Differential circuit breaker is different from ouzo. Automatic or differential machine: how to distinguish and what to choose

The profession of an electrician is accompanied by a fairly wide range of folklore jokes, such as “current does not kill its own”, as well as prejudices and delusions. The latter include confusion in the definition of an RCD and a difavtomat, which arose due to the fact that both of these devices automatically turn off the network. In fact, the difference between an RCD and a difavtomat is of a fundamental nature, which must be taken into account when constructing power supply circuits and repairing them.

Emergency disconnection of consumers from the power grid is carried out automatically in the event of:

short circuit in the circuit (overcurrent protection);
overheating of conductors during overloads due to short circuit or excessive power consumption, as well as the lack of the necessary contact density;
leakage currents due to a decrease in insulation resistance or direct contact with one of the phases.

These cases have different physical nature. Therefore, a universal discrete device that takes them into account simultaneously does not exist. The design of the protective device may include a sensitive element of the same type or a set of them in different combinations.

Operating overloads occur, for example, during the operation of electric motors. To protect them, thermal relays are installed in the electric drive control circuit, in which bimetallic plates are usually made the working body.

Leakage currents are recorded by differential transformers, in the secondary winding of which current occurs when a phase imbalance occurs in the network conductors. The working body is a power relay that opens the contacts. RCD works on this principle.

Overcurrents are characterized by a sharp increase in the strength of electromagnetic induction. To respond to this factor, a solenoid with a moving core is installed in the circuit breakers, which, at a critical current strength, shifts and opens the contacts. Overcurrents also cause heating, therefore, a bimetallic plate is placed in series with the solenoid in the same case. Get a circuit breaker that takes into account two emergency factors.

If, however, a solenoid with a moving core, a bimetallic plate and a differential transformer are placed in the body of the protective device, then it will respond to all three emergency cases. This is how the RCD differs from the difavtomat - the number of influences to which the device reacts.

Universality or specialization?

So, which is better - RCD or difavtomat? If an electrician has the task of simplifying his work and fulfilling all the requirements of the "Rules for the operation of electrical installations of consumers" at a time, then the universal device is just what he needs.

For example, when zero burns out, you don’t have to worry about the fact that in some of the apartments consumers will have a voltage of 380 instead of the prescribed 220 volts. In this case, a conventional automatic switch will work no earlier than in an hour - the time during which the heating of the conductors reaches a critical level. And the difavtomat, if it is of an electromechanical type, will turn off the emergency network within milliseconds.

The use of a protective device with three sensing elements has the following advantages:

response to all types of emergencies;
installation is simplified - there is no need to connect devices with jumpers;
saves space in the switchboard.

It also has disadvantages:

during an emergency shutdown of the network, you cannot unambiguously say whether it was a short circuit, a zero break, or a partial breakdown of the insulation;
the more elements in the device, the lower its reliability. This is a general technical rule;
a conflict between the individual elements of the device is not ruled out, as a result of which the overall efficiency of the difavtomat is lower than that of a highly specialized device.

The placement of devices for protection against overheating, short circuit and leakage current in one housing also conflicts with where such devices should be installed if they were autonomous. Circuit breakers are best placed at the nodal points of the network. And the RCD, on the contrary, is as close as possible to the consumer, since each meter of the conductor is a resistance that can extinguish the differential current that occurs when the insulation resistance is violated or if live parts are accidentally touched.

As a result, we can say the following: if you install circuit breakers to ensure the overall performance of the network and protect the devices included in it, then the difavtomat is definitely better. Choose highly specialized RCDs, with the aim of ensuring the safety of your own or all those living in the house.

How to distinguish one from the other

Not all sales consultants can unequivocally answer what type of protective device they offer - an RCD or a differential machine. Yes, and on emergency calls you have to meet with unfamiliar schemes. Therefore, the question of how to distinguish an RCD from a difavtomat is very acute.

Visually, these devices are distinguished by three features:

Now you know what is the difference between an RCD and a difavtomat - both in physical essence and external. This will help you both in drawing up a power supply scheme and in repairing it.

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

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

We offer to understand the functional features of switching devices, and find out in what situation, what is better 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 you have to use on a daily basis. 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 phenomena:

leakage currents;

short circuits.

An overload can be encountered if you use new powerful equipment in an apartment with old wiring. The cable does not withstand the total load, overheats, melts and fails.

A magnificent 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 contact and insulation melting, as well as fire

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

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

A short circuit, which occurs due to the unintentional connection of 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 the 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 or considered inferior and dangerous.

Load shedding switchgears

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

However, there are much more connection options, so first you need to understand the difference between an RCD and a differential machine, and then already make the installation.

Circuit breakers - modified "plugs"

When the variety of protective devices was out of the question, with excessive load on the line, “plugs” worked - the simplest emergency devices.

Their functionality was improved and received, which work 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 the case made of durable technoplastic. Outside there is a circuit closing / opening lever and a mounting groove for “landing” on a DIN rail (+)

In one switchboard there can be one or several switches, their number depends on the number of circuits serving the apartment or house.

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

Image gallery

A prerequisite for assembling a home electrical network is. The circuit breakers operate 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-place. Such models have already appeared on sale, but their cost is slightly higher than that of traditional ones.

Difficulty in wiring

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

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

The diagram shows the wiring well.

With a schedule like this:

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

With a difavtomat, the connection is much easier. Jumpers are not needed, only the phase and zero are connected to the corresponding terminals, and the outputs are sent to the load.

What does this give the installer? Facilitates the connection process, reduces the number of wires, respectively, guarantees more order on the electrical panel.

How is the operation diagnostics performed?

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

It is difficult to immediately determine the cause of the protection operation, since it can be a leakage current, a short circuit, and the total load that the wires could not cope with.

By a triggered RCD or machine, you can immediately see where to look for the cause. In the first case - an insulation problem, in the second - an increased load or short circuit. The latter can be determined by additional features

If a difavtomat reacted to a network failure, then the cause will have to be looked for longer. It is necessary to check all versions, and this will take more time and effort.

What appliances are cheaper to buy and fix?

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 is characterized by a higher price. In fact, everything is different: a universal difavtomat costs a round sum, and 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 difautomatic 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 grows. If for one circuit the purchase of a RCBO is only 1 thousand rubles more expensive, then for five circuits the difference in amounts grows to 5 thousand rubles.

Thus, both difautomats and RCD units with automatic switches 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 navigate the protection devices and choose the right solution depending on the situation, we suggest watching thematic videos.

Interesting information about the principle of operation and installation of RCDs:

A few tips from a professional electrician:

What played a role in choosing a difavtomat:

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

Have something to add, or have questions about the topic? You can leave comments on the publication, participate in discussions and share your own experience in using RCDs and a differential machine. The contact block is below.

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

RCD, in simple terms, is a protected shutdown device installed in apartments and in places with the risk of a sudden change in electrical voltage. The advantages and functions of this device include the ability to recognize the difference and strength of the current. In the case when there is an increase in the current passing through the device, the system simply opens the network, which allows you to stop the 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.

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

Differential circuit breaker

This device contains thermal and modular protection, which creates the maximum comprehensive security against all possible dysfunctions.

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 directly at the moment of risk and the occurrence of a short circuit. The design of the device plays the role of a power relay in the electricity circuit.

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

Having put yourself before the choice of what is best for ensuring safety in a residential area, an RCD or a difavtomat, you need to understand the existing difference:

firstly, the basic equipment of the RCD differs from the basic differential machine in that it attracts a protective function only in case of overvoltage in the wiring or current leakage.
Secondly, a differential type device, although it performs a similar task, also serves as protection against short circuits.
The standard residual current device has a single module that only detects the difference in current.
In the opposite machine there are thermal and electromagnetic releases of networks.

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

In case of purchase, it is important to consider that a differential system will cost significantly more than a conventional protective device.

Switch automatic modular 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 right on its body.

The main technical characteristics of difavtomatov are considered the same as the residual current devices, the manufacturer indicates them on the front panel. Let's consider each indicator separately.

Rated current is the current in amps that the device can carry for a long time, its values have the same standards as for circuit breakers. Within the range it can be from 8 to 52 amperes.

The time-current characteristic is 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 machine. Thus, if any letter is indicated before the designation of the rated current, therefore, this is a difavtomat. If this is a number, then the device is considered a conventional RCD.

A simple difavtomat

Rated residual breaking current - standard values 10, 20, 30, 100, 300, 500 mA. These can be used to protect against electric shock to a person or as a stabilizer and apparatus that prevents a fire.

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 - 380 V. Consider the subtleties and additional functionality:

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

Technical characteristics of the RCD

For the correct orientation and decision on the choice of RCD or differential machine, it's time to discuss the technical features of residual current devices that have a basic package.

Each characteristic of the device is indicated on its body, and a trade mark or manufacturer's brand may also be indicated here. Basically, the designation of the characteristics on the RCD is similar to the previous device, the only difference in this is the different values. All main characteristics are given as the ability of the device to be in working order at a temperature not exceeding +30°C.

RCDs of various 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 for shower cabins for boilers and other devices that are located in wet rooms 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 index of 30 A. Also, for a small area and one electrical network, the installation is used one RCD, in the event of a current leakage, there will be a complete de-energization of 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, it is possible to 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?

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

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

Tripping time-current characteristic

The general essence of the operation of the circuit breaker

According to the principle, the operation of such a device consists in 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 case when this force reaches the threshold on which the operation of the automatic device is based, the plate releases the springs, from which the contacts in the network are disconnected;
electromagnetic - the principle of operation of an automaton of this type is similar, the difference lies only in the presence of a coil with a magnetic middle.

Any of the varieties of these machines copes very well with their tasks, in addition, experienced electricians still cannot determine which of the devices is advisable to install in a certain type of network. In fact, we have figured out how to distinguish an RCD from a difavtomat, we have disassembled the difference between an RCD and an automaton, so this is an occasion to get close to the question of the correct choice of these devices.

Three-pole circuit breaker

Rules for a good choice: we buy an RCD, an automatic machine and a difavtomat

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

the purpose of the device, the activity of its components, to know how the design of the circuit breaker is arranged;
requires the ability to understand all the parameters of the device and be able to adjust their work;
the normative document and the method of selection of the machine are taken into account;
take into account the age and material of electrical wiring;
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 automaton and their effects in the initial work with electricity. It is important to make sure that the characteristics correspond as much as possible to the indicators for which the machine is selected, for example, the rated current of the device purchased for apartments should be marked B or C. The indicator D is set in special cases. So, first of all, the limiting current is taken into account, now the current of the machine is being considered, this indicator is no less important, it is also advisable to include the pole of the device and its ability to work here.

An example of a wiring diagram in an apartment

Important note! In addition to the main characteristics and functionality 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 the characteristics, namely:

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

Even with careful selection of these subtleties, erroneous nuances can develop.

Many inexperienced installers often make even critical mistakes when choosing. In fact, devices that would work perfectly do not exist and any RCD will have leakage, even if it can be minimal and quite far from the norm, however, it is unreasonable to leave this property unattended.

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

Based on this remark, care must be taken to ensure that the sum of the leakage indicators does not exceed 1/3 of the rated current. From this follows the conclusion - taking into account the leakage of current of a natural nature with an RCD is mandatory.

Differential machine or what to look for when choosing

Each of the devices that protect in relation to a person and a room from an electrical network has a number of characteristics, without taking into account and knowing which the choice of a device is impossible.

Firstly, this type of device for living space should be chosen, taking into account the indicator of its phase. Secondly, attention is necessarily drawn to the rated voltage. In a residential building, this figure can range from 220 V to 380 V. Consider the possibility of installed releases, the general leakage of the differential machine.

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

Testing is available to any difavtomat, therefore, before turning it on to clean work with your electrical network, pay attention to how the device behaves in test mode.

Finally, you received an extensive answer, what kind of RCDs and automatic machine are they, what is the difference between them and the principle of operation of each of them, having also familiarized yourself with the characteristics of the differential device, you can make your own choice, of course, due to competent considerations.

In one line:

DIFavtomat includes RCD as a part.

To protect the wiring and all elements of the electrical network, residual current devices (RCDs) and differential circuit breakers (difavtomats) are used. The principle of operation of these devices is not much different, but in order to ensure the most effective security, you should know what the difference is and how to choose the right device.
Content:

The design and principle of operation of the RCD

A residual current device or RCD is a switching electrical device that interrupts the supply of current when the differential current exceeds the operating value. To accomplish this task, it includes several elements that perform the tasks of measuring / comparing currents and opening / closing conductive contacts. Please note that the design of the RCD does not include elements that provide direct protection for the wiring, circuit or the device itself - it only interrupts the power.

Thus, we can name the main goals of using RCDs:

protection of electrical network users from injuries caused by electric current;
fire prevention in case of current leakage.

In both cases, the device is designed for situations where the insulating material of electrical wiring or cables becomes unusable and loses its tightness, due to which current begins to flow to the body of electrical appliances, conductive objects or flammable materials.

In the working state of the electrical network, the current passes through the sensor (transformer) and creates on its secondary winding magnetic fluxes of equal strength, compensating each other. The trip relay does not operate because the secondary current is close to zero.

As soon as a current leakage occurs, there is a difference between the values of the flows and, accordingly, the trip relay is activated.

Difamat

What is a differential machine? This is a switching protective electrical device that actually combines the RCD described above and a circuit breaker. The first of them, as we have already found out, is designed to prevent fire and electrical injuries, and the second is to protect the electrical network and the device itself from overload and short circuit. That is, the differential switch serves to ensure the integrated electrical safety of the circuit, consumers and itself.

Of course, thanks to this, the difautomatic device is a more functional device, which is characterized by such advantages as a quick response to changes in operating parameters (from 0.04 s), a long working life, the ability to work in a wide temperature range (from -25˚C to +50 C).

What is the difference

The task of distinguishing an RCD from a differential automaton can mislead many novice electrical engineers. The fact is that the principle of their work is almost the same. In addition, sometimes they are difficult to distinguish from each other even in appearance. So, let's consider in order how to distinguish an RCD from a difavtomat.

Functional differences

The difference between an RCD and a difavtomat lies in the fact that the first device cannot protect the load, circuit and consuming devices from thermal or power overload - it stops the supply of electricity only in the event of a leak. Therefore, the RCD itself requires protection, which is provided by the series connection of a circuit breaker that protects not only the circuit, but also the RCD from short circuit and overload. It, in the event of an off-design load, also interrupts the power supply. Thus, if all devices are simultaneously turned on in a network with reliable wiring, increasing the load on the cables to a dangerous one, the RCD (without a machine) will not work - the current on the secondary winding of the sensor is close to zero, which means that there is no leakage. In such a situation, not only a short circuit can occur, but also a fire in the wiring (after that, the RCD will work, but it will be too late).

The differential circuit breaker, as already mentioned, includes a circuit breaker in its design by default. Let's take the previous example: we turn on all electrical appliances, causing a peak load. When a limiting current occurs, the difavtomat will stop the current supply in order to avoid heating the wires or a short circuit. And in the case, for example, with the closure of unreliable wiring on the metal case of the plate, the RCD protective relay will work.

Therefore, it is impossible to say exactly what is better to choose to ensure electrical safety. It is necessary to base the choice on the parameters and wiring diagram of the network, the power and number of connected devices and other features. Of course, difavtomat performs much more security tasks, and therefore for highly loaded systems it will be preferable to choose it. RCD, in turn, can also serve to prevent emergencies, but for comprehensive protection, in addition to it, it is necessary to connect a circuit breaker to the circuit. Due to the lower price, it would be advisable to use them in circuits where the probability of a short circuit or overheating is the lowest.

Appearance

It may seem to an inexperienced person that difautomats and RCDs practically do not differ from each other in appearance. In fact, the difference between these devices is obvious and very easy to determine. In both cases, the device will have a “Test” button, a toggle switch, an operating diagram and various symbols, but all these elements display different information and, upon close examination, look a little different from each other:

Price

Since the difavtomat is a structurally more complex and more functional device, the price difference between it and the RCD is significant. However, we cannot take into account only differential switches - in real conditions, for their operation, you will always need to select an additional machine. But even in such a situation, the price of one difavtomat turns out to be higher than that of a set of RCD + circuit breaker. Of course, you can find devices whose cost contradicts this pattern, but, most likely, these will be “nameless” brands with dubious quality. The use of such products is a separate risk, both financial and material.

Based on this indicator, we can say that the installation of automatic + RCD structures justifies itself not only by the cost, but also by the ease of further operation in power panels with a large number of consumer groups.

Advantages and disadvantages of each type of device

Consider the specific factors that you should rely on to select the right protective device:

Availability of space in the switchboard. This point is very important and should be considered first of all so that there is no situation when a difautomat was selected for the network parameters, but the size does not allow it to be installed in the shield. However, more often the problem is the location of a pair of RCD + machine, which takes up much more space.
Target. It is worth deciding what the device will be used for. If you need to avoid electric shock from one electrical appliance, for example, a washing machine, water heater, stove, it is best to install a differential machine. And to protect a group of lamps or sockets, the RCD is the best option. This will allow, when the power consumption of the group increases, only the circuit breaker can be replaced, and not the entire bundle.
Quality. In this case, it should be said that combined devices (difavtomatov) in an affordable price category are of lower quality than specialized devices (RCD).
Repair and service. The combination of the RCD and the machine gives some flexibility in case of failure - if one of these elements breaks down, only it will have to be replaced. A differential circuit breaker after combustion will require a complete replacement of the device.
Emergency power. In the event of an RCD failure, the possibility of network operation remains - for this it will only be necessary to connect the existing machine to the load. But if the difavtomat breaks down, it will not be possible to use electricity until the equipment is replaced.
Understanding the reasons for shutdown. In a combination of RCD + automatic machine, it will always be clear what caused the load to be disconnected from the power supply. If the RCD is knocked out, there is a leak, if the machine is an overload or short circuit. In the case of a difavtomat, it will be much more difficult to establish the exact cause of the malfunction.

Summarizing all of the above, we can conclude that the difference between difautomats and RCDs is great, but it cannot be said which device is best for your home. In order to choose protective equipment, one should rely on all of the above aspects, and, of course, when wiring an apartment or house, you can use different devices for each of the branches.
In this video, everything is clear - the machine plus RCD is calmer and more reliable.

For most people, an RCD and a difavtomat do not make a difference, however, for novice electricians or home owners, it is necessary to understand the definitions in the process of connecting electricity. In the material, we will consider the purpose of both devices and their fundamental differences in important parameters.

In the process of developing electrical networks in apartments or private houses, it is necessary to clearly understand what residual current devices and differential circuit breakers are in order to select the appropriate option for effective protection against electric shock.

Purpose of residual current devices

The devices are similar in appearance, but perform different tasks. The residual current device is triggered when a differential current occurs in the network, as a result of which a person may suffer by coming into contact with damaged equipment. When a leakage current occurs, the insulation of the electrical wiring is heated, which leads to a fire. Its main purpose is to protect against electrical shock and damage to wiring, which leads to fires.

Shutdown with RCD occurs when there is a voltage imbalance in the wires with phase and zero voltage in the connected network. This is due to damage to the insulation and leakage. Note that in buildings with old electrical wiring, fires due to ignition of the wiring occur frequently.

The second dangerous case is contact with electrical elements that should not be energized, as a result, the voltage flows through the human body. In this case, the circuit breaker will not fulfill its task, since a voltage of at least tens of amperes is required to turn off. For a person, a value from 30 mA turns out to be fatal, so the ability to turn off electricity at 10-30 mA will become a reliable protection for a person.

Note that the device does not protect against overcurrents, this is the key difference between it and the difavtomat. If a short circuit occurs in the network, the device may burn out, so it is not used on its own.

The question often arises of how to distinguish fake RCDs that do not perform their tasks and can lead to serious consequences in the case of low-quality devices. You can distinguish fakes by the inscriptions on the front side, marking and functional diagram. Original devices always contain markings and corresponding inscriptions with parameters, and they may be absent on fakes.

The purpose of the differential machine

The differential device is a universal device that combines the functions of a circuit breaker and a residual current device. This means that the difavtomat is able to protect the wiring from short circuits and overload, leakage. Therefore, speaking about how the RCD differs from the differential automaton, it should be noted the versatility of the automaton, which provides comprehensive protection.

If an extension cord is connected to one outlet, and a large number of powerful devices are included in it, then in most cases there is an overheating of the conductors, a short circuit and melting of the insulation. To prevent such situations, a difavtomat is used. The technical characteristics of the machine allow it to be used in any networks in order to avoid a significant excess of voltage with subsequent fire, since the machine de-energizes the power line in a few seconds.

The tripping speed is determined by the value by which the actual current exceeds the standard parameter. If the excess is multiple and a short circuit occurs, then the electromagnetic type release immediately trips. If the current flowing in the line exceeds the standard value by 25%, then the thermal type release is activated after an hour. The exact shutdown time is determined by the characteristics of the individual devices.

The difference between an RCD and a differential machine

Let's take a closer look at the individual technical characteristics, how the RCD differs from the universal difavtomat and how you can use the advantages of each device.

We note the main difference that the RCD does not protect the network from overload and short circuits. That is, it acts solely as an indicator by which current leakage is controlled, because in the event of damage to the insulation and the appearance of leakage, the power supply is turned off.

If all electrical appliances are connected to the network at the same time and an intentional overload is created, the protection device will not work, and the differential circuit breaker will instantly de-energize the network, preventing ignition and melting of the insulation.

When wondering what to choose - an RCD or a universal differential machine, it is necessary to consider their technical parameters and compare them with the characteristics of the network, the required tasks:

rated current marking is one of the key differences between an RCD and a difavtomat. The rated operating current and leakage current must be indicated on the case. If only one parameter is specified, this is the first device - it indicates the value of the rated current. If a letter is written in front of the number, then you have a difavtomat in front of you;
the electrical circuit on the device - the devices contain similar circuit diagrams, on the RCD diagram it is an oval denoting a differential transformer and an electromechanical relay. On the diagram of the second device, additional thermal and electromagnetic releases are applied, which protect against overload and short circuits. The schematic representation is the main difference between the RCD and the differential machine;
the name on the device case on the side - is applied not on all devices;
abbreviation on the device. To understand what is in front of you - a difavtomat or an RCD, the devices of domestic manufacturers indicate VD or AVDT.

Trying to understand the question, what is the difference between an RCD and a difavtomat, it is necessary to focus on the listed technical parameters, as well as on the cost. A high-quality difavtomat has a lower cost than a residual current device paired with a standard switch. In the selection process, we recommend paying attention to foreign manufacturers, as they are characterized by the best response time, reliability of elements and cases. The RCD is connected to protect against leakage, so choose high-quality equipment that, paired with a switch, will provide reliable protection.

It is important to note that the reliability of operation differs little, the main differences are in the operation time and the operation of two types of special releases in the difavtomat. The disadvantage of the latter is the impossibility of determining what caused the operation: network overload, short circuit or leakage.

The advantage of AVDT is the combination of two devices in its case. In the switchboard there is an additional place for a single-pole machine. However, in the event of a breakdown, a full replacement will be required. The residual current device occupies two places, since it is connected complete with the machine. This equipment simplifies the repair process in case of failure - only one element must be replaced.

When laying electrical wiring networks in an apartment or a private house, it doesn’t matter what to install - a difavtomat or a separate RCD with a circuit breaker, the question will only be in the free space in the shield. When installing in a large private house, it is necessary to calculate the potential load in advance and make a choice in favor of options that will cope in case of overloads with the available amount of household appliances.

Which device is better to choose

Before installing the wiring, it is necessary to determine the planned load, and based on the results obtained, make a choice. It is necessary to focus on the limiting current and power, based on the passport data of electricity consumers.

Here are some models that have proven themselves well among users:

Legrand in electronic-mechanical or electronic modifications;
IEK and Schneider Electric - have many advantages, are universal;
ABB 16A - instant shutdown in the event of a short circuit;
AD 12 - works in standard mode and voltage reduction to 50 V;
EKF AD 32 - often used to connect boilers in the kitchen and bathroom.

To determine the differences, you need to familiarize yourself with their characteristics and calculate the planned load in the network, the number of connected equipment and its power. With proper selection, the power grid will be reliably protected from leakage currents and overloads.