Maintenance
If you are responsible for the secure storage of electronic data then you know full well just how important an uninterrupted power supply is. The national grid in the UK is one of the most stable electricity networks in the entire world, yet even this sometimes suffers hiccups. As the majority of the power is carried over ground, the transmission media will always be vulnerable to unforeseeable, but no less possible, accidents. This is why it is important to have UPS batteries to offer some kind of back up regime to your usual power source.
Along with accidents to the power lines themselves there is also the chance that malfunctions from within the systems of the grid can cause issues with your supply. By having a proper power backup system based around UPS batteries you are removing most of the risk to your data from these issues. For example, a power spike from within the grid may blow out some of the wiring in your facility, causing a loss of mains power. With a backup supply of UPS batteries set to kick in automatically when a loss of power is detected, you are given the extra time and opportunity to asses the situation properly and take appropriate action.
Some decide to set up UPS batteries to replace the mains power indefinitely, but this can be expensive. A more sensible option is to set up a back up to provide you with enough energy to shut down your servers properly, redirecting the traffic to offsite backups.