Uninterruptible Power Supply

(Uninterruptible Power Supply) A device that provides battery backup when the electrical power fails or drops to an unacceptable voltage level. Small UPS systems provide power for a few minutes; enough to power down the computer in an orderly manner, while larger systems have enough battery for several hours.

In mission critical datacenters, UPS systems are used for just a few minutes until electrical generators take over.UPS systems can be set up to alert file servers to shut down in an orderly manner when an outage has occurred, and the batteries are running out.Surge Suppression and Voltage RegulationA surge protector filters out surges and spikes, and a voltage regulator maintains uniform voltage during a brownout, but a UPS keeps a computer running when there is no electrical power. UPS systems typically provide surge suppression and may provide voltage regulation. See surge suppression.Standby and Line InteractiveA standby UPS, also called an "offline UPS," is the most common type of UPS found in a computer or office supply store. It draws current from the AC outlet and switches to battery within a few milliseconds after detecting a power failure.The line interactive UPS "interacts" with the AC power line to smooth out the waveforms and correct the rise and fall of the voltage.Online UPSThe online UPS is the most advanced and most costly UPS. The inverter is continuously providing clean power from the battery, and the computer equipment is never receiving power directly from the AC outlet. However, online units contain cooling fans, which do make noise and may require some location planning for the home user or small office.

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Air Conditioner

The term air conditioning most commonly refers to the cooling and dehumidification of indoor air for thermal comfort.

In a broader sense, the term can refer to any form of cooling, heating, ventilation or disinfection that modifies the condition of air.[1] An air conditioner (AC or A/C in North American English, aircon in British and Australian English) is an appliance, system, or mechanism designed to stabilise the air temperature and humidity within an area (used for cooling as well as heating depending on the air properties at a given time) , typically using a refrigeration cycle but sometimes using evaporation, most commonly for comfort cooling in buildings and transportation vehicles.
The concept of air conditioning is known to have been applied in Ancient Rome, where aqueduct water was circulated through the walls of certain houses to cool them. Similar techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances in chemistry during the 19th Century, and the first large-scale electrical air conditioning was invented and used in 1902 by Willis Haviland Carrier.

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