What’s the difference between a UPS and a backup generator, and do I need both?

A UPS system provides instant battery backup to keep critical connected loads running. Battery runtime (or duration) is typically 5-30 minutes, which is suitable for most applications. Where a longer runtime is required, the uninterruptible power supply is installed with a larger battery set, usually an externally connected battery extension pack or a standby power generator.

As generators can take up to 1-2 minutes to come up to full cycle power after a cold start, the UPS battery covers this period, preventing the connected loads from a power outage and a break in electrical supply. Once up to and stable, the UPS input then synchronises to the generator supply and reverts to battery charging. The process is seamless to the connected loads, as the UPS inverter constantly powers them. When the mains power supply returns and is stable, the UPS system synchronises its input to the mains, and the generator powers down. An Auto Mains Failure (AMF) panel monitors and controls generator start-up and power-down.