Uzo or differential. What is the difference between an RCD and a differential circuit breaker? Abbreviation on the body

Tsugunov Anton Valerievich

Reading time: 3 minutes

To ensure safe operation of the electrical wiring of modern apartments, today they are increasingly choosing residual current devices (RCDs) or differential circuit breakers. The use of each of them ensures early shutdown of the section of the electrical circuit in which there are insulation faults. In addition, with the correct organization of automatic protection of the electrical network using such devices, reliable disconnection of consumers is ensured in the event of overloads or short circuits. At the same time, the main difference between an RCD and a difavtomat is the need to install and use an additional device together with such a device. circuit breaker.

It should be noted that for the correct functioning of protection against large differential currents, it is necessary to have a three-wire single-phase system, which includes a grounding wire. Such a wiring system is now widely installed in new buildings, but is extremely rare in old houses.

To answer the question of how an RCD differs from a difavtomat and which device is more preferable to choose for use in your apartment, you need to familiarize yourself with their main technical characteristics, operating principles, as well as design and operation features.

Application of RCD

It is used for switching in a network that supplies groups of consumers during the flow of currents operating under normal operating conditions.

The main task of the RCD is to disconnect the section electrical system, if a differential current occurs in it that exceeds the permissible value.

The occurrence of leakage current is explained by the presence of some insulation resistance of the wiring and electrical consumers. Since this resistance cannot be infinitely large, the so-called normal leakage current will always flow through it, the value of which must be within certain acceptable limits.

In order to better understand what unwanted processes occurring in the electrical network the RCD or RCD protects from, consider the following diagrams.

The first of them depicts a case of electric shock to a person, which occurs as a result of touching the ungrounded body of an electrical device with broken insulation. This circuit has a circuit breaker that disconnects its contacts in the event of an overload current or short circuit, but such protection does not operate when a phase is shorted to ground.

The second figure shows the path of leakage current when the insulation of the grounded body of an electrical appliance is broken. Since the resistance of human skin is much higher than the resistance of the ground loop, in this case electric shock does not occur. However, the metal parts of the housing have a certain potential relative to ground.

The third diagram shows an electrical circuit in which, in addition to the circuit breaker, an RCD is used. If a leakage current occurs, the value of which exceeds the rated value, the automation breaks the circuit.

If you use such protection in electrical networks, whose consumers do not have grounding, then for its operation it is necessary to create a closed circuit between the metal body of the device and the ground. As a rule, such a circuit closes if a person touches the body of the electrical installation.

Thus, the use of an RCD allows you to open the electrical circuit in the following cases:

1. If a person touches an ungrounded electrical installation body that is energized due to insulation damage.
2. If a leakage current occurs through the grounding loop due to a violation of the insulation of live parts, the value of such current must exceed the permissible value.
3. In case of incorrect connection of the neutral and ground wires in the electrical installation.
4. When the neutral wire breaks.

The characteristics of each model are marked on its body in the form of special markings. The main ones are:

1. Rated current and type of time-current characteristic, for example, C63. This means that the rated current is 63 A. The time-current characteristic is the dependence of the tripping time of the switch contacts on the current flowing through them. For circuit breakers used in power supply systems of various objects, these characteristics vary. In apartments and residential buildings, machines with C-type characteristics are used.
2. Leakage current (0.03 A, 0.1 A), at which that part of the circuit breaker that responds to the magnitude of the differential current is triggered.
3. Rated voltage (230 or 400 V).
4. Type of machine (for working with alternating or rectified direct current).
5. Schematic diagram of connection.

To answer the question of how to distinguish an RCD from a difavtomat, just look at them appearance. Although at first glance the differences are not very noticeable, for a knowledgeable person they are, as they say, obvious:

1. The RCD does not indicate the type of time-current characteristic.
2. At the automatic machine in schematic diagram, applied to its body, two additional switches are installed, indicating thermal and electromagnetic releases.
3. Name of the device (VD or RCBO).

A residual current controlled circuit breaker has the following advantages:

• When installing the difavtomat, there is no need to install any additional protective equipment.
• Almost all such devices are equipped with a special indication that allows you to accurately determine what triggered the device: a large leakage current, a short circuit or an overload.

When answering the question posed, how does an RCD differ from a difavtomat, you need to consider the following. Judging by the quantity and quality of the functions performed, there is not much difference in which device to choose: a difavtomat or an RCD. Moreover, the cost of the combined device is even higher than the combined price of an RCD and an ordinary machine. In addition, if one of the separate devices fails, you can repair or replace it without removing the second one; this is much cheaper than repairing a difavtomat.

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, as a result of the occurrence of 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.

Various damage to electrical devices may occur at any time in electrical wiring. To reduce the risk of electrical hazards, household protective devices that perform various functions are used.

A circuit breaker, an automatic circuit breaker and an RCD together increase electrical safety, quickly turn off emergencies, and save people from. However, they have serious differences in operation and design.

To analyze them, we first consider the types of possible faults in the electrical network that these devices eliminate. They may appear:

2.overload of wires. Modern powerful electrical appliances generate large currents, which create increased heating of the current-carrying conductors in poorly executed wiring. During this process, the insulation overheats and ages, losing its dielectric properties;

The situation with the appearance of malfunctions can worsen:

old aluminum electrical wiring, laid decades ago using outdated technologies. It has long been exploited to the limit of its capabilities when powering modern electrical appliances;

poor-quality installation and use of roughened protective devices even in a new electrical circuit.

To simplify the explanation of the differences between protective devices, we will consider only those devices that are designed for a single-phase network, because three-phase designs work in exactly the same way according to the same laws.

Differences in protective devices by purpose

Circuit breaker

The industry produces many varieties of it. They are designed to eliminate the first two types of noted faults. For this purpose, their design includes:

a high-speed electromagnetic trip coil that eliminates short-circuit currents and a system for extinguishing the resulting electric arc;

a time-delayed thermal release based on a bimetallic plate, eliminating overloads that occur within electrical circuits.

A circuit breaker for residential buildings is connected to one phase wire and controls only the currents passing through it. It does not react at all to emerging leakage currents.

Residual current device

An RCD in a two-wire circuit is connected through two wires: phase and zero. It constantly compares the currents circulating in them and calculates their difference.

When the current leaving the neutral conductor matches the value entering the phase conductor, the RCD does not turn off the circuit and allows it to operate. If small deviations of these values ​​occur that do not affect the safety of people, the residual current device also does not block the power supply.

The RCD removes voltage from the wires suitable to it in the event that a dangerous leakage current occurs inside the controlled circuit, which can cause harm to human health or operating electrical equipment. For this purpose, the residual current device is configured to operate when the current difference reaches a certain setting.

In this way, false alarms are eliminated and opportunities are created for reliable operation of the protection to eliminate leakage currents.

However, the design of this device itself does not have any protection against the possible occurrence of short circuit currents and even overloads in the controlled circuit. This explains the fact that the RCD itself must be protected from these factors.

The residual current device is always connected in series with a circuit breaker.

Differential automatic

Its design is more complex than that of a circuit breaker or RCD. During operation, it eliminates all three types of faults (short circuit, overload, leakage) that can occur in electrical wiring. The difavtomat has in its design electromagnetic and thermal releases that protect the RCD built into it.

The differential circuit breaker is made in one module and has the functions of a circuit breaker and a residual current device combined.

Considering all of the above, we can conclude that we need to further compare the characteristics of only two designs:

differential machine;

protection block made of RCD with circuit breaker.

This will be technically justified and correct.

Differences in protection according to operational characteristics

Dimensions

The modern modular design of devices with the ability to mount them on a DIN rail significantly reduces the space required for their installation inside an apartment or floor panel. But even this technique does not always eliminate the lack of space for equipping electrical wiring with new protective devices. RCDs with an automatic circuit breaker are manufactured in self-contained housings and mounted in two separate modules, while the automatic circuit breaker is mounted in just one.

This is always taken into account when creating a project for electrical work in new houses and panels are chosen even with a small reserve of internal space for future modifications to the circuit. But when reconstructing wiring or minor repairs of premises, replacing panels is not always done, and the lack of space in them can become a problem.

Performed tasks

At first glance, an RCD with a circuit breaker and a difavtomat solve the same issues. But let's try to make them more specific.

Let’s say that in the kitchen there is a block of several sockets installed to power various appliances of unequal power: a dishwasher, a refrigerator, an electric kettle, a microwave oven... They turn on randomly and create a load of a random value. In certain situations, the power of several operating devices may exceed the rated value of the protections and create an overcurrent for them.

The installed automatic transmission will have to be replaced with a more powerful one. When using an RCD, it is enough to replace a cheaper circuit breaker.

When it is necessary to protect one electrical device connected by a separate, dedicated line, it is better to use a differential circuit breaker. You just have to choose it according technical specifications specific consumer.

Installation work

There are no big differences in attaching one or two modules to a DIN rail. But when connecting wires, the amount of work becomes greater.

If the automatic circuit breaker and the RCD cut into the phase and neutral wires, then jumpers will also need to be laid to the circuit breaker for connection to the phase wire in series with the RCD. In certain cases, this may complicate circuit assembly.

Quality and reliability

Among some practicing electricians, there is a definite opinion that the durability and performance of protections depend not only on the factory assembly by their manufacturer, but also on the complexity of the design, the number of parts included in the design, adjustment and fine-tuning of their technologies.

The difavtomat is more complex, requires more operations to configure the interaction of parts and in this regard may be somewhat inferior to RCD designs from the same manufacturer.

However, to apply this technique to all manufactured devices, to put it mildly, is not entirely correct, although many electricians abuse this. This is a rather controversial statement and it is not always confirmed in practice.

Maintainability and replacement

Failure can occur at any time protective device. When it cannot be eliminated on site, you will need to purchase a new device.

Buying a automatic rifle is more expensive. In the case of operating an RCD with a circuit breaker, one of the devices will remain intact and will not require replacement. And this is a significant cost savings.

If any protective device breaks down, the consumers supplied through it are switched off. If the RCD is faulty, its circuits can be temporarily bypassed and power supplied through the circuit breaker. But when the automatic transmission is faulty, this will not work. It will need to be replaced with a new one or the circuit breaker will need to be delivered for some time.

Working conditions in different situations

The circuit for monitoring leakage currents in RCDs and differential circuit breakers can be made on different element bases using:

electromechanical relay design that does not require an additional power source for logic operation;

electronic or microprocessor technologies that require a power supply and stabilized voltage from it.

They operate identically in the normal state of suitable voltage circuits. But, as soon as a malfunction occurs in the circuit, for example, the contact of one of the wires, say zero, is broken, they will be immediately visible. They work better and more reliably in an outdated two-wire circuit.

Determining the reason for protection shutdown

After the RCD is triggered, it is immediately clear that leakage currents have arisen in the circuit and it is necessary to check the insulation resistance of the protected area.

When the circuit breaker has tripped, the reason lies in an overload of the circuit or a short circuit that has occurred.

But after turning off the differential circuit breaker of most models, you will have to spend more time searching for the reason for its removal of voltage and dealing with both the insulation resistance of the electrical wiring and the loads created inside the circuit. It is impossible to immediately determine the cause.

However, now it is possible to use expensive designs of difavtomats with alarm indicators when a certain type of protection is triggered.

Differences in markings on the body

Despite the identical appearance of the RCD and the difavtomat (identical body, “Test” button, manual switch lever, similar terminal blocks for installing wires), it is quite easy to understand them using the diagrams and inscriptions made on their front side.

The device labels always indicate the rated values ​​of its load and the controlled leakage current, the operating voltage in the electrical wiring, and the internal connection of the elements.

For both devices, the diagrams show the differential current transformer and the circuits it controls. The residual current device does not have circuit breaker current protections and they are not displayed. And they are shown on the body of the automatic rifle.

Devices from domestic manufacturers are labeled so that the buyer can easily navigate the selected models. Right on the cases you can see the inscription “Difavtomat” in a visible place. The marking “UZO” is found on the back wall.

The designation “VD” on the sign informs us that in front of us differential switch(correct technical name), which reacts exclusively to leakage currents and does not protect against overcurrent and short circuit. They mark the RCD.

The inscription "RCBO" (residual current circuit breaker) begins with the letter “A” and emphasizes the presence of circuit breaker functions. This is how difatomat is designated in technical documentation.

Residual current device (RCD) - will turn off the electricity if you touch a bare wire with your hand, if the cable insulation begins to “break through”. But it will not protect the wiring at all from short circuits or overloads; for this you need a circuit breaker (circuit breaker). The difavtomat combines the functions of an ouzo and an automatic machine. What to choose, ouzo + automatic or difavtomatic and how to distinguish them?

How to distinguish an RCD from a difavtomat

1. Direct indication of the manufacturer. Sometimes “Difavtomat” or “UZO” is written directly on the body

   Inscription difavtomat RCD inscription
   

2. Marking. If there is marking in Russian, for example from manufacturers IEK and EKF, then the letters “VD” (differential circuit breaker) indicate that this is an RCD, and the letters “AVDT” (residual current circuit breaker) or “AD” (residual current circuit breaker) ) – difavtomat.

   The letters AVDT means difavtomat VD means RCD
   

3. Current strength. On the front of the case, the largest numbers indicate the rated current. If there are no letters in front of these numbers, then this is an RCD. The letters “A”, “B”, “C” and “D” in front of the current strength indicate the type of thermal and electromagnetic release, which means this is a difautomatic device.
4. Scheme. RCDs and automatic circuit breakers sometimes have a diagram on the body. For the most part they are similar, but the automatic circuit breaker additionally contains a thermal and electromagnetic release.

   Scheme on the difavtomat
   RCD diagram
   

Connection

In the distribution panel, the RCD is connected together with a single-line circuit breaker (automatic) according to the proposed scheme:

Connection diagram for RCD and circuit breaker in the panel

In such a scheme, in the event of an electrical leak (for example, if the insulation in washing machine) the RCD is triggered, and if a short circuit or overload occurs, the machine is triggered. Several advantages of this connection:

1. A separate device always performs functions better than a combined one, therefore a combination of RCD + automatic device will always work more reliably than a differential automatic device.
2. Several circuit breakers can be connected to one RCD. For example, according to this scheme: In it, each of the machines will operate in the event of a short circuit or overload, and the RCD will operate if there is a leak in the network.
3. When triggered, it is clear what caused the shutdown - overload/short or leak. Accordingly, finding the cause of the malfunction becomes much easier.

The difavtomat contains an automatic machine and an RCD in one housing. In this regard, it has only one advantage - it takes up less space in the panel, and even then, only if you decide to connect the entire room to one machine.

Which is better RCD + automatic or difavtomatic, let's look at the diagram

Let's consider a typical connection problem in an apartment. Kitchen connection:

• Circuit of sockets;
• Lighting circuit;
• Instantaneous water heater;
• Electric hob;
• Electric oven;
• Air conditioner.

For each of these circuits in the panel it is necessary to equip a separate machine. It is also necessary to protect the kitchen from leaks, because... This is a room where water is used and there is a possibility of flooding from above.

Let's calculate the spaces occupied on the DIN rail in the case of using RCDs + automatic circuit breakers:

RCD with automatic machines

Now let’s solve the same problem using differential automata:

Automats on rack

As can be seen from the diagram, in fact, in real conditions, a difavtomatic device takes up more space than an RCD + automatic device.

Price

Let's calculate how much money you will have to spend on the above schemes. For convenience, we use the cost of equipment from ABB:

Calculating the cost of RCD equipment + automatic machines

Now we’ll do the same calculations for using difautomatic machines:

Calculating the cost of difavtomats

It turns out that using automatic devices is three times more expensive than using a combination of RCDs + automatic devices.

Replacement

No matter how reliable the equipment is, it breaks down over time. In the case of RCDs, automatic machines and automatic devices, there is no point in repairing the devices themselves - they are replaced entirely. If the machine breaks down, the replacement cost will be $2.15 + electrician services.

Inside the case of the automatic machine there is the same electromagnetic and temperature automatic device. Within the same manufacturer, the quality of the parts is identical, therefore the probability of a circuit breaker costing $2.15 breaking is the same as a circuit breaker costing $31. Therefore, the advantage, again, goes to the RCD + automatic combination.

What to choose, RCD or differential circuit breaker?

It turns out that the difavtomat has two advantages over the RCD + automatic combination:

1. Cheaper;
2. Saves space on the DIN rail;

But these advantages appear only when forming a simple circuit where only one switch is used in the panel. Which happens very rarely. In other cases, using a combination of automatic and RCD is better than a differential automatic.

Video. Advantages of RCDs and automatic devices.

The video clearly shows the differences between connecting an RCD+automatic and a difavtomatic, and describes the pros and cons of both solutions.

The electrical safety of your own home worries any apartment owner, and the technical terminology of protective modules is so confusing that an uninitiated person can easily make a mistake when choosing them.

For example, the names “Differential switch” and “Automatic differential switch” sound approximately the same, but they contain a huge difference.

In the article, I explain in detail how an RCD differs from a difavtomat in simple words for a novice home craftsman.

How to distinguish an RCD, a difavtomat and a circuit breaker by purpose: the most important principle

All three protective modules have approximately the same appearance, dimensions, and method of mounting on a Din rail. This is the result of equipment unification. They are united by the common principle that they control the current parameters and are designed to save a person and his property from its effects.

However, they perform different tasks. I will explain them briefly in three paragraphs.

Electric current in home network moves in a closed circuit in the direction that the person gave it, connecting the household appliance to the voltage circuits. In this case, useful work is done.

The magnitude of the current depends on the resistance applied to the voltage and must be maintained at the nominal value and not go beyond the designated area of ​​the electrical circuit. In this case, any device works normally.

But in our lives there are many unforeseen accidents, when a person makes a mistake or the insulation is damaged, its resistance decreases. In this case, the current flows in another direction or increases to a dangerous value, which requires emergency measures.

This task is performed by security modules using their own algorithms.

How a residual current device works: a brief explanation

The RCD is designed to control the direction of current flow according to the circuit intended for it. It cuts off the voltage from the area being stripped if a leak forms through damaged insulation.

The residual current device is mounted and.

In simple words: if a person accidentally touched the phase potential and went through his body electricity, then the RCD is obliged to prevent an emergency situation as quickly as possible and save the victim.

For this purpose, it includes a phase comparison organ - a differential transformer. It constantly monitors the vectors of currents flowing along the input phase wire and the outgoing zero wire.

If the circuit insulation is normal, then there will be no leakage to the side, and both vectors will be balanced. The RCD allows the circuit to continue to operate normally.

As soon as the differential transformer detects an imbalance of vectors, the voltage is immediately turned off.

Due to this principle, the RCD is officially called a “Differential Switch”. Remember this term well. This module does not perform any other functions other than combating leaks, and if the current increases above the rated value, it can burn out; it itself needs such protection.

Circuit breaker: module protective functions

The machine is also mounted at the input of the circuit in the panel. It controls the amount, not the direction, of current flowing through it. When it begins to exceed the nominal value, the circuit is broken by a power contact.

The value of the emergency current can be either small or very dangerous. At values ​​up to 1.13 rated load the machine does not work. Such regimes are created for a short time and usually disappear on their own.

The switchable overload zone starts from this boundary and consists of two sections:

1. thermal release;
2. electromagnetic cut-off.

The speed of eliminating an emergency situation, as shown by the time-current characteristic, depends on the magnitude of the overload. The higher it is, the faster the shutdown occurs.

The thermal release operates on the thermal deformation of the bimetallic plate due to its bending.

Current cutoff is provided by a shutdown electromagnet.

Both machine protections knock out a pin that secures the power contact spring, which breaks the emergency current flow chain.

Set it up yourself, connect it, because it can also burn out.

An automatic circuit breaker is a necessary protection attribute for an RCD. It always complements the differential switch in the circuit. They are placed sequentially one after another.

What protection does the difavtomat provide in home wiring?

This module is intended to replace an RCD with a circuit breaker and combines their joint functions.

Its internal circuit in its design has:

1. differential organ;
2. thermal release;
3. cut-off electromagnet coil.

The combined presence of these three elements in one housing allows the use of one protective module instead of two separate ones. Manufacturers package them in such a way that they take up little space, being located in one block.

Thus, in terms of purpose, a difavtomat differs from an RCD in that it simultaneously combines the functions of a circuit breaker. It works autonomously, and the RCD is used only in conjunction with the machine.

Due to the built-in circuit breaker selected according to its ratings, the choice is made in the housing, and space is saved in the apartment panel.

External differences between RCD and difavtomat modules: 3 principles

Based on the general appearance of the case and the inscriptions on it, any buyer can evaluate the protection being purchased right in the store. To do this, the following are applied to it:

1. rated current values;
2. fundamental internal electrical diagram;
3. special inscriptions and designations.

Difference in rated current markings on the front side

The designation of the range of working loads on the front panel of the RCD and the automatic circuit breaker is a mandatory element. They are performed in different ways.

For a residual current device, it is customary to write down a digital expression of the rated current value, showing the abbreviation of the unit of measurement “Ampere” with the letter A.

I show all this in a photograph of the hager module, where I highlighted the inscription 40 A in a blue frame.

Leakage currents are indicated in milliamps.

The differential circuit breaker, like the circuit breaker included in its design, is selected not only by the rated current, but also by the type of time-current characteristic.

This allows optimal use of protection with different types equipment.

Indeed, simple resistive loads can operate in the connected circuit, for example, lighting lamps and heating elements (class B, zone 3-5 I/In) or electrical appliances or machines with electric motors with increased inductive components of reactance (group D, zone 10-20 I/In).

The latter create complex transient processes when turned on and require adjustment of the protection for this period.

All this is indicated when marking the rated current of the difavtomat with the letter of the time-current characteristic class and the digital expression of the rated load.

For a specific ABB automatic circuit breaker, designed to operate with a load of sixteen amperes and class C, the designation looks like this: C16.

Thus, an RCD can be identified by the number of the rated current and the capital letter A, and a difavtomat - by the class marking and the current value.

What elements are shown on the body diagram?

All modules show a circuit diagram of the protection with controls.

The residual current device has only a phase comparison element, shown by an ellipse indicating the magnetic circuit of the current transformer with the wires inserted into it.

It involves the module triggering when leaks occur.

The difavtomat also has it in the diagram, but additionally a thermal release with a current cut-off is shown. See their icons in the photo and explanatory notes next to them:

• t° (temperature rise and overload);
• I> (inrush and current cut-off).

The presence of overcurrent and short circuit protection designations on the diagram is a distinctive feature of a differential circuit breaker.

Inscriptions and designations of modules

Here you need to look at the technical documentation. The residual current device is officially called a differential switch (abbreviation VD), which is very similar to a differential circuit breaker. But there is no need to be confused.

The latter is officially called “Automatic differential switch”, adding the word “Automatic” to the first term. In this case, the abbreviation in capital letters AVDT is used (stands for automatic circuit breaker with differential current).

In fact, remembering all this is easy. It is enough to remember that the RCD includes only a differential element, and the differential device has added circuit breaker protection. That's all.

The abbreviation VD and AVDT, other information besides the side of the front panel can be engraved on the side. Just turn the case and see this information.

But here manufacturers act at their own discretion. They may not engage in such labeling, which is typical for foreign companies.

Cost of protection

Comparing the price of these two modules with each other is a ignoble matter: you can make a mistake. But a general trend in this matter is still visible.

For analysis, it is necessary to consider samples from the same manufacturer with equivalent parameters.

For example, if you buy a residual current device with rated current at 16 amperes and a leakage setting of 30 mA, then select the appropriate machine for it for the next rating of the standard current scale of 20 A from the same manufacturer.

Add up their costs and get a sum that must be compared with the price of the automatic differential switch. You will see that the latter will cost you a little more.

If you need to install several automatic machines, the difference in the total purchase price can reach a noticeable value.

I give advice: if there is a budget deficit, you can save on the cost of modules by purchasing and installing one RCD for several groups of consumers united by outgoing lines.

In such a situation, it is enough to separate these lines with automatic switches, as shown in the picture below.

However, this connection scheme is fraught with a hidden drawback: if there is a current leak on one of the lines, the RCD will turn off, and they will all have to be checked one by one, which will take more time.

If we talk about the reliability and maintainability of the “UZO + Automatic” or Difavtomat circuits, then it should be taken into account that the breakdown of any of the first two modules will result in a cheaper purchase than in the second case.

Summary table of distinctive characteristics of modules

For simplicity and brevity, I have summarized all my information in a table comparing the characteristics of the protections under consideration.

For those who want to additionally watch a video on this topic, I recommend the work of the owner of “Electrician’s Notes.” Be sure to read the questions with comments below.

To what extent I was able to explain the difference between an RCD and a difavtomat in simple words is up to you to decide. Therefore, I look forward to your comments or questions on the topic.

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