U phase. Phases and linear streams and voltages. Numerical correlation between phase and linear values

Three-phase lances are made up of three main elements: a three-phase generator, transmission lines with the necessary equipment, priymachiv (spozhivachiv). The voltage between the line wire and the neutral (Ua, Ub, Uc) is called fazim. The voltage between two line wires (UAB, UBC, UCA) is called linear. For winding windings with a star, with a symmetrical winding, it is fair to apply between linear and phase streams and voltages:

13. Symmetrical and non-symmetrical primaries in triphasic lancets, vector diagrams.

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Vector diagram when catching a star with a flash symmetrical aiming .

14. Strum in neutral dross in triphasic lancers. Neutral (zero working) conductor- Provid, which is connected between the neutrals of electrical installations at three-phase electrical lines. When connecting the windings of the generator and receiving electricity for the “star” circuit, the phase voltage is deposited as a voltage, which is connected to the skin phase. At the time of the connection, for example, three-phase motor, the drive will be symmetrical, and the voltage between the neutral points of the generator and the engine will be equal to zero. However, as far as the skin phase is connected, there is a difference of interest, in the vinyl system it is called neutral voltage, which reveals the asymmetry of the drive voltage. In fact, it can be brought to the point that part of the mother’s life is reduced, and part is increased. The voltage has been reduced to the point of incorrect operation of the connected electrical installations, and it can be increased, of course, to bring the electrical supply to the point of failure or failure later. Z'dnannya neutral point of the generator and receiving electricity with a neutral drotom allows you to reduce the voltage of the neutral neutral practically to zero and to change the phase voltage on the receiving of electricity. A small voltage will be wised up only by the support of the zero dart.

Triphasic lancers with a neutral drote are called chotiripid lancers.

Sound the support of the wires are not insured.

e.g. priymacha dorivnyuyut fasn. generator voltage. .

For those who have complex support equals, then the strumi are signified

Vіdpovіdno up to 1 order. Kirgof strum at the neutral. spend

With symmet. e.g.

With no doubt. e.g.

The neutral conductor vibrates the phase voltage.

15І16 Three-phase receiver operation modes.

Distinguish two kinds of z'ednan: at the sirku and at the trikutnik. At your own discretion, when connected to the mirror, the system can be three- and four-way.

Z'ednannya at the zirku

On fig. 6, a three-phase system is induced when the generator phases are connected and driven into the star. Here the darts AA', BB' and CC' are linear darts.

Linear the wire is called, which connects the cob of the phases of the generator winding and the primach. Krapka, at some end of the phases, they grow up at the deep vuzol, they are called neutral(in Fig. 6, N and N' are apparently neutral points of the generator and the bias).

The conductor that connects the neutral points of the generator and the receiver is called neutral(In Fig. 6, the indications are dotted). A three-phase system when connected to the mirror without a neutral drotu is called triprovidny, with a neutral dart - chotiriprovidny.

All quantities that are seen before the phases sound phase change, to the line - linear. As can be seen from the diagram in Fig. 6, when entering into the mirror linear streamsіrіvnі vіdpovіdnim phase strums. For the presence of a neutral dart strum at a neutral dart . Yakscho system phase streams symmetrical then. Since the yakbi symmetry of the strum is guaranteed, then the neutral wire is not needed. How will it be shown far away, neutral wire ensure the improvement of the symmetry of the voltage on the vane with the non-symmetry of the vane itself.

The voltage fluctuations on the dzherel are parallel to the direct line of the EPC, the phase voltages of the generator (div. Fig. 6) go from point A, B and Z to the neutral point N; - phase voltage input.

Linear voltages develop between linear rods. According to another Kirchhoff's law for line voltages, you can write

Significantly, scho zavzhdi - like the sum of the voltage in a closed circuit.

On fig. 7 is a vector diagram for a symmetrical voltage system. How to show її analysis (changing phase voltages will satisfy the sides of equal-femoral tricots with kutas at the main bath, equal to 300), in this direction

Ring out when rozrahunka accepted . Todi for vipadu direct phase drawing , (at reversed phases phase disruptions are called missions). Looking back at the price on the basis of spivvіdnoshen (1) ... (3) can be assigned complexes of line voltages. However, if the stress is symmetrical, the values ​​can be easily assigned directly to the vector diagrams in fig. 7. Directing the speech of the entire coordinate system along the vector (the first cob phase is equal to zero), it is necessary to phase the destruction of the linear stresses exactly along the axis, and the modules are determined to (4). So for linear voltages it is necessary: ;.

Z'ednannya at trikutnik

At the link with it, that there is a significant part of the primaries, that it can be switched on up to three-phase lances, it is asymmetrical, even important in practice, for example, in schemes lighting fixtures, to ensure the independence of the regimes of the robotic phases of the Crimium chotiripide, similar to the power of the mayut and the tripartite lansyugs when the phases of the priymach are connected to the trikutnik. Ale in trikutnik it is possible to connect the phases of the generator (div. Fig. 8).

For a symmetrical EPC system, it is possible

.

In this way, due to the presence of interference in the phases of the generator in the circuit in Fig. 8 strumi add up to zero. However, if you remember the spathes of the cob and the end of the phase, then in the knitwear there will be a strum short hum. Also, for a tricoutnik, it is necessary to strictly trim the order of the phases: the cob of one phase starts with the end of the other.

The scheme for connecting the phases of the generator and the primach into the trikutnik is shown in fig. nine.

It is obvious that when connected to the tricot, the linear voltages are equal to the corresponding phases. According to the first law of Kirchhoff, the connection between linear and phase strumas is marked by spontaneity

Similarly, it is possible to visualize linear streams through phase strums generators.

On fig. 10 shows a vector diagram of a symmetrical system of linear and phase streams. Її analysis shows that the symmetry of the strum

At the end, it is significant that the Crimean days "zirka - zirka" and "tricutnik - tricutnik" in practice are also zastosovuyutsya schemes "zirka - trikutnik" and "tricutnik - zirka".

At the skin gallery of technology, one can always know one’s own in the old hours, call oneself, bring one’s own kind of history to the development of it directly. And few people know what else technically understandable May the old path of formation, zvikannya, and on the cob of its people signified a devilish, often even more significant, term of technical progress. So, for example, among electrical terms, it is often possible to say a little "three-phase voltage", "linear voltage", "permanent" or "changeable voltage" and other nameless names with the word "voltage".

The largest width in electrical engineering was nabuli variable voltage sinusoidal form. The maximum value of the voltage for yogo induction is called the amplitude Ua. For such a voltage, add additional units to the world - the frequency F and the phase ψ. The frequency is determined by the number of bursts in one hour, and the phase - by the time of the destruction of the same burst points. So it has already developed historically, that the term “phase” began to be called the changing voltage, as if it were a part of the system of rich phases - call three. bulli to the devil's reach of electrical engineering and may be so rich in advances that it is simply impossible to pass through. The first of them is the ability to be very simple, in fact, without any zusil, to remove the magnetic field that wraps around - the basic principle of the robotic operation of any kind of electric motor. They differ in phase and line voltage, and their peculiarity lies in the fact that the skin of the phases can be affected by the difference up to two +/- 120 deg. voltages may be used for windings, for some constructive tasks of phases. Skin from windings can be cut and cob H1-K1, H2-K2, H3-K3. In a three-phase system, there are two options for closing the phases - “star” and “trikutnik”.

When the “zirka” is connected, all the ends are connected to one point - “visnovok 0”, and the cobs serve as visible ends for the generator and the input for the attached building powered by it. In such a system, the linear voltage is the same value, which is the same as a pair of other endings H1, H2, H3 and yogo designate Ulin. One more characteristic three-phase mesh- phase voltage. Yogo signify Uf and vimiryuyut between the points of "visibility 0" and be like one of the vihіdnyh kіntsіv K1, K2 and K3. Omitting the details, it should be noted that, appearing from the vector diagrams for a three-phase line, the correlation between voltages Ulin = 33 * Uf. When connecting the “trikutnik”, the ends of the windings are connected along the ring: K1-H1-K2-H2-K3-H3-K1. Skin z'ednannya "kіnets - cob" є vysnovkom, and at tsom linіyna napruga not vіdrіznyаєє in іt phase, tobto. Ulin = Uf. Tsіkavo equalize among yourself constant voltage Udir is the amplitude of the variable voltage Ua, for example, appearing with the same energy, which is seen in the vanishing. For this vipadku Udir = V2 * Ua.

The axis has been accumulating knowledge about the nature and nature of electricity for a decade, and it’s unbelievably simple to understand “voltage” overgrown with controversial terms that expand our ability to use natural phenomena for the needs of people.

In electric lancers buvayut different types voltage. Linear voltage can be measured in a three-phase line, de vono blamed between two phase strands. Most of the yoga riven sygaє 380 volts.

Inspection of line voltage in phase

In order to reveal a three-phase lance, it clearly understood that in the new one there is a voltage between the phase contacts and the phase and zero terminals. Tse vіdbuvaєtsya through those, scho in this scheme vikoristovuєtsya chotiriprovіdny triphazny lansyug. The main indications are voltage and frequency. The voltage, which is due to the lance between two phase wires, is whole, and those that are between phase and zero are phase.

A noteworthy feature of the linear voltage is those that, according to the new one, strum and other parameters of the three-phase stake. In addition, to such a circuit it is possible to connect not only standard three-phase contacts, but also single-phase (certain buttovі attach, accept). Nominal power is 380 volts, at which it can be changed in fallow land in the field or other changes in the local area.

There are many options for such a plant, let's say, the system from neutral to grounding is the most popular. Vaughn is characterized by the fact that it is connected to her to get through for a special scheme:

1. Single-phase inputs are connected to phase darts;
2. Triphasic - up to triphasic vіdpovіdno.

The line voltage can be even wider than the wind of its safety and security of the gaping of the line. Electrical accessories are connected only up to single-phase drota, I imagine wine alone. The development of the system is even simpler, for some they are treated with standard formulas from physics. In order to measure the parameters of the measure, it is enough to speed up with a simple multimeter, in order to measure the characteristics of the phase connection, it is necessary to use a few special attachments (strum sensors, voltmeters and others).

Actual features of the measure:

1. When such wiring is developed, it is not necessary to use professional accessories; all vimiryuvannya carried out by spinning with indicators;
2. When connecting conductors, there is no need to connect zero wire, t. K. Zavdyaki in vіlnіy neutral, rizik zazhennya strum vkraimaliy;
3. Electrical engineering uses such a connection scheme for various electric motors and other outbuildings that require high pressure for work. On the right, in the fact that the vicorous type of tension is the ability to move the KKD to the tretina, which is more crown power, Especially for an asynchronous motor;
4. The scheme is victorious as for snake struma, i for fast;
5. It is necessary to remember that a single-phase connection can be connected to a three-phase line, but not at the same time;
6. Ale, such a lansyug may be so small. AT line service guides are easy to show ushkodzhennya. Tse spryaє pіdvischenіy pozhezhnіy nebezpetsі.

Vidpovidno, the main difference between phases linear tension polygaє in the retail supply of winding wires.

To control this variation of this parameter, a special tool is often used - line stabilizer voltage. Vіn allows you to improve the show on the equal level, with which you can normalize it. One more thing is a pulse stabilizer. Attachment can be connected to the socket, contacts in electrical appliances only.

Z'ednannya

The line and phase voltages are often adjusted to start the generator. Let's look at how they shoot darts from the butt of a three-phase generator. Vin is added up from the first ones secondary windings. Їx can be z'ednati with a star and trikutnik.

Returning the guides to the "trikutnik", the cob of another phase follows the end of the first. Krym tsgogo, to the skin phase conductor, the linear droti of the dzherel are connected. Tse virіvnyuє strum, vihodyachi z why, the phase voltage becomes equal to the linear one. A similar circuit for connecting a transformer and a motor.

This way, it also allows you to secure zero electrical power and constant frequency. Strumi windings zsuvayutsya 120 degrees, why in the wild scheme of the day may look like three okremikh strums, like one can see one zsunuti for 2/3 of the period. Tse spіvvіdnoshennya can change in the fallow land according to the type of building, what is connected, and the characteristics of the fence.

Similarly, you can come three-phase asynchronous motor, a stabilizer or a pidsiluvach at a measure of 220 volts "star". Tsya scheme transfers the connection of the cob of windings to the edge. Just at the entrance, the strum often collapses due to the characteristics of the fence. Output contacts (winding ends) are connected with the cob for additional special jumpers. In this way, the interfacial voltage flows through all active contacts.

AT isolated mesh vikoristovuyutsya different starting capacitors to start the system. Similarly, the adhesives on the windings are connected. Circuit connections are often used for step-down transformers and other motors intended for work in single-phase mesh.

∑ Ik = 0;, how to talk about those that have a lancet knot with a struma strength equal to zero.

І Ohm's law:

I = U/R. Knowing qi laws, you can easily develop a characteristic of a singing contact or a merezhі without any problems.

When the system is decoupled, it may be necessary to calculate the voltage between the phase wire and the neutral one:

I L = I F See what follows linear parameters adjust the phases.

Ale, in singing situations, it is necessary to decompose, which is the most important voltage difference between phase and line conductors.

For which vicory the formula is: Ul \u003d Uf ∙ √3, de:

Ul - linear, Uf - phase. The formula is only valid as I L = I F .

When switched on to a minimum of additional inputs, it is necessary to calculate the phase voltage of the skin switch. The same deputy Uf is submitted to this decree.

When working with industrial installations, you may need a rocket launcher triphasic tension. Vin is prepared according to the formula:

Q \u003d Qa + Qb + Qc

A similar look may make the formula active.

Electric lances of a three-phase snake strum

Triphasic electric strum

Triphasic lanceug is a collection of electric lances, in which there are three sinusoidal e.d.s. the same frequency, which are blown in phase one in a second (φ = 120 pro) and created by a scorching dzherel of energy. The skin part of the rich-phase system, which is characterized by the same strum, is usually called the phase. In this order, the word phase in electrical engineering can have two meanings - kut and part of a rich-phase system (an okremia phase conductor).

main advantages three-phase system : можливість простого отримання кругового магнітного поля, що обертається (це дозволило створити електродвигуни змінного струму), економічність і ефективність (потужність можна передати по трьох фазних проводах без застосування четвертого загального проводу -нейтралі), а також можливість використання двох різних експлуатаційних напруг в одній установці (phase and linear, if you sound to become 220 and 380, obviously).

The history of the appearance of three-phase electric lances connected with the names of M.S. Dolivo-Dobrovolsky St. Petersburg scientist, who was born in 1886, having added that the rich-phase streams of the building create a magnetic field, which turns around, having patented (patented) the design of a three-phase electric motor.

Three-phase strum the simplest system rich-phase streams, building a magnetic field that wraps around. This principle is the basis for robotic three-phase electric motors.

Proponing the design of the electric motor of the snake strum, M.S. Dolivo-Dobrovolsky rozrobiv and all the main elements of the triphasic electric lansyug. Three-phase lance is composed of a three-phase generator, three-phase power lines and three-phase receivers.

As a result of the proponated three-phase system of the electric jet, it became possible to efficiently convert the electric jet to mechanical energy.

Electrical energy triphasic struma take away from synchronous three-phase generators(Fig. 27). Three windings 2 stators are placed 1 between each other in the space at a 120 ° cut. Їx on the cob are known by letters BUT, AT, W, and kіntsi - x, y, z. The rotor of 3 vikonations looks like a constant electromagnet, the magnetic field of such a zbudzhu constant strum I, which flows through the winding 4. The primus rotor wraps around a third-party engine. When wrapping the magnetic field of the rotor, the windings of the stator are successively altered and inducted in them by EPC, destruction (albeit in the hour) between itself at a cut of 120 °.

Three-phase synchronous generator

For a symmetrical EPC system (Fig. 28) it is true

Khvilov and vector diagrams of the EPC symmetrical system

The diagram shows the direct sequence of phase drawing (rewinding the windings by the rotor in order BUT, AT, W). When changing directly, the wrapping of the phases is changed on the turn - BUT, W, AT. Vіd tsogo lie down directly the wrapping of three-phase electric motors.

There are two ways to start the windings (phases) of the generator three-phase primach: “zіrka” and “trikutnik”.

In three-phase stream generators, electrical energy is generated in three identical windings connected to the star circuit. To save on the drots the lines of transmission of electricity from the generator to the spare, it will take only three darts. The wire from the main point of the windings connection is not dragged out, because with the same supports, the tension (with symmetrical navantazhenni) strum at the new road to zero.

Scheme of substitution of a three-phase system obtained by the "star"

According to the first Kirchhoff law, one can write I O = I A + I B + I C.

With the equality of the EPC in the phase windings of the generator, and with the equality of the bearings of the voltage (that is, with the equality of the value of the streams I A, I B, I C) in the representations of the little system, for help vector diagrams it can be shown that the resulting stream I O in the central conductor is equal to zero. In this rank, go out, sho in symmetrical systems (if the cost is the same), the central wire may be daily and the transmission line of the three-phase stream system may consist of more than three wires.

In rozpodіlnyh low-voltage wires, in some є rich single phase dampers, It is impossible to ensure the equal vanishing of the skin phase, so the measures can be broken with chotiripide.

For the security of electrical safety, low-voltage support measures (merezh<1000В), выполнять 4-х проводными с глухо-заземленной нейтралью.

The voltage between the phase wires in the line is usually called linear tension, and the voltage, vimirana between the phase wire (phase) and the central one - phase voltage.

In systems of electrical supply, zokrema in generators and transformers of substations, it is very important to have a star.

For low-voltage lines (with voltage less than 1000V), the main standard line (between phase wires) voltage is 380, with which the phase voltage (between phase wire and central) will become 220 V.

Low-voltage wires are slow-witted wires of different recognition, yakі not ob'yazkovo revitalize three-phase motors. In such fencing for the living of various sspozhivachіv can but vikoristanі raznі phase okremo. As a result, the vanishing of different phases appears to be unequal. In addition, with the help of safety technology, PUE (I will add electrical installations by the rules) are installed, that low-voltage three-phase electrical networks are responsible for power chotiriprovidnimi, with a dead-earthed neutral. For which circuit of a step-down transformer (lower substation) sound like this.

( high voltage

Tobto. central, with "zero" ranks, the conductor on the secondary winding of the three-phase transformer is connected to the grounding outbuilding and brought to the next order with the phase wires.

The skin part of the rich-phase system, which has the same characteristic of the struma, is called phase.
phase voltage- wines between the cob and the end of the phase. Otherwise, it is important to determine how the voltage is between one of the phase wires and the neutral wire.

Line- yak vyznachayut yak interfazne or interfazne - scho vikaє between two wires and the same windings of different phases. The indicator of the phase voltage should be approximately 58% of the linear parameters. In this order, for the normal minds of exploitation, the indications of linear however and shift phases by 1.73 times. In a three-phase line, the voltage, as a rule, is estimated according to the data of the line voltage. For three-phase lines that enter the substations, a line voltage of 380 volts is installed. Tse vіdpovіdaє phase 220 volts.

So, strums, like in the skin phase, are called phasic and mentally designate IA, IB, IC, or else Iph. Strumi at the heels of the venture are called linear. This value is determined by the value of the phase voltage, the type of tension. In the case of a daily active voltage stream, they are identical to the phase voltages, and in the case of an inductive or an omnipotent voltage stream, they can either change or differ in voltage.

In traditional electrical installations, there are 2 methods of connection:

Trikutnik;

When connecting the wires of the circuit with a tricot, one winding is connected to the cob, otherwise. exit a closed loop. Up to the skin knot of the scheme, the balance is reached - the sum of the input streams is equal to the sum of the output ones. With such a connection to the symmetrical vanishing, the spiving is victorious:

When connecting the wires of the elements in the circuit, all the terminations of the phase windings are connected to one node 0. Looking at those that the phases of the generator are connected sequentially with the phases of the electrical receivers (navantage), then the linear jets after the value of the phases are improved:

21. Z'ednannya spozhivachiv three-phase struma for the scheme "zirka". Symmetrical and non-symmetrical modes.

When connecting the phases of the winding of the generator (or transformer) X, Yі Z go to one sleeping point N, which is called a neutral point (above a neutral point) (Fig. 3.6). End phases of priming ( Z a, Zb, Z c) also go to one point n. Such a day is called a day of zirka.

Provide A−a, B−bі C−c, which start the cob of the phases of the generator and the primach, are called linear, N−n, what is the starting point N generator with dot n priymacha, - neutral.

A triphasic lansyug with a neutral droth will be chotiric, without a neutral droth it will be tripartite.