To solve the problem of protecting the wiring from overloads and leakage currents, you can use a pair of devices - a circuit breaker and RCD. But the same problem is solved by a differential circuit breaker, which combines both these devices in a single package. About the correct connection difavtomata and his choice and will be discussed further.

Purpose, specifications and selection

The content of the article

• 1 Purpose, specifications and selection
  • 1.1 Characteristics and selection
    • 1.1.1 rated current
    • 1.1.2 Time-current characteristic or type of electromagnetic release
    • 1.1.3 Rated voltage and mains frequency
    • 1.1.4 Rated breaking differential current or leakage current (setpoints)
    • 1.1.5 Differential protection class
    • 1.1.6 rated breaking capacity
    • 1.1.7 Current Limit Class
    • 1.1.8 Temperature conditions of use
    • 1.1.9 Availability of markers about the cause of the drawdown
    • 1.1.10 Type of design
  • 1.2 Manufacturer and price
• 2 How to connect difavtomat
  • 2.1 Electrical connection
  • 2.2 Functional check
• 3 Schemes
  • 3.1 Simple layout
  • 3.2 Better protection
  • 3.3 Selective schemes
• 4 Basic connection errors

A differential or differential circuit breaker combines the functions of a circuit breaker and RCD. That is, this device alone protects the wiring from overloads, short circuits and leakage currents. The leakage current is generated when a malfunction of the insulation or when touching the current-carrying elements, that is, it still protects the person from being hit by electricity.

Difavtomats are installed in electrical distribution panels, most often on din-rail. They are put instead of a bunch of automatic + UZO, physically take a little less space. How specifically - depends on the manufacturer and type of performance. And this is their main plus, which can be claimed when upgrading the network, when the space in the panel is limited, and you need to connect a certain number of new lines.

Difavtomaty are used to protect the wiring from increased loads and people from electric shock

The second positive point is cost savings. Typically, a difavtomat costs less than a pair of automatic + UZO with similar characteristics. Another positive point is that it is necessary to determine only the nominal value of the circuit breaker, and the RCD is built in by default with the required characteristics.

There are also disadvantages: when you exit and fail one of the parts of the difavtomat, you will have to change the whole device, and this is more expensive. Also, not all models are equipped with flags, which can be used to determine why the device triggered - due to overload or leakage current - which is of fundamental importance when figuring out the reasons.

Characteristics and selection

Since the difavtomat combines two devices, it has the characteristics of both of them and when choosing, it is necessary to take everything into account. Let us see what these characteristics mean and how to choose a differential automaton.

Designation of difavtomat on schemes

Rated current

This is the maximum current that the machine can withstand for a long time without loss of performance. Usually it is indicated on the front panel. Rated currents are standardized and can be 6 A, 10 A, 16 A, 20 A, 25 A, 32 A, 40 A, 50 A, 63A.

Four-pole difavtomat to connect to the network 380 V

Small denominations - 10 A and 16 A - are placed on the lighting lines, medium ones - on powerful consumers and outlet groups, and powerful - 40 A and above - are mainly used as an introductory (common) difavtomat. It is selected depending on the cable cross-section, just like when choosing the rating of the circuit breaker.

Time-current characteristic or type of electromagnetic release

It is displayed next to the nominal value, indicated by the Latin letters B, C, D. It indicates what overloads with respect to the nominal the automatic switch-off occurs (to ignore short-term starting currents).

Diphiftomat nominal and its time-current characteristic

Category B - if the current is exceeded by 3-5 times, C - when the nominal is exceeded by 5-10 times, type D is disconnected at loads that exceed the nominal value by 10-20 times. Type C apartments are usually placed in apartments, B in rural areas can be placed, in enterprises with powerful equipment and large starting currents - D.

Rated voltage and network frequency

For which networks the device is intended - 220 V and 380 V, with a frequency of 50 Hz. There are no others in our trading network, but still, it’s worth checking out.

Voltage and frequency for which the differential circuit breaker is designed

Differential automata can have double labeling - 230/400 V. This suggests that this device can work in the network for 220 V and 380 V. In three-phase networks, such devices are put on outlet groups or on individual consumers, where used only one of the phases.

As water difavtomats on three-phase networks, devices with four inputs are necessary, and they differ significantly in size. It is impossible to confuse them.

Nominal tripping differential current or leakage current (setpoints)

Displays the sensitivity of the device to the resulting leakage currents and shows under what conditions the protection will work. In everyday life, only two ratings are used: 10 mA for installation on a line in which only one powerful device or consumer is installed, which combines two dangerous factors - electricity and water (a flowing or storage electric water heater, a cooking surface, an oven, a dishwasher and etc.).

For lines with a group of sockets and outdoor lighting, difavtomats are installed with a leakage current of 30 mA, they are not usually placed on the lighting lines inside the house - for economy.

Leakage current or settings on differential machine

The device can be written simply in milliamperes (as in the photo on the left) or the letter of the current setting (in the photo on the right), followed by numerals in amperes (at 10 mA, 0.01 A, at 30 mA, 0 , 03 A).

Differential protection class

Displays from what type of leakage current protects this device. There is a letter and graphic image. Usually put an icon, but maybe a letter (see table).

Letter designation	Graphic designation	Decryption	Application area
Au		Responds to alternating sinusoidal current	Put on the line, which is connected to a simple technique without electronic control
BUT		Reacts to sinusoidal alternating current and pulsating DC	It is applied on lines from which the equipment with electronic control is powered
AT		Captures variable, impulse, constant and smoothed constant.	Mainly used in production with a large number of various equipment.
S		With shutdown time delay 200-300 ms	In complex schemes
G		With shutdown time delay of 60-80 ms	In complex schemes

The choice of differential protection class difavtomata is based on the type of load. If it is a microprocessor-based technique, class A is needed, AC class is suitable for lighting or powering simple devices. Class B in private houses and apartments are rarely placed - there is no need to “catch” all types of leakage currents. Connecting a class S and G difavtomat makes sense in multilevel protection schemes. They are set as input if there are other differential disconnect devices in the circuit. In this case, when one of the downstream leakages triggers, the input will not turn off and the healthy lines will be in operation.

Rated breaking capacity

Shows what current is able to disable the differential when a fault occurs and stay healthy. There are several standard values: 3000 A, 4500 A, 6000 A, 10 000 A.

Breaking capacity diphiftomata

Выбор дифавтомата по этому параметру зависит от типа сети и от дальности расположения подстанции. В квартирах и домах на достаточном удалении от подстанции используют дифавтоматы с отключающей способностью 6 000 А, близко к подстанциям ставят на 10 000 А. В сельской местности, при подводе электропитания по воздушке и в давно не модернизированных сетях достаточно 4 500 А.

На корпусе эта цифра указана в квадратной рамке. Местоположение надписи может быть разным — зависит от производителя.

Класс токоограничения

Чтобы ток короткого замыкания принял максимальное значение, должно пройти какое-то время. Чем быстрее будет отключено электропитание от поврежденной линии, тем меньше меньше вероятность получения повреждений. Класс токоограничения отображается цифрами от 1 до 3. Третий класс — отключает линию быстрее всего. Так что выбор дифавтомата по этому признаку прост — желательно использовать устройства третьего класса, но они дороги, зато дольше остаются работоспособными. Так что при наличии финансовой возможности, ставьте дифавтоматы этого класса.

Токоограничение дифавтомата

На корпусе эта характеристика изображена в маленькой квадратной рамке рядом с номинальной отключающей способностью. Она может стоять справа (у Legranda) или снизу (у большинства других производителей). Если вы такой отметки не нашли ни на корпусе, ни в паспорте, значит этот автомат не имеет тоокограничения.

Температурный режим использования

Большинство дифференциальных защитных автоматов рассчитаны на работу в помещениях. Они могут эксплуатироваться при температурах от -5°C до + 35°C. В этом случае на корпусе ничего не ставят.

Обозначение повышенной морозостойкости дифавтомата

Иногда щитки стоят на улице и обычные защитные устройства не подойдут. Для таких случаев выпускаются дифавтоматы с более широким диапазоном температур — от -25°C до +40°C. В этом случае на корпусе ставят специальный знак, который немного похож на звездочку.

The presence of markers on the cause of the drawdown

Not all electricians like to install dihavtomatas, because they believe that a bunch of protective circuit breaker + RCD is more reliable. The second reason - if the device works, it is impossible to determine what caused that - overload, and you just need to turn off some device, or leakage current, and you need to look for where and what happened.

In order to solve at least the second problem, manufacturers began to make flags that indicate the cause of the drawdown of the difavtomat. In some models, this is a small platform, the position of which determines the cause of the shutdown.

A checkbox that indicates the reason for the trip.

If the shutdown caused an overload, the indicator remains flush with the case, as well as the photo on the right. If the difavtomat worked in the presence of a leakage current, the flag appears at some distance from the case.

Type of design

There are two types of automatic machines: electromechanical or electronic. Electromechanical more reliable, as they remain operable even when power is lost. That is, if the phase disappears, they will be able to trigger and disable also zero. Electronic work requires power supply, which is taken from the phase wire and loses its working capacity when the phase is lost.

Manufacturer and price

Electricity is not worth saving, especially on devices that provide protection for wiring and life. Therefore, it is recommended to always buy components from well-known manufacturers. The market leader is Legrand (Legrand) and Schneider (Schneider), Hager (Hager), but their products are expensive, and there are a lot of fakes. Not so high prices for IEK (IEK), ABB (ABB), but there are more problems with nm. In this case, it is better not to get involved with unknown manufacturers, as they are often simply unworkable.

The choice is actually not that small, even if we confine ourselves to only these five firms. Each manufacturer has several lines, which differ in price, and significantly. To understand the difference, you must carefully look at the technical characteristics. Each one influences the price, so carefully read all the data before purchasing.

How to connect difavtomat

Let's start with the methods of installation and connection of conductors. Everything is very simple, there are no special difficulties. In most cases, it is mounted on a dinrake. To do this, there are special projections that hold the device in place.

Dinriku mount

Electrical connection

Connection of the power supply unit to the power grid is made by wires in isolation. Section is selected on the basis of nominal. Usually the line (power supply) is connected to the upper sockets - they are signed with odd numbers, the load - at the lower ones - are signed with even numbers. Since both the phase and zero are connected to the differential automaton so as not to be confused, the sockets for the “zero” are signed with the Latin letter N.

Connection diagram difavtomata usually on the body

In some lines, you can connect the line to both the upper and lower slots. An example of such a device in the photo above (left). In this case, the numbering is written in the scheme through a fraction - 1/2 at the top and 2/1 at the bottom, 3/4 at the top and 4/3 at the bottom. This means that it does not matter to connect the line from above or below.

Connecting the difavtomat on the distribution board

Before connecting the line, the wires are removed from the insulation at a distance of about 8-10 mm from the edge. At the desired terminal slightly loosen the mounting screw, insert the conductor, tighten the screw with a sufficiently large force. Then pull the wire several times to make sure the contact is normal.

Health check

After you have connected the unit, supplied power, you need to check the operation of the system and the installation. First we test the unit itself. To do this, there is a special button, signed by “Test” or simply by the letter T. After the switches are turned on, we press this button. In this case, the device must "knock out". This button artificially creates a leakage current, so we checked the performance of the typing machine. If there was no triggering - it is necessary to check the correctness of the connection, if everything is correct, the device is faulty

If by pressing the "T" button the dialpad works, it is operational

A further check is to connect a simple load to each outlet. This will check the correctness of the disconnection of the outlet groups. And the last thing is the alternate switching on of household appliances, to which separate power lines are installed.

Scheme

When developing a wiring diagram in an apartment or house there may be many options. They can differ in convenience and reliability of operation, degree of protection. There are simple options that require a minimum of costs. They are usually implemented in small networks. For example, in country houses, in small apartments with a small amount of household appliances. In most cases, you have to install a large number of devices that ensure the safety of wiring and protect against electric shocks.

Schemes come in different levels of complexity.

Simple circuit

It does not always make sense to install a large number of protective devices. For example, in the summer cottage where there are only a few sockets and lighting, it is enough to put only one difavtomat at the entrance, from which separate lines will go to groups of consumers — sockets and lighting.

A simple wiring diagram for a diphiftomat on a small network

This scheme does not require large expenditures, but when leakage current appears on any of the lines, the difavtomat will work, de-energizing everything. Until clarification and elimination of the causes of light will not.

More reliable protection

As already mentioned, individual diphavomats put on “wet” groups. These include the kitchen, bathroom, outdoor lighting, as well as appliances that use water (except for the washing machine). This way of building a system gives a higher degree of security and better protects the wiring, equipment and people.

More sophisticated and reliable scheme: connecting a difavtomate to every potentially dangerous device

The implementation of this method of wiring devices will require large material costs, but the system will work more reliably and stably. Since when one of the protective devices triggers, the rest will remain operational. Such a connection difavtomata used in most apartments and small houses.

Selective schemes

In extensive power supply networks, the need arises to make the system even more complex and expensive. In this version, after the counter, an input differential automat of class S or G is installed. Then, each group has its own automaton, and if necessary it is also placed on individual consumers. See the connection for this case in the photo below.

Selective installation scheme

With this construction of the system, when one of the linear devices triggers, all the rest will remain in operation, since the input automatic differential shutdown device has a delay in response.

Basic connection errors

Sometimes after connecting a difavtomat it does not turn on or is cut down when any load is connected. That means something is wrong. There are a few common mistakes that occur when assembling a dashboard yourself:

• The wires of the protective zero (earth) and working zero (neutral) are somewhere united. With such an error, the difavtomat does not turn on at all - the levers are not fixed in the upper position. We'll have to look for where the "earth" and "zero" are combined or confused.
• Sometimes when connecting a difavtomat zero to a load or to lower located automata, it is taken not from the device output, but directly from the zero bus. In this case, the circuit breakers are in working position, but when you try to connect the load, they instantly turn off.
• From the output of the difavtomat, zero is not supplied to the load, but goes back to the bus. Zero load is also taken from the bus. In this case, the knife switches are in the working position, but the "Test" button does not work and when you try to turn on the load, the shutdown occurs.
• Mixed zero connection. From the zero bus, the wire must go to the appropriate input, denoted by the letter N, which is at the top, not down. From the bottom zero the wire should go to the load. Symptoms are similar: the switches are turned on, the “Test” does not work, the load is activated when the load is connected.
• In the presence of two difavtomats in the circuit, the neutral wires are confused. With such an error, both devices are turned on, “Test” works on both devices, but when any load is turned on, both automata are knocked out at once.
• In the presence of two difavtomatov, the zeros going from them somewhere further connected. In this case, both machines are cocked, but when you click on the "test" button of one of them, two devices are cut down at once. A similar situation occurs when turning on any load.

Now you can not only choose and connect a differential circuit breaker, but also understand why he knocks out exactly what went wrong and correct the situation on his own.