Load Shedding

When a UPS is running on battery, it can automatically disconnect certain outlets or outlet groups after a set time or once the battery falls below a given level. The remaining energy then goes to critical loads such as the server, router and NAS, while monitors, printers and secondary systems shut down early.

This noticeably extends the runtime of important devices without adding batteries. The same idea is used in buildings with a generatorGlossary · Generators and solarGeneratorAn engine-driven alternator that produces electricity when the grid fails, often started automatically through an ATS. or in solar systems with batteries, where the distribution board disconnects non-essential circuits such as water heaters or air conditioners.

It requires a UPS with programmable outlet groups or a suitable PDUGlossary · Power qualityPDU (Power Distribution Unit)A rack power strip that distributes UPS power to the equipment, optionally with metering or remote control.. Plan from the start which device goes on which outlet, and label it on the rack so that a critical load is not moved by mistake.