Selection of circuit breakers. What is rated current in electrical engineering Current series of circuit breakers

It is probably not worth reminding that modern electrical networks experience overloads that negatively affect the networks themselves. Therefore, for protection, automatic switches are installed, or as they are commonly called – automatic machines. They are the ones who turn off the power supply to the network if there is an overload. But here another question arises regarding the parameters of these machines, where two main ones stand out: the current ratings of the circuit breakers and the time-current characteristic. Let's understand these indicators.

Current ratings of machines

Let's start with the fact that all the characteristics of circuit breakers are located on their body. Therefore, finding them is not a problem. As for the rated current of the machine, electricians consider it the main characteristic. Essentially, this is the maximum current value that the machine can withstand without turning off the power supply. As soon as the actual current exceeds the rated current, the machine will operate and turn off the circuit.

It should be immediately noted that the ratings of circuit breakers are standardized, that is, they have certain digital values. This is the standard range: 6, 10, 16, 20, 25, 32, 40, 50, 63, 80, 100 A. Some European manufacturers produce devices with a rating of 125 amperes.

Attention! All these values ​​must be indicated on the body of the machine itself, and they are valid at an ambient temperature of +30C. That's how it happened.

It is the operating temperature that affects the current load of the machine. And the higher the temperature in this case, the lower the current load this protective device can withstand. There is one more point that determines the method of installing the machines. Usually in a distribution board they are installed next to each other, pressed tightly. Each circuit breaker generates heat during operation because electricity passes through it. Therefore, each device acts on the neighboring one, increasing the temperature of the latter. Moreover, the larger the device in terms of current rating, the more thermal energy it emits.

It should be noted that many manufacturers of circuit breakers in their product catalogs necessarily indicate correction factors with which you can correctly calculate the current rating depending on the ambient temperature. This makes it easier to make the right choice.

And that is not all. Some household appliances emit so-called inrush current when turned on. It is usually five to six times higher than the nominal value, which again will affect the increase in load in the supply network. True, such currents are short-term and they have no effect on the cable, but the machine can react to them. True, everything will depend on the second characteristic of this device - time-current.

What does this physical indicator mean? In principle, everything is quite simple. When the network is overloaded, especially when the load depends on the starting torque of the household appliance, the machine turns off. But since this load is short-term, sometimes there is no need to turn off the power supply. It turns out that the machine allows the device to turn on, and at the same time it does not cut off the supply of electricity to the electrical wiring of the building.

But there is one caveat. How long does it take for a household appliance to enter normal operating mode, and how quickly does it turn on? That is, how long will the inrush current last? It is the time indicator that is included in this characteristic of the circuit breaker. This creates conditions under which the shutdown of the machine will be reduced.

There are several machines with different time-current loads.

• Type-A. This device is used in linear networks in which the length of the electrical wiring is very long, or where semiconductor devices are installed. Withstands overload 2-3 times.
• Type-B. Usually installed in a network with an active load and a low multiplicity of the starting current torque. Typically, such machines are used in areas where lighting, stoves, heaters, and so on are installed. Overload is 3-5 rated loads.
• Type-S. Mounted in networks with moderate current loads. These are usually socket groups where air conditioners and refrigerators are connected. Withstands exceeding the nominal value by 5-10 times.
• Type-D. Used in circuits where units with high starting current are installed. These can be compressors, pumps, small machines. The excess is 10-20 denominations.
• Type-K. used in electrical circuits with inductive loads. Excess: 8-12.
• Type-Z. Such machines are installed in circuits into which electronic devices are connected. They are sensitive to overcurrents.

If we talk about domestic use, then most often types “B” and “C” are installed in electrical wiring, rarely “D”.

So, how to determine both characteristics on the circuit breaker itself? Usually on the case you can find the following designation: “C16” or any other, the main thing is that it is a letter of the Latin alphabet and a number. This indicates (in this case) that the current rating of the circuit breaker is 16 amperes, and the time-current characteristic classifies this device as type “C”. That is, this machine will withstand a current of 80-160 amperes for some time. Typically, the response time of the machine is 0.1 seconds.

Calculation

How to calculate the rated current of a circuit breaker? Everything is quite simple. Let's look at this calculation using the example of a socket group where an electric kettle with a power of 1.5 kW, a refrigerator with a power of 400 W and a dishwasher with a power of 2.5 kW are connected.

First of all, it is necessary to determine the total power of consumers, which is equal to 4.4 kW. Now we insert all the indicators into the formula of Ohm’s law:

I=P/U=4400: 220=20 A. We have a machine with such a current load in our catalog, but it is necessary to take into account the conditions that were specified in the article above. That is, it is better to choose a circuit breaker with a higher current rating. And this will be 25 amperes.

When assembling an electrical panel or when connecting powerful household appliances to the home network that create additional load, the master is faced with the task of correctly selecting automatic protective devices. These devices provide protection for the circuit and all elements included in it, so it is important not to make a mistake in choosing. How to choose the correct current ratings of circuit breakers? This will be discussed in the presented material.

Purpose of the circuit breaker

Before we figure out the question of how to choose a circuit breaker, let’s decide what this device is needed for. Installing the machine in an electrical circuit helps prevent overheating of the wiring and its failure. Any cables are designed for a certain amount of current, exceeding which leads to the fact that the temperature of the wire increases significantly. If this is not prevented in a timely manner, the conductor will soon begin to melt. The result, as a rule, is a short circuit (SC), which can not only damage the electrical wiring and household appliances connected to it, but also cause a fire.

To prevent this, an automatic circuit breaker (AB) is installed, which will de-energize the network if a dangerous situation occurs.

Another function of the circuit breaker is to turn off the power when a short circuit has already occurred for any reason.

The short circuit current can be hundreds of times higher than the rated current. Neither wires nor home appliances can withstand such a load, and it is very important to turn off the power in a timely manner as soon as the current exceeds the permissible limit.

To reliably protect your home network, it is necessary to correctly select the ratings of circuit breakers installed in an apartment or private house.

Video about circuit breakers:

Types of protective devices

There are several types of AVs that are connected to the network in order to monitor the condition of the wiring and, if necessary, stop the current supply. They may be as follows:

• Mini models (small in size).
• Air (open type).
• Residual current devices (abbreviated name - RCD).
• Closed (device elements are housed in a molded housing).
• Differential (circuit breakers combined with RCD).

Mini models

These devices are designed to operate in circuits where the load is low. They usually do not have additional adjustment functions. This series includes devices that can withstand a misfire current of 4.5 - 15A. They are not suitable for factory power, since the current strength in enterprises is much higher than their nominal value. Therefore, they are usually connected to household wiring.

The machines included in the product line of the French company Schneider Electric are very popular. The ratings of the AVs produced by this company can be 2 - 125A, so you can choose a package for home lines of various powers.

Air (open) devices

If the total power of the devices connected to the network is large, and the ratings of the machines mentioned above are insufficient, air protective devices should be chosen. The rated cut-off current of open-type bags is an order of magnitude higher than that of mini-models. Most often they are three-pole, but recently many companies have started producing four-pole machines.

Open type protective devices should be installed in distribution cabinets equipped with special DIN rails on the inside.

If the cabinet's protection class is IP55, then it can be placed outside the building. The body of this equipment is made of refractory metal and is reliably protected from moisture penetration, which ensures a high level of safety for the machines located inside it.

Airborne ABs have a great advantage over miniature ones. It lies in the ability to customize their nominal characteristics using special inserts that are placed on the active contact.

The machines belonging to this model range differ from each other only in width, depending on the number of poles in the device (two or more). In other dimensions they are completely identical.

Enclosed circuit breakers

The body of these devices is cast from refractory metal, which ensures their perfect tightness and makes them suitable for use in harsh conditions. The maximum voltage that such machines can withstand is 750V, and the current is 200A. Closed AVs are classified according to the type of action into the following groups:

• Adjustable.
• Thermal.
• Electromagnetic.

The optimal type should be selected based on the tasks being solved.

The highest accuracy is achieved by electromagnetic closed circuit breakers, which determine with a minimum error the root mean square indicator of the active electric current and instantly de-energize the network in the event of a short circuit, avoiding serious consequences.

Electromagnetic machines are successfully used to control the functioning of motors in factory machines, as well as other powerful equipment, since they can withstand currents of up to 70 kA. The number indicating the current rating of the circuit breaker is printed on its body.

All types of enclosed switches can have two to four poles. Thanks to this, they can be used to protect electrical networks of any residential and non-residential buildings and structures.

Residual current devices

Residual current devices should not be used as independent protective devices, since their main task is to protect people from sudden electric shock. Therefore, it is recommended to install them together with the automatic circuit breaker, or to purchase a differential circuit breaker that already includes an RCD. In the first case, you need to take into account that the residual current device should be installed first, and then the circuit breakers.

If you change the installation order, a short circuit will lead to failure of the RCD as a result of too high a load.

How to choose a wire?

It is not uncommon that a new circuit breaker and meter are connected to the electrical wiring of an old house, an RCD is installed, but the cable itself is not changed. The choice of current circuit breaker is made correctly, taking into account the total power of household appliances installed in the house. But after some time, the insulation begins to smoke and melt, and the protective device does not respond to this.

The reason is that, although the choice of circuit breaker and related devices was made correctly, the electrical wiring is not able to withstand such a load.

Therefore, when connecting additional household appliances, you must make sure that the wiring cross-section is suitable for such power.

Below is a table according to which you can find out what the wire cross-section should be under various loads.

Rated current calculation

The selection of a circuit breaker is made taking into account the total power of electrical appliances included in the circuit (P) and the network voltage (U), according to the formula I=P/U. This takes into account all elements included in the electrical network (lighting fixtures, household appliances, electric heaters). For convenience and clarity, we present one more plate, by checking which you can easily determine how many Amperes to set the machine in a given case. It contains parameters for both single-phase and three-phase connections.

For powerful electrical installations that have a reactive load (this includes transformers, electric motors), the selection of circuit breakers is not made based on the power indicator. The rating of the protective device in this case is selected based on the value of the operating and starting current. These data are given in the technical data sheet of the device.

An example of calculating the rated current for a circuit breaker in the following video:

Conclusion

In this article, we talked about why electrical network protection devices are needed, what types of these devices are, and also figured out how to correctly select the current ratings of protective circuit breakers. This information will be useful to you if you need to select machines for your apartment or private house.

Automatic switch IEK. Thermal current – ​​32 A

A circuit breaker has several other names among people - circuit breaker, plug, bag, or simply circuit breaker.

What we are talking about is in the picture on the left. This is the most budget model.

This article will discuss the technical characteristics of circuit breakers, what they are, and how to choose them in various cases.

We can absolutely say that anyone who carefully reads this article can be considered an expert on circuit breakers. At least to a first approximation, sufficient for practical work and understanding of processes.

I have already written several articles on this topic on the blog, and I will post links along the way.

Circuit breaker functions

From the name it is clear that this switch, which turns off automatically. That is, myself, in certain cases. From the second name - circuit breaker - it is intuitively clear that this is some kind of automatic device that protects something.

Now more details. The circuit breaker trips and turns off in two cases - in case of overload by current, and in the case short circuit (short circuit).

Overcurrent occurs due to faulty consumers, or when there are too many consumers. Short circuit is a mode when all the power of the electrical circuit is spent on heating the wires, while the current in this circuit is the maximum possible. More details will follow.

In addition to protection (automatic shutdown), machines can be used to manually turn off the load. That is, like a switch or a regular “advanced” switch with additional options.

Another important function (this goes without saying) is the connection terminals. Sometimes, even if the protection function is not particularly needed (and it never hurts), the terminals of the circuit breaker can be very useful. For example, as shown in the article.

Number of poles

Depending on the number of poles, the machines are:

1. Single pole(1p, 1p). This is the most common type. It stands in a circuit and protects one wire, one phase. This is shown at the beginning of the article.
2. Bipolar(2p, 2p). In this case, these are two single-pole circuit breakers, with a combined switch (handle). As soon as the current through one of the machines exceeds the permissible value, both will turn off. These are mainly used to completely disconnect a single-phase load when both the zero and the phase break. It is the two-pole circuit breakers that are used at the entrance to our apartments.
3. Three-pole(3p, 3p). Used to break and protect three-phase circuits. Just as in the case of two-pole ones, these are actually three single-pole circuit breakers, with a common on/off handle.
4. Four-pole(4p, 4p). They are rare, they are installed mainly at the input of three-phase switchgears (switchgears) to break not only the phases (L1, L2, L3), but also the working zero (N). Attention! Under no circumstances should the protective grounding (PE) wire be broken!

Circuit breaker current

Automatic currents come from the following series:

0,5, 1, 1,6, 2, 3,15, 4, 5, 6 , 8, 10 , 13, 16 , 20, 25 , 32 , 40 , 50, 63.

The denominations most often used in everyday life are highlighted in bold. There are other denominations, but we won’t talk about them now.

This current for the circuit breaker is rated. If it is exceeded, the switch will turn off. True, not immediately, as stated below:

Time-current characteristics

Obviously, the machine does not always turn off instantly, and sometimes it needs to “think and make a decision”, or give the load a chance to return to normal.

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The time-current characteristic shows after what time and at what current the machine will turn off. These characteristics are also called tripping curves or current-time characteristics. Which is more accurate, since it depends on the current after what time the machine turns off.

Tripping curves or current-time characteristics

Let me explain these graphs. As I said above, the circuit breaker has two types of protection - thermal (against overcurrent) and electromagnetic (against short circuit). In the graph, the operation of thermal protection is a section that smoothly descends. Electromagnetic – the curve abruptly breaks down.

The thermal one works slowly (for example, if the current is twice the nominal value, the machine will go out in about a minute), and the electromagnetic one works instantly. For graph IN this instant “starts” when the current exceeds the nominal value by 3-5 times, for the category WITH– 6-10 times, for D(not shown because it is not used in everyday life) - 10-20 times.

How it works - you can imagine what will happen if the current exceeds the nominal value by 5 times, and the protection is with the “C” characteristic, as in all houses. The machine will only go off after 1.5-9 seconds, depending on your luck. In 9 seconds the insulation will melt and the wiring will need to be changed. In this case, therefore, short circuit is better than overload.

Selecting a circuit breaker. Basic Rule

It is necessary to select a circuit breaker based on the cross-sectional area of ​​the wire that this circuit breaker protects (which is connected after this circuit breaker). And the cross-section of the wire is based on the maximum current (power) of the load.

The algorithm for selecting a circuit breaker is as follows:

1. We determine the power and current of the line consumers that will be fed through the machine. The current is calculated using the formula I=P/220, where 220 is the rated voltage, I is the current in amperes, P is the power in watts. For example, for a 2.2 kW heater the current will be 10 A.
2. Select the wire according to the table. A cable with a conductor cross section of 1.5 mm² is suitable for our heater. In the worst conditions in a single-phase network, it holds a current of up to 19A.
3. We choose a machine so that it is guaranteed to protect our wire from overload. For our case - 13A. If you install a machine with such a rated thermal current, then at a current of 19A (one and a half times higher), the machine will work in about 5-10 minutes, judging by the time-current characteristics.

Is it a lot or a little? Considering that the cable also has thermal inertia and cannot instantly melt, this is normal. But considering that the load cannot just increase its current by one and a half times, and in these minutes a fire can occur - this is a lot.

Therefore, for a current of 10 A, it is better to use a wire with a cross-section of 2.5 mm² (the current with an open installation is 27 A), and a 13 A machine (if it is exceeded by 2 times, it will work in about a minute). This is for those who want to play it safe.

The main rule will be this:

The wire current must be greater than the current of the machine, and the current of the machine must be greater than the load current

Iload< Iавт < Iпров

This refers to maximum currents.

And if there is such a possibility, the rating of the machine should be shifted towards the load current. For example, the maximum load current is 8 Amperes, the maximum wire current is 27A (2.5mm2). The machine should be chosen not for 13 or 16, but for 10 Amperes.

Here is the machine selection table:

Table for selecting a circuit breaker based on cable cross-section

The choice of circuit breaker clearly depends on the cable cross-section. If the current of the machine is selected more than necessary, then the cable may overheat due to the flow of high current. If the machine is selected correctly, then if the current exceeds it will turn off and the cable will not be damaged.

Pay attention to the cable routing methods (installation type). Depending on where the cable is laid, the current of the selected circuit breaker may differ by 2 times!

According to the table, we have the initial cable cross-section, and select a circuit breaker for it. For us, as electricians, the first three columns of the table are most important.

Now - how to choose a circuit breaker if the power of the devices is known?

Table for selecting a circuit breaker based on load power

Table of consumption and current of the circuit breaker according to the power of devices

It can be seen that the manufacturer recommends different time-current characteristics for different electrical appliances. Where the load is purely active (different types of heaters), the characteristics of the machine “B” are recommended. Where there are electric motors - “C”. Well, where powerful engines with difficult starting are used - “D”.

Table of dependence of the current of the circuit breaker (fuse) on the cross-section

And here is how the Germans treat the circuit breaker current depending on the cross-sectional area of ​​the wire:

As you can see, the Germans are playing it safe and are providing for a larger reserve compared to us.

Although, perhaps this is because the table was taken from instructions from “strategic” industrial equipment.

How does a circuit breaker work?

A bonus is the device of the protective circuit breaker, several photos of the circuit breaker, which is given at the beginning of the article.

Circuit breaker device. As you can see, the device is not simple. Upper (fixed) contact – right

Circuit breaker. One second before the trash can)

As always, I will be glad to have questions and comments on the article in the comments!

The main characteristic of automatic protective equipment is the rated currents of the circuit breakers. This parameter is displayed on the device body along with the manufacturer's trademark and serial number. This value represents the maximum. The time for this current to flow through the circuit breaker can be infinitely long, without disconnecting the protected circuit. If the nominal value is exceeded, the machine is triggered and the protected circuit is opened.

Machine parameters

The main current ratings are standardized and represent the following range of values: 6, 10, 16, 20, 25, 32, 40, 50, 63, 80 and 100 amperes. These values ​​correspond exactly to their value when the temperature surrounding the machines does not exceed 30 degrees. If the temperature increases, the corresponding rated current will decrease.

This can happen when several devices are installed in an electrical panel at a very close distance from each other. Mutual heating occurs, as a result of which the value of the switched electric current decreases. In order to take this error into account, special correction factors can be used.

When several consumers are connected to the network at once, inrush currents may arise for a short time, many times exceeding the rated current of the circuit breaker. To avoid spontaneous shutdowns at such moments, it is practiced to use automatic machines with different time-current characteristics.

Time-current characteristic

When considering the rated currents of automatic machines, we must not forget about the time-current characteristic of their operation. Here the time of switching off the circuit and the strength of the current flowing through it depend. The actual flowing electric current is correlated with the nominal current and shows how many times it exceeds it. That is, with the same current, shutdown can occur in different ways.

There are several types of circuit breakers, depending on the time-current characteristics. Each type shows how many times it exceeds the current value. The scope of application of this or that type of circuit breaker also depends on this.

In some device models there is a C marking, meaning the ability to release as quickly as possible. This characteristic of the machines is a graph where the rated current is indicated horizontally, and the operating time of the device is indicated vertically.

Selecting a circuit breaker

Circuit breakers

Definition: (This definition of a circuit breaker is in GOST R 50030.2.)

Automatic switch (abbreviated as switch or allegorically automatic) - mechanical switching device , allowing you to turn on, pass and turn off electric current under normal conditions; turn on and pass electrical energy for a specified period of time and disconnect a circuit under certain abnormal circuit conditions.

Purpose:

(functionality (application) of a circuit breaker)

1. Protection function.

The circuit breaker serves to protect electrical networks and various energy consumers from short circuit currents (SC) and overload, as well as from unacceptable voltage drops.
To protect against short circuits, an electromagnetic release can be used (in switches from 630A and above, semiconductor or electronic releases).
For protection in the overload zone, a thermal release is used (for circuit breakers from 630A or more, semiconductor or electronic releases are used for this purpose).
To protect against unacceptable voltage drops, an undervoltage release or a zero-voltage release (optional) is activated.

2. Control function.

Automatic switches allow manual and automatic infrequent operational switching on/off of the circuit.
For manual switching, the manufacturer sets the number of operating cycles for a certain time. Often, the higher the amperage of the circuit breaker, the fewer switching operations are allowed.
To remotely control the network, the switch must be equipped with an independent release (an additional custom option) or an electromagnetic drive.

3. Role of circuit breaker.

Reusable object protection. The fuse provides only one-time protection (afterwards you need to change the melted insert or replace the fuse itself). Although the switch implies control of the circuit, a switch is usually installed for these purposes. The contact group of the switch tolerates a limited number of switchings, and the cost of the switch is much lower.

Regulatory documents (GOST) according to which low-voltage circuit breakers are produced

We list the standards that regulate the production and testing of low-voltage circuit breakers:
GOST R 50345-99 - standard for household circuit breakers (original translation of the international standard IEC 60898).
GOST R 50030.2-99 - standard for industrial circuit breakers (original Russian translation of IEC 60947.2).
GOST 9098-78 is a regulatory document for low-voltage air circuit breakers (the current Union standard).

IEC (English abbreviation IEK) - International Electrotechnical Commission.

Classification of circuit breakers:

Circuit breakers can be classified according to the following characteristics (not a complete list of parameters is given, but a partial one):

1. By application category: A and B.
A - non-selective circuit breakers (operation at short-circuit currents occurs without a time delay);
B - selective circuit breakers (in short-circuit conditions a short-term specified time delay is provided).

Selectivity:

Overcurrent selectivity is when, when connecting two circuit breakers in series, designed to protect against short circuits, the load-side circuit breaker disconnects the contacts without tripping the second circuit breaker.

The meaning of selectivity:

Switches with rated currents from 1000A are selective; they are installed in front of an industrial complex, they protect further branching circuits and energy consumers. Let's assume that a short circuit occurs in one of the branches of the circuit; when a switch of 1000 A or higher is automatically activated, the entire object will be completely cut off. To prevent this, this machine is given selectivity, that is, a certain period of time is set after which (just in case) it will work. And during this time, a circuit breaker with a lower amperage is triggered, which will turn off the specific branch with the resulting short circuit. In this case, the industrial facility operates without one branch, the selectivity switch does not operate.

2. By type of current: direct current, alternating current; for alternating and direct currents.
An example of an AC circuit breaker: AE 2056 circuit breaker.
An example of a circuit breaker for alternating and direct currents: circuit breaker BA 04 36.

Range (line) of rated currents for low-voltage circuit breakers (numbers - switch amperage):

1.6A; 2.5A; 4A; 6.3A; 10A; 16A; 25A; 31.5A; 40A; 50A; 63A
80A; 100A; 125A; 160A; 200A; 250A; 320A; 400A; 500A; 630A; 800A
1000A; 1600A; 2000A; 2500A; 4000A; 5000A; 6300A

Switches up to 63A can be installed in apartment panels and floor panels.
The following chain of amperages (80 - 800 amperes) is typical for switches used in industry in input distribution devices.
Next come the amperages of circuit breakers (over 1000A), which are installed in front of large industrial facilities; they often have selectivity (input circuit breakers).

3. According to the medium in which the shutdown occurs: air, vacuum, gas.
All circuit breakers of the BA series are air operated

4. By the number of poles: single-pole, two-pole, three-pole and four-pole.

5. According to the presence of current limitation: current-limiting and non-current-limiting.
Current-limiting circuit breakers (also non-selective) are:
— fast-acting (response time does not exceed 0.005 s);
— normal (switch-off time in the range from 0.02 to 0.1 s).
Non-current-limiting circuit breakers (also selective) allow you to adjust the time before the contacts disengage (no more than 1 second).

6. By types of releases: with maximum current release (MCR), with independent release (NR), with minimum voltage release (MRN) and with zero voltage release (NVR).

7. By type of drive: with a manual drive, with a motor (electromagnetic) drive, with a spring drive.

8. By installation method: stationary, retractable, plug-in.

9. According to the degree of protection from water (moisture, suspended water dust) and solid objects (tools, fingers, probes, nails, etc.) provided by the shell (circuit breaker housing) according to GOST 14254-96.

Design (principle of operation) of a circuit breaker

The circuit breaker is assembled from several components: the machine body, switching device, control mechanism, arc chutes, overcurrent releases and additional assembly units (shunt release, auxiliary contacts, undervoltage release, zero voltage release).
The body of the machine is made of dielectric material and guarantees a specified degree of protection from atmospheric influences and contact with live or mechanical parts of solid foreign bodies.
The switching device consists of moving and fixed contacts that engage (switch operation) and disengage (automatic or manual shutdown). A circuit breaker pole is made up of a pair of contacts, the number of poles can vary from one to four, and an arc chute is mounted in each pole.
Nowadays, contacts at the adhesion point are often made of silver-based cermets. The use of silver is due to its high electrical conductivity and lack of oxidation under normal conditions.
The control mechanism is an independent manual drive, which guarantees instant closing and opening of the main contacts. The control element is a handle or button.
The arc chute must ensure arc extinguishing under various network modes.
There are two types of arc extinguishing devices used in circuit breakers: semi-closed and open.
In the semi-closed version, the machine is closed with a casing in which slots are made to allow hot gases to escape. The emission zone of ionized gases reaches a length of only a few centimeters from the outlet openings. This solution is used for low-voltage equipment that is mounted with other devices, in distribution boards, and at manual circuit breakers.
At currents of 100 kA and above, open-type chambers with a large emission zone are used.
In circuit breakers, a deionic arc-extinguishing grid consisting of metal plates is widely used. In AC circuits with voltages up to 690 V, such devices are capable of extinguishing an arc with a current of up to 50 kA. In DC circuits with voltages up to 440 V, arc chutes made of steel plates successfully extinguish arcs with currents up to 55 kA. Extinguishing the arc occurs quite calmly with minimal release of heated ionized gases.
Overcurrent releases (MRT). A circuit breaker often uses a combined release - electromagnetic (instantaneous) and thermal releases.
The principle of operation of an electromagnetic release is that a load current is supplied to a coil with a winding made of copper wire. During normal operation, the current does not cause the core to move; but when short-circuit currents are high, the core is pulled or pushed out of the coil and acts on the tripping mechanism.
The thermal release is a bimetallic plate, which is made of two pressed metals with different linear expansions. When current is passed through the plate, it heats up and bends. When an overload occurs (currents exceeding the nominal value by 1.1 times or higher), the plate heats up sufficiently and acts on the release mechanism. The heating process can last from several minutes to an hour - the time after which the contacts open.

Manufacturers (factories) of circuit breakers
A few examples:

• "Kursk Electrical Equipment Plant" TM "KEAZ" (Kursk, Russia);
• company "IEK" (InterEnergoKomplekt in the past);
• electrical engineering company "EKF electrotechnica";
• Ulyanovsk plant of low-voltage equipment "Kontactor",
• "Divnogorsk plant of low-voltage circuit breakers" (TM "DZNVA"),
• international corporation "General Electric" (General Electric, a division of GE Consumer & Industrial Power Protection).