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Interaction of currents in parallel conductors

The interaction of currents is very well known in modern electrical engineering: it is taken into account in the design of complex nuclear reactors of the Tokamak type and in the designs of electric motors. For example, in the latter, displacement of the nearby coils of the stator winding to the winding of the rotor is observed. Thus, with the "heavy" start-up of powerful machines, when the current reaches the maximum permissible values, damage to the holding coils may be observed. In this case, there is a magnetic interaction of the currents flowing through two different windings. Their rotating magnetic fields exert an attractive effect on the conductors. Studying the interaction of currents, they usually consider the magnetic type of interaction, although in fact this topic is more extensive.

Let's imagine a three-phase network, to each line of which its own group of consumers is connected. While their total resistances are approximately equal, the entire system works steadily, but it is essential to violate the current balance, as a regime called "phase bias", capable of disabling equipment, comes. Also, the interaction of currents occurs with the parallel inclusion of several power supplies for the same load. In this case, if the phasing is done correctly, the currents flow between the sources (for a short time), but with a mismatch of the phase lines, a short circuit occurs. It is obvious that the interaction of currents manifests itself in different ways. Yet most often it is customary to consider Ampere's Law.

If a movable frame is inserted between the opposite poles of the magnet (a constant magnetic field), through which the current passes, it will turn to an angle determined by the interaction force between the two magnetic fields and the direction of the tension lines. This force was defined and formulated in 1820 by the famous French physicist AM Amper.

At the present time, the following formulation is used: when a current flows through a thin-section conductor in a magnetic field, the force dF, which acts on a certain wire segment (dl), is directly related to the current I and the vector product of length dl by the value of the magnetic induction B. That is:

DF = (I * dl) * B,

Where F, l, B are vector quantities.

Determination of the direction F is usually carried out in a very simple way - the rule of the left hand. Mentally, the left hand should be positioned in such a way that the magnetic induction lines (B) enter the open palm at an angle of 90 degrees, 4 straightened fingers indicate the current direction (from "+" to "-"), then the right thumb The direction of the Ampere force acting on the current conductor.

The most common force is the interaction of parallel currents. In fact, this is a special case of a general law. Let us imagine two parallel conductors with a current in a vacuum, the length of which is infinite. The distance between them is denoted by the letter "r". Each conductor (currents I1 and I2) generates a magnetic field around itself, so they interact. Induction lines are circles.

The direction of the vector of magnetic induction B1 is determined by the rule of the borer. We give the formula:

B1 = (m0 / 4Pi) * (2 * I1 / r);

Where m0 is the magnetic constant; R is the distance; Pi - 3.14.

Applying the formula for finding the Ampere force, we get:

DF12 = (I2 * dl) * B1;

Where dF12 is the force of action of the field of conductor 1 on conductor 2.

The strength module is:

DF12 = (m0 / 4Pi) * (2 * I1 * I2 / r) * dl.

If the length l is equal to zero to one, then:

F12 = (m0 / 4Pi) * (2 * I1 * I2 / r).

This is the force that acts on a certain unit of the length of the wire with the current. If you know the value of F, it becomes possible to design reliable electrical machines that provide for the action of Ampere's force. It is also used to calculate the value of the magnetic constant. It is necessary to pay attention, that, proceeding from a rule of the left hand, follows: if the direction of currents coincides, the conductors are attracted, and otherwise - repelled.

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