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Alarm
From Wikipedia, the free encyclopedia
(Redirected from Alarms)
For other uses, see Alarm (disambiguation).
An alarm (French: ? l'arme - "To the arms") gives an audible or visual warning of a problem or condition.
Alarms include:
burglar alarms, designed to warn of burglaries; this is often a silent alarm: the police or guards are warned without indication to the burglar, which increases the chances of catching him or her.
alarm clocks can produce an alarm at a given time
Distributed control manufacturing systems or DCSs, found in nuclear power plants, refineries and chemical facilities also generate alarms to direct the operator's attention to an important event that he or she needs to address.
Alarms in an Operation and Maintenance (O&M) Monitoring system, which informs the bad working state of (a particular part of the) system under monitoring.
safety alarms, which go off if a dangerous condition occurs. Common public safety alarms include:
tornado sirens
fire alarms
"Multiple-alarm fire", a locally-specific measure of the severity of a fire and the fire-department reaction required.
car alarms
Community Alarm or Autodialer alarm (medical alarms)
air raid sirens
Personal alarm
tocsins a historical method of raising an alarm
Alarms have the capability of causing a fight-or-flight response in humans; a person under this mindset will panic and either flee the perceived danger or attempt to eliminate it, often ignoring rational thought in either case. We can characterise a person in such a state as "alarmed".
With any kind of alarm, the need exists to balance between on the one hand the danger of false alarms (called "false positives") the signal going off in the absence of a problem and on the other hand failing to signal an actual problem (called a "false negative"). False alarms can waste resources expensively and can even be dangerous. For example, false alarms of a fire can waste firefighter manpower, making them unavailable for a real fire, and risk injury to firefighters and others as the fire engines race to the alleged fire's location. In addition, false alarms may acclimatise people to ignore alarm signals, and thus possibly to ignore an actual emergency: Aesop's fable of The Boy Who Cried Wolf exemplifies this problem.
[edit] Etymology
"Alarm" came from Old French '? l'arme' = "to the weapon", telling armed men to pick up their weapons and get ready for action (because an enemy may have suddenly appeared).
[edit] See also
Alarm management
Burglary
Burglar alarm
Clock
False alarm
Fire alarm notification appliance
Physical Security
Smoke detector