The principle of operation of the motion sensor for lighting

According to expert estimates, installing a motion sensor can save from 20 to 58% of electricity. Installation of such a device is very beneficial if you select a detector taking into account its characteristics and features of use.

Types of motion sensors and characteristics

There are several types of detectors that differ in that they respond to different conditions - they detect an object in different ways.

• Infrared - react to thermal radiation, therefore, turn on the light when it enters the detection zone of a moving object that emits heat, including animals. Due to the latter, in apartments with pets, especially large ones, they are not recommended to be installed.
• Sound or acoustic - they are triggered when noise occurs, so the light turns on even before the immediate appearance of an object in range.
• Ultrasonic - emit ultrasonic waves and compare the reflected signal with the emitted.
• Microwave - similar to ultrasound, only the action is based on the emission of microwave waves that can pass through obstacles (thin brick walls, wooden partitions). Sensors will still respond to movement.
• Combined - combine several options for detecting an object, for example infrared and acoustic, so that the disadvantages of one detection method are compensated by another.

According to the place and method of installation, motion sensors are ceiling mounted (they are also called wall or laid on) and are built into the socket.

• Ceiling detectors are equipped with universal brackets. They are mounted on a flat surface, can be rotated. The installation height is about 2.5 m.
• Detectors that are embedded in the wall socket are installed flush with the wall surface. For installation, usually choose a site near the lamp.

According to the type of power, the sensors are wired and wireless. The wired ones are powered from the 220 V mains, and the wireless ones that transmit the signal via radio waves operate from 12 V rechargeable batteries.

In some models, the motion sensor is not the main but the auxiliary part: in LED lamps with a motion sensor or sensors with a siren. The first are equipped with an active or passive controller. Products with an active controller emit a signal, and then the reflected waves are compared. This helps to minimize false positives, but the cost of such devices is higher. Luminaires, supplemented by a motion sensor with a passive controller, are popular due to their lower cost, but the percentage of false positives is higher because they only work on receiving waves.

Autonomous sensors with a siren, when activated, turn on the siren. Modern models can also give not only an audio signal, but also a light signal, send a message about the incident via a GSM-communication channel to the owner’s telephone or security control panel.

Principle of operation

The principle of operation of the IR motion sensor for lighting is the reaction to the appearance or disappearance of infrared light on the photocell. A noticeable infrared light emits a person, due to the fact that his body temperature is much higher than the ambient temperature. However, sometimes the sensor may respond to thermal radiation from household appliances. The latter leads to false positives.

In the center of the device, on which the signal processing circuitry is located, is a pyroelectric IR sensor.The main lens consists of many small lenses, each of which focuses IR light on the plane of the photocell, and one of them directly on the photocell itself, and the signal is recorded. During the movement of a person, the focus of the lens shifts from the photocell, the signal disappears. At the same time, another lens is connected, which in turn focuses the infrared light, and the signal reappears. The more lenses, the higher the sensitivity of the sensor. In the device they can be from 20 to 60.

IR detectors are completely safe, do not produce any radiation, but require careful choice of location.

Ultrasonic sensors emit a signal at a frequency of 20-60 kHz. They work on the principle of a locator, i.e. compare the reflected signal with the original. The reflected waves are received by the receiver. If the signal changes due to the Doppler effect, the detector closes the circuit.

Devices are inexpensive, drive the mice away, as they cause discomfort in animals, but differ in an important feature: they accurately respond only to fast movements. Sensitivity adjustment is possible, but then the percentage of false positives increases.

Microwave sensors emit waves in the microwave range, most often at a frequency of 5.8 GHz. According to the principle of operation, they are similar to ultrasonic ones, because thanks to the built-in processor they compare the reflected signal with the emitted one. Their main disadvantage is that they constantly emit microwave waves, which are harmful to human health. The radiation power should comply with WHO requirements: not more than 1 mW / cm2.

Motion sensors react to movement in the detection area, the appearance of obstacles. They can be used in burglar alarm systems, as well as for switching on devices, in particular lighting elements. Ultrasonic detectors are widely used in automatic parking systems, long corridors.

Criterias of choice

To choose the right model, you need to take into account the recommendations:

• Place of installation. The required IP protection class depends on this. On the street, where the sensor is exposed to water and dust, it is preferable to devices with a degree of protection IP65. The detector mounted under a canopy can have IP44 protection class, and sensors with a lower degree of protection are quite suitable for rooms.
• Type of sensor. Since the instruments differ in the way they detect moving objects, it is necessary to determine which variety is suitable in a particular case. For example, it is better to purchase infrared sensors for the home, microwave for the alarm systems, and ultrasonic for the entrances.
• Viewing angle. Depends on the number of entrances to the room. If there are 2–3 of them, a motion detector with a viewing angle of 360 ° will do its best. If the light should turn on when passing through one section of the room, you can do with a device with a viewing angle of 180 °. To do this, you need to direct him in the right direction.
  
• Power. The detector is selected taking into account the power of the fixtures. The power of the sensor should be a little more.
• Radius of action. The detection radius or the maximum distance to the object to which the detector reacts is of great importance. If the room is small, a sensor with a minimum detection radius is enough. When choosing a detector for street lighting, you need to approach the definition of this parameter more responsibly.
• The presence of a photo relay. Thanks to the photo relay, the lighting will turn on only when it is needed - at an insufficient level of illumination.
• Protection from animals. This function is necessary so that in the presence of pets, such as dogs, the sensor does not respond to their movement.

The last aspect is the manufacturer. It is not recommended to buy sensors at a suspiciously low price, from unknown manufacturers.

Connection Features

There are six principal options for connecting a motion sensor:

• Wireless (battery operated).Such detectors are installed where it is difficult or impossible to connect the power line.
• Directly to the lamp. This connection scheme is the simplest, but inconvenient from the point of view of use in the apartment, because the light will turn on only by the reaction of the motion sensor. If there is no movement, the light will turn off.
• Through the switch. This connection method allows you to organize constant lighting bypassing the detector.
• Through the outlet. In this way, connect the detector when it is needed. For example, if it is not equipped with a photo relay, it will be disconnected from the network during the day.
• In combination with another detector. A parallel connection of motion sensors is necessary on the street or in the house, where due to the large area or the presence of obstacles, one detector will not be enough. Detectors are mounted at several points.
• With magnetic starter. It is used when the sum of the powers of all light sources exceeds the rated power of the sensor. The most widely represented devices with rated power ranging from 500 to 1000 watts.

One of the important points is the choice of installation location, because it is necessary to position the sensor so as to minimize dead spots. Tilt angle and height are taken into account.

Having chosen the circuit and the place of connection, you can proceed with installation:

1. On the input panel, the power supply is turned off.
2. Connect the wires to the sensor and the lamp. It is important not to reverse polarity. The colors of the wires and the markings above the connectors will help you orient yourself.
3. Then it is necessary to set the regulators in the necessary positions so that the sensor operates in optimal mode.

There can be up to four regulators:

• Lux - lighting level when triggered. The adjustment is performed by initially setting the maximum value. When dusk sets in, it is necessary to adjust the position so that the sensor responds.
• Time - shutdown delay. Set the device from the minimum values.
• Sens - sensitivity. It is set up so that the sensor does not work on small animals, but only on a person. It is recommended that you adjust from the maximum position, gradually reducing sensitivity.
• Mic - noise level at which the operation occurs.

If you adjust all the parameters correctly, you can save up to 50% of electricity.

DIY motion sensor

To make a motion sensor with your own hands, you can use the ready-made scheme.

To make a home-made device, you will need the following tools, parts and materials:

• voltmeter;
• soldering iron;
• connecting wires;
• gasket for mixer;
• screw;
• laser pointer;
• relay RES 55A;
• transistors
• resistors;
• photodiode ФД 265;
• Power Supply.

Assembly Instructions:

1. The connector is cut off from the power supply and a positive contact is found with a voltmeter. Solder a 10 kΩ resistor. And already a photodiode is connected to the resistor by a cathode.
2. The anode of the photodiode is soldered to the building resistor. The emitter of the transistor is soldered to the negative of the resistor. The base VT1 is connected to R1 and soldered to the desired collector.
3. The emitter of the transistor VT2 is connected to the minus, and the relay is connected to the VT2 collector. With the plus of the power supply, another relay contact is soldered.
4. Then take the laser pointer. Two additional wires are connected to the power supply.
5. The cord is inserted into the plumbing, and then with the hat inward into the pointer. The hat should abut against the inner spring.
6. One power wire is connected to the screw, the other is inserted between the pointer body and the gasket.

The sensor should be installed at a height of about a meter from the floor. The pointer is mounted parallel to the floor so that the beam from it hits the photodiode. It is necessary to ensure that the photocell and pointer are not dirty, otherwise the sensitivity will be reduced.

Repair Rules

Disassembly of the sensor is performed in a specific algorithm.Using an example of a motion sensor of the DD 009 type, the order will look like this:

1. They put the regulators in the extreme position so that later there will be no problems with setting the settings.
2. Then they are carefully removed with pliers.
3. Using a screwdriver, like a lever, they pry the holder's mount and pull out the sphere.
4. Where the halves of the sphere are connected, you need to insert a flat screwdriver, turn it, and the latches will open.
5. A board is installed inside, it is also fixed on latches. They are bent off with a screwdriver. Under the board is a plastic plate, which is fixed in the center with a self-tapping screw. Under the plate is a power board.

Often a relay fails. It is located just on the power board.

Assembly is carried out in the reverse order.

The motion sensor rarely fails, but if any malfunction occurs, you can fix it yourself. There are 5 common problems:

• the sensor does not turn on - it may occur due to voltage drops, mechanical or atmospheric effects;
• the detector does not turn off - relay contacts may be closed or incorrect settings may be made;
• It works on its own: it turns on and off - this occurs due to overheating in the sun, exposure to electromagnetic fields, getting into the detection zone of any objects;
• falsely triggered - incorrect settings or bad contacts;
• does not turn off the lamp when the movement has stopped or does not turn it on - it may be explained by a decrease in the detection zone with time.

There are two ways to repair the device, depending on the malfunction: by disassembling the device and checking the internal parts or by performing the adjustment again.

The obvious signs of a disassembly failure are:

• the smell of burning;
• darkened, swollen, or loose elements;
• burned out circuit board.

Burnt and swollen parts must be replaced by similar ones, the tracks should be restored with a jumper, and poorly fixed elements should be re-soldered.

The best models

The best manufacturers of motion sensors for turning on the light are: Rev Ritter, Orbis, Camelion. The TOP-3 of the best motion sensors for lighting included:

• Orbis 360 degrees CIRCUMAT PRO CR white remote control OB134912. A Spanish-made sensor with a detection angle of 360 °, operating from a 220 V network. It can operate in a wide temperature range: from –10 to + 40 ° C. Suitable for large rooms, because the detection radius is up to 30 m.
• Camelion LX-28A 6438. Designed for indoor use. Mounted on the ceiling. The shutdown range is from 5 seconds to 9 minutes. What is important, the device is not expensive at all.
• Rev Ritter "Action" 110. Economical compact LED IR sensor. Mounted on a wall or ceiling. It works great and has an attractive price. However, the range is small.

A correctly selected and configured motion sensor guarantees energy savings and ease of use. Sensors can be used in the "smart home" system to turn on / off the light and as elements of a security system.