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Uninterruptible Power Supply Problems [and Solutions]


Whether you have older or newer equipment, many UPS failure problems could be avoided with some preventive measures. There are several actions you can take to run your business smoothly during power outages and not lose your precious customer data or existing customers entirely.

UPS (or Uninterruptible Power Supply) system consists of many components that could fail at any time, this why preventive maintenance checkups are required. Following are essential components of UPS along with their maintenance and replacement schedule:

Component Maintenance Replacement
Batteries Check twice a year Lead-acid batteries last 3-5 years, lithium-ion – 4-10 years (all batteries should be replaced when becoming bad or unusable)
Capacitors Check annually 5-7 years (replacing every 5 years is recommended)
Cooling fans Check annually About every 10 years (or when needed)

UPS is a critical power system during outages and if your critical load depends on it, you don’t want any mistakes. Now, let us guide you through UPS power supply problems and possible solutions to them:

  1. UPS troubleshooting
  2. Causes of UPS failure
  3. UPS components that can fail
  4. UPS maintenance companies

UPS troubleshooting

What to do if UPS is not behaving “properly” or completely stops working? How would you even know if you will have power if a blackout occurs? Here are some tips to help you out.

  • Make sure your UPS is plugged in. If you have trouble turning it “ON”, check if it is connected to an electricity source and that the breakers are not tripped.
  • Make sure you turned UPS “ON”. Your unit needs to be “ON” in order to function. If you just installed your brand new UPS system, you will need to press an “ON” button to get it to work. Plugging UPS into the wall socket is not enough! It will not start working until you press an “ON” button, regardless of the lit LCD screen.
  • Check the fuse of your UPS. If you did everything right and checked all the wiring but your UPS is still not turning “ON”, it may have a problem with a blown fuse. Get a professional to check and replace it.
  • Check the wiring. When utility power is available, your UPS unit should not use batteries! If you noticed that it uses batteries when it shouldn’t, make sure UPS is being supplied with power and check circuit breakers as well. If the unit is “ON” and everything is fine with your electricity supply, contact the manufacturer’s technical support.
  • Check batteries. UPS should be able to provide power backup if needed, right? Even though the “change battery” status did not come up yet, your batteries may be worn out from frequent use. Use the “self-test” function of your UPS on a fully charged battery to make sure it works. If the test fails, the “replace battery” light will be displayed.
  • Size and balance your load properly. Make sure your UPS is properly sized for your load and can handle it. If you have a three-phased UPS system, then load balancing is very crucial in order to avoid THD (or Total Harmonic Distortion) issues. Under-usage will create energy waste.
  • Connect only the most important equipment. If you noticed that there are lots of equipment connected to your UPS and not all of it is crucial during a power blackout, unplug it. This will lengthen the time UPS can supply power to your critical equipment and computers.
  • Get professional advice and maintenance services. Industrial size UPS requires careful management. If your Uninterruptible Power Supply system is rather huge, you need a professional to check it on a regular basis. Especially if you have a problem with your wiring, this is not a DIY project.

Causes of UPS failure

If you cannot afford downtime, you need to be aware of what causes UPS to fail. Here is a quick summary of my research on this subject:

  • Heat. Batteries do not like to be stored or used in high-temperature environments. The cooler the environment, the longer the lifespan of a battery.  Select one room for your UPS where you will NOT turn A/C off in order to save money! Keeping temperature around 68-77°F (or 20-25°C) is acceptable.
  • Dust. UPS systems have a low tolerance to dust and should be kept in the dust-free area that is being cleaned regularly. Dust and airborne debris can clog the fans of UPS and cause overheating. In the best scenario, overheating will cause power failure when needed, in the worst one – FIRE!
  • Humidity. The humidity of the room where your UPS is located should be checked regularly as it may impact the performance of your equipment. Air conditioning generally gets rid of this problem, especially in the summertime.
  • Long storage time. Batteries will go “dead” if you do not charge them for a long period of time. So if your UPS has been on the shelf for a while, you may end up replacing it right away.
  • Loose connections. If you have some kind of machinery running close to the location of your UPS, this may result in loose connections inside the unit due to vibrations. It can be checked by a professional once a year.
  • Technology. Lead-acid batteries, which are commonly used in UPS systems, can degrade very quickly in comparison to lithium-ion batteries, which can last longer, as well as charge faster. Tesla Powerwall is a good example of this new technology and APC Smart-UPS is using lithium-ion batteries that they claim lasts 2x longer than lead-acid.
  • Over-cycling batteries. Most batteries could last for up to 5 years if not being heavily used (many recharge cycles). In about 3 years, batteries lose about 20% of the initial capacity and if used heavily or in improper temperature conditions, their lifespan will go down even further.
  • Internal components wear. This is a big one and is something that is really hard to detect if you are not a professional. Many components of your UPS need to function together in order to provide you a complete power failure coverage and if one of them goes bad, the whole system stops working.
APC Smart-UPS Lithium-ion Short-Depth UPS | APC by Schneider Electric

UPS components that can fail

  • Batteries. At the “heart” of your UPS system are always batteries! They should be inspected twice a year by a professional. If they end up being too weak during a power outage, you may end up with less backup time than expected. It generally needs to be replaced every 3-5 years (double that time for lithium-ion).
  • Capacitors (or Caps). Capacitors are responsible for smoothing and filtering voltage fluctuations. UPS systems in general, use several capacitors at the same time, and their lifespan is around 5-7 years. Capacitor failure will leave your sensitive equipment unprotected from spikes and other electrical fluctuations this is why annual inspection is recommended.
  • Cooling fans. Decreased ventilation to your UPS unit can cause component overheating. A common reason for fan failure is mechanical problems and worn-out bearings. In a normal working environment, they could run up to 10 years. Should be checked once a year.

UPS maintenance companies

How to make sure your UPS will work when it needs to? It is suggested to have your UPS inspected by a professional twice a year in order to avoid failure problems.

An uninterrupted power supply (or UPS for short) is a very delicate machine that many things can go wrong with. This is why quite a few companies created services in order to give you equipment proper service and care.

Following companies provide maintenance plans for your UPS:

  • Unified Power. Offers customizable preventive maintenance service. Website >>
  • Quality Power Solution. It also includes emergency and preventative maintenance services. Website >>
  • Global Power Supply (GPS). Provides routine maintenance services and scheduled inspections. Website >>

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