The photocell or photoelectric relay is widely used, is a device that is among the pioneering devices of home automation, although today it seems to be something extremely common. We will talk about exactly what the photocell is, how the photocell works and how to install a photocell, come on guys!
Photocell: What is it and how does it work?
The photocell or photoelectric relay today may seem like a simple and common thing, but when it was invented, it definitely brought a lot of practicality and electricity savings. We can mention that the main function of the photocell is to enable a given circuit to be activated or not automatically, through the amount of light detected by the photocell.
With this function, there is a multitude of applications for photocell, be it residential, building, industrial and others. One of the practical examples of application for the photocell, is in the activation of the lamp posts, which light automatically when dark.
It is important to note that the name photocell is not the most suitable for this device, although it is commonly used by many people, including some professionals in the field. In fact, photocell, photovoltaic cell, photoelectric cell are terms used to refer to solar energy collector cells, but as both devices work according to the lighting principle, as a source of activation or source of energy, this confusion with the names is very common.
The operation of every relay is basically configured as a normally open or normally closed contact, and its activation is according to some factor or configuration, that in the case of the photoelectric relay, this factor is the amount of light that falls on the sensor of the photocell, which is nothing more than an LDR sensor (light dependent resistor, which translating is light dependent resistor).
The LDR Sensor is fundamental for the operation of the photoelectric relay, since the LDR sensor is capable of varying a small resistance according to the amount of light that falls on it, that is, according to the variation of this resistance it is possible to make a current, whether or not it circulates through a coil, which will cause a contact to open or close, thereby switching the circuit that will be connected to this relay.
As well as a simple switch, the photoelectric relay also basically has the function of activating or not a lighting point, however the photocell is responsible for activating this lighting point according to the variation of light on it, that is, if it has little luminosity on the photocell it activates the illumination point.
The most common place where we can find the photoelectric relays is in the activation of lamps on lamp posts, in addition to being able to be used to automate the lighting in several areas, such as gardens, garages, corridors, trails and others.
Photocell: Care for installation.
Before teaching how to install photocells, we must take some precautions. The first care that we must take is to make sure that the circuit is de-energized, so turn off the circuit breaker of the circuit where the photocell or general circuit breaker will be installed.
Using a test switch or multimeter, make sure that the circuit is off and that no one will accidentally connect this circuit, for this we recommend the use of a padlock.
It is important to note that the maximum power of the vast majority of photocells available on the market is 1000W, and thus the maximum electrical current that a photoelectric relay is capable of withstanding would be approximately 7.8A for a 127V or 4.5A circuit. for 220V circuit.
It is necessary to be attentive in relation to the position that the photoelectric relay will be installed, because if the relay is installed with the LDR sensor display facing directly to the lamp that it will be activating, a “blink blink” effect will occur. Therefore, the display should always be installed with the LDR sensor display facing the direction where there is less light.
Photocell: How to install.
The installation of the photocell is relatively simple, because with the exception of supplying the photoelectric relay for its internal operation, the rest of the installation is the same to turn on a lamp, that is, it is the same of using a photoelectric relay instead of the switch the switch.
The first step to install the photocell is to make its supply, in this case we supply with phase and neutral for 127V installations or phase and phase, for 220V installations, remember that these values may change according to your region and type of installation . See the wiring diagram in the image below.
The second and last step is the installation of the lamp, so we connect the return cable of the photoelectric relay directly to the central terminal of the receptacle, for safety reasons. Then we connect the neutral cable to the other terminal of the receptacle, as we can see in the connection diagram in the image below.
To facilitate the understanding of how to install the photoelectric relay, this video below shows step by step the installation of the photocell, so that there is no doubt about its correct installation.