What is an electric arc as it is formed and where used

During switching operations, and when the phenomenon as overvoltage between live parts may be formed arc. In addition to the destructive and negative impact of this phenomenon is also learned to use the benefit. In this article I will talk about what is the electric arc, and how it is now used. Let's get started.

As the electrical arc is formed and has the properties that

If we take two electrodes to fix them at a small distance from each other, and so that the sharp ends were directed towards each other and connect them to the regulated power supply, the voltage is gradually increased, we see that when a certain voltage first encounter sparks, and then formed a stable combustion arc.

The resulting glow - it is nothing more than a plasma. In fact this is the arc, or otherwise the flow of electric current through the gaseous medium (air).

The figure above shows the current-voltage characteristic and the structure of the arc.

A combustion temperature (in the approximate range) as follows:

Causes of arc

Now let's look at why an electric arc (continue to look at all the same example with the electrodes). In fact, everything is very simple. If absolutely any object having a certain conductivity, placed in an electric field, begin to form and accumulate the charges on the surface thereof.

Thus, less than a radius of curvature will have a body, the more charge will be formed in this location.

Simply put, the charge accumulated on the sharp edges. Since the electrodes have air (gas mixture), then under the action of the same electromagnetic field ionization process begins. Thus creating conditions for the formation of an electric arc.

The magnitude of the voltage at which breakdown of the air gap is carried out, depends on many factors.

Apart from increasing the voltage between the electrodes, another condition is formation of arc gap mains contacts. If the chain is present large inductance, the switching of the law, the current can not be interrupted at one point. This means that the arc between the disconnected contacts will remain illuminated as long as the power goes off or dissipated by the accumulated energy in the magnetic field of the inductor.

Conditions of ignition and arc

So with that as the arc is formed seems to be sorted, let's say in thesis about the conditions and the ignition of the arc.

In order to form an arc between the electrodes need to space was filled with gas. After all, to realize the gas sample, the voltage must be increased to a few thousand volts, and for combustion maintaining sufficient tension in the 50-60 Volts, well, the current value thus should not be less than 10 amperes.

The electric arc is harmful and how to fight it

The arc is harmful especially in that it destroys the contacts between which it is formed. All this is due to the fact that during combustion is allocated a very large amount of heat, which is quite simply melts contacts.

To minimize the harmful effects of arcing in switching devices use a variety of devices. For example, in the networks of 0.4 kV to extinguish the arc using special interrupters.

The principle of operation of such a chamber is as follows: when disconnecting the arc formed curving regard plates arc chute, thereby being divided into several smaller arcs, as a result, they rapidly cool and disappear.

In networks above 1 kV uses special switches:

- oil;

- vacuum;

- sulfur hexafluoride.

The arc extinguishing oil circuit occurs as follows: the contacts are switched in the oil environment, so when the connection arc starts burning in oil, which is decomposed into hydrogen and attendant gases.

At the same time formed a bubble endeavor as quickly as possible to escape from the chamber. Thereby stretching the arc and, since hydrogen has excellent thermal conductivity, it simultaneously cools the arc. And so it just goes out.

In the vacuum circuit breakers contacts are in an airless environment, ie, the ionization process is in principle impossible, since there is no medium.

In the gas-insulated circuit breakers is the opposite: the gas (sulfur hexafluoride) is under high pressure. Shaped pressure prevents ionization.

The arc and its useful application

The destructive power of the electric arc, and learned how to use the benefit.

And, perhaps, the first thing that comes to mind - it's electric welding. Just welding machines and used principle stable combustion at a low arc voltage.

As the arc is used as the light source in Dugo discharge lamps.

In addition, there are special dugoplavilnye furnace.

conclusion

That's all I wanted to tell you about an electric arc, its destructive force and the peaceful use. If the article was useful to you, you will appreciate it Like. Thank you for your attention!