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How to Perform UPS Maintenance?

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Posted on June 2, 2020
September 26, 2020
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UPS (uninterrupted power supply) is essential when an emergency or unexpected outage occurs. It can offer uninterrupted power for network devices like storage devices, PCs, network switches, etc. To ensure the performance of such key features, UPS maintenance is vital. Read through this post to get UPS maintenance methods and tips in detail.

UPS Maintenance Methods

Listed below are four main aspects to check for UPS maintenance.

UPS Visual Inspection

Regular visual inspection is the most important step in UPS maintenance. One can perform some basic visual inspections to check the appearance of the device. For example, check if there is any accumulation of dust or dirt. Dust or dirt can block the ventilation holes of the device and cause it to overheat. If there is, clean the dust with dry cloth or other insulative cleaning tools. Besides, the inspection should include battery evaluation as well. Please note if there are signs of corrosion, leakage or swelling, as these signs indicate that the battery needs to be replaced.


In fact, comprehensive visual inspections also include internal component inspections. For example, check whether the AC input & output capacitors and DC filter capacitors are clean to make sure there are no signs of cracking or expansion. However, one may get exposed to dangerous currents when doing such inspections. Therefore, such inspections can only be performed by qualified personnel, such as electrical engineers, facility electricians, or third parties.

In addition to visual inspection, one should also listen whether there are unusual sounds and pay attention to abnormal smells. Either of them may indicate the existence of hardware problems.

Check UPS Temperature

Temperature check in UPS maintenance is another important task. Do make sure the temperature around the UPS is within the manufacturer's operating specifications. Checking the temperature of the UPS mainly uses thermal scanning, which uses a non-contact infrared thermometer to measure the surface temperature of the chassis. If the UPS is a fan-cooled one, one can use a thermometer to check the temperature of the air exiting the device.

Normally, if there are a large number of UPS devices to be checked, using a thermal imaging camera may be better since it can generate heat-based images, making it easy to locate thermal abnormalities in the UPS system.

Perform Regular Load and Load Bank Testing

Load testing and load bank testing are different procedures for UPS maintenance.

A load testing, or functional load testing, involves actually testing the UPS system at all functional points. This testing normally includes several types such as a steady-state load test, a harmonic analysis, a transient load test and a battery-rundown test.


  • A steady-state load test: A steady-state load test checks all input and output conditions at 0, 50, and 100 percent load and tests input & output voltage, input & output current, output frequency, input current balance, and output voltage regulation of the UPS system. This analysis can reveal if input currents match across all phases of a module, and it can help technicians determine if all modules equally share the load.

  • A harmonic analysis: A harmonic analysis enables technicians to observe the harmonic content at 0, 50, and 100 percent load, helping technicians to determine the effectiveness of the input and output filters. If there is a marked difference in phase currents drawn through a filter assembly, it means one or more capacitors have degraded.

  • A transient load test: A transient load test simulates the performance of a UPS with large, instantaneous swings in load. The UPS should accommodate full-load swings without distortion in output voltage or frequency.

  • A battery-rundown test: A battery system might be subject to failures that go undetected. A battery-rundown test enables one to observe temperature, voltage, and current under load conditions. Different voltages from battery to battery or battery set to battery set clearly indicate battery degradation. While conducting the discharge test, technicians should continue to check battery cell voltages. When the battery set provides approximately 80 percent or less of the rated capacity, it is time to consider a full battery replacement.

A load bank testing validates the correct operational performance of the system and its batteries. It can test the UPS system under a load in a simulative scenario rather than a live/real one. Load banks act as a battery tester and help to confirm operational performance without having to experience a real power outage.

Perform Alarm Verification and UPS Calibration

Alarm verification and UPS calibration are also important for UPS maintenance. Regularly verify that each UPS communicates correctly with the monitoring software. When verifying, please check the alarm log of each UPS to see if there are any signs indicating the abnormal behavior of the UPS. In addition to this, regularly ensure that the UPS has been properly calibrated. Even if the supported load is within the rated power range of the device, an incorrectly calibrated UPS will trigger an over-voltage alarm. This may also cause the device to display incorrect runtime data, which makes it more difficult to schedule the required maintenance.

UPS Maintenance Tips

In addition to the UPS maintenance methods mentioned above, there are many UPS maintenance tips one should pay attention to. Listed below are most common ones:


  • Safety first: If there is any uncertainty about some aspects of the UPS system or how to maintain or repair it, please call a professional.

  • Regular maintenance: Arrange regular maintenance time and record inspection results, which includes keeping a written record listing upcoming maintenance activities and whether/when past maintenance was performed.

  • Do not rely on UPS battery lifespan claims: In most cases, the life of the battery is three times shorter than the life declared by the manufacturer. Replace batteries in time.

  • Keep an eye on battery discharge status: Overly discharging a battery could affect its ability to recharge and lead to permanent damage. And if a battery isn't recharged within 24-48 hours it can impact its service life as well.

  • Put a spare battery on a separate rack: Maintain and charge extra batteries on a separate rack, which helps to change problematic batteries right away.

  • Purchase and use manufacturer-recommended battery: When purchasing a new UPS system, purchase and use the battery recommended by the UPS manufacturer to avoid dispute on after-sales UPS problems caused by improper purchase.

  • Deal with batteries carefully: Be careful of using chemicals or solvents around batteries. Besides, use proper protective gear when handling batteries.