Initially, motion sensors to turn on the light were used to protect the controlled territory and strategic objects. After a while, they found their application almost everywhere: in private and public places, in adjoining areas. Their use is not only very convenient, but also saves about 85% of electricity.
The principle of operation of the sensor
The principle of operation of the device is the presence of an integrated sensor. It is activated by increasing the energy at the output, while the level of infrared radiation in comparison with the usual background should increase. The light is turned on thanks to a relay inside the sensor.
Install motion sensors to turn on the lights on the stairs in the entrance, in the apartment at the entrance, on the street.
All types of devices work according to a similar principle: the signals that are sent to the sensor to turn on the light are captured by the controller and transmitted to the command post:
- alarm;
- ventilation system;
- relay to turn on the light;
- air conditioning system.
Most of these features are used in the smart home. You can control the system, being not only in the house, but also outside it.
Types of sensors
Modern manufacturers offer a wide variety of devices that in one way or another determine the movement. The very concept of "motion sensor" implies 4 types of devices, depending on the installed main sensor element:
- Infrared
- Ultrasonic
- Microwave
- Combined.
There are also sound sensors or cotton ones. In order for the device to respond to movement in a timely manner, it is important to install it in the right place according to the instructions.
On sale are also switches with a motion sensor to turn on the light. These are devices that continue to work while movement is present in the sensitivity zone. Simply put: while a person is moving, the light bulb will not go out. Such a device allows you to slowly get the keys and open the doors, for example.
IR sensor
An infrared motion sensor to turn on the light on the street or indoors reacts to the thermal radiation emitted by living things or other moving objects. This action is carried out using lenses, which are indicators.
The main purpose of infrared sensors are:
- Saving electricity. The light is turned on only when necessary.
- The effect of presence. The installation of the sensor in the entrance, in the garden, under the windows and so on, gives the impression of presence. This trick scares robbers or bandits and provides peace of mind.
The main advantages of infrared sensors are:
- high precision;
- a wide range of temperature conditions;
- safety for pets and people.
Among the shortcomings are noted:
- high sensitivity to household appliances;
- response to direct sunlight;
- immunity to objects in a protective coating that does not transmit thermal radiation.
However, for some people, all the advantages of this device are not so important and cause irritation due to the constant on and off light. In this case, it is possible to recommend the use of additional switches, with which you can configure the entire system to individual requirements.
Ultrasound sensor
Ultrasonic sensors work on the principle of measuring the nearest space with sound waves. They transform sound waves, which at the slightest movement are reflected from objects. The frequency of reflections is measured every second, resulting in a kind of echo sounder. The signal is transmitted to the sensor, and it, in turn, activates the on or off lighting.
Most often, ultrasonic sensors are used in the automotive industry for parking sensors. The motion sensor connection diagram for switching on the light must be attached to the device. The technical documentation indicates the maximum viewing angle and gives recommendations on the installation of the device. An example is presented in the picture below.
Among the main advantages of the device are:
- the ability to install in large areas;
- weather resistance;
- insensitive to dirt and dust;
- compatibility with various materials of the case;
- the widest temperature range of work.
The main disadvantages are:
- response to pets;
- with prolonged use, there is a likelihood of headaches.
Microwave sensor
This kind of motion sensor to turn on the light operates by emitting high frequency electromagnetic waves. When they hit a moving object, they are reflected, which is immediately detected by the sensor. The slightest changes in the signal are captured and activate the program programmed by the owner. The principle of operation is similar to the previous type, the difference lies in the signal range.
Advantages of the microwave sensor:
- response to objects of movement beyond the barrier;
- immunity to hostile environment.
The main disadvantage is the harmful effects on the human body. Therefore, such a sensor, as a rule, is installed on the street, in vast protected areas where people passability is minimal.
Combined sensor
A motion sensor to turn on a light of a combined type involves the simultaneous use of two or more object detection technologies.
Their undeniable advantages:
- the most accurate response;
- absolute control of the entrusted territory;
- wide range of individual settings.
Despite the quality of such devices, and they have some disadvantages:
- It is better to entrust the installation of a motion sensor for lighting to a specialist due to some features of the device
- in case of failure of one of the equipment sensors, you will have to reconfigure the entire system.
Cotton sensor
Probably everyone at least once saw such a motion sensor to turn on the light in movies or heard about it. One clap is enough to turn the lights on or off. This is especially true for children who do not like to go to bed in the dark and people with disabilities. And adults are often too lazy to get out of bed to turn off the lights.
It is quite convenient to independently adjust the lighting remotely, while many confuse the cotton mechanism with the acoustic. However, these sensors work somewhat differently.
The cotton sensor is used not only to control light devices, but also ventilation, transformers and other electrical equipment. When installing this system, it is important to comply with the requirements for the permitted load power. The first clap turns on the voltage, the second turns off. In addition, it is important to consider where the system is installed. For example, if it is a banquet hall, then applause can provoke a light show. Best suited for this:
- utility rooms, pantries, basement, etc .;
- bedroom or nursery.
Installation in crowded rooms, workshops, and production rooms is not recommended.
Acoustic sensor
The main difference from the previous type of device is in the response of the sensor not only to clap, but to any sound. Most often, an acoustic sensor is installed in the entrances in order to save energy. Depending on the settings, the light turns off after a specified time.
Sensor Parameters
Each motion sensor for turning on street-type light or for a room has its own technical characteristics, but it has its own norms and standards.
Let's consider in more detail:
- Voltage - from 220-240 V and not more than 50 Hz.
- Start-up time depends on individual settings.
- On-timer 2-8 sec.
- Sensitivity to lighting 2-1000 lux. It is set on the power supply. Simply put, the set parameter of 100 lux performs the task only in the dark.
- Viewing distance - up to 15 meters. Combined sensors make it possible to increase this distance.
- Operation at a speed of 0.5 to 1.5 milliseconds. For example, if a person moves very slowly, his thermal radiation merges with the general temperature background and the sensor may not work. The same situation is observed when moving too fast.
- The current limit can also be different. In this case, it all depends on the scope of the sensor, whether it will be the minimum value or the maximum up to 1500 watts. The load is determined by the electromagnetic relay.
- Viewing angle depending on the installation location. For ceiling sensors 360 °, for angular 100 °, for wall 180 °. The determining factor is the installation height of the device, the higher it is located, the wider the view.
Outdoor sensor connection
Outdoor use of weatherproof devices is recommended. In order for the sensor to work accurately and in a timely manner, it is necessary to periodically clean the lens through which the signal is transmitted.
First of all, it is necessary to schematically depict the site with notes on the places where the installation of lighting is planned, and to identify areas with a predominant location of people. In addition, the following factors are considered during design:
- Direct sunlight should not fall on the light switch, if possible it is best to move it into the shade.
- The sensitivity of the device is selected taking into account the coverage area, but without capturing unnecessary territory.
- There should not be any obstacles between the sensor and the intended object, including plants.
The motion sensor connection diagram for turning on the light is shown in the picture below.
Sensor connection indoors
Now let's talk about how to install a motion sensor to turn on the light. The device must be installed in such a way that it controls the entire territory that needs to be covered. If the layout has a complex configuration, it is better to purchase several devices. In addition, it is important to consider the angle of detection of the device used.
When designing a plan for the location of lighting devices, it is necessary to take into account the field of view and the limitations of the range.
There are several more nuances that it is advisable to consider before installing motion sensors:
- If the house has pets, it is recommended to purchase sensors with a weight limit.
- The sensor should not be blocked by massive pieces of furniture.
- To exclude a false reaction to the flow of warm air, there should be no heating appliances in the coverage area.
- The device must not be exposed to direct light.
The installation of modern motion sensors can relieve many inconveniences, make moving around the house and the site as comfortable and safe as possible in the dark.