Electricity. Current Power

The study of electricity as a physical phenomenon begins with the school bench. Many teachers, in order to simplify the understanding of the students of the material presented, resort to comparing the electric current in the conductor with the motion of the liquid through the pipe. And although this comparison is approximate, it is possible to describe schematically all the processes connected with the phenomenon of electricity as a whole and the flow of electric current in the conductor in particular. But, as practice shows, it is much easier to master all the subtleties of this vast section of physics, if we immediately consider the actual processes taking place without trying to find them an analogue in the world of mechanical phenomena.

To describe the electrical phenomena occurring in conductors, use a whole set of different values and parameters. Of course, for the practical application of electricity we are interested in the power of the current, but to determine this parameter one has to become acquainted with other basic characteristics of the flow of electricity in the conductor.

Strength is one of the important characteristics of the action of electric current. In terms of its physical meaning, it shows the amount of electricity (charge value) that passes the electric circuit per unit time. For this purpose, the value of the electric charge passing through the cross section of the conductor per unit time is taken into account. In mathematical form, this value looks like a pendant (Cl) divided by a second (c). The current ampere (A) is taken as the current measurement unit .

The next parameter that is taken into account when the current is calculated is the voltage. Considering the fact that an electric current is an ordered movement of particles having a charge, an electric field is necessary to create this motion. So, to determine the voltage value, calculate the ratio of the work of the current on a particular section of the circuit to the charge flowing through it. For the voltage unit, it was decided to take the volt (B), which is physically equal to the ratio of the unit of work J to the unit of charge Kl.

Using an ammeter connected to the circuit in series, we determine the magnitude of the current, and the voltmeter connected in parallel - the voltage. The power of the current is determined analytically, multiplying the force by the voltage. Taking into account the previously accepted physical definitions of the parameters, we obtain the power unit J / s or one watt (W). In practice, we considered an example of calculation in the ideal case, in which the direct current power was determined .

That's just often in everyday practice we are dealing with a three-phase current. We determine the power of the three-phase current as the sum of the powers of each individual phase. Taking into account that each of them works in the alternating current mode, the power factor cos j is added to the power calculation.

Having calculated the total current capacity for different ways of connecting the load for a three-phase current (and we know them two by a triangle and a star) we find that, after simple mathematical transformations, the formula for calculation in both cases assumed the same form. To the product of the voltage on the linear current and to the load power factor cos j, a factor equal to the square root of three (or in approximate calculation 1.73) is added.

Having studied the concept of "current power", it is worth recalling the existence of two of its main types. Transformation into other types of energy is characteristic of active electric power . It can be light, thermal, mechanical and others. Watts, kilowatts, megawatts are used for the measurement.

When considering reactive electrical energy is meant a value, which is characterized by electric load, is created by consumers of the energy of oscillation of the electromagnetic field. Often this type of energy is characteristic of engines. As a unit of measurement take volt-ampere reactive (VA).