What are three-phase machines. Electric machines

The topic of our today's article is the rating of manufacturers of automatic switches in the domestic and foreign markets. Next, we will tell you which company is better to give preference to when choosing a machine, and also provide readers of the site with leading brands that produce automation for domestic and industrial use. A brief overview of the best economy class AVs that are most often used in a house and apartment will also be provided.

Brand Overview

So, to begin with, we will briefly talk about the main manufacturers of circuit breakers. As for foreign brands, the most famous are:

• ABB. The Swedish-Swiss company, which is rightfully considered a leader in the production of electrical products. To date, ABB circuit breakers are the highest quality, durable and safe to use. As you understand, you will have to pay more money for such foreign products than for a domestic model. At the same time, the difference in price is small, therefore, for a house and an apartment, we recommend buying automatic machines from the manufacturer ABB.
  
• Legrand. Country of origin - France. Legrand circuit breakers are not inferior in quality to the ABB brand, therefore, for electrical work Legrand products are also preferred. In terms of cost, the machines are about the same, in fact, as in terms of reliability.
  
• Schneider Electric. Another French firm that closes the TOP-3 the best manufacturer specializing in the production of reliable circuit breakers. Schneider Electric has long settled in the Russian market of electrical products and has many positive reviews from experienced electricians.
  
• General Electric. An American manufacturer of power machines and other electrical products, which can also be called one of the best in quality. To date, there are many discussions on the forums about which is better: GE or Legrand. Here we can say that both brands produce good quality circuit breakers, but in fact, there is more demand for Legrand in the Russian market.
  
• Siemens. Siemens company specializes not only in the production of automation, but still has a wide range of models for industrial and domestic use. The quality is already a little worse than that of the top three, but still very high. The price is also slightly lower compared to manufacturers such as ABB, Legrand and Schneider Electric.
• Moeller. German firm, successfully competing with such a global giant as ABB. Despite the fact that in 2007 Moeller was bought out by the American Eaton Corporation, this did not affect the quality and reliability of the products for the worse. Moeller circuit breakers meet all international standards and are very popular.

Among domestic manufacturers of automatic machines, the best quality from brands such as:

I would also like to say a few words about products from China. Chinese circuit breakers EKF electrotechnica, whose direct competitors are IEK circuit breakers. Both companies have about the same price and similar quality. Oddly enough, China gives a guarantee on its product for a period of 5 years.

Our rating

So, we have listed all the most popular domestic and foreign companies that are engaged in the production of these devices. Now I would like to provide my own rating of manufacturers of circuit breakers for 2019:

1. ABB, in particular the S200 series. A detailed overview of ABB machines is available at the link:. Slightly inferior to SH200.
2. Legrand, TX3 or DX3 series.
3. Schneider Electric, Acti9 iC or iK series. More budget option Easy 9.
4. Siemens, 5SX, 5SY, 5SP, 5SL series.
5. General Electric, DMS LINE.
6. Moeller, PL6 or PL7.
7. Hager, MS series.
8. KEAZ, OptiDin BM63.
9. Eaton, xPole Home. By the way, we did a review of the machine of this series in a separate article:.
10. DEKraft, BA-103.

The only thing I would like to clarify is that this rating of manufacturers of electric machines is not entirely convenient, so that on its basis by company. Here, you must first decide how much money you can allocate for protective automation for your home. Even companies like ABB have their own series of low cost budget models. If you need to buy an economy-class machine, we recommend that you still give preference to reliability - the brands Legrand, ABB and Schneider Eletric. For supporters of Russian products, we can advise DEKraft, because. On the forums, we did not meet a lot of negative reviews about this company!

That's all I wanted to tell you about companies specializing in the production of protective automation. We hope you do right choice and use our rating of circuit breakers!

Related content:

It is easier and cheaper to prevent the fire-hazardous consequences of destruction than to complain bitterly about the measures not taken. Prevention of ignition of the electrical network consists in the installation of protective equipment. In the last century, the function of protecting against short circuits and against the danger of overload was entrusted to porcelain fuses with replaceable fuses, then to automatic plugs. However, due to a significant increase in the load on power lines, the situation has changed. It's time to replace outdated devices with reliable machines. In order for the choice of a circuit breaker to end with the acquisition of a device with the appropriate characteristics, information about a number of electrical nuances is required.

Why do we need automatics?

Circuit breakers are devices designed to protect the power cable, more precisely, its insulation from melting and integrity violations. Automatic machines do not protect the owners of equipment from shock and do not protect the equipment itself. For these purposes, an RCD is equipped. The task of the automata is to prevent overheating, which accompanies the flow of overcurrents to the entrusted section of the circuit. Thanks to their use, the insulation will not be melted and damaged, which means that the wiring will operate in normal mode without the threat of fire.

The operation of circuit breakers is to open the electrical circuit in the event of:

• the appearance of TKZ (further short-circuit currents);
• overload, i.e. passage through the protected section of the network of currents, the strength of which exceeds the permissible operational value, but is not a TKZ;
• a noticeable decrease or complete disappearance of tension.

The automata guard the section of the chain following them. In other words, they are set on the input. They protect the lines of lighting and sockets, the mains for connecting household equipment and electric motors in private homes. These lines are laid with a cable of various sections, because equipment of different capacities is powered by them. Therefore, to protect network sections with unequal parameters, protection devices with unequal capabilities are needed.

If you want to know how to install socket boxes, we advise you to read the article

It would seem that it is possible, without too much trouble, to purchase the most powerful automatic shutdown devices for installation on each of the lines. The step is fundamentally wrong! And the result of it will lay a direct "path" to the fire. Protection against the vagaries of electric current is a delicate matter. Therefore, it is better to learn how to choose a circuit breaker, and install an apparatus that breaks the circuit when a real need arises.

Attention. An oversized circuit breaker will carry currents that are critical to the wiring. It will not turn off the protected section of the circuit in a timely manner, due to which the cable insulation will melt or burn.

Automatic machines with underestimated characteristics will also present a lot of surprises. They will endlessly break the line when the equipment is started and eventually break due to repeated exposure to too large currents. Contacts are soldered, which is called "sticky".

The design and principle of operation of the machine

It will be difficult to make a choice without understanding the circuit breaker device. Let's see what is hidden in a miniature box made of refractory dielectric plastic.

Releases: their types and purpose

The main working bodies of automatic switches are releases that break the circuit in case of exceeding the standard operating parameters. The releases differ in the specifics of their action and in the range of currents to which they must respond. Their ranks include:

• electromagnetic releases, almost instantly responding to the occurrence of TKZ and "cutting off" the protected section of the network in hundredths or thousandths of a second. They consist of a coil with a spring and a core, which is drawn in by the action of overcurrents. Retracting, the core strains the spring, and it makes the release device work;
• thermal bimetal releases acting as an overload barrier. They undoubtedly also react to TKZ, but they are required to perform a slightly different function. The task of thermal counterparts is to break the network in the event that currents flow through it that exceed the maximum operating parameters of the cable. For example, if a 35A current flows through the wiring intended for transportation of 16A, the plate consisting of two metals will bend and cause the machine to turn off. Moreover, she will courageously “hold” 19A for more than an hour. But 23A will not be able to “endure” for an hour, it will work earlier;
• semiconductor releases are rarely used in household machines. However, they can serve as a working body of a protective switch at the input to a private house or on the line of a powerful electric motor. The measurement and fixation of the anomalous current in them is carried out by transformers, if the device is installed on the network alternating current, or choke amplifiers if the device is connected to a DC line. Disengagement is carried out by a block of solid-state relays.

There are also zero or minimum releases, most often used as an addition. They disconnect the network when the voltage drops to any limit value specified in the data sheet. A good option is remote releases that allow you to turn off and turn on the machine without opening the control cabinet, and locks that fix the “off” position. It is worth considering that equipping with these useful additions significantly affects the price of the device.

Automatic machines used in everyday life are most often equipped with a well-functioning combination of an electromagnetic and thermal release. Devices with one of these devices are much less common and used. Nevertheless, combined-type circuit breakers are more practical: two in one is more profitable in every sense.

Extremely important additions

There are no useless components in the design of the circuit breaker. All components work diligently in the name of a common safety cause, these are:

• an arcing device mounted on each pole of the machine, of which there are from one to four pieces. It is a chamber in which, by definition, the electric arc that occurs when the power contacts are forced to open is extinguished. Copper-plated steel plates are located in parallel in the chamber, dividing the arc into small parts. The fragmented threat to the fusible parts of the machine in the arc extinguishing system cools down and completely disappears. Combustion products are discharged through gas outlet channels. An addition is a spark arrestor;
• a system of contacts subdivided into fixed, built into the housing, and movable, pivotally attached to the semi-axes of the levers of the opening mechanisms;
• calibration screw, with which the thermal release is adjusted in the factory;
• a mechanism with a traditional inscription "on / off" with the corresponding function and with a handle intended for implementation;
• connection terminals and other devices for connection and installation.

Here is what the process of extinguishing the arc looks like:

Let's dwell a little on the power contacts. The fixed version is brazed with electromechanical silver optimizing the electrical durability of the switch. When an unscrupulous manufacturer uses a cheap silver alloy, the weight of the product decreases. Sometimes silver plated brass is used. “Substitutes” are lighter than standard metal, therefore a high-quality device of a reputable brand weighs somewhat more than the “left” counterpart. It is important to note that when replacing the silver soldering fixed contacts with cheap alloys, the resource of the machine is reduced. It will withstand less cycles of shutdown and subsequent inclusion.

Decide on the number of poles

It has already been mentioned that this protection device can have from 1 to 4 poles. Choosing the number of poles of the machine is as easy as shelling pears, because it all depends on its purpose of use:

• a single-pole machine will perfectly cope with the protection of lighting lines and sockets. Mounted only on the phase, no zeros!;
• a two-pole switch will protect the cable that feeds the electric stoves, washing machines and water heaters. If powerful household appliances not in the house, they put it on the line from the shield to the entrance to the apartment;
• a three-pole device is required for three-phase wiring equipment. This is already semi-industrial scale. In everyday life there may be a workshop line or well pump. A three-pole device must not be connected to a ground wire. He must always be in full combat readiness;
• four-pole circuit breakers are used to protect four-wire wiring from fire.

If it is planned to protect the wiring of an apartment, bath, house with the help of two-pole and single-pole circuit breakers, a two-pole device is installed first, then a single-pole device with a maximum rating, then in descending order. The principle of "ranking": from a more powerful component to a weak, but sensitive one.

Marking - information for reflection

We figured out the device and the principle of operation of the machines. Learned why. Now let's boldly proceed to the analysis of the markings affixed to each circuit breaker, regardless of the logo and country of origin.

The main reference point is the denomination

Because the purpose of acquiring and installing the machine is to protect the wiring, then first of all you need to focus on its characteristics. The current flowing through the wires heats the cable in proportion to the resistance of its current-carrying core. In short, the thicker the vein, the greater value current can pass through it without melting the insulation.

In accordance with the maximum value of the current transported by the cable, the rating of the automatic shutdown device is selected. You don’t need to calculate anything, the interdependent values ​​\u200b\u200bof electrical installation devices and wiring by caring electricians have long been summarized in the table:

Tabular information should be somewhat adjusted according to domestic realities. The prevailing number of household sockets is designed to connect a wire with a core of 2.5 mm², which, according to the table, implies the possibility of installing a machine with a rating of 25A. The real value of the outlet itself is only 16A, which means you need to buy a circuit breaker with a rating equal to the rating of the outlet.

A similar adjustment should be made if there is any doubt about the quality of the existing wiring. If there is a suspicion that the cable cross-section might not correspond to the size specified by the manufacturer, it is better to play it safe and take an automatic machine, the nominal value of which is one position less than the table indicator. For example: according to the table, an automatic machine for 18A is suitable for protecting the cable, but we will take it for 16A, because we bought the wire from Vasya on the market.

Calibrated characteristics of the nominal value of the device

This characteristic is the operating parameters of the thermal release or its semiconductor counterpart. It is a coefficient, by multiplying by which we get the current strength during overload, which the device may or may not hold for a certain period of time. The value of the calibrated characteristic is set during the production process, it is not subject to adjustment at home. Pick it up from the standard range.

The calibrated characteristic indicates how long and what kind of overload the machine can withstand without disconnecting the circuit section from the power supply. Usually these are two numbers:

• the smallest value indicates that the machine will pass current with parameters exceeding the standard for more than an hour. For example: a 25A machine will pass a current of 33A for more than an hour without disconnecting the protected section of the wiring;
• the largest value is the limit beyond which the shutdown will occur in less than an hour. The device specified in the example will quickly turn off at a current of 37 or more amperes.

If the wiring runs in a strobe formed in a wall with impressive insulation, the cable will practically not be cooled during overload and the accompanying overheating. So, in an hour, the wiring can be badly damaged. Maybe no one will immediately notice the result of the excess, but the service life of the wires will be significantly reduced. Therefore, for hidden wiring, we will look for a switch with minimal calibration characteristics. For the open version, you can not particularly dwell on this value.

Setpoint - indicator of instantaneous operation

This figure on the case is a characteristic of the operation of the electromagnetic release. It indicates the limiting value of the anomalous current strength, which, with repeated shutdowns, will not affect the performance of the device. It is normalized in units of current, and is indicated in numbers or Latin letters. With numbers, everything is extremely simple: this is the face value. But hidden meaning lettering is worth finding out.

Letters are affixed on machines made according to DIN standards. They denote the multiplicity of the maximum current that occurs when the equipment is turned on. A current that is several times higher than the operating characteristics of the circuit, but does not cause a shutdown and does not render the device unusable. It is simpler, how many times the switching current of the equipment can exceed the rating of the device and cable without threatening consequences.

For circuit breakers used in everyday life, these are:

• V- designation of automata capable of responding without their own damage to currents exceeding the nominal value in the range from 3 to 5 times. Very suitable for equipping old buildings and rural areas. They are not often used, therefore for the distribution network they are most often a custom item;
• WITH- designation of these protective equipment, the operating range of which is in the range from 5 to 10 times. The most common option, in demand in new buildings and in new country houses with autonomous communications;
• D- the designation of switches that instantly break the network when a current flows with a force exceeding the nominal value from 10 to 14, sometimes up to 20 times. Devices with such characteristics are needed only to protect the wiring of powerful electric motors.

There are variations abroad, both up and down, but they should not be of interest to the average owner of domestic property.

Current limiting class and its meaning

This is brief, because most of the devices offered by the trade belong to the 3rd class of current limitation. Occasionally meets the 2nd. This is an indicator of the speed of the device. The higher it is, the faster the device will respond to TKZ.

There is a lot of information, but without it it will be difficult to choose the right circuit breaker and protect property from unwanted fires. Information is also needed for those who will order the installation of protection devices. After all, not every electrician who positions himself as a great specialist should be unconditionally trusted.

From the very beginning of the emergence of electricity, engineers began to think about the safety of electrical networks and devices from current overloads. As a result, many different devices have been designed that are distinguished by reliable and high-quality protection. One of the latest developments has become electric machines.

This device is called automatic due to the fact that it is equipped with the function of turning off the power in automatic mode, in the event of short circuits, overloads. Conventional fuses after operation must be replaced with new ones, and the machines can be turned on again after the causes of the accident have been eliminated.

Such a protective device is necessary in any electrical network scheme. The circuit breaker will protect the building or premises from various emergencies:

• Fires.
• Electric shocks to a person.
• Electrical faults.

Types and design features

Need to know information about existing types circuit breakers in order to select the right device at the time of purchase. There is a classification of electric machines according to several parameters.

Breaking capacity

This property determines the short circuit current at which the machine will open the circuit, thereby turning off the network and the devices that were connected to the network. According to this property, automata are divided into:

• Automatic machines for 4500 amperes are used to prevent malfunctions in the power lines of old residential buildings.
• At 6000 amperes, they are used to prevent accidents during short circuits in the network of houses in new buildings.
• At 10,000 amps, used in industry for protection electrical installations. A current of this magnitude can be formed in the immediate vicinity of the substation.

The operation of the circuit breaker occurs during short circuits, accompanied by the occurrence of a certain amount of current.

The machine protects the wiring from damage to the insulation by high current.

Number of poles

This property tells us about the largest number of wires that can be connected to the machine to provide protection. In the event of an accident, the voltage at these poles is turned off.

Features of machines with one pole

Such electric machines are the simplest in design, and serve to protect individual sections of the network. Two wires can be connected to such a circuit breaker: an input and an output.

The task of such devices is to protect electrical wiring from overloads and short circuits of wires. The neutral wire is connected to the neutral bus, bypassing the machine. Grounding is connected separately.

Electric machines with one pole are not introductory, since when it is turned off, the phase breaks, and the neutral wire still remains connected to the power supply. It does not provide 100% protection.

Properties of automata with two poles

In cases where an accident requires a complete disconnection from the electrical network, use circuit breakers with two poles. They are used as input. In emergency cases, or in case of a short circuit, all electrical wiring is turned off at the same time. This makes it possible to carry out repair and maintenance work, as well as work on connecting equipment, since complete safety is guaranteed.

Two-pole electric machines are used when it is necessary to have a separate switch for a device powered by a 220 volt network.

An automatic machine with two poles is connected to the device using four wires. Of these, two come from the power supply, and the other two come out of it.

Three-pole electric machines

In an electrical network with three phases, 3-pole machines are used. Grounding is left unprotected, and the phase conductors are connected to the poles.

A three-pole machine serves as an input device for any three-phase load consumers. Most often, this version of the machine is used in industrial environment for powering electric motors.

6 conductors can be connected to the machine, three of which are the phases of the electrical network, and the remaining three are coming from the machine and provided with protection.

Using a four-pole machine

To provide protection three-phase network with a four-wire system of conductors (for example, an electric motor connected according to the "star" scheme), a 4-pole circuit breaker is used. He plays the role input device four-wire network.

It is possible to connect eight conductors to the device. On the one hand - three phases and zero, on the other hand - the output of three phases with zero.

Time-current characteristic

When devices that consume electricity and the electrical network are operating normally, normal current flow occurs. This phenomenon also applies to the electric machine. But, in the event of an increase in current strength for various reasons above the nominal value, the automatic release trips, and the circuit breaks.

The parameter of this operation is called the time-current characteristic of the electric machine. It is the dependence of the time of operation of the machine and the ratio between the real strength of the current passing through the machine and the nominal value of the current.

The importance of this characteristic lies in the fact that the least number of false positives is provided on the one hand, and current protection is carried out, on the other hand.

In the energy industry, there are situations when a short-term increase in current is not associated with an accident, and the protection should not work. It also happens with electric machines.

Time-current characteristics determine how long the protection will operate, and what current strength parameters will occur. The greater the overload, the faster the machine will work.

Electric machines marked "B"

Automatic switches of category "B" are able to turn off in 5 - 20 s. In this case, the current value is from 3 to 5 nominal current values ​​≅0.02 s. Such machines are used to protect household appliances, as well as all electrical wiring in apartments and houses.

Properties of machines marked "C"

Electric machines of this category can turn off in 1 - 10 s, at 5 - 10 times the current load ≅0.02 s. These are used in many areas, most popular for houses, apartments and other premises.

The meaning of the marking "D" on the machine

With this class, automata are used in industry and are made in the form of 3-pole and 4-pole versions. They are used to protect powerful electric motors and various three-phase devices. Their operation time is up to 10 seconds, while the operation current can exceed the nominal value by 14 times. This makes it possible to use it with the necessary effect to protect various circuits.

Electric motors with significant power are most often connected through electric machines with characteristic "D", because. starting current is high.

Rated current

There are 12 versions of automatic machines, which differ in the characteristics of the rated operating current, from 1 to 63 amperes. This parameter determines the speed at which the machine switches off when the current limit is reached.

The machine for this property is selected taking into account the cross-section of the conductors of the wires, the allowable current.

The principle of operation of electric machines

normal mode

During normal operation of the machine, the control lever is cocked, current flows through the power wire at the top terminal. Next, the current goes to the fixed contact, through it to the moving contact and through the flexible wire to the solenoid coil. After it, the current goes through the wire to the bimetallic release plate. From it, the current passes to the lower terminal and further to the load.

Overload mode

This mode occurs when the rated current of the machine is exceeded. The bimetallic plate is heated by a large current, bends and opens the circuit. The action of the plate requires time, which depends on the value of the passing current.

The circuit breaker is an analog device. There are certain difficulties in setting it up. The tripping current of the release is adjusted at the factory with a special adjusting screw. After the plate has cooled down, the machine can function again. The temperature of the bimetal strip depends on the environment.

The release does not act immediately, allowing the current to return to its nominal value. If the current does not decrease, the release trips. Overload can occur due to powerful devices on the line, or connecting several devices at once.

Short circuit mode

In this mode, the current increases very quickly. The magnetic field in the solenoid coil moves the core, which activates the release, and disconnects the contacts of the power supply, thereby removing the emergency load of the circuit and protecting the network from possible fire and destruction.

The electromagnetic release operates instantly, which is different from the thermal release. When the contacts of the working circuit are opened, an electric arc appears, the magnitude of which depends on the current in the circuit. It causes destruction of contacts. To prevent this negative effect, an arc chute is made, which consists of parallel plates. In it, the arc fades and disappears. The resulting gases are discharged into a special hole.

The main difference between these switching devices and all other similar devices is a complex combination of abilities:

1. maintain nominal loads in the system for a long time due to the reliable transmission of powerful electricity flows through their contacts;

2. protect operating equipment from accidental malfunctions in wiring diagram at the expense fast withdrawal food from him.

Under normal operating conditions of the equipment, the operator can manually switch the loads with circuit breakers, providing:

different power schemes;

changing the network configuration;

decommissioning equipment.

Emergency situations in electrical systems occur instantly and spontaneously. A person is not able to quickly respond to their appearance and take measures to eliminate them. This function is assigned to automatic devices built into the switch.

In the energy sector, the division of electrical systems by types of current is accepted:

constant;

alternating sinusoidal.

In addition, there is a classification of equipment according to the magnitude of the voltage on:

low voltage - less than a thousand volts;

high voltage - everything else.

For all types of these systems, their own circuit breakers are created, designed for repeated operation.

AC circuits

According to the power of the transmitted electricity, circuit breakers in AC circuits are conventionally divided into:

1. modular;

2. molded case;

3. power air.

Modular designs

Specific execution in the form of small standard modules with a width multiple of 17.5 mm determines their name and design with the possibility of mounting on a DIN rail.

The internal structure of one of these circuit breakers is shown in the picture. Its body is completely made of durable dielectric material, excluding .

The supply and outgoing wires are connected to the upper and lower terminal clamp, respectively. For manual control of the circuit breaker state, a lever with two fixed positions is installed:

the upper one is designed to supply current through a closed power contact;

lower - provides a break in the power circuit.

Each of these automata is designed for long-term operation at a certain value (In). If the load becomes greater, then the power contact breaks. For this, two types of protection are placed inside the case:

1. thermal release;

2. current cutoff.

The principle of their operation makes it possible to explain the time-current characteristic, which expresses the dependence of the protection response time on the load or accident current passing through it.

The graph shown in the picture is for one specific circuit breaker, when the cut-off operating zone is selected to be 5÷10 times the rated current.

During the initial overload, a thermal release operates, made of which, with increased current, gradually heats up, bends and acts on the tripping mechanism not immediately, but with a certain time delay.

In this way, it allows small overloads associated with short-term connection of consumers to self-eliminate and eliminate unnecessary disconnections. If the load provides critical heating of the wiring and insulation, then the power contact breaks.

When an emergency current arises in the protected circuit, capable of burning the equipment with its energy, then the electromagnetic coil comes into operation. It impulse due to the surge of the load that has arisen throws the core onto the tripping mechanism in order to instantly stop the transcendental mode.

The graph shows that the higher the short-circuit currents, the faster they are turned off by the electromagnetic release.

According to the same principles, a household automatic steam fuse works.

When high currents break, an electric arc is created, the energy of which can burn out the contacts. To exclude its action in circuit breakers, an arc chute is used, which divides the arc discharge into small flows and extinguishes them due to cooling.

Multiplicity of cut-offs of modular structures

Electromagnetic releases are configured and selected to work with certain loads because they create different transients at start-up. For example, during the switching on of various lamps, a short-term inrush current due to the changing resistance of the filament can approach three times the nominal value.

Therefore, for the outlet group of apartments and lighting circuits, it is customary to choose circuit breakers with a time-current characteristic of type "B". It is 3÷5 In.

Asynchronous motors, when spinning the rotor with the drive, cause higher overload currents. For them, automatic machines with the characteristic “C” are selected, or - 5 ÷ 10 In. Due to the created time and current margin, they allow the motor to spin up and guarantee to reach the operating mode without unnecessary shutdowns.

V industrial productions on machines and mechanisms there are loaded drives connected to engines that create more increased overloads. For such purposes, circuit breakers of characteristic "D" with a rating of 10 ÷ 20 In are used. They have proven themselves well when working in circuits with active-inductive loads.

In addition, automata have three more types of standard time-current characteristics that are used for special purposes:

1. "A" - for long wiring with an active load or protection of semiconductor devices with a value of 2 ÷ 3 In;

2. "K" - for pronounced inductive loads;

3. "Z" - for electronic devices.

In the technical documentation different manufacturers the cutoff actuation ratio for the last two types may differ slightly.

This class of devices is capable of switching higher currents than modular designs. Their load can reach up to 3.2 kiloamperes.

They are manufactured according to the same principles as modular structures, but, taking into account the increased requirements for the transmission of increased loads, they are trying to give them relatively small dimensions and high technical quality.

These machines are designed for safe operation in industrial facilities. By the value of the rated current, they are conditionally divided into three groups with the possibility of switching loads up to 250, 1000 and 3200 amperes.

The design of their housing: three- or four-pole models.

Power air circuit breakers

They work in industrial plants and operate with currents of very large loads up to 6.3 kiloamperes.

These are the most complex devices of switching devices of low-voltage equipment. They are used for the operation and protection of electrical systems as incoming and outgoing devices of high-power switchgear and for connecting generators, transformers, capacitors or large electric motors.

A schematic representation of their internal structure is shown in the picture.

Here, a double break of the power contact is already used and arc chute chambers with gratings are installed on each side of the disconnection.

The switching coil, the closing spring, the motor drive for charging the spring and the automation elements are involved in the operation algorithm. To control the flowing loads, a current transformer with a protective and measuring winding is built in.

Circuit breakers of high-voltage equipment are very complex technical devices and are made strictly individually for each voltage class. They are usually used.

They are required to:

high reliability;

security;

speed;

ease of use;

relative noiselessness during operation;

optimal cost.

Loads that break during emergency shutdown are accompanied by a very strong arc. To extinguish it, various ways, including breaking the circuit in a special environment.

This switch includes:

contact system;

arc extinguishing device;

live parts;

insulated body;

drive mechanism.

One of these switching devices is shown in the photograph.

For quality work circuits in such designs, in addition to the operating voltage, take into account:

the nominal value of the load current for its reliable transmission in the on state;

the maximum short-circuit current in terms of the effective value that the tripping mechanism can withstand;

permissible component of the aperiodic current at the moment of circuit break;

the possibility of automatic reclosing and the provision of two AR cycles.

According to the methods of extinguishing the arc during shutdown, the circuit breakers are classified into:

oil;

vacuum;

air;

SF6;

autogas;

electromagnetic;

autopneumatic.

For reliable and convenient operation, they are equipped with a drive mechanism that can use one or more types of energy or combinations thereof:

cocked spring;

lifted load;

compressed air pressure;

electromagnetic pulse from the solenoid.

Depending on the conditions of use, they can be designed to operate under voltage from one to 750 kilovolts inclusive. Naturally they have different design. dimensions, possibilities of automatic and remote control, protection settings for safe operation.

Auxiliary systems of such circuit breakers can have a very complex branched structure and be placed on additional panels in special technical buildings.

DC circuits

These networks also have a huge number of circuit breakers with different capabilities.

Electrical equipment up to 1000 volts

Here, modern modular devices that can be mounted on a Din-rail are being massively introduced.

They successfully complement the classes of old automata such as , AE and other similar ones, which were fixed on the walls of the shields with screw connections.

Modular DC designs have the same design and operating principle as their AC counterparts. They can be performed by one or several blocks and are selected according to the load.

Electrical equipment above 1000 volts

High-voltage circuit breakers for direct current operate at electrolysis plants, metallurgical industrial facilities, railway and urban electrified transport, and energy enterprises.

The main technical requirements for the operation of such devices correspond to their analogues on alternating current.

hybrid switch

Scientists from the Swedish-Swiss company ABB managed to develop a high-voltage DC switch that combines two power structures in its device:

1. SF6;

2. vacuum.

It is called hybrid (HVDC) and uses the technology of sequential arc extinguishing in two environments at once: sulfur hexafluoride and vacuum. For this, the following device is assembled.

On the top tire of the hybrid vacuum circuit breaker voltage is supplied, and from the lower busbar of the gas-insulated one it is removed.

The power parts of both switching devices are connected in series and controlled by their individual drives. In order for them to work simultaneously, a synchronized coordinate operations control device was created, which transmits commands to a control mechanism with independent power supply via a fiber optic channel.

Through the use of high-precision technologies, the design developers managed to achieve consistency in the actions of the actuators of both drives, which fits into a time interval of less than one microsecond.

The circuit breaker is controlled by a relay protection unit built into the power line through a repeater.

The hybrid circuit breaker made it possible to significantly increase the efficiency of composite SF6 and vacuum structures by using their combined characteristics. At the same time, it was possible to realize advantages over other analogues:

1. the ability to reliably turn off short-circuit currents at high voltage;

2. the possibility of a small effort for switching power elements, which made it possible to significantly reduce the dimensions and. respectively, the cost of equipment;

3. the availability of various standards for the creation of structures operating as part of a separate circuit breaker or compact devices at one substation;

4. ability to eliminate the consequences of a rapidly increasing restoring voltage;

5. the possibility of forming a basic module for working with voltages up to 145 kilovolts and above.

A distinctive feature of the design is the ability to break the electrical circuit in 5 milliseconds, which is almost impossible to perform with power devices of other designs.

The hybrid circuit breaker device was named one of the top ten developments of the year by the technological review MIT (Massachusetts Institute of Technology).

Other manufacturers of electrical equipment are also engaged in similar studies. They also achieved certain results. But ABB is ahead of them in this matter. Its management believes that large losses occur during the transmission of AC electricity. They can be significantly reduced by using high voltage DC circuits.

Electricity is a very useful and at the same time dangerous invention. In addition to the direct impact of current on a person, there is also a high probability of fire if the electrical wiring is not connected. This is explained by the fact that the electric current, passing through the conductor, heats it, and especially high temperatures occur in places with poor contact or in the event of a short circuit. To prevent such situations, machines are used.

What's happened

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

The method of their work is based on opening the electrical circuit in several cases:

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

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

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 that does not work can overheat the wiring and, as a result, cause a fire.

The installation of low power circuit breakers will break the circuit every time as soon as two or more powerful consumers are connected to the network.

What is the machine made of?

A typical machine consists of the following elements:

• Platoon handle. With it, you can turn on the machine after it is triggered, or turn it off to de-energize the circuit.
• Switching mechanism.
• Contacts. Provide connection and break of the chain.
• Terminals. Connect to a protected network.
• Conditional mechanism. For example, a bimetallic thermal plate.
• Many models may have an adjusting screw to adjust the current rating.
• Arcing mechanism. Present at each of the poles of the device. It is a small chamber in which copper-plated plates are placed. 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.

Trip mechanism device

The machines have an element that breaks the electrical circuit at critical current values. Their principle of operation can be based on different technologies:

• Electromagnetic devices. Differ in the high speed of reaction to short circuit. Under the action of currents of an unacceptable value, a coil with a core is activated, 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, it has a physical effect on the element that breaks the chain. Approximately the same scheme works Electric kettle, which is able to turn itself off when water boils in it.
• There are also semiconductor open circuit systems. But in household networks they are used extremely rarely.

by current values

Devices differ in the nature of the response to an excessively high current value. There are 3 most popular types of automata - B, C, D. Each letter means the sensitivity coefficient of the device. For example, an automaton of type D has a value between 10 and 20 xln. What does it mean? Very simple - to understand the range at which the machine is able to work, you need to multiply the number next to the letter by the value. That is, a device marked D30 will turn off at 30 * 10 ... 30 * 20 or from 300 A to 600 A. But such machines are used mainly in places with consumers that have high starting currents, for example, electric motors.

Type B automaton has a value between 3 and 5 xln. Therefore, marking B16 means operation at currents from 48 to 80A.

But the most common type of machines is C. It is used in almost every home. Its characteristics are from 5 to 10 xln.

Conventions

Different types of machines are marked in their own way for quick identification and selection of the right one 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. Let's analyze in more detail the signs and numbers applied to the machine:

• 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 of your favorite company.
• indicator window. Shows the current status of the 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, it means the tripping characteristic at currents that are much higher than the rated current. C is used more often in everyday life and B is slightly less common. The differences between the types of electric machines B and C are not so significant;
• Rated current. Shows the value of the current that can withstand a continuous load.
• Rated voltage. Very often, this indicator has two values, 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 a voltage of 220 V is used.
• Breaking current limit. It means the maximum allowable short-circuit current at which the machine will turn off without failure.
• Current limiting class. Expressed in one digit or absent altogether. In the latter case, it is customary to consider the class number 1. This characteristic means the time for which the short-circuit current is limited.
• Scheme. On the machine, you can even find a connection diagram for contacts with their designations. It is located almost always in the upper right part.

Thus, 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.

Which to choose?

When choosing a protective device, one of the main characteristics is considered to be the rated current. 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 wires, the current required for heating depends on its cross section.

The presence of poles also plays an important role. The most commonly used practice is:

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

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

• When choosing, you should focus not on electrical appliances, but on wiring, since it will be protected by circuit breakers. If it is old, it is recommended to replace it so that you can use the most best option machine.
• For spaces such as a garage or for the duration of a repair work it is worth choosing an automatic machine with a larger rated current, since various machines or welders have relatively large currents.
• It makes sense to complete the entire set of protective mechanisms from the same manufacturer. This will help to avoid a mismatch in the rated currents between the devices.
• It is better to buy vending machines in specialized stores. So you can avoid buying a low-quality fake, which can lead to disastrous consequences.

Conclusion

No matter how simple the wiring of the circuit around the room may seem, you should always remember about safety. The use of automatic machines largely helps to avoid overheating and, as a result, its ignition.