LED street floodlights with a motion sensor are widely used in industry and in everyday life. They are necessary for the protection of territories, warehouses, lighting of yards and streets, as well as outbuildings of cottages and country houses. The use of spotlights on LEDs allows to increase the reliability of devices and reduce electricity costs.
Construction of an LED floodlight
The LED floodlight consists of the following components:
- LED emitting module;
- corps;
- reflector;
- diffuser;
- Power Supply.
The following types of LEDs can be used as elements of the emitting module:
- powerful LEDs (power of 1, 3 and 5 W);
- high-power LEDs (SOV technology);
- LEDs of the SMD type.
The power of devices of the first type is determined by the size of the crystal. The crystal emits blue light, which is transformed into white light with the help of a phosphor. The disadvantage of such LEDs is their complexity and high cost. A large number of such devices are required to obtain powerful spotlights. Their advantage is the simplicity of the heat removal device.
Chip on Board (Chip on Board) technology is a more progressive method of creating powerful light sources for floodlights.
The production of LEDs using SMD (Surface Montage Details) technology has been going on for a long time, and devices of this type are used in LED lamps and strips. Increasing the power of devices of this type allows you to use them in searchlights.
The most compact are the spotlights on SOV LEDs, and the largest ones are the spotlights on powerful LEDs.
An important issue in the design of an LED floodlight is related to the removal of heat from the emitting module. Although the LEDs have a fairly good CCD, the pn junction of the crystal can heat up to a temperature of +80 ° C. At this temperature, the junction degrades, which leads to a sharp decrease in the light flux. To prevent this, LEDs are lubricated with heat-conducting paste and placed on a circuit board with good thermal conductivity. A radiator is used to remove heat from the board. Different manufacturers make radiators of different shapes from different materials.
The body of the spotlight is made of aluminum alloy and has high thermal conductivity to ensure heat dissipation.
Reflectors are used in searchlights to create a directed, diffused or mixed light flow. Reflectors are symmetrical, asymmetrical, circularly symmetrical. These reflectors are made of metal, covered with aluminum spraying, which ensures the creation of an even light flow. Thanks to reflectors and other optical elements, different lighting angles are realized in spotlights.
The spotlight diffuser is usually made of tempered glass.
Power supply of the spotlight on LEDs from the network is provided by a special source of stabilized current – a driver. Usually, such a driver is installed inside the projector housing. For promising modern models of spotlights with 10-watt LEDs, a driver with a current of 350-700 mA and a voltage of 20-38 V is used.
LEDs are highly reliable, and their service life is defined as 50,000 hours. In order for the searchlight to have a high reliability index, all its elements must be reliable. Including the driver.
Motion sensors
The motion sensor turns on the spotlight when a moving object appears in the protected area. It can be a person, a car or an animal.
Thanks to the presence of a motion sensor, you can save electricity and protect the house from intruders. Motion sensors are active and passive, can work in ultrasonic, microwave or infrared wave ranges. Infrared motion sensors are most often used, as they are the safest for humans. Structurally, motion sensors can be external or built into the LED floodlight.
The infrared sensor turns on the spotlight only in the following cases:
- there is no sunlight. At the same time, the appropriate activation threshold (LUX regulator) is set;
- a moving object appears in the area of effect. At the same time, sensitivity control (SENS control) can be used to filter signals from small animals.
In addition to these two adjustments, the motion sensor has a “Time” adjustment, with which you can set the time for lighting the area after people leave it.
Spotlight installation
The following rules must be taken into account when installing the spotlight.
The searchlight should be installed at a height corresponding to its power. At the same time, it is desirable to provide for the possibility of connecting it to the power network.
The remote motion sensor should be installed so that it can respond to the appearance of moving objects in the surveillance area, and it cannot be damaged by intruders. For example, a standard motion sensor with a suspension height of 2.5 m monitors a range of up to 12 m, which is enough for a 10 W LED floodlight.
There should be no obstacles between the sensor and the observation area.
To power the floodlight with the sensor, you need to make a voltage connection. At the same time, the cross-section of the spotlight wire should be at least 0.5-1.5 mm².
After connecting the projector, do a motion test. For this purpose, all the controls (SENS, LUX and TIME) are set to the maximum position. Gradually approaching the searchlight, determine the moment of its ignition and the range of the sensor. After the maximum delay time (about 10 minutes) turns off, perform the final adjustment of the regulators:
- use the SENS control to adjust the sensitivity. Determine the dimensions of the triggering objects and the range of the sensor;
- use the LUX (“Lighting”) regulator to set the time of day of the spotlight’s operation (usually dusk).
- use the TIME knob to set the time delay for turning off the spotlight.
Selecting a spotlight
In order to correctly choose a floodlight with a motion sensor, you need to know its characteristics and evaluate them from the point of view of application for given conditions.
For example, to estimate the area covered by a motion sensor, you need to know the viewing angle of the sensor and its range. The viewing angle is usually specified in the sensor specifications, and the range is determined by its sensitivity, which can be adjusted.
Table 1 shows the main characteristics of some types of floodlights with motion sensors. As the emitter in the floodlights, LEDs of the SOV type are used.
Table 1
| Company | Power, W | Luminous flux, lm | Color temperature, K | Radiation angle, degrees |
| Zonhan | 10 | 1000 | 7000 | 120 |
| Uniel | 10 | 750 | 650 | – |
| Evlan | 20 | 1300 | 6000 | 120 |
| Kreonix | 30 | 2560 | 6500 | 105 |
| Kreonix | 50 | 4200 | 6500 | 105 |
| China | 100 | 9000 | 4000 | 100
|
Since these floodlights are designed for outdoor use, they have a degree of protection against dust and moisture not lower than IP65. Products work at temperatures from – 40 to + 60 ° C. All floodlights, with the exception of the first Chinese product, which requires a direct current source, are powered by an alternating current network.
Most of the considered floodlights have a color temperature of about 6000-7000 K. They emit cold white light. The angle of light emission in spotlights is 100-120 °.
The use of high-reliability LEDs as emitters makes it possible to make LED spotlights with a service life close to the service life of LEDs. Manufacturers estimate this service life from 35 to 50 thousand hours.
Most spotlights have a remote motion sensor. The Uniel product has a built-in motion sensor.
Conclusions
- The use of floodlights on LEDs with motion sensors automates the switching on and off of lighting on the street, and allows you to save electricity
- There are a large number of floodlights of different capacities and different manufacturers on sale.
- For the correct choice of a street floodlight, it is necessary to take into account the correspondence of its characteristics and the conditions of its use.
- The spotlight on LEDs with a motion sensor can be installed and adjusted independently.