Electricity in the modern world is an indispensable source of energy. It is used in every home. To ensure that the operation of the electrical network is safe, special devices are used. Their design and operation may differ.
Automatic residual current circuit breakers are designed for industrial and domestic power networks. They have special features. Thanks to such a system, the operation of the power grid becomes simple and safe.
General characteristics
The residual current circuit breaker (RCBO) is an electromechanical type device. It is designed to protect the electrical circuit from current leakage, as well as from its overload. They also eliminate the possibility of a short circuit.
Difavtomat combines the qualities of a circuit breaker and RCD. If a person comes into contact with the wiring, the RCBO will prevent electric shock. This function is similar to RCD. If overloads are observed in the network, the device, just like the circuit breaker, will stopsupplying electricity to the circuit.
However, difavtomat has a number of differences from similar units. The design implies the presence in a small case of two devices listed above at once. The constituent elements of the presented variety of switches allow them to be used in a wide range of areas of human activity.
Design
The difference between a residual current circuit breaker and an RCD is determined primarily in the field of their design. The presented unit consists of two parts. They perform protective and control functions. The latter works in accordance with the principle of RCD. The working part that performs the control is a conventional voltage switch. It can be single, double or quadruple.
If the working part of the unit detects the presence of an electricity leak, its protective mechanism is activated. This allows you to protect household, industrial appliances, as well as a person from electric shock. A special module turns off sequentially the working and then the control part of the device.
The difference between a difavtomat and an RCD lies primarily in the ability of the presented device to protect not only a person, but also equipment from network overvoltage.
Working principle
The characteristics of automatic differential current circuit breakers allow them to be used in various types of networks. In order for the presented devices to be able to control and recognize the current in the circuit, a small transformer is built into them. This element fires when the inputand the output voltage has a different value. With equal indicators on outgoing and incoming conductors, the unit operates in normal mode.
The transformer has a core. Inside it, the current forms directed magnetic fluxes. Depending on the direction in which they move, the voltage of the secondary winding is determined. If there is a leakage of electricity, a current indicator will be observed on this coil, which will not be zero. In this case, the magnetic switch is activated.
The machine constantly compares the incoming and outgoing voltage. If the balance of the magnetic field is disturbed for some reason, the latch will work. The power goes out.
Varieties
There are different classifications of RCBOs. They can be single phase or three phase. Depending on the type of wiring, it is necessary to select the appropriate unit.
Distinguish machines according to the principle of their maximum allowable current in the network. There are AVDT 32, 25, 100, 40A. This indicator makes it clear what load the machine is designed for, the current rating in Amperes. And if it is exceeded, the machine will turn off the supply of electricity to the circuit. The rated value of the current is indicated by the letter "C". In household networks, C16 or C25 units are most often used (the condition of the wiring is taken into account).
In some cases, at the time of starting some consumers, the current may increase several times. The unit must withstand such a jump. There are three types of devices that differ in varying degrees of resistance to inrush currents. Tocategory B includes RCBOs designed for overload at the time of start-up by 3-5 times. Type C devices are designed for a starting load that is 5-10 times the working load. Category D units can withstand a 10-20 times power surge when starting.
Leak current rating and RCD characteristics
One-, four- or two-pole residual current circuit breakers have different characteristics of the built-in circuit breaker and RCD. The leakage current to which the automation reacts is indicated by the symbol "delta". The adjacent number shows the value of this indicator. Its units are milliamps (ma).
In lighting, domestic networks, automatic devices with a leakage rating of 10 to 30 mA are most often used. For group networks, devices with a presented indicator of at least 30mA are required. Introductory RCBOs can have RCDs with a rating of 100 to 300 mA.
Built-in protective equipment can be of various classes. If the RCD of the unit is of the AC type, it responds exclusively to the alternating type of current. Class A devices are designed to control direct current in devices with electronic converters. Type A is most often used in household networks.
Protection of the neutral wire
Automatic differential current circuit breaker 25A, 10A, 16A and other varieties have different characteristics of the RCD. It needs power supply. It is supplied from the input of the differential protection unit. In other words, for the protection against current leakage to work, the presence of voltage in the network is required. ATorder must be both phase and neutral wires.
If a break occurs in the "phase", the leakage is automatically excluded. But if the operation of the neutral conductor is disrupted, the RCD may not work due to the lack of power to the unit. To eliminate the possibility of such a situation, some difautomats have in their design a special block for protecting the break of the neutral wire. This is a voltage relay.
If the presented block is not in the system, it is highly recommended to install it additionally. When choosing equipment, you should check the presence of a voltage relay that allows the RCD to operate even if the neutral conductor breaks.
Producers
Experts recommend purchasing protective equipment only from trusted brands in specialized stores. The safety of users and consumers of the power grid depends on this.
Selective and non-selective devices are on sale. The first category includes equipment that disables only one circuit. The rest of the consumers will work as before. Such products include, for example, difavtomat "IEK", "Schneider Electric", "Legrand", as well as ABB.
Non-selective devices turn off all circuits connected to them. Such products are supplied to the market by EKF, DPN N Vigi trademarks. Selective varieties are more popular.
Popular varieties
In the household electrical network, selective varieties of devices are most often used. They have the letter"S". One of the most popular in our country are models of ABB differential current circuit breakers. The cost of a single-pole device 16A is about 1800-1900 rubles
Company "Legrand" presents on the market devices of this class from 2000 rubles. This is the average cost of good appliances.
The IEK difavtomat is somewhat cheaper. Equipment with similar characteristics will cost the buyer about 800-900 rubles. However, the quality of European brands is considered an order of magnitude higher.
It should be noted that in the network difautomats are extremely rarely duplicated by other similar protective devices. Therefore, the entire responsibility for the safe operation of the electrical network lies with the RCBO. To exclude the possibility of an accident, damage to property, the choice of the presented device must be approached responsibly.
Features of choice
To ensure the normal functioning of the power grid, it is necessary to select a difavtomat that will fully comply with the existing operating conditions. First you need to calculate the number of amperes of the device.
It is necessary to write out the power of all consumers of the network. They are added, and the result is divided by the voltage indicator of the network. For example, if devices are connected to the line that consume a total of 7 kW, the calculation will be as follows: 7,000 W: 220 V=31.8 A.
Next, choose the automaton closest to the obtained value. In the example shown, this will be a 32 A RCBO. The ampere rating of the unit should be slightly higher than that obtained atcalculation result. This is necessary to ensure full protection.
Specification symbols
Automatic residual current circuit breakers differ from RCDs in marking features. It is applied to the body. When purchasing a device, please take into account the designations indicated by the device manufacturer. The machine must indicate the current strength, voltage, as well as the indicator of the maximum current circuit to turn off the network. Also, all the characteristics of the device are indicated in its passport and quality certificate.
On the device indicates its type (selective or non-selective), the number of phases, as well as the size of the device (required to determine the type of installation). Marking for foreign and domestic devices may differ.
The device indicates the temperature range in which the equipment operates, the type of RCD. Almost all devices on sale are designed for operation in a dry, heated room.
Also, the device may have a "test" button. Pressing it checks the functionality of the machine. An artificial leakage of electricity is created. At the same time, it turns out to evaluate the reliability of the system, the correct installation.
Connection
Residual current circuit breakers require proper connection to the mains. Having chosen the device corresponding to the operating conditions, it is necessary to carefully study the manufacturer's instructions. The connection is made to the network that the machine should protect. Otherwise, his work will be incorrect.
Installation of popular appliancestoday brands are produced according to the same pattern. Installation is carried out above the wiring line. Most often, this process involves mounting the unit on a DIN rail.
Conductors must be connected in series. Cables of different circuits must not be connected. This requirement must be carefully monitored. Otherwise, the selective device will not perform the functions assigned to it in full. Metal leads must be grounded.
After installation, it is necessary to check. To do this, the “test” button is pressed, an artificial leak is created. If the unit works, then the installation was successful.
Having considered what the differential current circuit breakers are, as well as their features, you can correctly select and independently install the presented equipment into the network.
