Common Causes of UPS Failure

Common Causes of UPS Failure

When it comes to malfunctions of UPS, there is no shortage of potential culprits. In fact, UPS system failure is said to be the most common cause of unplanned data center outages, which could cost businesses a whopping $740,357. As the first line of defense in protecting your critical equipment, the last thing you want to do is unknowingly compromise part of your UPS system.

There are plenty of threats that might potentially cause your UPS to fail. Fortunately, many of them are preventable as long as you continue to maintain the system. Here are some of the most common issues that cause UPS failure.


The battery is the heart of any UPS system, hence it often becomes the leading culprit of UPS failure. Regardless of their age, UPS batteries need to be inspected semi-annually as part of a PM visit, which includes testing for impedance, performance assessment, and evaluation of potential weaknesses. The most common cause for UPS battery failure is incorrect temperature or temperature variance, which occurs when the battery temperature is outside the ideal range of 22-25ºC. Another common problem is overcharging and poor storage conditions, in which both have the potential to reduce your battery life expectancy by half.

The key to ensuring that your UPS can enjoy its maximum lifespan is by taking preventative measures. Regularly performing UPS Preventative Maintenance can help to increase battery longevity, detect abnormalities, and identify a failing battery before it causes a catastrophe.


A typical UPS contains a dozen or more different sizes of capacitors, which are responsible for smoothing out & filtering voltage fluctuations. Unfortunately, capacitors degrade over time just like batteries. However, you may be able to extend its life under favorable operating conditions – for instance, a typical capacitor might be expected to give seven years of usage time, but it might deliver up to 10 years of useful life when maintained correctly. Despite being a fairly simple component of the UPS, the capacitor is still an essential part to the UPS and thus needs to be regularly inspected. This is because a capacitor failure may trigger the UPS to switch to bypass mode, during which it cannot protect downstream loads and therefore shortening the UPS’s’ useful lives. Preventative maintenance of this often-overlooked element of UPS architecture may extend the value of the UPS system that protects your critical electronic system.


After batteries and capacitors, the next suspect for causing UPS failure are faulty smaller components, such as fans, contactors, sensors and circuit boards, with fans being the most likely cause. The electronic components inside a UPS switch at a very high frequency, thus creating a tremendous amount of heat, hence fans are used for cooling the UPS by moving a tremendous amount of air through the UPS. Generally, cooling fans have an operating life of 3 – 5 years, depending on the manufacturer. A faulty fan will lead to a rapid increase in temperature, which may result in the inverter or rectifier or charger to suddenly switch off. This problem may be caused by the dissipated grease inside the sealed bearings and the build-up of dust on the air intakes, which forces the fans to work harder in order to keep the air moving.

Some UPS manufacturers will build fan redundancy into the design of their uninterruptible power supplies, providing an indication of the fan failure without compromising the load due to inverter shut down. Moreover, most manufacturers will recommend a preventative replacement at between five and seven years. Although replacing fans that have not yet failed may seem wasteful, the cost of replacing one single fan is generally a lot cheaper than the associated labour expense of a UPS engineer along with the time required to complete the replacement.


There are several factors that may contribute to the failure of a UPS, which may cause a significant loss of time and money for your business. Instead of waiting for UPS failure and the resulting loss, it is better to conduct a routine check and replacement during maintenance visits. Protect your business from downtime from UPS failure by scheduling in a routine UPS inspection. At Northern Lights Data, we can provide you with a customised solution to meet your power management needs. With routine UPS prevention checks and maintenance, our team of UPS expert master electricians will inspect and monitor all systems, ensuring that your business is equipped to handle all challenges. Mitigate your downtime and losses and get in touch with New Zealand’s leading power management consultant today.

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