What is the difference between a difavtomat and a circuit breaker? What is the difference: a difavtomat and a residual current device and the principle of operation of the devices

As mentioned above, these devices have different functions; they are similar only in the type of fastening and in appearance.

What is the difference between an RCD and an automatic machine?

Circuit breaker

- this is the creation of protection for electrical wiring from damage due to short circuits and long-term overcurrent. Without an automatic machine, the electrical wiring would have to be changed very often, because short-circuit currents would melt the wires, and overload currents would burn all the insulation of the wires.

The machine contains electromagnetic protection against high short-circuit currents. It is an electromagnetic coil with a core.

At the moment of a short circuit, the coil creates an electromagnetic field and magnetizes the core, which causes it to push the trigger latch and the machine turns off. If overload currents arise, the bimetallic plates, heating and bending, move the levers and force the trigger mechanism to operate.

Automatic switch ABB

The shutdown time of the overload protection directly depends on the strength of the overload current. The machine body also contains an arc-extinguishing chamber, which is designed to extinguish the spark and increase the service life of the contacts.

Residual current device and its operation

The difference between RCD and circuit breaker is that it has a leakage current protection function, the machine does not have such protection. The RCD contains a differential transformer, which determines the difference in the current of the phase and neutral wires during current leakage.

These currents, amplified by the secondary winding of the differential transformer, are supplied to a polarized relay associated with the trigger, which turns off the protection. Thus, the RCD device is protected against leakage currents.

Residual current devices

Leakage currents can occur when the insulation of a wire breaks down on the housing of electrical household appliances and a person touches it. In this case, this type of protection saves a person’s life. The operation of the RCD is based on determining the difference between the phase and zero currents, so it has two terminals for connecting the phase and zero, and two more terminals for the phase and zero output for connecting the load.

That is, this device is bipolar for single-phase network, and for a three-phase network - four-pole. Also, an RCD differs from a simple machine in that it has a test button to check its functionality. The machine for a single-phase network has a single-pole module, and for a three-phase network it has a four-pole module.

How to properly connect an RCD and a machine

The RCD does not provide protection against short circuits, as well as against overload, therefore, in order for the protection device not to fail, a machine with a rated current lower than the rated current of the RCD must be placed in front of the RCD by one or two orders of magnitude.

Correct connection diagram for Uzo in an apartment panel. After the introductory circuit breaker VA - 47/50A there is an EKF RCD 2/63A/30mA

An example - and a machine - if there is a 50 A machine, then you need to install a 63 A RCD. Thus, we decided the question of what to install, the machine before the RCD or after. The answer is clear, the machine is placed in front of the RCD in order to protect it, de-energize it in time and preserve the device.

One of the stages of installing a home electrical network is to install protective equipment. It is mounted in the apartment electrical panel. In the event of increased load or failure, the device responds quickly to protect the entire system or a separate circuit.

But before installation, you should find out what is the difference between an RCD and a differential circuit breaker in order to properly organize and secure your home network.

We suggest you understand the functional features of switching devices and find out in what situation what is best to use. In the article, we outlined the main criteria for choosing electrical protective devices, and also described the specifics of their connection and operation.

A home electrical system is a complex branched network consisting of many circuits - lighting, sockets, separate power and low-current circuits. It includes all electrical installations that have to be used daily. The simplest among them are sockets and switches.

During the operation of household electrical appliances, unforeseen situations arise, which result in the failure of individual circuits, devices, as well as accidents.

The causes of trouble are the following:

You can encounter overload if you use new powerful equipment in an apartment with old wiring. The cable cannot withstand the total load, overheats, melts and fails.

An excellent example of the thoughtless use of a Chinese-made extension cord without a fuse, coupled with tees. Simultaneous use of several devices on the same power line can cause melting of contacts and insulation, as well as fire

The danger of leakage currents appears when the insulation of electrical cables and devices becomes unusable, or the equipment is installed incorrectly or grounded.

If the current rises above 1.5 mA, the effects of electricity become noticeable, and more than 2 mA causes convulsions.

A short circuit that occurs due to an unintentional connection between zero and phase also leads to irreparable consequences. The result of the formation of an electric arc is the ignition of a separate section of wiring, and often surrounding objects.

To protect equipment, property, and most importantly, the life and health of residents, emergency shutdown devices are used. Without them, modern technology is considered inferior and dangerous.

Load disconnect switching devices

If the electrical system of an apartment or house is divided into separate circuits, it is recommended to equip each line of the electrical circuit with a separate circuit breaker, and install an RCD at the output.

However, there are many more connection options, so first you need to understand the difference between an RCD and a differential circuit breaker, and then carry out the installation.

Circuit breakers - modified “plugs”

When there was no question of a variety of protective devices, when there was excessive load on the line, “plugs” - the simplest emergency devices - were triggered.

Their functionality was improved and received, which operate in two cases - when a short circuit occurs and when the load increases, close to critical.

The design of the machine is simple: several functional modules are enclosed inside a case made of durable technoplastic. On the outside there is a lever for closing/opening the chain and a mounting groove for “fitting” on the DIN rail (+)

One electrical panel can contain one or several switches, their number depends on the number of circuits serving the apartment or house.

The more separate lines, the easier it is to replace or repair electrical devices. To install one device, you do not need to disconnect the entire network.

Image gallery

A prerequisite for assembling a home electrical network is. Breakers trip quickly when the system is overloaded and due to a short circuit. The only thing they cannot protect against is leakage currents.

RCD – automatic protection devices

When selecting devices, pay attention to devices that occupy one module-space. Such models have already appeared on sale, but their cost is slightly higher than traditional ones.

Difficulty connecting wires

The main difference in connection between the two indicated options is the number of wires. Two separate devices have more terminals in total - 6 pieces, while the difavtomat has only four. The connection diagram is also different.

Comparative diagram of installation and connection of a protective pair and a difautomatic device. The result of operation in an emergency situation and the reliability of the devices are the same, but the order of connecting the wires is different

The diagram clearly shows the wiring connections.

When the situation is like this:

• the phase wire is connected to terminal AB;
• the output of the machine and the L-terminal of the RCD are connected by a jumper;
• the output of the RCD phase is sent to electrical installations;
• the neutral wire is connected only to the RCD - at the input with the N-terminal, at the output - it is sent to electrical installations.

With a difavtomat, the connection is much simpler. Jumpers are not needed, just connect phase and neutral to the corresponding terminals, and send them from the outputs to the load.

What does this give to the installer? Facilitates the connection process, reduces the number of wires, and, accordingly, guarantees more order in the electrical panel.

How is triggering diagnosed?

If we consider devices from the middle price segment, then the tandem “automatic device + RCD” has advantages here. Suppose there was an emergency power outage on one of the circuits.

It is difficult to immediately determine the reason for the protection to operate, since it could be a leakage current, a short circuit, or a total load that the wires could not cope with.

When an RCD or circuit breaker is triggered, you can immediately see where to look for the cause. In the first case, there is an insulation problem, in the second, there is an increased load or a short circuit. The latter can be determined by additional characteristics

If the automatic machine responded to a network failure, then it will take longer to look for the cause. It is necessary to check all versions, and this will take more time and effort.

Which devices are cheaper to buy and repair?

There are situations where the choice is based on cost. For example, there is a budget that cannot be exceeded. In this case, the total cost of all connected protection devices plays a decisive role.

At first glance, a larger number of devices are characterized by more at a high price. In fact, everything is different: a universal automatic machine costs a tidy sum, but a set of other devices turns out to be economical.

If you monitor the price tags of all the designated machines, it turns out that one automatic machine is almost twice as expensive as the “AV + RCD” set

It should be remembered that the number of lines is usually 3 or more, so the difference between purchases increases. If for one circuit the purchase of RCBOs is only 1 thousand rubles more expensive, then for five circuits the difference in amounts grows to 5 thousand rubles.

Thus, both automatic devices and RCD units with circuit breakers have their advantages and disadvantages. If RCBOs win in compactness and ease of connection, then they clearly lose in diagnostics and cost accounting.

Conclusions and useful video on the topic

To better understand security devices and choose the right solution depending on the situation, we suggest watching thematic videos.

Interesting information about the operating principle and installation of RCDs:

Some tips from a professional electrician:

What played a role when choosing a difavtomat:

As you can see, the topic of choosing an RCD or RCBO is not in vain: there are many points that speak in favor of both devices. In order to correctly select the optimal protection option, it is necessary to consider the installation and connection conditions, as well as draw up a preliminary estimate.

Do you have anything to add or have any questions about the topic? You can leave comments on the publication, participate in discussions and share your own experience of using RCDs and differential circuit breakers. The communication block is below.

What is the difference between a differential circuit breaker and an RCD? What do they protect against? Which type to choose in the apartment, in the kitchen? What is the difference between an RCD and a difavtomat? Examples of 4 differential protection markings.

TEST:

1. What type of load is it installed on? protective device?

A) for a washing machine

B) to the common line, to the apartment panel

1. What should be the operating current?

1. What type of RCD is used?

A) automatic differential

B) difrel and circuit breaker

1. What will the differential protection in this design protect against?

A) from electric shock

B) from a fire

Possible answers:

1. For the washing machine (A), we select an RCD with a response threshold of 10 mA (A), with the RCD type differential automatic (A). This threshold value protects against electrical injury (A).
2. Protection with a differential current value of 100 mA should be installed in the apartment panel (B). An RCD with a switch (B) will reduce the likelihood of a fire (B).
3. For a washing machine (A) with a threshold of 30mA (A), a differential relay with a machine (B) will protect against electric shock (A).

SIMPLE differences between a differential machine and a relay. We distinguish protection devices according to 4 characteristics.

As an example, we consider a difrel and an automatic machine from IEK.

“Formula” technical differences between RCD and difavtomat.

1st sign. Inscription on the device body. A differential switch means a difrele, and an automatic differential current switch means a differential circuit breaker (RCBO).

2nd sign. The presence of a letter (B, C, D or E - operating speed of the built-in switch) before the operating current value indicates the RCBO.

3rd sign. The diagram does not show a conventional representation of shutdown due to overload and short circuit.

4th sign. Previously, automatic machines were larger in size. Currently this sign is not typical.

Designation of ouzo and difavtomat on the diagrams.

In order to understand the diagram of complex panels, you need to know how the protection devices are shown on the diagram. As discussed above, the main device of the RCD was a difference current transformer that controls the breaking contacts. It is placed on the symbol, Fig. 5

The RCBO, as we have already discussed, has one more active element - a circuit breaker. According to GOST 2.755-87 ESKD, it is designated by a rectangle on the breaking contact (Fig. 6).

IMPORTANT! The given examples of notations are of a conditional nature, because regulatory documents not regulated.

Let's look at the graphical symbols on part of the real circuit (Fig. 7).

In this scheme, the differential relay is switched on in the floor panel after the circuit breaker and the meter. Following the rules of GOST 2.710-81, each element of a single-line network, in addition to the graphic one, also has a letter designation t. In our case, the differential protection Q0 is of type F202.

What 2 dangers does an RCD protect against?

1st danger.

There are quite a lot of devices in our homes that operate on the network. Everyone knows that electric current is dangerous to humans. Under normal conditions, electricity does not pose a danger because... the housings of electrical appliances are insulated, and electric shock through the air is impossible. But there are two rooms in which current poses an increased danger. In the bathrooms there is a washing machine that has an electric motor and consumes significant power during operation. Also in the bathroom and kitchen, current flows through water. In this case (Fig. 1), a path for electricity through the human body is possible. This current, called leakage current (or differential), does not trip the circuit breaker in the panel, but is sufficient to cause severe electrical injury.

2nd danger

Current that flows uncontrollably from the electrical network leads to heating of conductive parts and can cause a fire.

The amount of electricity sufficient to cause injury and to cause a fire varies in magnitude. An RCD (diffuse protection) will help increase the safety of wiring by eliminating these 2 dangers. The differential protection has a fire-prevention effect when installed on groups of consumers (apartment or floor electrical panel). In other cases, the RCD is included in the power supply circuit of a specific consumer.

Definition. A residual current device is a device used to protect people and electrical devices from differential current.

TOP 3 premises with mandatory installation of differential protection:

1. Rooms with high humidity.
2. With metal floors.
3. Premises with devices having a conductive body.

Marking. Designation on the body of 5 main parameters.

Photo 1 shows a differential relay. On the front side of the device, next to the switch, you can see the parameter markings:

1. Operating current of the differential relay (16 A). The automatic transmission accompanying the differential relay should be no less important.
2. Short circuit current (3000) – the maximum value at which the relay retains its functionality.
3. Type of leak. This relay will operate when an alternating differential current appears.
4. Operating AC voltage and frequency (230 V 50 Hz).
5. Rated operating current (30 mA) – the minimum leakage current at which the consumer will turn off.

IMPORTANT! Also on the case there is information about the operating temperature.

1. – the device can be installed outside heated rooms – down to minus 25 degrees.

3 connection diagrams for differential circuit breakers and RCDs.

Let's consider three characteristic schemes differential protection connections.

1. Connecting a differential relay to a separate consumer.

Let's say we want to increase the electrical safety of an individual, most dangerous consumer by turning it on through an RCD (Fig. 2). The consumer is a washing machine installed in the bathroom.

IMPORTANT! The "TEST" button, when pressed, opens the consumer's power supply circuit. This button is used to check the operation of the device.

In Figure 2, the input lines of the power supply network pass through the GA group automaton and are distributed to consumers through the meter. The washing machine is connected using an RCD and a separate circuit breaker AB installed in the phase wire L. A differential relay acts as a protective device in this circuit. Inside such a device, wires L and N pass inside the transformer T (These wires make up the primary winding I). The secondary winding II is connected to the comparison circuit A. The comparison circuit controls the operation of the polarized relay P, which can open the contacts K.

• Normal mode

Figure 2 shows normal operation - the washing machine is working correctly, there are no short circuits. All electricity passing through bus L returns through bus N. The current in winding II, which is equal to the difference in currents in the primary, is zero. The relay does not operate.

• Differential current and short circuit.

If the load malfunctions, electricity leaks (yellow dotted line) inside the washing machine body. A difference current occurs in transformer T of the protection device. Comparison circuit A through relay P disconnects the load from the network. If there is a short circuit in the machine, the AB circuit breaker turns off its line.

1. Connecting a differential machine to a common circuit.

Inside the input panel (Fig. 3 green dotted line) an RCD is installed - in in this case automatic differential Inside it, the phase conductor additionally passes through short-circuit protection (>I) and overload protection (t), as in a conventional circuit breaker. The power supply will be disconnected for any reason for a fire - excess consumption, short circuit to the load and the presence of differential current.

IMPORTANT! RCDs used as fire protection have a higher rated operating current.

1. We distribute differential protection into groups. Leaks of direct and alternating current.

If you install a separate differential automatic for each load - each chandelier, computer, TV, air conditioner, washing machine, then you will get the most expensive option. Using differential relays that respond to a certain leakage current, it will be possible to group consumers and reduce costs (Fig. 4)

In Figure 4, a washing machine with a powerful AC motor is connected through an RCD with a current of 10 mA. Other loads - sockets, lighting, computer - are powered through a differential relay with an operating threshold of 30 mA. At the input, after the meter, a differential relay is switched on as a fire safety device.

How to avoid improper operation of the RCD?

1. Combining neutral conductors from different protections leads to false tripping.
2. When connecting zero and ground, the RCD will not disconnect the load at all, even if a leak occurs.

Answers to 5 frequently asked questions.

1. There is no separate line in our house protective grounding. Will there be any benefit from installing a protective shutdown?

With such wiring, the differential protection will be able to protect against electric shock when touching simultaneously a faulty load and sewer or other metal pipes. If the insulation inside the device is damaged (short circuit to the housing), it triggers will not happen.

1. What operating time should be provided by differential protection?

All shutdown devices must turn off the consumer when a leak occurs in no more than 0.3 seconds. It is better to choose shutdown devices with high performance.

1. If fast protective devices are the best, why are delayed tripping RCDs produced?

Such devices are installed on powerful electricity consumers. When they start or stop, an uncontrolled leakage of electricity may occur.

1. The use of protective shutdown is mainly advisory. In what cases can you not do without it?

The PUE discusses several cases of mandatory use of differential protection. The most typical is the protection of mobile residential trailers and outdoor electrical consumers.

1. And in what cases is RCD not recommended?

In cases where disconnection can lead to a more dangerous result (installation of an alarm on the power line, medical devices)

One of the important components of life safety is housing safety. This is especially true for home electrical wiring - a highly dangerous object. Since modern apartments are equipped with a decent arsenal of various household electrical appliances, the electricity consumption in the apartment is quite large. Accordingly, the load on the electrical cable also increases.

Why do we need protective shutdown devices?

It is known that any material wears out and becomes unusable over time. The insulating properties of both home wiring and internal wires of electrical appliances are lost over time. The resulting power leakage, exposed wires, and oxidation can ultimately lead to the most unpredictable consequences.

It is also possible that short circuits due to faulty home wiring or appliances or due to negligence.

Due to the many electrical appliances used, including those with high power consumption, the electrical wiring of the home power supply often overheats.

In the absence of protective devices, all these factors can lead to irreparable trouble or damage.

To protect yourself from troubles, you should install electrical protective devices: difavtomat (differential circuit breaker) or RCD (residual current device).

Before choosing which protective device to install, you should understand what they are, how they work, how an RCD differs from a differential circuit breaker, what is preferable to choose, because the difference between an RCD and a differential circuit breaker is significant.

Residual current device (RCD)

This device is designed to equalize the current flowing to an electrical appliance with the current leaving the electrical appliance (along the neutral), and recognizes a leak from the electrical network by the difference between them. When the difference reaches a value incompatible with human life (30 mA), the device turns off the voltage. As a result of the almost instantaneous operation of the device, the differential current flowing through faulty insulation or through the human body does not have time to cause significant harm.

An RCD is not only capable of protecting a person from electric shock, but is also capable of preventing fires in wiring due to overheating and malfunction, loss of integrity as a result of mechanical, temperature effects, and aging of wire insulation.

How it works? Let's say the insulation of a phase wire inside the washing machine is damaged. If a person standing on a wet floor touches the body of the washing machine, the RCD will immediately turn off the voltage supply, determining that the current that went into the apartment did not return through the neutral to the residual current device, that is, the incoming and outgoing currents through the RCD are different.

An RCD will also help in the following situation: for example, when drilling a wall with your bare foot resting on a heating battery, you get into a phase wire of the electrical wiring. The electrical circuit “drill – human body – battery” formed in this case can cause cardiac or respiratory arrest. But if there is an RCD, it will immediately “determine” that part of the current has not returned (that which, having passed through the person, went into the battery). In this case, the voltage will also be turned off instantly. In this case, even if a person receives an electric shock, it will not be as strong as it could be.

In the absence of an RCD, any of these reasons can cause harm to a person that is incompatible with life. However, not in all cases an RCD can help. For example, if the home electrical wiring is old and dilapidated. In this situation, the RCD will be triggered constantly and cut off the power due to constant leaks through faulty wiring, which will cause more trouble than it is worth. Therefore, in such a situation, it is preferable to install an RCD pointwise, that is, install sockets with a built-in RCD.

Differential circuit breaker

The difference between the difavtomat is that this device works simultaneously both as a circuit breaker and as a protective voltage cut-off device.

The difavtomat is designed to protect against electric shock when touching live parts of electrical appliances or when a differential current occurs.

In such situations, the differential circuit breaker, like the RCD, instantly trips and cuts off the voltage in the network.

In addition, the difavtomat performs the functions of protecting electrical wiring from short circuits and overloads. This is due to the fact that the design of the difavtomat is similar to a conventional circuit breaker - it contains two releases:

• Thermal release, turns off the power line in case of network overload.
• An electromagnetic release that is triggered when a short circuit occurs.

How does it all work?

1. Just like an RCD, the difavtomat detects differential current. It works similarly to the cases discussed above (examples with a washing machine and drilling a wall).
2. Triggering of the electromagnetic release. Let's say a child pushes something conductive into a socket, for example, a hairpin, or due to an insulation fault, phase and phase contacts occur. neutral wires on your home network or electrical appliances. In both cases, the short circuit will trigger the electromagnetic release.
3. Triggering of the thermal release. Let's say a 16A automatic circuit breaker is installed. They turned on several electrical appliances with a total power significantly exceeding that allowed by the machine, for example a 2-kilowatt heater, a kettle and an iron. Due to heating of the wires, the thermal protection will work, and the electricity will be immediately turned off.

What is the difference between an RCD and a difavtomat?

For homeowners, it sometimes doesn’t matter what exactly they have installed: an RCD or a difavtomat. However, as we discussed their properties and purpose above, the difference between an RCD and a difavtomat is significant, and the level of safety of life and housing depends on what to choose.

Functional difference between an RCD and a differential circuit breaker

1. The main function of a residual current device is to detect differential current in the network - leakage current. If such a situation occurs, a person may first be harmed by touching the metal casing or parts of damaged equipment. Also, when a differential current appears, the insulation of the electrical wiring may heat up, and this is one of the most common reasons why household fires and fires occur. The presence of an RCD can prevent trouble under these conditions.
2. The differential circuit breaker simultaneously performs the functions of both the circuit breaker and the previously discussed RCD. That is, the functionality of the difavtomat is much broader: protecting the electrical network from short circuits, overloads and the consequences of differential current.

Thus, the range of actions of a differential machine is much wider than the narrowly targeted action of an RCD.

When choosing what to install and where exactly, you should remember that the RCD, unlike the automatic circuit breaker, is not designed to detect overloads and short circuits. Some people mistakenly believe that by installing an RCD, they are protected from everything - this is absolutely not the case.

How to visually distinguish an RCD from a difavtomat

At first glance, both devices are quite similar to each other: the case is similar, there is a switch, a “test” button, and a diagram is shown on the case. But upon careful examination, you can find a difference between an RCD and a difavtomat: the circuits are different, the toggle switches are different, and the alphanumeric markings are also different.

One way to visually distinguish devices is by current marking.

The marking in amperes, for example, 16A, is indicated on the body of the RCD. This indicates the 16A current rating that the device is designed to handle. If at the beginning of the inscription there are the letters B, C or D, and then a number, then this is a differential machine.

Which is better: RCD or difavtomat? Having familiarized yourself with the main characteristics, the choice, of course, will be made in favor of a differential machine. This is optimal if the house has a simple electrical wiring diagram. If you have a big a private house with a complex electrical wiring diagram with many groups of wires designed for heavy loads, then it is better to use an RCD and a circuit breaker in a complex that is separately installed on each of the existing groups.

All electrical devices are different from each other, but the devices can perform similar functions. Today we will discuss automatic devices and RCDs, what is the difference and what is their operating principle. First we consider the question of what each of these devices is.

An RCD, in simple words, is a protected shutdown device installed in apartments and in places with a risk of sudden changes in electrical voltage. The advantages and functions of this device include the ability to recognize the difference and strength of current. In the event that there is an increase in the current passing through the device, the system simply opens the network, which makes it possible to stop the short circuit, resulting in a fire hazard or electric shock. Often this device consists of several elements, each of which is responsible for a specific function.

A differential circuit breaker has a significant difference from an RCD, but their task is similar. So, this device is a combination of an RCD and an ordinary machine into one whole. This equipment is used to prevent electricity leakage, short circuits and network overload.

Differential circuit breaker

This device contains thermal and modular protection, which creates maximum comprehensive safety from all possible dysfunctions.

When answering the question of how an RCD differs from a difavtomat, it is important to highlight that the first device performs a protective task only in the presence of voltage leakage from the wiring. Such equipment will be able to turn off the power immediately at the moment of risk and a short circuit. The design of the device plays the role of a power relay in the electrical circuit.

The difference between an RCD and a differential circuit breaker is noticeable only in appearance; the principle of protection is almost the same.

Having put yourself before choosing which is better for ensuring safety in a residential area, an RCD or a difavtomat, you need to understand the existing difference:

• firstly, the basic configuration of the RCD differs from the basic Differential Circuit Breaker in that it engages the protective function exclusively in the event of overvoltage in the wiring or current leakage.
• Secondly, a differential type device, although it performs a similar task, also serves as short circuit protection.
• A standard residual current device has a single module that only detects current differences.
• The opposite circuit breaker contains thermal and electromagnetic network releases.

Attention! If there is a question of choosing an RCD or a difavtomat, you need to act depending on the type of network created in the room.

If purchased, it is important to consider that a differential system will cost significantly more than a conventional protective device.

Automatic modular switch Keaz

The installation and method of operation of the differential machine largely depends on its own technical characteristics. Any interesting feature of the device can be seen directly on its body.

Main technical characteristics difavtomats are considered the same as residual current devices; the manufacturer indicates them on the front panel. Let's consider each indicator separately.

The rated current is the current in amperes that the device can carry for a long time; its values ​​​​have standards in the same way as for circuit breakers. The range can range from 8 to 52 amperes.

The time-current characteristic can be B, C and less often D. Its value is indicated before the rated current indicator. The presence of a letter that denotes this type of characteristic answers the question of how an RCD differs from a differential circuit breaker. Thus, if any letter is indicated before the designation of the rated current, therefore, it is a difavtomat. If this is a number, then the device is considered a regular RCD.

Simple difavtomat

Rated residual current - standard values ​​10, 20, 30, 100, 300, 500 mA. These can be used to protect people from electric shock or as a stabilizer and fire prevention device.

The rated voltage is the type of voltage at which the system will operate under normal conditions. For a single-phase network this figure is 220 V, and for a three-phase network it is 380 V. Let’s consider the subtleties and additional functionality:

1. the number of poles can be two or four, depending on the type of network;
2. operating temperature range is from -23°C to +45°C;
3. there is a connection diagram for the machine, indicated on its front part;

Technical characteristics of the RCD

To correctly orient and decide on the choice of an RCD or a differential circuit breaker, it’s time to discuss the technical features of residual current devices that have a basic configuration.

Each characteristic of the device is indicated on its body; the trademark or brand of the manufacturer may also be indicated here. Basically, the designation of characteristics on the RCD is similar to the previous device, the only difference is the different values. All main characteristics are given as the ability of the device to be in working condition at a temperature of no more than +30°C.

RCDs of different sizes

Attention! For individual residential buildings, in order to protect the group circuit inside the house, it is advisable to install a residual current device with a current leakage rate of at least 30 A.

It is allowed to use shower cabins for boilers and other devices that are located in wet areas of the installation with a leakage force of at least 10 A. For apartment housing, it is best to use a protection installation with a leakage rate of 30 A. Also for a small area and one electrical network, the installation is used One RCD, in the event of a current leak, will completely de-energize the apartment, so the ideal solution is to install it on a separate group of devices for a specific installation. To protect the premises from fire, you can install fire-fighting equipment in the form of an automatic machine with a rated power of 100 to 300 MA.

What is the difference between an RCD and an automatic machine?

You have already become acquainted with the performance of an RCD a little higher, it’s time to consider what an automatic device is, what are the principles of its operation and how it differs from the first device.

A circuit breaker is a device that controls current in an electrical network. The function of this device is to prevent voltage increases and therefore protect against electrical shock. Thus, the permissible value for the circuit is exceeded, and the fuse breaks this voltage. A similar situation arises if you decide to connect several tees with powerful devices into one outlet. From here a critical value appears, which is eliminated by de-energizing the network.

Time-current shutdown characteristic

The general essence of the operation of a circuit breaker

According to the principle, the operation of such a device consists of the operation of releases, depending on which the machines are divided into two types:

• thermal - a bimetallic plate installed in this type of device changes shape when an electric current flows through it. In the event that this force reaches the threshold on which the operation of the automatic device is based, the plate releases the springs, which causes the contacts in the network to disengage;
• electromagnetic - the operating principle of a machine of this type is similar, the only difference is the presence of a coil with a magnetic center.

Any of the varieties of these machines copes with their tasks very well, in addition, experienced electricians still cannot determine which device is appropriate to install in a certain type of network. In fact, we have looked at how to distinguish an RCD from a automatic machine, we have analyzed the difference between an RCD and an automatic machine, so this is a reason to get closer to the issue the right choice these devices.

Three pole circuit breaker

Rules for a good choice: we buy RCD, automatic and automatic devices

The circuit breaker allows you to protect the electrical communication line from overflows and short circuits. Before purchasing directly, you need to obtain a list of information and understand the following things:

1. the purpose of the device, the activity of its components, know how the circuit breaker is designed;
2. requires the ability to understand all the parameters of the device and be able to set them up;
3. the regulatory document and the methodology for selecting a machine are taken into account;
4. take into account the age and material of the electrical wiring;
5. pay attention to some formulas, because when choosing, you will have to calculate the current and cable cross-section in the network.

You should study all the abilities of the machine and their impact during initial work with electricity. It is important to ensure that the characteristics correspond as closely as possible to the indicators for which the machine is selected, for example, the rated current of a device purchased for apartments should be marked B or C. Indicator D is set in special cases. So, first of all, the maximum current is taken into account, now the current of the machine is considered, this indicator is no less important, it is also advisable to include the polarity of the device and its ability to operate.

An example of a wiring diagram in an apartment

Important note! In addition to the main characteristics and operational capabilities of protective equipment, it is important to take into account such a criterion as cost.

Protected shutdown device: subtleties of choice

First of all, when choosing an RCD, it is important to take into account almost all characteristics, namely:

• tension;
• number of poles;
• rated current;
• type of differential current.

Even with careful selection of these subtleties, erroneous nuances may emerge.

Many inexperienced installers often make even critical mistakes when choosing. In fact, there are no devices that would work perfectly and any RCD will have a leak, although it may be minimal and quite far from the norm, however, it is unreasonable to ignore this property.

Note! Natural leakage from the device can cause unexpected operation of the device, which can be regarded as a faulty network condition.

Based on this observation, it is necessary to ensure that the sum of the leakage indicators does not exceed 1/3 of the rated current. This leads to the conclusion that taking into account natural current leakage from the RCD is mandatory.

Differential automatic or what to look for when choosing

Each of the devices that protect people and premises from the electrical network has a number of characteristics, without taking into account and knowledge of which the choice of device is impossible.

Firstly, this type devices for living space should be selected taking into account its phase indicator. Secondly, attention must be paid to the rated voltage. In a residential building, this figure can range from 220 V to 380 V. Consider the possibility of installed releases and the total leakage of the differential circuit breaker.

Each protective device has an accidental break of the neutral conductor, and this condition, as a rule, negatively affects the state of the network and poses a danger to humans, therefore, when selecting a device, you need to understand whether there is protection against this case.

Any difavtomat has the opportunity to test, therefore, before you include it in final work with your electrical network, pay attention to how the device behaves in test mode.

Finally, you received an extensive answer about what kind of RCD and automatic devices they are, what is the difference between them and the operating principle of each of them. Having also familiarized yourself with the characteristics of the differential device, you will be able to make your own choice, of course, in view of competent considerations.