Home electrics is a rather complex and diverse topic, and it is desirable for every homeowner to know the basic details, since not only money costs depend on this, but also the safety of your home. In this article we will try to find out which is better - difavtomat or RCD.
Introduction to the topic, or what is a difavtomat?
To deal with this issue, first let's try to define the basic concepts. So, difavtomat.
A device called a differential automaton successfully combines the functions of both an RCD and a conventional circuit breaker. This machine protects a person in case of touching the bare areas of the conductive part of the wire or those parts of electrical networks that are energized due to damage to the wiring or other similar factors. Today, there are a huge number of such devices that are designed for both different operating currents and different leakage currents.
Its main distinguishing featureis that it consists of two well-separated functional parts: a circuit breaker (two or four poles) and an electric shock protection module. The difavtomat should be mounted exclusively on a DIN rail, and this design takes up much less space than a combination of an RCD and a circuit breaker.
Given the response time, which is only 0.04 sec, differential automata provide the most adequate protection against electric shock to a person in almost any operating conditions. It is also important that the differential automaton qualitatively protects the devices in the network from overloads, which inevitably occur during various kinds of emergency. And further. Its design ensures the fastest possible power off in conditions where voltage surges over 250 V are observed in any part of the network.
Given the unenviable characteristics of domestic electrical networks, as well as the degree of their deterioration, the latter characteristic is especially important.
Main advantages of difavtomat
• Very fast response speed.
• Protection of equipment against power surges and operating overloads.
• Capable of operating in conditions from -25 to +50 degrees Celsius. • Huge wear threshold.
What is an RCD?
One cannot ignore the second “opponent” in the dispute on the topic “difamat or RCD”. What is an RCD?
This abbreviation stands for "safety deviceshutdowns." Operation is carried out when the presence of leakage currents is detected. Simply put, how much current came to the device through one wire, the same amount should go through another section of the wiring. If the current starts to go to the ground or through the ground wire, the protection immediately works, immediately disconnecting the network from the power source.
Such a system must (!) be installed on socket groups, as well as on boilers, washing machines and electric cookers. Such devices do not protect (!) your equipment and wiring from system overloads or short circuits.
The last circumstance is very often not taken into account by unfortunate electricians, who, in order to reduce the cost of the circuit, often use just one RCD. In addition, there is also a selfish interest when it is passed off as a differential machine, the cost of which is higher.
Basic information about the RCD device
What is the very principle of the RCD? Its operation is based on the reaction of the current sensor to a change in the differential current in the conductors.
What is a current sensor? This is the most common transformer, but made like a toroidal core. The threshold is set using a magnetoelectric relay, which has an extremely high sensitivity.
It is important to note that all RCDs made according to this classical scheme are extremely reliable and simple devices with very high reliability and reliability.
Necessarywarn that today there are also electronic RCDs, which are based on a special electronic circuit. A relay or circuit acts on a mechanism that opens the electrical circuit if necessary. Here's what an RCD device includes.
What parts does the actuator consist of?
- From the direct contact group, set to the maximum current.
- Springs that open the circuit directly if something goes wrong.
If you want to check the device for operability yourself, it will be enough to click on the "Test" button. In this case, current is artificially applied to the secondary winding, and the relay is activated (should, anyway). So if necessary, you can easily and at no cost to check the he alth of all your equipment.
The principle of operation of the RCD
If we talk about normal operation, then the current (I1=I2) flows in the opposite-parallel direction, inducing magnetic currents in the secondary winding of the transformer (Ф1=Ф2). They have exactly the same value, due to which they mutually compensate each other. Since the current in the secondary winding is in fact zero in this case, the relay cannot operate.
RCD operation in case of leakage
When in contact with conductive parts, leakage current occurs. In this case, the current I1 is not equal to I2, and therefore a current appears in the secondary winding, the value of which is sufficient to operate the protective relay. It provokes a spring switch, occursRCD shutdown.
Differences between the two security systems
To continue our story further, we also have to find out what is the difference between an RCD and a difavtomat. It cannot be said that the differences are so cardinal, but they are still there.
It should be noted that the coverage of this issue is extremely important, since even some electricians are sometimes unable to distinguish these devices from each other. However, there is nothing to be surprised here: they are extremely similar even in photographs.
The main difference between a difavtomat and an RCD is that they are intended for several different purposes. We have already said this above, but we will repeat it again: RCDs cannot be used to protect equipment and wiring from overload or short circuit! Moreover, it is imperative to install a circuit breaker in front of the RCD, which will save the device itself from this kind of trouble. This is how the RCD differs from the difavtomat.
Be sure to consider this when buying or consulting with especially "thoughtful" electricians who will gladly save on your own equipment.
Difaavtomat is much better in this regard, because it combines both an RCD and a circuit breaker in one case. Accordingly, this kind of device not only protects a person from electric shock, but also saves your wiring and equipment from burning out in the event of a short circuit. Thus, the RCD and the difavtomat, the difference between which we have just revealed, are somewhat diversemechanisms.
Recall again that the differential machine can be used as a fuse in those homes where there is a constant danger of chronic overloads in the network.
This is a detailed difference between an RCD and a difavtomat. But how to make the right choice in the store? After all, we have already said that these devices are extremely similar to each other even in photographs.
Buy it right
First, pay attention to the direct name of the device itself. Today, almost all manufacturers have finally gone to meet consumers, deigning to indicate on the body of the device itself information about whether a difavtomat or RCD is in front of you. Therefore, we would not recommend buying such Chinese-made equipment. Nosy Asians either do not indicate anything at all, or they do it using only understandable designations.
Approximately the same category includes advice on carefully reading the marking, which should always be indicated on the same device case or on its packaging (less reliable option).
So, if you see only the value of the rated current on the case (16, for example), and there are no letters in front of this designation, then you are holding an RCD. Note that "16" in this case means "ampere". If there are letters B, C or D in front of the numbers, then you have a difavtomat in your hands. The letters indicate the typical characteristics of thermal and electromagnetic releases, but at the household level it is not necessary to pay special attention to them.
Besides, it doesn't hurt to look at the diagram as wellconnections. This method is somewhat more complicated, but it gives a 100% guarantee of differentiation. This information must also be displayed on the case. So, if the diagram only indicates the presence of a difavtomat with the designation "Test", then you have an RCD in front of you (do not confuse it!). Accordingly, if there is a “Test” and the windings of the releases are indicated, then you are holding a differential machine in your hands.
Finally, it makes some sense to pay attention to the overall dimensions as well. If we talk about old models of difavtomatov, then they are an order of magnitude wider than RCDs. In those days, they simply did not know how to produce sufficiently compact releases, and therefore cases of a larger internal volume were required. Attention! All modern differential automata just take up less space!
However, it is important to warn you that you should not pay any serious attention to the last point, since there are currently a huge number of completely identical devices in size.
Go to the main thing
So, difavtomat or RCD? What conclusion can be drawn from the foregoing? What is better to choose, which is more reliable and suitable for operation in domestic realities? To answer this question, we will compare devices on six indicators at once. After comparing all the pros and cons, we will try to come to a consensus.
Volume occupied by the device in the shield
Of course, in this aspect, only those people who havethere is very little space in the apartment, which does not allow marking a normal electrical panel in the hallway. However, given the general desire for compactness and beauty, there are most of them in our country. In addition, it is better to place everything in advance in the smallest possible volume, since subsequently the shield will not have to be expanded if it becomes necessary to install more powerful electrical equipment in the apartment.
So, at present, the RCD (including three-phase) takes up much more space in the shield than a differential machine. What is it connected with? The most attentive readers themselves could already find the answer to this question in the article.
We have already talked about the need to install circuit breakers in front of the RCD, so because of this, the entire structure in the shield begins to take up more space. If you mount a differential machine there, you can save some space. For example: in the standard case, RCDs with circuit breakers occupy three modules at once, while a differential circuit breaker will occupy only two.
Thus, in this "round" the difavtomat won, allowing to leave room for the expansion of the structure.
Easy installation
As in other cases, for many electricians, it is the speed and ease of mounting the entire structure that is important. If you are interested in installing an RCD, the phase is led to the switch, and a jumper is mounted from its output to the input of the disconnect device. Zero is also connected to the input. It should be noted that there are several connection schemes at once,which are studied by professional electricians. As a rule, they are not needed in everyday life.
How to mount a differential machine?
And what about the connection of the difavtomat? If we talk about a differential automaton, then the phase and zero immediately cling to the input terminals of the device, so that in the general circuit it turns out much less jumpers and transitions. Accordingly, the internal structure of the shields is also greatly simplified.
Thus, connecting a difautomat is much easier and faster, so in this case, we confidently award the victory to him.
Operating Benefits
Theoretically, we can assume that one day the RCD worked on the line of sockets in the bathroom. You can immediately assume that somewhere on the line there was a current leakage. Of course, the troubleshooting algorithm is somewhat more complicated, but the main conclusions can be drawn immediately.
If the circuit breaker tripped, then here the reason is quite obvious: overload or short circuit. You just have to find out the cause and eliminate it. Given that the reason for disabling the machine is more or less clear, it will not be so difficult to do this.
And now let's consider all the same, but in relation to the differential automaton. When you turn it off, the reason is not immediately clear, so you will have to check all known causes. Accordingly, it will take much more time. This is how the RCD differs from the difavtomat in this regard.
So at this stage we would prefer RCDs.
Question of cost
Because todaythere are a huge number of the most diverse manufacturers on the market, consider the cost of EKF products, which are quite popular among professional electricians. So, a standard EKF difavtomat for 16 A costs about 600 rubles, an RCD for the same amperage costs the same 600 rubles, and a disconnect switch is sold at a cost of about 40 rubles. When purchasing all the same on specialized sites, you can even count on automatic cut-offs, which in such cases are sold almost by weight.
Before connecting the difavtomat, you should make sure that there are no frequent and sudden voltage drops. Why are we talking about this? This will become clear after considering the specifics of replacing this equipment.
Given the fluctuations in cost depending on the supplier, it is difficult to talk about the advantages of one or another option.
Lifetime and replacement cost
As one might suppose, the characteristics of this criterion follow automatically from the previous one. Everyone knows that any electrical equipment has a certain service life, after which it becomes unsafe to operate it. Let's assume that for one reason or another, the RCD or the circuit breaker failed. What to do next? Change the failed part, after which the system will continue to work in the same mode.
But with the difavtomat the situation is not so clear. Suppose that the winding of any of the releases failed, while the built-in RCD showed its full performance during testing. Alas, but this is notmatters, since in any case you will have to replace the entire difavtomat, the price of which makes this event extremely unprofitable. It is much easier to replace a penny machine, which breaks down most often.
Thus, in this round, the victory is again for the RCD.
Reliable operation
Among experts, it is widely believed that devices that combine several functions at once are less reliable than machines that are designed for only one thing. So RCD or difavtomat? What to choose for the highest reliability?
You can argue about this for a long time, but practice has clearly shown that in fact the percentage of failures is almost the same. It is possible that this parameter depends solely on the manufacturer. So in this case it is extremely difficult to draw a conclusion about the unambiguous advantage of a particular device.
One can only say that the RCD, the connection diagram of which we have discussed above, implies greater reliability in the conditions of domestic voltage surges. Naturally, if you do not forget to connect a cut-off switch in front of it, as we have repeatedly mentioned above.
Thus, in most cases, RCD will still be the best choice. However, it all depends on the characteristics of your network, as well as on the size of the electrical panel.
