Proximity Switch: Purpose + Marking And Installation

Innovative ideas simplify many processes, add convenience to household and industrial equipment and automate work cycles.

Often a contactless switch that can react in time to a specific stimulus without human physical presence is used.

Let us have a closer look at what this device is and what it serves.

What is the article content:

  • What does a contactless switch serve?
    • How the device works
    • The application field of the proximity switch
  • What does the marking tell you?
  • Hands-on connection details
  • Home assembly
  • Conclusions and a helpful video on the subject

What is the purpose of the proximity switch?

To perform a certain action, it is not necessary to take an active part yourself - to go to the intended object and perform any manipulation with it. The smart product offered by the manufacturers of electrical equipment can partially replace a person.

The principle of operation of the equipment

The device that stops the operation of certain equipment in a non-contact way is called a switch or abbreviated VB. It is also often called a sensor - but this term also includes devices with an analogue output signal.

This terminology as well as the scope of use, the resistance to all kinds of damages and the technical specifications are defined in GOST R 50030.5.2-99. The document regulates the compliance of operating parameters, timely actuation of the protective mechanism in case of overload and other operational nuances of the device.

The product is a semiconductor element that controls the electrical circuit. When it detects a stimulus or its presence in its area of operation, it disconnects the load current, causing the circuit to open.

The fixture has a robust housing made of polymer or nickel-plated brass. Inside this enclosure is the electrical part that needs to be insulated. Many models have an IP65 or 67 protection rating.

Proximity switch: purpose + marking and installation

The construction of the product implies detection of an object or an object entering the active zone. This information is converted and transmitted to the switching unit

The device works without contact and the sensor, also called the photodetector, can be separate from or in the same housing as the transmitter.

The size, shape and appearance of the UBs vary according to the intended use, the fields of application and the conditions of use.

In the standard the shape of the housing is :

  • rectangular with square or rectangular cross section, designated as D or C respectively;
  • cylindrical with or without threading - A or B.

Depending on the model and application, the product can be equipped with an additional double-insulated wire.

For difficult conditions the non-contacting devices have a body filled with a compound. This is a polymer substance that provides reliable protection against the ingress of moisture and other foreign matter on the working mechanisms.

The devices are divided into 4 broad groups according to their operating principle.

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Inductive proximity switch

Empulsive proximity switch type

Inductive proximity switch

Photoelectric proximity switch

Empulsive and inductive detection is the more reliable method, and the UBs themselves, working in this way, are more durable than their counterparts. The former responds to an object made of almost any material, while the latter responds to metal.

Sphere of application of the non-contact device

The unique property of operating devices without directly contacting them opens up a rainbow of prospects for applications of this type of switch. It makes it possible to create original developments in various fields, to improve the living conditions in the house/apartment.

Proximity switch: purpose + marking and installation

Turning off the light without the owner making contact with the housing or other elements of the switching device is a reality. For the product to execute this command, it is sufficient to place the hand in the affected area

And for the sonic modifications, a clap of the hand is enough for the device, hidden inside the chandelier housing, to open the electrical circuit.

In addition, non-contact sensors are universally used to optimize production processes. They are used to monitor the quality of complex cycles in mechanical engineering.

And in automatic lines in the production of food and textile products, in the production of parts in foundries, and so on.

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Huge production areas with heavy equipment can work smoothly by monitoring processes with switches that will shut off the load in time if an error or overload occurs

Radio enthusiasts who invent robotics and think about automating many activities They often use non-contact sensors, installing them in their designs

In the manufacture of products on forging equipment, foundry machines or automatic lines, where the human eye cannot keep track of every element, it is also impossible to do without a reliable WB

In the home - to improve the quality of life at home. This is the power cut to the hand dryer, the light in the hallway, the fan in the bathroom, boiler

contact switches in mechanical engineering

Proximity switches in robotics

contact switches on automatic lines

contact sensors in the home

what does the marking tell you?

Proximity switches are supplied to the market by a variety of manufacturers. These include Western, domestic and Chinese companies. It is important when buying to pay special attention to the quality of the units and the reputation of the manufacturing company.

Due to the seriousness of the regulated processes for controlling which various modifications of the sensors are used, one should only choose products that have accompanying documentation - instructions with installation diagrams, operating conditions and a list of technical parameters.

Proximity switch: purpose + marking and installation

On the housing of the device itself, manufacturers indicate its characteristics as a set of letters and numbers - markings. Among these markings are encoded some of the important information on which one is guided when choosing the right model

Not all the indicators can fit in a small section of the switch. The others that matter to the consumer are in the user's manual.

If the model you like does not have a manual included, you should not buy it - it could be a fake. Moreover, some of the necessary parameters will remain unknown and the seller should not be trusted.

Proximity switch: purpose + marking and installation

All manufacturers are obliged to provide the final consumer with technical specifications. This requirement is spelled out in part 5-2 of the state standard for low-voltage non-contact equipment mentioned above

Each company producing switching devices for circuit control has its own designation system. Its deciphering is given in the catalog, which also contains the range of products offered.

Proximity switch: purpose + marking and installation

Example of marking of products from the company AS Energy. The other parameters of the models can be found in the manual supplied

The need for marking is not accidental - the variety of switches is great. Moreover, they can be classified according to different principles.

For example, according to the switching function the devices are divided in the following categories:

  • off switch (NO) - A;
  • off switch (NF) - B;
  • switching - C;
  • programmable version - P;
  • other - S.

And according to the installation method, the sensors are recessed, non recessed and others.

Proximity switch: purpose + marking and installation

Sometimes manufacturers prefer to indicate a long code describing a maximum number of product parameters, including sensor location, indication, climate design and others

If the company uses the marking principle recommended by GOST, the inscription on the switch would look like this

U3 A30 A D2


  • U means ultrasonic irritant detection. The others correspond to other Latin letters: I - inductive, C - capacitive, D, R and T - photoelectric direct, reflective and barrier, respectively;
  • 3 - installation method other;
  • A30 - shape and diameter, which in this case means cylindrical with a thread diameter of 30 mm;
  • A - element switching function, which means on (NO);
  • D - number of wires for DC or AC output, which corresponds to two connectors for DC;
  • 2 - plug-in connection method.

There are a total of 4 connection options, among which one corresponds to ribbon wires, two is considered above, three to a clamp and four to another method.

Proximity switch: purpose + marking and installation

In modifications that involve a wire, the manufacturer puts the characteristics on a label which is attached directly to the cable. It may also indicate the protection degree, recommended voltage and others

Conscientious manufacturers include Sensor/Sesor ZAO, German firm Fotoelektrik Pauly, NPK TEKO, PKF STRUS, ZAO Meandr, companies OVEN and SKB IS, NPP PRIZMA from Ekaterinburg and others.

Many of them offer a bespoke service to build light switches according to customer requirements.

We also recommend to read our other article where we described different types of light switches in detail. Read more here.

Individual connection details

Install a light switch for household use that functions without contact by yourself. As for the models for controlling the load current in industry, only a qualified person allowed to install them is allowed.

Proximity switch: purpose + marking and installation

The purchase must be carefully examined - the switch is supplied with instructions, fixing parts, sometimes with locking nuts. All these things must be connected

Before connecting the appliance, attention must be paid to the following points:

  • The power supply used for the proximity switch must correspond to the parameters indicated in the switch's certificate;
  • when tightening the fittings it is important not to overtighten the nuts.

The manual should include a wiring diagram to follow and the method of installation for the particular model.

Proximity switch: purpose + marking and installation

The installation options depend entirely on the specific characteristics of the variant purchased. It is important to use the particular method typical of the probe purchased

First of all, the mechanical installation is carried out using fasteners, locking nuts if necessary, to connect the instrument.

When everything is firmly fixed, it is time to proceed to the second stage: electrical connection.

Proximity switch: purpose + marking and installation

The wiring scheme depends on whether direct or alternating current is used. The number of wires also affects the choice of circuit - here you must be careful to correctly connect the existing cables

When working on the mains it is important not to forget to switch off the power at the apartment panel in order to protect yourself. The VB wire is then connected in one of the ways required by GOST. Its type depends on the modification.

Most often for domestic use buy a sensor that controls the chandelier. Therefore, the last step is to place the device in the body of the lighting product. If necessary, adjust and set the response time, the active distance at which the device will operate.

Assembling the device at home

It is possible to make the switch yourself. Although at first glance this endeavor seems complicated and incomprehensible to the average consumer, it will work if you choose a simple way.

The best part is that a person who does not have much experience in assembling electrical devices, but is vividly interested in such units, will be able to cope with the task.

Of course, if one does not aim at making a device capable of making programmable switching of an element - when complex response options are realized.

Proximity switch: purpose + marking and installation

The simplest option is to make a switch which detects an object a few centimeters away and opens the contact at that moment. This could be control of a light bulb, a fan or other apparatus

The device should be able to switch off the light bulb if the user's hand touches it for a couple of seconds.

First the working elements for the construction must be prepared. This will be the board, the IC, the transistors, the relays, the capacitors, the LEDs, the photocells and other accessories.

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A good option is to buy a ready made set of components so as not to assemble in the market piece by piece. Especially since the Chinese sell quite inexpensive

Take the schematic that comes with the parts, examine it carefully and put each of the parts in its allotted place

Each element inserted on the board has legs that are much longer than the required length. Therefore it is better to bite and bend the ends on the back side. Otherwise, it is advisable to practice on a rough draft and then solder each connection

Finishing part of the job, you need to put the remaining LEDs, capacitors and other parts in the places assigned to them. On the board you can see the markings

It is the turn to put the relays, following the recommendations given in the layout of the components of the assembled construction. Carefully solder

In the area of the board designated as RX (receiver), set the photodiode, covered with plexiglass black. And on the part labeled TX (transmitter) - a transparent LED. In these parts the longer pin is responsible for the plus

Now the chip is placed on the rectangle which is specified in the manual. With the help of a soldering iron it is fixed firmly,

A good variant is to buy a ready made set of elements

Bend the ends of the element stems

Solder each connectors

Place the remaining parts

Place and solder the relay

Install the photodiode and the LED

After soldering you must check the quality of the connections made, that each element of the assembly has been firmly fixed.

This is the lifespan of the product as it is to be placed inside a fan, a hand dryer or a chandelier.

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The main thing is not to make a mistake when inserting the microchip: you have to study carefully its location in the instructions

The non-contact device needs electricity. Therefore, it is necessary to connect the power supply to the board, without mixing up the plus and minus contact on it

Finished assembling and soldering, you can conduct testing. To do this, check the operation of the switch by passing a hand over the design - should light up the indicators

You can adjust the delay time off, reducing or increasing it as you wish, or the range of response to a stimulus

To add a little functionality, you must buy another chip, for example, CD4013BE or any other series 4013. It is better not to get a domestic one, giving preference to a foreign one. You also need one 10 kOhm resistor/resistor

Now you have to solder the resistor and then connect the plus and minus wire and a 10 kOhm resistor to pin number 13 for the output

After you have carefully looked at the circuit diagram,

The wire from pin 14 should go to the plus marked earlier, and from pin 7 goes the negative wire, which should also be soldered. This is indicated in the instructions of the chip

The main thing is not to confuse the keys, is to avoid mixing up the keys when inserting the microcircuit

connecting the power supply to the board

Checking the function

Adjusting the response time

Another microcircuit CD4013BE

Soldered the 10K resistor to the IC

Finding the plus and minus on the board

Solder the plus and minus wire to the board

It is necessary to test if the assembled device works. In order to do this, carry out some actuation tests by passing the sensor close to the palm of the hand.

Proximity switch: purpose + marking and installation

If the result is satisfactory and the design passed the test, it can be placed in the housing of a lamp, chandelier, drier or similar and connected according to the circuit

When the result is not satisfactory, the adjustment screw must be used to set the necessary parameters to react.

The assembled switch can be further modified by adding the desired functions if you have wiring experience and a wish to create something original.

Conclusion and useful video on the subject

Why do you need a proximity switch, its types, connection and marking:

The infrared switch helps you turn on the light without touching the real keys of the switching device. Assembly and demonstration of its operation in the video:

A clever non-contact type fixture can be used for automatic drying. About this in the video:

Capacitive switches that actuate without direct contact to the object:

Finding out the subtleties of marking and the application range of specific types of sensors, the optimal model for switching an electric circuit can be selected. Or, in fact, to make a contactless unit with their own hands, having purchased a set of necessary elements with a scheme for their location. Such a switch will allow you to make your home a little \"smarter\".

Would you like to ask a question about the installation of a proximity switch? Please leave comments in the box below. Here you also have the opportunity to report an interesting fact on the topic of the article.


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