Generally speaking, a motion detector is an electronic sensor that registers movements in the immediate vicinity. The motion sensors then generally function as light switches for lighting (e.g. for outdoor lights), but are also used in burglar alarm systems and for video surveillance. However, not only the applications but also the functions of motion detectors can be quite different.
Above all, a distinction must be made between motion detectors and presence detectors. As the name suggests, presence detectors determine the Presence, They have much more sensitive sensors and can therefore „recognise“ the presence of people even if they are not moving in the room. Presence detectors often also have a wider range of functions. For example, air conditioning and heating systems can also be controlled via presence detectors. As the presence detectors measure continuously, they also „notice“ when light is no longer required or when the heating or air conditioning can be switched off. They then trigger this process automatically. This is why they are mostly used in offices or other public buildings.
The motion detector, on the other hand, only registers movement once and then triggers the corresponding process, e.g. switches the light on when there is movement in the dark.
There are many different types of motion detectors. In addition to the aforementioned distinction between motion detectors and presence detectors, motion detectors are also differentiated according to function, in particular:
The usual range of commercially available motion sensors for home use is between 15 and 30 metres, the angle that can be detected (i.e. the detection range) is between 90° and 360°. There are therefore major differences between the detection areas and ranges of motion detectors.
There are four main types or categories of sensors: passive infrared sensors (PIR), ultrasonic sensors, high-frequency sensors and camera sensors. As the name suggests, PIR sensors utilise infrared light and detect changes in heat.
Camera sensors are hardly ever used for private use. They only detect people via the camera and are particularly precise. High-frequency sensors also have a high sensitivity and can work through doors and thin partition walls, for example. Ultrasonic sensors are mostly used for presence detectors.
Passive infrared sensors are the most widely used. PIR sensors are comparatively inexpensive, reliably detect heat sources and are completely sufficient for most private applications.
In addition to choosing the right motion detector, it is particularly important to ensure correct installation. Otherwise the detector may be ineffective. Particular attention should be paid to the following three aspects:
If the motion detector is used for Burglary protection, it should be installed in areas that are to be monitored. These include the front door, back and side entrances, basement windows, windows or terraces. A professional Security service can help you here.
The installation must be carried out in such a way that the covered surveillance area is as large as possible. Of course, it is important to know the range of the respective device. It may be necessary to install several devices to cover a specific room and ensure security.
Also important: The motion detectors should leave as few blind spots as possible. It is therefore important to know the detection area of the motion detector. Especially when installing several motion detectors, the installation must be checked carefully.
Last but not least, it is important to ensure the correct installation height. If the motion detector is to be used as burglar alarm, it is important that it is mounted high enough to prevent tampering. The height should be at least 2.50 metres, or even higher. However, it is also important to note the height up to which the respective motion detector may be installed. This can be found in the instructions for use.
This depends on the device - there are motion detectors that only react to larger objects or people. This is often the best solution. Alternatively, the surveillance area can be set so that it does not reach down to the floor, but only starts at „cat height“ or „dog height“, from about 50 cm. This can be adjusted directly on the sensor. The motion detector can also be positioned so that it does not reach the pavement or road - this also avoids a lot of unnecessary triggering.
There are various scenarios for connecting a motion detector - so there is no general answer to this question. Essentially, it depends on the location and the nature of the motion detector. For example, surface-mounted motion detectors are of course installed differently to flush-mounted motion detectors; in addition, different things need to be taken into account outdoors than indoors.
Wall mounting is much easier with surface mounting than flush mounting, as the walls have to be broken open for flush mounting. On the other hand, flush-mounted motion detectors do not protrude unattractively from the wall and are also more difficult to manipulate, especially outdoors. In addition to wall mounting, ceiling mounting is of course always an option; however, this depends on the selected motion sensor and its detection area. In outdoor areas, of course, wall mounting is usually the only option.
From a purely electrical connection point of view, however, installation is very simple. There is a connection with two-wire technology or three-wire technology. The black live cable is connected to terminal „L“, the blue neutral conductor to terminal „N“ and the third contact to the remaining terminal. If there is no neutral conductor, the other two cables are connected in the same way as with three-wire technology.
Of course, there are also many motion detectors that are installed as part of a smart home, e.g. to control LED lights (e.g. those from Steinel, but of course also products from other manufacturers). It is then also necessary to programme the devices in the app so that the functionality is optimal.
The price of motion detectors depends entirely on the category (infrared, camera, etc.), equipment and scope of the system. A radio-controlled, professional system from Steinel, for example, has its price. Motion detectors with an alarm system are also somewhat more expensive. However, motion detectors are available at an affordable price, for example for activating outdoor lights and LEDs, via cable or wirelessly. There are also high-quality devices from well-known manufacturers such as Steinel, ABUS, BTR, Idena, Kopp, Philips and Siemens at a favourable price.
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