Walking currents are understood as the directed movement of electronic charges that appears in conductors due to the action of extraneous electrical forces. In the practice of operating power grids, this effect is classified as a very undesirable phenomenon, leading to their accelerated destruction.
That is why it is extremely important to become familiar with the features of this phenomenon and methods of dealing with it.
What is this effect and what are its features
It is known that the main condition for the flow of charge in a circuit is the presence of a difference in electrical potentials at two points separated by a conducting medium. The so-called "stray currents" are precisely formed according to this principle in a situation when either the ground or the metal structure in it is used as a conductor.
Reasons for the appearance
The life of modern megalopolises with a system of transport and other communications is impossible without a developed network of electrified facilities. The latter include:
- Local supply substations with power lines departing from them.
- Electrified routes (electric trains, metro, etc.).
- Underground cable lines for lighting networks.
All these energy objects, as a rule, are located deep in the ground, which is the reason for the appearance of a potential difference at different points. And this initiates wandering currents undesirable for human needs.
Principle of education
It was noted that for the formation of a potential difference, electrical networks are optimal, in which not an isolated, but a tightly grounded network neutral is provided.
With such an organization of protection, the neutral conductor PEN is connected at one end to the memory at the substation, and at the other end to the grounding bus in the consumer equipment. In this case, the entire load current will flow along the path where the resistance is minimal (photo below).
A necessary and sufficient condition for its destructive effect is damage to the insulation of working cables laid deep in the ground. From this moment, undesirable phenomena begin to occur in them.
Danger of stray currents and protection methods
The humid environment with dissolved salts already has a destructive effect on the metal in the ground. In the event that the metal cable being laid is in the path of stray charges, they will flow along the path where the resistance is less (that is, along its steel braid).
Note: In this case, it acts as an electrode that leads currents to the ground.
At the same time, the effect of moisture and salts on the braid only increases (due to a combination of hazardous factors), which ultimately leads to an acceleration of its destruction.
How to protect yourself from stray currents
There are two proven ways to protect against this phenomenon. The first of them refers to passive methods and involves the application of a special material to the protected product that insulates the metal from the action of aggressive media. This function is performed by such polymer compounds as epoxy resin or bitumen impregnation. Greater efficiency can be achieved by using active protection, which consists in installing an additional metal structure next to the controlled object. The latter performs the function of an anode, "distracting" stray currents (photo below).