Glossary: U

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UI System

A renewable energy system that is connected to the utility grid, selling excess energy back to the utility. Also called a utility-interactive system.

UL

Underwriters Laboratories. An approval organization based in the United States.

Uninterruptible Power Supply (UPS)

A power supply providing continuous, uninterruptible service—commonly used in telecommunications and computer networks.

Uninterruptible Power System (UPS)

A system designed to automatically provide power, without delay or transients, when the normal power supply is incapable of supplying acceptable power. Some UPSs also filter and/or regulate utility power.

UPS

Uninterruptible Power Supply

UPS Topology

Overall term describing the internal circuitry of a UPS. There are three basic UPS topologies: standby (off-line), line-interactive, and online.

Upwind

In relation to a wind turbine, toward the wind. An upwind turbine has its blades on the upwind side of the tower.

User-Replaceable Batteries

User replaceable batteries allow the user to easily exchange UPS batteries, once the unit has been turned off.

Utility Grid

Commercial electrical energy distribution system. Synonyms: Mains, Grid.

Utility-Intertie (UI) System

A renewable energy system that is connected to the utility grid, selling excess energy back to the utility. Also called a utility-interactive system.