In the modern world, we are surrounded by such a huge number of different technical devices that we simply don’t notice some of them. This statement may seem improbable, but everyone can be convinced of it at any moment. It is enough, for example, to try to remember which trees grow around a high-rise building. Or to say exactly how many steps on a flight of stairs. Most will fail.
But, after all, with these things we come across thousands of times. This is explained very simply: the mind unloads itself by interacting with some things without focusing attention. Needless to say, the
circuit breaker - this necessary element of almost all electrical circuits, turns out to be a "dark horse".
Stealth assistant
Once I happened to witness an amazing situation: a person with a higher education, whose work experience with electrical installations was estimated for years, acquired a modern washing machine and, deciding to make working with it more convenient, without further ado, connected it to the network through a switch. The idea is really good. But the circuit was not broken by an automatic switch, but by a toggle switch on a chain, similar to those installed in wall lamps - a sconce. It is not surprising that after a short period of time everything in this switch faded. So, today we’ll talk about how to choose a circuit breaker, what they are and what they are for. Indeed, if a person whose specialty is electrical engineering has thought of such a thing, then what can be expected from the rest?
Irreplaceable circuit breaker
Let's see why it is so called. The word "switch" is known to everyone - it is a device that provides the ability to switch an
electrical circuit. A click of the toggle switch - and the light in the room lights up, a second click - and everything goes out. When the light is on, the switch passes current through itself. In part, it can be compared to a ball valve in a water supply system.
But the word “automatic” means that in some cases the device can turn itself on or off. Normally the circuit opens. Inside the case there are two mechanisms that constantly monitor the magnitude of the current and, when it is exaggerated, turn off the circuit breaker. The first is a thermal release. It is represented by a bimetallic plate, which, when heated, bends and discards the return mechanism from the latch. The second is magnetic. It is made in the form of an inductor, which breaks the circuit in the device with its magnetic field (if the current is too high).
Types of "machines"
Depending on the number of switched lines, there are single and multi-pole devices. That is, with the movement of one toggle switch-tongue, you can use several chains at once.
For example, a
two-pole circuit breaker installed in an apartment electrical panel protects the connected branches from overload and heating (thermal release), as well as from a
short circuit (magnetic setting).
The choice
Thus, the selection of the "machine" is performed at the rated current. This value is always indicated on the housing. It should not be less than in the line that this device will switch and protect. By the way, this is why it is impossible to install simple toggle switches on powerful equipment, since the magnitude of the flowing current is too high.
The number of poles is selected individually. Here you need to take as much as necessary. Some models allow you to combine cases into a single unit, increasing the number of switched lines.
Type (B, C, D) indicates the short-circuit current cut-off factor . “B” will break the circuit when the current increases by only 3-5 times, but the popular class “C” will work even when the rating is ten times higher.