The procedure for connecting machines. How to properly connect a circuit breaker: useful tips for a home handyman

Connecting circuit breakers

Connections of machines in a single-phase network

The installation option for circuit breakers depends on the selected single or three-phase network.

For a single-phase network, one or two-pole circuit breakers are used; for a three-phase network, three or four-pole circuit breakers are used. Multi-pole circuit breakers are assembled from several single-pole circuit breakers.

The protection mechanism is connected into one system through special connections. For example, when the network of one pole of the machine is disconnected due to overload or short circuit. the entire multi-pole circuit breaker will turn off. A phase is connected to a single-pole circuit breaker; in the event of an accident, the circuit breaker turns off the phase.

This option for connecting the machine is suitable for a TN-C system network, where the neutral wire is connected separately, through the neutral bus. If the house uses the TN-S system, then the input is made by three wires, phase, zero - blue wire and yellow-green PEN protective grounding wire.

Connecting single-pole circuit breakers in a TN-S network system with neutral and protective grounding

In this situation, the installation of circuit breakers is carried out on two-pole circuit breakers, where the phase and neutral are connected to the upper terminals of the input circuit breaker, and the protective yellow-green wire PEN is connected to the grounding bus in the electrical panel.

Use of two-pole circuit breakers in a TN-S network system with neutral and protective grounding

Connecting machines in a three-phase network

In a three-phase network, three or four-pole circuit breakers are used. In the TN-C system, all three phases L1, L2, L3 are connected to the upper terminals of a three-pole circuit breaker, and the neutral wire is connected to the neutral bus of the electrical panel.

Connecting a three-pole circuit breaker in a TN-S network system with neutral and protective grounding

In the TN-S system with protective grounding PEN, three phases are connected to the upper terminals of a four-pole circuit breaker, and the blue neutral wire is to the upper terminal of the fourth pole of the input circuit breaker marked N. The yellow-green protective PEN wire is connected to the grounding bus of the electrical panel.

Connecting wires to the machine

The installation of the circuit breaker is carried out on a DIN rail, the length of which is selected at the rate of 17.5 millimeters per single-pole circuit breaker. When installing a cable, 10–15 cm of outer insulation is removed from it to improve the flexibility of the wires and ease of installation.

The ends of the wires are protected by 7-10 mm and placed under the terminal contacts. There is no need to tightly tighten the screw connections of the machine to avoid distortion of its mechanisms. When installing wires into the terminals of the machine, make sure that the insulation of the wires does not get under the contacts. In the best case, there will be an unreliable connection, and in the worst case, the phase on the contact will be lost.

Mounting connection rail for automatic machines

For a multi-core cable, to ensure reliable contact, it is better to install copper lugs of the appropriate size. In an electrical panel where several circuit breakers are installed in a row, it is convenient to install a copper connecting bar for circuit breakers (comb). It is cut to the required length and installed in the required sequence instead of wire jumpers.

How to connect it correctly and are all such circuit breakers the same?

What are the features and nuances when installing two-pole circuit breakers and what does the “bible” of electricians, PUE, say about this?

First things first.

So, where are two-pole circuit breakers used?

Based on the name of the machine, it follows that they are used where the power supply to electrical equipment is supplied through two wires and simultaneous automatic switching of the two poles of the machine is required.

For example, a 220/36 Volt step-down transformer, where a two-pole circuit breaker is installed on the secondary winding to protect against overload.

If to protect the primary winding of such a trans you can use a single-pole circuit breaker: connect a phase to it, and connect the zero through the zero bus in the switchboard, then you cannot protect the secondary winding this way.

There is no phase and no zero, but there is a linear voltage between the two terminals of the secondary winding with a voltage of 36 Volts. Well, to put it simply, there are two different phases.

And in this case, a two-pole machine is used.

I want to clarify right away - there are two types of two-terminal networks - 2P and 1P+N. What is their difference?

The 1P+N circuit breaker, or as it is also called, “single-phase with zero,” differs in that the functions of automatic protective shutdown are available only in the “phase” pole.

The second pole simply serves as a load switch and is used to connect the neutral wire; it is also used in automation as a normally open contact, or you can simply connect a wire through it to a signal lamp and you can control the on position of the machine; the lamp will light up.

Of course, such a machine can be used as a simple single-pole one. In this case, we must connect the “phase” to its place (in no case to terminal N!).

For residential electrical wiring, such 1P+N circuit breakers are quite suitable and have advantages over single-pole ones.

For example, if an RCD installed in front of such machines is triggered, to find the fault it will be enough to turn off all the machines, then turn on the RCD and turn on the machines one by one until the faulty electrical wiring line is found.

And if there were simple single-pole ones, then we would have to open the shield, unscrew the wires from the neutral bus, etc...

The second type of two-pole circuit breakers is 2P.

They already have both poles protected from overloads and short circuits, and when connecting, it makes absolutely no difference where to connect the zero and where the “phase” is connected. These machines are wider than 1P+N.

It is not necessary to connect a 2P phase and a neutral to the machine; it is quite possible to connect two phases, both the same and opposite. In addition, the jumper between the power keys can in this case be removed and the load controlled separately.

You cannot remove the jumper if the phase with zero is connected through the machine!!!

This is a gross violation of the PUE and is very life-threatening! If the zero key is disconnected from a short circuit, a life-threatening potential (voltage) may appear on the body of the electrical device!

Such machines also don’t care which side the load is connected to - top or bottom, it doesn’t matter. This is also not prohibited by the rules, but I still recommend connecting the power from above and the load from below.

And if you do the opposite, then only in the most extreme cases.

I myself had such cases when I inserted old electrical wiring into an installed panel and its length was not enough to connect to the upper terminals of the machine.

And in order not to split hairs - extend the wire, install the junction box, I connected it to the lower terminals. But such cases were very rare and an exception to the rule.

And now about the main thing.

Such two-pole circuit breakers can be installed as input circuit breakers, as well as for group and individual loads. The PUE does not prohibit this.

PUE is the “bible” of an electrician, it stands for “Rules for the Construction of Electrical Installations”.

This is what the “bible” tells us:

paragraph 6.6.28. “ In three- or two-wire single-phase Lines of networks with a grounded neutral can use single-pole switches, which must be installed in the phase wire circuit, or bipolar, while the possibility must be excluded disconnecting one neutral working conductor without disconnecting the phase conductor. ”

In our apartments, we mainly use two-wire (two cores in a wire - 220 volts) single-phase electrical wiring with a grounded neutral.

Important note: if the electrical wiring is three-wire, that is, phase, neutral and ground, then the ground wire is prohibited in all cases open!

Grounding (PE wire) is never connected through a circuit breaker, plugs, fuse, etc.! Disconnection is only allowed through the plug connector!

I think I’ve basically told you everything, if you have any questions, ask, I’ll answer!

(may also be called a machine, switch) - a switching device designed to supply electricity. current to the object and its shutdown automatically if problems occur in the electrical network. Products Design and principle of operation

To properly connect the machine to work, you need to understand its design and operating principle.

Sectional view of a circuit breaker with a thermal release

The main parts of the product are as follows:

frame;
switching device;
control mechanism (handle, button);
arc extinguishing chamber;
screw terminals (top, bottom).

The housing and control mechanism are made of durable plastic that does not support combustion. A switching device consists of both moving and fixed contacts. The pole of the machine is a pair of these contacts, which has its own arc-extinguishing chamber. Its main purpose is to extinguish electricity. an arc that appears when contacts under load break. It is a set of steel plates with a special profile shape. They are equidistant from each other and isolated from each other. The electric arc generated during the malfunction is attracted to these plates. Here it cools and goes out. The number of pairs of contacts can be from 1 to 4.

For example, a two-pole one has 2 moving and 2 fixed contacts. The machine has a position indicator: red means that the product is on, and green means it’s off. This allows you to quickly navigate and find out what condition the machine is in.

From the outside of the machine, only the handle, screw clamps located at the top and bottom, and the indicator are visible. Everything else is located inside the device body.

The housing has special jaws called a retainer that allows the circuit breaker to be quickly mounted on a special rail called a DIN. If the product is replaced, the same clamp allows you to quickly dismantle it: by loosening the fastening screws on the terminals of the machine, just move the clamp down. The machine will be removed from the rack without any effort. Today, such slats are an integral part of any electrical panel. Many modern electronics and automation elements are manufactured specifically for installation on a DIN rail.

The mechanism that opens the switch when an emergency occurs is called a release. Each type of release has its own device.

The thermal release in its design has a special plate called bimetallic. It is made by pressing from 2 dissimilar metals, which have different coefficients of linear expansion. The plate is connected to the electrical circuit in series with the load. During operation of the device, the plate is heated by the current passing through it, and it bends towards the metal, which has a lower expansion coefficient. When the current increases above the rated value (overload), its bending will lead to the machine switching off. For this purpose, the design provides a trigger mechanism.

The operation of the switch is also influenced by the ambient temperature. Therefore, some products adjust the response time according to this temperature. In any case, the higher the current value is from the rated value, the faster the thermal release operates. Some of them work in a matter of seconds.

Sectional view of a circuit breaker with a magnetic release

A coil with a winding and a core is a magnetic release. The winding is made of insulated copper wire. Included in email. the circuit is in series with the contacts - the load current moves through it. If it exceeds the set permissible value, then the magnetic field of the coil will move the core, and it, in turn, will act on the shutdown device. This will cause the circuit breaker contacts to open.

Machine design with a combined type of control

Some types of switches provide a time delay in the event of a short circuit and are called selective. This product has a special panel where the switch off time is set. This makes it possible to turn off the specific area where the short circuit occurred and where other circuit breakers were triggered. As a result, there is no need to completely disconnect the facility from the power supply; it is possible to disconnect only the area where the emergency situation has occurred. As a rule, these are powerful devices that have a semiconductor type release.

The design of the machine may not have a release, and then it is called a switch-disconnector.

Before you begin installation, you need to select the right product. How many to supply: one or several, at what power, from which manufacturer? Do you need an introductory machine? Should I connect before or after the meter? These are the most frequently asked questions.

Each switch is characterized by the following parameters:

rated current (indicated in A);
operating voltage networks (indicated in B);
number of poles;
maximum short-circuit current;
(the response time of the device depending on the magnitude of the flowing current is the ultimate switching capacity (UCC)).

The last parameter is indicated in numbers, which indicate at what current value the device will remain operational. In everyday life, products with numbers of 4500, 6000 and 10000 A are used.

Manufacturers usually indicate all this directly on the body of the device, including the circuit diagram for putting it into operation and the symbol of the switch.

Placing the technical characteristics of the machine on the device body

The switch is selected based on the load power and the cross-section of the connected wire. They are usually selected according to 2 parameters: overload current, short-circuit shutdown current.

Overload occurs when devices and instruments are connected to the network, the total power of which will lead to excessive heating of conductors and contact connections. Therefore, the machine that will be installed in a specific circuit must have a shutdown current greater than or equal to the calculated one. It is determined by summing the power of the electrical devices intended for use (indicated in the passport). Next, the resulting figure is divided by 220 (remember physics and Ohm’s law) and the desired overload current is obtained. One more circumstance must be taken into account: this current should not be greater than the current that can flow through the conductor.

Short-circuit tripping current – this is the value at which the circuit breaker turns off. It is also calculated and then selected according to the type of protection. It contains the values of the shutdown current in relation to the probable short-circuit current. This current depends on the type of load in the electrical network. In everyday life and for small objects, devices with the symbol B, C are used, and at the input - D (see the placement of the symbol in the figure).

Most often, in addition to the circuit breakers for each group line, the electrical circuit also includes an input circuit breaker, an RCD or a differential circuit breaker.

Connection diagram of protection devices in the distribution panel

The diagram indicates the following main points that are important to know:

complete set of distribution board (input machine, electric meter, RCD, circuit breakers from running lines);
paired operation of the input circuit breaker and the RCD (this is evidenced by the lower rated current of the RCD than that of the input circuit breaker);
installation location of the RCD (should be close to the power supply input, so it is mounted immediately behind the meter);
installation of one RCD protecting the entire electrical circuit (leakage current should not exceed 30 mA);
when the neutral protective conductor (PE – black lines) and the neutral working conductor (N – blue lines) are separated;
conductor cross-section and wire grade;
how the phase conductor is connected to the main devices of the circuit (red lines in the diagram).

External view of the distribution panel with installed devices for metering electricity consumption. energy and electrical protection circuits is shown in the figure below:

Placement of protection elements and meter in the distribution panel

Manufacturers

Circuit breakers are manufactured in many countries. The main requirement for this device is that it must be made of high-quality materials and have a long service life. The price of an automatic machine of the same power can vary quite widely and depends on the manufacturer.

The highest quality machines are produced by the following companies:

French: Legrand, Schneider Electric, Hager;
Slovak SEZ Krompachy;
German: ABB, Moeller, Kopp;
American General Electric;
Russian: Kontaktor, KEAZ.

Installation

Before installing the switch, it is necessary to clearly determine where to correctly connect the wires or power cables: at the top or bottom of the product, or, more simply, to the moving or fixed contacts. And although many do not comply with this condition and connect without taking this factor into account, it is still more correct to turn to the PUE, which for electricians is the document whose instructions must be followed. It clearly states: the supply wire (cable) must be connected to fixed contacts. They are located on top in all modern machines.

Installation cannot be performed without tools and control devices. You must have:

screwdriver set;
assembly knife;
tester or screwdriver with indicator.

Single pole

Installation is carried out in single-phase networks, in which the input is made of 2 wires (usually these are old buildings): phase (L) and zero (PEN), i.e. made according to the TN-C system. The power cable is connected to terminal 1 of the machine, from terminal 2 it is distributed through the counter to machines of specific groups. The supply zero is supplied through the meter to the PEN zero bus. This is clearly shown in the figure below.

Connection diagram for single-pole circuit breakers in the distribution panel

Bipolar

Installation is carried out in single-phase networks, in which the input is made by 3 wires, one of which is phase (L), the second is zero (N), the third is ground (PE), i.e. connection is carried out using the TN-C-S or TN-S systems. Here the supply wire is connected to terminal 1, zero to terminal 3 and securely fastened. Terminal 2 is the output, the phase passes through the electric meter. The input device, which is an RCD, distributes power evenly across switches combined into separate groups. From terminal 4, which is the output, the zero passes through the electric meter, the RCD and is connected to the N bus. The wiring is shown schematically in Figure 10.

Connection diagram in the panel of two-pole circuit breakers

The passport for the machine specifies the requirements for connecting conductors to its terminals. The information must be carefully studied. This applies to both the cross-section and type of connection of the conductors, as well as the length of the stripped part.

Typically, for machines used in everyday life, the wires are stripped of insulation to a length of up to 1 cm using a mounting knife. It is also necessary to pay attention to the color marking of the wires. White or brown color for the supply wire (phase), blue (light blue, black) for the neutral conductor, yellow-green or green for the ground wire.

After stripping with a mounting knife, the bare part of the wire is inserted into the contact clamp from above or below, depending on which conductor is connected (phase, ground or neutral). Next, they are securely fixed into the appropriate terminals using screws. You'll need a screwdriver here. The reliability of the conductor's fastening is checked by twitching. When connecting a flexible wire to a circuit breaker, you must use special lugs, which makes the connection more reliable.

When connecting conductors to the machine, it is necessary to monitor the following factors:

no insulation should get under the contact clamp;
Do not tighten with great force; this may deform the housing and, as a result, lead to failure of the device, malfunction or shortened service life.

In many cases, several circuit breakers are installed in the distribution panel. Inexperienced electricians connect them together with jumpers. This is acceptable, but it is better to use a special tire. It's called a comb. It is usually cut to the required size, and then the phases are connected to the circuit breakers in the sequence provided for by the fundamental electrical circuit. scheme.

External view of the connecting bus

Electrification

To correctly carry out electrification of an object of any complexity, you need to perform the following steps:

draw up an electrical diagram taking into account all the features of the electrical wiring of a particular object;
correctly determine the total power consumption;
determine the number of electrical groups and the power of each group;
decide on the installation location of the distribution panel and how many modules it should have;
select a metering device (electricity meter);
correctly connect outgoing and incoming lines;
connect the switchboard to the networks of the energy supply company.

Connection. Video

You can learn about the electrical circuit from the video below.

All this can only be done by competent electricians who are well versed in the power supply of simple and complex objects. They know the modern electrical engineering base and are able to equip an electrical panel with everything necessary at minimal cost. In addition, based on many years of experience, they can provide useful advice on saving energy and improving the power supply to existing facilities.

A circuit breaker is not a symmetrical electrical device, like an incandescent lamp or heating element. The connection method determines which parts of the protective device will be de-energized and which will remain energized when triggered.

Circuit breaker device

Structurally, the machine consists of electromagnetic and thermal releases combined in one housing. The thermal release protects the circuit from overloads, and the electromagnetic release from short circuit overcurrents. When triggered, the release activates the moving contact and opens the circuit. The spark-extinguishing chamber, inside of which the contacts are located, prevents the formation of an arc.

Protective devices for single-phase 220 V network

The housing design does not differ from automatic machines or RCDs, which makes it possible to install a differential automatic machine in standard boxes using a DIN rail.

Connecting a differential circuit breaker 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 body of the differential machine there are markings for the zero and phase inputs, 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 machines are very reliable and unpretentious, but deviation from these rules does not guarantee correct operation of the device.

For a single-phase network, the use of two-pole circuit breakers is preferable to single-pole ones. The reason is simple - when voltage appears on the neutral wire, one movement of the flag completely breaks the circuit, preserving both the line and the electrical appliances connected to it. The case design of the two-pole switch allows installation on a standard DIN rail.

It should be taken into account that the width of such a machine is usually twice as wide as a single-pole machine. The upper contact pair is intended for connecting phase and neutral wires.

There are no strict rules for the location of phase and neutral wires, but if you connect a number of two-pole circuit breakers, you must 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 is zero.

The stripped wires are fixed in the contacts using screw clamps. There should be no exposed wire sections. Do not forget that there is a very short 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 a circuit breaker, it is important that the body of the circuit breaker is securely fastened and does not break from its mounting location when turned on or off.

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 upper terminal of the machine is responsible for the voltage input, and the lower terminal is responsible for the output. The wires laid and mounted on the wall are brought to the machine and stripped.

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

The phase incoming and outgoing wires are clamped in the terminals of the machine, while the neutral wire can pass in transit through the box or, if necessary, secured to the zero rail.

The 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.

Installing and correctly connecting the machine in the distribution cabinet is not a problem. Even an ordinary person can cope with this, who only encounters electricity when they insert a plug from a household appliance into an outlet or turn on the lighting. But the question of how to properly connect the machine is still often asked by ordinary people. The thing is that even among electricians there are disputes about connection methods. That is, connect the power wire to the circuit breaker from above or below.

Let's not argue here, but simply turn to the rules for the construction of electrical installations (PUE), where in one of the paragraphs, or more precisely, in paragraph 3.1.6, everything is clearly described. Neither the photo below is an extract from this paragraph of the PUE.

So, the rules recommend connecting the power wire to a fixed contact in the machine. And it is located right at the top. But let's be completely honest and read the rule again. There are no strict restrictions in it, that is, it is only advisory in nature. Therefore, when answering the question of how to connect a circuit breaker from below or from above, you can use two options. Moreover, the device will disconnect the network from overloads and short circuits in any case, regardless of the connection diagram.

And yet, why is this clause present in the PUE? To answer this question, it is necessary to consider the design of the circuit breaker.

To move on to the connection diagrams of the machine, you must first understand its design. And since we are interested in connecting wires to the lower or upper contacts of the device, we must understand that both contacts (moving and fixed) are made of different metal alloys.

When it comes to the AC network, when switching the machine, its contacts burn out evenly, and there is no difference where the wires are connected. If the machine is located in a circuit with direct current, then the choice of connection contact is an important component of the correct and long-term operation of the device itself. At high current levels, metals are transferred from one contact to another, so in such networks the supply wires must be connected only from above, that is, through a fixed contact.

Now let's move directly to the machine itself. To help you understand what is inside this device, we recommend that you familiarize yourself with the picture below.

The two main elements that perform the protective functions of the machine are electromagnetic and thermal releases.

Electromagnetic release

This element is a protective element, which is triggered if a short circuit occurs in the electrical circuit where the machine itself was installed. It is at this moment that huge currents appear in the circuit (almost thousands of times higher than the rated current value). To prevent wiring and household appliances plugged into the sockets from burning out, the release instantly turns off the supply network. The shutdown time is milliseconds. By the way, there is a certain marking on time-current characteristics. It is designated by letters of the Latin alphabet and applied to the body of the circuit breaker itself. In everyday life, types “A”, “B”, and “C” are more often used.

The design of the electromagnetic release itself is a core (solenoid) around which the coils of the spring are located. The solenoid is connected directly to the moving contact of the machine. But the spring is connected in series with the power contacts and the thermal release. The rated current is too small for the magnetic flux created inside the coil to retract the core and thereby open the contacts. As soon as a short circuit occurs in the network, that is, a current of enormous magnitude appears, large magnetic fluxes arise inside the coil (spring), the spring compresses and draws in the core, which in turn immediately opens the power contacts. This means that the network will be de-energized.

This element is intended to protect the electrical circuit if large loads other than the rated ones begin to operate in it. This is a delayed release, so to speak. It will hold the overload for a certain time, and if the latter does not drop to the nominal value, it will turn off the power. Let us immediately make a reservation that the thermal release will not respond to short-term current surges.

Purely structurally, the thermal release is a bimetallic plate, which, in fact, is a console. Its free end is connected to a mechanism that will disconnect the contacts. At rated current, the free end of the plate is located close to the lever of the release mechanism. As soon as an overload begins in the circuit, the plate begins to heat up and bend, thereby acting on the lever, which in turn acts on the mechanism, and the latter on the contacts, opening them.

This is a rather complex circuit breaker device and operating principle.

Connection diagrams

So, the operating principle of the circuit breaker is now clear, you can proceed directly to its connection diagrams. Let's start with the fact that machines can be connected to single-phase and three-phase networks. What machines are needed for this? If the conversation is carried out on single-phase networks with a voltage of 220 volts, then either a single-pole device or a two-pole device is usually installed in them. The circuit itself will depend on whether it uses a ground loop or not.

If two wires enter the house (zero and phase), then a single-pole version can be installed in the distribution cabinet. In this case, the phase circuit will pass through the machine itself. If three wires enter the house (phase, neutral and ground), then the common circuit breaker must be two-pole. That is, a phase is connected to the first terminal of the device, and zero to the second. Grounding through a separate terminal box is routed to consumers (lights and sockets). Next, the wires from the circuit breaker are routed to the meter, then to single-pole circuit breakers installed in groups, but as described in the first case. By the way, below is the system for connecting the machine.

Use of two-pole circuit breakers in a TN-S network system with neutral and protective grounding

Connecting machines in a three-phase network

Connecting a three-pole circuit breaker in a TN-S network system with neutral and protective grounding

Connecting wires to the machine

The installation of the circuit breaker is carried out on a DIN rail, the length of which is selected at the rate of 17.5 millimeters per single-pole circuit breaker. When installing a cable, 10 - 15 cm of outer insulation is removed from it to improve the flexibility of the wires and ease of installation.

Mounting connection rail for automatic machines

Content:

Automatic switches, called automatic machines or switches in everyday life, refer to switching devices and are intended to supply electric current to any object. The main function of these devices is to automatically turn off the current supply in the event of an emergency or network malfunction. The machine protects the electrical circuit from short circuits, overloads and voltage drops above the permissible value.

In old houses, in the power supply system the neutral wire was not only working, but also at the same time performed a protective function. In modern buildings there is a clear separation according to the purpose of working and protective conductors. 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 machines themselves can be mounted in a distribution cabinet by mounting them on a DIN rail or on a special mounting panel.

Device and principle of operation

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

Durable plastic that does not support combustion is used to make the housing and control mechanism. 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 contacts under load are broken. The chamber itself is made in the form of a set of steel plates having 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 cools down and fades away. The number of pairs of contacts in different models of machines ranges from 1 to 4. The devices have position indicators. Red indicates on and 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 lock on the body that allows you to quickly install the machine on and just as easily 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 automatic machines the function of a disconnecting device is performed by a coil with a winding and a core. Insulated copper wire is used for winding. The coil is connected to the electrical circuit in series with the contacts, since it is through it that the load current moves. If this current exceeds the established 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 consists of a special bimetallic plate. For its manufacture, two types of metals are used, dissimilar in composition and with different linear expansion coefficients. The plate is connected to the circuit in series with the load. During 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 more the current exceeds the rated value, the faster the thermal release operates.

Installation of circuit breakers

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

At the beginning of installation, the input circuit breaker is connected. If there are several lines in the circuit, isolated from each other, they are separated from the input circuit breaker. Its power must be no 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, resistant to the inclusion of power tools and other powerful equipment.

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

Single pole The switch is used when installing sockets and lighting systems.
Bipolar The machine is suitable for high-power appliances such as an electric stove or boiler. In case of overload, 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 a 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 eliminate the load, the load is connected in a delta pattern. This connection does not require a neutral conductor, and the consumer is connected to its own switch.
Four-pole A circuit breaker is most often used as an input switch. The main condition for connection is the uniform distribution of the load on all phases. When connecting equipment in a star configuration or three separate single-phase wires, excess current will flow through the neutral conductor.

With all loads evenly distributed, the neutral wire begins to perform a protective function in the event of unexpected 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 thoroughly cleaned and tinned.

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

Input wires are connected to two clamps located on top -. The lower clamps hold similar outgoing conductors distributed to sockets, switches and electrical appliances. All wires are properly clamped into terminals using screws. Connections must be checked manually. To do this, the conductors need to be gently moved from side to side. If the connection is poor, the core will wobble in the terminal and may even jump out of it. In this case, the terminal screw needs to be tightened.

Upon completion of installation, voltage is supplied to the network and the operation of the circuit breaker is checked.

How to choose the right machine

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

The response 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 of 4500, 6000 and 10000 amperes are most often used. All technical characteristics are indicated by manufacturers directly on the device body. This also includes the connection diagram, as well as the symbol of the machine.

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

The tripping current during a short circuit also causes the machine to shut down. It is selected by calculations 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 a circuit breaker

When performing electrical installation work, serious mistakes are sometimes made that can lead to negative consequences during 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 panel is designed specifically for the top connection.
A common mistake is to over-tighten the contacts with fixing screws. This can lead not only to damage to the core, but also to deformation of the product body.
Sometimes the conductors are connected incorrectly to each other. It is necessary to pay close attention to the markings and connect the phase and neutral wires located on top with the same wires located below.
In some cases, one two-pole circuit breaker is replaced by two single-pole ones. This absolutely cannot be done, since they do not provide simultaneous separation of phase and zero.
Often, when fixing the core in contact, insulation gets into the seat. This leads to 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 the specific machine model. This operation should be carried out using a stripping tool.

A negative role can be played by the incorrect choice of a circuit breaker, which subsequently is not able to withstand the planned loads. Therefore, it is recommended to first perform all the necessary calculations, especially. It should be remembered that when making calculations, the value of the machine must 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 service life of the wiring.