The danger posed by electric shock is known to everyone. Here you can add the conductor heating that occurs when the contact is loose or short circuit. But without electricity, a person has long been unable to imagine his life, which means that ways of taming this force are needed. For this purpose, various protection devices were created, including automatic devices, the types of which we will consider today.
General characteristics of circuit breakers
Automata are devices that are capable of opening the circuit in the shortest period of time in the event of heating, short circuit, or other emergency situations. With the right parameters of the device, you can be sure that it will respond to the slightest excess of norms and relieve tension from the line, thereby protecting not only the person himself, but also his property.
Circuit breakers may vary in terms of maximum current loads, number of poles or tripping principle. Everyone who has encountered such equipment knows that it must be labeled 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 a type with the marking C. The number after the letter is an indicator of the maximum current load, after which the device will trip. For example, a VA with the marking C16 can easily withstand 16 A, but if the indicator is exceeded, it will open the circuit and remove the voltage.
Speaking about the types of circuit breakers, three main ones can be noted:
- VA.
- RCD.
- Difavtomat.
Let's try to disassemble them in more detail in order to understand the purpose of the protective devices.
Automatic switch: features, purpose
A device that can open the circuit during a short circuit or network overload (oversupply of connected equipment). This is the main type of automatic machines, 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 the normal mode, however, when it is exceeded, the rod is pushed out on the solenoid. He, in turn, abuts against a bimetallic plate, which opens the contact.
These releases respond not only to current overloads, but also to an increase in external temperature, so poorly drawn contacts can cause periodic trips. They also handle emergency shutdowns in the event of a fire. But a more interesting type of electric circuit breakers can be called 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 input / output of a phase wire, and 2 are for zero. 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 the normal mode. However, the slightest leakage of current creates an imbalance, and the device automatically turns off. To protect humans, this type of machine is better than VA.
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 a metal in such a case. In this situation, when a person touches the device, the RCD will turn off the power, and the response of the device is much faster than that of the VA. However, this type of machine does not save from a short circuit - it simply does not respond to a fault, continuing to work.
For those who want to understand the work of the RCD in more detail, below is a short video.
Video on the topic "Residual current device"
It should be noted that both types of circuit breakers, described above and performing completely different functions, are optimally installed in pairs. Is it possible to do with one device? Yes easily.
Difavtomat: what is it like, how does it work?
Quite often, people do not want to mess with unnecessary switching in the control cabinet, and sometimes there is simply not enough space to install all the protection systems that were planned. Indeed, if you look, on a DIN rail, an UZO takes up 2 modular places plus a circuit breaker - a total of 3. And if there are several power supply groups, you also need to mount an input release, install an electricity meter? It turns out that you have to abandon any protection devices? Absolutely optional. Instead of RCD and VA, a difavtomat is installed, which combines the functions of both devices.
Such a device is capable of triggering an excess of 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 a differential machine also has its drawbacks. Its cost is higher than that of a VA or residual current circuit breaker, and if one of the parts fails, you will have to buy it entirely, while the release can be changed separately.
There are many disputes among experts, which 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 this issue, it is worth starting from the possibility of installation. And if you choose a differential machine, you should not save on acquisition. It’s better to buy a quality branded device than to periodically change cheap ones.
Finally
Electricity protection is necessary, anyone who has faced a similar issue will agree with this. But it’s not enough just to purchase the first device you get and connect it. It is necessary to carefully calculate all the necessary parameters, weigh the pros and cons in relation to a particular type of machine and only then make a choice. The range of protective equipment of the home electrical network is quite wide, which means that the decision will be difficult. However, only a conscious, thoughtful and correctly made choice will help protect the life and health of loved ones, as well as the safety of property.