POWER ELECTRIC

value characterizing the rate of change (transformation, dispersion, transmission, etc.) electric. energy. In chains post. current M. e. is equal to the product of Voltage and current. In AC circuits current distinguish between instant, active, reactive and full M. e. Instant M. e. is equal to the product of instantaneous voltage and current values. Active M. e. - the average value of the instantaneous power over the period. current; characterizes cf. electromagnet conversion speed. energy into other types of energy (thermal, mechanical, etc.). In single-phase AC circuits current (sinusoidal) active M. e.

P \u003d U I cos f, for a three-phase current P \u003d root of 3UI cos f (U and I are the effective values \u200b\u200bof voltage and current, f is the phase shift between the current and the voltage). Active M. e. can be expressed in terms of current I or electric. voltage U and active resistance circuit r or its conductivity G according to the formula: P \u003d I 2 r \u003d U 2 G. In any electric. chains active M. e. is equal to the sum of active M. e. dep. sections of the chain. Unit active M. e. - W (see. Watt). Reactive M. e. characterizes the rate of energy storage in capacitors and inductors, as well as the exchange of energy between separate. sections of the circuit and, in particular, the generator and the receiver. In the circuits of sinusoids, the current is reactive M. e. section O \u003d\u003d U * sinf. Unit reactive M. e. - var. Full M. e. characterizes M. e., given to the circuit by a source of AC. current. For sinusoidal circuits, the current is full M. e. S \u003d UI\u003d root of (P 2 + Q 2). Unit complete M. e. - volt-ampere (VA).

Big Encyclopedic Polytechnic Dictionary. 2004 .

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POWER electric, work electric current per unit of time. In the chain direct current power is equal to the product of voltage and current. In an alternating current circuit, a distinction is made between full power (see TOTAL POWER) active power (see ACTIVE ... ... encyclopedic Dictionary

POWER ELECTRIC - the power of the electric current, i.e. the work of the electric current per unit of time. It is measured in watts (see) (W) or units derived from watt: hectowatts (1 GW \u003d 100 W), kilowatts (1 kW \u003d 1000 W). It is designated by the letter R. Fee with ... ... Brief Encyclopedia of Household

See Electric power ...

Electric work of electric current per unit of time. In a DC circuit, power is equal to the product of voltage and current. In an alternating current circuit, a distinction is made between full power, active power, reactive power … Big Encyclopedic Dictionary

See Electric power. * * * ELECTRIC POWER ELECTRIC POWER, see Electrical power (see POWER (electrical)) ... encyclopedic Dictionary

See Power electric ... Natural science. encyclopedic Dictionary

Dimension L2MT − 3 SI units W CGS ... Wikipedia

Power is a physical quantity equal to the ratio of the work performed during a certain period of time to this period of time. Effective power, engine power delivered to the working machine directly or through the power train. ... ... Wikipedia

Electr. current per unit of time (1 sec.). Measured in watts or kilowatts. At constant current, the power (in watts) is equal to the voltage (in volts) multiplied by the amperage (in amperes); with single-phase alternating current, the actual, or ... ... Technical Railway Dictionary

Electromagnetic energy is a term that refers to the energy contained in an electromagnetic field. This also includes special cases of pure electric field and clean magnetic field... This energy is mechanical work, ... ... Wikipedia

Power of Electric Current and its Work.
Basics of Electricity.

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Any electrical machines, equipment, installations, devices that are driven, heat, radiation, conversion, etc., electricity are direct consumers of electricity. The more electricity, every second, the installation needs, the greater the volume of its work.

The most important characteristic of various electrical systems is the power consumption (power of the electric current). Electric power characterizes the amount of consumed electricity for a certain period of time. In order to know the power of the electric current of the installation, multiply the voltage at which the installation works by the strength of the current passing through this installation.

Let's find out why this is the case. As many should already know, the voltage (difference electrical potentials), supplied to the electrical equipment, characterizes what kind of work the electromagnetic field does, moving one pendant of electricity through this installation. The strength of the current expresses the number of coulombs passing in 1 second.

If we multiply the work done on each charge by the total amount electric chargesthat have passed in one second, then as a result we will find out the general work done electromagnetic field in this second. And this, in turn, will be the consumed electrical power of the installation. Due to this electricity consumed every second, as a result, the useful work of this installation (system, equipment, device) is performed.

Power (W) \u003d Amperage (A) * Voltage (V)

Electrical power (the power of an electric current) is usually measured in watts (for powerful systems, it is measured in kilowatts). One watt is the electrical power released on a conductor when the electric field voltage at the ends of this conductor corresponds to one volt, and the strength of the electric current on this conductor is one ampere. Remember that in 1 kW (kilowatt) \u003d 1000 W (watt).

let's consider next example: 1 amp current flows through the flashlight. The potential difference (voltage) of the power supply of this flashlight is 12 volts. If the voltage is multiplied by the current strength, then we get the power of the flashlight: 12V * 2A \u003d 24 W.

The electrical power of an electrical installation or device characterizes how much electrical energy consumed in a certain unit of time, namely in one second. The total amount of this energy that is consumed by the installation for a certain time, we will find out with you if we multiply the electrical power of the installation by the period of its operation:

Work (J) \u003d Power (W) * Time (s)

This value indicates the amount of work that has been done by the installation over a certain period of time. If all the electrical energy expended was spent on useful work, then, multiplying the time by the power, we would find out the amount of this work that the electrical installation did (for example, an electric motor on a crane). But, unfortunately, part of the electrical energy is usually spent on overcoming the frictional force of various moving parts of the electrical installation, on heating the working winding and other work. For this reason, the useful work of the electrical installation is somewhat less than the total electrical energy it consumes. The ratio of the absorbed energy to the useful work is called the coefficient of performance (efficiency).

As a rule, in technology, work and energy are measured in kilowatt-hours. One kilowatt hour is the energy consumed in one hour by an electrical appliance with a capacity of one kilowatt. The electrical power is always indicated, both on the device itself (on the case) and in the accompanying passport documentation.

There are several basic parameters for measuring electric current. The most important are current and voltage. Current is the movement of electrons in a conductor, voltage - this is what sets them (electrons) in motion. However, for a complete description of all parameters, we will also talk about such characteristics as power, resistance and frequency, which we will talk about when we define alternating current.

Current strength- the measured physical quantity, which is equal to the ratio of the amount of charge passing through the conductor in a certain time (more precisely, its cross section) to the value of the specified time interval. As we know, current strength is measured in Amperes (A).

Electric voltage called the ratio of the work of the current to the charge in a certain section of the circuit. The current charge is measured in Coulomb (C), and the work is in Joules (J). Thus, the voltage can be measured as follows: 1J / 1C. The resulting value will be equal to 1 Volt (V) - the basic unit in which voltage is measured.

Current power is called such work, which is performed by particles of electric current against electrical resistance... We see the results of this work in the released thermal energy. Therefore, to put it simply, the power of an electric current is the amount of heat generated per unit of time. The power is measured in Watts (W).

Electrical resistance. At one time, the German scientist Georg Simon Ohm noticed that devices produce different amperage when using different electrical circuits... Thus, it has been proven that different conductors have different electrical resistance. The formula for calculating resistance is simple. We mark the resistance itself with the letter R, L will denote the length of the conductor, and S will denote the cross-sectional area. In this case, the resistance is calculated using the formula R \u003d L / S. The resistance is measured in Ohms.

Resistance determines how much the material prevents the flow of electric current. The higher the resistance, the more voltage is needed to provide the required current.

Electrical voltage affects how carefully the conductors should be insulated. The higher the voltage, the greater the chance of insulation breakdown. Higher voltages require more reliable insulation. Bare wires with higher voltages should be placed farther apart, away from other conductive materials, and away from earth.

Higher voltages are more dangerous. But one should not think that low voltage is completely safe. The damage to health from electric shock depends on the strength of the current that has passed through the body and its trajectory. And the current strength already depends on the voltage and resistance. The resistance of the human body is determined by the resistance of the skin. Internal organs and environments conduct current well. Skin resistance can change tenfold depending on the emotional state, physical activity, humidity and a dozen other factors. Cases of fatal 12-volt electric shock reported... The strength of the electric current determines which wires to use. The higher the amperage, the thicker the wire is needed.

The power of the electric current is measured using a wattmeter. One of the terminals of the current winding must be connected to one of the terminals of the voltage winding. These terminals in the instrument are connected to terminals marked with an asterisk. Therefore, before turning on the wattmeter and the circuit, first, using an insulated wire of a short length, the terminals marked with an asterisk are connected. Power in DC circuits, as well as in AC circuits in the absence of capacitors and electrical receivers with windings (for example, motors) in them, can also be measured indirectly: using an ammeter and voltmeter. According to the readings of the ammeter and voltmeter, the power is calculated using the formula known from physics.

End of work -

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Measuring instruments can be classified according to two criteria: design; metrological purpose

CLASSIFICATION OF MEASUREMENTS ... A measuring instrument is a technical instrument or a complex of them ... Other distinctive features of measuring instruments are, firstly, the ability to store or reproduce a unit ...

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