We have an unplanned Eaton service visit today at 17:00 UTC-8. There was an odd behavior with the UPS the resulted in a utility feed side breaker trip, so we’re having them come inspect the equipment, download logs, etc. The result was that the affected UPS ran on battery for about 5 minutes while we investigated and reset the utility feed breaker; there was no impact to our facility operations.
This event is a good example of where batteries have an advantage over a flywheel system. Since the input breaker tripped, the UPS was relying on its DC supply (whether it’s batteries or flywheels) to support the protected load. A flywheel would not have lasted the 5 minutes it took us to check everything. Flywheels, of course, have a lower long term maintenance cost since batteries are consumable items that need to be replaced on a regular basis. The tradeoff is that flywheels do not have the run time endurance of batteries.
UPDATE: No anomalies were found in the UPS performance monitors.