Connecting a circuit breaker - how to do it yourself. Detailed instructions on how to connect a circuit breaker Rule of connecting a circuit breaker

Content:

Automatic switches, called in everyday life machines or switches, belong to the means of switching and are intended to supply electric current to any object. The main function of these devices is to automatically cut off the power supply in the event of an emergency and network failure. The machine protects the electrical circuit from short circuits, overloads and voltage drops in excess of the permissible value.

In the houses of the old buildings, in the power supply system, the zero wire was not only a worker, but also performed a protective function at the same time. In modern buildings, a clear separation is provided for the purpose of working and protective conductors. In this regard, the question often arises of how to connect a circuit breaker, since all European wiring products are equipped with terminals for connecting a ground wire. In addition, the fixing of the machines themselves in the control cabinet can be done by mounting on a DIN rail or on a special mounting panel.

Device and principle of operation

Before connecting the machine, you need to understand the features of its design and the principle of operation. The circuit breaker consists of a housing, a switching device, a pushbutton or handle-like control mechanism, an arc chute and screw terminals at the top and bottom.

For the manufacture of the housing and the control mechanism, a durable plastic is used that does not support combustion. The switching device consists of movable and fixed contacts. Each pole of the machine consists of a pair of these contacts and is equipped with its own arcing chamber.

The purpose of the arc chute is to extinguish the electric arc that occurs when the contacts are broken under load. The chamber itself is made in the form of a set of steel plates with a profile of a certain shape. They are isolated from each other and are located at the same distance relative to each other. It is to these plates that the arc is attracted, which here cools and fades away. The number of pairs of contacts in different models of machines ranges from 1 to 4. The devices have position indicators. Red indicates on and green indicates off. In this way, the current state of the circuit breaker can be determined very quickly.

All parts are hidden inside the case, only the top and bottom screw terminals, control handle and indicator are visible from the outside. There is a latch on the body that allows you to quickly install the machine on and just as easily dismantle it.

To disconnect the machine, there is a special mechanism called a release. Each type of release has its own design. For example, in conventional machines, the function of the disconnecting device is performed by a coil with a winding and a core. Copper insulated wire is used for winding. The coil is connected to the electrical circuit in series with the contacts, since it is along it that the load current moves. If this current exceeds the set permissible value, then under the influence of the magnetic field of the coil, the core moves and exerts a mechanical effect on the disconnecting device. As a result, the contacts of the circuit breaker open.

The design of the thermal release has its own characteristics. It includes a special bimetallic plate. For its manufacture, two types of metals are used, dissimilar in their composition and with different coefficients of linear expansion. The plate is connected in series with the load. During the operation of the machine, it is heated by the current passing through it. In case of overload, the plate bends towards the metal with the lowest expansion coefficient. The trigger comes into action, disabling the machine. The more the current exceeds the rated value, the faster the thermal release will trip.

Installation of circuit breakers

The connection of the circuit breakers in the control cabinet is carried out in a specific sequence. A cable is connected from above, connected to an external current source, and through the outlets located at the bottom, the wiring is routed to its objects, in accordance with the electrical diagram.

At the beginning of installation, an introductory machine is connected. If there are several lines in the circuit, isolated from each other, they are separated from the input circuit breaker. Its power must be no less than the total power of the machines connected to separate lines. For this purpose, two- or four-pole devices of group D are selected, which are resistant to the inclusion of a power tool and other powerful equipment.

The most widespread are those suitable for any power supply schemes for apartments and private houses. Modular circuit breakers are mounted on a DIN rail and connected by conductors with a current carrying capacity exceeding the operating current of the circuit breaker. A more convenient connection of several machines in one row can be done using a special connecting bus. A piece of the required length is cut from it and fixed in the terminals. This connection is possible due to the distance between the bus contacts corresponding to the standard width of the modular machines. The switch is installed on a phase, and the neutral conductor is supplied from the input device directly to the devices.

Single pole the switch is used when installing sockets and lighting systems.
Bipolar the machine is suitable for high power appliances such as an electric stove or a boiler. In case of overload, it is guaranteed to break the circuit. The wiring diagram for such switches is practically no different from single-pole models. For more efficient use, it is recommended to connect them to a separate line.
Three-pole the circuit breaker should be installed only in cases where it is planned to use electrical appliances operating at a voltage of 380 V. In order to exclude, the load is connected according to the "triangle" scheme. Such a connection does not require a neutral conductor, and the consumer is connected to its own switch.
Four-pole a circuit breaker is most often used as an input. The main condition for connection is the equal distribution of the load on all phases. When equipment is connected according to the "star" scheme or three separate single-phase wires, surplus current will go through the neutral conductor.

With an even distribution of all loads, the neutral wire begins to perform a protective function in the event of unforeseen power imbalances. To ensure a normal connection, use only quality materials. All connections must be securely fastened to the terminals. If several cables are connected at once, their contacts must be carefully cleaned and tinned.

The procedure for connecting can be seen on the example of a two-pole circuit breaker installed in a panel. First of all, the electricity is turned off in order to completely de-energize the network. The lack of electricity is checked using an indicator screwdriver or a multimeter. Then the machine must be installed on a DIN rail and latched with a latch. The lack of a mounting rail can create certain inconveniences. After that, the conductors of the incoming and outgoing wires are stripped at a distance of 8-10 mm.

Input wires are connected to two clamps located on top. In the lower clamps, similar outgoing conductors are fixed, distributed to sockets, switches and electrical appliances. All wires are properly clamped in the terminals with screws. The connection points must be checked manually. To do this, the conductors must be gently moved from side to side. In the case of a poor-quality connection, the core will stagger in the terminal and may even jump out of it. In this case, tighten the terminal screw.

At the end of the installation, voltage is applied to the network and the functionality of the circuit breaker is checked.

How to choose the right machine

Choosing the right circuit breaker is essential. Each device has its own characteristics, such as rated current, mains operating voltage, number of poles, maximum short-circuit current, time-current characteristic and other important values.

The response time of the device has a numerical designation indicating at what current the normal operation of the circuit breaker is maintained. In home electrical networks, machines with numbers 4500, 6000 and 10000 amperes are most often used. All technical characteristics are indicated by manufacturers directly on the device case. This also includes the connection diagram, as well as the symbol of the machine.

The main criteria for choosing a circuit breaker are the load power and the cross-section of the wires used. In addition, overload current and short-circuit breaking current are taken into account. As a rule, overloads in the network occur when devices and devices are simultaneously turned on with a total power, which causes excessive heating of conductors and contacts. Therefore, the tripping current of the machine installed in the circuit must be greater than or equal to the calculated one. Its value is defined as the sum of the capacities of all devices used, divided by 220.

The short-circuit breaking current also causes the circuit breaker to trip. It is selected by calculations for a specific circuit and depends on the loads used most often. In order to improve protection, they can be included in the electrical circuit.

Errors when installing the circuit breaker

When performing electrical work, sometimes serious mistakes are made, which can lead to negative consequences in the process of further operation.

The power cable is connected from the bottom. Although it is not prohibited by the PUE, such a scheme will be inconvenient, since the installation and placement of machines in the panel is designed specifically for the upper connection.
A common mistake is to over-tighten the contacts with the locking screws. This can lead not only to damage to the core, but also to deformation of the product body.
Sometimes the wrong connection of the conductors is made to each other. It is necessary to pay close attention to the marking, connect the phase and neutral wires located above, with the same wires located below.
In some cases, one two-pole circuit breaker is replaced by two single-pole ones. This categorically cannot be done, since they do not provide simultaneous phase and zero separation.
Often, during the fixation of the core in contact, the insulation gets into the seat. This leads to a weakening of the contact, as a result of which the core overheats and other negative consequences. Therefore, it is imperative to protect the wire in accordance with the technical requirements of a particular machine model. This operation should be carried out using a stripping tool.

The wrong choice of a circuit breaker, which subsequently is not able to withstand the planned loads, can play a negative role. Therefore, it is recommended to first perform all the necessary calculations, especially. It should be remembered that when calculating the value of the machine should be rounded down. For example, with a current load of 20 A, the circuit breaker should be selected for 16 A, which will significantly increase the life of the wiring.

The most common means of protecting lines and electrical appliances are circuit breakers. When installing them, you must follow the basic rules.

Entry at the top of the machine, exit at the bottom.
The enable flag when the machine is on must be directed upwards.
There should be no exposed wire sections.

How to connect a differential machine

The differential circuit breaker combines line protection against overloads and short circuits, as well as circuit breakers, and protection of a person from electric shock, like an RCD.

The case design does not differ from automatic devices or RCDs, which makes it possible to install a differential automatic device in standard boxes using a DIN rail.

Connecting a differential circuit breaker also resembles connecting a circuit breaker with a few exceptions - the mandatory observance of two rules.

It is necessary to observe the phasing of the connected wires. On the case of the differential machine, the designations of the zero and phase inputs are applied, which must be taken into account during installation.
The neutral wire connected at the output of the differential machine is used only with the line that the device protects.

Differential automata are very reliable and unpretentious, but deviation from these rules does not guarantee the correct operation of the device.

For a single-phase network, the use of two-pole machines is preferable to single-pole ones. The reason is simple - when a voltage appears on the neutral wire, one movement of the flag completely breaks the circuit, preserving both the line and the electrical appliances connected to it. The cabinet design of the two-pole switch allows mounting on a standard DIN rail.

It should be borne in mind that the width of such an automatic machine is, as a rule, twice as large as a single-pole machine. The upper contact pair is designed to connect the phase and neutral wires.

There are no strict rules for the location of the phase and neutral wires, but in the case of connecting a number of two-pole machines, it is necessary to adhere to the same tactics.

Choosing, for example, the left contact for the phase wire, all other machines must be connected as well. The left contact is phase, the right one is zero.

The stripped wires are fixed in the contacts using screw clamps. In this case, there should be no bare sections of the wire. Do not forget that there is a very small distance from the phase to the neutral wire and there is a possibility of a short circuit in the absence of insulation.

The most commonly used single-pole circuit breakers are reliable, easy to install and provide the necessary line protection against overloads and short circuits.

When connecting the circuit breaker, it is important that the body of the machine is securely fastened and, when switched on or off, does not fall off the attachment point.

To do this, use a mounting DIN-rail or special boxes with pre-installed rails in the case. The machine is mounted on a rail using a spring-loaded latch at the bottom of the case.

After installing the machine, a wire is connected to it. The upper terminal of the machine is responsible for the voltage input, and the lower terminal for the output. The wires laid and fixed on the wall are led to the machine and stripped.

In this case, it is imperative to comply with the condition of insulation integrity everywhere, except for terminal blocks. The length of the stripped ends is quite enough in 1-1.5 cm.

The phase suitable and outgoing wire is clamped in the terminals of the machine, while the zero wire can pass in transit through the box or, if necessary, fixed on a zero rail.

Laying incoming and outgoing cables in such a way as to avoid excessive lengths. Wires are laid parallel to each other and, if possible, all bends are carried out at right angles.

After installing the machine and checking all connections, the first switching on must be carried out without a connected load on the line.

Greetings to you, dear readers of the site.

In continuation of the series of publications on circuit breakers, the next article in the cycle - circuit breaker connection diagram.

Let me remind you that a series of articles is included in the course.

We have already studied in detail the design and main technical characteristics of the machines, let's look at their connection diagrams.

Depending on the number of switched poles (or otherwise modules), the machines are divided into one-, two-, three-, four-pole (three phases and zero). In the event of an emergency, all poles of the circuit breaker are disconnected simultaneously.

One pole is a part of the machine, which includes two screw terminals for connecting wires (on the supply side and on the load side). The width of a single-pole machine installed on a DIN-rail is standard - 17.5 mm, multi-pole machines are multiples of this width.

Single and double-pole are used in a single-phase power supply. Most often, single-pole machines are used, they are installed in the break of the phase wire and, in the event of an emergency, disconnect the supply phase from the load.

Two-pole machines allow you to simultaneously disconnect both zero and phase. They are used most often as input machines, or if it is necessary to completely disconnect the consumer from the electrical network, for example, a boiler, a shower. They disconnect zero and phase from the protected section of the circuit and allow repair, maintenance or replacement of circuit breakers.

Do not install two single-pole circuit breakers separately to protect the phase and neutral wires. For these purposes, two-pole circuit breakers are used that turn off zero and phase at the same time.

Three- and four-pole are used in a three-phase power network. Three-pole machines are installed in the phase gap (L1, L2, L3) of a three-phase network and are used to connect a three-phase load to it (electric motors, three-phase electric stoves, etc.). In the event of an emergency, they simultaneously disconnect all three phases from the load.

Four-pole machines allow you to simultaneously turn off both zero and all three phases, and are used as input machines in a three-phase power grid.

Allows you to disconnect all electrical wiring of the apartment and disconnect the supply line from the group electrical circuits of the apartment.

Depending on the grounding system, the following input machines are used:

An input circuit breaker for the TN-S system (where the zero working N and the zero protective PE conductors are separated) must be:

- single-pole with zero or two-pole;

- three-pole with neutral or four-pole.

The TN-S system is used in modern homes.

This is necessary for the simultaneous disconnection of the apartment's electrical network from the neutral working and phase conductors from the side of the power supply input, since the neutral and protective conductors are separated throughout.

For the TN-C system (where the zero working and zero protective conductors are combined into one PEN-conductor), the input circuit breaker is installed single-pole (with 220 V power supply) or three-pole (with 380 V power supply). They are installed in the gap of the phase working conductors.

The TN-C system is used in Soviet-built houses (the so-called "two-wire").

According to the rules for the installation of electrical installations (clause 1.7.145), it is not allowed to turn on switching devices in the PE- and PEN-conductor circuits, except for the cases of powering the electrical receivers using plug connectors.

This requirement of the PUE is due to the fact that a situation is possible when two-pole circuit breakers cannot simultaneously disconnect the phase and PEN conductors. And by disconnecting the PEN conductor, we thereby initiate its break.

When switched on under load, inside the machine, sticking or phase contacts may occur (for example, a grain of sand may get on the contact group of the machine), in this case, when the machine is disconnected from the mains, the PEN conductor will break and the dangerous potential will be removed to the zeroed cases of electrical equipment. Those. there is no guarantee that the switching devices will simultaneously disconnect both the phase and the PEN conductor.

The connection of wires to the circuit breakers is carried out according to the scheme: "power supply from above" and "load from the bottom". Those. the supply voltage wire is connected to the upper screw terminal and the outgoing load wire to the lower screw terminal.

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We examined the design, main characteristics, connection diagrams of circuit breakers and came close to the issue of their choice.

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Before proceeding with the installation of automatic switches, it is necessary to determine the operating conditions of the electrical network with its characteristics:

By current;
By voltage;
The electrical power of the appliances to be connected as a load.

The type, characteristics of the selected circuit breaker, respectively, the methods of its installation and connection depend on this.

Purpose and scope of circuit breakers

Circuit breakers are control elements of a switching system and have three main functions:

Conventional switch, on and off;
Disconnection of the load from the mains when the set current threshold is sharply exceeded, this happens in case of a short circuit in the circuit or a malfunction of the load equipment;
Some circuit breakers turn off when the current drops sharply when appliances that consume large amounts of electricity are turned on. To exclude malfunctions on expensive equipment with large surges in voltage and current in the network, the machines disconnect the load.

All these machines have different technical characteristics and design features.

The main types of circuit breakers

Manufacturers make many varieties of different models, despite their design differences.

The appearance of various types of circuit breakers
They all work on the same principle and are designed for the same purpose. When the set current threshold is exceeded, they disconnect the circuit from the power source to save the equipment from overloads.

By purpose, circuit breakers can be divided into the following types:

For switching equipment in lighting, outlet networks, power lines with household equipment of low power;
For switching power supply to electrical installations that are operated in extreme conditions, in an explosive environment, high humidity or dust;
For multiple switching of semiconductor devices in various electronic systems.

By design features, they are divided into three main types:

Air circuit breakers have openings in the body structure through which ventilation of the elements inside takes place. Such models are used in normal dry operating conditions, without fumes and dust;
Molded case switches are used in extreme operating conditions;

Modular switches are one of the airborne options, the design feature is that their dimensions and mounting mechanism are standardized.

The latter option is in the greatest demand among consumers at the household and industrial level. The reason for this popularity is the versatility of these models, ease of installation and connection. Therefore, we will look in detail at how these circuit breakers are connected.

Characteristics and selection criteria for a modular circuit breaker

When choosing a modular circuit breaker, first of all, the following characteristics must be considered:

Breaking capacity maximum measured in kA (kiloAmperes) - this is the current value at which the machine is still operational. The minimum value of this parameter on industrial and household networks is from 3 kA to 10 kA;
Time - current characteristic, sometimes this value is called the sensitivity of the circuit breaker to overcurrent.

In terms of sensitivity, the switches have three classes, B - the circuit breaker is turned off at 3-5 times the rated current for a certain section of the network. С - 5-10 times and D 10 - 20 times, when operating equipment with electric motors, the option of group B is not recommended, short-term starting currents can cause unjustified, frequent trips. The universal option is considered C, for electric motors D.

Rated current section of the network, when a disconnection occurs, circuit breakers are manufactured with values \u200b\u200bin the range of 0.5 - 125 A for modular designs. For industrial input circuit breakers, this value can reach thousands of Amperes.
Number of poleson the switch it can be from 1 to 4, The width of the case of a single module, depending on the product series, 18mm, compact version is half less than 9mm, extended 27mm.

Taking into account these parameters, a choice of switches is made for a specific section of the network, after which a diagram of their connection is drawn up or studied.

Circuit breaker connection diagrams

The classic version of the inclusion of automatic modular switches in the network diagram is carried out when they are placed in the switchboard. Fastening is carried out on a factory din-rail located horizontally inside the board. Wires leading to the load are inserted into the space between the rail and the rear wall of the cabinet. They are connected to the lower output contacts of the machines, to the input, the upper contacts are connected to the wire from the output of the input machine.

A channel is made on the rear wall of the machine under the rail, the upper edge of the body clings to the rail and pressing the frontal plane of the body the lever with a spring fixes the lower part of the body to the rail. The machine is removed from the rail in the reverse order, the lever is pulled back, the lower part of the body is retracted, lifting it up, thus, the entire body is removed from the rail.

Tip # 1 High-power input circuit breakers, not equipped with a DIN rail mount, are separately attached to a metal plate installed in the panel with holes and threads for bolts. Holes in the machine body for attachment to the shield body are provided by the design; self-tapping screws for metal can be used.

Single-pole machines

The connection of single-pole circuit breakers is considered the simplest; they are connected to socket and lighting groups.

Two-pole machines

More powerful devices such as electric stoves, heating boilers, shower cabins, split systems and others, where it is necessary to ensure a complete break in the circuit, the neutral and phase wires are connected through two-pole devices.

Three-pole circuit breakersare used in three-phase networks using powerful devices with a corresponding power supply of 380V. These can be heating elements, electric motors and others. When, when the rated current is exceeded, all three phases are disconnected, thus, phase imbalance in the entire circuit is excluded when the current is exceeded in one of the three lines.

Four-pole circuit breakersconnected to a three-phase network as input automatic devices, where the phases are used as separate lines of the network with individual load elements. In this case, it is necessary to try to distribute the value of the load currents evenly over the phases, in order to avoid phase imbalance. To remove excess currents, a neutral wire is used, a circuit with a grounded neutral.

Connecting circuit breakers in a switchboard requires a lot of knowledge. Firstly, you need to correctly design the wiring, then choose a location, make diagrams, select a case and accessories. After all these procedures, you need to install the equipment, and connect the shield to the cable.

Incorrect connection of the machines can lead to big wiring problems, so it is better to contact an experienced electrician in this matter.

In this article we will talk about the process of correctly connecting the machines to the panel, laying cables and the correct layout of all parts. It is impossible to imagine a modern house without electricity; this issue should be in the forefront.

Electric panel for counter and vending machines - choice of installation location

Let's start with the simplest part - where to place the switchboard in the apartment? It is most convenient to place it near the front door in the hallway. In this case, you do not have to pull the power cable far from the platform. The most optimal height option is at the eye level of an adult. And it is convenient to take meter readings, and turn off the machines if necessary.

For supporters to cram everything under the ceiling, "for greater security, as they say, they used to hang meters", let's say the following. Old electricity meters with plug fuses were simply mounted on the wall without drawers, and therefore hung under the ceiling.

The modern electrical panel has a sturdy housing and is lockable so that children will not get in unless you drop the key in a prominent place.

When choosing a place for mounting the panel in a private house or cottage, you need to consider where and how the cable is or will be started from the overhead line or underground supply line. Data on external networks can be obtained from the local power supply company.

Buy ready-made or assemble an electrical panel with your own hands

As the old song says, "how much progress has come," that you can buy a ready-made shield with a full filling or assemble a ready-made one. If your electrician offers such a “proprietary” build design, don't be alarmed. Shields are assembled by enterprises and electrical installation firms, including on order or for standard projects of apartment wiring.

The main point that needs to be clarified is whether your master has worked with ready-made shields before or this is the first experience. If he has installed a dozen or two of such assemblies and knows their features, then feel free to agree. But if you are a guinea pig for the first experiment, refuse. Better to collect it by hand, in the old fashioned way.

Connection diagram for machines in the dashboard

The scheme of the dashboard in the apartment is one of the main points, but before dealing with it, let's see what elements are included in the design. So that you understand the designations and composition of the wiring diagram.

Introductory machine.

It is put to protect the entire wiring circuit. The cores of the main incoming cable are connected to the terminals of the input machine. For convenient work with the electrical panel, a switch is often installed in front of the input machine.

It allows you to de-energize the entire assembly for replacement of elements, safe prevention and completely cuts off the power supply to an apartment or house. In this case, the power cable is connected to the switch.

Electricity meter.

It is installed after the introductory machine and counts the power consumption in the house or apartment. Sometimes the meter stands separately, up to the dashboard, along with an automatic shutdown. For example, at the site of an apartment building.

Residual current device - designed to protect against electric shock and prevent fires.

The RCD in the circuit can be as one, installed after the meter, for example, in a one-room apartment with a small load. Or they put several RCDs on separate lines with high consumption (on an electric stove, washing machine, air conditioner).

Linear machines.

Needed for separate lines for different rooms, household appliances and lighting. Open the circuit if an overcurrent or short circuit is detected, protect the wiring and connected equipment from damage. The operation of the machine can prevent a fire due to heating and ignition of the wire.

Diffautomat of protection.

It can be installed instead of the automatic + RCD pair on separate power lines of electrical appliances.

DIN rail is a mounting element for installing equipment.

Fastened to the rear wall of the electrical panel housing. Depending on the dimensions of the cabinet, the number of DIN rails and the possible number of installed modules may be different. In order not to be mistaken with the purchase of the shield case according to the number of modules, it is necessary to draw up a wiring diagram.

Connecting busbars.

They are needed to disconnect the electrical panel and connect working zeros and ground wires. The shield uses both zero terminal strips and grounding.

Distribution busbars.

Installed for the "bundle" of linear automata, RCDs, difavtomats. The busbars have reliable insulation and allow you to quickly and safely connect a number of machines through the input terminal block. They can be used for both current conductor and working zero.

What are circuit breakers

These are specially designed devices, the main task of which is to protect the wiring from reflow. In general, machines will not save you from electric shock and will not protect equipment. They are designed to prevent overheating.

short circuit;
excess current flowing through the conductor for this not intended.

As a rule, the machine is installed at the input, that is, it protects the following section of the chain. Since different wiring is used for breeding to different types of devices, it means that protection devices must be able to operate at different currents.

At first glance it may seem that it is enough to install just the most powerful machine and there are no problems. However, it is not. A high current, which has not been triggered by the protection device, can overheat the wiring and, as a result, cause a fire.

What the machine consists of

Cocking handle. With it, you can turn on the machine after it is triggered, or turn it off to de-energize the circuit.
Activation mechanism.
Contacts. Provides connection and circuit breaking.
Terminals. They are connected to the protected network.
Conditionally triggered mechanism. For example, a bimetallic heat plate. Many models may have an adjusting screw to adjust the nominal current.
Arc-extinguishing mechanism. Present at each pole of the device. It is a small chamber with copper-plated plates. On them, the arc is extinguished and disappears.

Depending on the manufacturer, model and purpose, the machines can be equipped with additional mechanisms and devices.

Shutdown mechanism device

The machines have an element that breaks the electrical circuit at critical current values.

Electromagnetic devices. They are characterized by a high speed of reaction to a short circuit. Under the action of currents of an unacceptable value, a coil with a core is triggered, which, in turn, disconnects the circuit.
Thermal. The main element of such a mechanism is a bimetallic plate, which begins to deform under the load of high currents. Bending, has a physical effect on the element breaking the chain.

An electric kettle works in approximately the same way, which is able to turn itself off when water boils in it. There are also semiconductor circuit breakers. But they are rarely used in household networks.

Time-current characteristics of circuit breakers

Devices differ in the nature of operation for an excessively high current value. There are 3 most popular types of machines - B, C, D.

B (3 to 5 xln);
C (5 to 10 xln);
D (10 to 20 xln).

What does it mean? It's very simple - to understand the range at which the machine is capable of triggering, you need to multiply the figure next to the letter by the xln value.

16 * 3 \u003d 48A;
16 * 5 \u003d 80A.

the machine marked B16 will shut down in the range 48 ... 80A;
marked C16 will shut down in the range 80 ... 160A;
and marked D16 will shutdown in the range 160… 320A.

The most common type of machine is C, it is used in almost every home.
Circuit breakers marked D are mainly used in places with consumers that have high starting currents, such as electric motors.
Type B is the most sensitive, rarely used, mainly for the protection of electronic equipment. And it costs accordingly more.

At a current of 100 A, the B16 machine will turn off almost instantly, while the C16 will not turn off immediately, but after a few seconds from thermal protection (after its bimetallic plate heats up).

Legend

Different types of machines are marked in their own way for quick identification and selection of the one needed for a particular circuit or its section. As a rule, all manufacturers adhere to one mechanism, which allows unifying products for many industries and regions.

Brand. Usually, the manufacturer's logo is placed at the top of the machine. Almost all of them are stylized in a certain way and have their own corporate color, so it will not be difficult to choose a product for your favorite company.
Indicator window. Shows the current status of contacts. If there is a malfunction in the machine, then it can be used to determine whether there is voltage in the network.
Machine type. As already described above, means the tripping characteristic at currents significantly higher than the rated one. C is used more often in everyday life and B. The differences between the types of electrical machines B and C are not so significant;
Rated current. Shows the current value that can withstand continuous load. Rated voltage. Very often this indicator has two meanings, written with a slash. The first is for a single-phase network, the second is for a three-phase network. As a rule, in Russia the voltage is 220 V.
Cut-off current limit. It means the maximum permissible short-circuit current at which the machine will shut off without failure. Current limiting class. Expressed in one digit or absent at all
Scheme. On the machine, you can even find a connection diagram for contacts with their designations. It is almost always located in the upper right part. Thus, by looking at the front of the machine, you can immediately establish what type of current it is intended for and what it is capable of.

What type of machine to choose

When choosing a protective device, it is the rated current that is considered one of the main characteristics. To do this, you need to determine what current strength is required by the totality of all consumer devices in the house.

And since electricity flows through the wires, the current strength required for heating depends on its cross section. The presence of poles also plays an important role.

One pole. Chains with lighting devices and sockets to which simple devices will be connected.
Two poles. It is used to protect the wiring to electric stoves, washing machines, heating devices, water heaters. It can also be installed as a protection between the shield and the room.
Three poles. Used primarily in three-phase circuits. This is true for industrial or near-industrial premises. Small workshops, production facilities and the like.

The tactic of installing machines comes from more to less. That is, it is first mounted, for example, two-pole, then single-pole. Next come devices with power decreasing at each step.

The first thing to start with is the correct connection of the machine in principle. As you know, the circuit breaker has two contacts for connecting movable and fixed.

On which of the pins do you need to connect the power to the top or bottom? To date, there have been a lot of controversies on this matter. On any electrotechnical forum there are a lot of questions and opinions on this matter.

Let's turn to the regulatory documents for advice. What does the PUE say about this? 7th edition PUE clause 3.1.6. said:

3.1.6. Circuit breakers and plug type fuses must be connected to the network so that when the fuse (circuit breaker) plug is unscrewed, the screw fuse (circuit breaker) sleeve remains de-energized. With one-sided power supply, the connection of the supply conductor (cable or wire) to the protection device should be carried out, as a rule, to fixed contacts.

As you can see in the rules, it is said that the supply wire when connecting the machines in the shield must be connected, as a rule, to fixed contacts. This also applies to all RCDs, difavtomats and other protection devices. The expression "as a rule" is not clear from this whole clipping. That is, it seems, as it should, but in some cases there may be an exception.

To understand where the movable and fixed contact is located, you need to imagine the internal structure of the circuit breaker. Let's look at the example of a single-pole machine where the fixed contact is located.

Before us is an automatic machine of the BA47-29 series from iek. It is clear from the photo that the fixed contact is the upper terminal, and the moving contact is the lower terminal. If we consider the electrical designations on the switch itself, then it is also clear here that the fixed contact is on top.

Circuit breakers from other manufacturers have similar markings on the case. Take, for example, an automatic machine from Schneider Electric Easy9, it also has a fixed contact on top. For Schneider Electric RCDs, everything is similar on top there are fixed contacts, and on the bottom there are movable ones.

Another example is Hager safety devices. On the case of the hager circuit breakers and RCDs, you can also see the designations, from which it is clear that the fixed contacts are on top.

Let's see if it matters from the technical point of view how to connect the machine from above or below.

The circuit breaker protects the line against overloads and short circuits. When overcurrents appear, the thermal and electromagnetic release located inside the housing react.

From which side the power will be connected from the top or from the bottom for tripping the releases, there is absolutely no difference. That is, we can say with confidence that the operation of the machine is not affected by which contact will be supplied with power.

In truth, I must say that manufacturers of modern "branded" modular devices, such as ABB, Hager and others, allow connecting the power to the lower terminals. For this, the machines have special clamps designed for comb tires.

Why, in the PUE, it is advised to connect to fixed contacts (upper)? This rule is approved for general purposes. Any educated electrician knows that when performing work, it is necessary to remove voltage from the equipment on which he will be working.

"Climbing" into the switchboard, a person intuitively assumes the presence of a phase on top of the machines. Having disconnected AB in the shield, he knows that there is no voltage at the lower terminals and everything that leaves them.

Now let's imagine that the connection of the machines in the switchboard was performed by an electrician, Uncle Vasya, who connected the phase to the lower contacts AB.

Some time has passed (week, month, year) and you need to replace one of the machines (or add a new one). Uncle Petya, an electrician, comes in, turns off the necessary machines and confidently climbs under tension with his bare hands.

In the recent Soviet past, all machines had a fixed contact at the top (for example, the AP-50). Now, by the design of modular AB, you cannot tell where is the movable, and where is the fixed contact. For AB, which we considered above, the fixed contact was located on top. And where are the guarantees that the Chinese machines will have a fixed contact located on top.

Therefore, in the rules of the PUE, the connection of the supply conductor to fixed contacts implies only connection to the upper terminals for the purposes of general order and aesthetics. I myself am a supporter of connecting power to the top contacts of the circuit breaker.

For those who disagree with me, the question is about filling, why in electrical circuits, the power to the machines is connected to fixed contacts.

If we take, for example, a conventional RB-type switch, which is installed at every industrial facility, then it will never be connected upside down. The connection of power to switching devices of this kind is supposed to be connected only to the top contacts. I turned off the switch, and you know that the lower contacts are without voltage.

Connection of circuit breakers

After the machine is selected, it must be connected. Connecting circuit breakers is not a difficult task and everyone can do it.

Automatic switches are installed in the box for electrical machines. To securely fix the machine in the electrical panel, it is placed on a special din-rail. The wires in the terminal clamps of the machine are fixed with bolted contacts.

During installation in electrical panels and connecting supply or outgoing lines, it is necessary to tighten the bolt contacts carefully, without excessive force.

The tightening of the contacts should not be accompanied by deformation of the machine case, as this can lead to a violation of the positions of the current-carrying parts inside the machine case, which can cause excessive overheating of the machine and its failure even with minor loads.

When connecting the machine, it is necessary to follow the generally accepted rule: the input (power) is connected from the top of the machine, and the output (load) is connected from the bottom.

In the future, when it becomes necessary to replace or connect additional wires to the working machine, you will always know to which contact the load and power are connected.

Before connecting the conductors of the cable to the terminals of the machine, the external insulation of about 10-15 cm is removed from it, after which the cable becomes more flexible and easily bends inside the electrical panel. This simplifies installation, especially if many machines are installed in the switchboard. Further, the internal insulation is removed from the wires by about 5-10 mm.

For the need to connect small wires or stranded wires to the machine, it is advisable to use special terminals.

Where are used and how are one-, two-, three- and four-pole machines connected

In single-phase networks with a voltage of 220 V, single-pole or double-pole machines are usually installed to protect electrical appliances.

Only the phase wire is connected to single-pole circuit breakers - L.
Both wires are connected to two-pole, phase - L and neutral wire - N.
Three-pole circuit breakers are used in 3-phase networks. Three phases of the power supply L1, L2, L3 are connected to the terminals of such machines.
Four-pole machines are used in places determined by the rules of the PUE. As a rule, these are four-wire networks with a dead-grounded neutral, in which three phases L1-L2-L3 are used and a zero working one - N (TN-S system).

Main mistakes when connecting machines

connection of the ends of the conductors of a flexible stranded wire without termination;
contact with insulation;
connection of conductors of different cross-sections per terminal;
soldering of the ends.

The main mistake when connecting the machines is the use of a flexible stranded wire without termination. It's easier and faster this way, but not right. Such a wire cannot be clamped securely; over time, the contact weakens ("flows"), resistance increases, and the junction heats up.

It is necessary to use lugs for flexible wire or use a solid solid wire for installation.

Everyone knows that before connecting the machine in the dashboard, you need to remove the insulation from the connected wires. It would seem that there is nothing complicated here, stripped the core to the required length, then insert it into the terminal block of the machine and tighten it with a screw, thereby ensuring reliable contact.

But there are cases when people are at a loss why the machine burns out when everything is connected correctly. Or why the power in the apartment periodically disappears when the wiring and filling in the dashboard are completely new.

One of the reasons for the above is that the wire insulation gets under the terminal of the circuit breaker. Such a danger in the form of poor contact carries a threat of melting of the insulation, not only of the wire, but also of the machine itself, which can lead to a fire.

To exclude this, you need to follow and check how the wire is tightened in the socket. The correct connection of the circuit breakers in the switchboard should exclude such errors.

Never connect the machines with jumpers with cables of different cross-sections. When tightening the contact, a conductor with a large cross section will be well clamped, and the conductor with a smaller cross section will have poor contact. As a result, the insulation melts not only on the wire, but also on the machine itself, which will undoubtedly lead to a fire.

The first machine receives a "phase" with a 4 mm2 wire,
and other machines already have 2.5 mm2 jumpers.

As a result, poor contact, temperature rise, insulation melting not only on the wires, but also on the machine itself.

For example, let's try to tighten two wires with a cross section of 2.5 mm2 and 1.5 mm2 in the terminal of the circuit breaker. No matter how hard I tried to provide reliable contact in this case, nothing worked for me. A wire with a cross section of 1.5 mm2 dangled freely and sparked.

Separately, I would like to dwell on such a method of terminating wires in the shield as soldering. Human nature is so arranged that people try to save money on everything and do not always want to spend money on all kinds of tips, tools and all kinds of modern small things for installation.

For example, consider the case when Uncle Petya, an electrician from the housing office, conducts the electrical panel wiring with a stranded wire (or connects outgoing lines to an apartment). He does not have NSHVI tips. But there is always a good old soldering iron at hand.

And the electrician Uncle Petya does not find any other way out how to irradiate the multi-wire conductor, stuffs the whole thing into the contact terminal of the machine and tightens it heartily with a screw. Why is such a connection of machines in a switchboard dangerous?

When assembling switchboards, DO NOT solder or service the stranded conductor. The fact is that the tinned compound begins to "float" over time. And for such a contact to be reliable, it constantly needs to be checked and tightened. And as practice shows, this is always forgotten.

The soldering begins to overheat, the solder melts, the junction is weakened even more and the contact begins to "burn out". In general, such a connection can result in a FIRE.

How to properly connect an electric meter and machines

use a single-wire monolithic wire for installation;
use ferrules when using flexible wires;
use non-breaking jumpers;
use a U-fold to increase the contact area.

Using lugs on flexible wires

For wiring switchboards, electricians often prefer a flexible wire with a multi-wire conductor of the PV-3 or PuGV type. It is easier and easier to work with it than with a monolithic vein. But there is one peculiarity here.

The main mistake that beginners make in this regard is to connect a stranded wire to the machine without termination. If you clamp the bare stranded wire as it is, then when tightening the veins are squeezed and break off, and this leads to a loss of cross-section and deterioration of contact, and the contact itself has been weakening from time to time.

Experienced "experts" know that it is impossible to tighten the bare stranded wire in the terminal. Therefore, if a stranded wire is used during installation, then NSHV or NSHVI tips must be used to terminate it.

In addition, if there is a need to connect two stranded wires to one terminal of the machine, for this you need to use a double lug NSHVI-2. It is very convenient to use it to form jumpers for connecting several group machines.

Using the U-fold

To connect the veins of outgoing wires and cables to the machines, we remove the insulation from them by about 1 cm, insert the bare part into the contact and tighten it with a screw. According to statistics, 80% of electricians are connected this way.

The contact at the junction is reliable, but it can be further improved without wasting time and money. When connecting cables with a solid core to the machines, make a U-bend at the ends.

This formation of the ends will increase the contact area of \u200b\u200bthe wire with the terminal surface, which means the contact will be better.

The inner walls of the contact pads AB have special notches. When the screw is tightened, these notches cut into the core, which increases the contact reliability.

If it becomes necessary to connect several machines standing in the same row from one source (wire), a comb bus is the best fit for this purpose. But these tires are not always at hand.

How can several group machines be combined in this case? Make a homemade jumper from the cable cores. To do this, use pieces of wire of the same cross-section, or it is better not to break it at all along its entire length.

Without removing the insulation from the wire, form a jumper of the desired shape and size (by the number of branches).
Then we strip the insulation from the wire at the bend to the desired length, and we get an unbreakable jumper from a single piece of wire.