Electricity is a very useful and at the same time dangerous invention. In addition to the direct effect of current on a person, there is also a high probability of fire if the wiring is not observed. This is explained by the fact that the electric current passing through the conductor heats it, and especially high temperatures occur in places with poor contact or during a short circuit. To prevent such situations, machines are used.
What are circuit breakers?
These are specially designed devices, the main task of which is to protect the wiring from reflow. In general, machines will not save from electric shock and will not protect equipment. They are designed to prevent overheating.
The technique of their work is based on opening the electric circuit in several cases:
- short circuit;
- excess current flowing through the conductor for this not intended.
As a rule, the machine is installed at the input, that is, it protects the next section of the circuit. Since different wiring is used for breeding for different types of devices, it means that the protection devices must be able to operate at different currents.
In appearance, it might seem that it’s enough to install just the most powerful machine and there are no problems. However, it is not. High current, for which the protection device did not work , can overheat the wiring and, as a result, cause a fire.
The installation of low power machines will break the circuit each time as soon as two or more powerful consumers are connected to the network.
What does an automaton consist of?
A regular machine consists of the following elements:
- Cocking handle. Using it, you can turn on the machine after it is triggered or turn it off to turn off the circuit.
- The mechanism of inclusion.
- Contacts. Provide connection and breaking of the circuit.
- Terminals Connect to the protected network.
- The mechanism triggered by the condition. For example, a bimetallic thermal plate.
- Many models may have an adjusting screw to adjust the nominal current.
- Arcing mechanism. Present on each of the poles of the device. It is a small chamber in which copper-plated plates are placed. On them, the arc is extinguished and disappears.
Depending on the manufacturer, model and purpose, the machines can be equipped with additional mechanisms and devices.
Trip mechanism device
The machines have an element that breaks the electric circuit at critical current values. Their principle of operation can be based on different technologies:
- Electromagnetic devices. They are characterized by a high speed of reaction to short circuit. Under the action of currents of an unacceptable value, a core coil is activated, which, in turn, disconnects the circuit.
- Thermal. The main element of such a mechanism is a bimetallic plate, which begins to deform under the load of high currents. Bending, has a physical effect on the element breaking the chain. The electric kettle works in approximately the same way, which can turn itself off when water boils in it.
- Semiconductor circuit breakers also exist. But in household networks they are used extremely rarely.
Types of machines according to current values
Devices differ in the nature of operation at an excessively high current value. There are 3 most popular types of machines - B, C, D. Each letter means the sensitivity coefficient of the device. For example, an automaton of type D has a value from 10 to 20 xln. What does it mean? It is very simple - to understand the range at which the machine is capable of working, you need to multiply the number next to the letter by the value. That is, a device marked D30 will turn off at 30 * 10 ... 30 * 20 or from 300 A to 600 A. But such machines are mainly used in places with consumers that have large starting currents, for example, electric motors.
An automaton of type B has a value of 3 to 5 xln. Therefore, marking B16 means tripping at currents from 48 to 80A.
But the most common type of machine guns is S. It is used in almost every home. Its characteristics are from 5 to 10 xln.
Legend
Different types of machines are marked in their own way for quick identification and selection of the right one for a particular circuit or its section. As a rule, all manufacturers adhere to one mechanism, which makes it possible to unify products for many industries and regions. We will analyze in more detail the signs and numbers printed on the machine:
- Brand Usually, the manufacturer’s logo is placed at the top of the machine. Almost all of them are stylized in a certain way and have their own corporate color, so choosing a product of your favorite company will not be difficult.
- Indicator window. Shows the current status of contacts. If a malfunction occurs in the machine, then it can be used to determine if there is a voltage in the network.
- Type of machine. As already described above, means the tripping characteristic at currents significantly exceeding the nominal. More often in everyday life, C is used and a little less often B. Differences in the types of automatic machines B and C are not so significant;
- Rated current. Shows the value of the current strength that can withstand a long load.
- Rated voltage. Very often, this indicator has two values written through a slash. The first is for a single-phase network, the second is for a three-phase network. As a rule, in Russia a voltage of 220 V. is used.
- Shutdown current limit. Indicates the maximum permissible short circuit current at which the machine will shut down without failure.
- Current limit class. It is expressed in one digit or absent altogether. In the latter case, it is customary to consider the class number 1. This characteristic means the time for which the short circuit current is limited.
- Scheme. On the machine you can even find a connection diagram of contacts with their designations. It is almost always located in the upper right part.
Thus, looking at the front of the machine, you can immediately establish what type of current it is intended for and what it is capable of.
What type of machine to choose?
When choosing a protective device, one of the main characteristics is considered to be the rated current. To do this, you need to determine what current strength requires the combination of all consumer devices in the house.
And since electricity flows through the wires, the current necessary for heating depends on its cross section.
The presence of poles also plays an important role. The most common practice is:
- One pole. Circuits with lighting devices and sockets to which simple devices will be connected.
- Two poles. It is used to protect wiring conducted to electric stoves, washing machines, heating devices, water heaters. It can also be installed as protection between the shield and the room.
- Three poles. It is used mainly in three-phase circuits. This is true for industrial or near-industrial premises. Small workshops, production and the like.
The tactics of installing automatic machines comes from larger to smaller. That is, it is first mounted, for example, bipolar, then unipolar. Next come devices with power decreasing at every step.
Some tips for choosing a machine
- When choosing, it’s worth focusing not on electrical appliances, but on wiring, since it is precisely it that the circuit breakers will protect. If it is old, it is recommended to replace it so that you can use the most optimal version of the machine.
- For rooms such as a garage, or for the duration of the repair work, it is worth choosing a machine with a nominal current larger, as various machines or welding machines have quite large current indicators.
- It makes sense to complete the entire set of protective mechanisms from the same manufacturer. This will help to avoid the mismatch of the rated currents between the devices.
- Buying machines is better in specialized stores. So you can avoid buying a low-quality fake, which can lead to disastrous consequences.
Conclusion
No matter how simple the layout of the circuit in the room may seem, you always need to remember safety. The use of automatic machines helps to a large extent to avoid overheating and, as a consequence, its ignition.