Why the machine knocks out: we look for reasons when turning it on, in the panel, without load. Why does the machine in the electrical panel knock out? Short circuit the machine does not work

Electrics are good as long as they work properly. Any electrical fault baffles most people on the planet. In this article we will look at how to determine a faulty circuit breaker and how to eliminate it.

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Circuit breaker and short circuit

I'll start from the beginning. Circuit breaker or intended for (cables and electrical wiring) premises from short circuit and overload. A short circuit leads to the instantaneous occurrence of overcurrents in the electrical network (currents that are orders of magnitude higher than operating currents).

Any overcurrent, and in residential circuits this is 1.8-12.6 kA, according to the laws of physics, leads to the release of colossal thermal energy. More than one household contact cannot withstand this energy, and at the point of the short circuit a flash or so-called electric arc occurs. If you do not quickly turn off the power supply to the emergency network, then there is a very high probability of a fire, and even worse, injury to a person due to short-circuit overcurrents.

To protect against short circuits, namely to instantly disconnect the emergency network, automatic circuit breakers (circuit breakers) are used. I note that the shutdown does not occur instantly, but during the time of safe contact. This is less than 0.1 sec.

Circuit breaker and overload

The second purpose of a circuit breaker is overload protection. There is a bimetallic plate (thermal release), the overheating of which disconnects the electrical circuit from the power supply. Overheating of the plate occurs when there is an overload in the network. It is clear that heating and, accordingly, switching off the circuit does not occur instantly, but after some time. Depending on the warm-up of the circuit breaker, this time can be less than a second or several tens of seconds.

Let's move on to apartment electrical faults.

Electrical circuit breaker malfunction

Your circuit breaker trips periodically. The probable reasons for this are as follows:

Short circuit in the circuit;
Network congestion;
Damage to wires periodically leading to either a short circuit or overload.

First you need to diagnose the electrical network for overload and short circuit. If these faults are not detected, and the machine still turns off, then a malfunction of the circuit breaker itself is very likely.

Checking the circuit breaker

Do a basic check of the circuit breaker.

Turn off the power;
Turn off all circuit breakers;
Click the circuit breaker charging lever. It should turn on and off with a characteristic “click” sound.
If a click is not heard, the machine is faulty and requires replacement.
If there is a click, use a measuring device to measure the resistance between the terminals of the circuit breaker. When "on" machine resistance should be close to zero. When "off" The resistance of the machine should be close to infinity.

However, even if the diagnostics of the machine showed that the machine is working, this does not mean that the setting (thermal release) of the circuit breaker is working.

Generally speaking, factory failure of circuit breakers is not that uncommon and is significant. What can we say about the malfunctions of the machines that arise during operation.

For example, the machine worked a couple of times and failed. Or it “survived” too much overcurrent and failed.

A malfunction of the circuit breaker itself cannot be ruled out as the main reason for its periodic shutdown.

Advice, change the circuit breaker for a new one, first do it again.

The matter is simple, and such a replacement can save you from major work to find other electrical faults in the apartment.

Surely most of our readers are familiar with the situation when the electricity goes out at home, but the neighbors are fine with it. First of all, you need to check the circuit breakers installed in the distribution board. Most often, it is their disconnection that causes a blackout. home network. In this article we will talk about why the machine in an apartment or house goes off. The reasons for this phenomenon may be different, and it is important to know them in order to prevent unpleasant consequences associated with failure of electrical appliances or fire of wiring.

Features of the circuit breaker

To understand the reasons for the operation of a circuit breaker, you must first answer the question of what this device is for and what functions it performs. Features of AV operation are as follows:

The main task of the device is to protect electrical wiring and household appliances connected to it from too powerful a current that occurs for various reasons.
The device is mounted on a phase circuit, the rupture of which occurs when the packager is disconnected. If the machine has two or more poles, then when it is triggered, the zero circuit will also open.

The AV can de-energize the network both when turned off manually and when emergency situation, which can lead to damage to circuit components.

The machine knocks out: what are the reasons?

Now let's move directly to the question of why the machine gun knocks out in the dashboard. The machine may be triggered for the following reasons:

Overload in the electrical network.
Failure of one of the devices included in the circuit.
Light fixture failure.
The safety device is faulty.

Any of the listed reasons can lead to the AB knocking out. Let's take a closer look at each of them.

Overload

This is the name of the situation when the amount of current in the circuit exceeds the rated value for which the protective switch is designed. For better understanding, let's give an example.

To work with socket groups, AVs are mainly used, the rated current of which is 16 - 25 A. This indicator corresponds to a total power of 3.5 - 5.5 kW. Let us assume that an electric stove with a power of 3 kW, an electric kettle of 1.3 kW, and a microwave oven of 2 kW are connected to the socket group, for the protection of which a 25 A circuit breaker is installed.

If we add up the power of the listed household appliances, we get a load value of 6.3 kW. Considering that maximum load, withstand by the protective device is equal to 5.5 kW, the simultaneous activation of all three devices will lead to the machine being knocked out.

To avoid this, you should not take the calculation of the total load in the circuit lightly. If connecting a device to an outlet group would result in exceeding the total wattage, it should be connected to a different circuit.

An example of incorrect wiring calculations in the video:

Do not try to solve the problem by installing a machine designed for higher power. If its rating exceeds the cross-section that the electrical wiring can withstand, problems are inevitable. In this case, the cable, under the influence of too much current, will heat up until the insulating layer melts and causes a short circuit, and in the worst case, a fire. The machine will continue to supply current to the circuit until a short circuit occurs. Therefore, if a cable with a cross section of 2.5 mm² is used when laying a line, the AB rating for its protection should not exceed 16 A (for an aluminum conductor) or 25 A (for a copper conductor).

Breakdown of a household appliance

If you plug in a faulty household electrical appliance, the likelihood that the machine will turn off is also quite high. Let's look at an example of how to find the device that caused the problem.

Let’s say the network in the kitchen includes an electric stove, microwave and oven. The machine in this chain was knocked out. To determine the cause of the problem, proceed as follows:

We disconnect all units from the network.
We turn on the machine. If it does not knock out without a load, the wiring and protective device are in good condition.
We connect household equipment one by one. If, for example, when you turn on the stove and microwave oven the chain works, but when the oven is turned on, the machine knocks out - the oven is faulty and needs to be either replaced or repaired

Video diagnostic example:

Some types of household appliances (for example, dishwashers or air conditioners) are connected to the network directly, and not through an electrical outlet. Such devices must be disconnected from the protective device installed inside the switchboard - this is the only way to check them.

Malfunction of lighting devices

Now let’s figure out why the machine knocks out when you turn on any lighting fixture. In any case, the cause is a malfunction of the latter, which may be as follows:

Short circuit in the lamp base. To find the faulty element, you need to unscrew them all and, screwing them in one at a time, turn on the lighting device. When, after screwing in the next light bulb, when the light is turned on, the AB is triggered, this means that the cause of the problem has been found. A light bulb found with a broken base must be replaced with a working one. Of course, if the only light bulb in the device burns out and the machine is knocked out, the cause of the malfunction is obvious, and there is no need to waste time searching for it.

Please note that sometimes light bulbs burn out due to a faulty switch - this may also be accompanied by the activation of a protective device.

Burning of the contact between the power cable and the internal wiring of the device. To eliminate the malfunction, it is enough to clean the contact and then properly insulate it.
Short circuit inside the LED chandelier transformer. If turning on such a device results in the machine being knocked out, there is a high probability that this is precisely the problem. To troubleshoot, a non-working transformer will need to be replaced with a working one.

As you can see, the reason for switching off the AV when a lighting device fails is most often a short circuit. In this case, the wiring does not have time to heat up to a critical level, so the operation is caused not by a thermal, but by an electromagnetic release.

Failure of the circuit breaker

The reason for a sudden loss of power can also be problems in the machine itself, but this happens very rarely, especially when it comes to models from well-known manufacturers. But if there is a suspicion that the protective device is faulty, it should be checked by connecting a new one that is known to be operational. You can also disconnect the circuit from this AB and connect it to the adjacent packet in the distribution panel. If these machines also work, you need to look for the problem elsewhere.

Even a seemingly serviceable machine gun can knock out. Video example:

The reason for the failure of a circuit breaker can also be its long-term operation, during which natural wear and tear of its components occurs and their deterioration occurs. technical parameters. This also applies to releases. As a result, the device can operate even if the conductor is slightly heated. Such an AB must be replaced.

What causes a differential circuit breaker to trip?

Circuit breaker differential type may de-energize the network for the same reasons as a normal one (if the wiring gets very hot or a short circuit has occurred). But since it contains, in addition to releases, an RCD, it also reacts to leakage current, so it is not so easy to find the reason for the tripping of the automatic circuit breaker.

If such a device operates without apparent reason, a more thorough check needs to be done.

Inspect the breaker, if necessary, tighten the contacts. Check the condition of the electrical wiring in the distribution board. If a phase conductor touches a grounded metal case, this may cause the differential circuit breaker to be knocked out, although it will not lead to a short circuit.

Let's assume that no faults are found in the switchboard. Consequently, there is a current leak in the protected electrical circuit. Its reasons may be the following:

Faulty electrical appliance. If it penetrates its body, the RCD of the difavtomat is triggered, the task of which is to prevent people from being electrocuted.
Short circuit between the protective grounding wire and the zero phase, which is sometimes done by inexperienced electricians.

Severe thunderstorm. Powerful electrical discharges often cause the differential protective device to be knocked out. In this case, it is better not to turn on the AV until the thunderstorm subsides.
Worn insulating layer of old electrical wiring. In this case, electric current leaks through microcracks and triggers the machine. Since such damage is difficult to see with the naked eye, and the faulty cable does not heat up, it can be difficult to detect the problem.
A stuck “Test” button on the device or a damaged housing part also causes the device to operate. In this case, the faulty device must be replaced.
Installation of the machine is not according to the diagram.

The differential machine must be checked from time to time by pressing the “Test” button with the load off. A working device should turn off. If it continues to work, this indicates a violation of the protective function and the need to replace the device.

Why the RCD knocks out - clearly in the video:

Wiring fault

The reasons for disconnecting the AV may be:

Worn cable insulation layer.
Poor contact in a switch or electrical outlet.

If the problem is in a switch or socket, then to fix the problem you need to open the element, clean the burnt area and connect the cable correctly. With worn insulation, especially when it comes to hidden wiring, finding the problem is not easy.

In this case, a special device will help - a locator, with which you can detect damage to the cable, even if it is hidden in the wall.

Having determined the location of the problem, you need to open it and eliminate the problem, and then seal the groove again.

Conclusion

In this material, we figured out what reasons, in addition to an excessively heating cable, can cause the circuit breaker to trip. Now you know what to do when a light bulb burns out and at the same time the protective device is turned off, as well as how to troubleshoot if the wiring inside an electrical element burns out or in the event of a failure household appliance.

Circuit breakers are commonly used to protect household electrical circuits. modular design. Compactness, ease of installation and replacement, if necessary, explains their wide distribution.

Externally, such a machine is a body made of heat-resistant plastic. On the front surface there is an on/off handle, on the back there is a latch for mounting on a DIN rail, and on the top and bottom there are screw terminals. In this article we will consider.

How does a circuit breaker work?

In normal operation mode, a current flows through the machine that is less than or equal to the rated value. The supply voltage from the external network is supplied to the upper terminal connected to the fixed contact. From the fixed contact, current flows to the movable contact closed with it, and from it, through a flexible copper conductor, to the solenoid coil. After the solenoid, the current is supplied to the thermal release and after it to the lower terminal, with the load network connected to it.

IN emergency modes The circuit breaker disconnects the protected circuit by triggering a free tripping mechanism driven by a thermal or electromagnetic release. The reason for this operation is an overload or a short circuit.

Thermal release is a bimetallic plate consisting of two layers of alloys with different coefficients thermal expansion. When an electric current passes, the plate heats up and bends towards the layer with a lower coefficient of thermal expansion. When the specified current value is exceeded, the bending of the plate reaches a value sufficient to activate the release mechanism, and the circuit opens, cutting off the protected load.

Electromagnetic release consists of a solenoid with a movable steel core held by a spring. When the specified current value is exceeded, according to the law of electromagnetic induction, an electromagnetic field is induced in the coil, under the influence of which the core is drawn into the solenoid coil, overcoming the resistance of the spring, and triggers the release mechanism. In normal operation, a magnetic field is also induced in the coil, but its strength is not enough to overcome the resistance of the spring and retract the core.

How does the machine work in overload mode?

An overload mode occurs when the current in the circuit connected to the circuit breaker exceeds the rated value for which the circuit breaker is designed. In this case, the increased current passing through the thermal release causes an increase in the temperature of the bimetallic plate and, accordingly, an increase in its bending until the release mechanism is activated. The machine turns off and opens the circuit.

The thermal protection does not operate instantly, since it will take some time for the bimetallic strip to warm up. This time can vary depending on the magnitude of the excess current from a few seconds to an hour.

This delay allows you to avoid power outages during random and short-term increases in current in the circuit (for example, when turning on electric motors that have high starting currents).

The minimum current value at which the thermal release must operate is set using an adjusting screw at the manufacturer. Typically this value is 1.13-1.45 times higher than the denomination indicated on the machine's labeling.

The magnitude of the current at which the thermal protection will operate is also affected by the ambient temperature. In a hot room, the bimetallic strip will warm up and bend until it triggers at a lower current. And in rooms with low temperatures the current at which the thermal release will operate may be higher than permissible.

The reason for network overload is the connection to it of consumers whose total power exceeds the calculated power of the protected network. Simultaneous activation various types powerful household appliances (air conditioner, electric stove, washing and dishwasher, iron, electric kettle, etc.) - may well lead to the operation of the thermal release.

In this case, decide which consumers can be disabled. And don’t rush to turn on the machine again. You still won't be able to cock it into the operating position until it cools down and the bimetallic release plate returns to its original state. Now you know during overloads

How does a machine work in short circuit mode?

In case of a short circuit it is different. During a short circuit, the current in the circuit increases sharply and many times to values that can melt the wiring, or rather the insulation of the electrical wiring. In order to prevent such a development of events, it is necessary to immediately break the chain. This is exactly how an electromagnetic release works.

The electromagnetic release is a solenoid coil containing a steel core held in a fixed position by a spring.

A multiple increase in the current in the solenoid winding, which occurs during a short circuit in the circuit, leads to a proportional increase in the magnetic flux, under the influence of which the core is drawn into the solenoid coil, overcoming the resistance of the spring, and presses the release bar of the release mechanism. The power contacts of the machine open, interrupting the power supply to the emergency section of the circuit.

Thus, the operation of the electromagnetic release protects the electrical wiring, the closed electrical appliance and the machine itself from fire and destruction. Its response time is about 0.02 seconds, and the electrical wiring does not have time to heat up to dangerous temperatures.

At the moment the power contacts of the machine open, when a large current passes through them, an electric arc appears between them, the temperature of which can reach 3000 degrees.

To protect the contacts and other parts of the machine from the destructive effects of this arc, an arc-extinguishing chamber is provided in the design of the machine. The arc chamber is a grid of a set of metal plates that are insulated from each other.

The arc occurs at the point where the contact opens, and then one end of it moves along with the movable contact, and the second slides first along the fixed contact, and then along the conductor connected to it, leading to the rear wall of the arc-extinguishing chamber.

There it divides (splits) on the plates of the arc-extinguishing chamber, weakens and goes out. At the bottom of the machine there are special openings for the removal of gases formed during arc combustion.

If the machine turns off when the electromagnetic release is triggered, you will not be able to use electricity until you find and eliminate the cause of the short circuit. Most likely the cause is a malfunction of one of the consumers.

Disconnect all consumers and try to turn on the machine. If you succeed and the machine does not kick out, it means that one of the consumers is indeed to blame and you just have to find out which one. If the machine breaks down again even with the consumers disconnected, then everything is much more complicated, and we are dealing with a breakdown of the wiring insulation. We'll have to look for where this happened.

This is how it is in various emergency situations.

If tripping your circuit breaker has become a constant problem for you, do not try to solve it by installing a circuit breaker with a higher rated current.

The machines are installed taking into account the cross-section of your wiring, and, therefore, more current in your network is simply not allowed. A solution to the problem can only be found after a complete inspection of your home’s electrical system by professionals.

Replacing old fuse plugs with modern ones is one of the main requirements of the PUE. This is due to the fact that conventional plugs cannot cope with the increased loads and simply burn out. When replacing an electric meter or wiring, plugs are replaced “by default.” Also, residents often make this decision on their own and install an automatic machine, the power of which can be calculated based on the planned load.

But quite often people are faced with the problem that the security device is constantly knocked out, often for no apparent reason. The recommendation of absolutely all specialists is that if the machine turns off, start looking for a breakdown immediately, since this can later lead to more serious and sometimes even sad consequences.

In this article we will look at the main factors why this happens, as well as how to find and fix the problem.

Reasons why a circuit breaker trips

There may be several such factors; we will look at each of them in detail.

Permissible load exceeded

Each machine has its own characteristics, which are reflected on its body. One of these indicators is the rated current that the device can carry. If this current is exceeded, after a while the machine is knocked out: this is an automatic thermal release that has tripped to protect the electrical wiring.

There are two ways to solve this problem:

The easiest way (and the most recommended by electricians) is to alternately connect electrical appliances to the network to avoid overloads. For example, if you have a 16A machine installed, it can “withstand” a load of 3.5 kW;
You can replace the circuit breaker with a more powerful one, for example, install the device at 25A. The machine no longer knocks out, since it is designed for a load of 5.5 kW. But this method of solving the problem is applied only if old wiring was changed to a more powerful cross-section (minimum 2.5 square meters for copper conductors).

Pay attention! If an overload shutdown occurs, it will be possible to restart the machine only after some time, when the thermal release has cooled down.

A short circuit has occurred

Another common reason why a machine breaks down is a short circuit. A short circuit can occur due to several factors and in different places. Let's look at this issue in detail.

Short circuits in electrical appliances are very easy to detect. Usually, if there is a short circuit in any electrical appliance, it stops working. Also an indicator is a blackened case or melted wires. In this case, it is enough to disconnect the device from the network and turn on the machine, it will not knock out.

If obvious signs There is no short circuit, all electrical appliances should be turned off. After turning on the voltage, turn on the consumers one by one. When a closed device is plugged into the network, the machine will trip again or it will be discovered that the consumer is faulty.

If everything is fine, try turning on the lights in each room. It happens that the socket or light bulb shorts out, so it knocks out the protection.

Short circuit in electrical wiring

If the above steps did not detect a short circuit, it may be in the wiring. Finding the location of a short circuit in the wiring, especially if it is hidden, will be much more difficult. For this you need. But first, you can check the distribution boxes and sockets. It is in these places that short circuits most often occur.

When checking distribution boxes and sockets, you should first of all pay attention to melted wiring, exposed ends or loose contacts. Such shortcomings must be eliminated: the ends must be reliably insulated, and all contacts must be tightened.

The circuit breaker has failed

You shouldn’t rule out the situation when the machine itself is out of order, this also happens. The reason for this may be a manufacturing defect in the design or mechanical damage to the housing. There are times when you just need to tighten the contacts on the device itself, which have become loose over time. If this does not help, replace the machine with a similar rated current. This is quite easy to do and won't take much time. If the shutdowns stop, it means that the cause was found and eliminated.

These are, perhaps, all the factors that lead to the circuit breaker tripping. There are not very many of them, but any one can cause a shutdown. Let us remind you that if the protection has been triggered, in order to avoid more serious consequences, you should not postpone the inspection of the electrical network until later.

Differential automatic

Quite often in electrical panel apartment or private house installed difavtomat. The reasons why he knocks out are a little more complicated. The fact is that this device combines two protective devices: an RCD and a circuit breaker. Consequently, the reasons that lead to its operation are more extensive and relate to various factors.

We discussed above what causes the circuit breaker to turn off. The same reasons influence the automatic device and cause it to operate. But, in addition, the differential device also works as an RCD, therefore, it responds to leakage current, which is somewhat more difficult to find.

Reasons for triggering

Let us analyze the main reasons for the operation of this protective device and possible places where leakage current is generated.

First of all, if the automatic circuit breaker has tripped, you need to inspect it and, if necessary, tighten the contacts. Also, when examining the protective device, pay attention to the wiring in the electrical panel. Perhaps the phase wire lies on a metal housing that is grounded. This will not cause a short circuit, but may cause the machine to kick out.

If everything is normal in the electrical panel, it means that there is a current leak in the circuit that the device protects. This can happen in several places:

The cause can be any electrical appliance. If it penetrates the body, the difavtomat is guaranteed to turn off: this is one of its main functions, to protect a person from electric shock.
Perhaps the consequence was old electrical wiring, or rather, its worn-out insulation: current leakage gradually appears through microcracks, to which the difavtomat reacts. If the wiring is new, a leak may occur in a poor connection or if the wall is damp, for example due to flooding.
A common mistake made by inexperienced electricians is shorting the neutral wire with protective grounding. This is strictly prohibited, since it leads to the operation of protective devices such as RCDs or differential devices.
Damage to the case or sticking of the test button can also cause the device to trigger. In this case, it is necessary to replace the faulty device.
Weather conditions, namely a strong thunderstorm, often lead to the automatic machine being knocked out. This occurs due to strong atmospheric discharges, which enhance natural current leakage. In this case, you should wait until the storm subsides and then turn on the voltage.
Unprofessional installation or installation of wiring on a quick fix, leads to the fact that the electrical connection diagram of the differential device is not followed. This leads to the fact that it periodically knocks out for no apparent reason.

The serviceability of the device must be checked periodically. To do this, when the load is removed, press the “test” button. A working difavtomat should turn off. If the device does not turn off, it does not perform protective functions, and it is better to replace it with a working device.

Methods for detecting a leak

To find the location of the leakage current, after the automatic circuit breaker has tripped, you need to unplug all electrical appliances from the outlets. After this, the protective device is turned on. If the shutdown does not occur again, it means that some device is breaking through to the housing. You can detect it by calling it with a multimeter.

If the differential device continues to knock out, then the problem is in the wiring. Audit electrical circuit It's best to start with outlet groups and distribution boxes. Special attention you need to pay attention to the places of connections and twisting of wires, the integrity of the insulation and the reliability of the contacts.

After checking all contact groups in the electrical network, proceed to the next stage. It is necessary to check each individual line for current leakage. It is recommended to start from the electrical panel, gradually moving deeper into the house or apartment. Having determined the line or junction box after which the differential current occurs, all twists are disconnected and each wire is tapped.

Thus, there is a circuit where the insulation is damaged. If necessary, change the wiring or isolate the damaged area. Sometimes you have to remove the wire from the wall to do this if the wiring is hidden. But such cases are quite rare: if the electrical wiring is very old, it is better to replace it during repairs or when installing a differential device.

Automatic circuit breakers (CBs) are mandatory devices for any home electrical network to ensure the safety of its operation. Almost everywhere they have replaced the previously so common fuses - the so-called plugs. It’s understandable: automata (as AB is usually called in colloquial speech) - much more convenient to use, more compact, and in terms of reliability of protection they are still much higher.

But sometimes it happens that the circuit breaker, with some stubborn constancy, and, in the opinion of the owner of the apartment or house, for no apparent reason, refuses to work in the on position. That is, he is said to be regularly knocked out. Often this leads the owner to the idea of the need to replace the switch, and also with an increase in the operating current rating. Stop! This is a fundamentally wrong and even extremely dangerous decision! First, you need to figure out the reason, find out why the machine knocks out. It just doesn't happen that way. Yes, there is a small probability that the AV itself is faulty, but most often this is a signal of serious problems in the electrical wiring or in the devices connected to it. That is, the machine, in fact, fully performs its task. And by turning it off, it seems to remind the owner - “Deal with the reason!”

The main functions of a circuit breaker, its basic structure and operating principle

This publication is certainly not intended for professional electricians. Its goal is to show the most ordinary person the possible reasons for the operation of a circuit breaker and “equip” him with the necessary knowledge to identify and eliminate shortcomings. Therefore, it would be useful to first briefly familiarize yourself with the design of the machine - this will make it easier to understand how it works and why it can be knocked out.

So, the vast majority of modern circuit breakers intended for installation in household networks are compact, modular devices for mounting on a DIN rail. The entire device is assembled in a plastic case with a characteristic rectangular shape. On the front side of the machine there is a switch lever, there is a marking with the main performance characteristics device. On the back side there is a special groove and a latch for mounting on a rail.

At the top and bottom there are screw terminals for connecting wires when installed in a home wiring diagram. The number of pairs of contacts may vary - from one to four. Accordingly, the switches themselves, according to this criterion, are divided into one-, two-, three- or four-pole. In a household single-phase 220 volt network, two-pole ones are more often used - at the common input, and single-pole ones - on separate lines. Devices with three or four pairs of contacts are usually designed to operate on a three-phase 380 V network.

The dimensions of the machine are strictly standardized, and depending on the number of poles, it can occupy from one to four module spaces on the DIN rail of the distribution board (cabinet).

What is the purpose of a circuit breaker?

One of its functions is quite obvious - it can work as a regular switch. That is, if necessary, depending on the installation location in general scheme, the owner has the opportunity to turn off either the entire home (apartment) electrical network or a separate section of it. This is often required for preventive, repair, and electrical installation work. The function is certainly important, but still does not determine the essence of the operation of this device.
The second task, and already a safety plan, is to protect the home network (or a certain section of it) from reboot. Alas, many consumers of electricity do not think at all about the fact that any conductor has a certain limit on the current it carries. And the picture when several quite powerful ones are switched on at once through a whole “cascade” of extension cords and tees to one outlet electrical appliances, can be seen quite often.

Too much current in the wiring causes it to heat up, which leads to the appearance and fire of insulation, plastic housings of sockets or connected devices. And this is one of the common causes of fires.

A correctly sized circuit breaker is designed to prevent this situation. If the maximum load current in the line is exceeded, after some time it will de-energize.

The third task is to instantly open the circuit in the event of a short circuit in the network. Deterioration, insufficiency or previous melting of insulation, violation of electrical installation rules in distribution boards and boxes or on sockets, problems with connected electrical appliances - all this can lead to the fact that the phase wire closes to zero without load.

The danger of a short circuit is difficult to exaggerate. The current in a closed circuit reaches values of several thousand amperes, which, naturally, no wiring can withstand. That is, if the circuit is not immediately interrupted, large-scale melting and fires of wiring and devices are possible. And this is an almost guaranteed fire with very disastrous consequences.

This means that the task of the automaton is to the shortest possible time, measured in milliseconds, respond to a short circuit by breaking the circuit in order to prevent a large-scale accident.

The design of the circuit breaker is precisely designed to perform all these three tasks. Let's take a look at its design and how it works in emergency situations.

So, at the top and bottom of the circuit breaker there are screw terminals (item 1) for connecting the incoming and outgoing wires towards the load. In the illustration, just for the sake of compactness, the device is shown horizontally. In fact, the side on the right in the picture will be facing up. And most often it is to this terminal that the supply wire is connected.

The input terminal is connected to a fixed power contact (item 2). A movable power contact (item 3) works in tandem with it. It is the closing and opening of this pair that provides either switching or breaking the circuit. That is, the illustration shows that in this case the machine is in the off position - the contacts are open.

Internal switching in the switch, in addition to current-carrying metal parts, is carried out using powerful flexible conductors (item 4).

On the front side of the machine there is a switch lever (position 5). Most often, its lower position corresponds to turning off the device, and its upper position corresponds to turning on the device.

The lever is mechanically connected to a special mechanism, which is a combination of levers, springs and stoppers (item 6). When the lever is moved to the upper position, this mechanism ensures the closure of the movable power contact with the stationary one. And this contact is in a spring-loaded state, that is, when the stopper is acted upon under the action of the spring, the contacts will automatically open.

But this stopper, which keeps the contacts closed, can be influenced in three different ways. Firstly, simply by moving the lever to the lower position, that is, when manually turning off the machine. And secondly, the shutdown can be triggered by any of the two releases located inside - thermal or electromagnetic.

The electromagnetic release (position 7) ensures that the machine operates in the event of a short circuit. It is a coil whose turns are part of the total flow of current through the switch. The device is made according to the solenoid principle, that is, a spring-loaded metal core is placed inside the coil, which is mechanically connected to a movable power contact.

When a current normal for the electrical network flows through the coil, the generated electromagnetic flux is insufficient to overcome the spring force and retract the core. But if a short circuit occurs in the network, the strength of the passing current instantly increases hundreds of times. Accordingly, this is accompanied by an instant increase in the magnetic flux created by the coil. The solenoid core is sharply retracted, which leads to the breaking of the lever mechanism from the stopper and, under the action of a spring, the moving contact being thrown away from the stationary one. It takes longer to write and read, but in reality, in a split second the chain breaks.

True, they usually try not to reach hundreds and thousands of amperes - the operation of an electromagnetic instantaneous release is usually calculated for a certain excess of the passing current relative to the specified rating. Based on these indicators, circuit breakers are divided into classes according to the so-called time-current characteristic, designated in Latin letters. IN household network The following classes can be used:

B – operation when the rated current is exceeded by 3÷5 times;
C – 5÷10 times;
D – 10÷12 times.

The response time, depending on the size of the current excess, is determined by special graphs.

Typically, class B is used to protect specific leased lines. Several lines can be combined and protected in a panel by a class C machine. Class D is more suitable for powerful equipment with electric motors. In domestic conditions they are rarely used.

This distribution of machines by class and recommended installation location, by the way, also provides the necessary selectivity. That is, for example, in the event of a malfunction on a particular line, only its automatic circuit breaker can operate, and the more “senior” one will remain in the on position, ensuring the normal operation of the remaining sections. It is clear that this greatly simplifies troubleshooting in the event of frequent protection activation.

The thermal release (pos. 8) is designed to ensure operation automatic shutdown when the permissible load current is exceeded. It is a bimetallic plate, which is part of the general circuit of the current passing through the machine. If the current is within the specified rating, the plate is motionless. But when an excessively large load is connected to the circuit, resistive heating of this plate begins due to an increase in current. Due to its bimetallic structure, it begins to bend when heated. And at a certain moment, the latch holding the lever mechanism in the on position will move out of place. And again, under the action of the spring, the fixed and movable power contacts will open.

True, here the operation does not occur instantly, but with a certain delay. That is, if the current excess is observed for a certain time. When assembling circuit breakers, they undergo calibration - for this there is a special adjusting screw (item 9). But after assembly, this screw becomes inaccessible, and you can knock it down factory setting the user will not be able to.

Such a delay is necessary, if only because, when starting up many devices, very significant current surges are observed, which then returns to the nominal value. This is especially true for appliances and household appliances equipped with electric drives - power tools, refrigerators, pumps and more. And so that the machine does not react by turning off every short-term start, this possibility is provided.

Contact break at large values current is usually accompanied by the occurrence of an electric arc. To prevent it from causing damage to the machine, it is equipped with a special arc extinguishing device (item 10). This is a separate chamber with a row of parallel metal plates installed in it. The arc breaks against them, loses its strength and becomes unable, for example, to melt the body or other internal parts switch. The gases formed during arc combustion are discharged through a specially provided window (item 11).

Finally, on the back side of the machine there is a shaped groove for installation on a DIN rail, and a movable latch that provides reliable fastening on it (pos. 12).

We hope the reader has clarity about the circuit breaker design. We can move on to consider the reasons for its frequent operation.

Why might a circuit breaker trip?

First of all, you should not perceive the operation of the machine as some kind of “tragedy”. If only because it was reassigned for this purpose. And in most cases, by turning off this device, it saves the home electrical network and the devices connected to it from large-scale accidents, which can result in very serious consequences.

The next thing is that troubleshooting will be much easier if your home network is properly organized. We are talking about the so-called selectivity of installation of automatic machines. That is, all internal wiring should ideally be divided into separate lines, each of which is protected by its own AV with a correctly selected rating.

The commercially available lines of circuit breakers may have a rated current of 6, 10, 16, 20, 25, 32, 40, 50 or more amperes. It's important to choose correct model for each group. So, for example, at the entrance to an apartment or small private house a paired two-pole circuit breaker of 25, 32 or 40 amperes can be installed (depending on the cross-section of the wires at the input). Next, separate lines are organized for the most powerful home equipment (stove, oven, washing machine or dishwasher, etc.), protected by their own circuit breakers with a rating of 16 amperes (this results in a load power of 3.5 kW). Similar lines are laid to socket groups located in the rooms and in the kitchen. And separate lines combine lighting fixtures - here a machine with a rating of 10 amperes is sufficient.

What does this achieve? If a specific line is knocked out, and the rest continue to operate normally, then the troubleshooting area is sharply narrowed. Or, for example, the input circuit breaker was knocked out, but the rest of the circuit breakers with a lower operating current rating remained turned on - with a high degree of probability we can assume that the reason for the operation lies directly in the distribution panel.

One more important note. It is not enough to install a circuit breaker with a rating adequate to the connected load. The cross-section of the wires on this line must also correspond to the same load. Otherwise, if, for example, a 16-amp machine is installed, but it is connected to a line where an aluminum wire with a cross-section of 1.5 mm is laid, the protection may not cope with the task. At least until the overload causes the wiring insulation to melt, followed by a short circuit.

Core cross-section copper wire, mm² (in brackets - aluminum)	Maximum current under continuous load, A	Maximum load power. kW	Rated current of the circuit breaker, A	Maximum circuit breaker protection current, A	Scope of application in home (apartment) conditions
1,5 (2,5)	19	4.1	10	16	lighting, alarm devices
2,5 (4,0)	27	5.9	16	25	socket blocks, floor heating systems
4,0 (6,0)	38	8.3	25	32	powerful climate control equipment, water heaters, washing machines and dishwashers
6,0 (10,0)	46	10.1	32	40	electric stoves and electric ovens
10,0 (16,0)	70	15.4	50	63	power input lines

Well, now – directly to the reasons for the protection’s operation.

Line overload

This is perhaps the most common reason tripping of the circuit breaker. And this situation only means that the device conscientiously coped with its task.

And the origins of the cause lie in the improper organization of the home electrical network or in the ill-considered operation of household appliances. It happens that too many outlets are connected to one socket group at the same time. large number devices. The total load, and therefore the current in the line, exceeds the rated one, and the thermal release in the circuit breaker is triggered, thereby protecting the line from emergency overheating.

At the moment the machine is turned off, you should immediately see which line is overloaded (if this is organized), and what specific load was connected to it at that time. As a rule, the picture turns out to be clear. And when one of the devices is turned off, the knocking out of the machine stops. True, when turning it on again, you have to give a pause of several minutes - the bimetallic plate of the thermal release must cool down, otherwise the machine simply will not turn on.

So, how is a problem like this solved?

The first, of course, will be measures of the “administrative plan,” so to speak. That is, you should understand yourself and explain to everyone at home how and when you can connect powerful household appliances at the same time. Try to separate the devices you cannot do without into different outlet groups. Or even just keep in mind that, for example, if something is being cooked in an electric oven, you should not turn on the washing machine or a powerful water heater at the same time. In a word, prioritize the use of certain devices, the simultaneous operation of which leads to overload.
The second way to solve the problem could be to purchase a circuit breaker with a rating one step higher (for example, instead of 16 - 25 amperes). But this is only possible if the cross-section of the laid wires allows, as mentioned above. If the section is insufficient, then the problem will only worsen and lead to even greater trouble.
This suggests a third solution option - this major renovation with replacement with high-quality cables with a sufficient cross-section of copper conductors. This approach becomes especially relevant in houses or apartments where old aluminum wiring still remains, which is not at all designed for the modern level of electricity consumption.

If the wiring does not allow the installation of a machine of a higher rating, and the owners’ immediate plans do not yet include a major reconstruction of the home electrical network, all that remains is the rational distribution and use of the load. And, interestingly, in our time this can be solved, so to speak, at the “hardware level”. We are talking about special devices called load priority relays.

Such a device becomes especially relevant if the power limit allocated to an apartment or house is insufficient to simultaneously turn on all installed equipment. That is, there is frequent knocking out of the general machine at the input.

It works something like this. Household appliances are pre-distributed according to priority purpose. That is, the first group, say, includes those whose shutdown is undesirable under any conditions. Further, depending on the number of possible lines on the relay, other groups are “staffed”, and the priority of each subsequent one is less than that of the previous one.

If the permissible load exceeds the set rating, the group with the lowest priority will be turned off. If this is not enough, a shutdown will occur and next line. But the most important devices will remain in operation, and there is no need to worry about overheating of the wiring. When the load normalizes, the relay will automatically turn on the lines in the reverse order.

The operation of the load priority relay, of course, requires a separate detailed consideration. And a publication on this topic will definitely appear on the pages of our portal.

Failure of household appliances

Another situation is when the connected load is clearly adequate to the rating of the machine. There is nothing to say that the line may be overloaded. But the defense works with “unshakable stubbornness.”

The reason may be a malfunction of the connected (plug-in) household appliance. In his electrical diagram Problems could occur that could lead to a short circuit.

It is not difficult to identify such a deficiency. First of all, you should, again, detect what exactly was connected to the power supply at the time the protection was triggered. After this, all these devices are turned off. Next, the machine starts up - and if the operation does not occur, then we can say that the accident area has already been localized in a certain way.

The next step is to sequentially connect previously switched off devices to the power supply. And, naturally, the “behavior” of the machine is monitored. The device whose connection to the outlet will trigger the protection clearly has internal faults and needs to be repaired. And you will have to stop using it until the problems are fixed.

So you should check all disconnected devices - the picture should be completely clear. But when checking, do not forget about increased security measures. Since there are reasonable assumptions about a malfunction of a device, a phase breakdown on its body cannot be ruled out. That is, special care should be taken to avoid electrical injury.

Home Wiring Defects

In the event that all the load on the line is turned off, but the machine knocks everything out early, the reason may lie in a wiring fault. Here everything is somewhat more complicated - you will have to tinker a lot to find the defective area where the short circuit occurs.

They usually start with sockets and switches. When the line is turned off, the covers are removed from them, and then the condition of the terminals is first checked. It often happens (and more often if the wiring is aluminum) that the contact is weakened, sparking occurs on it, the insulation burns, from where it is only one step to a short circuit. And tightening the contacts can solve the problem.

This can also be caused by weakening of the spring metal contacts of the socket due to their wear. The issue is resolved by installing new socket. In this case, it is necessary to get rid of the burnt ends of the wires with melted insulation.

What to do with a socket that has become unusable?

It is always necessary to monitor the condition of the sockets - it is easier to identify a problem at the initial stage and prevent its development than to “shove it up” later. possible consequences. How to diagnose problems and read them in a special publication on our portal.

You should immediately check the lighting fixtures - short circuits also occur in their internal wiring. The defect may also lie in the cartridge - burnt contacts or even a short circuit at its terminals.

If the inspection of sockets, switches and lamps does not yield anything, we move on to working with distribution boxes. All wire connections should be checked very carefully - broken contacts in twists or loose terminals lead to sparking, overheating of conductors, melting of insulation and, as a result, a short circuit. It happens that the electrical tape previously used to insulate the twists unwinds, for example, due to a previous flood from the upper neighbors. And there should definitely be no exposed sections of wires in the junction box.

If everything is in order here, you will have to look for the damaged section of the hidden wiring. First, you need to try to remember whether, shortly before the accident was discovered, the wall was drilled (driving nails into it). It happens that such actions without preliminary “reconnaissance” violate the integrity of the wiring or its insulation, which leads to short circuits.

Troubleshooting hidden wiring is best done using a special device. If it is not there, then you have to disassemble the connections in the wiring boxes and ring each section of the network individually, identifying the place or, or short circuit of the conductors. And if there is no experience in such operations, then it is better to immediately call a specialist.

Well, if a damaged area is identified, nothing but replacing it will help the matter.

Video: Possible reasons for frequent tripping of a circuit breaker

Other possible triggering cases

In addition to those mentioned, there may be other reasons for the protection to trigger. They are not that common, but it doesn't hurt to know about them.

It happens that a machine with a low operating current rating (6 or 10 A) turns off when the incandescent light bulb burns out. At the moment when the hair breaks, an electric arc can form, and this will be perceived by the switch as a short circuit.

There is no defect in this, and no special measures are required. It’s just that the time has come to abandon incandescent lamps and switch to more modern and economical light sources.

Even before all the above operations, it always makes sense to immediately check whether everything is in order with the circuit breaker itself. Specifically, whether the wires in its terminals are tightened well.

If the terminal is not tightened sufficiently, sparking cannot be ruled out, which leads to heating first of the metal contact, and from it - of the bimetallic plate of the thermal release. Hence the protection triggers. But it’s better than the case ending up with such high heating that the body of the device itself begins to darken and then melt.

By the way, this is a fairly common defect when using aluminum wiring. This metal itself is very ductile and with constant pressure from the screw (plate) of the terminal it begins to “sag”. That is, contact deteriorates over time on its own. This requires regular tightening, which is naturally forgotten. So if your house or apartment still uses aluminum wiring, one of your priorities should be to reconstruct your home electrical system by replacing aluminum with copper.

Which cable should be used for home wiring?

According to current regulations, wiring in residential buildings should only be carried out copper wires. Where aluminum remains, sooner or later a major replacement will still have to be carried out. A special publication on our portal will help you figure out the choice.

Finally, if a thorough check of the home network and connected devices still does not reveal any defects, we can talk about a malfunction of the circuit breaker itself. It is clear that we are talking about a hidden malfunction - if the body of the machine is melted or, say, the lever is broken, then it must be replaced a priori.

And the reason for a hidden defect in a machine gun often lies in the desire of the owner, as they used to say at the Sukharevsky market in Moscow, to “buy for pennies.” That is, purchase a high-quality device for minimal money. Alas, this doesn’t usually happen in life.

A circuit breaker is, without exaggeration, a device for ensuring security - for your personal safety, for your family members, for your home, for all your acquired property. Is there any point in saving in such matters? Is it possible in sane should I purchase such a device cheaply second-hand or in a Chinese online store, where no one can guarantee the quality of the product and the correctness of its operation?

And even in a normal store, attention should first of all be paid to machines from well-known manufacturers who have proven the high quality of their products. Alas, not everything is going well with some brands.

From domestic producers You can highlight the brand “Contactor”, which, by the way, belongs to “Legrand”, which already speaks for itself. KEAZ machines are also a good solution in terms of price and quality ratio. You can meet a lot positive feedback about young products Russian company"DECraft" But regarding IEK machines, despite their affordability and wide range of models, there are, alas, more complaints from users. than enough.

We will conclude the publication by posting a video showing a comparison of circuit breakers.