part of a power protection strategy and even business continuity planning. When your UPS is working correctly, you will forget it is there. But should you?

Once a UPS is installed and commissioned it can sometimes be left until it next alarms before giving it a second thought. With UPS becoming a commodity item and initial product price decreasing some manufacturers now start to charge a premium for ongoing service and “maintenance”. But what exactly is entailed in that “maintenance”? That’s why some of the most prevalent questions I have had from users over the years is, what should I include in my UPS service and maintenance agreement? Do I even need one?

What is a UPS?

A UPS is an electrical device designed around sophisticated electronics enclosed in a metal or plastic box. With exception of the cooling fan it has no mechanical moving parts like a standby diesel generator, so what could possibly require maintenance? In actual fact very little and the term “maintenance” for works performed during a visit to a UPS is probably now used incorrectly. There is very little if any “maintenance” that can even be performed on a visit from an engineer to a UPS unless he is specifically replacing aged parts. So, why do I need an agreement or contract?

Although the cooling fans are probably the only mechanical moving parts on a UPS (They can be cleaned or in some case greased). The remainder of the unit is designed around electronic devices that switch fantastic amounts of electrical power tens of thousands of times a second. This is all driven by algorithms written in firmware controlled by Digital Signal Proccesors (DSP). These complicated electronic switches have a design life and will eventually wear out and fail when used for long enough in the wrong conditions or environment. When they do fail, they will most likely go short circuit, which will result in one of the most loudest bangs you will ever hear accompanied by some smoke which may set off any fire suppression present. What follows (after the fire brigade) is a long investigation into what happened from various specialists, consultants, engineers and worried managers.

UPS operating conditions

These devices (which are basically complicated switches) are designed to run for up to tweny years, but only under the environmental conditions and loading limits they were designed and manufactured for.

Therefore a vast majority of the time utilised on a UPS engineers “service” visit as part of a service agreement or contract involves checks. Basically checks that the UPS is operating in the correct environment under the correct load and isn’t being damaged by any external factors. Some of these “checks” can and are completed daily by the user. The temperature of the UPS room, safe output loading of the UPS, even for the adventurous the use of the inbuilt battery testing function while following the basics of keeping the UPS area free from excessive dust, moisture, clutter or cups of tea (Yes all too often UPS units can make handy shelves)!

However, just as important as these basic routine checks are the ones that must be completed by an experienced UPS engineer.

The technical stuff

Upon learning the correct switching procedure and safely shutting down the UPS, whilst maintaining critical load through the bypass line, the UPS can then undergo a detailed visual check of all components, connections can be checked and tightened if necessary, signs of corrosion can be noted and excess dust deposits can be removed should the environment be harsh. The DC & AC capacitors, IGBT devices and batteries should be visually inspected for signs of budging, leakage or overheating – all are signs that the components may be failing (or approaching that Bang scenario).

If the visuals check out, the UPS engineer can then restart the UPS and take on-load readings. The DC side of the UPS can be measured for AC ripple of both voltage and current (High ripple on the DC could indicate worn capacitors or aged batteries). The measurement of the output AC waveform can highlight aged AC filter capacitors. Analysing the input power to the UPS can also highlight mains issues such as high harmonics, poor power factor or even just high voltage – for short periods of time the UPS is designed to filter these mains issues from the critical load, but permanent running with higher than nominal input voltage or high harmonic content will cause the premature aging of components within the UPS. If the external factors cannot be rectified, this should be noted and recommended action be taken in due course.

Whilst a user will be able to clearly see any current alarms on the UPS, usually it is only the UPS engineer that is able to download and analyse detailed history logs of conditions the UPS has been subjected to and how it has behaved since installation (or the last service visit). This is all vital information for predicting how long components such as capacitors and batteries will have a useful life for.

Finally, firmware, depending on the age cycle of your UPS it may have a newly updated version of firmware for control of the sophisticated electronics. Only an experienced and trained UPS engineer should attempt this (and if anything doesn’t go to plan, you want him there anyway!). New firmware is vital to prevent you experiencing unexpected events, which unfortunately other users of the same product may have already reported. An upgrade protects you so well worth insisting upon, especially if the manufacturer recommends it.

Sophisticated job tracking

With our sophisticated job management software, we are able to ensure you, the customer gets a timely report as soon as the service has been undertaken. Our engineers have access to your system information, parts schedule and potential likely issues based upon the history of the UPS. This means we are always prepared before we arrive on site and are able to ensure your system is carefully looked after for the duration of it’s life span.

Our findings

Finally, all of the findings during a service visit should be communicated to you in a swift, clear and transparent method. You can then make decisions or ask for assistance or recommendations in actioning.

So, after reading my thoughts on the above, in answer to our questions, what should I include in my UPS service and maintenance agreement? You should ensure that as a minimum all elements discussed above are completed during the visit, then communicated clearly to you along with any potential risks and recommended actions are followed up. Do I even need one? If the UPS engineer is just going to turn up check for green lights then ask you to sign a piece of paper, Id probably just save your money and wait for the Bang.


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