Operating principle and types of electric machines. Types of circuit breakers - what types of circuit breakers are there? What currents are there circuit breakers for?

Electricity is 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 properly connected. This is explained by the fact that electricity, passing through the conductor, heats it, and especially high temperatures occur in places with poor contact or during a short circuit. To prevent such situations, automatic machines are used.

What's happened

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

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

short circuit;
exceeding the current flowing through a conductor not intended for this purpose.

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

At first glance, it may seem that it is enough to simply install the most powerful machine and there will be no problems. However, it is not. Current great strength, which did not work, can overheat the wiring and, as a result, cause a fire.

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

What does the machine consist of?

A typical machine consists of the following elements:

Cocking handle. Using it, you can turn on the machine after it has been triggered or turn it off to de-energize the circuit.
Switching mechanism.
Contacts. Provide connection and breaking of the circuit.
Terminals. Connect to a protected network.
A condition-triggered mechanism. For example, a bimetallic thermal plate.
Many models may have an adjusting screw to adjust the nominal current value.
Arc extinguishing mechanism. Present at each pole of the device. It is a small chamber in which copper-plated plates are placed. On them the arc is extinguished and comes to naught.

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

Trip mechanism design

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

Electromagnetic devices. They are characterized by a high speed of response to a short circuit. When currents of unacceptable magnitude are applied, the coil with the core is activated, which, in turn, turns off the circuit.
Thermal. The main element of such a mechanism is a bimetallic plate, which begins to deform under the load of high currents. By bending, it has a physical effect on the element that breaks the chain. It works roughly the same way Electric kettle, which can turn itself off when the water in it boils.
There are also semiconductor circuit breaking systems. But they are used extremely rarely in household networks.

by current values

The devices differ in the nature of their response to excessive high value current There are 3 most popular types of machines - B, C, D. Each letter indicates the sensitivity coefficient of the device. For example, a type D machine has a value from 10 to 20 xln. What does it mean? It’s very simple - to understand the range at which the machine is capable of operating, 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 machine has a value from 3 to 5 xln. Therefore, marking B16 means operation at currents from 48 to 80A.

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

Legend

Different types of machines are marked in their own way for quick identification and selection of the one needed for a specific circuit or its section. As a rule, all manufacturers adhere to one mechanism, which allows them to unify products for many industries and regions. Let’s take a closer look at the signs and numbers printed on 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 choosing a product from your favorite company will not be difficult.
Indicator window. Shows the current status of contacts. If a malfunction occurs 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 a shutdown characteristic at currents significantly exceeding the rated current. C is used more often in everyday life and B is used a little less often. Differences between types electric machines B and C are not that significant;
Rated current. Shows the current value that can withstand a long-term load.
Rated voltage. Very often this indicator has two meanings, written separated by 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.
Switch-off current limit. It means the maximum permissible 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, the class number is considered to be 1. This characteristic means the time for which the short circuit current is limited.
Scheme. On the machine you can even find a diagram for connecting contacts with their designations. It is almost always located in the upper right part.

Thus, by looking at the front of the machine, you can immediately determine 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 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 devices and sockets to which simple devices will be connected.
Two poles. Used to protect wiring connected to electric stoves, washing machines, heating devices, water heaters. It can also be installed as protection between the shield and the room.
Three poles. Used primarily in three-phase circuits. This is relevant for industrial or near-industrial premises. Small workshops, production and the like.

The tactics for installing machine guns proceed from larger to smaller. That is, first it is mounted, for example, double-pole, then single-pole. Next come devices with power that decreases at each step.

When choosing, you should focus not on electrical appliances, but on the wiring, since this is what the circuit breakers will protect. If it is old, it is recommended to replace it so that you can get the most out of it. best option machine.
For premises such as a garage, or during the event repair work It’s worth choosing a machine with a higher rated current, since different machines or welders have quite high current ratings.
It makes sense to complete the entire set of protective mechanisms from the same manufacturer. This will help avoid mismatches in current ratings between devices.
It is better to purchase machines in specialized stores. This way you can avoid buying a low-quality fake, which can lead to disastrous consequences.

Conclusion

No matter how simple it may seem to wire a circuit around a room, you should always remember about safety. The use of automatic machines greatly helps to avoid overheating and, as a consequence, fire.

Installation of protective equipment - important stage when building electrical networks. In the event of large currents, heating occurs, causing the melting of the insulating layer of the conductor. This situation leads to a fire. A sharp increase in the current value is associated with a short circuit that occurs during the operation of faulty equipment.

To avoid the risk of fire and damage to wires, various types of electrical circuit breakers are used, depending on the parameters of the electrical devices used in conjunction with them.

Operating principle and varieties

The operating principle of electrical switches is to break the electrical circuit when a short circuit occurs. Or exceeding the permissible power for which the electrical network is designed. Electrical circuit breakers are always located at the beginning of the protected section of the circuit. In this case, the type of connected load does not matter.

Based on their type and parametric values, automata are divided into:

by number of poles;
according to the time-current characteristic;
by rated current.

It is also necessary to note the current limiting class. This value characterizes the speed of the device’s response to an emergency situation. The division occurs into three classes. For domestic use, the third class is used.

Regardless of their characteristics, the operating principle of all switches is identical. To connect the machine to the electrical network, you must set the control switch to the “on” position. The current entering the switch is supplied through the input terminal to the solenoid coil, and from it to the bimetallic plate. The plate is a strip of two pressed metals with different coefficients of linear thermal expansion. The current from the plate arrives at the output terminal and then enters the electrical circuit. The plate and solenoid are called releases.

Current release - important element designs, it can be:

electromagnetic (solenoid);
thermal (bimetallic plate);
combined (combination of thermal and electromagnetic);
independent (by remotely acting on the switch, it turns it off).

There are two conditions under which the electrical switch will trip to disconnect the line: overload mode and short circuit mode.

The principle of operation in overload mode is based on the ability of a bimetallic strip to bend under the influence of heat. As the power on the line increases, the current flowing through the electrical machine increases, exceeding the operating value switch. As a result, the release heats up, its plate bends, and the contact breaks. Accordingly, the electrical circuit is broken. The current supply stops. The amount of current at which the plate breaks the contact is adjusted at the factory using an adjustment screw. After the plate cools, it returns to its previous shape and contact appears again.

In short circuit mode, the current increases very quickly, and the magnetic field it creates in the solenoid sets the core in motion. The core acts on the release, and the electrical circuit is broken, and an arc appears. The appearance of an arc has a negative impact on internal parts machine, so they use a device to extinguish it. The arcing chamber is made of plates located parallel to each other, through which the arc is dissipated.

Thus, the main structural parts can be noted:

current terminals;
release:
control lever;
release adjusting screw;
arc suppression chamber.

Number of poles

The number of poles indicates how many wires can be passed through the switch at the same time. There are devices with the number of pins from one to four. The design of a single-pole switch is no different from a multi-pole one, only in the second case, when passage of electric current Several chains are broken at the same time.

Single-pole devices are more often used in living conditions and are placed in the break of the phase wire, the neutral is connected directly through the block, its use as an input circuit breaker is not recommended. For installation at the input, two-pole circuit breakers are used; the phase and neutral wires are simultaneously connected to them. For use in a three-phase network, a three-pole circuit breaker is used as an input circuit breaker. To protect a four-phase electrical network, for example, a star-connected motor, a four-phase circuit breaker is used. In this case, three phase and one neutral wires are connected.

The usual scheme for constructing a defense on electrical switches comes down to installing an input circuit breaker with the required number of poles. After it, single-pole ones are installed - one for each group. In this case, the rated current of a single-pole circuit breaker is calculated based on the parameters of the group to which it is connected. Its value is chosen less than the input value.

Time-current characteristic

This parameter indicates the ratio of the actual current passed through the machine to the rated value. Depending on the value of the ratio, the sensitivity of the machine is determined, which is characterized by the number of false positives. There are slot machines various types. They are marked with letters of the Latin alphabet. The most widely used switches are those marked B, C and D.

Electrical machines with characteristic B switch off within 5-20 seconds. In this case, the current value can exceed the rated value by five times. These models have become widespread in household premises. Marking C means shutdown interval 1−10 seconds, with a tenfold load. Class D circuit breakers are used to protect engines. The operating current exceeds the rated current by 14–20 times.

Rated current

Indicates the amount of current that can pass through an electrical circuit breaker without tripping it. Issued strictly certain value from 1 to 63 amperes. There are 12 values in total: 1A, 2A, 3A, 6A, 10A, 16A, 20A, 25A, 32A, 40A, 50A, 63A.

The choice of rated current depends on the amount of power that the wiring can withstand without damage. This value is determined by the cross-section of the wire and the material of its manufacture. In homes, the most popular circuit breakers for use are 6A, 10A and 16A. Automatic machines with a nominal value of 20A, 25A, 32A are used in apartments as input ones, that is, two-pole.

Location and accommodation

The placement method (whether it is a single-phase electric machine or another type) is strictly vertical. The fixed part of the control lever should be on top, i.e. the device is turned on by switching from bottom to top. Devices are placed in accessible places, while eliminating the possibility of mechanical damage.

The most popular is the DIN rail mounting. Typically, such a rail is installed in the shield. Electrical switches Structurally, they have special grooves into which the rail is inserted.

What kind of machines there are, how they are marked - you need to know this information in order to choose the right device. Regardless of the manufacturer and type of electric machines, they always have markings on the front side. Marking is carried out according to a single scheme. It includes an indication of all the main parameters:

Inscriptions are made on the control lever indicating the set position - “on.” and "off" or "1" and "0".

Leading brands and manufacturers

The leaders in the production of circuit breakers are the following brands:

These are well-known brands that produce all types of electrical machines. They differ high quality housing, long service life and high mechanical strength. Often, protective covers are additionally installed on them. These manufacturers make their devices from high-quality materials. Their quality is confirmed by certificates and the warranty period provided by manufacturers for their products.

Circuit breakers are devices that provide protection for wiring in short circuit conditions when connecting a load with values exceeding the established values. They should be selected from special attention. It is important to consider the types of circuit breakers and their parameters.

Vending machines of different types

Characteristics of machines

When choosing a circuit breaker, it makes sense to focus on the characteristics of the device. This is an indicator by which you can determine the sensitivity of the device to possible excess current values. Different types circuit breakers have their own marking - it is easy to understand how quickly the equipment will respond to excess current values to the network. Some switches respond instantly, while others activate over a period of time.

A is a marking that is affixed to the most sensitive equipment models. Automatic machines of this type immediately register the fact of overload and promptly respond to it. They are used to protect equipment characterized by high precision, but it is almost impossible to find them in everyday life.
B is a characteristic possessed by switches that operate with an insignificant delay. In everyday life, switches with the appropriate characteristics are used together with computers, modern LCD TVs and other expensive household appliances
C is a characteristic of machines that are most widely used in everyday life. The equipment begins to function with a slight delay, which is sufficient for a delayed response to registered network overloads. The network is switched off by the device only if it has a fault that really matters
D - characteristic of switches with minimal sensitivity to excess current. Basically, such devices are used to supply electricity to a building. They are installed in panels and control almost all networks. Such devices are chosen as a backup option, since they are activated only if the machine does not turn on in time.

All parameters of circuit breakers are written on the front part

Important! Experts believe that the ideal performance of circuit breakers should vary within certain limits. Maximum - 4.5 kA. Only in this case the contacts will be under reliable protection, and current discharges will be discharged under any conditions, even if the established values are exceeded.

Types of machines

The classification of circuit breakers is based on their types and features. As for types, we can highlight the following:

Rated breaking capacity - we are talking about the resistance of the switch contacts to the effects of high currents, as well as to conditions in which deformation of the circuit occurs. Under such conditions, the risk of burning increases, which is neutralized by the appearance of an arc and an increase in temperature. The higher quality and durable the equipment is made of, the higher its corresponding capabilities are. Such switches are more expensive, but their characteristics fully justify the price. Switches last a long time and do not require regular replacement
Rating calibration - we are talking about the parameters in which the equipment operates in normal mode. They are installed at the production stage of the equipment, and are not regulated during its use. This characteristic allows you to understand how strong overloads the device can withstand, the period of time it operates in such conditions
Setpoint - usually this indicator is displayed as a marking on the equipment body. We are talking about maximum current values under non-standard conditions, which, even with frequent shutdowns, will not have any effect on the operation of the device. The setting is expressed in current units, marked in Latin letters, digital values. The numbers, in this case, reflect the denomination. Latin letters can be seen in the markings of only those machines that are manufactured in accordance with DIN standards

Drivers of cars equipped with a manual gearbox, from time to time, in order to engage the desired gear, have to control the car using only one hand. In contrast, happy owners of vehicles with an automatic gearbox can hold the steering wheel with both hands throughout the entire movement. And now we will look at the basic types of automatic transmissions.

Summary :

Types of automatic transmission | Types of automatic transmissions

Classic hydraulic “Automatic” (automatic transmission) | Hydraulic automatic

A striking example of a classic automatic transmission is precisely hydraulic type automatic transmission, aka hydraulic automatic machine. The absence of a direct connection between the engine and the wheels is the peculiarity of of this type automatic transmission The question arises: how is torque transmitted? The answer is simple - two turbines and working fluid. As a result of the further “evolution” of this type of “automatic”, the role of control in them was taken over by specialized electronic devices, which made it possible to add special “winter” and “sport” modes to such automatic transmissions, a program for economical driving and the ability to change gears “manually” appeared. .

Unlike a manual gearbox, a hydraulic “automatic” requires slightly more fuel and takes longer to accelerate. But this is the price you have to pay for comfort. And it was “hydraulics”, challenging “mechanics”, that won a landslide victory in many countries, except for “old Europe”.

How does an automatic transmission work?

Drivers in Europe long time All types of automatic transmission was categorically not accepted. The engineers had to do a lot before finally adapting the automatic gearbox for Europe. But all this ultimately served to increase efficiency and the emergence of such modes as “winter” and “sport”. In addition, the box learned to adapt individually to the driver’s driving style, and it became possible to manually change gears with an automatic transmission - which was important for European drivers.

Each manufacturer preferred to call such transmissions in its own way, but the very first name to appear was - Autostick. One of the most widespread inventions today is considered to be the invention of the AUDI company - Tiptronic. BMW, for example, called such a transmission - Steptronic, Volvo considered appropriate name for automatic transmission Geartronic.

However, even though the driver engages the gears himself, he is not considered to be completely manual. This is more semi-automatic, because the transmission computer continues to control the operation of the car regardless of the selected mode.

Robotic gearbox | Automatic robot

MTA (Manual Transmission Automatically Shifted) - or so-called popularly, is structurally, perhaps, in many ways similar to “mechanics”, but from a control point of view, it is nothing more than an automatic transmission. And although fuel consumption here is more moderate than with the same manual transmission, there are also some nuances. The “robot” is very effective only at a very moderate driving pace.

The more aggressive your driving becomes, the more painful the gear changes feel. Sometimes when switching, it may even seem as if someone is pushing you into the rear bumper. That is difference between a robot (DSG) and an automatic machine lies in the principle of operation of the first. However, the low cost and low weight of the automatic transmission completely compensate for this disadvantage.

About the DSG box Video

Why does the Robot need two clutches?

Volkswagen Golf R32 DSG with 2 clutches

Existing shortcomings seriously complicated operation, with a particularly acute impact on driving comfort. Therefore, the designers, during a lengthy “search”, eventually came to a solution that solved the problems - they equipped the “robot” with two clutches.

In 2003, Volkswagen launched a robotic transmission with two clutches into mass production, installing it for the first time on the Golf R32. The name was given to him DSG(Direct Shift Gearbox). Here, even gears were controlled by one clutch disc, and odd gears by a second. This significantly softened the operation of the box, but another serious drawback appeared - the price of this automatic transmission is quite high. Although mass acceptance of such a transmission by car enthusiasts can solve this problem.

CVT | CVT gearbox

CVT transmission (Continuously Variable Transmission) - it changes torque smoothly, this is its feature. This type of automatic transmission does not have steps; its gears do not have a fixed gear ratio. And if we compare it with “hydraulics”, then we can monitor the work of the latter using the tachometer readings, but variable speed drive very measuredly picks up the moments of gear shifting while the speed balance remains unchanged.

CVT | Continuously variable transmission

Useful video about what a CVT transmission is

Features | Differences between a CVT and an automatic transmission.

Those drivers who are accustomed to “listening” to their car will not be able to love such a box, because, like a trolleybus, it does not change the tone of the engine. But it’s probably not worth abandoning the CVT for this reason. Engineers found a way out of this situation by adding a mode where “virtual gears” can be selected manually. The gearshift mode is simulated, allowing the driver to experience driving like a conventional automatic gearbox.

How to determine which gearbox is installed in a car, CVT or hydraulic automatic:

If possible, study technical documentation car. In most cases, the automatic is designated as AT (Automatic Transmission), the variator is designated CVT;
Look for information on the Internet. Usually in technical specifications You will definitely find the answer on popular sites;
Test Drive. If the car is equipped with a variator, then you will not feel any, even subtle jolts or jerks; acceleration is similar to the acceleration of a “trolleybus”. On a classic automatic transmission you can feel the gear changes, although on a working one they are almost invisible, it is impossible not to “feel” them.

What is more reliable and better: a CVT, a robot or an automatic?

If an emergency occurs in the electrical network - a short circuit, fire or electric shock to a person, it must be immediately de-energized. Previously, this function was performed by fuses. Their main disadvantage is that they disconnect only one, and most often only the phase, line.

And according to today’s operating rules for electrical installations, a complete break is required. In addition, they do not act quickly enough and must be replaced after operation. Automatic fuses and switches do not have these disadvantages.

Family electrical devices, which in everyday use are often called “electric machines,” are very diverse. If such a comparison is allowed, it consists of several clans, differing in the type of influence to which they react, as well as in their design.

Depending on this, they are used to protect the entire electrical network as a whole, individual circuits and devices, or a person. There is also an intra-clan division. For example, in terms of response speed.

Types of circuit breakers by type of impact:

Triggered by overcurrent (short circuit) and heating. The most common type. They are used to protect the entire power supply circuit (input circuit breakers) or individual devices.
Response to differential current. These are the so-called RCD devices protective shutdown, used to prevent electric shock to a person.
Thermal relays. Used in electric drives to protect electric motors from overloads.

Differences in design:

AP series. The so-called apeshki are large black boxes made of electrical plastic with two buttons: ON (white) and OFF (red). React to heat and overcurrents. Typically used in three-phase networks to protect individual devices. Reliable massive design, considered obsolete.
Series VA. A modern small-sized device with an on/off lever located horizontally.
Automatic fuses. We replaced the so-called plugs with Edison E14 threaded socket. Also outdated, but still widely used in household electrical networks design.

Depending on the number of connection points, which are called poles, switches are one-, two-, three- and four-pole.

Single-pole switches only one line, usually phase. They are used in lightly loaded electrical circuits. For example, lighting. Their second name is “modular circuit breakers”, since they are usually assembled into a package (several per DIN rail) and placed in a distribution board, adjacent to a common zero bus. These also include automatic fuses, the input of which is the central contact, and the output is a threaded ring.

Two-pole ones are used in single-phase networks to protect the entire electrical circuit, then they are called input, or one device.

Three- and four-pole devices are used to operate in three-phase networks, which can have three (in the case of a solidly grounded neutral) or four conductors.

Circuit breaker design

The design principle of switches that respond to overcurrents and overheating is the same as for devices such as AP, VA or automatic fuses. BA type switches have screw terminals. A moving contact is connected to the input, which is connected to the control lever by a system of levers and springs.

When turned on, it has electrical contact with an electromagnetic release - a solenoid with a movable core-rod. The conductor at its output is connected to another control element - a bimetallic plate abutting the rod. Additional element The device is an arc-extinguishing chamber - a package of plates made of electrical fiberboard.

The release is designed to operate when a certain current rating passes through its coil. When this value is reached, the solenoid pushes the rod and opens the contact. Note that the bimetallic strip is connected to the output terminal. Therefore, there is a significant difference in how to install a circuit breaker. When turned upside down, it stops responding to a short circuit due to the additional resistance of the plate.

Residual current circuit breakers

They are called RCDs - residual current devices. Outwardly, they are very similar to VA machines, differing only in the “Test” button. Fundamental differences in the design of the electromagnetic release. It is built on the basis of a differential transformer.

Its primary winding is made up of two coils, to which the phase and neutral wires are connected. The secondary winding is connected by a solenoid. In the normal state, the currents in the phase and neutral conductors are equal in magnitude, but opposite in phase. They compensate each other, and no electromagnetic field is induced in the primary winding.

When there is a partial breakdown of the insulation and the phase line is connected to the ground loop, the balance is disrupted and a magnetic flux appears in the primary winding, generating an electric current in the secondary. The solenoid operates and opens the contact.

This happens if, for example, a person takes with his hand an electrical appliance whose body is shorted to phase. These devices do not protect against short circuits or overheating, so they are installed in series with VA circuit breakers. And definitely after them. About correct connection read .

Differential switches

They are also called residual current circuit breakers - the abbreviation RCBO. They combine a VA machine and an RCD. Their use simplifies electrical diagram and its installation - instead of two devices, you can install one.

You can distinguish a RCBO from an RCD by a schematic image on the front panel, which is not always possible due to insufficient technical literacy, or by the letter in front of the nominal value and its value. Read more about this.

On the residual current device it can be written, for example, I n 16A and I ∆n 10 mA. The first value is the rated current of the circuit in which the device can operate. Note that there is no letter in front of it. The second is the operating current, it never exceeds a few amperes. The RCBO is marked differently: C16 10 mA. Letter C is a time-current characteristic.

Time-current characteristics of circuit breakers

Depending on the design of the magnetic trip solenoid, the circuit breaker may trip with at different speeds. This is called the time-current characteristic. The main ones are:

A – the fastest possible response. Necessary to protect those sensitive to the quality of electricity semiconductor circuits. The device can only operate in conjunction with a compensation-type stabilizer. It is better not to use it at home, since the quality standards for household networks are low, it will constantly work.
B – sensitivity is increased, but the response time is reduced. Can be used to protect power supply circuits of local area networks.
C is the most common type of device used in everyday life. Satisfactory sensitivity and average speed triggering.
B – industrial version with reduced sensitivity. Used in networks with large amplitudes of voltage drops. For example, connected to traction substations of electric vehicles.

Circuit breakers are an important element of an electrical circuit. Operation of electrical installations without them can lead to a local man-made disaster and pose a threat to the lives of operating personnel.