Circuit breakers They are not at all like the usual ones, which are installed in each room to turn the lights on and off (Fig. 1). Their task is somewhat different. Circuit breakers are installed in distribution boards and serve to protect the circuit from power surges and non-periodic power outages in certain sections of the electrical network.
Rice. 1.
Slot machines, as they are more often called, are installed at the entrance to a house or apartment and are located in special boxes, metal or plastic (Fig. 2).
Rice. 2. Switchboard with machine guns
There are many types of circuit breakers. Some of them serve only as circuit breakers and protect the network from overload. These are, for example, the old AE type circuit breakers in a black carbolite case (Fig. 3).
Rice. 3. AE series circuit breaker
In most of the old shields in the entrances residential buildings These are exactly what they cost. However, they are quite reliable and are still in use today.
Modern variations allow additional functions, for example, protection against underload currents.
Based on the response time to unacceptable voltage, automatic machines are divided into 3 types: selective, normal and high-speed. The response time of a normal machine ranges from 0.02 to 0.1 s. In selective circuit breakers this time is the same. High-speed circuit breakers work more quickly - for them this value is only 0.005 s.
All circuit breakers are enclosed in a plastic unbreakable case with a special fastening (bar or rail) on the rear surface. It is very easy to install the machine on such a mount - just insert it onto the rail until it clicks. You can remove it using a screwdriver by lightly pulling the special tab on top of the circuit breaker. This greatly simplifies the task of installing the machine in the cabinet (Fig. 4).
Rice. 4.
Inside the case is the “filling” of the machine, its main safety devices, of which there can be 2 (Fig. 5).
Rice. 5. Internal
We are talking about electromagnetic and thermal releases - unique mechanisms for automatically interrupting the circuit. A bimetallic plate when heated by a current passing through it is unacceptable high value straightens and opens the contacts - this is a thermal release. In terms of response time, it is the slowest.
The electromagnetic release operates according to the “dead hand” rule. The coil, located in the center of the machine, is continuously maintained in place by a stable voltage. As soon as it jumps beyond the nominal limits, the coil literally jumps out of its place, breaking the chain. This method of breaking the chain is the fastest.
All circuit breakers have contacts for connecting incoming and outgoing wires (Fig. 6).
Rice. 6. Wires are connected to the contacts of the circuit breaker using screw terminals
Automatic machines are distinguished by the degree of sensitivity to tripping. In the standard most common models, circuit breakers with a threshold value approximately equal to 140% of the nominal value are most often used. When the voltage increases by one and a half times, the electromagnetic (fast) release is triggered. When the rated voltage is slightly exceeded, the thermal release operates. The shutdown process can last for hours, which greatly depends on the ambient temperature. However, the machine will react to a change in voltage in any case.
Automatic switches are distinguished by the number of poles. What does it mean? One machine can have several independent from each other electrical lines, which are interconnected by a common shutdown mechanism (Fig. 7 and 8). Automatic machines come in one-, two-, three- and four-pole types (this applies to domestic use).
Rice. 7. in a plastic box when turned off
Rice. 8. : All lines are triggered simultaneously when tripping, they are connected together using one lever jumper
The circuit breaker has differences in other respects. They differ in the threshold current strength that they pass through themselves. In order for the machine to operate and turn off the power supply in an emergency, it must be configured to a certain sensitivity threshold. This setting is made by the manufacturer, so the numerical value of this threshold is immediately written on the machine. For domestic needs, machines with ratings of 6.3, 10, 16, 25, 32, 40, 63, 100 and 160 A are used (Fig. 9). There are machines with values of both 1000 and 2600 A, but they are not used in everyday life. These figures mean the total power of all consumers electric current, which will be connected to the circuit “guarded” by the machine.
Machine sensitivity it is necessary to calculate not only the total power of the expected energy consumers, but also the wiring and electrical installation products - sockets and switches.
Table 1 presents the typology of machines.
Table 1. Types of machines
| Type | Purpose |
| A | For breaking long-distance circuits and protecting semiconductor devices |
| B | For general purpose lighting networks |
| C | For lighting circuits and electrical installations with moderate starting currents (motors and transformers) |
| D | For circuits with active-inductive loads, as well as protection of electric motors with high starting currents |
| K | For inductive loads |
| Z | For electronic devices |
Table 2. Two-core copper cable laid in a box
| Section, mm2 | Cable current/1.45, A | Automatic, A | Excess current,% | |
| 1,5 | 19 | 13,1 | 13 | - |
| 2,5 | 27 | 18,62 | 16 | - |
| 4 | 38 | 26,2 | 25 | - |
| 6 | 50 | 34,48 | 32 | - |
| 10 | 70 | 48,27 | 40(50) | 3,5 |
| 16 | 90 | 62,06 | 50(63) | 1,5 |
Table 3. Two-core copper wire laid in a box
| Section, mm2 | Maximum continuous cable current, A | Cable current/1.45, A | Automatic, A | Excess current,% |
| 1 | 15 | 10,34 | 10 | - |
| 1,5 | 18 | 12,41 | 10(13) | 4,7 |
| 2 | 23 | 15,86 | 13(16) | 0,87 |
| 2,5 | 25 | 17,24 | 16 | - |
| 4 | 32 | 22,06 | 20 | - |
| 6 | 40 | 27,58 | 25 | - |
| 10 | 48 | 33,1 | 32 | - |
| 16 | 55 | 37,93 | 32(40) | 5,4 |
The maximum continuous cable current is assumed for a core temperature of +65 and air temperature of +25 °C. The number of simultaneously laid conductors is up to 4. A number of machines: 0.5 A, 1 A, 2 A, 3 A, 4 A, 6 A, 10 A, 13 A, 16 A, 20 A, 25 A, 32 A, 40 A, 50 A and 63 A. Table data. 3 are also suitable for three-core cable. In this case, the third core must be a protective grounding or grounding wire.
Rice. 9. A row of single-pole 16 A circuit breakers. Let’s say that for a separate area in an apartment, for example a kitchen, we have one 6.3 A circuit breaker (it happens, the electricians joked). Using the well-known formula Watt = Volt x Ampere, we calculate how many devices (and which ones) can be powered from our network. It turns out that this value is equal to 1386 W, since the default voltage is 220 V. This means that in such a kitchen it is impossible to turn on even a powerful kettle, not to mention a refrigerator or electric stove - the machine will work instantly and will not allow, in its opinion, unacceptable current to pass through the controlled territory. IN in this case It is urgent to change the circuit breaker to 25 or even 32 A.
Electrical circuit breakers perform the function of protecting wiring from overloads, short circuits, and accidents that may occur during voltage surges. To avoid an emergency, it is necessary in apartments, private houses, garages, cottages and outbuildings install electrical circuit breakers. When overloads or surges occur, the device reacts and operates differently. In one situation or another, it triggers individual parts device, while other parts continue to work, ensuring the safety of the home.
Operating principle of the circuit breaker
The switch has compact, small sizes, the device is placed in plastic made of heat-resistant materials. On one side - the front - there is a handle that allows you to turn the device on and off, on the other - at the back - there is a latch, which is attached to a special DIN rail. Screw terminals are located at the bottom and top.
The operating principle of the switches depends on the state of the network and the flow of current through the wiring. When the electrical switch device is in normal mode, a current flows through the circuit breaker, the indicators of which may be equal to or less than the set nominal value. The voltage from the external network goes to the upper terminal with a fixed contact. From here, the current flows to a closed moving contact, and then passes to the solenoid coil, which is a flexible copper conductor. From here the current goes to the thermal release, from which it flows to the lower terminal. It is she who is connected to the network.
Table of current circuit breaker ratings
The standard current that passes through the wiring may be more or less than the established values. Based on them, a classification of time-current characteristics for releases in devices has been compiled. Each type in state standard marked with a Latin letter, and the permissible excess should be sought using the coefficient formula - k=I/In.
Table 1 shows the norms for each type of time-current indicators.
Table 1
Table 2 shows the time-current characteristics of automatic current switching devices.
table 2
| Type | Characteristic | Types of chains |
| A | Protection on the AB segment is activated when the coefficient is equal to 1.3. The current is turned off within 60 minutes. If the current continues to increase, the shutdown time is reduced by exactly half. Electromagnetic protection at a speed of 0.05 sec. will work if the nominal value exceeds 2 times. | They are not subject to short-term overloads and are used on an industrial scale, not in everyday life. |
| IN | The standard nominal value can be exceeded by 3-5 times. The solenoid is activated if the overload increases by 5 times. Then de-energization will occur within 0.015 seconds. The thermocouple will turn off within 4 seconds. already at three times the excess. | Characteristic for circuits without high inrush currents. |
| WITH | Overload occurs more often than with other types, the permissible indicators are 5 times higher than the norm. As soon as the standard mode is exceeded, the thermoelement will automatically turn off. | In household networks, where there is often a load of different types. |
| D | Exceeding the standard norm occurs 10 times, after which the thermoelement is turned off, and 20 times for the solenoid. | Used to protect starting devices, through which high current passes. |
| TO | The solenoid will turn off if the current exceeds 8 times. | Such devices must be installed on circuits that have an inductive load. |
| Z | A slight excess is typical - from 2 to 4 times. | Used to connect electronic devices. |
| M.A. | The thermocouple is not used to disconnect the load. | Installed on devices with electric motors. |
Selection of circuit breaker by power
One of the main indicators by which a circuit breaker is selected is the load power. This allows you to calculate desired value current for the device, its protection against voltage surges. The calculation is carried out based on the rated current, so it is recommended to select according to the power of individual sections. It is worth taking into account lower or nominal values of calculated currents. The permissible current of the electrical wiring will be greater than the rated power of the circuit breaker.
It is also necessary to take into account such an indicator as the time-current characteristic of the device. The main parameter for determining the rated power is the cross-section of the wire. Permissible value the current indicated on the circuit breaker should be slightly less than the maximum current for the wire cross-section. Select a device based on the smallest cross-section of the wire that is laid in the wiring.
The dangers of a cable mismatch with the network load
If the circuit breaker does not match the network power and load, then it will not protect the wiring from the fact that the current strength and voltage sharply increases or decreases.
The cable cross-section for the network load must exactly match the power of the device. If the total power in different areas is greater than the nominal value, then the temperature will increase. This may cause the cable insulating layer to melt. As a result, a fire will start electrical wiring. Also, if the cable cross-section does not correspond to the load, the following phenomena will be observed:
- Smoke.
- Smell of burnt insulation.
- A flame appears.
- The switch will not be disconnected from the network, since the rated current through the wiring will not exceed permissible limits.
The process of melting the insulating layer will cause a short circuit over time. Next, the circuit breaker will turn off; at this time, the fire can engulf the entire house.
Weak link protection
The rules for electrical installations state that the switch for the electrical network must protect the weakest section as much as possible or contain a current rating that will fully correspond to the parameters of the installations that are included in the network. To connect wires to the network, you need to connect them cross sections had the total power of all connected devices.
Compliance with such rules can protect an apartment or house from an accident due to a weak section of electrical wiring. The described requirements cannot be ignored, since the homeowner is capable of losing not only the automatic power switch device, but also the apartment.
How to calculate the rating of a circuit breaker
- I - indicator/value of rated current.
- P is the total power of all installations that are included in the circuit. Light bulbs and other devices that consume electricity are taken into account.
- U is the current voltage in the network.
To calculate the denomination, you can use Table 3:
| Connection type | Single phase in kilowatts | Three-phase (delta) in kilowatts | Three-phase (star) in kilowatts |
| U, B Automatic, in amperes |
220 | 380 | 220 |
| 1 Ampere | 0,2 | 1,1 | 0,7 |
| 2 | 0,4 | 2,3 | 1,3 |
| 3 | 0,7 | 3,4 | 2 |
| 6 | 1,3 | 6,8 | 4 |
| 10 | 2,2 | 11,4 | 6,6 |
| 16 | 3,5 | 18,2 | 10,6 |
| 20 | 4,4 | 22,8 | 13,2 |
| 25 | 5,5 | 28,5 | 16,5 |
| 32 | 7,0 | 36,5 | 21,1 |
| 40 | 8,8 | 45,6 | 26,4 |
| 50 | 11 | 57 | 33 |
| 63 | 13,9 | 71,8 | 41,6 |
Using Table 3, you can easily calculate how many kilowatts of load a particular type of rated current can withstand. You must select clearly according to the specified values so that the voltage and type of connection exactly match and correspond to each other. This will help avoid excess load and possible accidents.
Unacceptable mistakes when purchasing
Buying a circuit breaker is not something you do every day. Therefore, you need to be careful when choosing a device so as not to cause a fire at home or short circuit the wiring. The following types of mistakes should not be made during purchase:
- Choose the right machine according to the power of electrical wiring in an apartment or private building. Many consumers do exactly the opposite - they focus on the power of the electrical appliances they operate. This is wrong, since the electrical wiring may not withstand it and begin to melt.
- Calculation of the nominal current of the current must be done based on average indicators. This way the wiring will definitely withstand the current load.
- For a dacha or garage, the AB rating should be more powerful, since the equipment used in such places has more power than in an apartment.
- Devices must be purchased only from trusted manufacturers so that all technical specifications are accurate and of high quality and do not threaten the safety of housing and residents.
- You should purchase circuit breakers only in specialized stores, and do not use the services of intermediaries. This eliminates the risk of purchasing counterfeits and low-quality products.
Buying electric machines is not a very difficult task. You should adhere to the above recommendations to avoid mistakes in choosing such a device for your home. It is recommended to purchase a circuit breaker with a person who understands electricity, special equipment, types of cross-sections, device power, network voltages and phases.
The development of power grid security tools has become relevant since their inception. Various overloads led not only to cable damage, but also to fires.
Today, the most popular devices of this type are circuit breakers.
They help prevent events such as fires and damage to electrical wiring. Since they are automatic, operation occurs without human intervention. Choice the correct switch will help protect the premises from accidents.
Design and principle of operation
Understanding the automatic switch operation mechanism will help you select the right model. Structurally, the machine includes the following key elements:
- terminals;
- toggle switch;
- electromagnetic release;
- bimetallic plate.
Depending on the type of overload, one of two mechanisms is triggered.
If a circuit overload occurs with a current that exceeds the nominal value by several times, the bimetallic plate is triggered. It heats up within a few seconds, causing it to expand thermally. Upon reaching certain sizes It bends significantly and the circuit opens. The plate parameters are adjusted by the manufacturer. For switches used in everyday life, the response time takes 5–20 s. They are usually marked with the letters: B, C, D.
Mode short circuit(short circuit) is characterized by an avalanche-like increase in current, exceeding not only the nominal value, but also its maximum permissible loads. There is no time left for heating the plate during the jump, otherwise the wiring may melt. In such a situation, an electromagnetic release is triggered. The magnetic field moves the core, which opens the circuit. Instant operation allows you to protect the premises from the consequences of a short circuit.
Classification
Electric machines differ in the following key characteristics:
- number of poles;
- time current characteristic;
- operating current value;
- breaking capacity.
Number of poles
This characteristic corresponds to the number of electrical wiring lines that can be directly connected to the machine. All output wires will be disconnected simultaneously when the machine is triggered.
Single-pole circuit breaker. This is the simplest type of circuit protection devices. Only 2 wires are connected to it: one goes to the load, the second is power. It is placed on a standard 18 mm din strip. The power wire is supplied from the top, and the load is connected to the bottom terminal. It can work in electrical wiring lines with one, two or three phases. In addition to the power and load wires, it has a neutral and ground, which are connected to the corresponding buses. Such machines are not installed at the entrance, since the circuit will only open along the phase line. The neutral wiring remains closed and in the event of a failure, potential may remain on it.
A two-pole machine, its difference from a single-pole one. This type of circuit breaker allows you to completely cut off the electrical wiring in the room. It allows you to synchronize the moment when you turn off your two output lines. The latter leads to a higher level of safety when carrying out electrical installation work. It can be used as a separate toggle switch for appliances such as a water heater or washing machine. The connection is made using 4 cables: a pair at the input and output.
A simple question is logical: is it possible to connect two single-pole circuit breakers instead of one double-pole one? Of course no. After all, when a two-terminal switch is automatically triggered, all output lines are switched off. For a pair of independent machines, an overload may not occur on one of the lines and the blackout will be partial. In ordinary apartments, you can connect the phase and neutral lines to this machine. When opened, there will be a complete blackout of the entire group of devices that are powered from it.
Three and four pole machines. All three or four phase wires are connected to the poles of the corresponding circuit breaker. They are used when connected by a star, when the phase wires are protected from overloads, and the middle wire remains switched all the time, or by a triangle, when there is no middle central cable, but the phase wires are protected.
If an overload occurs on one of the lines, a shutdown occurs immediately on all the others. These machines are connected to 6 (three-phase machine) or 8 wires. 3-4 at the output and the same number of lines at the output. They are mounted on DIN rails with a length of 54 (three-phase automatic) and 72 mm, respectively. They are used most often in industrial installations, when connecting powerful electric motors.
Time current parameter
The power consumption pattern of different devices varies even if the power values are the same. Uneven dynamics of consumption during correct operation, a surge in load during switching on - all these phenomena lead to significant changes in such a parameter as current consumption. Power dispersion can lead to false tripping of the circuit breaker.
To eliminate such situations, dynamic operating parameters are introduced, called time-current characteristics of circuit breakers. Based on this parameter, machines are divided into several types. The triggering time of the machine is different for each group. The front panel of the switch is marked with the corresponding letter from the list: A, B, C, D, K, Z.
Rated current
The differences in automatic machines depending on the rated current values are divided into several groups (12 current levels). It is directly related to the response time when power consumption is exceeded. Define operating value it is possible purely theoretically by adding up the sums of currents consumed by each device separately. In this case, you should take a small reserve. You should also not forget about the electrical wiring options.
The machines are designed primarily to prevent damage. Depending on the metal of the wires and their cross-section, the maximum load is calculated. The current ratings of circuit breakers allow this division to be made.
Breaking capacity
This parameter depends on the maximum current value when a short circuit occurs, provided that the machine disconnects the network. Based on the magnitude of the short-circuit current, all circuit breakers are divided into three groups.
- The first includes devices with a rating of 4.5 kA. They are used in private houses intended for human habitation. The current limit is approximately 5 kA. This is due to the fact that the resistance of the conductive cable system leading to the house from the substation is 0.05 Ohm.
- The second group has rated 6 kA. This level is already used in residential apartment buildings and public places. The maximum current can reach 5.5 kA (wiring resistance 0.04 Ohm). Models of the following types are used: B, C, D.
- In industrial installations the rating is 10 kA. The maximum current value that can occur in the circuit near the substation has the same value.
How to choose the right machine
Until recently, porcelain fuses with fusible elements were widely used. They were well suited for the same type of load in Soviet apartments. Now the number household appliances became much larger, as a result of which the likelihood of a fire with old fuses increased. To prevent this, you need to carefully select a machine with the right characteristics. Excessive power reserves should be avoided. The final choice is made after completing a few simple steps.
Determination of the number of poles
When determining this switch parameter, you should be guided by simple rule. If you plan to secure sections of the circuit with devices that have low power consumption (for example, lighting devices), then it is better to leave your choice on a single-pole circuit breaker (usually class B or C). If you plan to connect a complex household device with significant power consumption (washing machine, refrigerator), then a two-pole circuit breaker (class C, D) should be installed. If the equipment is small production workshop or a garage with multiphase motor systems, then you should choose a three-pole option (class D).
Power consumption calculation
As a rule, by the time it is planned to connect the machine, the wiring to the room has already been installed. Based on the cross-section of the conductors and the type of metal (copper or aluminum), it is possible to determine maximum power. For example, for a 2.5 mm 2 copper core, this value is 4–4.5 kW. But the wiring is often supplied with a large margin. Yes, and the calculation should be done before all installation work begins.
In this case, you will need a value about how much total power will be used by all devices. It is always possible to turn them on simultaneously. So, in an ordinary kitchen, the following appliances are often used:
- fridge– 500 W;
- Electric kettle– 1700 W;
- microwave– 1800 W
The total load is 4 kW and a 25 A circuit breaker is enough for it. But there are always consumers who turn on sporadically and can create factors that contribute to the circuit breaker tripping. Such devices can be a combine or a mixer. Therefore, you should take a machine with a reserve of 500–1200 W.
Rated current calculation
Since power in single-phase networks is equal to the product of voltage and current, the current can easily be determined as the quotient of power and voltage. For the above example, this value is easy to calculate, knowing that the mains voltage is 220 V. The current consumed is 18.8 A. Taking into account a reserve of 500–1200 V, it will be 20.4–23.6 A.
In order for the work not to stop even with such short-term excess loads, the rated current for the machine can be taken equal to 25 A. The nominal value corresponds to approximately the same value, based on a copper cable with a cross-section of 2.5 mm 2, which is sufficient with a margin for such loads. A circuit breaker with a rated current of 25 A will work before it starts to heat up.
Determination of time current characteristic
This parameter is determined using a special table that lists the starting currents and their flow time. For example, for a household refrigerator, the starting current multiplicity is 5. With a power of 500 W, the operating current is 2.2 A. The starting current value will be 2.2 * 7 = 15.4 A. Periodicity data is also taken from a special table.
Table No. 1. Starting currents and pulse durations for household appliances
For the selected device, this characteristic does not exceed 3 s. The choice becomes obvious: for such a consumer it is necessary to take a type B circuit breaker. It is permissible to select a circuit breaker based on load power. You can skip the last step and opt for a class B switch. For domestic needs, the characteristics of class B and C electrical switches are most often sufficient.
The topic of our article today is the rating of manufacturers of circuit breakers in the domestic and foreign markets. Next, we will tell you which company is better to give preference when choosing an automatic machine, and also provide readers of the site with leading brands that produce automatic equipment for household and industrial use. Will also be provided short review the best economy class AVs, which are most often used in houses and apartments.
Brand overview
So, first, let's briefly talk about the main manufacturers of circuit breakers. As for foreign brands, the most famous are:
- ABB. A Swedish-Swiss company that is rightfully considered a leader in the production of electrical products. Today, ABB circuit breakers are the highest quality, most durable and safe to use. As you understand, for such foreign products you will have to pay more money, than for the domestic model. At the same time, the difference in price is small, so for home and apartment we recommend buying machines from the manufacturer ABB.
- Legrand. Country of origin: France. Legrand circuit breakers are not inferior in quality to the ABB brand, so it is also preferable to choose Legrand products for electrical installation work. The cost of the machines is approximately the same, in fact, as in reliability.
- Schneider Electric. Another French company that closes the TOP 3 best manufacturer, specializing in the production of reliable circuit breakers. Schneider Electric has long been established in Russian market electrical products and has many positive feedback 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. Today there are many discussions on forums about which is better: GE or Legrand. Here we can say that both brands produce good quality circuit breakers, but in fact, Legrand is in greater demand in the Russian market.
- Siemens. The 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 slightly 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. A German company that successfully competes 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 is from such brands 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 approximately the same price and similar quality. Oddly enough, China provides a 5-year warranty on its products.
Our rating
So, we have listed all the most popular domestic and foreign companies that produce these devices. Now I would like to provide my own rating of circuit breaker manufacturers for 2019:
- ABB, in particular the S200 series. A detailed review of ABB machines is available at the link:. Slightly inferior to SH200.
- Legrand, TX3 or DX3 series.
- Schneider Electric, Acti9 iC or iK series. More a budget option Easy 9.
- Siemens, series 5SX, 5SY, 5SP, 5SL.
- General Electric, DMS LINE.
- Moeller, PL6 or PL7.
- Hager, MS series.
- KEAZ, OptiDin VM63.
- Eaton, xPole Home. By the way, we reviewed the machine from this series in a separate article: .
- DEKraft, VA-103.
The only thing I would like to clarify is that this rating of manufacturers of electric machines is not entirely convenient to base on it by company. Here you must first decide how much money you can allocate for home security automation. Even companies such as 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 Legrand, ABB and Schneider Eletric brands. For supporters of Russian products, we can recommend DEKraft, because... We haven’t come across a lot of negative reviews about this company on the forums!
That's all I wanted to tell you about companies specializing in the production of protective automation. We hope that you will make the right choice and use our rating of circuit breakers!
Related materials:
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 current parameters exceed the limits 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 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. The number of models of these devices from different manufacturers is 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 regulations, which 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 of operational characteristics of the 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 operating parameters. To achieve the desired result, it is necessary to carry out engineering calculations of all parameters so that the selection of a circuit breaker and other electrical devices ensures reliable and safe operation of the network. 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.
The trip class of domestically produced circuit breakers is designated 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, 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, an electromagnetic release reacts to current consumption, and thermal relay- for heating 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 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 strength luminous flux. Marking of circuit breakers much more complicated; a minimum of information can be squeezed into the product name. This is usually the rated 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 take into account that a copper wire with a cross-section of 4 mm, laid open method, can withstand a load of 9 kW. The same wire closed wiring 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 such a situation, preliminary calculations are necessary that 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 nominal value of the device according to bandwidth wiring (section and material of 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 the load on the network increases significantly (for example, installing an electric stove), you should not use old wiring. Selecting the correct circuit breaker for the load current will not help either, 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. At the everyday 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 amounts 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 the wiring and hidden defects in 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 safe operation 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.
Regular maintenance ensures that problems are identified early, prevents more serious consequences, and ensures that networks remain safe for the foreseeable future. Detected malfunctions of circuit breakers are eliminated whenever possible, but most often in such cases a complete replacement of electrical devices is required, 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 current consumers, taking into account installation conditions, wiring condition and other factors.
Our catalogs present a wide selection of 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 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.