What is the stray currents, their harm and ways to protect

Have you ever heard such an expression as "Stray currents"? Not? So here is the directional movement of charged particles that occurs in a natural conductor. And in fact it is a very dangerous and very undesirable. In this article I will discuss how they appear and how to struggle with them. So there you go.

What is the stray currents and how they are formed

All we all know that the condition for the formation of an electric current is the presence of the difference potential between the two points and the presence of specifically designed for power transmission conductor.

So, stray currents are formed on the same principle, except that the energy transport uses natural conductor (earth) or metal structure placed in the ground.

With the principle of occurrence of these currents just like everything, now let's find out what shapes them.

Sources of stray currents

If you and I look at the modern metropolis, we find there is a huge amount of electrified objects ranging from large supply substations with power feeders, finishing train and underground.

And all of these energy facilities are located on the ground or under the ground, which, of course, leads to a rather complex interaction across the land and the formation of stray currents.

The above table shows the main sources of stray currents, let us for a better understanding of the mechanism of formation look at an example.

Thus, to form dots with different potentials are ideal grounding circuit in a system with solidly earthed neutral.

In this case the neutral conductor PEN on the one hand it is connected to storage at the substation, and the other to the ground bus by the consumer.

Of course, practically the entire load load will follow the path of least resistance, that is, zero conductor, but a small part will still flow into the ground loop, and will-o'-current.

Damage to the insulation of cables laid in the ground also create conditions for the formation of these currents. Well, they were formed and what's next? But then the fun begins.

The effect of stray currents in the metal

Tell me, what happens to a piece of metal, if it is buried in the ground? Right, under the influence of moisture and dissolved salts triggered corrosion process.

A current is created and sent VITP from one ground to the other, and if the metal will appear in his way It objects, then current flow is wandering on it, since the metal has a much smaller resistance than priming.

A combination of: dissolved salts, and the electric current flowing metal (playing the role of electrodes) trigger the electrolytic process, and the flow rate of the electrochemical reaction, according to Faraday's law, is directly dependent on the magnitude of the current flowing between the anode and cathode.

This means that the rate of corrosion, e.g., metal water pipe will have influence the electrical resistance of soil and complex processes taking place in the anodic and cathodic area.

What happens in the cathode-anode zone

So, our current on the ground has reached the metal tube and found "entry point" (free electrons flow into the conductor), this area is called the cathode and the metal structure is not threat.

But our current continues the way to the other pole of the potential differences and sooner or later comes out of the metal back into the soil, so that's the exit site of the vagus current is called the anode area and the emitted electrons are "washed" the metal atoms in the art, thereby greatly accelerating the process of Corrosion.

And pipes, which should by all standards to serve at least 20 years old in a couple of years can buy this kind of

How to protect against stray currents

As you know stray currents are extremely dangerous and undesirable, and from it there are two methods of protection:

1. Passive protection.

2. Active protection.

passive protection

Thus, for passive protection, for example, include applying to the conduit pipe special insulating material which shuts the metal from an aggressive environment. As the insulation commonly used variety of polymeric compounds, epoxy resins, bitumen impregnation, etc.

But such isolation does not provide absolute protection, and during installation and during operation can damage the skin and thus the corrosion process will proceed in this place is very intense.

Much more effectively showed itself active protection

active protection

In this embodiment, protection is taken under the control of the flow process originally uncontrollable stray currents. It uses a cathodic polarization, in which the negative potential shifts natural.

And depending on the resistance of the soil used galvanic method or applied DC current.

In the first embodiment, a so-called "sacrificial" anode, which assumes all the vagus current, thereby preserving fracture from protected metal structure. But this option is used for soil resistance not exceeding 50 ohms per meter. If the resistance is greater than this value, a DC power source.

Active protection permits better protection of metal structures, located in the ground.

That's all I wanted to tell you that such stray currents, how they are formed and how they are fighting, if the article was useful to you, you will appreciate its Like and do not forget to subscribe to channel. Thanks for your time, good luck and prosperity!