Electricity belongs to the technical achievements of mankind, without which life seems absolutely impossible to a contemporary. In order for it to enter the home of every user, an extensive network of high-voltage transmission lines is stretched across the country in all directions. The voltage acting in them is hundreds and thousands of times higher than the value of 220 volts necessary for household needs. The use of its increased value in power transmission lines makes it possible to economically "transfer" electrical energy from the place of its receipt (at a hydroelectric power station, for example) to a specific consumer.
Many users are well aware of the threat posed by high-voltage wires to a person in the vicinity. And for installers working on power lines, special protection will be required even when the line is disconnected from the substation. Many interested persons have a natural question: why do birds sit quietly on the wires of high-voltage lines, without any protection?
The essence of the problem
To answer the above question, you need to refer to the school physics course (see the section "Electrodynamics"). It follows from it that the electrical voltage is the potential difference at two remote points. When using a home socket, for example, there is such a gradient between its contacts. It is formed between the potential of the phase conductor (220 Volts) and zero: 220-0 = 220 Volts.
In a situation with birds on power lines, it is important to take into account not the absolute value of the potentials of the wires on which they are located, but their difference. The latter can be formed both between two wire lines and between each of them separately on the one hand and the ground on the other.
note: In this situation, the so-called "step" voltage (potential gradient) can be eliminated, since the distance between the birds' legs is very small.
Since the power lines are located at a considerable distance from one another, the possibility of touching two of them at once is completely excluded for birds. And it is absolutely impossible to imagine a situation where they simultaneously touch the wire and the ground with different parts of the body (as shown for the person in the photo below).
There is practically no current flowing through the bird's body
When placing birds on power lines, their body is connected through the legs in parallel with the piece of wire between them.
From the analysis of the simplest electrical circuit shown in the photo below, a number of conclusions follow:
- due to the fact that the internal resistance R of the bird's body is much higher than the same indicator for a short section of the power line wire - the current flowing through it is very small;
- as a rule, it is fractions of a microampere;
- with such a value of the branching current, the latter is not capable of any tangible effect (for such a small body).
All the above calculations and arguments are able to explain to a user who is very far from electricity, the reason for the safe location of birds on power lines.