Connecting a circuit breaker - how to do it yourself. Detailed instructions on how to connect a circuit breaker Rule for connecting a circuit breaker

Content:

Circuit breakers, called automata or switches in everyday life, refer to the means of switching and are intended to supply electric current to an object. The main function of these devices is to automatically turn off the power supply in the event of an emergency and network problems. The machine protects the electrical circuit from short circuits, overloads and voltage drops beyond the permissible value.

In old houses, in the power supply system, the neutral wire was not only a working one, but also performed a protective function at the same time. In modern buildings, a clear separation of the purpose of working and protective conductors is provided. In this regard, the question often arises of how to connect a circuit breaker, since all European-style electrical installation products are equipped with terminals for connecting a ground wire. In addition, the fastening of the machines themselves in the switch cabinet can be done by mounting on a DIN rail or on a special mounting panel.

Device and principle of operation

Before connecting the machine, it is necessary to understand the features of its design and the principle of operation. The circuit breaker consists of a housing, a switching device, a control mechanism in the form of a button or a handle, an arc chute and screw terminals located at the top and bottom.

For the manufacture of the body and the control mechanism, durable plastic is used that does not support combustion. The switching device consists of moving and fixed contacts. Each pole of the machine consists of a pair of these contacts and is equipped with its own arc chute.

The purpose of the arc chute is to extinguish the electric arc that appears when the contacts are broken under the action of the load. The chamber itself is made in the form of a set of steel plates with a profile of a certain shape. They are isolated from each other and located at the same distance relative to each other. It is to these plates that the arc is attracted, which here cools down and dies out. The number of pairs of contacts in different models of machines ranges from 1 to 4. The devices have position indicators. Red indicates on, green indicates off. In this way, the current state of the circuit breaker can be determined very quickly.

All parts are hidden inside the case, only the upper and lower screw clamps, control handle and indicator are visible from the outside. There is a latch on the case that allows you to quickly install the machine on and just as easy to dismantle it.

To turn off the machine, there is a special mechanism called a release. Each type of release has its own design. For example, in conventional machines, the function of a disconnecting device is performed by a coil with a winding and a core. For winding, copper insulated wire is used. The inclusion of the coil in the electrical circuit is carried out in series with the contacts, since it is through it that the load current moves. If this current exceeds the set permissible value, then under the influence of the magnetic field of the coil, the core moves and has a mechanical effect on the disconnecting device. As a result, the contacts of the circuit breaker open.

The design of the thermal release has its own characteristics. It includes a special bimetallic plate. For its manufacture, two types of metals are used, heterogeneous in composition and with different coefficients of linear expansion. The plate is connected to the circuit in series with the load. During the operation of the machine, it is heated by the current passing through it. In case of overload, the plate bends towards the metal with the lowest expansion coefficient. The trigger mechanism comes into action, turning off the machine. The greater the current exceeds the rated value, the faster the thermal release trips.

Installation of circuit breakers

The connection of circuit breakers in the switch cabinet is carried out in a certain sequence. From above, a cable is connected to an external current source, and through the output holes located below, the wiring is routed to its objects, in accordance with the electrical circuit.

At the beginning of the installation, an introductory machine is connected. If there are several lines in the circuit that are isolated from each other, they are separated from the introductory circuit breaker. Its power must not be less than the total power of the machines connected to separate lines. For this purpose, two- or four-pole devices of group D are selected that are resistant to the inclusion of power tools and other powerful equipment.

The most widely used, suitable for any power supply schemes for apartments and private houses. Modular circuit breakers are mounted on a DIN rail and connected by conductors with a current carrying capacity exceeding the operating current of the circuit breaker. A more convenient connection of several machines in one row can be performed using a special connecting bus. A piece of the required length is cut off from it and fixed in the terminals. Such a connection is possible due to the distance between the bus contacts, corresponding to the standard width of the modular machines. The switch is installed on the phase, and the neutral conductor is supplied from the input device directly to the devices.

single pole the switch is used in the installation of sockets and lighting systems.
Bipolar the machine is suitable for high power appliances, such as an electric stove or a boiler. In case of overloads, it is guaranteed to break the circuit. The connection diagram of such switches is practically no different from single-pole models. For more efficient use, it is recommended to connect them to a separate line.
Three-pole the circuit breaker should be installed only in cases where it is planned to use electrical appliances operating at a voltage of 380 V. In order to exclude, the load is connected according to the "triangle" scheme. This connection does not require a neutral conductor, and the consumer is connected to his own switch.
four-pole the circuit breaker is most often used as an input. The main condition for connection is the uniform distribution of the load on all phases. When connecting equipment according to the “star” scheme or three separate single-phase wires, excess current will flow through the neutral conductor.

With a uniform distribution of all loads, the neutral wire begins to perform a protective function in case of unforeseen power imbalances. To ensure a normal connection, only high-quality materials should be used. All connections must be securely fastened to the terminals. If several cables are connected at once, their contacts must be carefully cleaned and tinned.

The procedure during connection can be considered using the example of a two-pole circuit breaker installed in a shield. First of all, the electricity is turned off in order to completely de-energize the network. The absence of electricity is checked with an indicator screwdriver or a multimeter. Then the machine must be installed on a DIN rail and snapped into place. The absence of a mounting rail can create certain inconveniences. After that, the cores of the incoming and outgoing wires are cleaned to a distance of 8-10 mm.

Introductory wires are connected to two clamps located on top -. In the lower clamps, similar outgoing conductors are fixed, distributed to sockets, switches and electrical appliances. All wires are qualitatively clamped in the terminals with screws. The connections must be checked manually. To do this, the conductors must be gently moved from side to side. In the event of a poor-quality connection, the core will stagger in the terminal and may even jump out of it. In this case, the terminal screw must be tightened.

Upon completion of installation, voltage is applied to the network and the operability of the circuit breaker is checked.

How to choose the right machine

The correct choice of the circuit breaker is of great importance. Each device has its own parameters, such as rated current, network operating voltage, number of poles, maximum short-circuit current, time-current characteristic and other important values.

The operating time of the device has a digital designation indicating at what current the normal operation of the circuit breaker is maintained. In home electrical networks, machines with numbers 4500, 6000 and 10000 amperes are most often used. All technical characteristics are indicated by manufacturers directly on the device case. This also includes the connection diagram, as well as the symbol of the machine.

The main criteria for choosing a circuit breaker is the load power and the cross section of the wires used. In addition, the overload current and short-circuit breaking current are taken into account. As a rule, overloads in the network occur when devices and devices with a total power are turned on at the same time, causing excessive heating of conductors and contacts. Therefore, the tripping current of the machine installed in the circuit must be greater than or equal to the calculated one. Its value is defined as the sum of the capacities of all devices used, divided by 220.

The short-circuit tripping current also causes the machine to trip. It is selected by calculation for a specific circuit and depends on the loads used most often. In order to improve protection, they can be included in the electrical circuit.

Errors when installing the circuit breaker

When performing electrical work, serious mistakes are sometimes made that can lead to negative consequences in the course of further operation.

The power cable is connected from below. Although this is not prohibited by the PUE, such a scheme will be inconvenient, since the installation and placement of machines in the shield is designed specifically for the top connection.
A common mistake is to over-tighten the pins with the set screws. This can lead not only to damage to the core, but also to deformation of the body of the product.
Sometimes the wires are connected incorrectly. It is necessary to pay attention to the marking, connect the phase and neutral wires located on top with the same wires located below.
In some cases, one two-pole machine is replaced by two single-pole ones. This is absolutely impossible to do, since they do not provide simultaneous separation of the phase and zero.
Often, during the fixation of the core in contact, the insulation enters the seat. This leads to a weakening of the contact, resulting in overheating of the core and other negative consequences. Therefore, it is imperative to protect the wire in accordance with the technical requirements of a particular model of the machine. This operation must be carried out using a stripping tool.

A negative role can be played by the wrong choice of the circuit breaker, which subsequently is not able to withstand the planned loads. Therefore, it is recommended that you first perform all the necessary calculations, especially. It should be remembered that when calculating the value of the automaton should be rounded down. For example, with a current load of 20 A, the circuit breaker should be selected at 16 A, which will significantly increase the life of the wiring.

The most common means of protecting the line and electrical appliances are circuit breakers. When installing them, you must follow the basic rules.

Input at the top of the machine, output at the bottom.
The enable flag should be directed upwards when the machine is turned on.
There should be no exposed wires.

How to connect a differential machine

The differential machine combines protection of the line from overloads and short circuits, as well as automatic switches, and protection of a person from electric shock as an RCD.

The case version does not differ from automata or RCDs, which makes it possible to install a differential automaton in standard boxes using a DIN rail.

Connecting a differential machine also resembles connecting a circuit breaker, with a small exception - two rules must be observed.

It is necessary to observe the phasing of the connected wires. On the case of the differential machine, the designations of the zero and phase input are applied, which must be taken into account during installation.
The neutral wire connected at the output of the differential machine is used only with the line that the device protects.

Differential automata are very reliable and unpretentious, but deviation from these rules does not guarantee the correct operation of the device.

For a single-phase network, the use of two-pole machines is preferable to single-pole ones. The reason is simple - when voltage appears on the neutral wire, with one movement of the flag, the circuit is completely broken, saving both the line and the electrical appliances connected to it. The housing version of the two-pole switch allows mounting on a standard DIN rail.

In this case, it should be borne in mind that the width of such an automaton is larger, as a rule, twice as much as a single-pole automaton. The upper contact pair is designed to connect the phase and neutral wires.

There are no strict rules for the location of the phase and neutral wires, but in the case of connecting a number of two-pole machines, it is necessary to follow the same tactics.

Having chosen, for example, the left contact for the phase wire, all other machines must be connected as well. The left contact is phase, the right contact is zero.

The stripped wires are fixed in the contacts using screw clamps. In this case, there should be no bare sections of the wire. Do not forget that there is a very small distance from the phase to the neutral wire and there is a possibility of a short circuit in the absence of insulation.

The most commonly used single-pole circuit breakers are reliable, easy to install and provide the necessary line protection against overloads and short circuits.

When connecting the circuit breaker, it is important that the body of the machine is securely fastened and, when turned on - turned off, does not fall off the attachment point.

To do this, use a mounting DIN rail or special boxes with pre-installed rails in the housing. The machine is mounted on a rail using a spring-loaded latch at the bottom of the case.

After installing the machine, a wire is connected to it. The top terminal of the machine is responsible for the input voltage, and the lower terminal is for the output. The wires laid and fixed on the wall are brought to the machine and cleaned.

In this case, be sure to observe the condition of the integrity of the insulation everywhere, except for the terminal blocks. The length of the stripped ends is quite enough at 1-1.5 cm.

The phase incoming and outgoing wire is clamped in the terminals of the machine, while the zero one can pass through the box or, if necessary, is fixed on the neutral rail.

Incoming and outgoing wires must be laid in such a way as to avoid excess length. The wires are laid parallel to each other and, if possible, all bends are made at right angles.

After installing the machine and checking all connections, the first switch-on must be carried out without a connected load on the line.

Greetings, dear readers of the site.

In continuation of a series of publications on circuit breakers, the next article in the cycle - circuit breaker connection diagram.

Let me remind you that a series of articles is included in the course.

We have already studied in detail the design and main technical characteristics of the machines, let's look at their connection diagrams.

Depending on the number of switched poles (or otherwise modules), the machines are divided into one-, two-, three-, four-pole (three phases and zero). In the event of an emergency, all poles of the circuit breaker are switched off at the same time.

One pole is a part of the machine, which includes two screw terminals for connecting wires (on the supply side and on the load side). The width of a single-pole circuit breaker mounted on a DIN rail is standard - 17.5 mm, multi-pole circuit breakers are a multiple of this width.

One- and two-pole are used in a single-phase electrical network. Most often, single-pole automata are used, they are installed in a break in the phase wire and, in the event of an emergency, disconnect the supply phase from the load.

Bipolar automata allow you to simultaneously turn off both zero and phase. They are most often used as introductory machines, or if it is necessary to completely disconnect the consumer from the electrical network, for example, a boiler, a shower cabin. They disconnect zero and phase from the protected section of the circuit and allow repair, maintenance or replacement of circuit breakers.

You cannot install two single-pole circuit breakers separately to protect the phase and neutral wires. For these purposes, bipolar automata are used, which turn off zero and phase at the same time.

Three- and four-pole are used in a three-phase electrical network. Three-pole circuit breakers are installed in a phase break (L1,L2,L3) of a three-phase network and are used to connect a three-phase load to it (electric motors, three-phase electric stoves, etc.). In the event of an emergency, they disconnect simultaneously all three phases from the load.

Four-pole machines allow you to simultaneously turn off both zero and all three phases, and are used as introductory machines in a three-phase electrical network.

Allows you to turn off all the electrical wiring of the apartment and disconnect the supply line from the group electrical circuits of the apartment.

Depending on the grounding system, the following input machines are used:

The introductory machine for the TN-S system (where the zero working N and zero protective PE conductors are separated) must be:

- single-pole with zero or two-pole;

- three-pole with neutral or four-pole.

The TN-S system is used in modern homes.

This is necessary to simultaneously disconnect the apartment's power supply from the zero working and phase conductors from the side of the power supply input, since the neutral and protective conductors are separated throughout.

For the TN-C system (where the zero working and zero protective conductors are combined into one PEN conductor), the introductory circuit breaker is installed single-pole (with 220 V power supply) or three-pole (with 380 V power supply). They are installed in the gap of the phase working conductors.

The TN-C system is used in Soviet-built houses (the so-called "two-wire").

According to the rules for the installation of electrical installations (clause 1.7.145), it is not allowed to turn on switching devices in the circuits of PE- and PEN-conductors, with the exception of cases of power supply to electrical receivers using plug connectors.

This requirement of the PUE is due to the fact that a situation is possible when two-pole circuit breakers cannot simultaneously turn off the phase and PEN conductors. And by disconnecting the PEN conductor, we thereby initiate its breakage.

When switched on under load, sticking or phase contacts may occur inside the machine (for example, a grain of sand may get on the contact group of the machine), in this case, when the machine is disconnected from the mains, the PEN conductor will break and a dangerous potential will be carried out to the zeroed electrical equipment cases. Those. there is no guarantee that the switching devices will simultaneously disconnect both the phase and PEN conductors.

Connection of wires to circuit breakers is carried out according to the scheme: "supply from above", and "load from below". Those. the wire with the supply voltage is connected to the upper screw terminal, and the outgoing load wire to the lower screw terminal.

See detailed video Connection diagrams for circuit breakers

We examined the design, main characteristics, connection diagrams of circuit breakers and came close to the issue of their choice.

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Before proceeding with the installation of circuit breakers, it is necessary to determine the operating conditions of the electrical network with its characteristics:

By current;
By voltage;
The electrical power of the appliances that will be connected as a load.

The type and characteristics of the selected circuit breaker depend on this, respectively, the methods of its installation and connection.

Purpose and scope of circuit breakers

Circuit breakers are the control elements of the switching system, they perform three main functions:

Ordinary switch, on and off;
Disconnection of the load from the network when the set current threshold is sharply exceeded, this happens when there is a short circuit in the circuit or a malfunction of the load equipment;
Some circuit breakers trip when there is a sharp drop in current when appliances that consume a large amount of electricity are turned on. To eliminate malfunctions on expensive equipment with large voltage and current surges in the network, the machines turn off the load.

All these machines have different technical characteristics, design features.

The main types of circuit breakers

Manufacturers make a lot of varieties of different models, despite their design differences.

Appearance of various types of circuit breakers
They all work on the same principle and are designed for the same purpose. When the set current threshold is exceeded, they disconnect the circuit from the power source to save the equipment from overloads.

By purpose, circuit breakers can be divided into the following types:

For switching equipment in lighting, socket networks, power lines with household equipment of low power;
For switching power supply to electrical installations that are operated in extreme conditions, in an explosive environment, high humidity or dust;
For multiple switching of semiconductor devices in various electronic systems.

According to their design features, they are divided into three main types:

Air circuit breakers have openings in the body structure through which the elements inside are ventilated. Such models are used in normal dry operating conditions, without fumes and dust;
Molded case switches are used in extreme operating conditions;

Modular switches are one of the options for air, the design feature is that their dimensions and mounting mechanism are standardized.

The latter option is the most popular among consumers at the domestic and industrial level. The reason for such popularity is the versatility of these models, ease of installation and connection. Therefore, we will consider in detail how these circuit breakers are connected.

Characteristics and selection criteria of the modular circuit breaker

When choosing a modular circuit breaker, the following characteristics must first be considered:

Maximum breaking capacity measured in kA (kiloAmperes) - this is the amount of current at which the machine still remains operational. The minimum value of this parameter on industrial and domestic networks is from 3 kA to 10 kA;
Time - current characteristic, sometimes this value is called the sensitivity of the circuit breaker to current overloads.

By sensitivity, the switches have three classes, B - the machine is turned off when the rated current is 3-5 times higher for a certain section of the network. C - 5-10 times and D 10 - 20 times, when operating equipment with electric motors, the group B option is not recommended, short-term starting currents can cause unreasonable, frequent trips. C is considered a universal option, for electric motors D.

Rated current section of the network, when a shutdown occurs, switches are made with values in the range of 0.5 - 125 A for modular designs. For industrial introductory circuit breakers, this value can reach thousands of amperes.
Number of poles on the switch can be from 1 to 4. The width of the housing of a single module, depending on the series of the product, is 18mm, the compact version is half less than 9mm, the extended version is 27mm.

Given these parameters, the choice of switches is made for a specific section of the network, after which a diagram of their connection is drawn up or studied.

Connection diagrams for circuit breakers

The classic option is to include automatic modular switches in the network diagram when they are placed in the switchboard. Fastening is carried out on a factory din - rail located horizontally inside the shield. In the space between the rail and the rear wall of the cabinet, wires leading to the load are inserted. They are connected to the lower output contacts of the machines, to the input, upper contacts, the wire from the output of the introductory machine is turned on.

On the back wall of the machine, a channel is made under the rail, the upper face of the case clings to the rail and by pressing on the front plane of the case, the lever with the spring fixes the lower part of the case to the rail. The machine is removed from the rail in the reverse order, the lever is pulled back, the lower part of the body is retracted, lifting it up, so the entire body is removed from the rail.

Advice No. 1 Introductory circuit breakers of high power, not equipped with a DIN rail mount, are separately mounted on a metal plate installed in the shield with holes and threads for bolts. Holes in the body of the machine for fastening to the body of the shield are provided by the design, you can use self-tapping screws for metal.

Single-pole machines

The connection of single-pole machines is considered the simplest; they are connected to socket and lighting groups.

Two-pole machines

More powerful devices, such as electric stoves, heating boilers, shower cabins, split systems and others, where it is necessary to ensure a complete circuit break, neutral and phase wires are connected through bipolar devices.

Three-pole machines are used in three-phase networks using powerful devices with an appropriate power supply of 380V. It can be heating elements, electric motors and others. When, when the rated current is exceeded, all three phases are disconnected, thus eliminating phase imbalance in the entire circuit when the current is exceeded in one of the three lines.

Four-pole automata are connected to a three-phase network as introductory machines, where the phases are used as separate network lines with individual load elements. At the same time, it is necessary to try to distribute the magnitude of the load currents evenly over the phases, in order to avoid phase imbalance. To remove excess currents, a neutral wire is used, a circuit with a grounded neutral.

Connecting circuit breakers in a switchboard requires a lot of knowledge. First, you need to correctly design the wiring, then choose a location, make diagrams, select a case and components. After all these procedures, you need to install the equipment, and connect the shield to the cable.

Incorrect connection of machines can lead to big problems with the wiring, so it is better to contact an experienced electrician in this matter.

In this article we will talk about the process of correctly connecting the machines to the shield, laying cables and the correct layout of all parts. A modern house cannot be imagined without electricity, this issue should be one of the first places.

Electrical shield for the counter and machines - the choice of installation location

Let's start with the simplest part - where to place the switchboard in the apartment? It is most convenient to place it near the front door in the hallway. In this case, you do not have to pull the power cable far from the site. The best height option is at eye level of an adult. And it is convenient to take the meter readings, and turn off the machines if necessary.

For supporters to shove everything under the ceiling, "for greater safety, as they say, they used to hang counters," let's say the following. Old electric meters with plug fuses were simply mounted on the wall without boxes, and therefore they were hung under the ceiling.

The modern electrical panel has a strong case and is locked with a padlock so that children will not fit in there unless you leave the key in a conspicuous place.

When choosing a place for installing a shield in a private house or cottage, you need to consider where and how the cable is wound up or will be wound up from the overhead line or underground supply line. Data on external networks can be taken from the local power supply.

Buy ready-made or assemble an electrical panel with your own hands

As the old song “what progress has come to” is sung, that you can buy a ready-made shield with a full filling or assemble a ready-made one. If your electrician suggests such a “proprietary” assembly design, then do not be alarmed. Shields are assembled by enterprises and electrical installation firms, including on order or for standard apartment wiring projects.

The main point that needs to be clarified is whether your master worked with ready-made shields before or is this the first experience. If he has installed a dozen or two of these assemblies and knows their features, then feel free to agree. But if you are a "guinea pig" for the first experiment - refuse. Let him collect it himself, with pens, in the old fashioned way.

Scheme of connecting machines in the shield

The layout of the shield in the apartment is one of the main points, but before we deal with it, let's see what elements are included in the design. So that you can understand the designations and composition of the wiring diagram.

Introductory machine.

It is placed to protect the entire wiring circuit. The cores of the main incoming cable are connected to the terminals of the input machine. For convenient work with the electrical panel, a knife switch is often installed in front of the introductory machine.

It allows you to de-energize the entire assembly for the replacement of elements, safe prevention and completely turns off the power supply to an apartment or house. In this case, the power cable is brought to the breaker.

Electric meter.

It is installed after the introductory machine and counts the electricity consumption in the house or apartment. Sometimes the meter stands separately, up to the shield, along with the automatic shutdown. For example, on the site of an apartment building.

Residual current device - designed to protect against electric shock and prevent fires.

The RCD in the circuit can be as one installed after the meter, for example, in a one-room apartment with a small load. Or they put several RCDs on separate lines with high consumption (on an electric stove, washing machine, air conditioner).

Linear machines.

Needed for separate lines for different rooms, household appliances and lighting. They break the circuit if they detect an overcurrent or short circuit, protect the wiring and connected equipment from damage. The operation of the machine can prevent a fire due to heating and ignition of the wire.

Diffavtomat protection.

It can be installed instead of a pair of automatic + RCD on separate power lines for electrical appliances.

DIN rail - a mounting element for installing equipment.

It is attached to the rear wall of the electrical panel housing. Depending on the dimensions of the cabinet, the number of din-rails and the possible number of installed modules may be different. In order not to be mistaken with the purchase of the shield housing according to the number of modules, it is necessary to draw up a wiring diagram.

Connecting tires.

Needed to disconnect the electrical panel and connect the working zeros and ground wires. The shield uses both zero bus-terminals and grounding ones.

Distribution tires.

They are installed for the "bundle" of linear automata, RCDs, difavtomatov. Busbars-combs have reliable insulation and allow you to quickly and safely connect a number of machines through the input terminal block. They can be used both for the current conductor and for the working zero.

What are circuit breakers

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

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

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

It may seem that it is enough to install just the most powerful machine and there are no problems. However, it is not. A high current that has not been triggered by a protection device can overheat the wiring and, as a result, cause a fire.

What is the machine made of?

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

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

Trip mechanism device

The machines have an element that breaks the electrical circuit at critical current values.

Electromagnetic devices. Differ in the high speed of reaction to short circuit. Under the action of currents of an unacceptable value, a coil with a core is activated, which, in turn, disconnects the circuit.
Thermal. The main element of such a mechanism is a bimetallic plate, which begins to deform under the load of high currents. Bending, it has a physical effect on the element that breaks the chain.

Approximately according to the same scheme, an electric kettle works, which is able to turn itself off when water boils in it. There are also semiconductor open circuit systems. But in household networks they are used extremely rarely.

Time-current characteristics of circuit breakers

Devices differ in the nature of the response to an excessively high current value. There are 3 most popular types of machines - B, C, D.

B (3 to 5 xln);
C (from 5 to 10 xln);
D (from 10 to 20 xln).

What does it mean? It's very simple - to understand the range at which the machine is able to work, you need to multiply the number next to the letter by the xln value.

16*3=48A;
16*5=80A.

the machine marked B16 will turn off in the range 48 ... 80A;
marked C16 will switch off in the range 80…160A;
and marked D16 will switch off in the range of 160…320A.

The most common type of machines is C, it is used in almost every home.
D-marked circuit breakers are mainly used in places with consumers that have high starting currents, such as electric motors.
Type B is the most sensitive, rarely used, mainly for the protection of electronic equipment. And it costs more accordingly.

At a current of 100 A, the B16 machine will turn off almost instantly, while the C16 will turn off not immediately, but after a few seconds from thermal protection (after its bimetallic plate has heated up).

Conventions

Different types of machines are marked in their own way for quick identification and selection of the right one for a particular circuit or its section. As a rule, all manufacturers adhere to one mechanism, which allows unifying products for many industries and regions.

Brand. Usually, the manufacturer's logo is placed at the top of the machine. Almost all of them are stylized in a certain way and have their own corporate color, so it will not be difficult to choose a product of your favorite company.
indicator window. Shows the current status of the contacts. If there is a malfunction in the machine, then it can be used to determine whether there is voltage in the network.
Machine type. As already described above, it means the tripping characteristic at currents that are much higher than the rated current. C is used more often in everyday life and B is slightly less common. The differences between the types of electric machines B and C are not so significant;
Rated current. Shows the value of the current that can withstand a continuous load. Rated voltage. Very often, this indicator has two values, written with a slash. The first is for a single-phase network, the second is for a three-phase network. As a rule, in Russia a voltage of 220 V is used.
Breaking current limit. It means the maximum allowable short-circuit current at which the machine will turn off without failure. Current limiting class. Expressed in one digit or absent altogether
Scheme. On the machine, you can even find a connection diagram for contacts with their designations. It is located almost always in the upper right part. Thus, looking at the front of the machine, you can immediately establish what type of current it is intended for and what it is capable of.

What type of machine to choose

When choosing a protective device, one of the main characteristics is considered to be the rated current. To do this, you need to determine what current strength is required by the totality of all consumer devices in the house.

And since electricity flows through wires, the current required for heating depends on its cross section. The presence of poles also plays an important role.

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

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

The first thing to start with is the correct connection of the machine in principle. As you know, the circuit breaker has two contacts for connecting a movable and a fixed one.

On which of the pins you need to connect power to the top or bottom? To date, there has been a lot of controversy about this. There are a lot of questions and opinions on this subject on any electrical forum.

Let's turn to the regulations for advice. What does the PUE say about this? In 7th edition PUE clause 3.1.6. says:

3.1.6. Circuit breakers and plug-type fuses must be connected to the network so that when the plug of the fuse (circuit breaker) is unscrewed, the screw sleeve of the fuse (circuit breaker) remains without voltage. With one-sided power supply, connecting the supply conductor (cable or wire) to the protection device must be carried out, as a rule, to fixed contacts.

As you can see, the rules say that when connecting the machines in the shield, the supply wire should, as a rule, be connected to fixed contacts. This also applies to all RCDs, difavtomatov and other protection devices. From all this clipping, the expression "as a rule" is not clear. That is, it seems, as it should, but in some cases there may be an exception.

To understand where the moving and fixed contact is located, you need to imagine the internal structure of the circuit breaker. Let's use the example of a single-pole machine to consider where the fixed contact is located.

Before us is an automatic machine of the BA47-29 series from iek. It is clear from the photo that the upper terminal is the fixed contact, and the lower terminal is the movable contact. If we consider the electrical designations on the switch itself, then here it is also clear that the fixed contact is on top.

Circuit breakers from other manufacturers have similar designations on the case. Take, for example, the Schneider Electric Easy9 machine, it also has a fixed contact on top. For Schneider Electric RCDs, everything is similarly fixed contacts on top and movable contacts on the bottom.

Another example is Hager safety devices. On the case of circuit breakers and RCD hager, you can also see the designations, from which it is clear that the fixed contacts are on top.

Let's see if it matters from the technical side, how to connect the machine from above or below.

The circuit breaker protects the line from overloads and short circuits. When overcurrents appear, the thermal and electromagnetic releases located inside the housing react.

From which side the power will be connected from above or below for the tripping of the releases, there is absolutely no difference. That is, we can say with confidence that the operation of the machine is not affected by which contact the power will be supplied to.

In truth, I must say that manufacturers of modern "brand" modular devices, such as ABB, Hager and others, allow power to be connected to the lower terminals. For this, the machines have special clamps designed for comb tires.

Why, then, in the PUE, is it advised to connect to fixed contacts (upper)? This rule is approved for general purposes. Any educated electrician knows that when performing work, it is necessary to remove voltage from the equipment on which he will work.

"Climbing" into the electrical panel, a person intuitively assumes the presence of a phase from above on the machines. By turning off the AB in the shield, he knows that there is no voltage at the lower terminals and everything that comes from them.

Now let's imagine that the connection of the automata in the switchboard was performed by the electrician Uncle Vasya, who connected the phase to the lower AB contacts.

Some time has passed (a week, a month, a year) and you need to replace one of the machines (or add a new one). The electrician Uncle Petya comes, turns off the necessary machines and confidently climbs with his bare hands under voltage.

In the recent Soviet past, all machine guns had a fixed contact at the top (for example, AP-50). Now, according to the design of modular ABs, you cannot tell where is the movable and where is the fixed contact. In the ABs that we considered above, the fixed contact was located on top. And where are the guarantees that the Chinese automatic machines will have a fixed contact located on top.

Therefore, in the rules of the PUE, connecting a supply conductor to fixed contacts implies only connecting to the upper terminals for the purposes of general order and aesthetics. I myself am a supporter of connecting power to the top contacts of the circuit breaker.

For those who do not agree with me, the question of backfilling is why, on electrical circuits, the power to the machines is connected precisely to the fixed contacts.

If we take, for example, a conventional RB type switch, which is installed at every industrial facility, then it will never be connected upside down. The connection of power to switching devices of this kind assumes only the upper contacts. Turned off the breaker, and you know that the lower contacts are without voltage.

Connecting circuit breakers

After the machine is selected, it must be connected. Connecting circuit breakers is not a difficult task and everyone can do it.

Automatic switches are installed in the box for electric machines. To securely fix the machine in the electrical panel, it is mounted on a special din-rail. The wires in the terminals of the machine are fixed with bolted contacts.

When installing in electrical panels and connecting supply or outgoing lines, it is necessary to tighten the bolt contacts carefully, without excessive force.

Tightening the contacts should not be accompanied by deformation of the machine case, as this can lead to a violation of the positions of the current-carrying parts inside the machine case, which can cause excessive overheating of the machine and its failure even under slight loads.

When connecting the machine, it is necessary to follow the generally accepted rule: the input (power) is connected from the top of the machine, and the output (load) is connected from the bottom.

In the future, when it becomes necessary to replace, or connect additional wires to the working machine, you will always know to which contact the load and power are connected.

Before connecting the cable cores to the terminals of the machine, the outer insulation is removed from it somewhere around 10-15 cm, after which the cable becomes more flexible and easily bends inside the electrical panel. This simplifies installation, especially if a lot of machines are installed in the switchboard. Next, the internal insulation is removed from the wires by about 5-10mm.

For the need to connect wires of small cross section or stranded wire to the machine, it is advisable to use special lugs.

Where are they used and how are one-, two-, three- and four-pole machines connected

In single-phase networks with a voltage of 220 V, single-pole or two-pole machines are usually installed to protect electrical appliances.

Only the phase wire - L is connected to single-pole circuit breakers.
Both wires are connected to the two-pole, phase - L and neutral wire - N.
Three-pole machines are used in 3-phase networks. Three phases of the power source L1, L2, L3 are connected to the terminals of such machines.
Four-pole machines are used in places stipulated by the rules of the PUE. As a rule, these are four-wire networks with a solidly grounded neutral, which uses three phases L1-L2-L3 and a zero worker - N (TN-S system).

The main mistakes when connecting machines

connection of the ends of the conductors of a flexible stranded wire without termination;
insulation getting under the contact;
connection of conductors of different sections to one terminal;
soldering the ends lived.

The main mistake when connecting machines is the use of a flexible stranded wire without termination. It's easier and faster, but not right. Such a wire cannot be clamped securely; over time, the contact weakens (“flows”), the resistance increases, the junction heats up.

It is necessary to use lugs on a flexible wire or use a rigid single-core wire for installation.

Everyone knows that before connecting the machine in the shield, you need to remove the insulation from the connected wires. It would seem that there is nothing complicated here, I stripped the core to the desired length, then insert it into the clamping terminal of the machine and tighten it with a screw, thereby ensuring reliable contact.

But there are cases when people are at a loss as to why the machine burns out when everything is connected correctly. Or why the power in the apartment periodically disappears when the wiring and filling in the shield are completely new.

One of the reasons for the above described is the penetration of the wire insulation under the contact clamp of the circuit breaker. Such a danger in the form of poor contact carries the threat of melting the insulation, not only the wire, but also the machine itself, which can lead to a fire.

To exclude this, you need to monitor and check how the wire is tightened in the socket. The correct connection of the machines in the switchboard should exclude such errors.

Never connect circuit breakers with jumper cables of different sections. When the contact is tightened, a core with a large cross section will be well clamped, and the core with a smaller cross section will have poor contact. As a result, the insulation is melted not only on the wire, but also on the machine itself, which will undoubtedly lead to a fire.

The “phase” comes to the first machine with a 4 mm2 wire,
and other machines already have jumpers with a 2.5 mm2 wire.

As a result, poor contact, temperature increase, insulation melting not only on the wires, but also on the machine itself.

For example, let's try to tighten two wires with a cross section of 2.5 mm2 and 1.5 mm2 in the circuit breaker terminal. No matter how hard I tried to ensure reliable contact in this case, nothing worked out for me. A wire with a cross section of 1.5 mm2 dangled freely and sparked.

Separately, I would like to dwell on such a method of terminating the wires in the shield as soldering. This is how human nature works, that people try to save on everything and do not always want to spend money on all kinds of tips, tools and all modern small things for installation.

For example, consider the case when an electrician from the ZhEK, Uncle Petya, wires an electrical panel with a stranded wire (or connects outgoing lines to an apartment). He does not have NShVI tips. But there is always a good old soldering iron at hand.

And the electrician Uncle Petya finds no other way out than to irradiate the stranded wire, stuffs the whole thing into the terminal of the machine and tightens it with a screw from the heart. What is the danger of such a connection of machines in the switchboard?

When assembling switchboards, DO NOT solder and tin the stranded core. The fact is that the tinned compound begins to “float” over time. And in order for such a contact to be reliable, it constantly needs to be checked and tightened. And as practice shows, this is always forgotten.

The soldering begins to overheat, the solder melts, the junction weakens even more and the contact begins to “burn out”. In general, such a connection may result in a FIRE.

How to connect an electric meter and machines

use a single-wire monolithic wire for installation;
when using flexible wire, use ferrules;
use non-breaking jumpers;
use a U-bend to increase the contact area.

Use of ferrules on flexible wire

For wiring shields, electricians often prefer a flexible wire with a multi-wire core of the PV-3 or PuGV type. It is easier and easier to work with it than with a monolithic core. But there is one peculiarity here.

The main mistake that beginners make in this regard is to connect a stranded wire to the machine without termination. If you clamp a bare stranded wire as it is, then when tightening, the veins are squeezed and broken off, and this leads to a loss of cross section and deterioration of contact, and the contact itself weakens over time.

Experienced "specialists" know that it is impossible to tighten a bare stranded wire in a terminal. Therefore, if a stranded wire is used during installation, then NShV or NShVI lugs must be used to terminate it.

In addition, if there is a need to connect two stranded wires to one terminal of the machine, for this you need to use a double tip NShVI-2. With it, it is very convenient to form jumpers for connecting several group machines.

Using a U-bend

To connect the strands of outgoing wires and cables to the machines, we remove the insulation from them by about 1 cm, insert the bare part into contact and tighten it with a screw. According to statistics, 80% of electricians connect in this way.

Contact at the junction is reliable, but it can be further improved without wasting time and money. When connecting cables with a monolithic core to the machines, make a U-shaped bend at the ends.

This shaping of the ends will increase the area of contact of the wire with the surface of the clamp, which means that the contact will be better.

The inner walls of the contact pads AB have special notches. When the screw is tightened, these notches cut into the core, thereby increasing the reliability of the contact.

If it became necessary to connect several machines standing in the same row from the same source (wire), a comb bus would be the best fit for this purpose. But such tires are not always at hand.

How to combine several group automata in this case? Make a homemade jumper from the cable cores. To do this, use pieces of wire of the same cross section, or better not to break it at all along its entire length.

Without removing the insulation from the wire, form a jumper of the desired shape and size (according to the number of branches).
Then we strip the insulation from the wire at the bend to the desired length, and we get an inextricable jumper from a single piece of wire.