ChiliTec 21521 Manual Del Usuario página 6

Functional principle of PIR motion detectors:
The PIR sensor uses the pyroelectricity of its receiving surface to react to a change in
temperature, caused by a change in radiation flux (mainly due to heat radiation in the mid-
infrared; wavelength approx. 10 µm) from people, animals and motor vehicles in its immediate
vicinity. It does not react to static differences in heat that are caused naturally, for example by
solar radiation - it can only perceive changing signals, for example when a person enters the
detection area of the sensor.
In front of the actual sensor - at a focal length distance - there is a spherical or cylindrically
arched dome made of small converging lenses made of visually whitish-cloudy plastic, which is,
however, clearly transparent in the infrared. This multiple lens collects infrared light from a
corresponding number of discrete directional sectors onto the small sensor surface. Visible light
is scattered back more. Depending on the lens arrangement, the sensor sees the environment
as if through spread fingers, (vertical) louvre slots or the grid of a perforated plate. If an object
or living being moves with a surface temperature sufficiently higher (seldom: lower) than the
background across these compartments from visual sectors, and is the warm, therefore lighter
in the infrared area, conveniently about as wide as a single visual sector There, so the sensor
senses the chronological sequence warm-cold-warm. Because the heat source is sometimes
visible, then disappears in the shadow of a "finger" and reappears in the viewing slit of the next
finger gap. The temperature change at the sensor, which is somewhat delayed due to the
thermal capacity, causes an electrical signal that is processed and amplified in order to switch on
light via a relay.
In addition to transverse movement to the visible sector stripes, entering such a stripe for the
first time or approaching it sufficiently quickly (ie "getting bigger") is also detected. Motion
detectors are usually adjustable in sensitivity and coupled with an adjustable twilight switch.
PIR sensors only receive rays emitted by objects and do not emit any radiation themselves,
which is expressed by the term passive infrared sensor. PIR sensors react poorly when an object
moves towards or away from them. This is due to their functional principle, since the movement
detection takes place on the basis of a temperature change on the sensor surface and
movements across the detection area can be better recognized due to the predominantly
transverse arrangement of the lens area. PIR detectors can incorrectly be caused by underfloor
heating that is warming up
to be triggered.
Example use as a light switch:
An infrared motion detector usually has a built-in twilight switch, which ensures that the lighting
can only be switched on by the actual motion detector when it is dark. If a heat source moves in
front of the detector, it switches the lighting on for an adjustable period of time and switches it
off again after the set lighting time has elapsed. Most motion detectors have two adjusters
(potentiometers): for the switch-on time: defines how long the consumer should remain
switched on for the ambient brightness (light-dark border): defines from which darkness
threshold the detector
should be sharp.
There are two-pole and three-pole detectors. Two-pole detectors do not need a neutral
conductor, as they receive this via the downstream light bulb. They are not suitable for other
light sources. Three-pole detectors require a neutral conductor and switch the following load via
a small relay, so that all lamps are up to the maximum load
possible.
Source: www.wikipedia.de https://de.wikipedia.org/wiki/
Bewegungsmelder - as of mid-2015
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operation manual
- Product data sheet page 3/3 -
EAR (WEEE): DE25841852
LUCID Packaging Act: DE5562476395648
GRS (UBA register) No .: 21003466
Status: 07/2019 - Ver. 1.00