What types of light switches are there? All types of switches for home use - what they are and where they are used Types of television sockets

Special devices are required to break and connect electrical circuits. Such devices are switches. They come in various designs, depending on the purpose, operating conditions, switching voltage and current. In general, this is not a very complex device, but quite responsible. Let's look at what types of switches there are.

For each application area, the industry produces its own types of switches; all of them can be divided into several groups according to different characteristics. Switches are divided by type. Each type has its own area of application. You can also divide switches by control method.

There are switches with manual control, there are those that are controlled by parts of mechanisms (limit switch) or the physical environment in which they are located (gas relays, thermal relays, etc.), and there are switches with electric drive. In the latter case, most often we are talking about a relay and magnetic starters, but there are precisely switches that are called just that: oil or air for high-voltage powerful circuits in the energy sector.

Switches and sockets, like all other electrical equipment, are divided according to the conditions of use ( climatic version). Nowadays the international protection system (IP) is widely used. These letters are followed by two numbers and an optional letter.

The first digit means the protection of the product from getting into it foreign objects from outside. These objects have any size, up to the size of dust particles. The second number indicates the degree of protection from moisture. The higher the numbers, the higher the degree of protection.

Materials used in switches

Two types of materials are used to make switches. The first is conductive, which must meet the requirements of high corrosion resistance and low electrical resistance, and the second is insulation. Here, on the contrary, the resistance should be as high as possible, and heat and chemical resistance should also be high. Mechanical strength is also very important, since sometimes increased forces are applied to the switches.

For live parts in switches, brass, copper, and bronze are used. These materials are corrosion resistant and have low resistance. Contact surfaces are often soldered with alloys containing precious metals: silver, gold, platinum, rhodium. This increases the service life (time between failures) of the circuit breaker. Cheap models use simple copper soldering with alloying additives.

The base and moving insulating parts are made of heat-resistant and low-flammable plastics with mineral fillers. The fact is that with the passage of significant currents and increased transition resistance in the contacts, the switch begins to heat up and this heat should not damage its design. In high-power switches they use ceramic materials, and asbestos. Switch housings are made from various materials, depending on the execution.

Switches for home (domestic use)

Various types of switches are used in everyday life, but their purpose is usually limited to controlling lamps. Such a switch should be convenient, safe, and have an attractive design. According to the installation method, it can be built-in or installed externally. Nowadays, rotary keys are used as controls; such switches are common in Europe.

In the USA, almost all switches are lever-type (toggle switches), apparently, a tradition. Even earlier, rotary switches were used, an invention of Thomas Edison. They were common throughout the world in the first half of the 20th century and switched up to several circuits in 3–4 positions (batch switch). Package switches are still used in many old utility panels.

To turn on lamps, a single-key switch is used; for chandeliers, a two-key switch or even a three-key switch is used. Double switch Lights are also often used for a pair of toilet/bathroom rooms. It must be said that modern sources lights are quite advanced compared to what they were 15 years ago. Therefore, many switches with additional functions have appeared. The simplest of them is a backlit switch for night time.

A switch with a shutdown timer is used to save light when not in use. large rooms(closets, bathrooms) where they enter for a short time and forget to turn off the lights.

The switch with a dimmer can be used with those luminaires that support the dimmer function. Sometimes they are included in the kit, since this type of device has not yet been standardized.

A light switch with a motion sensor is another way to save electricity and is very convenient. The light turns on if infrared sensor detects human movement in the sensor's field of view. Repeated motion may turn off the lights, or a timer may do so after motion has been detected. A switch with a motion sensor does not require any action from a person; his presence is sufficient.

There are quite exotic look– clap switch. Inside it there is a microphone, an amplifier and a microprocessor device for recognizing the nature of the sound. Such a switch, after installation, may not work the first time, since it stores the sound from the user in memory for later comparison. I must say frankly that this is a rather stupid way to turn the light on and off - people may already be asleep and the noise will disturb them.

The floor switch is made in the form of a button with a locking mechanism. It is designed for a small pressing force and is structurally designed in such a way that it is not damaged by large weights and can withstand the weight of the leg.

The ceiling switch is also a button with a lock, to which the force is transmitted from a lever with a cord attached to it. The mechanics are hidden behind a decorative cover. To use such a switch, turn it on or off, you need to pull the cord or tug it lightly.

Designation of switches on construction diagrams

One of the circuits used by electrical builders is not fundamentally electrical. This is the layout diagram. It is carried out according to its own rules and has different circuit diagrams designations.

Sometimes consumers need to agree on a project, as customers they have every right to do so. They are shown a diagram that is difficult for them to understand and they often accept it as is, and then fiddle with modifications. Below is the designation of sockets and switches in the drawings.

The designation of switches in the drawings is indicated by a small circle from which a segment emanates at an angle of approximately 60° to the horizontal. An open installation switch is indicated by a short dash to the right, set aside from the end of the segment. The number of such dashes indicates the number of poles. Number independent switches in the group is shown by repeating vertical segments shifted by an angle of 30°: a four-key switch will be depicted by four segments, a triple switch by three, etc.

Rosettes are indicated by a semicircle convex upward (usually a segment of a circle). As many segments are laid off from the circle as there are poles in the socket. If the socket has a terminal for protective earth, then a horizontal tangent is drawn at the top point of the arc.

The pictures showed overhead sockets and switches. Hidden ones differ from them only by a vertical line in the circle segment (socket) and a T-shaped line instead of an L-shaped one at the switches. Outdoor sockets and switches designed for outdoor use are designated similarly to those shown, but they have a higher protection class: from IP44 to IP55, which respectively means: “no gaps of 1 mm or higher and protection from splashes in any direction " and "partial protection against dust and short-term protection against jets from any direction."

To distinguish such sockets in the drawings, as well as switches, they are filled with solid black color. All other notation rules remain the same. For more information on electrical symbols, see construction drawings please refer to GOST 21.614–88.

Today, a range of electrical products can provide the creation of any design solution and make indoor light control comfortable and enjoyable. To choose the right switch, it is necessary to take into account not only its functionality and beauty, but also the quality of workmanship, otherwise this may result in unpleasant consequences.

A switch is a special electrical device that serves to open and close electrical circuit using contacts. Therefore, first of all, when choosing, you need to look at technical specifications switch, and then on its external design for harmonious combination with the interior of the room.

Device

A simple single-key switch consists of the following elements:

Working mechanism.
Protective plastic elements.

The frame and key are protective elements. The key also switches on and off power to the circuit. Under the key there is a frame secured with plastic latches or two screws. Under the frame there is a working mechanism on which the key drive is located.

The working mechanism is fixed in the socket box using spacer tabs or special screws. There are two tabs on the sides of the switch. When screwing in the screws, the tabs move apart and rest against the socket box, fixing the switch mechanism. Typically a switch has two terminals. A phase is connected to one of them, and a zero to the other.

Types of switches

For domestic use, you can choose a switch of different designs. It refers to switching devices with two operating positions of contacts that open and close an electrical circuit.

Key switches have become classic. They are the most popular of all electrical devices and are often used to connect lighting devices. The principle of their operation is simple: when you press a key, the electrical circuit is closed. Most often, the case is mounted so that when the key is turned off, it is in the upper position. There are switches equipped with one, two or three keys.

Advantages:

Easy replacement, installation and repair.
Convenient to use.
Low cost.

Minor disadvantages compared to others include:

No energy saving properties.
Light intensity is not adjustable.
Short service life.

Pass-through types of switches used in large rooms where lighting control with different places. By appearance Such switches are no different from ordinary ones, but there are some design differences inside. Walk-through switches are usually used on stairs or in long corridors. You can turn the light off or on from different points.

Pushbutton switches have existed on the electrical devices market for a long time. They cost more classic models, and do not have great advantages. One can only note some originality of the buttons, combined with the design of the premises. There are switches with different numbers buttons, with decorative trim and LED indicator. Therefore, you can choose a switch for any design.

Touch switches are an innovative development. They have the longest service life and are convenient to use. Models of switches with touch control are used in the system in modern houses and apartments.

They operate by touching the surface of the finger. Many touch switches come with assistive features such as automatic shut-off. An important advantage of this type is that it will not cause short circuit, since the device has no mechanical contacts. This increases the safety of their use in domestic conditions.

Acoustic switches work from cotton with their hands. Many people like this feature of their action. In the dark, there is no need to search for a key, button or rope. The disadvantages of acoustic performance include the following factor: it often does not work the first time. However, this drawback occurs only in cheap product samples.

How to choose the right switch

The main criterion for choosing a switch is the type electrical wiring. For open wiring in own homes overhead switches are suitable. For hidden electrical wiring there are hidden species switches with a housing recessed into the wall. Before purchasing, you should inspect the switch and check the mobility of the key.

Sometimes sellers try to sell an expensive model or defective goods. Therefore, their recommendations should be treated with some criticism. It is better to listen to the advice of professionals, it will be ideal option select a switch.

A visual inspection is a prerequisite. This determines the quality of the material. The surface of the switch should be smooth and the lines should be clear. The plastic must be hard. Otherwise, the surface will quickly scratch and spoil the appearance.
The body must have the quality mark of Rostest or the manufacturer.
There should not be a sharp unpleasant odor coming from the body. This is a sign that plastic is unhealthy.
The weight of a switch can say a lot about its quality, since a product that is too light indicates that materials of insufficient thickness are used, which reduces the reliability of operation.
A quality product must be able to be disassembled small parts, have various fastening devices, latches, removable frame and other spare parts. The more parts on the latches, the better the quality of the plastic used for manufacturing.
If there are assembly instructions, then this is a positive factor that determines good quality.
The appearance of the product must be combined with the design of the room. Therefore, you can choose a switch with a colored frame or backlit keys.

All switches and switches are designed for one thing - in right time turn on or off (close or open contacts) lighting. They are designed for both open and hidden installation, and are also splash-proof for outdoor installation.
Depending on the principle of operation of the drive, they are rotary, reversible, one- and two-button, one-, two- and three-key, as well as ceiling-mounted with a tie cord. The mechanism of switches and switches must be reliable (with good contact, otherwise it will spark and overheat) and be operational. The performance of the mechanism is determined by the number of “on-off” cycles. Performance of 30 thousand cycles or more is considered high.

Pushbutton switches

Pushbutton switches are often used in various household appliances, lighting devices, in production, and therefore it is important to know the principle of their operation.
In addition to the button, the body contains a spring that returns the pressed button to its original position. Inside the button, a pusher in the form of a plate is attached to the axis, which, when the button is pressed, acts on one or another side of the movable contact, closing or opening the electrical circuit. The moving contact is mounted on an axis, which is fixed in the switch body. Two fixed contacts are connected to the break in one of the wire strands and are attached to the base of the switch.
The switches that are installed at the base of the table lamp have a slightly different design. To secure such a switch, its cylindrical part is passed through a hole in the base of the lamp, which is clamped between the washers by screwing on a plastic clip.
Protected and tinned wire strands are inserted into the contact holes in the switch body and clamped with screws.
Floor lamp and some household electrical appliances it is more convenient to turn on and off using floor switches with foot controlled. The switch is inserted into the base of the housing, and the wires are additionally secured with brackets.
A switch with a cylindrical pusher is installed on the wire of table lamps and other mobile devices. It is designed for a current of 1 A. The design of such a switch is simple. The cylindrical pusher has a metal rim, due to which the movable spring contacts are closed; they are connected to the break of one current-carrying wire, and the second wire passes through the switch body (Fig. 100).

Diagram of a cam mechanism with a reversible drive
The cam mechanism has end contacts, flat springs and a handle. When throwing the handle, a flat spring with a movable contact ensures a connection with a fixed one or an opening when operating in the reverse order.
This design is characterized by high performance (at least 150-180 thousand “on-off” cycles), stable contact pressure throughout the entire service life, silent operation, resistance to vibration and small overall dimensions. The disadvantage of this mechanism is the high degree of wear of the opening contacts (Fig. 101).

Key switches and switches

Keyboard devices may also have mechanisms various designs. For example, a double-arm swing mechanism with a compression spring. When you press a key, it rotates around its axis. The pusher (can be in the form of a ball or a semicircular cylinder) under the action of a spring presses on a swinging lever, at the end of which a movable contact is welded. When the key is deflected in one direction or another, the pusher, under the influence of a spring, presses on the moving contact swinging on the axis, closing or opening it with the fixed contact (Fig. 102).

The advantage of such a mechanism is that it high efficiency(up to 200-500 thousand “on-off” cycles), instant shutdown, stability of contact pressure throughout the entire service life, small dimensions and weight of the switch, the ability to switch in the “on” position, that is, one of the contacts in it is always closed. It is not suitable for controlling a chandelier, since it cannot be turned off. Such switches are used to control lighting from two points. For example, install one switch P-1 at the beginning of a long corridor or on the 1st floor of a two-story house, and the second - P-2 - at the end of the corridor or on the 2nd floor. Entering the house, turn on the lighting with switch P-1, and when going up to the second floor, turn off the light with switch P-2. Going down from the second floor, turn on the light with switch P-2, and turn it off on the first floor with switch P-1 (Fig. 103).

How to install a three-key switch.

For open installation, a switch is produced with a mounting base, which is fixed to the wall with two screws. The switch body is screwed to it with two screws. In order to insert electrical wires inside the switch, you need to break out the under-pressure in the mounting base (a section with more thin layer plastic than at the very base).
For hidden installation, switches are produced with spacer legs, which, resting against the walls of the box (glass), securely fix the switch.
Each key has a metal plug. The plug fits into the grooves of the stand, which is fixed to the base and serves as a support for the movable contacts mounted on the keys. The keys do not fall out as they are held in place by a latch.
To gain access to the contact part of the switch, you need to remove the keys. To do this you should:
1) move the latch by pressing on the rectangular protrusion of its guide, which is located behind the base of the switch. If the switch is installed, then to displace the latch you need to press the end of the leash with a screwdriver;
2) without releasing the protrusion of the latch, move the key down and, pulling it towards you, remove it. In two and three-key switches, the keys are removed one by one.
Having removed the keys, we get access to the screws with which the wire strands are connected to the contacts. The common wire connected to the bottom screw supplies power to the bridge. The wires attached to the upper screws are connected to the fixed contacts (Fig. 104).

After connecting the wires, you need to install the keys:
1) the key is placed on the base so that the ends of the fork fit into the grooves of the stand. In this position the key should hang on the base;
2) by pressing the protrusion of the latch (or the end of its leash) and pressing the key to the base, move it down until it stops. After releasing the key, release the latch.
When removing and installing the keys, you do not need to apply much effort, and the wires should not touch the keys.
Such a switch - for three electrical circuits - is convenient, for example, in the hallway, so that you can easily turn on the light in the corridor, in the bathroom and toilet.
Two-button switches conveniently control the chandelier. One key turns on the first group of lamps, the second key turns on the other; both keys at once - all lamps (Fig. 105).

Ceiling switches and baseboard sockets

Ceiling switches have a cord drive (you need to pull the cord to switch) and are installed openly on wall panels under the ceiling. Wires laid in the floor slabs are inserted into a subceiling switch, which also serves as a junction box.
It is worth noting that when installing embedded and other hidden electrical wiring laid in floor panels, over-plinths can be used plug sockets. They are installed openly above the baseboard, attached to wall panel. If the panel is interior (inside one apartment), a second socket is mounted on its opposite side, which is connected to the first by a loop from the group line (Fig. 106).

Under-ceiling switches and above-plinth sockets are used if they want to reduce the labor intensity of work and costs when installing electrical wiring (no need to make grooves in the walls, waste wires going down from the ceiling and up from the floor).
Three fixed contact plates are attached to the switch body, which can be connected by a bridge (moving contact).
By pulling the cord, we act on the pusher, which rotates the bridge 90°, thereby closing or opening one or another group of contacts.
Thus, the switch has four positions: for example, 1 - disabled; 2 - the first group of lamps is on; 3 - both groups included; 4 - the second group of lamps is turned on.
Because the bridge turns only in one direction (clockwise), certain inconveniences arise. For example, in order to turn on the second group of lamps from the “off” position, you need to pull the cord three times, etc. (Fig. 107).

Switches combined with dimmers

Dimmers (dimmers) are non-contact devices designed to regulate lighting intensity, from a few percent to full. Losses in dimmers are minimal, no more than 1.5% of the power of the connected lamp.
From the oscillograms of the mains voltage and the voltage supplied to the lamp, which is turned on through the dimmer, it is clear that the more the sine wave is “cut off,” the lower the brightness of the lighting.
Switches combined with dimmers can be manufactured in different options execution: for example, turning on and off is done by pressing a button, and the lighting is adjusted by rotating the button around the axis, or turn on the light by pressing the button and, holding it pressed, adjust! lighting level.
There are touch switches, both with and without dimmers. The body of the switch contains an electronic circuit that is activated (turns the light on or off) when you touch metal plate. The brightness of the light is adjusted by rotating the holder (Fig. 108).

Electronic circuit The touch switch can be assembled into the base of a table lamp, and to turn it on or off, just touch metal part grounds.

How to choose a light switch

To choose required switch light, you need to have an idea about the structure of this device, its technical characteristics and the types of switches on the market.

Device

A light switch is a special device for closing/opening contacts that act on (switch) an electrical circuit that includes one or more electrical appliances.

The design of all types of switches requires the presence of a switching element that opens and closes the circuit in different ways. The design of light switches depends on the purpose, the amount of current they switch, as well as the number of electrical circuits being closed.

Specifications

Basic specifications switches is the rated current and Rated voltage. Their values are indicated on the products. They are necessary to calculate the permissible power at which lighting can be operated using a switch. If the switch connects more power than permissible, then the conductivity of the working contacts of the device will gradually deteriorate, the mechanism will heat up and very soon fail.

In this case, the electronic device will simply burn out. Household switches are usually rated for a load of 2.5 kW (at 10 A and 250 V). If it is necessary to place the switch in rooms with high humidity, then you should pay attention to its degree of protection, indicated by the IP code and two numbers.

For an apartment this is usually IP20, for a bathroom - IP44, for outdoor installation - IP55, IP65.

Mechanical and electronic switches

Depending on how the opening and closing of the electrical circuit occurs, a distinction is made between electronic and mechanical switches.

IN mechanical switches (keyboard, push-button, rotary, lever, cord, slide, etc.) the switching element is triggered by the action of a hand. IN electronic- from a radio signal (remotely controlled devices), infrared radiation or when a person approaches (touch switches and with a motion sensor).

In electronic switches, circuit switching occurs due to the presence of a semiconductor device in them. They are more durable, reliable and safe compared to mechanical ones, but they are also more expensive.

Switches with and without screw terminals

Based on the method of fastening contacts (wires), switches with and without screw terminals are distinguished.

In the first case, the contact is clamped using a screw between special plates. In the clampless version, it is held in place by a spring terminal or screwless clamp. Switches with screw clamp they are more expensive because they are considered to be of higher quality: the screw holds the contacts stronger and is more convenient to use.

Surface-mounted and wall-mounted switches

For open wiring, overhead switches are used, and for hidden wiring, switches built into the wall are used.

The latter are placed in a special mounting box, which is fixed in a recess made in the wall.

Switches and switches

Now, in addition to conventional light switches, which are adapted for the simplest on/off functions, so-called switches (changeover or walk-through switches) are manufactured. Externally, they differ from their predecessors only in the large number of contacts - they have 3, while regular ones have 2.

Review of modern light switches - in simple words about the complex

Therefore, the switches are capable of operating in 2 circuits at once (when one opens, the other closes (the device seems to switch contacts)).

Single-key and multi-key

A single-key switch is used to open/close the 1st circuit (turn on/off the 1st lamp), a two-key switch is used for multi-lamp chandeliers.

Sometimes two-key switches are used for separate bathrooms (one key for each). Three-key ones are needed for groups of lamps installed in large rooms.

With and without backlight

Illuminated switches have tiny LEDs built into them.

They make it easy to find the switch in the dark, and also serve as a kind of indicator that reminds you that the light is not turned off. The “eyes” on the keys, the frames, and the keys themselves can light up. The backlight can be colored.

Design, brands, cost, quality

Decorative panels of switches can be very different: made of plastic (including impact-resistant - duroplast), metal, wood, stone, porcelain.

They also differ in prices. Elite switches are considered to be devices from Spanish (for example, Fede), English (MK Electric), Italian (BTicino) and German (Berker) brands. Optimal price-quality ratio - products from Legrand, ABB, Siemens. Of the cheap options, Wessen and Tern devices are of sufficient quality.

When purchasing a switch, if possible, pay attention to the quality of its workmanship, some of the evidence of which is the silver-plated contact group, the smoothness of the surface and the clarity of the lines.

For the second lesson we will need:
1. Absolutely any single-key switch. The picture below shows one of its varieties.

On the left side of the figure is a single-key open wiring switch, presented in assembled form, on the right - disassembled.

What types of switches are there?

Most often, in order to disassemble the switch, you first need to remove its key by carefully prying it out from the side with a screwdriver or the tip of a knife blade. There are two screws under the key that need to be removed.

Now it becomes possible to separate the housing-cover from the switch mechanism, after which access to the electrical terminals opens. Anyone single-key switch, there should be two of them.

Old type switches are easier to disassemble - their keys are significantly smaller, and the screw holding the housing-cover and mechanism together is located outside.

A less convenient option for disassembly is when various latches are used instead of screws to secure the case-cover and mechanism.

In this case, disassembly requires special care - if you are careless, the latches can be very easily damaged.

2.Device assembled in the 1st lesson.

Approximately in the middle of the cable, in a section of about 20 cm.

layer needs to be removed external insulation.
This must be done very carefully - the internal insulation must not be damaged.

Next, cut one of the wires. We prepare the resulting 2 ends for connection - remove the insulation from the edges to the required length. As in the case of a socket, the bare ends either bend into a ring or remain straight, depending on the type of connection used in our switch.

In the picture below, they are bent into a ring.

If now, very carefully (without touching the bare wires under any circumstances) you plug the plug into the socket, the light will not light up. You can make it burn again by connecting back the 2 ends of the broken wire.

We disconnect them - the light goes out again. All connections involving touching the bare ends of the wires must be made by unplugging the plug from the socket.

After this, we connect the switch.

And close the lid - the body.

We plug the plug into the socket and press the switch several times in both directions.

The light comes on again, then goes out again. The conclusion suggests itself - the switch, at its core, is a controlled break in the electrical circuit.

A real picture of connecting a switch in a room may look like this

A 2-wire (minimum) power cable is inserted into the distribution box (1), one of the ends of which (null wire), goes directly to the el.

light bulb (chandelier, sconce, light cord). Second end of the power cable (phase wire) is connected to the switch input through a two-wire cable going down. (one wire is used) El. The current passes through the switch and follows to the light bulb, through the connection in the distribution box, along the second wire of the same cable.

What is the difference between phase And zero wires?

From the point of view of practical electrical safety, it consists in the fact that touching a single bare zero the wire is not dangerous for humans, but phase, vice versa. The result of touching, to the naked phase wire, can be very disastrous (even lethal).

Touching two live, bare conductors at the same time is even more dangerous. When the electrical circuit is installed correctly, the switch turns off exactly phase wire Nick,- are created safe conditions for working with a lamp (replacing electric

light bulbs, for example). Distinguish phase wire from zero, can be done using a tester screwdriver. When touched phase(bare) wire, the indicator will light up and zero- No.

Currently, during electrical installation in household premises, a three-wire electrical supply system is used. nutrition. In addition to the feeders (workers) phase And zero conductor, a third is added, - conductor protective zeroing.

All metal housings of household electricity. equipment ( washing machines, email ovens, etc.) are subject to protective zeroing . Read more about this in the “Replacing Wiring” section.

Well, as for the product assembled during this lesson, it will be useful for the next lesson.

Go to lesson 3

The use of any materials from this page is permitted provided there is a link to the “Electrical is Easy” website.

Operating principle and design of the switch

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The operating principle of the switch is based on extinguishing the electric arc with a vacuum arc extinguishing chamber (VAC).

Moreover, current passes through the vacuum chamber only in a short period of time when performing on and off operations. In the on position, the rated current and short-circuit currents pass through the main contacts of the switch, bypassing the KDV. In the off position, the main contacts open with the formation of a visible gap; the mains voltage is not applied directly to the KDV.

Since switching processes occur inside vacuum chambers, the switch does not generate emissions of arc combustion products both when disconnecting and when switching on, which eliminates the occurrence of an open arc and erosion of contacts.

The switch has versions with built-in grounding blades, which can be located both above and below.

The grounding blades can be controlled either left- or right-handed using drives of the PRS-10 type, and in a modular version - type PPRZ-10.

The switches are available in versions with phase-to-phase distances of 200 and 165 mm.

In addition, switches of modular design VNVR(M)-10/630-20 are also available with phase-to-phase distances of 130 and 100 mm, which allows their use in cabinets with a width of 600 mm or less.

11 High voltage circuit breakers (HV)

A switch is the main switching device designed to turn on and off the current in networks, under normal, emergency modes (for example, during a short circuit), overloads and abnormal modes.

Depending on the method of extinguishing the arc that occurs when switching the switch due to transient processes HV switches are divided into oil, air, vacuum, SF6, autogas and electromagnetic.

Oil switches are used in electrical networks and there are tank and core (low oil) ones.

The contact groups are immersed in oil.

Advantages: simplicity of design, presence of built-in current transformers, high breaking capacity.

Disadvantages: the need for periodic oil monitoring, fire and explosion hazard, impossibility of using autorecloser

Vacuum circuit breakers are the most promising. Arc extinction occurs in a vacuum.

The arc is extinguished at the first transition through “zero”. In this case, the possibility of overvoltage arises due to the fact that the load is usually inductive in nature, and the current cannot be interrupted instantly. Therefore, it is necessary to connect the arrester to the vacuum circuit breakers on the load side.

Advantages: high breaking capacity, high speed, small size, fire and explosion safety.

Disadvantages: complexity of manufacturing, lack of ability to control the vacuum depth.

SF6 switches - arc extinguishing occurs in an electronegative gas (SF6 gas, sulfur hexafluoride), which has high electrical strength.

Therefore, gas switches have good switching capacity and speed. Disadvantages - high cost; at low temperatures, SF6 gas loses its properties.

It is used primarily in networks with voltages of 110 kV and higher.

Electromagnetic switches. Arc extinguishing occurs by controlling the arc using an electromagnetic field. In this case, the arc is drawn into the arc-extinguishing chamber, where it breaks, stretches, and goes out when the current passes “zero.” used in 6-10 kV networks, and are capable of disconnecting high currents– up to 3600 A in nominal mode and up to 40 kA in emergency mode. Disadvantages - low voltage class, restrictions on outdoor installation, a complex arc-extinguishing chamber device.

Air circuit breaker - the arc is extinguished using “blowing” - in other words, the arc is blown off with air using a pneumatic system.

Used in networks of 35 kV and above. Has limited use. Requires a pneumatic system and produces a loud bang when switched off.

Autogas switch - the arc is extinguished as a result of the occurrence of gas, which is released as a result of the combustion of special inserts. (organic glass). Used in 6-10 kV networks.

Load switches (LCBs) are the simplest autogas switching devices.

The switch operates at a voltage of U = 6-10 kV and rated currents of 200-400, 630 A. It is a three-phase switching device designed to disconnect load currents and create a visible break in the line. There are HVs mounted on a common frame with fuses (designation VNP), and there are also versions with grounding blades (VNPz). The main difference between load switches and high-voltage switches is that HVs do not interrupt short-circuit currents.

VNP switches are manually operated.

General provisions for choosing electrical equipment.

The selection of electrical equipment is carried out in accordance with the PUE, PTEEP.
Electrical devices are selected according to the conditions of normal mode, and then checked for short circuit mode.

According to the data obtained from the calculations from catalogs and reference books, the required device is selected and tested for the most severe conditions.
At the same time, Unom ≥Ucalc, Inom ≥Iwork.max, Ioff≥I(3)k, and Idynamic resistance≥ishock thermal resistance Vk≤Ipr·τ

Relay protection

Purpose of the relay protection: 1) tracking and signaling – tracking and transmission of information about emergency and abnormal conditions.

2) protective function - timely shutdown of a section or element of the electrical power system to protect them from emergency and abnormal conditions

3) automation function - automatic influence on system elements in the following areas - control of equipment of stations and networks, in all operating modes.

These include devices for automatic start and stop of station units and generator switches for parallel operation of the power supply system (AGP - automatic field suppression, APV, AVR, AChR - automatic frequency unloading, voltage unloading, APAH - automatic termination of asynchronous operation of generators, necessary to eliminate rolling in the system).

Rotary light switch

Regulation of certain parameters, system modes, which include a device for maintaining voltage and frequency

Requirements for relay protection: Selectivity, Sensitivity, Reliability.

Selectivity is a property of relay protection that characterizes the ability to detect a damaged element of the electrical power system and turn off this element only by the switches closest to it.

This allows you to localize the damaged area and not interrupt normal work other parts of the network.

Current protection

Current protection is a type of relay protection that responds to an excess of current in the protected section of the network in relation to the operation current, or setting. Depending on how selectivity of action is ensured with subsequent (from the power source) protection, they distinguish maximum current protection (overcurrent protection) And current cut-off (TO).

In radial (open) networks on overhead lines of voltage class 6-10 kV and above, the most common option for organizing protection against three-phase and phase-to-phase short circuits is the use of two-stage protection, including overcurrent protection and maintenance

Maximum current protection(MTZ)— selectivity of action is ensured due to a delay in response time. Choice MTZ operation current is carried out in such a way that its value exceeds the maximum operating current at the place where the protection is installed by an amount that depends on the reliability and return coefficients of the relay, as well as on the self-start coefficient (usually no less than 1.2 - 2.0 times).

This eliminates the possibility of false protection action during normal network operation. When a short-circuit current flows, the relay operates, as noted earlier, with a certain delay.

Operation time setting the previous (from the power source) protection must be greater than the setting of the subsequent one by the value of the so-called selectivity stage Δt (about 0.2 - 1.0 s - depending on the type of relay on the basis of which the protection is implemented).

Current cut-off (TO)— selectivity of action is ensured by detuning from the maximum short-circuit current at the end of the protected zone.

TO is a fast-acting protection that operates without a time delay and turns off the most severe short circuits near the power buses. Magnitude cut-off current should be approximately 1.1 - 1.2 times higher than the rated current of a three-phase short circuit at the end of the service coverage area (i.e. at the location where subsequent protection is installed); the specified multiplicity is determined by the reliability coefficient of the relays used.

TO sensitivity coefficient, based on the PUE, can be calculated as the ratio of the three-phase short-circuit current at the place where the protection is installed to the actual cut-off current, and must be at least 1.2.

In other words, the current cut-off area should cover about 20% of the line length. The disadvantage of current cut-off is the limited coverage area, so it is used only in conjunction with overcurrent protection as a second stage; At the same time, TO has absolute selectivity, because the magnitude of the short-circuit current outside the protected zone is always less than the cut-off current.

Differential protection- one of the types of relay protection, characterized by absolute selectivity and fast-acting (without artificial time delay).

Used to protect transformers, autotransformers, generators, generating units, engines, power lines and busbars. Distinguish longitudinal And transverse differential protection.

Switches in residential buildings Mainly used to turn lights and other household electrical equipment on and off. The use of these devices should be safe, convenient and durable. Therefore, for a certain task, there is a type of switch that the best way solves it.

Push-button

In household electrical equipment, special switches are used, which must be small, convenient and correspond to the characteristics of a particular device. Widely used for table lamps and other electrical devices with power consumption up to 300 W from a 220 V network, push-button design with locking. It is very small in size and easy to use. There are structures placed on the body of the device and on the wire that connects it to the network.

Most often, the button is retracted only when pressed, which is done both when turning the device on and off. This design is the least reliable, because over time, but quite soon, the button begins to be difficult to either press or press. The button is pressed by a spring. The force that the spring develops is selected based on the comfortable pressing. And this force may not be enough when disconnecting a load that is too large for the contacts of such a switch. After all, when turned off, a spark is formed with the effect of spot microwelding.

Therefore, you should not use lamps in lamps that are too powerful for the latching push-button switches installed in them.

Reversible

The changeover switch design is another compact solution for electrical equipment.

The dimensions of such switches are larger than those of push-button switches with locking. Switching on is ensured by the elasticity of the spring contact. And switching off occurs from the force of pressing. This feature allows you to expand the scope of application to powerful electrical equipment and obtain a long service life.

Several types of switches are used in rooms to control lighting. There are two designs according to the mounting method:

with recess into the wall;
with mounting on the wall surface.

Surface fastening is most justified when external electrical wiring. But for connoisseurs of retro style they are also good, since it all began with external switches. The first designs were rotary. The rotating design was optimal for the technology of those years, and plus it is the most reliable.

However, a key switch recessed into the wall looks more aesthetically pleasing and is much more convenient to use. Therefore, this design has become predominant in our time. It is based on a type of rocker switch, but equipped with a large and convenient key for touching and pressing. There may be several keys to turn on the lamps separately.

For convenient use in the dark, the key is backlit. The keyboard design is used for general lighting living rooms and other premises without special requirements for electrical fittings.

The keyboard design, although it looks good, requires careful handling. Therefore, indoors common use apply changeover switches with durable structural elements.

For local lighting

In residential premises, for comfortable reading and hanging out, floor lamps and sconces are used, placed near sofas, armchairs and resting places. They create local lighting. The most convenient design for controlling local lighting is a switch with a hanging chain or cord.

The local lighting lamp is alternately turned on and off by pulling the chain or cord.

Other types of switches for local lighting can be structures combined with a power cord that connects the lamp to the mains. Typically these are push-button and slider designs.

Electronic

In addition to the considered switch designs, which are completely mechanical, in last years new electronic ones have appeared. They use semiconductor switches with control circuits. Semiconductor switches perform the function of contacts. But to control these keys, a light touch on the touch button is enough. In addition, there may be a remote control remote control like the image below

The sensors in the key control circuit may be different. For example, a photocell that reacts to the weakening of daylight can trigger automatic switching on or off in a timely manner. The motion sensor initiates switching on when approaching and switching off when moving away from a person or, for example, a car near a garage.

The key can work not only as a contact, but also as a power regulator in the load. This allows you to adjust the brightness glowing lamp. These controls are called "dimmers". But the key cannot, like a mechanical switch, break the electrical circuit. Since it is necessary to create a physical break in the chain, they are combined into one.

All switches must be connected to the wiring and load so that a gap is created between the load and the phase. This is easy to check indicator screwdriver. The conditions that exist in the room should determine whether the switch is designed to be waterproof or spark-proof.

A correctly selected and installed switch is the key to safe and convenient operation of electrical equipment.

Today, not a single room is complete without light switches. These switching devices allow you to easily and quickly turn off and turn on any lighting fixtures. In addition, today there are switches that allow you to smoothly control the degree of illumination. To replace an old device with a new one, you need to know the structure of the switch, understand the range of switches and the criteria for choosing a device, and be able to correctly connect the device to the electrical wiring.

Light switch structure

Light switches are switching devices that are used to open/close contacts in an electrical circuit connected to one or more lighting devices. Such devices are not intended to interrupt short-circuit currents; they are used in household networks with voltage up to 1 kV.

Regardless of the type, structure household switch assumes the presence of a switching element in it that affects the electrical circuit.

The basis of switching elements is an electromagnet. The input signal in such devices is voltage or electric current. At the same time, switching elements can be controlled manually or automatically. Accordingly, household switches are divided into varieties according to the principle of actuating the switching element. The design of switching devices for lighting control depends on the magnitude of the current and voltage that they switch, and the number of groups of electrical lighting devices.

Mechanical light switches: types

In order to choose a contact lighting switch, you need to know what types of switching devices are offered modern market. So, all room electrical switches are divided into mechanical and electronic.

Today, mechanically controlled switches are especially popular.

They are distinguished by their availability and wide range. The switching element in such models is activated by mechanical action (pressing buttons, moving toggle switches to a different position, turning handles).

According to the type of control element, mechanical switches are divided into:

Rotary (round switch with rotary handle);
Push-button (may have a round or polygonal button);
Keyboards (a regular flat switch with one or more keys, depending on the number of lighting fixtures controlled by it);
Toggle switches (lever switches).

A special category is made up of rope switches, which are often found in construction wall lamps. In addition, such switches are suitable for ceiling mounting, wall installation at a height greater than recommended.

Household electrical switches: types

They are considered more durable, reliable and safe, in comparison with mechanical ones. electronic switches Sveta. Circuit switching in such models is performed using semiconductor devices, which reduces the likelihood of short circuits. Such devices act on the circuit after receiving a radio signal and triggering a motion sensor.

Depending on the principle of operation, modern electronic switches are divided into:

Electronic with motion sensor;
Sensory;
Remote.

Separately, there is a pass-through electrical switch, which is used to control the degree of illumination - a dimmer. In appearance, a dimmer most often resembles a rotary switch. Dimmers are distinguished depending on the type of lamps being controlled.

How to choose a light switch

When choosing a switching device, it is necessary to take into account not only the type of switch, but also the type of wiring. The method of mounting the switch depends on this. Yes, when open wiring use external switching devices.

An external light switch does not have a recessed mechanism and is often called a surface mounted switch.

For hidden wiring choose internal (hidden) switching devices, the mechanism of which is recessed into the wall. In addition, when choosing a device, you should pay attention to its technical characteristics and the material of its manufacture.

So, when choosing a household light switch, you should consider:

The rated current that the device can withstand. So, for apartments and residential buildings, devices designed for current with a voltage in the range from 110 to 250 Volts are suitable.
The voltage that the device can withstand. To calculate this value, you need to know how many lighting devices the switch will be designed for and their power.
Device manufacturing material. Switches with a ceramic base are considered the most durable and reliable. But for small rooms in an apartment, you can also choose ordinary plastic ones.
Properties of the device body. Thus, switches can have a shockproof housing and protection from moisture. Information about the degree of protection of the switch can be found on its body (the marking has two numbers and two letters). For bathrooms, you should choose devices with IP44 code.
Switch size. Standard size devices with a single frame - 8.5x8.5 cm. A narrower single-key switch can be 5-6 cm wide. Little ones push button switches Lights are usually used directly on lighting fixtures.
Brand and cost of the switch. It is best to take original switches: although they are more expensive than fakes, they will last longer. Switching devices from MK Electric, BTicino, Berker are considered elite. The optimal price-quality switches are made by Legrand and Siemens. More affordable, but no less high-quality devices can be found from Tern and Wessen.

In addition, it would be a good idea to pay attention to the presence of additional functionality of the switch. For example, models with backlighting (LED or fluorescent) will be convenient.

What are the differences between industrial light switches?

Industrial circuit breakers are designed primarily to protect the network from overcurrent and short circuits. They are reusable automatic switching devices equipped with a direct-acting thermal or electromagnetic relay - a circuit release. Such switches have big sizes, are manufactured with a manual or motor drive, and are three- and/or four-pole.

Each model of industrial circuit breaker has its own maximum short circuit current, which does not damage the device and electrical equipment.

Current exceeding this value may cause contact welding or fire. Therefore, industrial switches are selected depending on rated current on the object. Such switches are produced with ratings from 10 to 4000 A.

According to their purpose and operating principle, industrial switches are divided into:

Automatic switches for the protection of single- and three-phase low-power electric motors;
Switch-disconnectors;
Limit switches (limit switches).

Such switches are used on industrial enterprises, in buildings and structures for civil and residential purposes, switchgear of electrical substations.

Electrical switch: connection diagram

The simplest is to connect a single-key switch to turn on and off lighting fixtures. In order to make the connection correctly, the circuit must include a switch, junction box, power source, and connecting wires.

At the same time, it should be taken into account that any type of switch (including pass-through) is connected to the electrical wiring to break the working phase wire.

Only such a connection can provide safe operation connected through an electrical equipment switch. Otherwise, if the connection is made intermittently neutral wire, the wiring will be live, which is unsafe for life and health. You can determine the phase wire in an existing electrical wiring using indicator screwdriver: If the screwdriver indicator lights up, the wire is live.

The diagram for connecting lighting devices through a switch looks like this:

From the electrical panel, the working wires (zero, phase and ground) are led to the distribution box;
Phase the wire goes to the switch, to the break, and then to the lighting fixtures;
Zero and ground go to the lighting fixtures, bypassing the switch.

Two- and three-key switches are connected according to the same principle with the addition of additional phase wires, going from the key to a separate lamp. Before carrying out connection work, you must make sure that there is no voltage at the facility. This can be done using the same indicator screwdriver.

How to choose a light switch (video)

A light switch is an important switching device that is used to open/close contacts in an electrical circuit. All switches are divided into types depending on the principle of control of the switching element. Using the selection criteria and recommendations above, you can choose the most suitable device for your purposes!