urmet domus 1067/024, Installation Manual

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DS1067-063D
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LBT20064
2.3.2.5 Vibration detector
Also known as a seismic detector, this device picks up vibrations from the surfaces it is glued or screwed to and filters
them to prevent false alarms. When applied to a door or window, unlike the magnetic contact, it can signal an attempted
break-in before the door or window is actually opened. Indeed, by seeking to force the opening, vibrations are produced
that generate a signal of attempted intrusion.
2.3.2.6 Passive infra-red detector (IR)
This detector is equipped with one or more IR sensors that measure the rapid variations of infra-red traces of the
environment being controlled, indicating the presence of human beings, animals, or other "warm" objects that move. A
variation of this type generates a signalling by the detector. The effectiveness of the detector and the area covered are
changed by adjusting its sensitivity, changing the Fresnel lenses that focus on the sensor the controlled area or by
suitably masking the sensor itself. Some detectors make it possible to create a curtain covering, or to monitor a very long
and narrow vertical area, typically positioned parallel and not far from a group or windows or doors (hence its name). In
the intrusion alarm system, these detectors are used to control extensive spaces and obligatory passages, also being
identified as volumetric sensors.
2.3.2.7 Active infra-red detectors
This IR detector consists of two elements that face each other and are aligned to create an infra-red ray barrier. When an
object passes through the passage controlled by the detector, the rays are interrupted and the IR sensor generates a
signal. Technically, the detector can be created in two different ways. In the first way, the two elements contain one
sensor and the other light sources that emit a ray of infra-red light. In the other, an element contains both the sensor and
the infra-red light source and the other element consists of a mirror that reflects the IR light towards the sensor.
2.3.2.8 Microwave detector (MW)
This detector acts like a radar: it emits a radio signal and then detects and analyses the return signal (reflected waves).
When the return signal varies, due to something that has moved in the area covered by the detector, a signal is
generated by the detector. Unlike the passive IR detector, the movement are detected even if the person moving emits or
blocks heat. In the intrusion alarm system, these detector are used to control extensive spaces and obligatory passages,
also being identified as volumetric sensors.
2.3.2.9 Combined passive IR and microwave detector
This type of detector combines both technologies. The signals generated by the sensors can be compared to OR or AND
logic. In the first case it is sufficient for just one sensor to detect an anomaly for the detector to send a signal; in the
second case, both sensors must detect an anomaly for a signal to be sent. The two settings have a mirror effect. With
OR, the possibility of identifying attempts to intrude increase (what one sensor detects, the other sensor might not),
together with and increase in the generation of false alarms. With AND, the possibility of generating false alarms
decreases (the sensors must essentially confirm each other), but the sensitivity in detecting attempted intrusions also
decreases.
2.3.2.10 External detectors
The external detectors are essentially a specialisation of some of the types of detectors already illustrated herein.
An external detector has a more resistant protective casing that enables it to resist the elements as well as attempted
sabotage. Even the sensors used can have higher performance scores, but the operational principles are the same.
2.3.3 The signalling devices
This category includes all the devices capable of notifying people and other systems or equipment of a dangerous
situation for people or property placed under the protection of the intrusion alarm system.
2.3.3.1 Siren
The siren is a device that emits a very powerful sound that can easily be heard at a distance to warn of an attempted
intrusion. External sirens must have a power of at least 100 dB, while internal sirens must have a power of at least 80 dB
at 1 metre; if the sound is less powerful than these standards, the device is simply an acoustic signal. The siren is a
mandatory element. The minimum and maximum duration of the acoustic signal is established by law and by national
and local regulations and provisions. In addition to the external siren, the alarm systems must also have an internal
acoustic warning device. This warning device need not necessarily be a separate component, but may be a function
performed by some other device, like the control panel.
2.3.3.2 Flasher
The flasher is a visual warning usually combined with the external siren. The flasher signals a message through codified
sequences of lights and is visible at a great distance. In addition to signalling an attempted intrusion, based on the
capacity of the control panel the flasher can provide further information, like the visual confirmation of the system arming
and disarming from the external, the presence of alarms saved, etc.