Electrical engineering with a star. Z'ednannya in the sky without a zero dart
Like the ends of all the phases of the generator, they are connected to the deep vuzol, and the cob of phases is connected to the heads, which makes the three-promenu star of the supports, the three-phase lansyug, the star of the star. With this, three darts turn into one, the ranks are zero or neutral. Triphasic lance, with a star, is shown in fig. 7.1.
Conductor, scho to go to the dzherel to navantage is called linear droti, provid, scho neutral points of dzherel N and receiver N "is called neutral (zero) wire. phases or between line and neutral wires are called phase voltage. Strumas in the phases of the primach or dzherel are called phase strumas, strumas in linear darts are called linear strumas. So, as linear darts are connected sequentially with the phases of the dzherel and the primach, the linear streams at the same time as the phase streams.
Il \u003d If.
Z N - opir neutral drotu.
Linear voltages are equal to geometric differences in the main phase voltages
On fig. 6.2 shows a vector diagram of the phase and line voltages of a symmetrical dzherel.
Rice. 6.2
With a symmetrical EPC system, the line voltage is greater for the phase by √3 times.
Ul = √3 Uf
6.3. Z'ednannya at the trikutnik. Scheme, by design
As soon as the skin phase of the winding of the generator ends with an ear of the offensive phase, the tricutnik is closed. Three linear rods are connected to the connecting points of the windings, which lead to the beginning. On the Rice. 6.3 a triphasic lancet is depicted, with a tricutnik. As can be seen from Fig. 6.3, in a three-phase lance, connected by a tricot, the phases and line voltages are the same.
Ul \u003d Uf
I A , I B , I C - linear streams;
I ab, I bc, I ca - phase struma.
Linear and phasic streams of vanity are related to each other by Kirchhoff's first law for knots a, b, c.
Rice. 6.3
Linear strum is more expensive geometric retail phase streams. On fig. 7.4 shows a vector diagram of a three-phase lancet, connected with a tricot with a symmetrical entanglement. Navantage is symmetrical, as the phase supports are the same. The vectors of the phase streams run directly from the vectors of the current phase voltages, the voltage spikes are formed from the active supports.
Rice. 6.4
W vector diagrams you can see what
,
Il \u003d √3 If-with symmetrical vanishing.
Triphasic lancers, with a starry, naboule of a larger width, lower triphasic lancers, with a tricot. Tse is explained by Tim, scho, in Perche, c 
epi, zadnanoї zirkoy, you can take two voltages: linear and phase. In another way, as the phases of the winding of an electric machine, connected by a tricotnik, are known in different minds, in the windings there are additional streams that they are navantazhuyut. Such streams are present at the phases of an electric machine, connected behind the "star" circuit. Therefore, it is practical to uniquely close the windings of three-phase electrical machines in trikutnik.
I want to know it easier for formulas (6.3) and (6.4). According to the phase voltages, it is easy to determine the strumi.
The next step is to specify what the linear voltages should be set to sound only after the value ( fiery meaning). To determine the complex values in this direction, the tricot of the linear voltage should be spread on the complex plane in such a way that one vector of directions along the axis day numbers. After the first analysis of the geometry of the topographic vector diagrams, the cob phases of the other linear stresses are determined.
On the topographic diagram, the position of the neutral point 0 may be assigned.
1. Shaving the phase of the face without zero dart(Fig. 6.30, a). At times, the position of the zero point is not determined by the generator;
Shards, then. In fact, the supports and are wrapped around by one strum, but it’s possible to assign positive directions directly to the importance that the strums are located at the opposite phase. The sum is equal to zero (diagram in Fig. 6.30, b). With whom
.
 but) | b) |
 in) |
|
| Rice. 6.30 |
The voltage vector diagram (Fig. 6.30, c) will follow the given line voltages and the specified phase conductivities. Let it go, what else 
, then the stresses on the phases of the input are:
.
Tension on open clamps
2. Look at the other butt, if the shave is at the phase C(Fig. 6.31, a), and the phase transition has a smaller character ( active opir i єmnіst), moreover r=xC= 1 ohm The line voltage of the symmetrical dzherel B. It is necessary to determine the phase voltage , , .
 but) |  b) |
| Rice. 6.31 |
It is accepted that the vector of rectifications along the axis of real numbers, so In addition 
IN, 
B. Conductivity of wires , , . Appropriate to formulas (6.6) and (6.7), the phase voltages are determined by virazes:
The stresses can be determined from the analysis of the geometry of the vector topographic stress diagrams. Razrahuvshi strumi on the cob
pobuduєmo from the point 0 "on the vector plane:
Let's wait for vectors of linear voltages. The voltage is shown as a vector, drawing from the point 0 "to the point C. The first argument is equal to 90°, and the modulus is the sum of the heights of the upper and lower tricouts.
3. Short chime have zirtsі without zero drotu. On the back of the hand we can see the lanceg in fig. 6.32 that is significant as the strumi changes symmetrical stars without zero droto with short-circuited phase B 0" , as in symmetrical mode strum dorivnyuvav I.
On the voltage diagram (Fig. 6.33 a), point 0 "shifts to a point B, The position is simply given by a symmetrical dzherel. Kut between the phase voltage and the door is 60º. Shards of cuti zsuvu in phases are the same, between strumas they take the same cut 60º (Fig. 6.33, b). When folding strums according to the first law of Kirchhoff
In an asymmetric circuit (Fig. 6.34, a), the voltage diagram (Fig. 6.34 b) is saved, but the spiving of the stream changes (Fig. 6.34, c), with which the stream of short-circuiting is equal to the magnitude of the stream of two non-shocked phases.
Z'ednannya trikutnik
It is necessary to respect that the windings of the generators are not connected to the tricotnik, because with such a connection, the unbalance of the phase eds is insignificant. produce before the appearance of significant strums, which is not permissible beyond the minds of exploitation.
Yak dzherela, phase f.f.s. such connections to a tricutnik, it is possible to vicorate a three-phase transformer with secondary winding, z'ednany at trikutnik. Transformers in triphasic lancers can mothers are the same, but different schemes for connecting magnetically coupled windings.
Different payment schemes allow you to please each other three-phase systems z raznimi for the value of abo (i) elastic phase.
Triphasic attraction, arrived to the border, maybe put in a trikutnik. At asymmetric modes robotic primach, z'єdnagogo in tricoutnik, phasic and vidpovіdno іnіynіnі strums appear errіvny, however, in case of any non-symmetry, the sum of complex values of іnіyіnіyіnі striаv is equal to zero:
.
Head of the rozrahunka of the lansyug at asymmetric ambition, z'ednanoї in trikutnik, it's easy to hang, shards behind the driven line voltages you can know the phase of the jet. According to the first law of Kirchhoff, linear streams are appointed. Let's look at the low okremih vipadkіv.
1. Shaving the phase at the trikutnik (Fig. 6.35, a). The topographic diagram of the stresses at this point (Fig. 6.35 b) is not deformed. The structure of the vector diagrams of the stream is the same as in the symmetrical
 but) |  b) |
 in) |  G) |
| Fig.6.35 |
modes, the form is deformed by diagrams. One point will be the star of the phase streams (Fig. 6.35, c and d). Shards can be considered that the end and the beginning of this vector are located at one point, and at the same point, where all phases of the stream begin. The ends of the vectors in these phase streams are flashed by linear streams, and directly the orientation of any of them (as in the symmetrical mode). Strum of straightening in all options (Fig. 6.35, c and d) from the end of the vector to the end of the vector , Strum - from the end of the vector to the point of divergence of the phase streams i , the spikes at this point begin and end the zero vector of the struma. Z tsієї point pochinaєtsya vector , directing at the end of the vector . Complexes of strums and are in protiphase, although the strum is practically the same. This is the result of a specific selection of direct strums in tricot. The streams are physically the same (div. scheme in Fig. 6.35, a) and are depicted by the same vectors, the spikes are smartly positively directed to the streams.
On fig. 6.35, accepted 
the same value
.
The blunt cut of the tricot tree is 120 °, later,.
On fig. 6.35 g if
May be the correct tricutnik of strums, all strums for the size of the streak.
2. Shaving the linear dart in a tricot (Fig. 6.36, a). In times of expansion, the point of the topographic voltage stress diagrams is not indicated by the generator. Therefore, the voltage diagrams and strums will follow at the same time. The order of inspiration vectors is shown in fig. 6.36 b. Three of the same points will be vectors and streams. Vectors are oriented behind them and it is assigned to the topographic diagram of the position of points a, A,b≡Bі c. Dot, mottled C to be at the top of the correct trikutnik ABC, vectors, і to establish a system of direct passage of phases. The strum is oriented according to the vector, which starts in the same point, which and two others phase struma. Mayuchi zіrku phase strums, about її kіntsіv zamikayutsya linear streams, i . The shards of these vectors are located at one point, the stream of the broken line on the diagram reaches zero.
 but) |  b) |
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 | in) | |
 G) |
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| Rice. 6.36 | ||
On fig. 6.36, this order is prompted by diagrams for active quest. There is a speck here c lie in the middle of the vector, so 
. The value of the height of the correct tricot of the generator voltage. The size of the vdvichі is less than the struma, the linear struma becomes. One and the same strum of representations on the scheme of the lancet with two smart positive lines of the strum, as seen on the diagram in fig. 6.36, two vectors (i) are shown in the new one, as they are in antiphase.
 but) |  b) |
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 in) |  | G) | |
| Rice. 6.37 | |||
On fig. 6.37 g
3. Short-circuit phase in the line wire that is connected. The position of all points of the circuit (Fig. 6.37, a) on the topographic diagram is set by the generator voltage (Fig. 6.37, b). Moreover, the potential of the point C,c,a however.
The strum diagram (Fig. 6.37, c) will be based on the pre-trial rules, depending on the strum, , as they can be re-insurance and orientation for different voltages. Vectors and will be from one point, and strum - so, so that it ends with the end of the vector. The vector cob is to designate the position of the vector terminus, and the cob of its vector is moved from the vector cob i. Then the structure is supplemented with diagrams by daily streams and . The values of i can be determined from the geometry diagrams.
On fig. 6.37, prompted a strum diagram for 
. Here , 
. The value may be covered by the cosinus theorem, or it can be determined by the length of the vector by the diagrams at the appropriate scale.
Let's look at the signs of mixed ambition. Come on 
, , at 
. 3 diagrams in fig. 6.37 g, prompted in the same order, next to the flower of the crowns: the vector , which is between the vectors and , is equal to zero. All other strums, krim strums, for the same size:
.
A, a
BUT.
Behind the first law of Kirchhoff we know the strumi:
BUT.
BUT;
BUT.
For the first law of Kirchhoff
