How does the light sensor work. Why do you need a light sensor in your phone, how to turn it on

Owners of their own homes often think about which light sensor to choose for street lighting. After all, it is very convenient when the light automatically turns on at night and turns off in the light. There are 2 options for this: put a photorelay or an astrotimer. Since the first device is more common due to its low price and availability, we will consider it first.

In this article:

Photo relay device

This device is called by different names. For example, photocell, light sensor, photosensor or photosensor, light sensor. However, the most common name is "photorelay". With it, you can automatically turn on the light at night and turn it off at daylight.

It is based on photoresistors, photodiodes and phototransistors. When the light becomes weak and insufficient, they change the parameters. When certain values ​​​​are reached, the contacts in the relay close and the power supply to the lamps begins. Accordingly, with increasing illumination, the parameters of the photosensitive elements begin to change again, but in the opposite direction, and the contacts open.

When choosing, you first need to decide on the voltage that will be in the network: 220 V or 12 V. Then select the protection class. The minimum can be considered IP44. The higher the class, the better. This protection marking means that objects smaller than 1 mm in size will not fall into the light relay, and it is reliably protected from rain. It is also worth paying attention to the fact that the temperature regime of operation exceeds the maximum and minimum temperatures.

The output power of the light relay will depend on the total power of the connected lamps and current. To avoid overloads and breakdowns, it is better to take a device with a power reserve.

In some models, you can adjust the sensitivity of the photosensor. This is very convenient, for example, in winter when it snows. Reflected light can be perceived by the light sensor as dawn and will turn the lamps on and off. It is worth paying attention to the presence of a delay in operation. By setting it for 5-7 seconds, you will prevent a power outage when light hits the sensor, for example, from car headlights.

Where to put the photorelay and how to connect it?

Properly chosen place for the device will ensure its correct functioning. Consider the following:

• the sun's rays must fall on the photo relay, i.e. it must be placed in the open air;
• do not place artificial light sources near the sensor;
• place it at such a height that the headlights from passing cars do not fall on the photocell;
• the height should be convenient for maintenance (washing and removing snow).

Summing up, we can say that choosing a place is not the easiest. Sometimes you need to change it several times to find the best option. Sometimes LED spotlights or a street lamp are connected to the relay and the device is hung on a pole. But this is an irrational decision, because. the box needs to be periodically wiped from dust, each time it is inconvenient to climb a pole for this.

Connecting the light sensor is quite simple. 3 wires come out of the device: phase and zero to power the relay, switching phase to connect the lamp. The wires are connected in a junction box, which must be sealed, especially for the street. If you plan to connect only one lamp, the junction box can be installed next to the relay. Connecting a powerful backlight is best done through a starter.

A motion sensor is used to turn on the light only when a person is present. In this case, the sensor is connected after the photo relay. It will only operate in the evening. In the motion sensor, you can also adjust the turn-on delay so that it is not triggered by the movement of a branch or a bird flying by.

A photo relay from any manufacturer has 3 wires for connection - 1 is always red, 2 others may have different colors from different manufacturers (usually blue / dark green and black / brown). Red goes to lights or connects to a motion sensor. Connect blue or dark green to the neutral wire of the power cable and lamp, and connect the phase to black or brown. If the relay has non-standard wire colors, you should read in the instructions which wire should be connected where.

Light sensitivity is adjusted by rotating the small plastic disc on the bottom of the relay. There are always pointers next to it to indicate in which direction to rotate it to increase or decrease the sensitivity of the photocell.

To adjust the light threshold, the following method is usually used: the regulator is set to the lowest sensitivity. In the evening, when backlighting is needed, the disk is smoothly twisted until the relay starts working. The setting is considered complete when the light comes on.

Despite the fact that the sensors are designed to automatically turn on and off, they have a special toggle switch or button that allows manual control of the device.

Astronomical timer

This device is inherently different from a photorelay. Automatic switching on of lighting occurs at a predetermined time. The astro timer is programmed with the time when it gets dark and light in different regions. And he makes adjustments using GPS. It is only necessary to enter the coordinates of its location, the current date and time. Based on the entered data, he selects the appropriate program and works.

This device has a number of advantages over a photorelay. The latter can work in cloudy weather or, on the contrary, go out in the middle of the night due to light falling on it. The astronomical timer does not have such a drawback. It can be installed anywhere outdoors or indoors. On it, you can shift the on and off of the lighting by 2-4 hours. Its only drawback is the high price.

If you choose a device for lighting streets or places where a person stays for a short time (gate, toilet, etc.), a photorelay will do. But if there is no desire to depend on weather conditions and take care of the photocell, then it is worth choosing the optimal astrotimer model for certain conditions and needs.

A twilight switch, light (illuminance) sensors is a device for automatic control of artificial (electric) light sources. Depending on the degree of illumination of the surrounding space, the sensor is able to send a signal to turn on / off lamps, spotlights, lanterns and other lighting devices. Properly installed and programmed equipment works without human intervention. In other words, a light sensor (twilight switch) is an automatic switch that monitors and controls the brightness of the lighting in a certain area or room. At dusk, it will turn on the light, and after sunrise it will turn off. When using this equipment, you can save energy up to 10-15%.

Device, installation and principle of operation of the light sensor

The main field of application of light sensors is automatic light control. They are used to automate lighting in garages, entrances of residential buildings, on roads, home gardens of private cottages and in other places where during the day the space is lit by natural light, and at dusk - by electric light.

The principle of operation of light sensors is to monitor the level of light radiation that enters the field of "visibility" of the device. Light beams are focused by a photocell (light relay) and directed towards the detector. When a certain brightness threshold (minimum or maximum) is reached, the detector generates a voltage that is used by the device as a signal to close the circuit and block electrical devices. It is this signal, received as a result of the generated voltage, that turns on the lamp at dusk, and turns it off at dawn. In order to save money at night, it is possible to turn off the sensor for a certain time.

Thus, any light sensor (street, home) is a photo sensor - a primary converter, an element of a regulating, signaling, measuring or control device of the system. It converts the monitored and controlled quantity into a signal that is easy to use.

The required illumination at which the light sensor is triggered is 5 - 50 lux. It can be adjusted depending on the location and installation conditions.

Equipment classification

Sensors for automatically turning on the lighting differ in several ways:

• in size - they are small-sized (built into lighting fixtures) and standard (installed independently);
• according to the control method - they are divided into programmable, automatic, with the function of night energy saving, with the possibility of forced shutdown;
• by load power - up to 1000, up to 2000, 3000 W;
• by type of load - energy-saving, LED, fluorescent or halogen lamps 220V, incandescent 220V, halogen 12V with an electronic transformer (or with a winding transformer);
• according to the version - overhead (wall-mounted), internal (built into the electrical panel on a DIN rail) or outdoor installation;

In some cases, lamp control also uses the connection of a motion sensor for lighting, which reacts to the presence of a person.

At present, light sensors of such brands as CAREL, HAGER, ELTAKO, GIRA THERMOKON and others are common. The price of a light sensor depends on the type, functions of the equipment and the manufacturer.

Proper lighting in the evening and at night allows you to create an indescribable atmosphere in the yard. But walking and turning on each lamp separately is a hilarious task. That is why it is better to use a light sensor. He independently evaluates the received data and turns the lights on or off. There are a considerable number of them and everyone can offer some kind of zest. How not to get lost among the abundance and what needs to be done to connect on your own? This is what will be discussed in the article.

How it works

The light sensor is not quite the usual name for the device. Most often, masters call it a photorelay. In stores, you can also see it on the shelves under the name of the dusk sensor, day / night sensor, photoelectric switch, dawn control sensor, photosensor, photosensor and others. The essence of the functioning of the device does not change from how it is called. It provides an automatic supply of electric current to the consumer when the sun sets and stops it when the sun appears on the horizon in the morning.

The principle of operation of the photorelay is based on the interaction of light waves with certain substances. In this case, the properties of the latter change. For these purposes, special transistors, diodes and resistors have been developed. All of them have a photo attachment. Some of them close or open an electrical circuit depending on the sun's rays. Photoresistors change their bandwidth by increasing or decreasing resistance. All these devices deserve attention. Some of these photo sensors will be more relevant for one area and perform worse in another. Therefore, the correct choice of light sensor is important.

What is the sensor made of?

When buying a photorelay, the client receives at his disposal a box in which all the components of such a photorelay are located. Its elements are:

• photosensitive component;
• a switch that reacts to twilight;
• interval relay;
• sensitivity relay.

Some photo relays may use several photosensitive elements, which give a more accurate assessment of the quantity and quality of incoming light. They are able to determine the wavelength that affects the photosensor. This is necessary so that the photo relay does not work on lighting from a lantern, but only on sunlight. In some models of the photo relay, additional tuning resistors are mounted, which make it possible to set the interval during which the lighting will be turned on by time, and also after what period after sunset the power from the photo relay will be supplied.

Not only ordinary incandescent lamps can act as end consumers that will be used in tandem with a photoelectric relay. It can be LED strips, as well as gas discharge lamps. The photorelay is able to power any number of them with the correct connection. Some photo relays have a built-in signal amplifier that is fed to third devices that control the lighting system. In order for the switching process to occur as reliably as possible, thyristor switches can be installed in the photo relay, which transmit the signal from the photo relay as quickly as possible.

Varieties of sensors

All photorelays can conditionally be divided into several groups. Each of these photorelay groups will be united by one of the indicators of their characteristics. Among the groups of photo relays, there are:

• by rated voltage;
• by rated load;
• according to the tightness of the body;
• according to the method of installation;
• for additional controls.

Light bulbs that are connected to a photo relay can not necessarily operate from 220 volt sieves, so there are separate models of photo sensors that are designed for nominal voltages of 12, 24 and 36 volts. Usually, the photo relay indicates the rated current that the device can withstand. It is by this parameter that it is easy to calculate the load that the photorelay will withstand. For example, if it is written on the photo relay that it is rated for 6 amperes, then at 220 volts this means that the photo sensor can easily pull lighting with a total power of 1.32 kW. To do this, it is enough to use the formula P \u003d UI, that is, multiply the current by the voltage. According to the installation method, the sensor can be outdoor or indoor. And it will depend on it

Advice! Always buy a photorelay with a power margin. This will allow you to subsequently connect a large load to the photo relay, if necessary.

You can judge where the photorelay can be installed: on the street or in the house, by what degree of protection according to the IP standard is indicated on it. If there is a number 68 after these letters, then such a sensor can be safely hung in the pouring rain, and it will not fail. The shape of the photorelay body can be very diverse: square, rectangle, cone, ball and others. Choose what you like best and matches the place of installation. Some photo relays have additional features, such as sensitivity adjustment. It is especially needed in winter when it snows. The latter perfectly reflects light. Walking at night when there is snow is less scary than without it. But the photorelay can perceive its reflection as the onset of morning, so the lighting can turn on and off at an unpredictable frequency.

Note! Combined photorelays are available for sale. They can be paired with a motion sensor. In this case, the light will turn on only at night and only when a certain movement is observed in the controlled area.

Application Benefits

The advantage of using a photorelay is difficult to overestimate. This not only saves time, but also money. Some buildings require façade lighting to be turned on in the evening to create a unique spatial effect. Everyone likes it when street lights turn on in a timely manner. Photorelay can be used in tandem with video surveillance systems. Some types of the latter require good light for a high-quality picture. Photo relays are used not only for lighting. In some cases, photosensors are used for irrigation systems. As soon as the sun hides, the irrigation pumps turn on. This is done in such a way that, under the scorching sun, the leaves of the plants are not scorched.

If you constantly monitor your electricity bills, then you will definitely see a decrease in the number after you start using the photosensor. Manufacturers are trying to simplify the assembly and connection of the light sensor. This means that for its installation there is no need to involve a professional, and everything can be done independently. The photo sensor makes it possible to increase the safety of your own home. Houses with poor lighting are often chosen for hacking. The photorelay will work even when no one is at home and create the effect of the presence of the owners. For the most part, the photo relays correspond to the declared characteristics, so there is no need to talk about shortcomings. There can only be differences in models.

What to choose

Choosing a photorelay for lighting is for specific needs or a project. To do this, several factors must be taken into account:

• total lighting power;
• position of the area for lighting;
• lighting voltage;
• location of the sensor;
• lighting operating time;
• availability of a surveillance system;
• the need for additional modules.

Next to each item of this list it is necessary to make the required notes. This will allow you to quickly analyze the characteristics of the photorelay mentioned above. In some cases, it will be necessary to install several light sensors.

Connection methods and schemes

Anyone who does not have a special education in the field of electrical engineering will be able to figure out how to connect a photorelay for lighting. If in general to describe the scheme of connecting the photorelay to the circuit, then it boils down to the fact that the supply wire of the power supply is inserted into the sensor itself. From the photorelay, a phase is connected to the consumer, and the neutral wire is supplied separately from the shield. There are three main methods for connecting a photo relay for lighting in a circuit:

• with wiring in a box;
• with wiring in the sensor itself;
• load connection through the starter.

The figure shows how the wires are connected not in the sensor, but in a special junction box. It is this method that is considered competent. In this case, the box must be purchased sealed. It should have rubber gaskets under the cover, as well as in each inlet. Only in this case it is possible to guarantee the absence of oxidative processes on the contact pads.

There are projects where the total power of the entire system is ten times higher than the rated power of the photorelay. In such cases, a starter will be required. The essence of the scheme will be that the power to all consumers will not go through a photorelay, but through a contactor. The photo sensor itself will only be a signaling device that will give a command to close or open the contacts of the starter. This method is the best from a security point of view. The service life of the photorelay when using the starter increases several times. An example of such a connection diagram can be seen below.

Not all manufacturers indicate the purpose of the wires that are on the photo relay for street lighting. Usually there are three. The power cable is connected to two of them. Usually it is blue and black. Zero is brought to blue from the shield, phase is applied to black or brown. There is also a third red wire. It serves to supply voltage from the photorelay to the consumer. The diagram shows that a neutral wire also goes separately from the box to the consumer.

Finding a mounting location

Knowing how to connect is not all that is needed to install a sensor for street lighting. For it, you need to choose the right place and height for installation. In this case, it will correctly determine the level of illumination. The first factor is the need for an open area. That is, there should not be any obstacles that would prevent sunlight from reaching the sensor. Therefore, it is better not to place it under the roof. The height of the photo relay should be such that it can be easily reached if necessary to perform maintenance. But the light from the headlights of cars must be lower so that the sensor does not work on them.

At night, when there are sources of artificial light, the sensor must be removed as far as possible so that the light of street lights or light from windows does not fall on it. In some cases, it will be necessary to change the position of the street lighting photo sensor several times until the best option is found. Some tips can be gleaned from the video:

Advice! Do not place the street light sensor far from your home or other premises. This will make it easier to control and clean. Don't place him on a pole that he will control, as this will only cause trouble. This approach will require additional cable footage, but in the end, such costs will pay off in time savings.

Cheap sensor models do not support any additional settings. They exhibit average positions that are maintained throughout the entire period of operation. Other solutions have two regulators. They will be needed after the complete installation and launch of the entire system. The regulator is often a small recess for a screwdriver with a scale on the body. One of them allows you to adjust the sensitivity. That is, the threshold at which all lighting will be turned on. This is a very useful element that allows you to maintain the required values ​​​​on days of various lengths. To select the correct position, it must be put in the leftmost position or minus. As soon as evening comes and lighting is already needed, then you will need to turn the regulator to plus until the street lighting starts. It is worth doing this very smoothly so as not to miss the moment of operation.

Is there an alternative

In some areas, the installation of a photorelay is difficult due to the relief or the abundance of trees. In such cases, you can use the modern operating time, which is tied not to the level of illumination, but to other data. Such a device is called an astronomical timer. Due to the exact time of the earth's movement around the sun and its axis, it is easy to predict the time of sunrise and sunset in a particular area. That is what this device does. During the first turn on, you will need to indicate your location using coordinates, as well as the exact time. Thanks to the built-in firmware, the device will turn street lighting on and off.

The advantage of such a solution over a photorelay is the independence of what is happening on the street. In rainy weather, when there is little light on the street, the photorelay may mistakenly determine that dusk has come and it is necessary to turn on the lighting. The astro timer is time and coordinate oriented, so it is not affected by such changes. If the photorelay is dirty or crushed with snow, then there may also be false positives. For a timer that works by coordinates, there is no need to allocate a special place for installation. It can be placed in any convenient place in the house. Some models allow you to adjust the start delay. The only drawback may be the price, but you have to pay for quality.

Note! Instead of a photo relay, you can use a regular timer. It will supply power to the lighting at the specified time. It is not as convenient as a photorelay, but it can also help out well.

Conclusion

With the above information, you can easily purchase a photocell yourself and install it. You will appreciate the advantages of a photorelay over manual switching on of lighting. If you have a unique illumination project installed in your yard, then it will delight you every time after sunset.

What is a light sensor and what is it for? This device has many names, for example, a light sensor, a light control switch, a twilight switch, a photo sensor or a photo relay. It is intended solely to save electrical energy and is a small device with various microcircuits inside, connected to an electrical circuit.

Nowadays, there are a huge number of various devices of this type. For example, a motion sensor that closes the circuit when there is movement in its field of activity. An individual feature of the photorelay is the ability to change the power of artificial lighting depending on the level of natural light. Recently, these sensors are gaining more and more popularity and are widely used together with lamps for street lighting at night, with lighting fixtures in stairwells, etc.

In this article, we will just talk about how to connect a photo relay, and a detailed diagram for connecting a photo relay for street lighting will be presented.

The principle of operation of the twilight switch and its connection diagram

This device has a simple structure. A special part is installed inside it, called a photosensitive element. Usually it is a photodiode or a photoresistor. Each of these elements is able to increase or decrease the resistance inside the sensor, focusing on the level of natural light. This process causes the voltage inside the photoelectric relay to increase or decrease, and the lighting fixture starts to produce artificial light or turns off.

In simple terms, the light sensor works like a switch, but it happens automatically. The amount of light flux at which the photo relay (switch-on sensor) is triggered is manually adjusted and does not require special knowledge.

Design features of light sensors

These devices are similar in design. As a rule, sensors are a small plastic box that is mounted on the wall or on the body of the lighting fixture itself.

Installing a photorelay takes a little time and saves a sufficient amount of electrical energy. The twilight sensor pays for itself in the shortest possible time.

Connecting a photorelay for street lighting in high power conditions involves minor changes in the installation process. In this case, the device is connected through a magnetic starter.

If it is planned to install several light sensors, then in this case they are connected in parallel.

There are also devices that have a remote sensor. This design feature allows you to install a lighting device together with a photorelay in places inaccessible to natural light.

Modern technologies do not stand still, the lighting control scheme is changing along with them. Adjusting the brightness of the light, lighting time and other indicators can be adjusted and maintained automatically via a computer and the Internet.

Photo sensor connection diagram

The figure shows a generalized standard scheme for connecting a light sensor. Manufacturers of these devices are constantly improving the design and making adjustments to the schemes and modes of operation. It all depends on the ratio of the cost of the photo relay to the quality of its manufacture.

Principles of measuring the level of illumination with a twilight sensor

Above, the scheme for installing a photorelay sensor for street lighting was described. But with what help does the photorelay determine the moment when it is necessary to close or open the electrical circuit? These devices use sensing elements made of different semiconductor metals, which are mounted at the place of the sensor where natural light falls. At the point of contact of these metals, a small electrical impulse arises, which gives a further command to close the entire circuit. Consider the main varieties of these elements (the principle of their work):

A visual step-by-step process of connecting a flashlight to a photo relay on a conventional stand

The wiring diagram for a light sensor for street lighting of a small area will be described below. To do this, we need a lamp, previously screwed into the cartridge, and the photo relay itself.

For greater clarity, we will install on the stand. To do this, we attach the light sensor and the lamp in the cartridge next to each other, which will symbolize the lamp.

Next, you should connect the zero and input phases to the light sensor itself (as a rule, the connection points are marked on the case).

By inserting special rubberized plugs into these holes, you can connect the wires. These rubber plugs protect well from dust and other harmful external influences.

"Expert Tip": The input wire connections should point downwards when mounting the sensor to increase protection against moisture and dust.

Before connecting, we clean the ends of the wires well (by about 1 cm).

1. input phase;
2. zero phase;
3. protective phase (grounding).

In a similar way, wires are connected to the lighting fixture itself. We bring the input and zero phases to the cartridge, and the ground phase is connected to the body of the device for lighting.

The last step will be to adjust the sensitivity of the regulator of our photosensor. This completes the installation process, it remains only to replace the protective cover and tighten the bolts.

This is how the whole procedure for connecting the light sensor and the lighting fixture to the electrical circuit looks like. It is not difficult, you just need to follow the correct order of connecting the wires. Otherwise, you can get negative consequences, up to a short circuit or even a fire.

The procedure for connecting a photorelay for street lighting to diode light sources or spotlights is similar to that described above and is not particularly difficult.

Technical data of twilight switches

The main parameters for the operation of the photorelay are prescribed in the GOSTs and the technical documentation of the devices. These indicators are selected taking into account the realities of use in our country, however, there are analogues of these light sensors on the market. Before purchasing the appliance, you should always make sure that the appliance will work correctly when connected to our electrical circuit.

The main characteristics of light sensors:

• the value of the rated supply voltage;
• power indicators of electrical energy consumption and the level of heat load on the lighting device;
• operating conditions in certain climatic zones (precipitation, dust, high or low ambient temperature, etc.);
• indicators of photosensitivity;
• varieties and types of devices (switched, luminescent and energy-saving).

Disadvantages of twilight switches

Along with the undeniable advantages, photo relays also have a number of significant disadvantages, which are also worth mentioning in this article.

Unlike a motion sensor, light sensors are not capable of illuminating a certain place at the right moment. The light lights up at once on all lighting fixtures, and lighting occurs in a not entirely rational way. Only one lamp can work or all at once at the same time.

These devices are very sensitive to external influences and weather conditions. Especially often they react negatively to ordinary dust. Also, the device may not work quite adequately in case of a sudden change in the weather, for example, with the influx of dark clouds, it may “think” that it is night and turn on the lights.

Photorelays with adjustable lighting level are distinguished by their high price tag relative to their counterparts.

Conclusion

Summing up this article, I would like to note the undeniable benefits of using light sensors. After carefully reading this text, you will find expert recommendations on how to connect the sensor to street lighting, how to properly configure the sensor, how to connect this device to a street lamp or a lamp in a stairwell, and much more. By installing this fixture on lighting fixtures, you can already begin to calculate profits.

The relative simplicity of the entire design of the photorelay and the rather simple installation process will not require special knowledge in the field of electrical engineering from a person. It is only necessary to have initial knowledge in this area, carefully study the instruction manual for the sensor, and you can safely install the photorelay with your own hands.

The extensive use of LED lighting devices in conjunction with a photocell gives a visible result in the field of cost savings, especially in areas that require a large area of ​​​​illumination. It is worth recalling that when choosing this kind of sensors and their subsequent purchase, you should carefully study all the data indicated on the package. Foreign analogues, which are now very numerous on the Russian market, may simply not be adapted to work in our electrical circuits.

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Each apartment or private house has rooms that do not require constant lighting. For example, in the corridors and on the stairs, light is needed only while people are here. Therefore, in order to save electricity, the owners install a motion and light sensor that breaks the supply circuit. Its influence extends to a certain zone, and at the beginning of any movement in it, the contacts close and the light turns on.

Principle of operation

The principle of operation of the sensor is quite simple. When a moving object enters the set zone, which is covered by the sensitivity of the device, it is triggered, followed by switching on the lighting. After the movement stops, the circuit is automatically opened and the lighting devices are turned off.

Most of these devices have a set viewing angle of 180 degrees. There are models that cover 360 degrees, used in large rooms.

Connecting a motion and lighting device to a circuit is as simple as it is. The main function is to close and open the electrical circuit with the connected lamps. Therefore, the connection diagrams of both devices are almost the same. The diagram is attached to each device in the form of instructions, and for the highest quality models from well-known manufacturers, the diagrams are applied to the case.

The rear cover of the sensor covers the terminal block along with the connection of the conductors. Stranded wires are recommended to be connected using insulated lugs NShVI. Two wires are used to supply power - phase and zero. Leaving the sensor, the phase is connected to the lamp, so when triggered, the contacts close and the current begins to flow to the incandescent lamp.

Classification

There are various types of sensors, each of which is best suited for certain operating conditions. For example, motion sensors installed outdoors have a high degree of enclosure protection with an IP rating of at least 55. IP22 or more is sufficient indoors.

In accordance with the type of power supply, the devices are classified into 220 volt connected to the mains and wireless, powered by batteries or batteries. The first group is considered the most popular and numerous, and the second is used mainly in conjunction with low-voltage lighting fixtures.

The main classification is methods that allow you to determine the beginning of movement in the controlled area. They are based on different detection principles:

• Acoustic devices that respond to noise. Belong to the category of passive equipment. They turn on when various sounds appear.
• Infrared motion and illumination devices. They work in the presence of thermal radiation emitted by warm-blooded creatures - people or animals. The reaction to animals often leads to false positives. These types of sensors are also passive switching equipment.
• The types of active devices include various types of microwave devices equipped with a sensor. They emit radiation in the microwave range and monitor their return. When a moving object enters the control zone, the changing waves give a command to operate or turn off the device. For security systems, devices with increased sensitivity are used, capable of detecting an object regardless of the presence of structural elements and other interference.
• Approximately according to a similar scheme, ultrasonic switching signaling devices work. They differ only in the range in which the waves are emitted. They are used very rarely and only in non-residential premises, or are used as an outdoor device.
• The most expensive and effective are combined devices that combine various methods of fixing movement. This design prevents false alarms, increasing the reliability of tracking systems.

Basic parameters of sensors

Having decided on the design, it is necessary to make the right choice of parameters and technical characteristics of these devices.

An important indicator is the viewing angle, which can range from 90 to 360 degrees horizontally. This indicator is selected based on the number of directions in which it is possible to approach the desired point. If the sensor is mounted on a wall, 180 degrees is enough, and when attached to a pole, 360 degrees will be required. In the interior, narrowly focused devices can be dispensed with, and if there are several doors, devices with advanced functions will be required. These models are expensive, so the choice should be guided by specific operating conditions.

There is also a vertical viewing angle, which is about 15-20 degrees for cheap devices. Expensive devices can work in the vertical range up to 180 degrees. Such devices are used in security systems, since they are not economically feasible for adjusting the light. They are installed at the optimum height to avoid the so-called dead space.

An important role is played by the distance at which the device is considered the most effective. Indoors, 5-7 meters is enough. The outdoor sensor can have a long action length, which depends on the area of ​​the controlled zone. However, if this indicator turns out to be too high, the number of incorrect or false positives may increase.

The power factor of the lighting fixtures connected to this circuit should also be taken into account. All types of motion sensors correspond to a certain load and current strength with a set rating. Therefore, when choosing a particular device, you need to take into account the total power of the lamps installed in chandeliers, ceiling lamps, etc.

Additional selection criteria

In addition to the main parameters, there are other criteria that at a certain time may become decisive.

Motion and light sensors are selected according to the place of installation and the method of fastening. They can be mounted on walls or ceilings and mounted on a bracket, as provided for cabinet models. All concealed installation options are provided by miniature built-in devices mounted in special recesses in inconspicuous places.

Some sensors have additional features. Their capabilities are significantly expanded due to the built-in light sensor in one housing. When the device is installed on the street or near a window, then in the daytime its operation is not required, since there is already enough light. The photorelay can be connected separately or included in the design of the motion sensor.

A useful feature is protection from pets - dogs, cats and others. In its presence, false positives occur much less frequently. The same can be said about the blackout delay. In many cases, the light is turned off immediately after the object leaves the device's coverage area. This is not always convenient, since lighting is still needed. Therefore, the most convenient models are considered not only with a delay, but also with the possibility of its adjustment.

After acquiring a sensor to turn on the light, it must be placed correctly, thereby ensuring its correct operation. In this regard, it is necessary to comply with the established rules and regulations:

• Lighting devices should not be located near the sensor.
• The same applies to air conditioners and heating systems, since the sensor may react to air currents.
• Too high installation height expands the control zone, but at the same time the device loses its sensitivity.
• On the way of the sensor there should not be large objects obscuring a large area.
• In rooms with large areas, motion sensors are recommended to be placed on the ceiling. The field of view of such devices should be 360 ​​degrees. If it is necessary to turn on the lighting, it is installed in the center, providing a minimum number of dead zones.

How to connect

In the simplest version, the sensor is connected to a break in the phase conductor, which is supplied directly to the lamp. This method works great in completely dark rooms where there is not a single window.

In this case, the phase and zero conductors are brought into the sensor from the input side and connected to the corresponding terminals L and N. At the output, the phase wire goes further to the incandescent lamp, and the neutral conductor is connected to the nearest zero of the electrical circuit.

When using a sensor to turn on the light on the street, you will additionally need a light sensor that works in automatic mode. Instead, a separate switch can be installed on the line, which can be turned on and off manually. In this way, unnecessary switching on of the light in the presence of normal daylight is prevented.

Similar additional combining devices are also installed in a phase break. If a photorelay is used, it must be installed in front of the motion sensor. Due to this, the power supply to the device will be supplied only after dark, and during the day it is in the off state. The service life of the motion sensor is significantly increased, since its resource is limited to a certain number of operations.

A significant drawback of these schemes is the impossibility of long-term use of the included lighting. The light will immediately disappear after the motion stops. This can be avoided by connecting in parallel with the conventional switch detector. When it is in the off position, the sensor will work. After switching on, the sensor stops working and the light is on for the entire time until the circuit is interrupted by the switch.

Settings and adjustments

The correct operation of the sensor to turn on the light largely depends on its settings.

In order for it to function correctly, you must perform the following steps:

• Time setting (TIME). Sets the time interval during which the light will be on from the moment of the last detected movement. This value can be set in the range of 1-600 seconds. For these purposes, the regulator is set to the desired position, in the direction of increasing or decreasing.
• Trigger setting according to light level (LUX). Ensures correct operation of the sensor during daylight hours. The response threshold is set independently using another adjusting knob. As a rule, the most optimal value is selected experimentally.
• Sensitivity to actuation (SENS). Provides the desired response of the sensor in the presence of movement. If there are too many operations, it is recommended to reduce the sensitivity of the device.