Circuit breakers. Types, characteristics, calculation of the circuit breaker
The electrical network is a system that includes inputs, wires, current consumers, as well as switching equipment. Installing circuit breakers Provides network protection as a whole and individual consumers in emergency situations where the current parameters go beyond normal values \u200b\u200b(KZ, voltage jumps, changing the direction of current and so on). In addition, they allow you to fulfill infrequent commutation of consumers remotely or in manual mode (6-30 cycles of inclusion / disconnection per day).
Care of electric equipment
Evolution and fundamental device of circuit breakers
The history of the electric device began long before the emergence of the first commercial power grids. Thus, the principle of operation of the circuit breaker was opened back in 1836 by American scientist Ch. G. Paddage, but the modern design was patented only in 1924 by the Swiss company Brown, Boveri & Cie. Since then, each machine includes the following elements:
- contact block;
- neutralization chamber (arc) chamber;
- facilitator of the following types: thermal, electromagnetic, electronic, microprocessor;
- control mechanism: manual, spring or driven;
- the mechanism of free discharge.
Currently, a lot of electrical appliances are produced, what is the illustration of which serve characteristics of circuit breakersthat provide reliable switching and protection of power grids and consumers of any complexity and power in any operating conditions. The number of models of these devices of different manufacturers is not calculated.
Products of leading companies Siemens, Andeli, Schneider, whose products on the electrical engineering market are presented in the catalogs "Skat Technology" catalogs. Here you can see automatic switches in the photoand also 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 be obtained including in online mode.
For those who are interested in how the circuit breaker works, we will give a short explanation. Each machine has settings to certain current parameters and heating of conductors. These settings are provided by the sensitivity of the solenoid solenoid of the current and the thermal relay with screw control (calibration). If during the network of the network, the parameters go for the installed framework, the chain breaks and de-energize consumers.
Classification of circuit breakers
For the classification of electrical apparatus, there are regulatory documents in which the technical and operational requirements for them are set out. Classes of circuit breakers Domestic and foreign production are determined in accordance with such 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 documents, the classification of automata is carried out in 12 parameters that are taken into account dozens of operational characteristics of the devices. Quantitative and qualitative values \u200b\u200bof these parameters determine the purpose of the circuit breaker and the permissible conditions for its operation.
The main classification parameters of circuit breakers
The higher the level of the architecture of the power grid, the more difficult it is to select protection and management equipment to it, since you have to take into account a large number of different parameters of work. To achieve the desired result, it is necessary to carry out engineering calculations of all parameters so that the selection of the circuit breaker and other electrical apparatus ensures the reliable and secure operation of the network. The list of main characteristics of automata is as follows:
- nominal currents of the main chain and releasers -, respectively, 6.3-6300 (only 22 nominal) and 15-3,200 amps (only 12 denominations);
- constructive design - air or DC (800-6300 A), in a cast case or MCSB (10-2500 A), modular or MCV (0.5-125 A) automata;
- the number of poles of the main chain - from one to four;
- the presence or absence of current restrictions;
- types of release: zero, minimum, independent, maximum;
- presence or absence of contacts for connecting secondary chains;
- method for connecting input / conclusions: front, rear, combined, universal;
- mounting method: stationary, roll-out (on DIN rail), on connectors;
- type of cutoff: Normal, selective, instantaneous;
- type of drive: manual, spring, with propulsion (electromagnet, pneumatics, etc.);
- normal or secure execution.
The listed characteristics have their own designation or quantitative expression. For example, the shutdown curve of the circuit breaker is a graphical reflection of the reciphepter to the cut-off. It indicates with what the value of the nominal current "IN" is triggered the device. For this parameter, foreign production 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 triggering class of automatic switches of domestic production is denoted by letters B, C and D, since our industry does not produce the products of other types. In turn, the velocity of the cut-off automata is divided into normal (0.02-1 sec.) And high-speed or instantaneous (less than 0.005 seconds). Selectivity of circuit breakers Indicates the ability to establish different cut-off time with an excerpt 0.25-0.6 seconds for subordinate electrical apparatus.
The machines of this type have the main and additional work chains, which allows you to turn off the emergency plot of the power grid controlled by the subordinate apparatus, and keep the current supply to the remaining consumers. The time range of speed and selection processes also reflect curves circuit breakers. The operation of protection devices occurs not only by current, but also by heat of wires, which is provided by a thermal relay. Simply put, the electromagnetic release reacts to current consumption, and the thermal relay is to heat the wiring.
It is from the configuration of the last depends on the speaker characteristic of the circuit breaker. The thermal load value should not exceed the nominal value for the wires of a certain section by more than 1.45 times. It is determined taking into account the method of laying wires and a total load. Depending on the set setting, the thermal relay can work instantly or maintain a network performance for a certain time, but no more than an hour.
On the importance of timely response of protection equipment
From the above data, it is clear how important the operation time of the circuit breaker is. The minimum value of this indicator is necessary for powerful industrial equipment. Here you usually use the class D devices with instantaneous discharge. For domestic needs with a stock, there are enough machinery of a class C of normal discharge.
The exceptions make up worn networks and particularly sensitive current consumers where the Class A and B machines should be used, in which the minimum response time of the circuit breaker does not only provide protection, but also prevents the wiring fire. By the way, the state of the latter is often determining when choosing electrical equipment. If the wire section does not match the load on the network, the thermal characteristic of the operation of the circuit breaker will prevent its normal operation.
Reflection of the characteristics of electrical equipment in its marking
For electrical products, it is characteristic of the use of the most important performance in the marking of products. For lighting lamps, it is consumed power and light strength. Marking of circuit breakers It is much more complicated, in the name of the product you can squeeze the minimum of information. This is usually the nominal operating voltage. Therefore, the labeling symbols are applied to the vessel of the machine:
- the class of current restrictions is indicated by a number placed inside the square; The number of poles is displayed by an icon;
- the class or category of application of circuit breakers is displayed together with the value of the rated current - for example, "C16";
- the maximum permissible value of the operation current, at which the risk of damage to the machine is excluded in the rectangular frame.
The listed information in the product marking is enough to determine how to choose / select an automatic switch in full compliance with the power parameters. However, with independent acquisition of the device, it is easy to make a mistake, if you do not take into account the performance characteristics and load values. For example, the operating parameters of open and closed wiring, copper and aluminum wires differ significantly.
If you specify a question how to choose / select an automatic power switch, it should be borne in mind that the copper wire with a cross-section of 4 mm, laid by an open manner, withstands the load of 9 kW. The same wire with a closed wiring will withstand 5.9 kW. It is clear that the power of the current consumer should not exceed the possibility of wiring.
Similarly ratings of circuit breakers Must be less than the corresponding network parameters. Otherwise, the risk of overloading the power grid up to the ignition of the wiring, to which the automatic simplicity does not react. In order to avoid such a situation, preliminary calculations are needed, which will provide a balance between current consumers, wiring and means of protection and management. Those who are interested in the question how to choose a circuit breaker for home, We will give advice: the nominal value of the device choose the passage of the wiring (cross section and material of the wires, as well as the method of their gasket).
Basic rules for connecting the circuit breaker
The competent device of the architecture of the power grid allows for an order to increase their reliability. Currently, we use the mass of household appliances and technology, including having significant power. The old posting of the Soviet sample was not designed for such loads, so the consumers often arise a question how to calculate the current circuit breaker to ensure safe operation of the home power grid.
Based on the experience of its work, the company "Skat Technology" concluded that with a significant increase in the load on the network (for example, the installation of the electric stove) should not be used by the old wiring. It will not help the right choice of the circuit breaker for the current current, since the wiring is not calculated on it. It is best to fully reconstruct or replace the network with the distribution of current consumers by groups.
Electrical engineering - accurate applied science, so the production of electrical goods is performed according to certain standards. This is clearly seen by the example of what circuit breakers are, the design of which is designed for specific operating conditions. The separation of consumers into groups has long been practiced in industrial networks. At the household level, this approach looks like this:
- for lighting reinforcement, the nominal machine must not exceed 10 A;
- for conventional outlets - 16 A;
- for power outlets for electric stoves, boilers and other, the selection of the circuit breaker for the power of consumers is carried out.
To implement this approach to the network, manufacturers are offered a sufficient selection of automata with different amounts of poles, differential type and other aggregates. For household purposes, apparatuses in cast cases should be used, in which all current-host parts are protected, which eliminates random lesion to the current. In order to install a universal version of the universal switch, switchgear (cabinets, assembly, etc.) are required.
The variety of electrical apparatus is also explained by the fact that their design provides for all sorts of installation conditions. In other words, the device with identical parameters may have several versions. therefore connecting circuit circuit It is a mandatory application to each product. It indicates the number of poles, phase connection points and neutrals, methods for preparing the wires to connect and other features of a particular model.
If a person has a minimal idea of \u200b\u200belectrical engineering, it will not be in a long time to reveal how to connect a single-phase circuit breaker on the shield of its apartment. Just look at the scheme in which there is nothing complicated. Single warning: If you change the machine, in no case put the larger power switch than the previous one. First you need to make sure that the wiring is able to withstand an increased load.
Care of electric equipment
Electro appliances, like any other devices, needs to be care. Maintenance of circuit breakers is carried out according to a certain procedure with strict frequency. Users often do not suspect such a need, but it is. Electrical engineering is subject to wear, gradually occurs the oxidation of contacts, aging isolation, wear of movable parts and other changes. Therefore, the calculation of the circuit breaker for power, made 5 years ago, may not correspond to the real state of affairs.
Probably, many of you have occurred situations when the flawlessly working network starts to flure. The obvious manifestation of this becomes a fact when an automatic switch is often triggered without visible reasons. The reason may be in the device itself, but most often this happens due to problems with 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 performed in order to verify the compliance of the actual state of the automaton with the requirements of the safe operation of the power grid. The automatic circuit breakers verification technique provides for testing the insulation status, the protection time of protection on ultralox and heating, the status of contacts and other parameters.
Conducting regular maintenance ensures troubleshooting in the early stages, warns more serious consequences and guarantees the safe operation of networks in the foreseeable future. The detected malfunctions of circuit breakers are eliminated as possible, but most often in such cases requires a complete replacement of electrical apparatus, especially in the case of their small sizes.
Manufacturers of electrical products make many spare parts for powerful industrial machines. For household or low-power equipment, only spare contact groups are usually produced. therefore replacing circuit breakers - Typical effect when repairing the power grid. Regular cargo care is a completely ground-based procedure, including money. Its main goal is prevention.
Among the technical characteristics of the automata, also indicates the guaranteed number of inclusion cycles / disconnection. For these indicators, circuit breakers have a service life measured by decades, subject to the competent installation of devices and timely care. They must fully comply with network parameters. In addition, to extend the timing of their service, do not use faulty electrical appliances that provoke the frequent disabling network.
Professional services from the company "Skat Technology"
Our company specializes in the work on engineering communications, including power grids. Our specialists are ready to make recommendations on the selection of circuit breakers and perform network design, including load calculations and distribution them, taking into account all safety rates. Experienced engineers will answer any practical issues, including how to connect the circuit breaker For different categories of current consumers, taking into account the installation conditions, the state of the wiring and other factors.
Our catalogs present a wide selection of electrical products from leading manufacturers. Our range will allow, without much difficulty, to fully complete the work on the arrangement of the power grid. If you confuse cost of circuit breakers With the logos of famous brands, we remind you that high-quality products cannot be frankly cheap. In addition, the service life of such electric equipment is much higher than that of products of dubious origin.
Those who wonder what circuit breakers are better, you should define what's the point you invest in it. For us, the defining factor is the reliability and safety in adequate costs? We offer electrical products at the highest prices, so we are convinced that our buyers do not overpay. Dimensions of circuit breakers Not always are the equivalent of prices, so if you want to obtain a normal result of the electrical output, use the services of the "Skat Technology" professionals.
The electrical machine, or the circuit breaker, is a mechanical switching device, by means of which it is possible to manually de-energize the entire electrical outlet or its specific area. You can do this in the house, apartment, in the country, in the garage, etc. Moreover, such a device is equipped with the function of automatic shutdown of the electrical cable when emergenial situations occur: for example, in the event of a short circuit or overload. The difference of such circuit breakers from ordinary fuses is that after responding, you can turn on the button again.
Let's talk about how to choose automatic machines: electrical machines exist in a large manifold, which requires accounting for a number of a number of factors when purchasing them.
Do you need such a machine? It is necessary to give an affirmative answer. A working circuit breaker will protect your room from various unpleasant situations, including:
- fires;
- electric shocks;
- wiring damage.
So, when choosing a machine, as we noted, several indicators should be taken into account. Consider them in order.
Basic criteria for choosing
Short circuit current
This indicator must be considered immediately. It means that maximum current value at which the electrical machine will work and open the chain. Here the choice is not great, as there are only three options:
- 4.5 ka;
- 6 ka;
- 10K.
When choosing, you should be guided by theoretical probability of the occurrence of a strong short circuit current. If there is no such probability, it will be enough to purchase 4.5 cars.
Current machine
Accounting for this indicator is the next step. We are talking about the necessary nominal value of the operating current of the electrical machine. To determine the operating current, you need to be guided by the power that is supposed to be connected to the wiring, or by the valid current value (the level that will be maintained in normal mode).
What do you need to know when determining the parameter under consideration? It is not recommended to use automata with an overestimated operating current. Simply, in this case, the automatic during overload will not turn off the power, and this can cause thermal destruction of the insulation of the wiring.
This is perhaps the simplest indicator. To select the number of poles at the switch, you need to proceed from how it will apply.
So, a single pole machine is your choice if you need to protect the wiring, which goes out of the electrical panel to sockets and lighting chains.
The two-pole switch is used when it is necessary to protect all the wiring in an apartment or a house with single-phase power.
The protection of three-phase wiring and load is provided by a three-pole automatic machine, and the four-pole are used in order to protect the four-wire power supply.
Characteristics of automatic
This is the last indicator to be needed to pay attention. The time-current characteristic of the circuit breaker is determined by the loads that are connected to the protected line. When choosing, the characteristic is taken into account: the operating current of the chain, the rated current of the machine gun, the cable bandwidth, the operating current of the switch.
- In the event that it is necessary to connect small launchers to the power line, i.e. Electrical devices characterized by a small difference between the operating current and the current, which occurs when turned on, preference should be given to the response characteristic of B.
- Finally, there is another characteristic - D. Your choice should be stopped on it if you are supposed to connect powerful devices with high startpoints. What devices are we talking about? For example, about the electric motor.
The final stage of choice
These are the main indicators that should be considered when choosing an automatic switch. Accordingly, if all the necessary data you will be known, the choice will not be difficult. It will only be taken into account the latest criterion - manufacturer of the machine. What does it affect?
- obviously, the cost. Indeed, there is a difference. Thus, the well-known European brands offer their circuit breakers at a price, which is twice the cost of domestic analogues and three times the price of instruments from southeastern countries;
- also, the choice of a specific manufacturer depends on the presence of either the absence of a switch with well-defined indicators in the warehouse.
Another useful way to choose an electrical machine is offered on the video below:
The main difference between these switching apparatuses from all other similar devices is a comprehensive combination of abilities:
1. Long maintain nominal loads in the system due to reliable transmission through its contacts of powerful electricity flows;
2. Protect the working equipment from accidentally emerging faults in the electrical circuit due to the rapid removal of power from it.
Under normal operating conditions, the operator can manually switch the load with automatic switches, providing:
different power schemes;
changing network configuration;
conclusion of equipment from work.
Emergency situations in electrical systems occur instantly and spontaneously. A person is not able to quickly react to their appearance and take measures to eliminate. This feature is covered with automatic devices embedded in the switch.
In the energy sector, it is customary to divide electrical systems by type of current:
constant;
variable sinusoidal.
In addition, there is a classification of equipment for the magnitude of the voltage on:
low-voltage - less than thousands of volts;
high-voltage - everything else.
For all types of these systems, their circuit breakers are created for multiple work.
Chains of alternating current
By power transmitted electricity, the circuit breakers in the AC circuits are conditionally divided into:
1. Modular;
2. in the cast case;
3. Power air.
Modular structures
Specific performance in the form of small standard modules with a width of multiple 17.5 mm determines their name and design with the possibility of installing on a DIN rail.
The internal device of one of the similar circuit breakers is shown in the picture. Its housing is fully manufactured from a durable dielectric material excluding.
The feed and exhaust wires are connected to the upper and lower terminal clamp, respectively. For manual control of the switch, a lever with two fixed positions is installed:
the top is designed to supply current through a closed force contact;
lower - ensures the break of the power chain.
Each of such automata is designed for long-term operation at a certain value (IU). If the load becomes larger, then the power contact occurs. For this inside the case there are two types of protection:
1. thermal release;
2. Current cutoff.
The principle of their work allows you to explain the spectacular characteristic, expressing the dependence of the time of the protection of the protection against the current or accident passing through it.
The graph presented in the picture is given for one particular circuit breaker, when the cut-off area is selected in 5 ÷ 10 times the nominal current.
When initial overload operates a heat release, made of, which, with an enlarged current, gradually heats up, bends and affects the disabled mechanism not immediately, but with a certain time delay.
In this way, it allows small overloads associated with a short-term connection of consumers, it is expected and eliminating unnecessary shutdowns. If the load will ensure the critical heating of the wiring and isolation, then the power contact occurs.
When an emergency current occurs in the protected chain, which can burn the equipment with its energy, the electromagnetic coil comes into operation. It impulse at the expense of the load of the load throws the core to the disconnecting mechanism in order to instantly stop the exhaust mode.
The graph shows that the higher the currents of short circuits, the faster there is a shutdown by an electromagnetic release.
On the same principles, the household fuse is automatic steam.
When the high current breaks, an electric arc is created, the energy of which can burn contacts. To exclude its action in circuit breakers, an extinguishing chamber is used, separating arc discharge on small streams and quenching them by cooling.
Multiplicity of cutoffs of modular structures
Electromagnetic releasers are configured and selected under work with certain loads because when starting, they create different transient processes. For example, during the inclusion of different lamps, a short-term flow of current due to the changing resistance of the filament may approach the three crown of the nominal value.
Therefore, for the outlet group of apartments and lighting chains, it is customary to select automatic switches with a streaming characteristic of the "B" type. It is 3 ÷ 5 IN.
Asynchronous motors when promoting a rotor with a drive causes large overload currents. For them, machine guns are selected with the characteristic "C", or - 5 ÷ 10 IU. Due to the reserves of time and current, they allow the engine to spin and guarantee the operating mode without excessive shutdowns.
In industrial production on machines and mechanisms, loaded drives connected to engines that create more enlarged overloads are found. For such purposes, the automatic switches of the characteristics "D" are used with a par value of 10 ÷ 20 IU. They have proven themselves well when working in schemes with active inductive loads.
In addition, automata has three more types of standard time characteristics that are used for special purposes:
1. "A" - in long wiring with active load or protection of semiconductor devices with a value of 2 ÷ 3 IU;
2. "K" - for pronounced inductive loads;
3. "Z" - in electronic devices.
In technical documentation, different manufacturers have multiplicity of cut-off for the last two types may differ slightly.
This class of devices can switch large currents than modular designs. Their load can reach up to 3.2 kiloamum.
They are manufactured according to the same principles as modular designs, but, taking into account the increased requirements for passing an increased load, they are trying to give relatively small dimensions and high technical quality.
These automata are designed to safely work at industrial facilities. According to 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 amps.
Constructive execution of their hull: three- or four-pole models.
Power switches
They operate in industrial installations and operate with currents of very large loads up to 6.3 kiloampers.
These are the most complex devices of low-voltage equipment. They are used to work and protect electrical systems as introductory and exhausting devices for enhanced power distribution settings and to connect generators, transformers, capacitors or powerful electric motors.
A schematic image of their internal device is shown in the picture.
It uses already a double power supply breaking and exhaust cameras are installed with grilles on each side of the shutdown.
In the work algorithm, the inclusion coil, a closing spring, a springs platform motor and automation elements. To control the flowing loads, a current transformer with a protective and measuring winding is built.
The automatic switches of high-voltage equipment belong to very complex technical devices and are made strictly individually for each class of voltage. They are used, as a rule.
These are presented:
high reliability;
security;
speed;
ease of use;
relative silent when working;
optimal cost.
Loads that are torn during emergency disabling are accompanied by a very strong arc. It uses various methods, including a chain gap in a special environment.
This switch includes:
contact system;
exhausting device;
current parts;
isolated case;
drive mechanism.
One of these switching devices is shown in the photo.
For high-quality operation of the scheme in such structures, except for the operating voltage, take into account:
the nominal value of the load current for reliable transmission in the on state;
the maximum short circuit current on the valid value, which is able to withstand the disconnecting mechanism;
the permissible component of the aperiodic current at the time of the division of the scheme;
opportunities for automatic re-inclusion and provision of two CPV cycles.
According to arc harvesting methods during disconnection, the switches are classified on:
oil;
vacuum;
air;
elegazovy;
autogas;
electromagnetic;
autoinnevatic.
For reliable and convenient operation, they are supplied with a drive mechanism, which can use one or more types of energies or combinations:
sprout;
raised cargo;
compressed air pressure;
solenoid electromagnetic pulse.
Depending on the conditions of application, they can be created with the ability to work under voltage from one to 750 kilovolt inclusive. Naturally, they have a different design. Dimensions, automatic and remote control capabilities, protection defense for safe operation.
Auxiliary systems of such circuit breakers may have a very complex branched structure and placed on additional panels in special technical buildings.
DC circuits
These networks also work a huge number of circuit breakers with different capabilities.
Electrical equipment up to 1000 volts
Here we are massively introduced modern modular devices that have the ability to mount on a DIN rail.
They successfully complement the classes of old machines of type, ae and other similar, which were fixed on the walls of the shields with screw connections.
Modular DC designs have the same device and principle of operation, as their analogues on alternating voltage. They can be performed by one or more blocks and are selected by load.
Electrical equipment above 1000 volts
High-voltage circuit breakers for DC are operated on the installations of electrolysis production, metallurgical industrial facilities, railway and urban electrified transport, energy enterprises.
The main technical requirements for the operation of such devices correspond to their analogues on alternating current.
Hybrid switch
Scientists of the Swedish-Swiss company ABB managed to develop a high-voltage DC switch, combining two power structures in its device:
1. Elegazine;
2. Vacuum.
It was called a hybrid (HVDC) and uses the technology of consistent arc cleaning immediately in two environments: sulfur hexafluoride and vacuum. For this, the following device is collected.
A voltage is supplied to the top tire of the hybrid vacuum switch, and from the lower tire of the Elegazovoy - removed.
The strengths of both switching devices are connected sequentially and managed by their individual drives. In order for them at the same time, a synchronized coordinate operation management device is created, which transmits the command to the control mechanism with independent power to the fiber optic channel.
Due to the use of high-precision technologies, construction developers managed to achieve consistency of the actions of the actuators of both drives, which is laid in a period of less than one microsecond.
The switch control comes from the relay protection unit built through the repeater in the power line.
The hybrid switch made it possible to significantly increase the efficiency of composite email and vacuum structures through the use of their joint characteristics. It was possible to realize the benefits of other analogues:
1. The ability to reliably turn off the currents of the KZ with high-voltage voltage;
2. The possibility of a small effort to carry out the switches of power elements, which made it possible to significantly reduce the dimensions and. Accordingly, the cost of equipment;
3. Availability of the execution of various standards for creating structures operating in a separate switch or compact devices on one substation;
4. The ability to eliminate the consequences of a rapidly increasing regenerating voltage;
5. The ability to form a basic module to work with voltages to 145 kilovolts and above.
A distinctive feature line is the ability to break the electrical chain for 5 milliseconds, which is practically impossible to perform other structures with power devices.
The hybrid switching device is marked among the ten best developments for the year according to the MTI Technological Review (Massachusetts Institute of Technology).
Other manufacturers of electrical equipment are engaged in similar studies. They also achieved certain results. But ABB is ahead of them in this matter. Its guide believes that when transmitting the electricity of the AC, its large losses occur. They can be significantly reduced using high-voltage voltage chains.
Surely, many of us thought, why the circuit breakers so promptly displaced out of the power supply outdated fuses? The activity of their implementation is justified by a number of very convincing arguments, among which the opportunity to buy this type of protection, ideally corresponding to the time-current data of specific types of electrical equipment.
Doubt what kind of machine you need and do not know how to choose it right? We will help you find a right decision - the article considers the classification of these devices. As well as important characteristics for which close attention should be paid when choosing an automatic switch.
To make it easier for you to deal with machine guns, the article of the article is supplemented with visual photos and useful video reconditions from specialists.
The machine gun almost instantly turns off the line entrusted to him, which eliminates the damage to the wiring and eating from the vehicle. After completing the disconnection, the branch can be immediately launched immediately without replacing the safety instrument.
If you have knowledge or experience of electrical work, please share it with our readers. Leave your comments on the selection of the circuit breaker and the nuances of its installation in the comments below.
Automatic switches Not at all similar to the usual, which are installed in each room to turn on and off the light (Fig. 1). Their task is somewhat different. The circuit breakers are installed in switchboards and serve to protect the chain from voltage jumps and non-periodically disconnecting energy at certain sections of the power grid.
Fig. one.
MachinesAs they are more often called, installed at the entrance to the house or apartment and are located in special boxes, metal or plastic (Fig. 2).
Fig. 2. Distribution shield with automata
There are many varieties of circuit breakers. Some of them serve only as circuit switches and overload protection. Such, for example, old aU circuit breakers In a black carbolite case (Fig. 3).
Fig. 3. AE series circuit breaker
In most old plates in the entrances of residential buildings, it is precisely such. However, they are quite reliable and operated so far.
Modern variations admit additional functions, such as protection against reduced load currents.
By time of response to an invalid voltage, the automata is divided into 3 species: selective, normal and high-speed. The response time of a normal automaton varies from 0.02 to 0.1 s. In selective circuit breakers, this time is the same. High-speed circuit breakers work more higher - they have a given value of 0.005 s.
All circuit breakers are enclosed in a plastic unbating case with a special mount (bar or rail) on the rear plane. Installing the machine on such a mount is very easy - it is enough to insert it on the rail until it clicks. You can remove with a screwdriver, slightly pulling the special ear in the top of the circuit breaker. This significantly facilitates the task of installing the automaton in the cabinet (Fig. 4).
Fig. four.
Inside the case there is a "filling" of the machine, its main safety devices, which can be 2 (Fig. 5).
Fig. 5. Internal
We are talking about electromagnetic and thermal releases - peculiar mechanisms of automatic interruption of the chain. The bimetallic plate when heated by the current passing through it is unacceptably the high value straightens and the contacts will be blurred - this is a heat release. By time of response, he is the slowest.
The electromagnetic release works according to the rule of the "dead hand". The coil located in the center of the machine is continuously maintained in place by stable voltage. It is worth it to jump over the nominal limits, as the coil literally pops up from his seat, breaking the chain. This method of breaking the chain is the fastest.
All circuit breakers have contacts to attach suitable and outgoing wires (Fig. 6).
Fig. 6. Wires are connected to the contacts of the circuit breaker using screw clamps
Machines are distinguished according to the degree of sensitivity to trigger shutdown. In the standard most common models, automatic switches with a threshold value are most often used, approximately 140% of the nominal. With increasing voltage, one and a half times the electromagnetic (fast) release is trimmed. With a minor exceeding the nominal voltage, a thermal release is operating. The disconnection process can stretch to hours, which is highly dependent on the temperature of the external environment. However, the machine will react to the voltage change in any case.
Circuit breakers are distinguished by the number of poles. What does it mean? In one machine, there may be several electrical lines independent of each other, which are interconnected by a common shutdown mechanism (Fig. 7 and 8). Machines are single, two, three- and four-pole (this concerns domestic use).
Fig. 7. In the plastic box in the off state
Fig. 8.: All lines are triggered simultaneously when disabling, they are connected together using one lever jumper
The circuit breaker has differences on other indicators. They differ in the threshold strength of the current, which they pass through itself. So that the machine can work and turn off the power grid in an emergency, it must be configured to a specific sensitivity threshold. This setting manufactures the manufacturer, so the numeric value of this threshold immediately writes on the machine. For household needs, automata with indicators 6.3, 10, 16, 25, 32, 40, 63, 100, and 160 A are used (Fig. 9). There are automata with values \u200b\u200band 1000, and 2600 A, but in everyday life they are not used. These figures mean the total power of all consumers of the electric current that will be connected to the chain, "protected" machine.
Sensitivity machine gun It is necessary to calculate not only in the total power of the alleged energy consumers, but also the wiring, and electrical installation products - sockets and switches.
Table 1 presents the typology of automata.
Table 1. Types of automata
| A type | Purpose |
| A. | Circuits for chains with high extension of electrical wiring and protecting conduction devices |
| B. | General Purpose Sewing Networks |
| C. | Ensitive chains and electrical installations with moderate starting currents (engines and transformers) |
| D. | Short-circuits with active inductive load, as well as electric motors protection with large starting currents |
| K. | For inductive loads |
| Z. | For electronic devices |
Table 2. Two-room padded copper cable
| Section, mm2 | Cable strength / 1.45, and | Automatic, A. | Excess current strength,% | |
| 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-tire laid in the box copper wire
| Section, mm2 | Maximum prolonged cable current, and | Cable strength / 1.45, and | Automatic, A. | Excess current strength,% |
| 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 long cable current is accepted for the temperature of the veins +65 and air +25 ° C. The number of simultaneously paved conductors - to 4. A row of automata: 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 Suitable for a three-core cable. In this case, the third lived should be a wire of protective grounding or reassembly.
Fig. 9. A number of single-pole machines on 16 A. Suppose, for a separate plot in the apartment, for example, the kitchen, we have one automatic on 6.3 A (it happens - electricians joked). According to the well-known Watt formula \u003d Volt X Ampere calculate how many instruments (and which) can be powered by our network. It turns out that this value is 1386 W, since the default voltage is 220V. It means that even a powerful teapot cannot be included in such a kitchen, not to mention the refrigerator or electric stove - the machine will work instantly and will not give an unacceptable, in his opinion, to pass on Controlled territory. In this case, it is necessary to urgently change the circuit breaker by 25 or even 32 A.
