If you are involved in the electrical installation in the apartment yourself, then sooner or later the time comes when the home master is faced with the need to assemble an introductory switchboard. And here the question arises, what kind of automation is better to install in order to protect the home power network as much as possible. Many do not understand how some devices differ from others. Today it’s worth shedding light on such complexities of choice. The article will discuss how to distinguish RCDs from a difavtomat, what functions these modular elements perform and what is better to choose to protect your loved ones from possible electric shock, and the power network from overloads and short circuits.
Purpose of protective automation: is there a need for installation
Such equipment, depending on the type, is able to provide security in various ways. For example, the difference between an RCD and a differential automaton is primarily in functionality. But in order to make it easier for a respected reader, what exactly are the differences between some elements from others, it is worth considering their characteristics in detail. Only after their complete analysis can it be possible to answer this question.
Residual current device: cook it works
The RCD is responsible for cutting off the power supply in the event of a current leakage in the electrical network, ensuring human safety. Such automation is able to protect the owner in case of breakdown of the phase wire onto the metal housing of the household appliance. It also solves security issues in the event of a rather frequent situation when the washing machine is installed in the bathroom - in this case, dampness causes mild discharges that are felt by the user in contact with the surface of the unit.
The residual current circuit breaker differs in functionality from the circuit breaker in that it only responds to current leaks and does not turn off during short circuits or overloads. For this reason, RCDs require additional protection, the role of which is AB.
The differences between residual current circuit breakers and circuit breakers are clear. It remains to understand how RCDs differ from differential automata. The difference can be understood if we consider the characteristics of the AVDT.
Difavtomats and their functions
Similar devices are universal. They combined the functions of residual current circuit breakers and circuit breakers. Of course, their cost is slightly higher, but sometimes there is simply no other way out than installing an AVDT. The fact is that the UZO / AV bundle occupies 3 modular places on the DIN rail in the distribution cabinet, while the difavtomat, which does not require additional protection, is only 2. Today, more miniature devices of this type have also appeared. Their dimensions are equal to the sizes of a single-pole machine, however, judging by the feedback from users, their service life is much shorter than that of full-fledged high-voltage circuit breakers.
It turns out that installing a difavtomat instead of an RCD is quite simple - these steps do not require the purchase of additional equipment. But if AVDT was originally installed, then acquiring a residual current device, you will have to spend money on AV, which will protect it from network congestion and short circuits.
RCD or differential automaton: visual differences
It is difficult for an uninitiated person to understand which device is in front of him. Externally, the RCD is practically no different from the AVDT. However, a knowledgeable home master will be quite easy to figure out. So how to distinguish an RCD from a difavtomat visually? The main thing here is to understand what the markings on the front panel mean.
With Russian-made products, everything is quite simple. They clearly spelled out which device a person holds in his hands. On the front panel can be printed "difavtomat" or "AVDT". If such markings are absent, it is necessary to pay attention to the alphanumeric designation.
The number and the subsequent letter "A" indicates that there is a protective shutdown device in front of the home master. For example, if 16A is affixed, then it is an RCD with a rated current load of 16 amperes. If the letter designation is before the numeric one (it can be the letters "B", "C" or "D"), then this is AVDT. For household networks, devices with the type of time-current characteristic “C” are used.
The labeling of RCDs and the differential machine can say a lot to a knowledgeable person. It indicates not only the type and rated current load strength. On the front panel, you can find the breaking capacity according to GOST, find out about the presence or absence of a thermal and electromagnetic release. Also, the marking will indicate the current limit class.
Protective device manufacturers popular among consumers
The number of companies offering similar products on the shelves of Russian stores is growing steadily. However, it is difficult for young brands to occupy their niche in the market of electrical appliances. Among consumers, brands are popular that have been manufacturing protective equipment for several years and have already proven themselves on the good side, due to the quality and reliability of the products. One of these brands can be called ABB. This company has long been known to the Russian buyer, people relate to its products with confidence. Due to this, RCDs and ABB difavtomats do not lie on the shelves.
Only the price policy of Italians, who manufacture products under this brand, is surprising. The cost of devices with almost identical characteristics can vary significantly. For comparison, we take 2 ABB difavtomats with a rated current load of 16 A and operation with a leakage of 30 mA. The price of devices is (by model):
- DS901 - 1600 rubles
- DS201 - 5100 rub.
But ultimately it is up to the homemaster to decide what to purchase.
Connection of protective automation in the control cabinet
The solution to this issue requires care and accuracy. It is not enough to know how to distinguish an RCD from a difavtomat. You must be able to properly connect both of these devices. Dear reader, I probably already understood that switching RCDs requires additional installation of an AV, so the circuit here is a little more complicated, but not so much that it was impossible to figure it out. It is necessary to make a reservation right away that in order to provide reliable protection for both devices, high-quality and properly functioning grounding is required. It is worth considering carefully the question of how to connect a difavtomat and an RCD.
Residual current device: how to install
The operation algorithm is as follows. After the metering device, an automatic switch is installed , and only after it is an RCD. When switching, it is necessary to pay attention to protective grounding - neither in the control cabinet, nor in apartment outlets, it should not contact the neutral wire. Otherwise, the RCD will periodically causeless operation, leaving the apartment without electricity.
Switching the residual current circuit breaker
Similar equipment is connected in the same way - from above is the input of phase and neutral conductors, from below is the voltage output to the apartment. The difference is that there is no need to install the machine in front of the automatic circuit breaker. It should be noted that if the phase and neutral conductors are incorrectly connected, causeless trips can also be observed, so you should carefully consider the markings of the contacts on the front panel. Information on the switching order of a device can be found in the circuit, which is located on the side.
Which is better - difavtomat or RCD?
This is a question that has been debated so far. It is the second most popular, among Internet users, after the main one - how to distinguish RCDs from difavtomat. Specialists and home craftsmen were divided into 2 camps. The former argue that the installation of the AVDT is simpler, the device takes up less space in the shield, which automatically makes it more in demand. The second, on the contrary, say that his problem lies in universality. Indeed, when installing the “UZO / AV” bundle, only one unit can be replaced if it fails, while in case of a breakdown of the circuit breaker, more expensive equipment will have to be purchased. In addition, there is a problem with determining the cause of the operation. It is unclear why the power supply turned off due to overload or leakage. If a bunch is established, such a question does not arise.
You can argue on this topic for a long time, but there are cases when there is no other way out than installing the AVDT due to the lack of free modular space on the DIN rail. In such cases, the question “what is better” fades into the background, giving way to practicality.
RCD and difavtomat: designation on the scheme
It is rather strange, but GOST does not give any explanations about how the residual current circuit breaker should look like on the circuit. Most often, each electrician notes a similar device in their own way. Over the years, a certain generally accepted image has developed (it can be seen below), which is used with certain deviations. Even if you pay attention to the devices themselves, the schematic images on the cases of devices of different brands are different.
GOST also does not provide for specific rules for designating a differential current circuit breaker . Such an omission causes a lot of problems in reading circuits as a result of misunderstanding - after all, every electrician believes that the image performed by him is the only correct one. Below you can see the generally accepted image. It is not a fact that in the circuit that fell into the hands of it it will be absolutely identical, but it will be possible to catch the general. This will make it a little easier to understand what exactly is installed in a particular distribution cabinet.
After familiarizing yourself with the generally accepted schematic images, it becomes clear how to distinguish RCDs from the difavtomat while reading projects.
To summarize today's conversation
When choosing protective devices for a home power network, you should be very careful. Before going to the store, you need to decide what equipment will be installed in the control cabinet. Being near the counter, you need to carefully study the markings on the device case, so as not to buy a residual current circuit breaker instead of an RCD, and vice versa. It makes sense to get acquainted with certificates and approvals for protective equipment, which must be mandatory with the seller. But in the end, no matter what the homemaster, RCD or AVDT chooses, the main thing is that the device qualitatively performs the required functions to protect not only the network, but also the owner’s life.