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 beep, buzz or ring off as an alarm at a set time to wake a person up or for other reminders distributed control systems (DCS), 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. first-out alarm safety alarms, which go off if a dangerous condition occurs. Common public safety alarms include: civil defense siren also known as tornado sirens or air raid sirens fire alarm systems fire alarm notification appliance "Multiple-alarm fire", a locally-specific measure of the severity of a fire and the fire-department reaction required. smoke detector car alarms autodialer alarm, also known as community alarm personal alarm Video Alarm Verification System provides instant notifications upon the detection of a possible threat verified through a video feed. tocsins – a historical method of raising an alarm