Most often, cam switches are used to switch electrical circuits, in particular to control electric motors. In this article we will introduce you to the main features of this device, telling you how it works, what it consists of and why it is needed at all. Photo and video examples will allow you to learn even more about the device, operating principle and purpose of cam switches.

What it is?

Cam switches (pictured below) are electrical devices that are needed for switching in electrical circuits, both AC and direct current. They have found application for switching power circuits for controlling equipment, as well as in the operational control circuit for other electrical devices. The devices can be used in low-voltage circuits and in circuits with voltages up to 500 V - for alternating current (frequency 50-60 Hz) and up to 220 V DC.

They are made from insulating and conductive materials High Quality, and were created using successful experience in creating modern technology, as well as knowledge gained in the process of developing switching devices. Cam switches are characterized by their small size, they are resistant to short-term overloads in the circuit, and also have good switching capabilities. To protect them from current short circuits in the electrical circuit you need to use fuses with fusible links.

Design

From the very name of this device it is clear that the design is due to the use of “cams”, which drive a kind of “pusher”. The design of a cam switch assumes the presence of a group of switching elements, by changing the position of which it is possible to achieve a certain arrangement for the operation of different switching circuits. The arrangement of contacts and cams is called a switching program (its purpose is to assemble a specific connection diagram). They are located inside a plastic case, which is made on the basis of melamine.

You can clearly see the design of the device in the diagrams below:

Such a housing is immune to electric arcs and eddy currents. The design of the cam switch makes it possible to turn all contacts on and off almost simultaneously. This is ensured by the fact that the cam of one element is mechanically connected to other cams. The use of silver in contact devices, which better than that one the same copper can withstand electric arc, provides good switching characteristics and increased wear resistance. The switch must be clearly fixed in a certain position, for which a drive locking mechanism is needed. The design also includes a drive motion limiter. Its purpose is to clearly set the switch in the extreme position. The drive or shaft of the apparatus is a square rod. For reliable operation and good contact switching, it must be made of metal to withstand the stress of cranking. This is very important where motor control is used. To control the switch drive, a handle made of insulating material is used.

The design of a cam switch is clearly demonstrated in a video from one of the ABB companies:

Principle of operation

The principle of operation of a cam switch is based on the inclusion of a certain group of contacts by rotating the drive of the device. By rotating the handle to the desired position, the drive rotates around its axis and actuates the cams located on it. They, in turn, close a certain group of contacts. To understand how a contact group works, you need to look at the inclusion diagram, which is compiled based on necessary scheme connections. When the drive is in the desired position, the switch is fixed in it using a special locking mechanism and the circuit begins its operation. To return to the zero position, you must turn the handle again. According to the principle of operation, they are divided into switches with automatic return of the handle to the position and manual.

Purpose

A cam switch is needed for:

• control of mechanisms that are driven by three-phase and single-phase motors, to change the connection of the windings of alternating current motors (star-delta), change the direction of rotation;
• control and signaling in operational circuits;
• can work as a switch, switch for operating positions of an electric welding machine;
• switching the required connection of the resistance group;
• ensuring switching of operating modes of heating equipment;
• turning on and off the drive of the sectional disconnector mechanism in transformer substations.

Today, much attention is paid to lighting, because indoor comfort most often depends on it. But you should not treat it wastefully; economy, as they say, comes first. But imagine a situation with a long corridor. You enter it, turn on the light, reach the end of the corridor, but you cannot turn off the lamps. And until you return back, this cannot be done. Or, conversely, you enter a dark corridor, and the switch (switch) is located at the other end of the room. We'll have to walk in the dark. What to do? There is only one way out - install a pass-through switch (the connection diagram will be discussed here).

Connection diagram

What will be needed for this? Basically, except for two pass-through switches and a little wire, nothing. The pass-through switch has three contacts and two switching positions. But keep in mind that the changeover mode should be like this: one contact in two positions is common, and two are different. That is, it turns out that in one position it is closed with one of the two contacts, and in the other with the other. Moreover, it is one hundred percent that three contacts cannot be closed at the same time. By the way, here is this simple diagram in the figure:

Please note that only the phase circuit passes through this switch, as, in principle, when connecting any other devices of this type. For example, a regular switch is also connected. And the zero circuit goes directly to the light source. But at the same time, all contacts are connected to each other only through a junction box. And this connection turns out to be a pair, that is, the common contact of one switch with the common contact of the second. The same goes for switched contacts.

Please note that cables with three cores come out of pass-through switches, and two-core wires come out of lamps.

Sometimes there is a need to install pass-through switches in three places, for example, on a flight of stairs on three floors at once. In principle, the assembled circuit of the pass-through switch is almost the same here. Here it is in the picture below:

Everything is quite simple, the only thing you need to pay attention to is the third pass-through switch. In fact, this is a kind of paired switch, that is, when you press a key, it immediately turns off the other two devices according to the principle of disconnecting two contacts inside the structure that are not connected to each other. In this case, four wires should come out of this switch, that is, this device is a four-pin device with two inputs and two outputs. This type is called crossover.

It should be noted that these types of pass-through switches have the most simple design, which is a big plus. But they also have a disadvantage - a limited number of control points, due to the fact that it will be difficult to switch a large number of wires in one place.

Types of pass-through switches

The two schemes described above are the simplest, therefore they are equipped with single or, as electricians also call them, single-key switches. They have two exits and one entrance. By the way, it should be noted that the manufacturers made sure that the electrical installer did not mix up the contact ends. Inside there is a connection diagram for the pass-through switch, which is printed on the case. So it will be quite difficult to make a mistake.

But, in principle, it is already clear that the phase wire connected to pass-through switch, must come out of the junction box and connect to the input. The remaining two contacts are outputs, which are also output through a junction box to another switch and, accordingly, to the light source. Here is a simple wiring diagram.

There is a more complex connection diagram for a pass-through device. It also requires controlling lamps from different places, but the number of groups of lighting fixtures may be different. That is, there is a need to control different groups of lamps from different places. This will be more accurate. To be completely specific, then, for example, you have a chandelier with five light bulbs in your living room. You need to install two switches: one in the living room itself, the second in the hallway. But at the same time, you need to make sure that you can turn on three light bulbs separately, and two separately. When there is only one switch in the living room, this is easy to do. What to do with two pass-through switches?

So that you can immediately understand, here is a diagram of such a connection:

It clearly shows that different groups have different numbers of light bulbs. Please note that the number of light sources can be changed in different groups at your discretion.

In this scheme, as in the first, there are two pass-through elements, each of which has two keys. Hence the different design from the previous one. It has two inputs and four outputs, that is, six contacts. If you take a closer look, you can understand that these are, in fact, two single-key pass-through switches in one housing. The cross variety has already been mentioned above.

What is the difference between a pass-through switch and a regular switch?

To answer the question posed, it is necessary to consider the connection diagrams of these devices. Here they are in the picture below:

Here you can clearly see how the devices differ from each other. And yet the main difference is the operating principle itself, when the electrical circuit is opened. IN in this case It doesn’t matter here how many keys are present in the device. Look at the diagrams, in them a regular switch simply opens the circuit. A switch on one side breaks one circuit and immediately closes the other. In addition, this second circuit is the contact of the second installed switch. And the reason here is that these elements do not work alone, only in pairs with exactly the same device.

Attention! A pass-through switch can be installed instead regular switch, it will perform the same functions. Just one of the two moving contacts will not need to be used and connected.

Of course, if you put some effort into it, you can do it from the usual two-gang switch make a pass-through switch. Practice shows that this is not a problem either. But there is no point in doing this today, because there is no shortage of this type of equipment.

Conclusion on the topic

So, we have analyzed the connection diagram pass-through switch(and more than one) where they were shown different variants And various devices from this category. Having received complete information, you can understand why this electrical element is good and what its functions are. In conditions of increasing living comfort, switches are increasingly finding their consumers. They are used not only in long corridors and stairwells; increasingly, devices are installed in large halls and halls.

Switches electromechanical ones are used in radio electronics for switching electrical circuits of direct and alternating voltage. The oldest types of switches are toggle switches, the pioneers of which are domestic manufacturers. A reliable mechanical spring-lever device ensures rigid adhesion of the contact group, which directly affects the quality actuator. Some of them include models TP1-2, TV2-1V, PT24, PT26-1. Toggle switches from foreign companies are not inferior in quality and parameters Jietong Switch series product line KN 3.

Electromechanical rotary switches include biscuits switches. The biscuits switch consists of a biscuits with a contact group, and a rotor axis with a movable plate switch. Biscuit switches differ in their parameters: number of positions (positions), number of contact groups, sections (biscuit), body length. These characteristics must be used as a guide to select the appropriate component. Roll type switches are used in a variety of applications. measuring instruments for switching ranges of measurement limits, in automation systems, electrical control circuits, switching voltage ranges in power supplies, switching low-frequency signals in audio equipment. Popular and inexpensive product models today include the company’s switches Well Buying that are in demand in the consumer market. They have more high-tech quality and parameters biscuits switches from Russian factories, such as, P2G3, PG2, made in sealed housings and with a high working life.

Keyboards (rocker) switches are a type of electronic-mechanical network switches that are successfully used in a huge variety of electronic equipment. Key switches are divided according to basic parameters. The name of the product, its colorful photo indicating all sizes will help you easily select the appropriate component. In addition to this, you can familiarize yourself with the main characteristics. Operating voltage and permissible current determine the installation of the product in a structure of appropriate power. The number of pairs of a group of contacts determines the number of switched circuits of the device. Most of the products offered have a backlight at the end of the device. For example, automotive power switches series A.S.W. companies Jietong Switch equipped LED backlight, indication of household series switches IRS carried out with neon lamps. Structurally made of durable plastic, the products are securely fixed in the mounting socket, the connection is carried out both using contact terminals and by reliable soldering.

End switches belong to the group electrical appliances, interacting a movable mechanical lever with a group of switching contacts. The main application of these components is automated industrial control systems for moving structures. The company's products are characterized by reliability in performance Honeywell And Cirmaker. These components are made from high strength material with a roller mechanism of a moving element, are characterized by a high switching current and ease of installation on a working panel.

Famous production company "MEGA-K" presents a line of highly efficient inductive switches. Inductive proximity switches used as sensors for monitoring the position of metal objects. Particular applications are industrial machines and automated lines. The selection of the required product is carried out according to such parameters as response distance (mm), device connection circuit, for example, type of output switch PNP transistor, installation method, for example, in a hole for a nut.

The category of switching microcomponents of modern electronics includes DIP switches, used for switching and switching low-current control circuits in computer devices, office equipment, household appliances. Structurally, DIP switches are made in monolithic housings with one or more contact groups, angular or horizontal slide switching. The price of the product depends on the parameters of the switch, as well as on the manufacturer.

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You can buy products from the “Switches” group wholesale and retail.

Where to place the switch? This is a difficult question if you need to turn the lights on and off in a large room with several entrances, or in a long corridor. If there is only one switch and there is a lot of space, this is inconvenient.

Is it possible to do better - to turn the lights on and off from different ends of the corridor or staircase in the entrance, in the local area from the house, garage, from the gate, and so on? In our digital age, radio-controlled remote controls, motion sensors, etc. immediately come to mind. This is great, but it can be done simpler, cheaper and more convenient. You just need to use a pass-through switch.

Many of us have come across a circuit of a pass-through switch in a school problem book. The problem for the seventh grade suggests creating a diagram in which you can turn on and off a light bulb at either end of the corridor. To understand the operating principle of a pass-through switch, let’s look at the solution to this simple problem.

First, a simple diagram of “one light bulb and one switch”:

Key K1 is closed, the light is on. If you open the contacts, the lamp will go out. Using such devices, the problem of turning on and off from different ends of the corridor cannot be solved: even if we can turn on the light with different switches, we will not be able to turn it off just as easily.

Pair of pass-through switches

To solve the problem, you need not switches, but switches, and you also need an additional wire. The switch transmits voltage to one of two wires:

Here the phase is transferred from pin 1 to 2. If you click the switch, the voltage from pin 1 will flow to 3.

In any position of the switch, only one of the wires will be energized: 2 or 3.

That's what it is electrical diagram pass-through switch: simple switch.

But for operation you need at least one more walk-through light switch. You need to run two wires to it from the first switch.

What happens if we click switch 1? The circuit will open. What if there is switch 2? The same.

This means that the light can be turned off from either end of the corridor. And after that, you can turn it on by clicking any of the switches. For example, first:

The single-key pass-through switch does not have On or Off positions. Any switching of one of the pair of switches changes the state of the system: if the light was on, it will go out, and if it was turned off, it will light up.

What to buy to implement the scheme

Understanding how a pass-through switch works, you can independently install a convenient lighting control circuit. Products from several companies are popular on the electrical goods market, for example legrand pass-through switches. They are functional, have an attractive design, some with LED backlighting.

The legrand valena pass-through switch, if it is without a pair, can work as a simple one. But usually they are bought in pairs.

Buyers often ask how a pass-through switch looks different from a regular one. There are few differences: enterprises use a single housing design for different devices. There is no marking on the pass-throughs indicating switching on (sometimes there is one, due to the use of standard components, but they do not pay attention to it). Differences in the connection of electrical contacts can be easily determined by a person familiar with electrical engineering.

The figure shows the connection of a pair of legrand pass-through switches operating for one group of lamps.

Pass-through switches, like regular ones, are available with one or two keys. Two-key controls control two groups of lamps. You can, for example, adjust the brightness of the lighting by turning on and off groups of light bulbs in a chandelier.

No worse than products from other companies: lezard, lexman, abb, schneider electric.

Lezard pass-through switches are connected in the same way as those made by legrand and other companies.

It is very simple to assemble a circuit from devices from any manufacturer, but sometimes difficulties arise because circuits with errors are found on commercial sites on the Internet. Sometimes cheap Chinese devices are accompanied by paper instructions with errors in the circuits.

Use it the simplest scheme, in which everything is clear, which you understand.

Turning lights on and off from ten places

We examined in detail the switching scheme for lamps from two different places.

But is it possible to make the light turn on and off from three, four places, and so on? For example, when leaving an apartment, on any floor, turn on the light on the stairs, and when leaving the entrance, turn it off. And do the same in reverse order: turn on the light when entering the entrance, and turn it off at your door. Or late at night, leaving the office into the corridor, where the zealous caretaker has already turned off the light, do not wander in the dark, but flip the switch at your door, let there be light! And then turn it off on the way out. And there should be several such switches in the corridor - at different doors.

To organize such lighting, you need to use more complex pass-through switches, they are called cross switches. Let's consider their functioning.

A crossover switch is something that has two input terminals and two output terminals. A phase comes to one input, an empty wire to the other, in random order.

Accordingly, at the outputs we have: on one - phase, on the other - nothing. By clicking the cross switch key, we will reverse the phase and “blank” on the output terminals.

If you place a crossover switch between two pass-through switches, you get three switching points. Each switch, if you change its state, changes the lighting: if the light was on, it will go out, and if it was off, it will turn on.

Look at the picture. At the moment the circuit is closed, but what happens if you click any of the three devices? The circuit between the input and output will open and the light will go out.

Interestingly, after turning off, we can turn on the light, again by clicking ANY switch.

You can put two cross switches, three, four... in the middle of the circuit. no matter how much it’s a pity. And any switch will change the state of the system.

This may seem surprising, especially since a long chain of switches can be difficult to understand. But nevertheless the scheme works! After all, no matter the position of the switching devices, the phase is not “lost” - it comes to one of the two outputs of each cross-switch, and only the last pass-through “selects” the phase or its absence.

Clip-on crossover switches are in demand

Pass-through switches are produced in the same housings as conventional ones. There are overhead and built-in models, in versions for internal and external wiring. Overhead models of pass-through and crossover switches are in demand because they are in large quantities used to improve lighting systems, including outdoor lighting.

When building your home, a convenient switching system with pass-through switches can be included in the electrical wiring project.

New technologies: touch pass-through switches

Stylish touch switches are more expensive than regular ones, but are in demand - they have become a natural part of modern “digital culture”.

Touch devices are quite complex electronic devices. A thyristor or transistor is used to switch current high power, and the signal that opens (or locks) the device comes from a sensor - a sensor that responds to any external influence.

The sensor can be a motion sensor, or acoustic, or capacitive - responsive to touch. Sensitive sensors react even before touching, just bring your hand to a distance of 1-3 centimeters. Homes usually install capacitive touch switches, or those combined with a motion sensor. All touch devices can be controlled remotely. If the control panel is not included, it must be purchased separately.

The semiconductor device responsible for turning the current on and off can also be used to control the current strength and brightness of the light, if equipped with a dimmer. It is important to know that dimmers are not suitable for all lighting fixtures.

Pass-through and cross touch switches, like mechanical ones, are used to control lighting fixtures from different points. Compared to mechanical ones, they are more functional: they can be controlled remotely and control the light intensity.

Externally, touch devices are a smooth glass panel; when connected, there is a visible indication on it: blue firefly - OFF, red - ON. For driving lighting device you just need to touch the device panel.

The photo shows a touch switch.

The paradox is that technologically advanced sensor devices do an excellent job of controlling incandescent or gas-discharge lamps, but problems arise when turning on advanced LED lamps. In the circuit “touch switch - LED lamp» in the off state, weak electrical impulses can be induced, due to which the LEDs “wink”. Sometimes there are problems with the dimmer if it regulates the current through the LEDs.

The figure shows a diagram of connecting the adapter in parallel with the LED lamp.

In this picture, the adapter is connected to the junction box and affects all LEDs included in this circuit.

Let's look at the connection diagrams for pass-through touch switches.

This shows the connection of two touch pass-through switches.

Shown here is the connection of three feedthroughs touch switches.

Note that in the middle there is the same touch switch as at the edges. That is, touch devices are not divided into “simple” and “cross”.

In the chain of touch switches there is a “main” one - which is shown on the left; three wires go to it (one wire is from the load). Before starting work, the system must be synchronized. Touch the panel of the main device and wait for a beep for 5 seconds. After this, you need to touch the second switch. Synchronization completed. Next, the third, fourth, and so on are synchronized with the main switch.

Pass-through socket - it's very simple

Having become familiar with the remarkable properties of walk-through switches, we expect miracles from such an object as a walk-through socket. But there's nothing special here. There is simply an end socket (electrical wires that go to it that don’t go anywhere else) and a pass-through socket - it is connected to the wiring, to which several more sockets are connected.

Pass-through sockets have neither design nor circuit features. The name simply reflects their place in the electrical supply system.

What limits the number of pass-through switches

A chain of switches that allows switching electric current from several points should not be too cumbersome. Contacts offer resistance electric current. It is small, but over a long chain of contacts the current can decrease noticeably. At large number switches connected one after another reduces the reliability of the circuit, and failures are possible. Therefore, we rarely see a string of pass-through and crossover switches of ten or more pieces. Most often this is a pair of switches, somewhat less often - a chain of three, four, five.

Using these devices makes life more convenient and saves energy.

Types of pass-through switches

So, we looked at different options for this class of devices. In conclusion, we list their types.

By technology:

• mechanical;
• semiconductor (touch, with remote control).

By the number of independent loads:

• single-line;
• multi-line (for 2, 3 groups of lamps).

In addition, mechanical switches come in two types:

• simple checkpoints;
• cross.

Connecting pass-through switches is very simple. Good luck!

Video on the topic