Three-phase electric lances. The Great Encyclopedia of Oil and Gas

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operating voltage single-phase mesh dorivnyuє 220 volts. For three-phase mesh this indicator is 380 volts. It is obvious that another value is richer for hoarding in Moscow apartments.

To this, special respect for the varto is given by electrical safety. At the present time, it’s rare for the masters to reach the norms of zahistu themselves with that electric power. So, ELV systems are far from being installed near a private skin booth, but they are considered the prerogative of technically “pidkovykh” Vlasniks. The electrical panels are repaired hourly, old parts of the wiring are replaced. An unfortunate fall can be fatal, especially if it is a high-voltage lance.

Vіdpovіdno to norms fire safety, triphasic introduction to be brought up to a higher category of unsafety, so like a strum at a voltage of 380 volts, it is richly high.

Before the shortfalls, you can see:

The need for additional permits for connecting a three-phase stream to an energy-saving company. For an hour, if you allow them to take away, you can take a lot of time, and it’s still not a fact that you take it off.

Promoted by a strum attack. Like wooden houses, or wiring, otherwise you can drive, you can install an additional three-pole automatic machine in front of the house itself.

Entry shield dimensions. For the lords of the great zamіsky budinki it is not a problem, resht varto take this factor to the point of respect.

For a three-phase shield, it is necessary to install intermediate overvoltages. Tsej zahіd bude not navit navіt for single-phase merezhі. An individual working zero can break, but it will threaten with an overvoltage at least in one of the phases.

Benefits of a three-phase introduction:

He changed the focus between phases, unique in his “phase imbalance”.

At the railing, you can turn on the tight three-phase electrical receivers. Tsya the lead is the head one, tied with the others. Before hard-pressing people energy is seen in the boilers, different electrical installations of the blast jet.

For a three-phase line, the rating of the inlet shield and cable cut has been reduced.

Dali, in order to take the necessary permit documents, and to acquire loyalty to the company - you can maximize the maximum allowable energy savings. This is especially necessary for the masters of the great cottages or the great castle houses.

In practice, the demand for a three-phase lancet increases with the increase in the area of \u200b\u200bthe dwelling. Exactly - 100 and more square meters. Such a dwelling has a richly calm struma, and a triphasic lancet allows you to competently expand the vanity.

As soon as a scorching system has been installed, it is necessary to carry out a test, as if to check the vice in the scorch systems. Zavdyaki such a test can be recognized that the system is airtight and that it is not enough, that it is necessary to correct it before putting it into operation.

Three-phase lances are known as low-phase electrical systems, in which there are sinusoidal EPCs of the same frequency, phase failures are visible one to one per sing cut. The most rational and promising was the three-phase system, developed by the Russian scientist M.O. Dolivo-Dobrovolsky. In the development of three-phase systems, a great contribution was also made by N. Tesla, F. Haselwander, M. Despres, C. Bradley and others.

At this time, in the energy system of the three-phase systems, the largest expansion was found, which is due to the low transcendence of the three-phase lances in front of the single-phase ones, the most important of them:

The economy of transmission of electricity is great, because replacement of six wires (about a single-phase system) here you need only three darts;

The most economical and economical three-phase asynchronous motor with short-circuited rotor and three-phase transformer;

Possibility of taming the magnetic field, which wraps up, on which the robot of synchronous, asynchronous and linear motors is based, as well as a number of other electrical appliances.

The simplest three-phase generator, shown in Figure 4.1a, is three single-phase generators located in one building. The generator stator is an empty cylinder on the inner surface of a groove in which there are three identical windings (phases). Qi windings are rotated in such a way that their magnetic axes will be pushed into each other by 120 °. On fig. 4.1a the skin phase of the stator is shown mentally as a single turn. Cobs of windings are considered to be great letters A, B, C, And kіntsі - in pіdpovіdno great X, U, Z. Rotor є є stіynym elektromagnіtom with wrapping like, in non-robust windings of the stator sinusoidal EPC is induced (Fig. 4.2.b).

4.1. a) generator circuit simplified b) EPC clock diagrams c) EPC phase vector diagram

Main spontaneity

When the winding is turned on, the rotor is excited to the point fast strumu a strum flows along it, which creates a permanent magnetic flow. When wrapping the rotor with the primary motor, the current flow is due to the law of electromagnetic induction induction in the stator windings A, B, C three similar in magnitude and frequency sinusoidal EPCs, broken in phase by 120° (Fig. 4.1b).

Yakscho EPC phase BUT take it for granted, tobto. go from the speech line of the complex plane (Fig. 4.1c), then the EPC of the other windings (phases) of the generator can be recorded at a glance:

;

Such a three-phase EPC system is called symmetrical system.

Complexes exploding values phase EPC at the display form, sign up at the viewer:

; ; .

Significantly multiplier

through a and we will call triphasic lanceg operator.

Complexes of the developing values of the EPC phases can be recorded and

;

;

Come on todi ,

The algebraic sum of the mittievs of the EPC value (voltage, strum) of a symmetrical system at any moment is closer to zero (Fig. 4.1.b and 4.1.c):

or in complex form(Fig. 4.1. c)

or ,

The sequence of passing the EPC through the same value (for example, through the zero value) is called phase order. The EPC system has been reviewed (Fig. 4.1.b, c) straight phase order ( ABC), at the same voltage (EPS) zsnutі 120 °. How to remember the two phases of the missions ( DIA), then we take about fraternal the order of the phases (suw phases 240 °). If the EPC of all three phases pass through zero at the same time, maybe zero the order of the phases (360 ° phases). The order of the passage of the phases determines the nature (directly rush) of the magnetic flux i, also, injects the mode of operation of the asynchronous motor.

Let's take a look at the methods of combining the elements of triphasic lances.

Іsnuyut different ways windings of the three-phase generator and windings. Of these, the main ones are “zirka” and “trikutnik”. The “star” is called such a half, if the cob of three phases (X, Y, Z) is combined into one (zero) point, and the ends of the phases (A, B, C) are joined to linear darts (Fig. 4.2. a).

In triphasic lancers, they are distinguished phaseі linear the magnitude of the voltage and strum.

Check that the generator is starting up from the vanishings, they are called line wires, but the streams that flow through them linear streams ( , , ). (Fig.4.2. a)

tension between line wires called linear (interphase) voltages (

,

,

- on the dzhereli that

,

, - on the vantage). (Fig.4.2. a)

strums, which flow through the phases of the generator or the receiver, are called phase struma( , , ), and the stresses between the cob and the end of the phases are called phase voltage (

,

,

- on the generator , , - on the vantage).

When z'ednanny with a star phase strum dorіvnyuє vіdpovіdny line strum, because phase and line included in series:

Virazimo linear stress

,

,

through phases

,

,

(Fig.4.2b).

For which we can write equal to another Kirchhoff's law for three circuits, made with one of the linear voltages and two phase voltages, and from them we can see the linear voltages (Fig. 4.2. b), we take:

4.2. a) Scheme for setting up the Zirka generator; b) vector diagram of phase and line voltages.

1. Theoretical part

1.1. Triphasic lanceuges. Galuzy zastosuvannya. Gidnosti and nedolіki. Uvіmknennya schemes. Modes …………….................................................. ................................................3

1.2. Three-phase transformers.……………………………19

1.3. Electric vimіryuvachі strumu i prugi strumu ……………………………………..………………………………26

2. Practical part

2.1. Rozrahunok for transformers.…………………………………..37

2.2. Rozrahunok for asynchronous motors……………………….42

Triphasic lances. Galuzy zastosuvannya. Gidnosti and nedolіki. Uvіmknennya schemes. modes.

Three-phase lances are known as a phase of rich-phase electrical systems, which are a collection of electrical lances, in which EPCs have the same frequency, failures in phase are visible one to one per song. Significantly, scho zvichay tsі EPC, we are ahead of the power of energy, sinusoidal. However, in today's electromechanical systems, where for the control of high-speed motors, high-frequency frequencies are changed, the voltage system is not sinusoidal. The skin part of the rich-phase system, which is characterized by the same strum, is called phase tobto. phase - tse lіlyanka lansyug, scho vіdnositsya to vіdpovіdnoї winding of the generator or transformer, lines and navantage.

In this order, understanding the "phase" in electrical engineering can have two different meanings:

· Phase yak argument sinusoidally changing values;

yak phase warehouse part rich-phase electrical system.

The development of rich-phase systems was zoomed in historically. Studies in this region were viklikanі vomogami vyrobnitstv, scho develop, and successes in the development of rich-phase systems have spliced evidence from the physics of electrical and magnetic phenomena.

The most important reason for the expansion of rich-phase electrical systems was the appearance of a magnetic field that turns around (G. Ferraris and N. Tesla, 1888). The first electric motors were two-phase, but they had low operating characteristics. The most rational and promising was the three-phase system, the main advantages of which will be considered further. A great contribution to the development of three-phase systems was made by the well-known Russian teaching-electrical engineer M.O.

Dzherelom three-phase voltageє three-phase generator, on the stator of which (div. Fig. 1) is placed three-phase winding. The phases of the coil windings are roztashovuyutsya in such a rank, so that their magnetic axes will be put out of the open space one at a time for eating. radium. On fig. 1 skin phase of the stator is mentally shown as one turn. Cobs of windings are usually denoted by great letters A, B, C, and kіntsi - apparently by great letters x, y, z. EPC in the non-robust stator windings are induced as a result of a turn of their turns by a magnetic field, which creates a winding winding excitation of the rotor, which wraps around (in Fig. 1, the rotor is mentally imaged at a permanent magnet, which turns into practice at a low pressure). When the rotor is wrapped with equal swirl in the windings of the stator phases, sinusoidal EPCs are induced, which periodically change, however, the same frequency and amplitude, and then they are blown by the space sounding one in one in phase per rad. (Div. small 2).

Triphasic systems in Denmark have gained the greatest width. On the triphasic strum Pratsyuyut mustache large power plants and slow, which is due to the low advantage of three-phase lances in front of single-phase ones, the most important of them:

Economy of transmission of electric power is great;

The most economical, which satisfies the power of the industrial electric drive is an asynchronous motor with a short-circuited rotor;

Possibility of otrimannya for the help of non-robust windings of the magnetic field, what turns around, what is the basis of the synchronous robot asynchronous motors, as well as a number of other electrical appliances;

Vrivnovazhenist of symmetrical three-phase systems.

To see the most important dominance three-phase system, as will be brought further, let us understand the symmetry of the rich-phase system.

The EPC system (voltage, current flow) is called symmetrical as it is, there are m equals for the EPC vector module (voltage, streaks), failures in phase one at least one per equal cut. Zocrema, a vector diagram for the symmetrical EPC system, which shows a three-phase sinusoid system in fig. 2 is shown in fig. 3.


Fig.3	Fig.4

Z non-symmetric systems The most practical interest is a two-phase system with 90-degree phase failure (div. Fig. 4). All symmetrical tri- and m-phase (m>3) systems, as well as two-phase systems investment. Tse means what you want in the next phases mitteva tightness pulsing (div. fig. 5, a), changing not only the value for an hour of one period, but in a deep depression and sign, the total tension of all phases is filled with a constant value for the duration of the last period of the sinusoidal EPC (div. fig. 5, b).

Timeliness is more important than practical value. Yakby sumarna mitteva the tension throbbed, then on the shaft between the turbine and the generator there was a pulsating moment. Such a change in mechanical innovation would be shkily used on power generating installations, a short term for service. Qi w mirkuvannya can be seen and up to rich-phase electric motors.

If the symmetry is destroyed (Tesla's two-phase system, due to its specificity, is not accepted to respect), then the vrіvnovazhenіst is also destroyed. That's why it's hard to follow him in the energy sector, so that the generator's voltage becomes symmetrical.

Lecture triphasic electric lancers

The constellation of electric lances, which have sinusoidal EPCs of the same frequency and amplitude, disruption of one in phase and creation in one dzherel of electrical energy, is called a rich-phase system of electrical lances. Skin s single-phase lances, which enters the rich-phase system, is accepted as the phase.

The largest expansion in the current energy sector was formed by the three-phase lancets, which are rimmed by the high-phase systems of the snake struma.

Under a three-phase symmetrical EPC system to understand the sequence of three sinusoidal EPCs of the same frequency and amplitude, broken in phase at a cut of 120 º. I creation in one dzherel of electrical energy ().

To reinstate three EPCs, they are designated with a senior rank. If you recognize one of the EPCs through EA, then if you look at it at a cut of 120 º, EPC is denoted by EB, and if you see it at 120 º - EC.

Sequence of EPC passage through the same value (for example, through zero) sound. sequence of phases.

The triphasic lancet is composed of three main parts:

1) Three-phase generator - in which mechanical energy is converted into electrical energy three-phase system EPC;

2) Power lines(Where do you enter as the lines themselves, and and transfer. Substations with the necessary settings);

3) accepting energy, which can be both three-phase and single-phase.

Perevagi triphaznyh lanceugs.

1. Ease of removing the magnetic field that wraps around, stuck in three-phase asynchronous power supplies. motors (the main sources of electricity) (about 70%).

3. Less waste of energy transfer time.

4. Persistence of strain for the singing minds.

The generator is a synchronous machine with three symmetrically wound windings on the stator (Fig. 5.2)

Ways to depict 3 phases. sym. syst. EPC.

3 phase symmetrical system EPC may be shown Graphs, trigonometric. functions, and functions of the complex snake.

At 3 phases. sym. syst. EPC. fair rіv-in

2. Like a sinusoid. EPC of phase A is taken as the output phase equal to zero, then the mittve of the EPC value can be shown, then the mittve of the EPC value can be shown trigonometric functions

;

3. vector.

І in which direction the geometrical sum of the EPC vectors reaches zero.

Direct sequence black. ABC phases.

4. Image of the EPC function of a complex snake.

; ;

Ways to connect the phases of a three-phase generator.

They took away roses every day. z'ednannya phases "star" and "trikutnik"

Vector diagrams.

For smart position. Directions The phase voltages are taken directly from the cob to the end of the phases of the windings, and the Line voltages from the forward.

Similar to another Kirchhoff law