Initially, motion sensors to turn on the light were used to protect the controlled territory and strategic facilities. After a while, they have found their application almost everywhere: in private and public places, in house adjoining areas. Their use is not only very convenient, but also saves about 85% of electricity.
Sensor operation principle
The principle of operation of the device is the presence of a built-in sensor. It is activated by increasing the output energy, while the level of infrared radiation should increase compared to the usual background. The light is turned on by a relay inside the sensor.
Install motion sensors to turn on the light on the stairs at the entrance, in the apartment at the entrance, on the street.
All types of devices work on a similar principle: the signals that go to the sensor to turn on the light are fixed 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 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.
Also there are 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 there are also switches with a motion sensor to turn on the light. These are devices that continue to work as long as there is movement 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
Infrared motion sensor for turning on lights outdoors or indoors, responds to thermal radiation emitted by living beings or other moving objects. This action is carried out with the help of lenses that are indicators.
The main purpose of infrared sensors are:
- Savingselectricity. The light is turned on only when needed.
- Presence effect. Installing the sensor in the entrance, on the plot, under the windows, and so on, creates the impression of presence. Such a trick scares off robbers or bandits and provides peace of mind.
The main advantages of infrared sensors are:
- high precision;
- wide temperature range;
- safety for pets and people.
Among the shortcomings noted:
- high sensitivity to household appliances;
- reacting to direct sunlight;
- immunity to objects in a protective coating that does not transmit thermal radiation.
However, for some people, all the benefits of this device are not so important and cause irritation due to the constant switching on and off of the light. In this case, it is recommended to use additional switches, with which you can customize the entire system to individual requirements.
Ultrasonic transducer
Ultrasonic sensors work on the principle of measuring the nearest space with sound waves. They convert sound waves that are reflected from objects at the slightest movement. The frequency of reflections is measured every second, as a result, a kind of echo sounder is created. The signal is transmitted to the sensor, and it, in turn, activates the lighting on or off.
Most often ultrasonic sensors are used in the automotive industry forparking sensors. The connection diagram of the motion sensor to turn on the light should be attached to the device. The technical documentation indicates the maximum viewing angle and gives recommendations on mounting the device. An example is shown in the picture below.
Among the main advantages of the device are:
- possibility of installation in large areas;
- weather resistance;
- insensitive to dirt and dust;
- compatibility with different case materials;
- widest operating temperature range.
The main disadvantages are:
- reacting to pets;
- prolonged use may cause headaches.
Microwave sensor
This kind of motion sensor for turning on the light functions by emitting high frequency electromagnetic waves. They, falling on a moving object, are reflected, which is immediately fixed by the sensor. The slightest change in the signal is picked up and activates 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 microwave sensor:
- reacting to objects moving behind the barrier;
- immunity to aggressive environments.
The main drawback 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 pass throughminimum.
Combined sensor
Motion sensor to turn on the light of the combined type involves the simultaneous use of two or more object detection technologies.
Their undeniable advantages:
- maximum accurate operation;
- absolute control of the entrusted territory;
- wide range of individual settings.
Despite the quality of such devices, they have some drawbacks:
- 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 has ever seen such a motion sensor to turn on the lights in movies or heard about it. One clap is enough to turn the light 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 light.
It is quite convenient to independently adjust the lighting remotely, while many confuse the cotton mechanism with the acoustic one. However, these sensors work a little differently.
Cotton sensor is used not only to control lighting 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. First cotton includesvoltage, the second turns off. In addition, it is important to consider the place where the system is installed. For example, if this 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 halls, workshops, industrial premises is not recommended.
Acoustic sensor
The main difference from the previous type of device is the sensor's response not only to cotton, but to any sound. Most often, an acoustic sensor is installed in entrances in order to save energy. Depending on the settings, the light turns off after a specified time.
Sensor parameters
Each motion detector for turning on a street-type light or for a room has its own technical characteristics, but it has its own regulations and standards.
Let's take a closer look:
- Voltage - from 220-240 V and not more than 50 Hz.
- The turn-on time depends on individual settings.
- On timer 2-8 sec.
- Sensitivity to light 2-1000 lux. It is set on the power supply. Simply put, the set parameter of 100 lux performs the task only at night.
- Viewing distance - up to 15 meters. Combined sensors make it possible to increase this distance.
- Firing at a rate 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 occurs when moving too fast.
- The current limit can also be different. In this case, everything depends on the area of application of the sensor, whether it will be the minimum value or the maximum value up to 1500 W. The load is determined by the electromagnetic relay.
- Viewing angle depending on installation location. For ceiling sensors 360°, for corner sensors 100°, for wall sensors 180°. The determining factor is the installation height of the device, the higher it is located, the wider the view.
Connecting the outdoor sensor
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 area with marks of the places where it is planned to install lighting, and highlight the zones with the predominant presence of people. In addition, the following factors are taken into account when designing:
- Direct sunlight should not fall on the light switch, if possible, it is better to move it to the shade.
- The sensitivity of the device is selected taking into account the coverage area, but without capturing unnecessary territory.
- There must be no obstacles between the sensor and the intended object, including plants.
Scheme for connecting the motion sensor to turn on the light is shown in the picture below.
Indoor sensor connection
Now let's talk abouthow to install a motion sensor to turn on the light. The device must be installed in such a way that it controls the entire area that needs to be illuminated. If the layout has a complex configuration, it is better to purchase several devices. It is also important to consider the detection angle of the device being used.
When designing a plan for the location of lighting fixtures, you need to take into account the field of view and range limitations.
There are a few more nuances that you should consider before installing motion sensors:
- If there are pets in the house, weight-limited sensors are recommended.
- The sensor should not be obstructed by massive pieces of furniture.
- To exclude a false reaction to warm air flows, there should be no heaters in the coverage area.
- The device must not be exposed to direct light.
The installation of modern motion sensors can eliminate many inconveniences, make moving around the house and the site as comfortable and safe as possible in the dark.
