As electricity tariffs increase, more and more attention is being paid to its energy saving, and they are of particular importance to private consumers. Among the known methods of saving electricity, automatic devices that control the on and off lighting in controlled spaces stand out. Street motion sensor - a special sensitive device that allows you to turn on the light only when absolutely necessary.
Areas of use
The first samples of motion sensors (DD) were used mainly in the protection of objects. With their help, an alarm was generated, warning about the penetration of unauthorized persons into the territory. Over time, manufacturers decided to expand the protective functions of the sensor, which, after refinement, was able to turn on lighting devices.
Since a wide variety of illuminators are installed in open spaces, the scope of wireless sensors is very extensive.
Together with the lighting device they are used in the following situations:
- If necessary, turn on the spotlight in front of your house or at the exit of the garage.
- For security lighting of personal areas (as part of landscape design systems).
- In order to highlight the facades of buildings.
- At any objects where protection against penetration by the sudden inclusion of a powerful illuminator is possible.
In addition, outdoor motion sensors are used in hotel and office facilities, as well as in educational institutions, sports facilities, parking lots and trading floors.
Principles of operation and types of sensors
The essence of the functioning of street motion sensors to turn on the light: when a constantly moving object is detected, the sensing element is activated and sends a signal to the actuator, which turns on the illuminator for a certain time. After it expires, the lamp or spotlight turns off before the next operation.
As sensitive sensors in such a system, various devices are used that work in conjunction with lighting equipment. Four types of motion detectors are known, characterized by a built-in sensor element:
- IR sensors
- modern ultrasound devices;
- microwave or microwave elements;
- Hybrid sensors combining several types of capabilities.
Street infrared DD
IR sensors are among the most common types of detectors, the principle of which is based on the detection of movements in the control zone. They are able to turn on during the transformation of the overall physical picture, due to the heat generated by a living organism. Any changes in the temperature state or position of the object are recorded by a sensitive device.
Of the two known varieties of IR sensors (active and passive), only the latter are used together with illuminators.
Despite the weak sensitivity, shorter range and significant error, passive products are in great demand, due to their comparative cheapness.
Ultrasonic
Devices of this class operate due to the effect of reflection of the sound emitted from them from a moving object. After receiving the reflected signal, the sensor recognizes changes in its spectrum and generates a pulse to turn on the lighting. The frequency of the ultrasound generated by the sensor is in the range of 30-40 kHz and is practically not captured by the human ear.
These frequencies nevertheless have a certain physical effect on the human body, and most often they are unsafe for health. Therefore, ultrasonic sensors are recommended only for use outdoors.
Microwave
The operation of these devices is based on the Doppler effect, which extends its effect to microwave signals. When moving any object, the frequency of the signal reflected from it changes its value. The magnitude of this change is proportional to the speed of movement of the person who fell into the sensitivity zone of the sensor. This method also has its drawbacks, which are manifested in the fact that any random obstacles interfere with the operation of the system.
Factors to consider when selecting and tuning
Before choosing a sensor, you need to immediately determine in which place this device will be used, as well as with the following important points:
- mounting method;
- degree of security;
- total power of switched lighting equipment.
On the market are models with a wide variety of characteristics that differ not only in their appearance, but also in functionality. They are able to perform protective functions in various conditions of visibility and are considered all-weather. These devices differ in the following parameters taken into account when setting them:
- the configuration of the field of view, the correct choice of which determines the reliability of the device (no false positives);
- the ability to accurately set the moment the light source is turned on and off;
- different viewing angles, ranging from 180 to 360 degrees.
Sensors with a viewing angle of 180 degrees are installed in the areas of "input-output" and are mounted on the surface of the walls.
Instrument Installation
Particular difficulties with the installation of sensors usually do not arise. For their installation, a place is chosen from which the work item reliably fixes the movement of objects falling within the radius of action. It is chosen so that when the spotlight is turned on, a complete overlap of the controlled space is ensured.
A number of DD models provide for the possibility of using a backup battery connected in the event of a power failure.
In this case, when installing the product, it will be necessary to provide a separate place for the battery (if an external battery is used), which is reliably protected from the weather.
Connection and setup
The procedure for connecting the device to the network depends on the configuration, which varies with individual models. In some cases, the sensor and the illuminator are placed in a common housing and have an electrical connection. To connect them to the mains, you need a standard outlet, which is included in the package. Sometimes they are delivered separately and need to be worked out by the switching scheme, which would include the following options:
- direct inclusion of the illuminator;
- use of a switch mounted in parallel;
- a combined version in which several sensors or illuminators are turned on (due to the high cost it is used very rarely).
In the first case, lighting can only be connected when a person appears in the sensitivity zone - the light comes on after the DD is triggered. The second option is considered more universal, allows selection according to user preference. You can leave the device to work in automatic mode (the switch is locked) or turn on the light fixture manually. In the latter case, the circuit is switched in parallel (one way or another - to choose from).
System setup with DD is carried out according to the instructions attached to each device. It involves the following procedure:
- The correct direction to the emitted or reflected signal is selected to the maximum of its fixation by the receiver.
- The sensor is configured so as not to be triggered by accidental interference.
- At the final stage, they try to combine the two settings until the system is stable, in order to get good statistics.
When setting the sensitivity limit, the sensor in open spaces is adjusted to a minimum.
With low illumination of the controlled area, the exact value is selected empirically. At the final stage of tuning, it is further adjusted.
