Circuit breakers are devices whose task is to protect an electrical line from exposure to powerful current that can cause overheating of the cable with further melting of the insulating layer and fire. An increase in current strength can be caused by too much load, which occurs when the total power of the devices exceeds the value that the cable can withstand in its cross-section - in this case, the machine does not turn off immediately, but after the wire heats up to a certain level. During a short circuit, the current increases many times over within a fraction of a second, and the device immediately reacts to it, instantly stopping the supply of electricity to the circuit. In this material we will tell you what types of circuit breakers are and their characteristics.

Automatic safety switches: classification and differences

In addition to residual current devices, which are not used individually, there are 3 types of network circuit breakers. They work with loads of different sizes and differ in their design. These include:

• Modular AV. These devices are installed in household networks in which negligible currents flow. Typically have 1 or 2 poles and a width that is a multiple of 1.75 cm.

• Molded switches. They are designed to operate in industrial networks with currents up to 1 kA. They are made in a cast case, which is why they got their name.
• Air electric machines. These devices can have 3 or 4 poles and can handle currents up to 6.3 kA. Used in electrical circuits with high power installations.

There is another type of circuit breaker for protecting the electrical network - differential. We do not consider them separately, since such devices are ordinary circuit breakers that include an RCD.

Types of releases

Releases are the main operating components of the automatic circuit breaker. Their task is to break the circuit when the permissible current value is exceeded, thereby stopping the supply of electricity to it. There are two main types of these devices, differing from each other in the principle of tripping:

• Electromagnetic.
• Thermal.

Electromagnetic type releases provide almost instantaneous operation circuit breaker and de-energizing a section of the circuit when a short circuit overcurrent occurs in it.

They are a coil (solenoid) with a core that is drawn inward under the influence of a large current and causes the tripping element to operate.

The main part of the thermal release is a bimetallic plate. When a current exceeding the rated value of the protective device passes through the circuit breaker, the plate begins to heat up and, bending to the side, touches the disconnecting element, which trips and de-energizes the circuit. The time it takes for the thermal release to operate depends on the magnitude of the overload current passing through the plate.

Some modern devices are equipped as an addition with minimum (zero) releases. They perform the function of turning off the AV when the voltage drops below limit value, corresponding to the technical data of the device. There are also remote releases, with the help of which you can not only turn off, but also turn on the AV, without even going to the distribution board.

The presence of these options significantly increases the cost of the device.

Number of poles

As already mentioned, the circuit breaker has poles - from one to four.

Selecting a device for a circuit based on their number is not at all difficult; you just need to know where they are used Various types AB:

• Single-pole circuits are installed to protect lines that include sockets and lighting. They are mounted on the phase wire without touching the neutral wire.
• The two-terminal network must be included in the circuit to which it is connected Appliances with sufficiently high power (boilers, washing machines, electric stoves).
• Three-terminal networks are installed in semi-industrial networks, to which devices such as borehole pumps or auto repair shop equipment.
• Four-pole AVs allow you to protect electrical wiring with four cables from short circuits and overloads.

The use of machines of different polarities is shown in the following video:

Characteristics of circuit breakers

There is another classification of machines - according to their characteristics. This indicator indicates the degree of sensitivity of the protective device to exceeding the rated current. The corresponding marking will show how quickly the device will react in the event of an increase in current. Some types of AVs work instantly, while others will take some time.

There is the following marking of devices according to their sensitivity:

• A. Switches of this type are the most sensitive and react instantly to increased load. They are practically not installed in household networks, using them to protect circuits that include high-precision equipment.
• B. These machines operate when the current increases with a slight delay. They are usually included in lines with expensive household appliances (LCD TVs, computers and others).
• C. Such devices are the most common in household networks. They are turned off not immediately after increasing the current strength, but after some time, which makes it possible to normalize it with a slight difference.
• D. The sensitivity of these devices to increasing current is the lowest of all types listed. They are most often installed in shields at the line approach to the building. They provide security for apartment automatic machines, and if for some reason they do not work, they turn off the general network.

Features of the selection of machines

Some people think that the most reliable circuit breaker is the one that can handle the most current, and therefore can provide the most protection to the circuit. Based on this logic, you can connect a machine to any network air type, and all problems will be solved. However, this is not at all true.

To protect circuits with different parameters, it is necessary to install devices with the appropriate capabilities.

Errors in the selection of AB are fraught with unpleasant consequences. If you connect a high-power protective device to a regular household circuit, it will not de-energize the circuit, even when the current significantly exceeds what the cable can withstand. The insulating layer will heat up and then begin to melt, but no shutdown will occur. The fact is that the current strength destructive to the cable will not exceed the AB rating, and the device will “consider” that there was no emergency. Only when the melted insulation causes a short circuit will the machine turn off, but by then a fire may already have started.

We present a table that shows the ratings of machines for various electrical networks.

If the device is designed for less power than what the line can withstand and which the connected devices have, the circuit will not be able to operate normally. When you turn on the equipment, the AV will constantly knock out, and ultimately, under the influence of high currents, it will fail due to “stuck” contacts.

Visually about the types of circuit breakers in the video:

Conclusion

The circuit breaker, the characteristics and types of which we discussed in this article, is a very important device that protects the electrical line from damage by powerful currents. The operation of networks not protected by automatic circuit breakers is prohibited by the Electrical Installation Rules. The most important thing is to choose the right type of AV that is suitable for a specific network.

An electrical network is a system that includes inputs, wires, current consumers, as well as switching equipment. Installation of circuit breakers provides protection for the network as a whole and individual consumers in emergency situations when the current parameters go beyond normal values ​​(short circuit, voltage surges, change in current direction, etc.). In addition, they allow, if necessary, infrequent switching of consumers remotely or manually (6-30 on/off cycles per day).

Electrical equipment care

Evolution and fundamental design of circuit breakers

The history of electrical equipment began long before the advent of the first commercial electrical networks. Thus, the principle of operation of a circuit breaker was discovered back in 1836 by the American scientist C. G. Page, but modern design was patented only in 1924 by the Swiss company Brown, Boveri & Cie. Since then, each machine has included the following elements:

• contact block;
• arc neutralization (quenching) chamber;
• release of the following types: thermal, electromagnetic, electronic, microprocessor;
• control mechanism: manual, spring or driven;
• free release mechanism.

Currently, a lot of electrical equipment is being produced, as illustrated by characteristics of circuit breakers, which provide reliable switching and protection of electrical networks and consumers of any complexity and power under any operating conditions. Number of models of these devices different manufacturers incalculable.

The Skat Technology catalogs present products from leading companies Siemens, Andeli, Schneider, whose products rightfully occupy leading positions in the electrical engineering market. Here you can see circuit breakers in the photo, as well as familiarize yourself with their main characteristics and installation methods. If you are not a professional in electrical engineering, we recommend using the help of our specialists, which can also be obtained online.

For those who are interested in how a circuit breaker works, we will give a short explanation. Each device has settings for certain parameters of current and conductor heating. These settings are provided by the current sensitivity of the release solenoid and the screw-adjustable thermal relay (calibration). If during network operation the parameters go beyond the established limits, the circuit breaks and consumers are de-energized.

Classification of circuit breakers

To classify electrical devices, there are regulatory documents that set out the technical and operational requirements for them. Classes of circuit breakers domestic and foreign production are determined in accordance with the following documents:

• GOST 9098-78;
• GOST 14255-69;
• GOST R 50345-2010;
• GOST R 50030.2-99;
• IEC 60898-95;
• EN 60947-2;
• EN 60898.

In accordance with domestic regulatory and technical documents, the classification of machines is carried out according to 12 parameters, which take into account dozens performance characteristics devices. The quantitative and qualitative values ​​of these parameters determine the purpose of the circuit breaker and the permissible conditions of its operation.

Basic classification parameters of circuit breakers

The higher the level of power grid architecture, the more difficult it is to select protection and control equipment for it, since it is necessary to take into account a large number of various parameters work. To achieve the desired result it is necessary to carry out engineering calculations all parameters so that the selection of circuit breakers and other electrical devices ensures reliable and safe work networks. The list of the main characteristics of the machines is as follows:

• rated currents of the main circuit and releases are respectively 6.3-6300 (22 ratings in total) and 15-3200 amperes (12 ratings in total);
• design - air or ASV (800-6300 A), in a molded case or MSSV (10-2500 A), modular or MSV (0.5-125 A) circuit breakers;
• number of poles of the main circuit – from one to four;
• presence or absence of current limitations;
• types of releases: zero, minimum, independent, maximum;
• presence or absence of contacts for connecting secondary circuits;
• I/O connection method: front, rear, combined, universal;
• mounting method: stationary, withdrawable (on DIN rail), on connectors;
• cut-off type: normal, selective, instantaneous;
• type of drive: manual, spring, with a propulsion device (electromagnet, pneumatic, etc.);
• normal or protected execution.

The listed characteristics have their own designation or quantitative expression. For example, the tripping curve of a circuit breaker is a graphical reflection of the tripping of the tripping release. It indicates at what value exceeding the rated current “In” the device is triggered. According to this parameter, foreign-made products are divided into 6 groups (types):

• A – 2-3 In;
• B – 3-5 In;
• C – 5-10 In;
• D – 10-20 In;
• Z – 2-4 In;
• K – 8-14 In.

Trip class of circuit breakers domestic production denoted by the letters B, C and D, since our industry does not produce other types of products. In turn, according to the cut-off speed, automatic machines are divided into normal (0.02-1 sec.) and high-speed or instantaneous (less than 0.005 seconds). Selectivity of circuit breakers means the ability to set different cut-off times with a delay of 0.25-0.6 seconds for subordinate electrical devices.

Automatic machines of this type have a main and additional operating circuit, which allows you to turn off the emergency section of the electrical network controlled by a slave device and maintain the current supply to the remaining consumers. The time range of performance and selection processes also reflects circuit breaker curves. Protection devices are triggered not only by current, but also by heating of the wires, which is provided by a thermal relay. Simply put, the electromagnetic release responds to current consumption, and the thermal relay responds to heating of the wiring.

The time-current characteristic of the circuit breaker depends on the setting of the latter. The thermal load should not exceed the rated value for wires of a certain cross-section by more than 1.45 times. It is determined taking into account the method of laying wires and the total load. Depending on the setting, the thermal relay can operate instantly or keep the network operational for a certain time, but not more than an hour.

On the importance of timely operation of protection equipment

From the above data it is clear how important the tripping time of the circuit breaker is. The minimum value of this indicator is necessary for powerful industrial equipment. Class D devices with instant release are usually used here. For household needs, class C automatic circuit breakers with normal release are sufficient.

The exception is worn-out networks and particularly sensitive current consumers, where devices of classes A and B should be used, in which the minimum response time of the circuit breaker during a short circuit not only provides protection, but also prevents fire of the wiring. By the way, the condition of the latter is often of decisive importance when choosing electrical equipment. If the wire size does not match the load on the network, the thermal characteristic of the circuit breaker will prevent its normal operation.

Reflection of the characteristics of electrical equipment in its markings

It is typical for electrical products to use the most important performance characteristics in product labeling. For lighting lamps, this is power consumption and luminous flux. Marking of circuit breakers much more complicated; a minimum of information can be squeezed into the product name. This is usually nominal operating voltage. Therefore, marking symbols are applied to the machine body:

• The current limit class is indicated by a number placed inside the square; the number of poles is indicated by a pictogram;
• the class or category of application of circuit breakers is displayed along with the rated current value - for example, “C16”;
• the maximum permissible operating current value, at which the risk of damage to the machine is eliminated, is indicated in a rectangular frame.

The information listed in the product labeling is enough for a specialist to decide how to select/select a circuit breaker in full accordance with the parameters of the electrical network. However, when purchasing a device yourself, it is easy to make a mistake if you do not take into account the wiring characteristics and the magnitude of the loads. For example, the operating parameters of open and closed wiring, copper and aluminum wires differ significantly.

If you are wondering how to choose/select a circuit breaker based on power, you should consider that copper wire cross-section 4 mm, laid open method, can withstand a load of 9 kW. The same wire, when the wiring is closed, will withstand 5.9 kW. It is clear that the power of the current consumer should not exceed the capacity of the wiring.

Likewise circuit breaker ratings must be less than the corresponding network parameters. Otherwise, there is a risk of overloading the electrical network, up to a wiring fire, to which the machine simply will not react. In order to avoid similar situation, are necessary preliminary calculations, which will ensure a balance between current consumers, wiring and protection and control equipment. For those who are interested in the question, how to choose a circuit breaker for your home, we’ll give you some advice: choose the rating of the device based on the wiring capacity (the cross-section and material of the wires, as well as the method of laying them).

Basic rules for connecting a circuit breaker

Proper design of electrical network architecture allows one to increase their reliability by an order of magnitude. Currently, we use a lot of household appliances and equipment, including those with significant power. The old Soviet-style wiring was not designed for such loads, so consumers often face the question of how to calculate the circuit breaker current to ensure safe operation of the home electrical network.

Based on its work experience, the Skat Technology company concluded that if there is a significant increase in the load on the network (for example, installing an electric stove), you should not use old wiring. It won't help either right choice circuit breaker for load current, since the wiring is not designed for it. It is best to completely reconstruct or replace the network with the distribution of current consumers into groups.

Electrical engineering is an exact applied science, therefore the production of electrical goods is carried out according to certain standards. This is clearly seen in the example of what types of circuit breakers there are, the design of which is designed for specific operating conditions. Dividing consumers into groups has long been practiced in industrial networks. On household level this approach looks like this:

• for lighting fixtures, the rating of the machine should not exceed 10 A;
• for regular sockets – 16 A;
• For power sockets for electric stoves, boilers and other things, a circuit breaker is selected according to the power of the consumers.

To implement this approach to network design, manufacturers offer a sufficient selection of machines with different quantities poles, differential type and other units. For domestic purposes, you should use devices in molded cases, in which all live parts are protected, which prevents accidental electric shock. In order to install a universal circuit breaker, you need distribution devices(cabinets, assemblies, etc.).

The variety of electrical devices is also explained by the fact that their design provides for various installation conditions. In other words, a device with identical parameters may have several versions. That's why circuit breaker connection diagram is a mandatory attachment to each product. It indicates the number of poles, phase and neutral connection points, methods of preparing wires for connection and other features of a particular model.

If a person has a minimal understanding of electrical engineering, he will not think long about how to connect a single-phase circuit breaker on the panel of his apartment. Just look at the diagram, there is nothing complicated about it. The only warning: if you change a machine, under no circumstances install a switch with a higher power than the previous one. First you need to make sure that the wiring can withstand the increased load.

Electrical equipment care

Electrical equipment, like any other devices, needs care. Maintenance of circuit breakers is carried out according to a certain procedure with strict frequency. Users are often unaware of this need, but it exists. Electrical equipment is subject to wear and tear; oxidation of contacts, aging of insulation, wear of moving parts and other changes gradually occur. Therefore, the power calculation of a circuit breaker made 5 years ago may not correspond to the real state of affairs.

Probably, many of you have experienced situations when a flawlessly working network begins to act up. An obvious manifestation of this is when a circuit breaker frequently trips for no apparent reason. The reason may be in the device itself, but most often this happens due to problems with wiring and hidden defects in the electrical circuits of household appliances and equipment.

To identify and prevent such situations, there is loading circuit breakers. It is carried out every three years using special equipment and is carried out to check whether the actual condition of the machine meets the requirements for the safe operation of electrical networks. The method for checking circuit breakers involves checking the insulation condition, the response time of overcurrent and heating protection, the condition of contacts and other parameters.

Conducting regular Maintenance ensures that problems are identified at an early stage, prevents more serious consequences and guarantees the safe operation of networks for the foreseeable future. Detected malfunctions of circuit breakers are eliminated if possible, but most often in such cases it is required complete replacement electrical devices, especially in the case of their small sizes.

Manufacturers of electrical products produce many spare parts for powerful industrial machines. For household or low-power equipment, only spare contact groups are usually produced. That's why replacement of circuit breakers- a typical action when repairing electrical networks. Regular maintenance of electrical equipment is not a burdensome procedure at all, including in terms of money. Its main goal is prevention.

The technical characteristics of the machines also include the guaranteed number of on/off cycles. According to these indicators, circuit breakers have a service life measured in decades, provided that the devices are properly installed and maintained in a timely manner. They must fully comply with the network parameters. In addition, to extend their service life, you should not use faulty electrical appliances that cause frequent power outages.

Professional services from the company "Scat Technology"

Our company specializes in work on engineering communications, including electrical networks. Our specialists are ready to give recommendations on the selection of circuit breakers and carry out network design, including load calculations and their distribution, taking into account all standards of safe operation. Experienced engineers will answer any practical questions, including how to connect a circuit breaker for different categories of current consumers, taking into account installation conditions, wiring condition and other factors.

Our catalogs include wide choose electrical products from leading manufacturers. Our range will allow you to carry out a complete set of works on the arrangement of electrical networks without much difficulty. If you are confused cost of circuit breakers with logos of famous brands, we remind you that high-quality products cannot be downright cheap. In addition, the service life of such electrical equipment is an order of magnitude higher than that of products of dubious origin.

Those who are wondering which circuit breakers are better should decide what meaning you put into it. For us, the determining factor is reliability and safety at adequate costs? We offer electrical products at the fairest prices, so we are confident that our customers do not overpay. Dimensions of circuit breakers are not always equivalent to prices, therefore, if you want to get a normal result in the arrangement of the electrical network, use the services of Skat Technology professionals.

In this article we will look at the main characteristics of circuit breakers that you need to know in order to correctly navigate when choosing them - these are rated current and time current characteristics of circuit breakers.

Let me remind you that this publication is part of a series of articles and videos devoted to electrical protection devices from the course

The main characteristics of the circuit breaker are indicated on its body, where it is also marked trademark or manufacturer's brand and catalog or serial number.

The most main characteristic circuit breaker - rated current. This is the maximum current (in Amperes) that can flow through the circuit breaker indefinitely without disconnecting the protected circuit. When the flowing current exceeds this value, the machine is triggered and opens the protected circuit.

A number of rated current values ​​of circuit breakers are standardized and are:

6, 10, 16, 20, 25, 32, 40, 50, 63, 80, 100A.

The rated current of the machine is indicated on its body in amperes and corresponds to the temperature environment+30˚С. As the temperature increases, the rated current decreases.

When some consumers, for example, refrigerators, vacuum cleaners, compressors, etc., are connected to the electrical network, inrush currents briefly arise in the circuit, which can be several times higher than the rated current of the machine. For a cable, such short-term surges of current are not dangerous.

Therefore, so that the machine does not turn off every time with a small short-term increase in the current in the circuit, machines with different types of time-current characteristics are used.

Thus, the following main characteristic:

time-current characteristic of circuit breaker operation- this is the dependence of the shutdown time of the protected circuit on the strength of the current flowing through it. The current is indicated as a ratio to the rated current I/Inom, i.e. how many times the current flowing through the circuit breaker exceeds the rated current for a given circuit breaker.

The importance of this characteristic lies in the fact that machines with the same will turn off differently (depending on the type of time-current characteristic). This makes it possible to reduce the number of false alarms by using circuit breakers with different current characteristics for different types loads,

Let's consider the types of time-current characteristics:

— Type A(2-3 rated current values) are used to protect circuits with long electrical wiring and to protect semiconductor devices.

— Type B(3-5 rated current values) are used to protect circuits with a low inrush current multiplicity with a predominantly active load (incandescent lamps, heaters, furnaces, lighting electrical networks general purpose). Indicated for use in apartments and residential buildings, where the loads are mainly active.

— Type C(5-10 rated current values) are used to protect circuits of installations with moderate starting currents— air conditioners, refrigerators, home and office socket groups, gas discharge lamps with increased starting current.

— Type D(10-20 rated current values) are used to protect circuits supplying electrical installations with high starting currents (compressors, lifting mechanisms, pumps, machines). They are installed mainly in industrial premises.

— Type K(8-12 rated current values) are used to protect circuits with inductive loads.

— Type Z(2.5-3.5 rated current values) are used to protect circuits with electronic devices sensitive to overcurrents.

In everyday life they are usually used with the characteristics B,C and very rarely D. The type of characteristic is indicated on the body of the machine with a Latin letter in front of the rated current value.

The marking “C16” on the circuit breaker will indicate that it has an instantaneous trip type C (that is, it trips at a current value of 5 to 10 values ​​​​of the rated current) and a rated current of 16 A.

The time-current characteristic of a circuit breaker is usually given in the form of a graph. The horizontal axis indicates the multiple of the rated current value, and along vertical axis— time of operation of the machine.

The wide range of values ​​on the graph is due to the spread of parameters of circuit breakers, which depend on temperature - both external and internal, since the circuit breaker is heated by the electric current passing through it, especially in emergency modes - by overload current or short circuit current (SC).

The graph shows that with a value of I/In≤1, the circuit breaker shutdown time tends to infinity. In other words, as long as the current flowing through the circuit breaker is less than or equal to the rated current, the circuit breaker will not trip (trip).

The graph also shows that what more value I/Iн (i.e., the more current flowing through the circuit breaker exceeds the rated current), the faster the circuit breaker will turn off.

When a current flows through the circuit breaker, the value of which is equal to the lower limit of the operating range of the electromagnetic release (3In for “B”, 5In for “C” and 10In for “D”), it must turn off in a time of more than 0.1 s.

When a current flows equal to the upper limit of the operating range of the electromagnetic release (5In for “B”, 10In for “C” and 20In for “D”), the circuit breaker will turn off in less than 0.1s. If the main circuit current is within the instantaneous trip current range, the circuit breaker trips with either little or no time delay (less than 0.1 s).

Hello friends. The topic of the post is the types and types of circuit breakers (automatic circuit breakers, AB). I also want the results of the crossword puzzle tournament.

Types of machines:

Can be divided into AC switches, direct current and universal, operating at any current.

Design - there are air, modular, in a molded case.

Rated current indicator. The minimum operating current of a modular machine is 0.5 Amperes, for example. Soon I will write about how to choose the right rated current for a circuit breaker, subscribe to the blog news so as not to miss it.

Voltage rating is another difference. In most cases, AVs operate in networks with a voltage of 220 or 380 Volts.

There are current-limiting and non-current-limiting.

All switch models are classified by the number of poles. They are divided into single-pole, double-pole, three-pole and four-pole circuit breakers.

Types of releases - maximum current release, independent release, minimum or zero voltage release.

Speed ​​of operation of circuit breakers. There are high-speed, normal and selective automatic machines. They are available with or without a time delay, independent or inversely dependent on the current response time delay. Characteristics can be combined.

They differ in the degree of protection from the environment - IP, mechanical influences, conductivity of the material. By type of drive - manual, motor, spring.

By the presence of free contacts and the method of connecting conductors.

Types of machines:

What does type AB mean?

Automatic circuit breakers contain two types of circuit breakers - thermal and magnetic.

Magnetic quick release switch designed to protect against short circuit. The tripping of the circuit breaker can occur in a time from 0.005 to several seconds.

The thermal breaker is much slower, designed to protect against overload. It works using a bimetallic plate that heats up when the circuit is overloaded. Response time ranges from a few seconds to minutes.

The combined response characteristic depends on the type of connected load.

There are several types of AV shutdown. They are also called types of time-current shutdown characteristics.

A, B, C, D, K, Z.

A– used for breaking circuits with long electrical wiring, serves as good protection for semiconductor devices. They operate at 2-3 rated currents.

B- For lighting network general purpose. They operate at 3-5 rated currents.

C– lighting circuits, electrical installations with moderate starting currents. These can be motors, transformers. The overload capacity of the magnetic circuit breaker is higher than that of type B switches. They operate at 5-10 rated currents.

D– used in circuits with active-inductive loads. For electric motors with high starting currents, for example. At 10-20 rated currents.

K– inductive loads.

Z– for electronic devices.

It is better to look at the data on the operation of switches of types K, Z in the tables specifically for each manufacturer.

That seems to be all, if there is anything to add, leave a comment.

The circuit breaker is electrical device, the main purpose of which is to switch its operating state when a certain situation arises. Electrical circuit breakers combine two devices: a regular switch and a magnetic (or thermal) release, the task of which is to timely break the electrical circuit if the threshold current value is exceeded. Circuit breakers, like all electrical devices, also have different varieties, which divides them into certain types. Let's take a look at the main classifications of circuit breakers.

1" Classification of machines by number of poles:

A) single-pole circuit breakers

b) single-pole circuit breakers with neutral

c) two-pole circuit breakers

d) three-pole machines

e) three-pole circuit breakers with neutral

e) four-pole machines

2" Classification of automatic machines according to the type of releases.

The design of various types of circuit breakers usually includes 2 main types of releases (breakers) - electromagnetic and thermal. Magnetic circuit breakers are used for electrical protection against short circuits, while thermal circuit breakers are intended mainly to protect electrical circuits against a certain overload current.

3" Classification of automatic machines according to tripping current: B, C, D, (A, K, Z)

GOST R 50345-99, according to instantaneous tripping current, automatic machines are divided into the following types:

A) type “B” - over 3 In to 5 In inclusive (In is the rated current)

b) type “C” - over 5 In up to 10 In inclusive

B) type “D” - over 10 In to 20 In inclusive

Machine manufacturers in Europe have a slightly different classification. For example, they have additional type"A" (over 2 In to 3 In). Some manufacturers of circuit breakers also have additional switching curves (ABB has circuit breakers with K and Z curves).

4" Classification of machines according to the type of current in the circuit: constant, variable, both.

Rated electric currents for the main circuits of the release are selected from: 6.3; 10; 16; 20; 25; 32; 40; 63; 100; 160; 250; 400; 630; 1000; 1600; 2500; 4000; 6300 A. Automatic machines are also additionally produced with rated currents of the main electrical circuits of the automatic machines: 1500; 3000; 3200 A.

5" Classification according to the presence of current limitation:

a) current-limiting

b) non-current limiting

6" Classification of automatic machines by types of releases:

A) with overcurrent release

b) with independent release

c) with minimum or zero voltage release

7" Classification of machines according to time delay characteristics:

A) without time delay

b) with a time delay independent of current

c) with a time delay inversely dependent on the current

d) with a combination of the specified characteristics

8" Classification according to the presence of free contacts: with and without contacts.

9" Classification of machines according to the method of connecting external wires:

A) with rear connection

b) with front connection

c) with combined connection

d) with universal connection (both front and rear).

10" Classification by type of drive: with manual, motor and spring.

P.S. Everything has its own varieties. After all, if there was only one thing in its only copy, it would be, at a minimum, simply boring and too limited! The good thing about the variety is that you can choose exactly what best suits your needs.

Any circuit breaker has an important component of the device: a release, which serves to open or close the switching device. Essentially, the release opens the contacts of the circuit breaker when overcurrents occur and the voltage decreases. GOST R 50030.1 (5) defines the concept of a release as “A device mechanically connected to a contact switching device, which releases the holding devices and thereby allows the opening or closing of the switching device.” Standard IEC 61992‑1 (6) complements this definition of a circuit breaker release - the release may consist of mechanical, electronic or electromagnetic components; refers to any device with a mechanical action that is used for tripping operation when certain conditions are encountered in the input circuit; a machine may have several releases.

Types of releases

The following types of releases are most often found in household circuit breakers: thermal, electronic and electromagnetic. They quickly recognize a critical situation (the appearance of overcurrents, overloads and voltage surges) and open the circuit breaker contacts, preventing damage to electrical equipment and protecting the wiring. In addition to these types, there are also zero-voltage, minimum-voltage, independent, semiconductor, and mechanical releases.

Overcurrents - an increase in current in the electrical network exceeding the rated current of the machine. These are overload and short circuit currents.

Overload current - overcurrent in a functional network.

Short circuit current is an overcurrent resulting from the short circuit of two network components with extremely low resistance between these elements.

Thermal release

The thermal release opens the contacts of the circuit breaker when the rated current is slightly exceeded and is characterized by an increased response time. In case of short-term excesses of the current load, it does not operate; this is convenient in networks where short-term excesses of the rated current of the machine are frequent.

The thermal release is a bimetallic strip, one end of which is located next to the release trigger. If the current increases, the plate begins to bend and approach the trigger mechanism, touches the bar, and it, in turn, opens the contacts of the circuit breaker. The operating principle is based on the physical properties of metal, which expands when heated, which is why such a release is called thermal.

The advantages of a thermal release include the absence of surfaces rubbing against each other, resistance to vibration, and low cost due to its simple design. But you also need to pay attention to the disadvantages - the operation of a thermal release is highly dependent on the ambient temperature, they should be placed in places with a stable temperature, away from heat sources, otherwise numerous false alarms are possible.

Electronic release

The electronic release includes measuring devices (current sensors), a control unit and an actuating electromagnet. Electronic releases are designed to issue a command to automatically turn off the machine with a given program when an overcurrent or short circuit occurs in the electrical circuit. When the current through the circuit breaker is exceeded, the electronic release unit begins counting the response time in accordance with the time-current characteristic. If during the actuation time the current decreases to a value below the threshold, then automatic operation will not occur.

The advantages of electronic releases include: a wide range of settings, strict adherence of the device to a given program, and the presence of indicators. The main disadvantage is the rather high cost, as well as the sensitivity of the release to the effects of electromagnetic radiation.

Electromagnetic release

The electromagnetic release (cut-off) operates instantly, preventing the slightest possibility of damage to the components of the electrical circuit. This is a solenoid with a movable core that acts on the tripping mechanism. As current flows through the solenoid winding, if the current load is exceeded, the core is retracted under the influence of the electromagnetic field.

The electromagnetic release is triggered when the short circuit current is exceeded. It has sufficient strength, is resistant to vibration, but creates a magnetic field.

Circuit breaker release current

The current of the circuit breaker release has a specific value (nominal), meaning the amount of current at which the circuit breaker will open the circuit. The current in the thermal release is always equal to or less than the rated current of the circuit breaker. Whenever the current load on the release is exceeded, the machine will shut down. In this case, the time after which the contacts open depends on the time of flow of the excess load current. The tripping time of the thermal release can be calculated using the time-current characteristics.

The current of the electromagnetic release switches off the circuit breaker instantly when the rated current of the circuit breaker is exceeded, most often this happens during a short circuit. Before a short circuit, the current in the network increases very quickly, which is taken into account by the electromagnetic release device, resulting in a very rapid impact on the release mechanism. The response speed in this case is a fraction of a second.

They can be equipped with the following releases built into them:

Electromagnetic or electronic overcurrent release of instantaneous or delayed action with a time delay practically independent of the current;

Electrothermal or electronic inertial overcurrent release with a current-dependent time delay;

Leakage current release;

Minimum voltage actuator;

Trip release reverse current or reverse power;

Independent release (remote switch off).

The first two types are installed in all three poles, the rest - one per switch. The set currents, as well as the time delays of the current releases, can be adjustable. One or more types of current releases and, in addition to them, an undervoltage release, an independent release and a switching electromagnet can be used in one circuit breaker.

In terms of response time, electromagnetic and similar electronic releases have four types:

Releases that ensure the operation of the circuit breaker in a time much less than 0.01 s, and the switching off of the short-circuit current before it reaches its impact value. Such AVs are called current-limiting.

Releases that provide disconnection of the short-circuit current during the first passage of the current through the zero value tc = 0.01 s.

Unregulated releases, the response time of which exceeds 0.01 s;

Releases with an adjustable time delay (0.1-0.7 s), which make it possible to achieve slow operation relative to other circuit breakers in the same network, are called selective.

Leakage current releases are used to quickly disconnect sections of the network in which, due to insulation failure or people touching the conductors, a leakage current to the ground has occurred. In this case, the release setting current is selected in the range from 10 to 30 mA, and the voltage dependence time is selected in the range from 10 to 100 ms. This protection is now considered more effective in protecting people from electric shock.

Minimum voltage releases are used to disconnect power sources when they stop supplying the network (early ATS)_, as well as to disconnect electrical receivers, the self-starting of which when the voltage is automatically restored is undesirable. The release voltage is selected in the range from 0.8 to 0.9 Un, the response time is in accordance with the requirements of automatic network power restoration systems.

Independent releases are used for local remote and automatic shutdown of circuit breakers when external protective devices are triggered.

Reverse current or reverse power releases are used to protect generators operating in the electrical system from synchronous failure.

17. Overcurrent directional protection (principle of operation, circuit diagram, calculation of time delays).

Directed current protection MTNZ lines

T 1 > t → 2 > t 3

I p = I` short I p = I` short

U p = U in U p = U in

φ p = 180 - φ a φ p = φ a t 4 > t ← 3 > t 2

I p = I`` short I p = I` short

U p = U in U p = U in

φ p = φ a φ p = 180 - φ a

Switches Q1 - Q3 have directional overcurrent protection. It differs from conventional MTZ in that an additional element is introduced that determines the direction of the short-circuit power - a power direction relay, which reacts to the phase of the short-circuit current relative to the voltage on the substation buses at the installation site of the protection kit, then the “-” power sign and the power direction relay blocks the set protection. If the direction of the short circuit power is from the busbars to the line, then this is the “+” sign of the short circuit power and the power direction relay, closing its contacts, allows the MTNZ set to operate.

As a result of the action of directional protection, sets 2 and 3 do not need to be coordinated, because they are decoupled using the directional action of a relay. This page violates copyright

In order for all equipment in your home or workplace to be protected from electrical surges, you need to install special circuit breakers. They will be able to detect a surge and quickly react to it by disconnecting the entire system from the electricity supply. A person cannot do this on his own, but an automatic certain type done in a few seconds.

Types of machines

Device sensitivity

Before you get acquainted with the types of machines, you need to find out with what sensitivity the devices are suitable for home use, and which ones will be inappropriate. This indicator will indicate how quickly the device will respond to a power surge. It has several markings:

Classification of machines

There are different types of machines in relation to the type of current, rated voltage or current indicator and other technical characteristics. Therefore, you need to specifically understand each point separately.

Current type

In relation to this characteristic, machines are divided into:

1. For operation on AC power;
2. For operation in a DC network;
3. Universal models.

Everything is clear here and no additional explanation is needed.

Based on rated current

The value of this characteristic will determine in the network what maximum value the circuit breaker can operate with. There are devices that can operate from 1 A to 100 A and more. The minimum value with which machines can be found on sale is 0.5 A.

Rated voltage indicator

This characteristic indicates what voltage this type of circuit breaker can operate with. Some can operate on a network with a voltage of 220 or 380 Volts - these are the most common options for domestic use. But there are machines that will cope well with higher rates.

By ability to limit the flow of electricity

According to this characteristic, the following are distinguished:

Other characteristics

The number of poles can be from one to four. Accordingly, they are called single-pole, double-pole, and so on.

Automatic machines by number of poles

By structure they are distinguished:

Based on the discharge speed, high-speed, normal and selective devices are produced. They can have a time delay function that can be inversely dependent on the current or independent of it. The time delay may not be set.

Automatic machines also have a drive, which can be manual, connected to a motor or a spring. Switches differ in the presence of free contacts and in the method of connecting conductors.

An important characteristic will be protection from environmental influences. Here we can highlight:

1. IP protection;
2. From mechanical impact;
3. Current conductivity of the material.

All characteristics can be combined in various combinations. It all depends on the model and manufacturer.

Switch types

The machine inside contains a release, which, using a lever, latch, spring or rocker, can instantly disconnect the network from the supply of electricity. Types of circuit breakers are distinguished by the type of release. There are:

Circuit breakers are much more cost effective than fuses. This is because after cooling, the machine can already be turned on, and it will work as it should if the cause of the overload is eliminated. The fuse needs to be replaced. It may not be available and replacing it may take a long time.

Hello friends. The topic of the post is the types and types of circuit breakers (automatic circuit breakers, AB). I also want the results of the crossword puzzle tournament.

Types of machines:

Can be divided into AC, DC and universal switches operating at any current.

Design - there are air, modular, in a molded case.

Rated current indicator. The minimum operating current of a modular machine is 0.5 Amperes, for example. Soon I will write about how to choose the right rated current for a circuit breaker, subscribe to the blog news so as not to miss it.

Voltage rating is another difference. In most cases, AVs operate in networks with a voltage of 220 or 380 Volts.

There are current-limiting and non-current-limiting.

All switch models are classified by the number of poles. They are divided into single-pole, double-pole, three-pole and four-pole circuit breakers.

Types of releases - maximum current release, independent release, minimum or zero voltage release.

Speed ​​of operation of circuit breakers. There are high-speed, normal and selective automatic machines. They are available with or without a time delay, independent or inversely dependent on the current response time delay. Characteristics can be combined.

They differ in the degree of protection from the environment - IP, mechanical influences, conductivity of the material. By type of drive - manual, motor, spring.

By the presence of free contacts and the method of connecting conductors.

Types of machines:

What does type AB mean?

Automatic circuit breakers contain two types of circuit breakers - thermal and magnetic.

Magnetic quick-release switch is designed for short-circuit protection. The tripping of the circuit breaker can occur in a time from 0.005 to several seconds.

The thermal breaker is much slower, designed to protect against overload. It works using a bimetallic plate that heats up when the circuit is overloaded. Response time ranges from a few seconds to minutes.

The combined response characteristic depends on the type of connected load.

There are several types of AV shutdown. They are also called types of time-current shutdown characteristics.

A, B, C, D, K, Z.

A– used for breaking circuits with long electrical wiring, serves as good protection for semiconductor devices. They operate at 2-3 rated currents.

B– for general purpose lighting network. They operate at 3-5 rated currents.

C– lighting circuits, electrical installations with moderate starting currents. These can be motors, transformers. The overload capacity of the magnetic circuit breaker is higher than that of type B switches. They operate at 5-10 rated currents.

D– used in circuits with active-inductive loads. For electric motors with high starting currents, for example. At 10-20 rated currents.

K– inductive loads.

Z– for electronic devices.

It is better to look at the data on the operation of switches of types K, Z in the tables specifically for each manufacturer.

That seems to be all, if there is anything to add, leave a comment.