In the modern world, we are surrounded by such a huge number of different technical devices that we simply do not notice some of them. This statement may seem unbelievable, but anyone can be convinced of this at any time. It is enough, for example, to try to remember which trees grow around a high-rise building. Or say exactly how many steps there are on a flight of stairs. Most will fail.
Ah, after all, we encounter these things thousands of times. This is explained very simply: the mind unloads itself, interacting with some things without focusing attention. Needless to say, the circuit breaker - this essential element of almost all electrical circuits - turns out to be a "dark horse".
Invisible helper
Once I happened to witness an amazing situation: a person with a higher education, who had years of experience working with electrical installations, purchased 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 broken not by an automatic switch, but by a toggle switch on a chain, similar to thosewhat is installed in wall lamps - sconces. Not surprisingly, after a short period of time, everything in this switch burned out. So, today we will talk about how to choose a circuit breaker, what they are and what they are for. After all, if a person whose speci alty is electrical engineering thought of this, then what can be expected from the rest?
Indispensable circuit breaker
Let's see why it's called that. The word "switch" is known to everyone - this is a device that provides the ability to switch an electrical circuit. Click the toggle switch and the light in the room lights up, click again 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" indicates that the device in some cases can turn itself on or off. Usually the circuit is open. Inside the case there are two mechanisms that constantly monitor the amount of current and, if it increases excessively, turn off the circuit breaker. The first is a thermal release. It is represented by a bimetallic plate, which, when heated, bends and resets the return mechanism from the latch. The second is magnetic. Made in the form of an inductor, which with its magnetic field (if the current is too high) breaks the circuit in the device.
Types of "machines"
Depending on the number of switched lines, one- and multi-pole devices are distinguished. That is,by moving one toggle switch, several circuits can be activated at once.
For example, a two-pole circuit breaker installed in an apartment electrical panel protects connected branches from overload and heat (thermal release), as well as from short circuits (magnetic setting).
Choice
Thus, the selection of the "machine" is carried out according to the rated current. This value is always indicated on the case. It should not be less than in the line that this device will switch and protect. By the way, this is why simple toggle switches cannot be installed on powerful equipment, since the amount of current flowing is too high.
The number of poles is selected individually. Here you need to take as much as you need. 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 breaking ratio. "B" will break the circuit when the current increases by only 3-5 times, but the popular class "C" will work already at ten times the nominal value.
