The danger posed by electric shock is known to everyone. Here you can add the heating of the conductor, which occurs when there is a loose contact or short circuit. But without electricity, a person has not imagined his life for a long time, which means that ways to tame this force are needed. For this purpose, various protection devices were created, including automatic machines, the types of which we will consider today.
General characteristics of circuit breakers
Automatic devices are devices that can open the circuit in the shortest possible time in case of heating, short circuit or other emergency situations. With the right parameters of the device, there is no doubt that it will react to the slightest excess of the norms and remove voltage from the line, thereby protecting not only the person himself, but also his property.
Circuit breakers may differ in maximum current loads,number of poles or operating principle. Anyone who has come across such equipment knows that its body must be marked - B, C or D. The first type can be attributed to low-power devices, while the latter is used more often in industries where current loads are significant. For domestic use, choose the type marked C. The number after the letter is an indicator of the maximum current load, above which the device will trip. For example, a VA marked C16 will withstand 16 A without any problems, but if the indicator is exceeded, it will open the circuit and relieve the voltage.
Speaking about the types of circuit breakers, there are three main ones:
- BA.
- RCD.
- Difavtomat.
Let's try to analyze them in more detail to understand the purpose of protective devices.
Automatic switch: features, purpose
A device capable of opening a circuit in the event of a short circuit or network overload (overload of connected equipment). This is the main type of automata, which has 2 contacts (phase input / output) and works on the principle of an electromagnet, consisting of a solenoid and a rod, as well as a bimetal plate. It turns out that under normal current load, the release operates in normal mode, however, when it is exceeded, the stem is pushed out on the solenoid. He, in turn, rests against a bimetallic plate, which opens the contact.
These releases react not only tocurrent overloads, but also to an increase in external temperature, so poorly stretched contacts can cause periodic trips. They are also good at emergency shutdown in the event of a fire. But a more interesting type of electric circuit breakers can be called an RCD.
Residual current devices: differences from VA
The principle of operation of the RCD has completely different functions. There are 4 contacts on the case, 2 of which are for the input / output of the phase wire, and 2 for the neutral one. Such devices operate on the principle of potential difference. During normal operation of the circuit, the phase with zero is balanced and the RCD operates in normal mode. However, the slightest leakage of current creates an imbalance, and the device automatically turns off. For human protection, this type of machine is better than BA.
Let's take for example the breakdown of a phase wire on the body of any household appliance. Almost everyone knows how unpleasant sensations arise when touching metal in such a case. In this situation, as soon as a person touches the device, the RCD will turn off the power, and the reaction of the device is much faster than that of the VA. However, this type of automaton does not save from a short circuit - it simply does not respond to a short circuit, continuing to work.
For those who want to understand the operation of the RCD in more detail, below is a short video.
Video on "Residual current device"
It should be noted that both types of circuit breakers described above and performingcompletely different functions, optimally installed in pairs. Is it possible to get by with one device? Yes, easily.
Difavtomat: what is it, how does it work?
Quite often people don't want to mess with extra wiring in a switch cabinet, and sometimes there just isn't enough space to install all the protection systems that were planned. After all, if you look at it, on a DIN rail, the RCD takes up 2 modular places plus a circuit breaker - a total of 3. And if there are several power supply groups, besides, it is necessary to mount an introductory release, install an electricity meter? It turns out that you have to abandon any protection devices? Completely optional. Instead of RCD and VA, a difavtomat is installed, which combines the functions of both devices.
Such a device is capable of operating on excess current load, short circuit or leakage in the circuit. In size, it is similar to an RCD (2 places), and sometimes to a VA, which occupies one module. Often it is this factor that becomes decisive when choosing equipment, but the differential machine also has its drawbacks. Its cost is higher than that of a VA or residual current device, and if one of the parts fails, you will have to buy it entirely, while the release can be changed separately.
There is a lot of controversy among experts, what is better - separate protection or combined? Judging by the statistics, there are approximately the same number of supporters of difavtomats and their opponents. When solving thisThe question should be based on the possibility of installation. And if a differential machine is chosen, you should not save on the purchase. It is better to buy a quality branded device than periodically change cheap ones.
In conclusion
Protection of the power grid is necessary, anyone who has come across a similar issue will agree with this. But it’s not enough just to buy the first device that comes across and connect it. It is necessary to carefully calculate all the necessary parameters, weigh the pros and cons in relation to one or another type of machine, and only after that make a choice. The range of protective equipment for the home electrical network is quite wide, which means that the solution will not be easy. However, only a conscious, thoughtful and correctly made choice will help protect the life and he alth of loved ones, as well as the safety of property.
