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Types of double switches. Household switch. Single-key and multi-key

The lighting equipment market is constantly evolving, and the range of switches is being updated with innovative developments that provide maximum comfort. However, traditional devices do not lose popularity. Agree, among such variety it is not easy to decide on the purchase of a suitable light switch.

To make choosing easier, we have prepared detailed review existing switching devices, classified the types and types of light switches according to the main technical parameters, and also described the features of their installation and use.

In addition, the article lists best manufacturers lighting devices. This information will help you choose a high-quality and reliable option for specific operating conditions.

A switch is a switching device that is responsible for closing/opening the electrical circuit that powers the lighting fixture. It is always installed in the area where the phase wire breaks.

You cannot trust illiterate “electricians” who claim that zero and phase wire. This will cause a short circuit and wiring problems.

Household switch models are designed to work with wiring using regulatory burden. They cannot be connected to a network with other parameters. Each of the switches can only operate with a certain operating voltage and current. These parameters are always specified in technical documentation and on the device body.

The main task of the device is to provide power to the electrical device and stop it when there is no need to use the lamp. Switches are available in a wide variety of designs. They differ significantly from each other in a number of ways. Let's take a closer look at these differences.

A standard switch is connected to the area where the phase wire is broken. The purpose of the device is to close or open an electrical circuit, thereby turning on the lighting fixture

Switching methods used in switches

When installing switches, only two methods of connecting wires are used, which have certain features.

Screw clamp mechanism

To switch wires, this type of switch has special clamps that are secured with ordinary screws. This connection method is more difficult to install, but the result is a high-quality contact. Over time, this connection may loosen a little and then you will have to slightly tighten the screw.

Pass-through or reversible models

They allow you to control lighting from several places remote from each other at once. One or more lighting fixtures can be connected to such devices.

Popular manufacturers: who to prefer

The quality of switches, like any other product, largely depends on the manufacturer. Companies that have earned a good reputation strictly monitor the quality of their products, guaranteeing customers long-term, trouble-free service for their products.

Therefore, when choosing a switch for your home, it is important to pay attention to this point and, if possible, choose products from famous manufacturer. Let's talk about the best of them.

Legrand company from France

The French brand entered the market in the mid-19th century with table porcelain. After the advent of electricity, porcelain became in demand as an insulator, and the company began producing electrical products.

Management initially relied on use in production latest technologies, which yielded good results - the company is one of the five best European electrical manufacturers.

Products Legrand known in more than 150 countries around the world, it is sold under various brands, including Contactor, BTicino, Sarlam, Legrand and others. The company's products are distinguished by the highest quality, safety and reliability.

The product range is very wide, it includes the most different types wall switches. Among them you can find traditional models, as well as unusual combination devices.

They are a three-key or standard switch installed in a common housing with a socket. The company pays Special attention quality of components.

In addition, the housings of all devices, regardless of their cost, are made only of self-extinguishing plastic. This significantly increases the operating safety of the devices. Legrand produces its own devices different designs that fit into any interior.

Swedish company ABB

It appeared at the end of the last century as a result of the merger of two large Swedish concerns. Today it is one of the leading manufacturers of electrical installation products. Their distinguishing feature– highest safety and quality.

The brand offers comfortable modular solutions, allowing you to collect the necessary variations from the proposed elements. For the production of cases, only impact-resistant, UV-resistant materials are used.

ABB brand products are distinguished not only by the highest quality, but also stylish design. True, the cost of such electrical installation devices is quite high.

Among them are natural ones, such as steel, wood or bronze. The structural simplicity of the products allows for simple and quick installation.

Brand assortment ABB includes several product lines, each of which has a special, easily recognizable design. Eg, Reflex made in traditional strict geometric shapes, and here Impuls has soft rounded lines.

Collections of electrical installation products are diverse. Moreover, even in basic collections, the manufacturer offers not only standard solutions.

For example, all have frames with a fluorescent coating, which illuminate the body of the device in the dark. ABB products are highly expensive, which some consider to be a significant disadvantage.

French brand Schneider Electric

Founded in the 19th century as a weapons production company, it has long mastered the electricity markets and become a leader in the production of electrical installation products.

In the product range Schneider switches with light indication, walk-through switches, with remote control, with sensors and other complex variations. Moreover, they are all of the highest quality.

The Schneider company has launched the production of combined electrical installation devices assembled on a common basis

The signature feature of Schneider products is the presence of spring contacts made of bronze. This allows you to avoid using an additional clamp without losing the quality of the contact created. Thanks to this, installation of products from the French brand is extremely simple and fast.

The design of electrical installation devices is widely varied. Here you can find interesting models in a different range: from laconic classics to catchy avant-garde.

All brand collections include removable horizontal and vertical frames of various colors. The company's products are represented by several model lines. Very popular Unica, offering modular devices that allow you to create a variety of combinations of elements based on a unified seat.

We compare electrical installation devices from different manufacturers:

What does the housing protection degree marking mean:

Modern switches are complex devices that make a person’s life as comfortable as possible. At the same time, they also help save energy; this applies to high-tech models equipped with light and motion sensors.

Manufacturers produce products of different designs, which allows them to easily fit into interiors of any style. It’s easy to choose from a range of models suitable option, you just need to determine which switch is needed for existing conditions operation.

Do you have anything to add or have questions about choosing a light switch? You can leave comments on the publication and participate in discussions. The contact form is located in the lower block.

All switches and switches are designed for one thing - to turn on or off (close or open contacts) lighting at the right time. They are designed for both exposed and concealed 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 efficient. 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.
Switches that are installed in the base 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.
It is more convenient to turn a floor lamp and some household electrical appliances 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 (an area with a thinner layer of plastic than at the base itself) in the mounting 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 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 circuit breakers are rated current and rated voltage. Their values ​​are indicated on the products. They are necessary to calculate the permissible power at which lighting devices can operate 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 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 electrical circuit opens and closes, electronic and mechanical switches are distinguished.

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-gang 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. Any single-key switch must have 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.

it is necessary to remove the outer insulation layer.
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 are either bent 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 conductor,- 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, for electrical installations in domestic premises, a three-wire power supply system is used. nutrition. In addition to the feeders (workers) phase And zero conductor, a third is added, - conductor protective zeroing.

All metal cases household el. 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 rated current and currents short circuit 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 modular design VNVR(M)-10/630-20 are also available with interphase 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, with 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, complex design of the arc-extinguishing chamber.

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 circuit breakers is that HVs do not interrupt short-circuit currents.

VNP switches are manually operated.

General selection provisions 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 the normal operation of 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.

Today, the range of electrical products can provide the creation of any design solution, make control of light in the room comfortable and pleasant. 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 an 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 household use you can choose a switch 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. In appearance, such switches are no different from ordinary ones, but inside there are some design differences. 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 of 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 there will be no short circuit in it, since there are no mechanical contacts in the device. 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 V own homes overhead switches are suitable. For hidden electrical wiring, there are hidden types of 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 an ideal option to choose 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 damage appearance.
  • The body must have the quality mark of Rostest or the manufacturer.
  • There should be no sharp sound coming from the body bad smell. 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.

A switch is an electrical device designed to connect and disconnect an electrical circuit. Most often, switches control lighting fixtures, less often they are used to turn on and off exhaust fans, air conditioners, etc.

According to the type of installation, switches are divided into concealed switches and switches external installation. The former are used when installing hidden electrical wiring, the latter - when laying wiring in an open way.

Types of switches

The switch is the device that people most like to improve and tweak additional options technical designers. Depending on the methods of switching, adjustment, purpose and protective properties of the housing, switches can be divided into several types.

1. Keyboards

The most common type of switches. The electrical circuit is closed and opened when the key is switched from one position to another. One-, two- and three-key versions are available.

Key switches are inexpensive, convenient to use and easy to repair. On the other hand, they have a rather low operating life, the lighting intensity cannot be adjusted, and there is no energy saving mode.

2. Push-button

Principle of operation push-button switch similar to a keyboard: you press a button - it locks and closes the contact. Pressing it again opens the contact. Often released with LED backlight. Such switches should not be confused with ordinary electrical buttons, for example, on a bell: such buttons make a contact only if they are held by hand.

Push-button switches will easily fit into the interior of any room, despite their slightly non-standard appearance. They cost a little more than their keyboard counterparts. But they will serve you faithfully for a long time.

3. Dimmers (switches with regulator)

They are a kind of rheostat, which is familiar to most of us from school physics lessons. A dimmer works on the same principle. A rheostat changes the resistance of an electrical circuit, and therefore the current strength in it. Higher resistance means lower current. The lower the current, the dimmer the light bulb included in the electrical circuit burns. With the help of such switches, you can adjust the lighting intensity by turning the control wheel.

The advantage of dimmers is energy savings (some devices even turn off on their own when no one is in the room) and ease of use. But there is also a minus: due to the high cost, not everyone can afford such switches. Note: dimmers work great with incandescent lamps, but with fashionable ones Lately LED lights and lamps may conflict and function incorrectly.

4. Rotary

About 50 - 60 years ago, rotary switches were still actively used in the construction of houses, but recently they have been used only in “antique” design projects or in creating interiors in country, loft, and Provence styles. As a rule, they are produced only for outdoor installation and are used in conjunction with open wiring. Switched by turning the lever 90°.

5. Rope

The operating principle of this switch is similar to a push-button switch: by pulling the string until it clicks, you close the contacts. Pull a second time and open. This type of switch is mainly used in wall sconces and sometimes to turn on exhaust fans.

Rope switches are used not only in decorative purposes, they have a number practical advantages. For example, a dangling cord is easy to find by touch in the dark, and such switches are also suitable for families with small children; the child can easily reach it and be able to turn the light on and off independently.

6. Touch

A modern type of switch with a long service life due to the absence of mechanical parts. Triggered by touch. Many models of touch switches are equipped additional functions, such as smooth dimming or auto-off. They like to use such switches in “smart homes”.

7. Acoustic


Such switches are also called clap or sound switches. Switching on occurs from the supply sound signal a certain volume, such as clapping your hands. Switches of this type with a timer are installed not only in apartments, but also in staircase landings. Some models provide a time setting after which the switch disconnects the circuit. Often acoustic switches are hidden in distribution boxes and are duplicated by regular keyboards.

The main advantage of this model is obvious: with it you don’t have to feel for the switch in the dark or walk across the entire apartment in dirty shoes because you forgot to turn off the lights. However, such devices do not always respond the first time and can operate spontaneously, which sometimes irritates owners.

8. Remote

These are switches that are activated by a signal from the remote control. Meet and combined models: e.g. touch switch with remote control. Remote switches are not very common because they are quite expensive. In addition, remote controls tend to get lost.

But there are also advantages. Firstly, with remote switches you don’t have to damage the walls: you just need to arm yourself with screws or double-sided tape and secure the switches in in the right places. And no problems with fixed wiring. Secondly, you can turn light bulbs on and off from anywhere in your apartment or house and feel like the master of light.

9. Passing


Externally, a pass-through switch is no different from an ordinary one, but its internal filling has a slightly different layout. Pass-through switches allow you to control one electrical appliance (or a group of electrical appliances) from different points in space.

For example, you have two-storey house. You approach the stairs and turn on the lamp that illuminates it with the switch located below, on the first floor. You go up to the second floor. Light on the stairs is no longer needed. If there was a regular switch downstairs, you would either have to leave the light on the stairs on or go down to turn it off. This is exactly the problem that pass-through switches solve: you place them on top and bottom and control one lamp from different points.

Unfortunately, in order to fit such convenient pass-through switches into the lighting system of your home or apartment, you will have to spend a lot of money and effort (compared to classic options) due to the complex wiring diagram, the impressive amount of materials used and the high cost of the mechanisms themselves.

10. Sealed

A special type of switches is hermetic switches designed for installation in rooms with high humidity or dust: in baths, saunas, showers. Just like waterproof sockets, they are classified according to the degree of protection. Thus, a switch that is installed in a bathroom or shower must have a protection class of at least IP-44. Read more about protection classes in our.

11. Switch with built-in motion sensor


As the name implies, the switch, or more precisely, the sensor connected to it, reacts to movements: the light turns on when a person appears in the field of view of the sensor, and turns off when that person disappears from it. Most often, the operating principle of such sensors is based on tracking infrared radiation.

Switches with built-in motion sensors save energy. Using them, you can also adjust the intensity of lighting, turn on spotlights, sirens, CCTV cameras and control other useful equipment. Unfortunately, these super mechanisms come at a price to match.

Useful tips


  • For the bathroom and kitchen, use sealed switches with a moisture and dust protection class of at least IP – 44
  • Rope switches will fit harmoniously into the nursery: the baby can easily reach the cord and can quickly turn on the light in the dark if he suddenly has a bad dream at night
  • Dimmers are best suited for the living room, since to watch TV and read a book you need different quantities Sveta
  • For your convenience, stairwells in a private house should be equipped with either walk-through switches or switches with built-in motion sensors

Having become accustomed to using the benefits of civilization in everyday life, people stop noticing them, taking them for granted. This is exactly how we treat lighting fixtures, sockets and switches. Pressing the key, hardly anyone thinks that technology does not stand still and is changing. familiar devices their new generation has already arrived.

Modern building materials, making it possible to make each home special, have caused the emergence of new trends in the organization of home lighting, which could not but affect the devices connecting lamps to the electrical network. A new generation of switches has appeared - beautiful, convenient and functional.

Classification of switches

On this moment switches can be divided according to three criteria:

Device installation type. Depending on the type of wiring, which can be external or hidden, switches are also divided into external or hidden devices.

IN modern apartments Most often, the wiring goes inside the walls or under a layer of plaster, so the switch is installed in a special box, recessed into the wall and fixed with adjustable legs, leaving only the housing outside. These devices have an attractive appearance and come in many different designs.

In old houses with wooden walls and ceilings can still be found open wiring when electrical wires are attached directly to the surface of walls or ceilings using special rollers. This method is often used to organize power supply, bathhouses or modern houses, the interior of which is stylized “antique”.

The devices for these postings also differ. For external use, larger sockets and switches are used, which are installed directly on the wall using a socket box. Modern models They look good, but they stick out a lot above the surface. But it is easier to maintain and repair such switches than hidden devices.

Wire switching method. The wire inside the switch can be attached in two ways:

For aluminum wires Fastening the cores with screws is more common. For this purpose, a special clamping plate is used to securely fix the cores in the input hole. But over time, the screw fastening may become loose and will have to be tightened.

Screwless fastening is often used when using copper wires. Its design ensures reliable contact between the wire and conductive fittings.

Variety of control methods

According to the control method, switches are divided into the following types:

Such devices look original in the room. There are models with several buttons, decorative trim and light indication. The choice is quite large, so you can choose a device for any interior.

  • Rope - used for decorative purposes and in places where the lighting fixture is installed high.

Such a switch is easy to find in the dark; they are used in children's rooms so that the child can turn on the light independently.

  • Keyboards are the most popular type of switches. They are beautiful, comfortable, and come in many varieties and colors. Almost all lighting systems for office and residential premises are equipped with them.

The device may have one, two or three keys. This allows you to organize the control of separate groups of lighting devices. Widespread use is due to such advantages as:

- low price;

— easy replacement, repair and installation;

— ease of use.

Such a sensor activates the lighting when a person appears and turns it off when there is no movement in the room. Such devices are most often mounted on the ceiling so that they have a wide viewing angle. They are used to temporarily turn on lights in certain places. For example, on the stairs, where there is such a sensor in each flight, the light will turn on where the person is currently located.

The device is based on a microcircuit instead of sliding contacts. This eliminates the occurrence of short circuits and increases the service life of the lamps several times. There is very little wear on the device, which increases its service life.

  • Remote - are a set consisting of a flat control unit and a remote control. To install, you do not have to drill into the wall; the device is secured using self-tapping screws or even double-sided tape where it is convenient to use it.

The principle of operation of the device is as follows: when you press the switch button, a radio signal is sent to the relay, and it closes or opens the circuit in the phase that goes to lighting fixture. The range of action of such a switch can be 20 - 25 m. The power source is a battery, which lasts about 5 years.

The device operates via digital signals and does not create interference. The presence of a control panel makes using such a device even more convenient. Remote switches are often part of a smart home system.

  • Dimmers - allow you to adjust the light intensity and can have a fairly wide range of functions:

— light brightness control;

— automatic shutdown;

— imitation of presence;

— smooth switching on – switching off;

The external panel of the device can be equipped with keys, a rotating button, infrared sensor. Dimmers are divided into three large groups:

- for energy-saving fluorescent and LED lamps, equipped with electromagnetic ballast;

— for halogen lamps and incandescent lamps;

For halogen lamps connected via ferromagnetic or electronic transformers.

- reversible;

— checkpoint;

- duplicating.

Externally, these devices resemble a regular key switch, but have a different operating principle. Regular switch only opens the circuit, and the switch, opening one circuit, switches the contact to another. This allows you to control in several places at once.

What makes using switches difficult is that you have to create a complex electrical circuit. The cost of the switches themselves is higher than the cost of conventional ones. However, ease of use is constantly expanding the scope of their application.

Thus, modern switches, in addition to their use for their original purpose, allow solving a whole range of problems:

  • save energy;
  • control lighting;
  • complement the interior of the room due to the variety of models and colors.