How much backup time can a 3kVA UPS (uninterruptible power supply) provide?

A 3kVA uninterruptible power supply will have a built-in battery pack and the amount of runtime the UPS can provide when there is a mains power outage is dependent on the load connected. At 80% load a typical 3kVA/3kW UPS can provide 5-10 minutes of battery runtime. This can be extended by adding plug-in battery packs if the UPS has this facility or oversizing the uninterruptible power supply. For long runtimes, in excess of 7hours, standby power generators can be more cost-effective than a large battery set.