Presence sensors for turning on the light are the most common option for providing automatic control of lighting in the house and on the adjacent territory. It is enough to connect a special device to the power supply circuit that powers the lighting equipment, and if any moving object appears in the sensor's field of action, it will immediately send a command to turn on the light in the desired area. The light turns off after a certain period of time, when the object leaves the treated area of action or stops. The main function that any modern presence detector has is to provide comfort.
Where is DP used
There are many purposes for which a presence sensor can be used:
- turning on and off the light;
- control of the lighting system;
- adjustment of the state of various devices.
The most common application for such equipment is the modernization of the lighting system of residential apartments, houses and cottages. Sensors are installed where people are not very long and do not go there often:
- cellar;
- pantry;
- bathroom;
- entrance;
- attic;
- restroom;
- corridor.
Some people prefer to install such equipment in every room in their home, including an additional sensor at the front door, which will turn on the light in front of it when it detects the return of the owner.
Presence detectors are widely used in office, educational and industrial establishments, where they are installed in halls, hallways, fire exits and other facilities.
Presence detector types
Depending on how the sensor registers movement in its area of action, it can be:
- infrared;
- microwave;
- combined;
- ultrasonic.
There are sensors that only perceive the incoming radiation - they are usually called passive. If the sensor simultaneously receives and emits signals, it is classified as active.
The equipment can be acoustic or sound. These devices send a signal to turn on the light in the event that the noise level near them exceeds the set value.
There are various options for controlling the presence detectors. On the market of modern devices, you can find those that allow the user to independently set the indicators and change them at any time, including the distance of action, the degree of sensitivity and much more. At the same time, others set all parameters fully automatically.
The latter category of devices immediately sends a command to turn on the light after a moving object appears in the area of action, and after it disappears, a command is sent to turn off the light. In this case, it happens that a person moved around his territory, but then decided to sit on a bench, and the sensor, which stopped recording movement in its area of operation, automatically sent a command to turn off the light. To eliminate such unpleasant situations, the connection diagram is supplemented with a conventional switch, with which you can forcibly ignite the lamps.
Depending on the installation location, the sensors can be internal or external.Both of these categories practically do not have any noticeable structural differences, with the exception that sensors installed on the street are additionally equipped with a powerful case that protects them from the effects of various harmful factors.
Recessed devices that are installed in the wall or ceiling are more popular, but there is also a more economical option for purchasing surface-mounted sensors that will be constantly visible.
Extra options
There are also several additional parameters by which modern presence detectors are distinguished:
- Range of work. Depending on the characteristics of the operation, the device can be triggered when motion is detected at a distance of up to 23 meters or even more. Most often, such a large working radius is needed for outdoor devices or houses with long corridors. In small rooms it is quite sufficient to use equipment with a working radius of no more than 10 meters.
- Load power. The range of this indicator is simply huge - from 7 to 2,400 watts. When choosing one or another option, for a start it is worth calculating the power of the lighting that will be connected to the sensor. If you plan to gradually connect new equipment over time, a new sensor or intermediate relay should be added to the circuit. It also happens that the total power of the devices connected to the sensor significantly exceeds the calculated power. Because of this, the relay of the device breaks down. In such a situation, the only correct solution would be a complete replacement of the equipment.
- Load type. It all depends on what kind of lamps are used in the lighting system of an apartment or house: halogen, fluorescent, LED or ordinary incandescent lamps.
- Visibility angle. This parameter depends solely on the installation location of the device. If it detects movement in the corridor, a large trigger angle is unnecessary. If you plan to put the sensor somewhere outside in the middle of the yard, it is best to buy a device with a large coverage.
Any outdoor presence detector must be equipped with effective protection against external factors such as moisture, temperature fluctuations or dust. If the device is installed in a residential or office space, it does not need a high degree of protection.
Customization features
The sensors are adjusted for the timely switching on of the light through special potentiometers, the characteristics of which change at the bottom of the case. Often, the user can independently set the switch-on time, change the standard degree of sensitivity, and also adjust the signal to turn on the light. According to the last parameter, most often the characteristics are set so that the device works only with the onset of darkness, since the operation of the lamps in the daytime is meaningless.
The sensitivity of the sensor is changed to ensure that the device works accurately, turning on the light always at the right time, without showing false alarms. The greater the sensitivity of the installed sensor, the more often it will register movement in its area of action. The main task when setting up is to achieve such an effect that it reacts only to people, excluding the inclusion of light when moving any animals, insects, etc.
By setting the time, you can ensure that the device does not turn off the light automatically 15 seconds after it turns on. Often this indicator changes by 2-15 minutes, depending on how much time a person spends on average at the location of the sensor.
How sensors work
Infrared
The design of such equipment includes a pyroelectric unit, as well as a lens, which includes several small lenses, as well as special electronic components. The sensor is triggered immediately after the infrared wave disappears from the photocell, if a person becomes the source of this interference.
Microwave and ultrasonic
Such devices operate using a special high-frequency radiation generator and receiver. In most cases, they can be found as a separate element of the security system. Some people prefer to use them when arranging lighting. The sensor constantly emits signals. If they return with a different frequency, it determines the cause of the interference and is triggered if it detects the movement of a person.
Noise
Such equipment is triggered after some unusual sounds are recorded near it: pops, footsteps, conversations. An ordinary microphone is used as a signal receiver, the sensitivity of which can be adjusted by the user himself.
Thanks to the use of presence sensors, you can significantly reduce the cost of a lighting system, since it will not constantly waste energy and will last longer. Therefore, modern sensors are perceived not only as an option to make your life more convenient, but also as an effective means of saving.
