"Undervoltage" occurs when the nominal voltage drops below 90% for more than 1 minute.

A complex comprising of any combination of habitats with transfer chambers, and may include a tethered or untethered submersible unit and its launch and recovery system, (ABS).

A permanently unmanned submersible vessel containing equipment that is to be protected from water. It may be anchored to the ocean floor, (ABS).

A system comprising of one or more units with all their support components necessary to conduct a specified manned underwater operation such as a diving system and an underwater complex, (ABS).

Self-propelled crafts intended for underwater operations that may or may not be independent of surface support, (ABS).

A person participating in an underwriting syndicate or group that provides insurance cover for a vessel.

The manner in which ships and other vehicles of transport are insured.

The term "unglazed air collector" refers to a solar air heating system that consists of a metal absorber without any glass or glazing over top.

A new space-saving lifeboat davit system for cruise vessels, developed by Schat-Harding.

Modular, embedded control system for control and monitoring of diesel and gas engines developed by Wärtsilä.

The MacGregor universal twistlock that can be used as a semi-automatic twistlock, an automatic fixing cone or bottom automatic fixing cone.

A common source of unintentional backfeeding is an electrical generator (typically a portable generator) that is improperly connected to a building electrical system.

An uninterruptible power supply or uninterruptible power source (UPS) is an electrical apparatus that provides emergency power to a load when the input power source or mains power fails.

The unit commitment problem (UC) in electrical power production is a large family of mathematical optimization problems where the production of a set of electrical generators is coordinated in order to achieve some common target, usually either match the energy demand at minimum cost or maximize revenues from electricity production.

A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity.

The UNFCCC secretariat (UN Climate Change) is the United Nations entity tasked with supporting the global response to the threat of climate change.

United States customary units (U.S. customary units) are a system of measurements commonly used in the United States since it was formalized in 1832, developed from English units which were in use in the British Empire before the U.S. became an independent country.

As energy is defined via work, the SI unit of energy is the same as the unit of work – the joule (J).

The Universe of Energy was a pavilion located on the eastern side of Future World at Epcot, a theme park at the Walt Disney World Resort in Bay Lake, Florida.

The proces of disconnecting a generator or plant from the grid in a controlled manner.