UPS Load-bank testing
During load-bank testing on newly installed UPS system batteries defective cells and poorly connected links were highlighted using the thermal imaging camera. Battery links will display abnormal patterns very quickly while load is applied while the cells will increase in temperature more slowly and time will be needed to allow the temperature to soak through the casing of the batteries.
Once installed the UPS batteries were connected to a load-bank to allow autonomy tests and functional testing to be completed. During this short test the batteries were loaded to 100% UPS capacity and were constantly scanned with the thermal camera. As the duration of the test is so short it is necessary to use a minimum of two cameras-especially with larger systems. With the load disconnected and battery autonomy reached we continued to scan the batteries for evidence of defective cells. Connections at the battery isolators were also imaged during the load-bank run.
During the battery load-bank runs we identified any cells that had elevated temperature and links that were displaying uneven temperatures along their length. Manufacturers specifications were used to determine which cells fell outside the normal operating temperatures while loaded. A full report of our findings was issued for inclusion in the installers O & M manual and Integrated Systems Testing results.
Following the load-bank runs and when the defective links and cells had cooled they were replaced.
The nature of UPS systems means that the batteries are not loaded until a power failure occurs. This is when they are called on to support the critical supplies. Defective links and cells will lead to shorter autonomy times and in very severe cases defective links can cause the entire system to cascade into complete failure. Thermal imaging of batteries under load will easily and quickly identify those links and cells that have or are likely to fail. The tests are carried out under controlled conditions and in almost all situations the remedial works are easily completed by the installers.