The blocking of overly high-voltage utility power by a UPS before it reaches the attached devices. Joule A unit of energy. The surge suppression ability of a UPS is often quoted in joules. A process by which UPSs filter utility power to ensure that the proper voltage is sent to devices. Line-interactive Refers to a design in which a UPS monitors and filters utility power before passing it to the attached devices.
Battery power is used only when the incoming voltage dips below or rises above acceptable levels.
Load shedding A procedure by which the UPS switches off selected devices to save power or prolong battery runtime. Noise A phenomenon caused by lighting, load switching, generators, and other sources of interference that disrupts the utility power's smooth sine wave and may produce glitches and introduce errors in programs and data files. The batteries are always online, so power is never interrupted by switching, even during a blackout. Any significant alteration in the flow of 120V utility power, such as a spike, surge, brownout, or blackout. Spike An instantaneous, dramatic voltage increase usually caused by a lightning strike or when power is restored after a blackout.