Burglar Alarm Detectors and Sensors
All intruder alarm systems require at least one detector. Detectors range from simple magnetic contacts to sophisticated Passive Infra-red (PIR) detectors. Other commonly used detectors are vibration detectors (also termed shock and inertia), break-glass detectors, and dual technology detectors (combined PIR and Microwave).
The majority of detectors are Normally Closed (NC) devices, i.e. the detector allows current to flow through it when in a non-alarm state. When the circuit is broken, it is detected by the Control Panel and an alarm state is signalled. Multiple NC detectors can be daisy-chained into the same loop.
Some detectors have to be connected as Normally Open (NO) devices e.g. pressure mats and some other types of detector may be optionally configured to operate as NO devices. Normally Open devices cannot be daisy-chaind together - each pair of detector wires must be connected directly to the Control Panel.
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 | Passive Infra-red (PIR) Motion Sensors |
 | Magnetic Contacts |
 | Vibration Detectors |
 | Break-glass Detectors |
 | Smoke and Heat Detectors |
 | Pressure Mats |
 | Photo-electric Beams |
 | Personal Attack Buttons (PABs) |
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