What does the rated current of the ouzo affect? Uzo, purpose, standards, selection, installation. Selection of RCD by rated current
According to standards and regulations, the production and testing of RCDs have a whole list of parameters and characteristics. It is not realistic to know them all, and there is no need to. It is unlikely that you will go shopping with a reference book and will check the RCD brand with tables, and it is not so easy to find such tables.
According to the regulations, RCD manufacturers are required to mark on the body the basic parameters of the RCD that are important for their correct installation. Let's look at the parameters of the RCD printed on its body, using the example of the IBK VD1-63 RCD.
The main parameters of the RCD printed on its body
I would like to note right away that depending on the manufacturer and country of manufacture, the number of parameters may be less.
1. Designations of terminals for connecting the device to the supply circuit. 2. Designations of terminals for connecting the load to the device.3. Device manufacturer. In an abbreviated version, the author's logo. 4. RCD model. Device model according to the manufacturer’s product range. Most often in an abbreviated version. 5. Rated current. The value of the current that the RCD can pass in normal “closed” mode. 6. Rated voltage: The voltage value for which the device is designed. 7. Rated current frequency: Current frequency value for which the RCD is designed. For one RCD there can be several current frequency values. 8. Differential operating current. The value of the differential current at which the RCD trips (opens). This value can be called the non-triggering current, that is, up to this value the RCD will operate in the “closed” mode. 9. Letter type of RCD, according to the type of differential operating current. Accepted letters: A, AC, B, S, G.
Let's stop here.
There are two types of RCDs depending on the power supply of the device. Electromechanical RCD does not require power supply to the input terminals; such an RCD is triggered using the power of the differential current.
Electronic RCDs, do not work without power supply to the input terminals. Their circuit contains a current amplifier that will not work without a third-party source.
13. The magnitude of the short-circuit current (short circuit). Let me remind you that an RCD without overcurrent protection does not “see” a short circuit and does not turn off the circuit when short circuit overcurrents appear. But with overcurrents, a large amount of thermal energy is released, and so, this value of the short-circuit current indicated on the device body shows what overcurrent value the RCD will withstand. 14. There are two badges left: Rosstandart and the fire resistance standard. The symbols are formal and mean that the RCD has passed all the necessary tests according to GOST.Electromechanical RCDs are more stable and reliable.
Preferred and standard values of residual current devices
According to standards, there are such concepts as Preferred and standard RCD values. We can say that these are the values of the most used RCDs.
- Preferred voltage ratings are 240 Volts and 120 Volts;
- Standard rated current values are 6, 10, 13, 16 10, 20, 32 Amperes;
- Standard values of the rated disconnecting differential current are selected from the following range: 0.006; 0.01; 0.03 Amp.
- The preferred nominal frequency values are 50 and 60 Hz.
- The standard value of the rated conditional short-circuit current is 1500 Amperes (import up to 10,000 A).
Sometimes manufacturers transfer some of the markings to the side walls of the case.
RCD – residual current device. Currently, RCD is used almost everywhere, and in new buildings it is mandatory.
We install RCDs in apartment panels and in electrical panels of private houses. And this, of course, is correct, only RCD saves a person from electric shock. The RCD also protects our apartment or private house from fires that occur due to faults in the electrical wiring (poor contact, destruction of wire insulation). In my opinion, to such a question as how to install an RCD or not, there can only be one answer - The RCD must be installed in the electrical panel.
According to GOST 51326.1-99“Automatic circuit breakers controlled by differential current for household and similar purposes without built-in overcurrent protection” automatic circuit breakers controlled by differential current. current (RCD) have the abbreviation VDT(residual current switches). You can find this name for RCD in technical literature, in the names of products in online stores. In France, RCDs are designated ID (Schneider), in England - RCCD's.
Operating principle of RCD
Operating principle of RCD based on comparison of currents, which flow through the RCD, i.e. in your own words - what amount of current passed through the RCD
to consumers, the same amount of current should exit back from the RCD through the neutral conductor. In the picture, I 1 is the current in the RCD to the power receiver, I 2 is the current in the RCD from the power receiver. I 1 = I 2 - this condition is met when the electrical wiring is done well or there is no interference in the operation of the electrical wiring.
Suppose a person touches some conductor (phase or zero), in this case the person “takes” part of the current I∆n onto himself, and there will no longer be equality between I 1 and I 2, because I 1 > I 2 - I∆n. The RCD will sense this and turn off, thereby saving a person from probable death due to electric shock. The RCD must operate within 25-40 ms so that the current that will flow through the body does not increase to a fatal level.
RCD by number of phases
RCD there are single-phase and three-phase. Here I think everything is clear, if the network is single-phase, then the RCD is single-phase - it occupies 2 modules (phase and zero). If the network is three-phase, then the RCD is three-phase - it occupies 4 modules (three phases and zero).
I would like to note that in private homes, where three phases with a power of 15 kW have recently been connected, it is not correct to protect people from injury electric shock or fire safety, install a common three-phase RCD, because if there is a current leak in one of the phases, a three-phase RCD will turn off all three phases. A three-phase RCD is installed on individual three-phase consumers, hobs (electric stoves), boilers in private homes.
Selection of RCD by rated current
Well-known manufacturers such as ABB and Schneider Electric produce modular RCDs, which are installed on a DIN rail, with rated currents of 16, 25, 40, 63 A. The rated current of the RCD shows the amount of current that the RCD can pass for as long as desired. Based on this range of rated currents, you should choose an RCD for an electrical panel in an apartment or private house.
It's important to know that The RCD does not have overcurrent protection(short circuit currents, overload) and therefore it should always be protected, the rated current of which is less than or equal to the rated current of the RCD - this is according to the rules. But I'm selecting an RCD differently, strictly one step above the automatic .
I’ll explain why, the machine, as is known, passes current up to 1.13 of I nom. indefinitely long, and in the range from 1.13-1.45 I nom. for 1 hour. Suppose we chose a 25A machine and an RCD also 25A. As a result, for a whole hour, the RCD, which is designed for 25A, will pass a current of 25 * 1.45 = 36A, I don’t know what will happen to the RCD in this case, but I think that the 25A RCD is highly likely to burn out.
The rated current of the RCD is indicated on its front part.
There are RCDs with rated currents of both 32A and 50A, but these are Chinese RCDs, serious brands such as ABB, Schneider Electric or Legrand do not produce RCDs of this rating.
Examples of how to choose the right RCD based on rated current:
At the same time, remember that if “from above” the RCD is already protected by an automatic machine, the nominal value of which is less than the nominal value of the RCD, then after this RCD you can connect machines with a sum of ratings of at least 1000 A.
Rated breaking current of RCD
Rated breaking current of RCD I∆n(setpoint) is the current at which the RCD is triggered(turns off). The RCD settings are 10 mA, 30 mA, 100 mA, 300 mA, 500 mA. It should be noted that non-release current when a person can no longer unclench his hands and throw away the wire on his own, amounts to 30 mA and above. Therefore, to protect a person from electric shock, an RCD with a breaking current of 10 mA or 30 mA is chosen.
Rated breaking current of the RCD I∆n or leakage current is also indicated on the front panel of the RCD.
RCD 10 mA is used to protect electrical receivers in damp rooms or wet consumers, i.e. washing machines and dishwashers, sockets that are located inside the bath or toilet, light in the bathroom, heated floors in the bathroom or toilet, light or sockets on balconies and loggias.
SP31-110-2003 p.A.4.15 For plumbing cabins, bathtubs and showers, it is recommended to install an RCD with a rated differential trip current up to 10 mA, if a separate line is allocated for them, in other cases, for example, when using one line for a bathroom, kitchen and corridor, an RCD with a rated differential current of up to 30 mA should be used.
Those. The RCD with a setting of 10 mA is installed on a separate cable, to which only the washing machine is connected. But if other consumers are still powered from the cable line, for example, sockets in the corridor or kitchen, then in this case an RCD with a response current (set) of 30 mA is installed.
ABB produces RCDs with a leakage current of 10 mA only at 16A. Schneider Electric and Hager have RCDs for 25/10 mA and 16/10 mA in their product line.
RCD 30 mA installed on standard lines, i.e. regular household sockets, lights in rooms, etc.
PUE clause 7.1.79. In group networks supplying plug sockets, an RCD with a rated operating current should be used no more than 30 mA. It is allowed to connect several RCDs to one group lines through separate circuit breakers(circuit breakers).
RCD 100, 300, 500 mA called fire protection, such RCDs will not save you from a fatal electric shock, but will protect your apartment or private house from a fire due to faulty electrical wiring. Such 100-500 mA RCDs are installed in input panels, i.e. at the beginning of the line.
In the USA they use RCDs with a rated breaking current of 6 mA, in Europe up to 30 mA.
It should be noted that The RCD is switched off within the setting range of 50-100%, i.e. if we have a 30 mA RCD, then it should turn off within 15-30 mA.
There are designers who promote double diffs. protection of “wet” consumers. This is when, for example, a washing machine is connected to a 16/10 mA RCD, which in turn is connected to a 40/30 mA group RCD.
In the end, what do we get? At the slightest “sneeze” from the washing machine, we turn off the entire group of machines (kitchen light, boiler and room light), because in most cases it is not known which RCD 25/30 mA or 16/10 mA will work, or whether both will work.
According to the set of rules for the design of electrical installations of residential and public buildings:
SP31-110-2003 p.A.4.2
But in fairness, it should be noted that if the electrical wiring is installed efficiently, then the RCDs do not operate for years. Therefore, in this case, the final word belongs to the customer.
Types of RCD according to the operating principle
Based on the operating principle, RCDs are divided into electronic and electromechanical. Electronic RCDs are an order of magnitude cheaper than electromechanical RCDs. This is explained by its lower reliability and low cost of production. An electronic RCD is “powered” from the network, and the operation of an electronic RCD depends on the parameters and quality of this same electrical network.
Let me give you an example: our zero in the floor panel has burned out, and accordingly the power to the electronic RCD will be lost and it will not work. And if at this time a phase short circuit occurs on the body of the device, and a person touches it, then the electronic RCD will not work, because it simply simply does not work, there is no power supply to the electronics due to a zero break. Or if, simply put, electronics are electronics, and Chinese electronics are doubly “electronics” that can fail at any moment. Therefore, an electromechanical RCD, which does not depend on the state of the network, is much more reliable than an electronic RCD.
The principle of operation is based on a comparison of the incoming and outgoing current of the RCD of a conventional differential current transformer, and if the current is not equal to and greater than the setting (rated breaking current of the RCD in mA), as already indicated above, then the RCD is turned off.
From these diagrams you can determine whether the RCD is electronic or electromechanical; the diagrams are applied to the RCD housings.
Well-known manufacturers such as ABB, Schneider Electric, Hager or Legrand do not produce electronic RCDs, only electromechanical RCDs. I install electromechanical RCDs in my electrical panels.
To compare electronic and electromechanical RCDs, I offer a photo with their “internals”. I would post an electronic RCD from a well-known brand, not a Chinese one, but, as I wrote above, ABB, Schneider Electric, Legrand and other serious manufacturers do not produce electronic RCDs.
RCD types AC, A, B
Depending on the type, the RCD is required to disconnect from different types of current leaks, there are RCDs that disconnect only alternating current, there are RCDs that switch off alternating and pulsating current:
Reacts to instantaneous alternating differential leakage current, i.e. these are ordinary consumers: lighting, heated floors, refrigerators, convectors, etc. The type of RCD AC is indicated on the panel, these are either the letters AC or special character(pictogram) or both together.
Reacts to both alternating and pulsating leakage current, which can slowly increase or occur suddenly. These are devices that use rectifiers and switching power supplies: computers, washing machines, televisions, dishwashers, microwave ovens, i.e. where everything is controlled by electronics. Some instructions for modern electrical appliances specifically indicate that it is necessary to install a type A RCD. The pictogram for a type A RCD looks like this
RCD type A is more expensive than RCD type AC, because “covers” a larger protection zone. But it should be noted that the level of protection with an AC type RCD is higher than if there were no RCD at all.
PUE 7.1.78. In buildings, RCDs of type “A” can be used, which respond to both alternating and pulsating fault currents, or “AC”, which react only to alternating leakage currents. The source of pulsating current are, for example, washing machines with speed controllers, adjustable light sources, TVs, VCRs, personal computers and etc.
Readers often have a question: “Which RCD should I put on a refrigerator, washing machine, dishwasher, hob, etc.?” The most correct answer can be found in the instructions for household appliances.
But, for example, in Europe it is allowed to install only type A RCDs. AC type RCDs are prohibited.
RCD type B- a rarity in Russia, they are used in industry, where, in addition to other types of leaks, there are rectified current leaks; type B RCDs are not used in everyday life.
Trip delay (selectivity) RCD
Based on the response time, RCDs are divided into 3 types:
RCD without time delay, are used to protect people from electric shock and fire due to electrical wiring faults. An RCD without a time delay is installed on the lines of electrical receivers. And they are the first stage of protection.
RCD type S (selective), also called fire protection. This type S RCD operates with a delay (0.2-0.5 seconds), so it does not protect a person, but only protects against fires. Fire protection RCD installed at the beginning of the line after the opening machine and protects the input cable and the automation connection in the panel, and is also the second stage of the differential. protecting the entire house from fire.
You can determine that this RCD is selective by the letter “S” on the panel, which indicates that the RCD is selective with a time delay for shutdown.
Examples a single-phase selective fire protection RCD from ABB with a leakage current of 100 mA and a three-phase fire protection RCD at 300 mA from Schneider Electric.
RCD type S is selected with a rated leakage current of 100-300 mA. A fire RCD with a setting of 100-300 mA is the second stage of protection, and according to the rules, if several RCDs are installed on the same line in a circuit, then each subsequent stage must have a longer response time and current setting.
SP31-110-2003 p.A.4.2 When installing an RCD, selectivity requirements must be consistently met. With two- and multi-stage circuits, the RCD located closer to the power source must have tripping current settings and response time at least three times greater than that of the RCD located closer to the consumer.
If there were no time delay, and we have two RCDs on the line, one for 30 mA, the other for 100 mA, then in case of current leaks If both RCDs would trip and a 100 mA RCD would de-energize the entire house. Therefore, in order not to run out into the street in shorts in the cold and turn on the fire protection RCD in the street panel, fire protection RCD is selected with a setting sufficient to prevent fire.
RCD type G, the same as type S, only with a shorter time delay of 0.06-0.08 seconds. RCDs are rare, and I had to wait 2-3 months for their “arrival”, which is very inconvenient for me, because... electrical panels freeze for a long time.
RCD connection diagram
Power (electricity) can be supplied to both the lower and upper contacts of the RCD - this statement applies to all leading manufacturers of electromechanical RCDs.
Example from the instructions for the ABB F200 RCD
I share RCD connection diagrams for 2 types:
Connection diagram for a three-phase electric motor via an RCD
People often ask in the comments about connecting a three-phase motor (pump) through an RCD; the question arises due to the lack of a neutral in three-phase electric motors.
Actually, there is nothing complicated about this; for the correct operation of a three-phase RCD, we connect the neutral conductor to the neutral terminal of the RCD on the power side, and on the motor side it remains empty.
The RCD should be checked at least once a month. This is done quite simply, just click to the "TEST" button, which is available on any RCD.
The RCD must turn off; this should be done when the load is removed, when TVs, computers, washing machines, etc. are turned off, so as not to “tug” sensitive equipment again.”
I like ABB RCDs, which, like the ABB S200 series switches, have an indication of the on (red) or off (green) position.
Just like ABB S200 switches, there are two contacts on each pole at the top and bottom.
Thank you for your attention.
RCD(Residual Disconnection Device) is a switching device designed to protect an electrical circuit from leakage currents, that is, currents flowing along undesirable, under normal operating conditions, conductive paths, which in turn provides protection from fires (electrical wiring fires) and from electric shock to humans. electric shock
The definition of “switching” means that this device can turn on and off electrical circuits, in other words, switch them.
RCD also has other names, for example: differential switch, differential current switch, (abbreviated as differential current switch), etc.
Design and operating principle of RCD
And so, for clarity, let’s imagine the simplest scheme connections via RCD light bulbs:
The diagram shows that during normal operation of the RCD, when its moving contacts are closed, a current I 1 of value, for example, 5 Amperes from the phase wire passes through the magnetic circuit of the RCD, then through the light bulb, and returns to the network via the neutral conductor, also through the magnetic circuit of the RCD, and the value of the current I 2 is equal to the value of the current I 1 and is 5 Amperes.
In such a situation, part of the electrical circuit current coming from the phase wire will not return to the network, but passing through the human body will go into the ground, therefore the current I 2 which will return to the network through the magnetic circuit of the RCD along the neutral wire will be less current I 1 entering the network, respectively, the value of the magnetic flux F 1 will become greater than the value of the magnetic flux F 2, as a result of which the total magnetic flux in the RCD magnetic circuit will no longer be equal to zero.
For example, current I 1 = 6A, current I 2 = 5.5A, i.e. 0.5 Ampere flows through the human body into the ground (i.e. 0.5 Ampere is the leakage current), then the magnetic flux Ф 1 will be equal to 6 conventional units, and the magnetic flux Ф 2 will be 5.5 conventional units, then the total magnetic flux will be equal to:
F sums = F 1 + F 2 =6+(-5.5)=0.5 arb. units
The resulting total magnetic flux induces an electric current in the secondary winding, which, passing through the magnetoelectric relay, puts it into operation, and it, in turn, opens the moving contacts, turning off the electrical circuit.
The functionality of the RCD is checked by pressing the “TEST” button. Pressing this button artificially creates a current leak in the RCD, which should lead to the RCD turning off.
RCD connection diagram.
IMPORTANT! Since the RCD does not have overcurrent protection, any circuit for its connection must also include an installation to protect the RCD from overload and short circuit currents.
RCD connection carried out according to one of the following schemes, depending on the type of network:
Connecting an RCD without grounding:
This scheme is used, as a rule, in buildings with old electrical wiring (two-wire), in which there is no ground wire.
Connecting an RCD with grounding:
N-C-S(when the neutral conductor is divided into zero working and zero protective):
Connection diagram of the RCD in the electrical network(when the neutral working and neutral protective conductors are separated):
IMPORTANT! In the coverage area of the RCD, you cannot combine the neutral protective (grounding wire) and the neutral working conductors! In other words, it is impossible in the circuit, after the installed RCD, to connect the working zero (blue wire in the diagram) and the ground wire (green wire in the diagram).
Errors in connection diagrams due to which the RCD trips.
As mentioned above, the RCD is triggered by leakage currents, i.e. if the RCD has tripped, this means that a person has come under voltage or for some reason the insulation of the electrical wiring or electrical equipment has been damaged.
But what if the RCD trips spontaneously and there is no damage anywhere, and the connected electrical equipment is working properly? Perhaps the whole point is one of the following errors in the network diagram of the protected RCD.
One of the most common mistakes is combining the neutral protective and neutral working conductors in the coverage area of the RCD:
In this case, the amount of current leaving the network through the RCD along the phase wire will be greater than the amount of current returning to the network through the neutral conductor because part of the current will flow past the RCD along the grounding conductor, which will cause the RCD to trip.
Also, there are often cases of using a grounding conductor or a third-party conductive grounded part (for example, building fittings, a heating system, a water pipe) as a neutral working conductor. This connection usually occurs when the neutral working conductor is damaged:
Both of these cases lead to the RCD tripping, because The current leaving the network through the phase wire does not return through the RCD back to the network.
How to choose an RCD? Types and characteristics of RCD.
To choose the right RCD and eliminate the possibility of error, use ours.
The RCD is selected according to its main characteristics. These include: 
- Rated current— the maximum current at which the RCD can operate for a long time without losing its functionality;
- Differential current— the minimum leakage current at which the RCD will disconnect the electrical circuit;
- Rated voltage- voltage at which the RCD is able to operate for a long time without losing its functionality
- Current type— constant (denoted by “-“) or variable (denoted by “~”);
- Conditional short circuit current- current that the RCD can withstand for a short time until the protective equipment (fuse or circuit breaker) trips.
RCD selection is based on the following criteria:
— By rated voltage and network type: The rated voltage of the RCD must be greater than or equal to the rated voltage of the circuit it protects:
Unom. RCD⩾ Unom. networks
At single-phase network required two-pole RCD, at three-phase network — four-pole.
— By rated current: The rated current of the RCD must be greater than or equal to the rated current of the circuit it protects, i.e. the current for which this electrical network is designed:
Inom. RCD⩾ Icalc. networks
The network current can be calculated using ours, or it can be determined independently using the formula
Inetworks= Pnetworks*K p, Ampere
Where: Pnetworks— network power, in kilowatts; K p— conversion factor equal to: 1,52 -for 380 Volt network or 4,55 - for a 220 Volt network:
After calculating the mains current, we accept the nearest higher standard value of the rated current of the RCD: 4A, 5A, 6A, 8A, 10A, 13A, 16A, 20A, 25A, 32A, 40A, 50A, 63A, etc., and it is recommended to accept the RCD with rated current one step higher than calculated, for example, if as a result of the calculation the network current was 22 Amperes, then the nearest standard value of the rated current of the RCD will be 25 Amperes, however, you should select an RCD with a rated current one step higher, i.e. 32 Amps.
The power of the network is determined by summing the powers of all electrical receivers connected to the network protected by the calculated RCD:
P network =(P 1 + P 2 ...+ P n)*K s, kW
Where: P1, P2, Pn— power of individual electrical receivers in kilowatts; K s— demand coefficient (K c = from 0.65 to 0.8) if only 1 power receiver or a group of power receivers that are connected to the network at the same time is connected to the network K c = 1.
As the network power, you can also take the maximum power allowed for use, for example, from technical conditions, a project or a power supply contract, if any.
Because The RCD does not have protection against short circuit currents; it must be protected by a fuse or circuit breaker installed in the circuit. The rated current of the RCD can also be selected based on the rated current of the fuse or circuit breaker, and it is recommended that the rated current of the RCD be one step higher than the rated current of the protection device.
For example: You determined the calculated network current which was 22A (Ampere), from the line of standard ratings: 4A, 5A, 6A, 8A, 10A, 13A, 16A, 25A, 32A, 40A, 50A, 63A, you selected the closest value of the rated current of the automatic switch - 25A, then it is recommended that you take an RCD with a rated current of 32A.
— By differential current:
Differential current is one of the main characteristics of the RCD, which shows at what value of leakage current the RCD will turn off the circuit.
In accordance with paragraph 7.1.83. PUE: The total leakage current of the network, taking into account the connected stationary and portable electrical receivers in normal operation, should not exceed 1/3 of the rated current of the RCD. In the absence of data, the leakage current of electrical receivers should be taken at the rate of 0.4 mA per 1 A of load current, and the network leakage current at the rate of 10 μA per 1 m of phase conductor length. Those. The differential network current can be calculated using the following formula:
Δ I network =((0.4*I network)+(0.01*L wire))*3, milliamperes
Where: Inetworks— network current (calculated using the formula above), in Amperes; Lwires— total length of the protected electrical network wiring in meters.
Having calculated ΔI network we accept the nearest higher standard value of the residual current of the RCD Δ I RCD:
Δ I RCD ⩾ ΔI network
The standard values of the residual current of the RCD are: 6, 10, 30, 100, 300, 500mA
Differential currents: 100, 300 and 500 mA are used for protection against fires, and currents: 6, 10, 30 mA are used to protect against electric shock. In this case, currents of 6 and 10 mA are used, as a rule, to protect individual consumers and, and a differential current of 30 mA is suitable for general protection of the electrical network.
If an RCD is needed to protect against electric shock, and according to the calculation, the leakage current is more than 30 mA, it is necessary to provide for the installation of several RCDs on different groups of lines, for example, one RCD to protect sockets in rooms, and a second to protect sockets in the kitchen, thereby reducing the most power passing through each RCD and, as a result, reducing the network leakage current, i.e. in this case, the calculation will need to be made for two or more RCDs that will be installed on different lines.
— By type of RCD:
There are two types of RCDs: electromechanical And electronic. We discussed the principle of operation of an electromechanical RCD above; its main working element is a differential transformer (magnetic core with a winding) that compares the magnitude of the current going into the network and the current returning from the network, and in an electronic device this function is performed by an electronic board that requires voltage to operate.
Let’s imagine a situation: for some reason the zero “disappeared” (for example, the neutral conductor burned out), and if an electronic RCD is installed in the network, its electronic board will be de-energized and if a person touches the phase wire and comes under voltage, this RCD will not work, but the electromechanical The RCD will remain operational even in the absence of voltage and will disconnect the electrical circuit, therefore it is preferable to use 10
A large amount of equipment and household appliances installed in apartments and private houses significantly increases the likelihood of electric shock, wiring fires, and equipment failure due to network faults. Protective devices - circuit breakers and residual current devices, abbreviated as RCDs - help to avoid unpleasant consequences. If the wiring or the household appliance itself malfunctions, a leakage current occurs, also known as . Direct contacts with it lead to electrical injuries, so in all cases it is required reliable protection of people.
In order for the protection to be as effective as possible, it is necessary to correctly select the characteristics of the RCD. Selecting parameters protective device depends on its intended purpose and the characteristics of the home electrical network.
RCD response time
Based on the response time, RCDs are divided into two main types - S and G. They are used in switchboards of increased complexity to ensure selectivity in protected areas. For comparison, it should be noted that conventional protective devices operate when a current leak occurs in approximately 0.02-0.03 seconds. This option is ideal for those lines where there is only one RCD installed for the entire network.
Many schemes involve installing an input protective device and another one for each outgoing line. In the event of a malfunction in such a circuit, all devices should not operate simultaneously. To avoid this, there is precisely type S with a response time delay of 0.15-0.5 seconds and type G with a delay of 0.06-0.08 seconds. As a result of such delays, the general input protection continues to remain in the operating position, and the entire apartment is not de-energized.
The tripping time is considered to be the interval between the sudden appearance of the differential tripping current and the moment when the arc is extinguished at each pole of the device. There is another concept called non-shutdown time limit. It is typical for RCD type S and is the maximum period of time from the onset of the breaking current in the main circuit of the device to the moment the breaking contacts begin to move. This indicator represents a time delay that ensures the selective action of RCDs operating in multi-level protection systems.
Modern electromechanical protective devices High Quality have a speed of 20-30 milliseconds. Such RCDs belong to the category of fast switches that operate before equipment protecting against overcurrents. As a result of operation, not only load currents are switched off, but also overcurrents.
RCD current
An equally important characteristic of residual current devices is their rated current. At its core, this parameter is the amount of current that an RCD can pass for an unlimited time. The standard rated currents for which modern RCDs are produced are 16, 25, 32, 40 and 63 amperes. This line allows you to choose the most suitable option for protecting your apartment or private home.
It should be remembered that the residual current device does not protect against overcurrents resulting from overloads and short circuits. Therefore, this device is commonly used. In this case, the rated current of the machine must be less than or equal to the rated current of the RCD.
There is another current characteristic called the rated breaking current of the protective device. In fact, it is the setting, that is, the current at which the RCD is triggered and switched off. The settings also have their own range - 10, 30, 100, 300 and 500 mA.
When choosing a device, you need to remember about the so-called non-releasing current, which is 30 or more milliamps, at which it becomes impossible to independently unclench your hands and throw away the wire. Therefore, the breaking current protection intended to protect people is selected at 10 or 30 mA. This value is also included in the markings applied on the front side of the RCD.
Each device has its own purpose:
- 10 mA devices protect consumers located in rooms with high humidity, as well as devices and equipment operating in wet mode - dishwashers and washing machines. This also includes sockets installed in toilets and baths, on balconies and loggias. These RCDs are used subject to the allocation of separate lines to each consumer. If another load is connected to this line, a 30 mA protective device will be required.
- An RCD with a disconnecting current of 30 mA is installed on standard lines with ordinary consumers - sockets, lighting, etc.
- Protective devices for 100, 300 and 500 mA are classified as . They are not able to protect against electric shock, but these devices successfully prevent fire in an apartment or private house due to faulty wiring.
When installing RCDs in series, selectivity must be ensured. In multi-stage circuits, the protective device located closest to the power source must have a current and response time at least three times higher than that of the device installed in the immediate vicinity of the consumer.
RCD parameters
In addition to the characteristics already discussed, other parameters that are important when choosing a device in accordance with operating conditions are applied to the front part of the device as markings.
Among them, it is worth noting the rated voltage. In single-phase RCDs its value is 230 V, and in three-phase RCDs it is 400 V. Both parameters correspond to alternating voltage. This characteristic is very important, since electronic RCDs are highly sensitive to voltage surges. The main element of the device is an electronic board powered by mains voltage. In case of any deviations, the operation of the RCD will simply be disrupted.
Another characteristic is called the rated conditional short-circuit current. Despite the joint use of machines, there is always the possibility of overcurrents flowing through the RCD. This parameter means resistance to short circuit currents, that is, the ability to pass overcurrents through itself without loss of performance. It also has its own line - 3000, 4500, 6000 and 10000 A. The higher this indicator, the more reliable the device.
Other RCD parameters:
- Rated breaking and making capacity switched by the protective device itself.
- Rated differential breaking and making capacity, allowing differential short circuit currents to pass through without loss of performance.
- Rated non-tripping differential current, which under given operating conditions does not trigger the RCD.
In addition, a power connection diagram is applied to the front panel, indicating the corresponding terminals for the phase wires and the neutral conductor.
The increase in the number of household appliances increases the risk of electrical injury during their operation. Therefore, it is recommended to install protective systems in premises that prevent current leakage.
To ensure stable operation and safe use of devices, it is necessary to correctly select and install the RCD. Before purchasing, you should evaluate the operational features of the room, the type of electrical wiring and decide on the connection diagram of the protective device.
Do you doubt that you can cope with the task? We will tell you how to choose an RCD, what parameters are important to consider to ensure normal functioning equipment, and which manufacturers can be trusted.
It was invented to prevent accidental electric shock from contact with household and industrial electrical appliances.
It is based on a transformer with a toroidal core, which monitors the current strength at “phase” and “zero”. If its levels diverge, then the relay is activated and the power contacts are disconnected.
You can check the RCD by pressing the special “TEST” button. As a result, a current leak is simulated, and the device must disconnect the power contacts
Normally, any electrical device has a current leakage. But its level is so low that it is safe for the human body.
Therefore, RCDs are programmed to operate at a current value that can cause electrical injury to people or lead to equipment breakdown.
For example, when a child inserts a bare metal pin into an outlet, electricity will leak through the body, and the RCD will turn off the light in the apartment.
The speed of operation of the device is such that the body will not experience any negative sensations at all.
The RCD adapter is convenient because it allows you to quickly move between sockets. It is suitable for people who do not want to install stationary protective devices
Depending on the power of the connected equipment, the presence of intermediate protective devices and the length of the electrical wiring, RCDs with different limiting values of differential currents are used.
The most common protective devices in everyday life are those with threshold levels of 10 mA, 30 mA and 100 mA. These devices are sufficient to protect most residential and office premises.
It should be remembered that the classic RCD does not protect electrical wiring from short circuits and does not disconnect power contacts when the network is overloaded. Therefore, it is advisable to use these devices in combination with other electrical protection mechanisms, for example.
Classification of protective devices
Despite the simplicity of the internal structure, the choice of RCD models on the market is quite large. Each device has a certain set of technical parameters that cannot be adjusted during operation.
The manufacturer and size of the RCD do not affect the possibility of sharing within the same circuit. They can be mounted in any combination
To facilitate the selection of RCDs, options for classifying these devices should be considered.
- By response speed RCD mechanisms are divided into conventional and selective models. The former disconnect power contacts almost instantly, while the latter disconnect with a delay. Selective RCDs are used in multi-level systems where the sequence of operation is important.
- By type of relay RCDs are divided into electromechanical, which breaks the contact mechanically, and electronic, which prevents the flow of current using a semiconductor circuit.
- By type of current. RCD type AC is disconnected from alternating current leakage, type A – from alternating and direct current.
- By additional functions: without and with network overload protection. RCDs with a short circuit or high current trigger mechanism are usually called difavtomats.
- By design. There are RCDs that are attached to a DIN rail, to the wall, as well as devices in the form of a socket, a portable device, or an adapter.
- According to operating voltage: for 220V, 380V, combined.
- By energy dependence. There are RCD models that are capable and unable to disconnect the power load in the absence of operating voltage.
- By number of connected poles: two-pole and four-pole.
To choose the right RCD, it is not enough to know it specifications. In order for the device to effectively perform its protective function, when purchasing it, you need to take into account the length of the home electrical wiring, the power of the connected devices and some other parameters.
Rules for choosing protective devices
Before purchasing an RCD, you can visit electrician forums to seek advice on the reliability of a particular manufacturer.
However, it is necessary to select the maximum and threshold current, number of poles, mounting scheme and other technical parameters strictly individually, based on the characteristics of the room and electrical wiring.
Selecting a device by power
The residual current device does not control the power consumption of connected devices, but has limitations on the maximum current flow.
Conclusions and useful video on the topic
Selection of RCD with consideration of options, as well as explanations of the features of various connection schemes:
Rules for choosing an RCD, part 1:
Rules for choosing an RCD, part 2:
The choice of a suitable RCD, especially when installing two-level systems, is best left to professionals.
It’s easier to invite an experienced electrician into your home once and consult with him than to change an unsuitable product in a store. After all, the health and lives of loved ones who will use household electrical appliances are at stake.
Do you have anything to add or have questions about choosing a protective device? You can leave comments on the publication, participate in discussions and share your own experience in selecting an RCD for a house or apartment. The contact form is located in the lower block.
