Your Field Service Report Part 4: Thermal Image Scanning

Our fourth and final entry in our series on understanding field service reports looks at deciphering the results of thermal image scanning. The thermal image scan is important enough that QPS believes that every preventative maintenance check should have one performed. Thermal image scanning is one of the most reliable ways to predict impending UPS component failure, and if components, or the entire UPS, needs to be replaced.

Thermal imaging isn’t done by taking pictures with a traditional camera. Thermal image scanners detect an object’s infrared radiation and create an image based on that information. The higher an object’s temperature, the more infrared radiation it gives off.

There are several components of a UPS that technicians are paying close attention to when they perform a thermal image scan. These components include:

• Printed Circuit Boards (or PCBs)
• Transformers
• Capacitors
• Insulated Gate Bipolar Transistor (IGBT)
• Silicone Control Rectifiers (SCRs)- This component transforms AC to DC power
• Batteries
• Fans

Technicians are typically looking for a temperature range on these components that fall outside of manufacturers defined tolerances. The hotter the temperature is above that tolerance, the greater the potential issue. As a general rule, excessive heat is a strong indicator of failure.

Sometimes thermal image scanning can be difficult based on the design of the UPS, or due to how the UPS is positioned in a particular space. Silicone control rectifiers, IGBT, and sometimes transformers can be hidden behind boards due to design requirements of the UPS unit. If these components are hard to get to or hidden, the UPS might have to be shut down and a thermal scan performed while still hot in order to get proper thermal image results.

Another potential difficulty is that the UPS unit may have transformers positioned in the back of the unit, so that they are only accessible by opening the rear of the unit. Depending on the set-up of the unit in a room, this may prove to more difficult than normal and may not be feasible.

Once a component is shown to be hotter than is acceptable, the most important next step is for the technician to communicate with the client based on the observed results. Your field service report should show photos of the scans, pinpointing the areas of concern on each component where necessary. Depending on results, one of several fixes might be recommended including:

• Continued monitoring on the unit
• Proactive replacement of overheated components
• Possible total unit replacement, depending on number and temperature of overheated components , and depending on overall age of the equipment

The environment the UPS unit is in should also be carefully taken into account. The following questions should be considered:

• Has the environment had equipment added recently, increasing the ambient room temperature?
• Is the UPS properly situated in an environment it is suited for?
• Are the fans and ventilation to the UPS system clear and properly functioning? 
• Does the room  have enough room for growth and expansion, including increased heat output?

If you are concerned that your UPS may have overheated components, we can help. Contact QPS to discuss if a thermal image scan of your equipment makes sense for you, and let us help you interpret you results of your field service report.