Day-night light sensor: the principle of operation of devices and their features, rules for installing light sensors

Owners of country houses and cottages are often interested in how to equip automatic lighting on their site. They have two possible options - installing an astrotimer and a light sensor. The latter device is considered the most popular, as it has a simple design and affordable cost. Therefore, it should be discussed in more detail.

Principle of operation and device

This device is called differently. The most common name is photo relay, but it is also called photosensor, photocells, photosensor, dusk and light sensor, day / night sensor, or light control switch. The device has a lot of names, but the essence remains the same - it allows you to turn off and on the lighting in automatic mode.

The principle of operation of the light sensor is based on the ability of elements to change their properties depending on the intensity of ambient light. Photodiodes, phototransistors and photoresistors are often used. In the evening, with a decrease in illumination, the characteristics of light-sensitive parts change. After the changes can reach specific values, the relay contacts close, which are responsible for the power supply. At dawn, the changes take place in a completely reverse order, the contacts open again, and the light turns off.

Characteristics and features of choice

First you need to pick up the voltage, at which the outdoor light sensor will work: 12 V or 220 V. Another important characteristic is the protection category. Due to the fact that the device will work outdoors, the protective class must be at least IP 44. That is, objects larger than one millimeter will not penetrate into such a device and they are not afraid of splashes of water. The next selection criterion is the permissible operating temperatures.

It is recommended to select day / night street light sensors that are slightly above the average temperatures in your area.

Choose a twilight sensor it is necessary both in terms of the power of the connected lamps and the electric current of the load. Here, too, it is better to take devices with a small margin.

Some devices provide the ability to adjust the sensitivity. It is recommended to reduce this indicator when snow falls. In this situation, the light reflected from the snow surface can be perceived by the sensor as dawn. As a result, the lighting will constantly turn off and on.

Delay is also considered a very useful option. For example, if the light of car headlights hits the photo relay at night. If the delay is very small, then the light will turn off. But this will not happen if it is at least five to ten seconds.

Choosing a suitable installation location

For the normal functioning of the light sensor, it is important choose the right place for its installation. There are a number of factors to consider:

1. The device must be exposed to the light of the sun, that is, the sensor must be under the open sky.
2. The nearest windows, lights and lamps should be located as far away as possible.
3. It is undesirable for the illumination of car headlights to fall on the photo relay.
4. Do not mount the light sensors too high. This is necessary for the most convenient service.

When installing automated street lighting, it is very important to find a suitable mounting location. Often the photo relay is installed directly on the pole. However, this is not very convenient in terms of maintenance, as it will be difficult to clean at this height. It is better to place the photosensor on the wall of the dwelling, and extend the power cable to the illuminator itself.

Connection diagrams

There should be no problems with connecting the light sensor. Zero and phase are entered at the input of the device, from the output the phase is fed to the lights (load), and minus (zero) goes from the bus or machine.

If you install in accordance with the regulations, wire connections must be made in the junction box. If you need to turn off and turn on a powerful lamp on a pole with chokes, then the circuit is recommended to be supplemented with a contactor (starter). If the lighting should be started only for the period of a person's stay, for example, in a street toilet, then the installation is supplemented with a sensitive motion sensor.

In most cases, photosensors include three wires in their design: blue, red, black or brown. Keep in mind the following when installing the system:

• the red wire must be connected directly to the lamps;
• neutral (zero) from the power cable is connected to green or blue;
• the phase must be fed to brown or black.

Using these rules, you will have a completely working scheme.

Photo sensor cost

If you have a desire to install street lighting using a sensor, then, of course, you will be interested in the price of the issue.

The cost of such devices depends on the manufacturer and varies from two to ten thousand rubles. Thanks to the assortment, everyone has the opportunity to choose the most optimal solution for themselves.