Light sensor LXP-02 and LXP-03. Installation
In this article we will consider the issues of installing and connecting a light sensor. Also given electrical circuits the most popular models of light sensors.
Let me remind you that this device is widely used in the field of home automation for turning on/off electric lighting depending on the light level outside. The names may be different - light sensor, light sensor, light control switch or photo relay, but the essence is the same.
I spoke in detail about such a sensor in the first part of the article -. Its structure, operation and characteristics are discussed in detail there.
Therefore, I’ll get straight to the point:
I will give three options for the connection diagram, they are all identical, the only difference is in the display method.
The connection diagram for the light sensor is completely identical to. Only the “filling” of the sensors differs.
The diagram is taken from the article about the motion sensor, link above.
This is how the light sensor connection diagram is shown in the instructions:
Light sensor LXP. Connection diagram from the instructions
For those who like everything to be “at their fingertips,” here is the following picture:
A short explanation of the connection diagrams:
It is worth adding that light sensors can be connected in the same way as conventional switches - in series and in parallel, if necessary. An example can be seen in the article about.
So, we figured out the connection, now
It would seem, what is so wise here? I screwed it on (see the picture at the beginning of the article), connected it, configured it, and that’s it! But sometimes the installation location is chosen poorly, and problems begin.
On our street at one time the street lights turned on in an intricate way in the evening. They will turn on, go out, turn on again, and so on with a period of about 1 minute. Then, with the onset of good darkness, they turned on completely.
Why is that? The light sensor was simply mistakenly installed in the illumination zone of the flashlight being turned on. It turns out: it became dark - the sensor worked - the flashlight came on - it became light - the sensor turned off - it became dark... And so on, a vicious circle.
When setting up the light sensor, it is important to use the black bag that comes with the sensor. This bag serves to simulate night.
Bag for setting up the light sensor
Of the adjustment controls in the light sensor, there is only a light level control (LUX). It sets the level at which the sensor's internal relay is triggered.
The level setting is described in more detail in the description. schematic diagram, below.
There are the simplest light sensors (for example, LXP-01), which have no adjustments at all. There are advanced ones that also have an on/off delay time regulator.
Well, now the most interesting thing -
Undoubtedly, to quickly and easily repair a light sensor, you need its diagram, from which it will immediately become clear what is connected where and how it works. Below are a couple of sensor diagrams and repair recommendations. If you have questions about repairs, ask in the comments.
The circuit is copied exactly from the board shown in the link at the beginning of the article. It is worth noting that the manufacturer is constantly working to improve its device (price/quality), so the scheme may change.
Light sensor LXP-02. Electrical circuit diagram
But the principle remains the same:
The supply voltage of 220 Volts is supplied through terminals L (phase) and N (zero).
Phase and zero can be “confused”, just as in principle it is possible (but not recommended) to turn off the zero and not the phase in conventional switches. Only safety and common sense suffer.
The voltage is rectified by a diode bridge (4 diodes of type 1N4007), filtered (smoothed) by an electrolytic capacitor, and stabilized at a level of +22...24 Volts by a zener diode of type 1N4748.
Next, the constant voltage powers the rest of the circuit, which works like this. At the output of the 68k resistive divider - VR - Photoresistor, a voltage is generated that is inversely proportional to the illumination. Trimmer resistor VR with a resistance of 1 MOhm is the same “twist” with which the desired response level is set.
It is not a fact that a photoresistor is installed in such circuits; a photodiode may also be installed, but the principle is the same.
If you want to save energy, set the maximum resistance, turn it clockwise ( LUX-), and it will work when it is already completely dark.
If you want the street lighting to turn on at the slightest cloud, turn the regulator in the other direction ( LUX+).
When darkness sets in, the illumination drops, the resistance of the photoresistor increases, and the voltage at the base of the transistor increases. And it reaches such a level that the transistor opens, a current sufficient to turn on the relay flows through the collector CA. The relay with its contacts turns on the load, which is connected through the output LOAD.
At the same time, the LED lights up, and a 47 uF capacitor in the base circuit smoothes out all processes so that the relay does not click too quickly, for example, if it is blocked by a tree branch swaying in the wind.
In conclusion, here is a diagram of a more powerful model, LXP-03:
Twilight switch, lighting (light) sensors are a device for automatically controlling sources of artificial (electric) light. Depending on the degree of illumination of the surrounding space, the sensor is capable of sending a signal to turn on/off lamps, spotlights, lanterns and other lighting devices. Properly installed and programmed equipment operates without human intervention. In other words, the light sensor (twilight relay) is circuit breaker, which monitors and controls the brightness of lighting in a certain area or room. When twilight occurs, it will turn on the light, and after sunrise, it will turn off. Using of this equipment You can achieve energy savings of up to 10-15%.
Design, installation and principle of operation of the light sensor
The main area of application of light sensors is automatic light control. They are used to automate lighting in garages, entrances of residential buildings, on highways, garden areas private cottages and other places where during the day the space is illuminated by natural light, and at dusk - by electric light.
The principle of operation of light sensors is to monitor the level of light radiation entering the field of “visibility” of the device. The light rays are focused by a photocell (light relay) and directed to 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 lock electrical devices. It is this signal, obtained as a result of the voltage created, that turns on the lamp when dusk occurs, and with the onset of dawn, turns it off. In order to save money at night, it is possible to turn off the sensor for a certain time.
Thus, any lighting sensor (street, home) is a photosensor - a primary transducer, 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 lighting differ in several respects:
In some cases, to control the lamps, the connection of a motion sensor for lighting, which reacts to the presence of a person, is also used.
Currently, 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.
According to the operating principle, The light sensor is designed like this: a photosensitive element that is installed in the sensors is capable of changing its resistance depending on the lighting. This element is usually a photoresistor.
Then, a calibration circuit comes into effect, through which the signal from the photoresistor passes to the transistor.
There is a relay in the transistor circuit. The transistor, with the help of a relay, closes the network and the lamp or spotlight, which is connected to the network, begins to glow. In the article, the principle of operation will be described in more detail.
It is worth noting that the connection diagram for the light sensor is identical to the connection diagram for the motion sensor.
Of course, it’s not difficult to connect and set up; it’s much more difficult to determine the correct location for installing the sensor. An acquaintance told me a story about how a street light in his neighborhood kept turning on and off.
And after it was completely dark outside, he finally began to work normally. Do you know what was the matter?
The light sensor was installed directly under the lamp. Because of this, when darkness fell, he turned on the flashlight, recognized that it was light and turned it off. Similar situation can happen to everyone. But to prevent this from happening, you must not install light sensors near the light source.
When you calibrate the sensor, use the black bag that comes with the kit.
The only thing that can be adjusted with this sensor is the dimmer. They can set the level when the relay will operate. Details of adjustment and setting are described below.
The light sensor LXP-01 can be classified as the simplest. It does not allow you to change or configure anything in it. There are more advanced sensors, in which you can adjust the response delay.
Sensor LXP-02.
Sensor output assignments:
1. Red is needed to supply the load
2. Blue, maybe green, is zero
3. Brown (black) - power sensor.
If you remove the white case, then under it we will see the sensor circuit located on the printed circuit board.
To easily calculate the required number of lamps, use Calculator for calculating the number of lamps.
The sensor contains a DE3F-N-A 24 VDC relay. Contact current 10A. This value determines maximum load, which the sensor is capable of. That is, 10 by 220 will be 2.2 kW. Exactly the same as stated in the instructions.
But my opinion: you should not connect more than 4 amperes to this sensor. Everything above is only possible through an intermediate starter.
These are the tracks, with a layer of solder on them, they are the ones that burn more often than others when there is an overload, an incorrectly connected K3. If this happens, then the relay will have to be replaced.
According to the instructions, the LXP-03 light sensor is able to switch currents of 25A. The board indicates that the relay current is 30A, most likely the manufacturers decided to play it safe, and in this regard, I was not far from them. I decided to limit the current to 16A.
For lighting, this is also with a reserve.
And for dessert - all the fun stuff:
The presented diagram is taken exactly from the board that is shown at the beginning of the article. The manufacturer is currently actively improving and changing its device, so some data may change.
In principle, everything is the same:
The 220V supply voltage is supplied through the zero and terminals. Zero - N, terminals - L.
If you swap the phase and zero, or even turn off the zero and not the phases, then nothing bad will happen. But doing this is highly not recommended; no one has yet canceled security.
The voltage is rectified using a diode bridge, 4 diodes of type 1N4007. An electrolytic capacitor is responsible for filtering the voltage; stabilization occurs at the level of +22...24V; for this, a zener diode of type 1N4748 is installed.
The rest of the circuit is powered by DC voltage. It is arranged as follows: At the output of the resistive divider 68k - VR - Photoresistor, a voltage is created that is completely inversely identical to the lighting level. The device that adjusts the response level is a trimming resistor VR with a resistance of 1 MOhm.
What exactly is installed in such circuits: a photoresistor or a photodiode is unknown. Most likely a photoresistor, but a similar photodiode could also be there.
If you want to use electricity economically and efficiently, then turn the controller clockwise to the maximum, so the light sensor will only work when it is completely dark. Turning the regulator to reverse side, then be prepared for the fact that the light will turn on even during the day if a large cloud hangs over you.
Here's how the process of turning off the light when darkness sets in: the lighting level drops, the resistance of the photoresistors begins to increase, and the voltage at the base of the transistor increases. When the voltage reaches a certain level, the transistor opens and a current begins to flow through the collector, which activates relay K1. The relay contacts turn on the load. The load is connected via the LOAD pin.
The LED lights up to indicate the operating status. To prevent the relay from switching the sensor too often, for example, from a swaying tree branch, a 47 µF capacitor is installed in the circuit, which smoothes out all processes.
More powerful light sensor circuit LXP-03:
It is identical to the first diagram in the article, I will list the differences:
1. The power circuit is able to limit the voltage in the phase circuit.
2. There is a diode bridge with filters. The same as in the previous diagram, I just didn’t depict it very well.
3. Instead of one zener diode, as in the first diagram, here there are two of them installed in series. Moreover, the voltage remained the same - +24V.
4. A more powerful relay is installed here, with a correspondingly more powerful coil current. Also, a composite circuit with two complementary transistors is used here.
If you know how the circuit works, it will be easy to repair.
Owners of their own homes often think about which light sensor to choose for street lighting. It’s very convenient when the light automatically turns on in the dark and turns off in the light. There are 2 options for this: install a photo relay or an astro-timer. Since the first device is more common due to its low price and availability, we will consider it first.
In this article:
This device has different names. For example, photocell, light sensor, photosensor or photosensor, light sensor. However, the most common name is “photo relay”. With its help, you can automatically turn on the light in the dark and turn it off in the light.
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 power supply to the lamps begins. Accordingly, as illumination increases, 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. IP44 can be considered the minimum. The higher the class, the better. This protection marking means that objects smaller than 1 mm in size will not fall into the lamp, and it is reliably protected from rain. It is also worth paying attention to temperature regime operation exceeded 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 snow falls. The light sensor can perceive the reflected light as dawn and will turn the lamps on and off. It is worth paying attention to the presence of a response delay. By setting it for 5-7 seconds, you will prevent a power outage when light hits the sensor, for example, from car headlights.
A correctly selected location for the device will ensure its correct functioning. The following must be taken into account:
To summarize, we can say that choosing a location is not the easiest thing. Sometimes you need to change it several times to find it 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; it is inconvenient to climb onto a pole each time to do 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 connection of the wires takes place 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. It is better to connect a powerful backlight 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. The motion sensor can also be used to adjust the activation delay so that it is not triggered by the movement of a branch or a bird flying past.
A photo relay from any manufacturer has 3 wires for connection - 1 is always red, the other 2 can 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 the instructions to see which wire should be connected where.
Light sensitivity is adjusted by rotating a small plastic dial on the bottom of the relay. There are always indicators next to it to indicate 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 tightened until the relay starts working. The setup is complete when the light comes on.
Despite the fact that the sensors are designed to turn on and off automatically, they have a special toggle switch or button that allows manual control of the device.
This device is inherently different from a photo relay. Automatic switching on of lighting occurs at a specified time. The astro timer is programmed with the times when it gets dark and light in different regions. And he makes adjustments using GPS. You just need to enter the coordinates of its location, the current date and time. Based on the entered data, he selects suitable program and working.
This device has a number of advantages over photo relays. 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 lighting on and off by 2-4 hours. Its only drawback is the high price.
If you are choosing a device to illuminate streets or places where people stay for a short time (gate, toilet, etc.), a photo relay is suitable. But if there is no desire to depend on weather conditions and care for the photocell, then it is worth choosing the optimal astro-timer model for certain conditions and needs.
Sensors for automatic lighting control can be classified according to the type of response:
From the above review, the following conclusions can be drawn:
To solve the problem with automatic turning on and off of the light, you need to decide whether the light should be constantly on in the dark or should turn on and off in the dark when a person or other object appears.
Sensors of the same type may have different principle work, on which the accuracy of its operation depends. Let's take a closer look at them.
Light sensors, or photo relays as they are also called, were found wide application in the field of outdoor lighting control. For example, where it is desirable for the light to be on constantly. The principle of their operation is based on the fact that the photosensitive element changes its conductivity depending on the degree of illumination. The following elements are used as such an element:
All three types of photosensitive elements have in common the fact that their conductivity increases with illumination. In simple terms, they conduct current when light hits them. The only difference is the sensitivity. The signal from the light sensor comes to the amplifier, which in turn controls a power switching device - an electromagnetic relay or triac. In cheap small-sized devices, 1 transistor is used as an amplifier. And in expensive ones - microcircuits.
Most often they are called “photo relay” or “twilight switch”. Common models of these sensors are labeled as FR-601, FR-01, etc.
Based on their design, photo relays are produced in three types:
In order to form a directional field of view, Fresnel lenses are used. They are applied on one plate, which is easy to notice if you look at appearance such a device. The number of lenses in a multilens can vary from 20 to 60 pieces, in some cases more.
Sensors with a circular field of view contain several sensitive elements and a multi-lens in the shape of a dome or its sector.
Advantages of IR sensors:
Disadvantages of IR sensors:
4.2 Ultrasonic and microwave motion sensors
The operating principle of ultrasonic sensors is based on the Doppler effect. This is a phenomenon in which a wave changes its length as the emitter or receiver moves. Such devices consist of two elements - an emitter and a receiver. They are fixedly fixed to the wall or ceiling.
In a normal state, when nothing in the field of action moves, the sent and received reflected waves are the same; when movements occur, the waves change. The signal receiving circuit of the ultrasonic sensor reacts to this, after which the actuator (power) element - a relay or triac - is turned on.
By the way, some birds and animals navigate in space in the same way, for example, the bats. In technology, the same principle is used to detect obstacles when moving cars (parking sensors system) and other mechanisms.
Important! Please note that animals react to ultrasound, so if your cat or dog begins to behave abnormally after installing such a device, simply change it to an IR sensor, for example.
Advantages of ultrasonic sensors:
Disadvantages of ultrasonic sensors:
4.3 Microwave (radio wave) sensors
Microwave or, as they are also called, radio wave sensors operate on the same principle - there is a receiver and an emitter (usually they have one common antenna), which respond to changes in the nature of the waves. Only in this case, not sound, but radio waves are used. You can see their operating principle in the figure below.
Unlike ultrasonic ones, microwave motion sensors do not irritate animals. At the same time, they can detect movements through walls and doors, which can be both useful and harmful in operation. There is also an opinion that electromagnetic high-frequency radiation can be harmful to living organisms.
As you can guess from the name, acoustic sensors react to the appearance of noises and sounds. The closest device to them is a cotton light switch. The only difference from the latter is greater sensitivity and a wider range of settings. Most often found as part of combined devices, working in tandem with a photo relay - the so-called flash noise or photoacoustic sensor (switch). Separately, acoustic sensors are often used not in lighting control circuits, but in security systems.
Example of a photoacoustic switch (PAS):
Photo relay connection diagrams:
Color markings of wires and diagrams may vary slightly, so check the instructions for your specific model. To force the light to turn on or off, the circuit can be supplemented as shown in the figures below.
With this scheme, a photo relay controls the lighting, but it is possible to force the lighting to be turned on with a switch regardless of the light level.
A scheme can also be used in which the switch is able to forcibly turn off the lighting, even in low light conditions:
If the lighting load exceeds rated current relay, you can use the lighting connection diagram via .
With this scheme, the photo relay does not control lighting fixtures, but by a contactor, and it, in turn, turns the lighting on and off, so the load current passes not through the contacts of the photo relay, but through the contacts of the contactor.
Note: The figure shows an example for a three-phase circuit; for a single-phase circuit, connect in the same way, the only difference will be that there will be 2 wires in the power circuit, not 4.
As mentioned above, there are photo relays for installation in an electrical panel on a DIN rail with an external light-sensitive sensor. Their connection diagram is somewhat different, but in general there are no special differences. Your device may have other terminal assignments; check this in the manufacturer's data sheet.
To turn on the light in the evening and stay on until the morning, use light sensors (photo or twilight relay). If you need the light to turn on only when you approach the door or enter the room, use one or more motion sensors of any type or acoustic (light and noise) sensors. They are connected, for the most part, similarly to a photo relay.
Connection diagrams for motion sensors and photoacoustic (light noise) sensors:
With this scheme, the lighting is controlled only by a motion sensor. You can also use circuits with a switch:
In case you need the light to turn on when you want it small room With different doors(for example, a corridor or hallway) - the most optimal would be to install two IR motion sensors in opposite corners or on the walls:
To prevent the motion sensor from turning on the light during the day, either connect it in series with the switch, or use it in conjunction with a twilight relay. Combined light sensors have been developed for the same purposes.
Such devices combine a photo relay and an IR motion sensor. A striking example is light-noise sensors - they are used together or as part of lamps for housing and communal services. They are often installed in entrances and other in public places, you can see an example of such a lamp in the figure below.
