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Technologies in the modern world are constantly evolving. One of the latest discoveries has been improved developments in the field of outdoor lighting. In addition to economical and bright LED lamps, an important achievement is the photo relay for street lighting. The latest technology is classified as intelligent, since the lamps, thanks to special software, light up and go out without human intervention. The article will tell you in detail about the device.
A photo relay is a device for adjusting and turning on street lighting
Photo relay, or street light sensor to turn on the light
A photo relay is a device for regulating street lighting. It is used in different places to save energy. The principle of operation of the relay, which is based on the photoelectric effect, is that when there is a small number of light rays, the contacts close. As a result, the street sensor is turned on. When the lighting increases to the required level, the contacts automatically open and, accordingly, the lamps turn off.
Photo relays are used in different places to save energy
The device has many names and definitions. In some technical textbooks it is called a light-control switch, in other publications it is called a light-sensitive switch. In informal vocabulary you can most often hear the phrase “light sensor” or “light sensor”, “photo sensor”. There are also simpler names, such as “twilight sensor” or “day/night switch”. All these are names of the same item, which in industrial production is called a photo relay.
Photo relays are installed at the entrances to houses, in the territories of administrative buildings, in the entrances of apartment buildings, and on power poles. Thus, entrances to premises, streets and roads will be constantly illuminated at dusk. With such a device, forced switching on and off of lamps and street lighting lamps on poles will not be required. This will happen automatically, and energy costs will be significantly reduced.
Operating principle and design of a light sensor for street lighting
The photo relay is based on a photoresistor or phototransistor, which changes its parameters with a certain change in illumination. If there is enough light falling on them, then the power supply circuit is open. With the gradual onset of darkness, the photocell begins to react, and at a certain reading specified in the settings, the circuit is closed. The process can occur not only in the evening, but also, for example, in very cloudy weather. When the lighting improves, that is, morning comes (or the clouds and fog clear), the circuit opens.
Main unit and remote photo relay sensor for street lighting
Interesting to know! The photo relay device is considered universal, and it can be used for other purposes, for example, for irrigating lawns. To do this, the device is connected to the irrigation system and, thus, the lawn or flower bed will be moistened every night.
When installing street lighting, you need to decide what technical characteristics the photo relay should have. Based on this principle, two types of devices are distinguished:
- photo relay with remote sensor;
- device with a built-in light sensor.
The remote sensor device is small in size, it is easier to provide protection from external negative influences and illumination. This device can be placed autonomously, for example, in an electrical room. An example of such photo relays are models for DIN rail. The built-in sensor should be located in close proximity to the lighting device, for example, next to lamps - on street lighting poles. In this case, it is very important to choose a place so that the lamp light does not fall on the photosensor. This option is most often used when installing solar-powered street lighting.
When installing street lighting, you need to decide what technical characteristics the photo relay should have
Performance characteristics of the street light sensor
Having chosen the desired type of sensor, you need to determine the technical parameters of the device. The main ones, which directly affect the quality of work and service life of the photo relay, are the following:
- Mains voltage. It can be 220 or 12 V - the choice depends on the voltage providing street lighting. Twelve-volt light sensors are most often used for battery-powered lighting.
- Operating mode. It is necessary for the photo relay to operate under significant temperature changes, which depends on the climatic conditions in a particular region. Ideally, the device should withstand extreme heat and severe frost.
- Housing protection class. For installing street lighting, IP44 or higher level is suitable, ensuring protection of the device from splashing water, dirt and solid particles with a diameter greater than 1 mm. If we are talking about installing a photo relay indoors, then a protection level starting from IP23 is suitable.
- Power. The operation of any relay is designed for a certain voltage level of the power load, and the total power of all connected devices must be 20% less than the permissible norm. In this way, it will be possible to reduce the wear of devices and extend their service life.
The photo relay operates under significant temperature changes, regardless of climatic conditions
This is a basic, but not final list of photo relay characteristics that must be taken into account when choosing a sensor. A competent approach in this matter will have a positive impact on the performance of the device and extend its service life.
Helpful advice! One of the main conditions for the uninterrupted operation of a photo relay is the presence of a stable voltage in the network, which should be 30% higher than the given indicator of the device itself.
Light sensor connection settings options
Almost all devices have an automatic adjustment system that allows you to select a specific operating mode. The peculiarity of this element of the device is that it has to be configured manually. To do this, turn the special knob in the desired direction and select the required option.
Photo relay is used to automate the street lighting system and at the same time save energy
The photo relay can include the following setting controls:
- Response threshold. This setting allows you to increase or decrease the sensitivity of the device. It is recommended to lower its level in winter, especially in snowy weather, to avoid unnecessary reflection of light from the snow, as well as in places with bright street lighting, for example, in megacities.
- A second delay to turn the device on or off. If you increase the turn-off delay, you will be able to avoid false alarms that occur when a random beam hits the photo relay, for example, light from car headlights. Delaying the switch on will prevent the device from reacting to a momentary darkening of the device, for example, from a cloud or the shadows of flying birds.
- Light range control. When connecting a photo relay, using this setting, you can provide the required level of illumination. At its lower limit, the sensor is activated, turning on the power supply, and, conversely, at its upper limit it turns it off. The range can vary from 2 to 100 lux (2 lux – pitch darkness) or from 20 to 80 lux (in this case, 20 lux – deep twilight, when the outlines of objects are barely visible).
Mastering and effectively using the listed settings will help ensure the most optimal operation of the photo relay, eliminating false alarms, thereby making the lighting more comfortable and energy consumption as economical as possible.
The photo relay can include many regulatory settings
Typical photo relay malfunctions
Failures in the use of photo relays are most often caused by their incorrect selection and/or operation. The most common failures are exceeding the resource, but a number of other reasons can be listed:
- Exceeding the permissible current and/or voltage.
- Failures related to cycle time (especially when the relay switches at very low signal levels or when the relay does not operate very often, causing the contacts to oxidize).
- Contamination of the working surface of photo sensors (especially typical for photo relays that serve industrial equipment).
- Poor ventilation of relay panels, which causes overheating of MOSFET transistors.
With proper routine maintenance, all of these problems can be prevented. The service life of the relay and its rated power are always indicated by the manufacturer. These parameters are determined for photorelay operation under low level switching conditions and correspond to the minimum number of operations that can be expected without mechanical failure due to contact wear.
It is much more informative when the developer indicates in the operating instructions the service life of the relay under conditions of hot load switching, when the current and voltage values are maximum (at the rated power of the device). In these cases, the relay fails due to contamination of the contact material, when current and voltage have to be increased to operate: this is accompanied by a sharp increase in resistance during the passage of the control signal. Therefore, light-receiving surfaces should be cleaned as often as possible, using chemically neutral cleaners for these purposes.
When used intensively, photorelay sensors never operate longer than indicated in their technical specifications. Even in low-signal applications, faults in the testing devices can cause device failures. As a result, inrush currents caused by capacitive loads, hot switching and voltage surges accelerate their aging.
Selecting the optimal location for the street lighting sensor
Before connecting the light sensor, you need to decide on its installation location, taking into account a number of important points:
- if the photo sensor is of a remote type, then its location should be in direct reach of daylight;
- sources of artificial lighting should be located as far as possible from the sensor, the main thing is that the relay does not react to their turning on or off;
- It is advisable to exclude as much light from car headlights as possible.
The optimal height for installing the photo relay is from 180 to 200 cm, which will provide the ability to adjust parameters while standing on the ground, without using stools and stepladders.
Some tricks will help you fulfill the above requirements. For example, you can protect the photo sensor from light from street lights using a large-diameter piece of black plastic pipe 15-20 centimeters long. For this purpose, it is necessary to cut the pipe at the bottom at an angle of 40-30° from the vertical wall so that it looks up.
The installation location of the photo relay is selected taking into account a number of rules
Helpful advice! In order to standardize the assembly of devices, special symbols and terms were invented to indicate photo relays on diagrams and drawings. Those who decide to install the device themselves need to know them.
If the relay is designed for one lamp, but of high power, then the ideal place would be to place it directly behind the lampshade. This is where the least amount of random light will fall. It is much easier to configure the sensor if it is located on the east or west side of the building. The main condition for this is the absence of objects with bright light nearby. Therefore, in this case, you need to choose the side where “exposure” is eliminated as much as possible.
DIY relay installation
At first glance, after purchasing a light sensor, there should be no problems installing it. And this is true, it is only important to know some installation features that will help you correctly place and install the photo relay on the street lamp.
Installing the device does not require calling an electrician and can be done easily with your own hands, even if you have no experience working with electricity. First of all, before purchasing a product, you need to decide where the device will be placed.
There are various types of brackets with which a photo relay is mounted to a lamp or other surface. These fasteners include:
- eyes for fastening with self-tapping screws or on a mast (photo relay “Day-Night”);
- DIN rail for mounting on a special lamp bracket (FR-601).
Features of photo relay placement:
- Secure the product using its standard brackets. It is not permitted to drill additional holes in the product body or perform similar actions.
- Install the sensor with the base facing down, and never the other way around.
- Do not place the device near chemically active environments or flammable materials.
- Place the photo relay so that there are no barriers to sunlight. This will affect its functioning.
- Do not install the product in a location where it will be exposed to light from a lamp.
- When placing on a street lamp, consider the degree of protection of the photo relay.
When carrying out installation work, make sure that the supply voltage is removed from the lamp.
Photo relay for street lighting: equipped with additional functions
Both types of photo relays, both with a built-in and remote sensor, have their own varieties. The classification of devices is based primarily on their purpose and additional functional equipment. Both types of devices have subtypes.
Photo relay with motion sensor. Such a device is installed where lighting is required only during human presence, for example, in corridors, in the courtyard of a country house or in a garage. The device responds to movement and heat emitted by the human body.
A photo relay with a motion sensor is installed where lighting is required only during human presence
Photo relay with timer. This option is used when illumination is needed for a certain period of time. Users of the device set the desired time when it turns on or off. Accordingly, the device is equipped with a timer for turning the light on and off. Such sensors are especially relevant in decorative lighting of personal plots or buildings.
An astro timer is not just a photo relay, but a more advanced device programmed for sunrise or sunset in different climatic zones. It is enough to select a specific time zone in memory. The device will automatically operate at the time specified by the program. The price of a photo relay with an astro-timer is much higher, but there is no need to worry about the installation location.
Devices with additional functions are not popular, since the price of a photo relay for street lighting with built-in sensors can be twice as high as the cost of a conventional light-responsive device. Therefore, to provide additional functions, it is not at all necessary to purchase an expensive multiphoto relay; it is enough to buy a regular device and additionally install motion sensors or timers.
An astro timer is a more advanced device programmed for sunrise or sunset
Application
The main mission of the photo relay is to make human life easier. It’s not a royal thing to turn on the light with your own hands, so the devices take on this responsibility. They can be found everywhere: on the street, in residential and office premises. Photosensitive relays are most widely used in street lighting control circuits. They can be trusted with both lanterns and decorative and architectural lighting, lighting of courtyards, parking lots, parking areas, and viewing areas of CCTV cameras.
Photo relays help save on electricity. They have not yet learned how to produce it, but they can reduce consumption. Under the control of the devices, the lamps light up only when it is really dark and do not consume electricity in the morning and during the day if the operator missed the time to turn off the lights.
Connection diagrams for photo relays for street lighting
The main function of the photo relay is to supply power at nightfall and turn it off at dawn. Thus, it is an automatic switch that operates without human intervention. The role of the shutdown button is played by a photosensitive element. The photo relay connection diagram is similar: a phase is supplied to the device, it is interrupted at the outputs, and if necessary, the circuit is closed, as a result of which voltage is supplied to the lamps or spotlights.
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To ensure the operation of the photo relay, power is also required, so a zero is connected to certain contacts. Since the lighting is supposed to be in an open area, there is a need for a ground connection.
It is important to correctly connect the conductors coming out of the body of the regulator itself with the lamp and the network
Helpful advice! To provide additional functions, you can purchase photo relays with motion sensors or timers. However, two separate sensors, for example, for light and motion, will be cheaper to purchase and maintain. In addition, it will be easier to replace a part in one of the two devices than to repair the entire photo relay as a whole.
Unfortunately, there is no universal connection diagram that would fit all types of photo relays, but certain points are typical for all operations. They must be taken into account, especially if you install a photo relay with your own hands.
In almost all models, the output relay has three multi-colored wires that correspond to the following designations:
- black – phase;
- green – zero;
- red – phase commutating to the light source.
To provide additional functions, you can purchase photo relays with motion sensors or timers
Step-by-step instructions for connecting photo relays for street lighting
The instructions below will tell you how to connect the photo relay step by step, quickly and correctly:
- Pre-installation of the distribution panel. It is usually mounted on the wall, and conductors are connected in it.
- Connecting the photo relay according to the diagram, which is in the technical documentation attached to the device itself. Usually a bracket is used as a fastener. It is installed in a place where the relay will receive direct sunlight, but other light sources are isolated.
- Adjusting the system using a controller, that is, selecting the parameters for the device’s response to specific conditions of lighting changes.
- The regulator is installed on the external part of the device with the corresponding technical characteristics: sensitivity range – 5-10 lm; power – 1-3 kW, permissible current threshold – 10A.
If the device is mounted in the middle of an electrical panel with a complex design, where the sun's rays do not penetrate, then the relay and switch are installed separately from each other. The parts of the device are connected to each other with special cables.
The photo relay is connected according to the diagram, which is in the technical documentation attached to the device itself
When installing street lighting, it is recommended to follow the following rules:
- It is better to place a device with an external photocell in such a way as to exclude direct light from the installed lamp. Otherwise, the device will work with errors.
- To check whether the circuit is connected correctly or not, you need to connect the starter to the mains. The result will be clear when the lamp is activated.
Nuances in light sensor connection diagrams
The fact that the photo relay is selected taking into account the expected load may affect the cost of the product: depending on the power, the price increases. Therefore, in order to save money, it is possible to provide power supply not through a photosensor, but through a magnetic starter. This is a special device designed for frequent on/off operation. Using a trigger mechanism allows you to connect power using a photosensitive element with minimal load.
Thus, in fact, only the magnetic starter is turned on, so only the power consumed by it is taken into account. But at the terminals of the magnetic starter it is possible to use a more powerful load.
In order to save money, you can provide power supply not through a photosensor, but through a magnetic starter
Helpful advice! Before installing and configuring the device, it is recommended to carefully study the lighting connection diagram that comes with the device. The document clearly and clearly shows all the wires of the photo relay, and also shows where they need to be connected.
In the case when, in addition to the day/night sensor, it is necessary to connect devices with additional functions, for example, a timer or motion sensor, they are installed after installing the photo relay. In this case, the order of priority of additional devices is unimportant.
If a timer or motion sensor function is provided in the structure of the device, but it is not needed in a particular case, then these devices are simply excluded from the general circuit, that is, no wires are connected to them. In this case, if necessary, these elements of the device can be connected.
Device customization options
Modern photo relays for street lighting have functionality that allows you to extremely accurately adjust the operating mode in specific conditions. You can change the specified settings yourself without resorting to the help of specialists. To do this, simply turn the regulator to the desired position. Basically, the following adjustments are applied:
- Changing the response threshold by adjusting the sensitivity. The need for this function is due to the fact that there is different illumination outside depending on the time of year. For example, in winter there is more light due to its reflection from the snow, so it is necessary to set the sensor sensitivity to a lower level. In addition, a lower response threshold is set on photo relays that are installed in cities, at a relatively close distance from large light sources.
- Turn off and on delay. As already mentioned, this protects the device from turning off when light falls from extraneous sources. The switch-on delay is important so that the relay does not turn on the light when it falls into the shadow of a cloud passing across the sky or a flying bird.
- The illuminance range determines the conditions under which the photosensor keeps the power circuit open. The lower limit can be set from 2 lux, corresponding to complete darkness, to 20-80 lux, which are observed at twilight.
A special relay option for street lighting is the astro timer. This is a more expensive and complex device that does not require constant adjustment and protection of sensors from extraneous light. The astro timer is adjusted using the GPS coordinates of the place where it is located, time and date. Next, the device automatically calculates the sunrise and sunset times corresponding to the area. The advantages of such a device are that it is independent of the weather, installation location, and the presence of extraneous light sources. For additional convenience, you can shift the on/off time by a specific step. For example, turn off the lights 1 hour before dawn and turn them on 2 hours after sunset.
Setting up street lighting for a country house
After connecting the photo relay, it is necessary to configure it, taking into account a number of nuances. As mentioned earlier, a photo relay with a built-in photosensor has three wires at the output of the housing. They are connected as follows:
- red, responsible for the electrical load, goes directly to the flashlight, lamp or spotlight;
After connecting the photo relay, it is necessary to configure it, taking into account a number of nuances
- a brown or black wire is connected to the phase coming from the panel;
- The blue wire is connected to zero on the panel body.
An optional, but important point in ensuring safety is the grounding connection. For this purpose, a separate wire is connected to a terminal on the housing. In this case, the cross-section of the wire must be selected in accordance with the power of the expected load of the photo relay. The wiring diagram will tell you how to do this correctly.
The device is configured after its installation. To do this, you need to wait for the moment of natural light when it is desirable to turn on the lamps. Adjust the device using the settings by turning the adjustment wheel. You need to turn it until the light turns on.
It should be noted that the procedure for connecting a relay with a remote sensor is slightly different from connecting a device with a built-in photocell. Here the phase is connected to terminal A1 (L), which is located at the top of the device, then zero is connected to terminal A2 (N). From the output, depending on the location of the wire, the phase is supplied to the lights.
On a photo relay with a built-in photosensor, there are three wires at the exit from the housing
Preparing for work
The relay is configured after completing the installation procedures and connecting to the electrical circuit. To set the limits for turning the device on and off, a rotary potentiometer is installed on its body.
The degree of rotation, which determines the sensitivity of the device. On the body of the device, above the rotary potentiometer, there is a graduation marking for increasing or decreasing the sensitivity of the relay.
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Characteristics and connection features of individual sensor models: photo relay FR 601 and FR 602
The modern domestic market is represented by a wide range of photo sensor models designed for different types and lighting conditions, requiring different lamp powers and the presence of additional functions.
The most popular among standard single-phase models are the FR-601 sensor and its more advanced analogue, the FR-602 photo relay. The manufacturer of the devices is the IEK company. Both types of sensors are characterized by reliability and ease of connection. The differences between the models are insignificant; they operate on current of the same voltage and frequency, and the power consumption is 0.5 W. Externally, the devices are completely identical.
Helpful advice! To connect several lights at the same time, you need to purchase a special controller. This device will receive a signal that controls the lighting.
The only difference is the maximum cross-section of conductors for connection. Model FR-601 is designed for 1.5 mm², and FR-602 – for 2.5 mm². Accordingly, they have different rated load currents. For the FR-601 photo relay it is 10A, for the FR-602 it is 20 A. Both devices have a built-in photocell, and adjustment is allowed in the range from 0 to 50 lux with an interval of 5 lux.
The most popular among standard single-phase models are the FR-601 sensor
Such devices can be built even at home. The main difference between a homemade device and a factory IEK photo relay will be the lack of appropriate protection. This level for production models is IP44, which means protection from dust and moisture. The connection diagram for the photo relay FR 601 and FR-602 is standard and simple. The products last a long time and can withstand a wide range of temperatures.
Among the analogues of this device is the FR-75A model - a photo relay, the circuit of which is more complex for manufacturing at home. The device is less stable and durable in practical use.
Advantages and disadvantages of use
The light sensor can be built into the body of a street lamp or installed independently in the control circuit for the operation of external lighting in the local area, roadways and pedestrian paths, as well as lighting for building structures and various decorative elements. Along with other automation elements, the light sensor allows the lighting system to operate in automatic mode, which reduces the consumption of electrical energy and also facilitates the use of this system. In addition, the advantages of using light sensors in outdoor lighting systems include the following indicators:
- long service life;
- simplicity of design allows you to do the installation yourself;
- sufficiently high tuning accuracy in a wide range of light perception;
- The operation of the device can be carried out to control lighting devices using small electric currents that are safe for humans and the environment.
Appearance of a street light sensor Among the disadvantages inherent in such devices when used, it should be noted:
- susceptibility to contamination of the sensor body, which reduces its sensitivity to light perception and requires periodic cleaning of the photocell from external contaminants;
- The degree of protection of the housing must be such as to ensure reliable operation of the photo relay contacts, preventing their oxidation during use.
Connection procedure
Self-regulating supply of lighting to a room or yard is carried out using a photo relay. Connecting a photocell is not difficult:
- We turn off the residual current device (RCD).
- We lay the wiring to the area where the photo relay is located.
- Using a special device, we clean the insulation.
- We make holes at the bottom of the device body.
- We mount the photosensitive machine using the diagram. Be sure to follow the color marking of the wire.
- We connect the photocell to the light source.
Setting up the mechanism is very simple. We program the regulator to the required brightness; you can use a dark object to understand how the device operates.
If set to maximum, then the lighting will only work in complete darkness. We check the working condition.
Selection options
To choose the right photo relay, you must first decide where it will be installed and what functions it will perform. If it is necessary to turn off only one light bulb and the moment of operation is not very important, then you can get by with an inexpensive device without the possibility of regulation. This will be the perfect solution.
If you need to control an entire lighting line, then you will need a photo relay with a touch controller. In this case, a prerequisite will be electronic power units, to which a signal is received and an impulse is transmitted along the entire line.
The principal technical parameters include:
- base voltage;
- voltage value in the electrical network;
- current switching;
- response limits;
- energy consumption strength;
- maximum cross-sectional area of wires;
- options;
- physical quantity;
- the amount of permissible fluctuation;
- ambient temperature limits.
