JPH0588523B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a single-phase transformer in which a tap winding and an excitation winding are wound around the side legs of an iron core.

[Conventional technology]

As a single-phase transformer in which a tap winding and an excitation winding are wound around the side legs of an iron core, a structure as shown in, for example, Japanese Unexamined Patent Publication No. 56-48114 has been proposed. This will be explained using a diagram.

FIG. 3 is a winding layout diagram of a conventional single-phase transformer. In the figure, 1A and 1B are high voltage windings, 2A and 2B are medium voltage windings, and 3 is a low voltage winding. These windings are wound around the main legs 4A, 4B of the iron core in the order shown. 5 is an excitation winding, and 6 is a tap winding, and these two windings are wound around the side leg 4C of the iron core in the order shown. The two high voltage windings 1A, 1B are connected in parallel with each other, and the two medium voltage windings 2A, 2B are connected in series with each other. Further, the low voltage winding 3 and the excitation winding 5 are connected in parallel with each other.

In a single-phase transformer with such a configuration, the impedance between the medium-voltage winding and the low-voltage winding is determined by the impedance between the high-voltage winding and the medium-voltage winding of the main leg 4A, since the medium-voltage winding is connected in series on the main legs 4A and 4B. This has the advantage that the impedance between the lines becomes larger due to the addition of impedance. Another advantage is that it is possible to suppress the range of change in impedance between the high-voltage winding and the low-voltage winding due to tap switching. This is shown in FIG.

FIG. 4 is a magnetic flux density distribution diagram corresponding to the configuration shown in FIG. 3. In the figure, curves A, B, and C indicate the magnetic flux densities in the main legs 4A, 4B, and the side legs 4C, respectively. B ₁ , B ₂ , and B ₃ are the magnetic flux densities when the tap positions are the highest tap, middle tap, and lowest tap, respectively, and C ₁ and C ₃ are the magnetic flux densities when the tap positions are the highest tap and the lowest tap, respectively. be. In the main landing gear 4A, the medium voltage winding current is constant, so the magnetic flux density does not change depending on the tap position and the impedance is also constant. On the other hand, in the main leg 4B, since only the main leg 4B shares the change in the high voltage winding current depending on the tap position, the magnetic flux density changes considerably. However, since the impedance of the main landing gear 4A is constant, the range of change in impedance between the high-voltage winding and the medium-voltage winding can be reduced overall.

[Problem that the invention seeks to solve]

In the conventional single-phase transformer described above, although the change in impedance in the main leg can be suppressed, the change in impedance as a whole is quite large. Not only the conventional single-phase transformer described above, but also other single-phase transformers such as single-phase single-turn transformers, single-phase transformers with excitation windings and tap windings wound around the side legs. In transformers, it has been difficult to further reduce the change in impedance of the entire transformer caused by switching the tap position.

An object of the present invention is to provide a single-phase transformer that can reduce the change in impedance of the transformer when the tap position is switched, compared to conventional transformers.

[Means for solving problems]

In order to achieve the above object, the present invention provides a single-phase transformer equipped with a tap winding wound around a side leg and an excitation winding, in which the excitation winding is divided into a first excitation winding unit and a second excitation winding unit. The first excitation winding unit is wound on the inside of the side leg, the tap winding is wound on the outside of the first excitation winding unit, and the second excitation winding is wound on the outside of the first excitation winding unit. The device is characterized in that the first excitation winding unit and the second excitation winding unit are connected in series.

[Effect]

By dividing the excitation winding into two and winding each winding around the side leg with a tap winding sandwiched between these divided excitation windings, the magnetic flux density in the side leg is reduced, that is, The impedance at the side leg is reduced, and as a result, changes in the impedance of the transformer when switching the tap position are suppressed.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a winding arrangement diagram of a single-phase single-winding transformer according to an embodiment of the present invention. In the figure, 10 is an iron core, 11 is a main leg of the iron core 10, and 12 is a side leg of the iron core 10.
13 is a tertiary winding, 14 is a shunt winding, and 15 is a series winding, and each of these windings is connected to the main landing gear 11 in turn.
is wrapped in. Reference numeral 16a denotes one of the two divided excitation windings, and hereinafter this will be referred to as the first excitation winding. 16b is the other winding of the divided excitation windings, and is referred to as a second excitation winding. 17 is a tap winding. Each of these windings is
With the first excitation winding 16a inside, the tap winding 17
It is wound around the side leg 12 with the excitation winding 16b in the middle and the second excitation winding 16b on the outside. That is, the tap winding 17 is sandwiched between two divided excitation windings 16a and 16b.

First excitation winding 16a and second excitation winding 16b
are connected to each other in series, a shunt winding 14 is connected in parallel to this series circuit, and a series winding 15 is connected to this parallel circuit.

In the single-phase single-winding transformer configured in this way, by connecting the shunt winding 14 in parallel with each excitation winding 16a, 16b, when the tap position is switched, the shunt winding 14 and the series winding Although the current distribution within the wire 15 is kept almost unchanged, in this embodiment, the excitation winding is further divided into a first excitation winding 16a and a second excitation winding 16b,
By sandwiching the tap winding between these divided windings, changes in the impedance of the transformer due to switching of the tap position can be suppressed.

FIGS. 2a and 2b are a winding arrangement diagram of the side leg shown in FIG. 1, and a characteristic diagram of the interlinkage magnetic flux density at the corresponding position, respectively. In FIG. 2a, the same parts as those shown in FIG. 1 are given the same reference numerals. or,
In Figure 2b, C' is the magnetic flux density at the highest voltage tap position, C'' is the magnetic flux density at the center tap position, and C is the magnetic flux density at the lowest voltage tap position. N _E1 : Number of turns of the first excitation winding 16a N _E2 : Number of turns of the second excitation winding 16b D _E1 : Winding width (cm) of the first excitation winding 16a D _G1 : First excitation winding 16a and tap winding 17
Dimensions of gap _G1 between (cm) D _T : Winding width of tap winding 17 (cm) D _G2 : Tap winding 17 and second excitation winding 16b
Dimensions of the gap G ₂ (cm) D _E2 : Winding width of the second excitation winding 16b (cm) R _E1 : Average radius of the first excitation winding 16a (cm) R _G1 : Gap G ₁ R _T : Average radius of tap winding 17 (cm) R _G2 : Average radius of gap G ₂ (cm) R _E2 : Average radius of second excitation winding 16b (cm) I: Each Current flowing through the excitation windings 16a, 16b (A) f: Frequency of current I (Hz) h: Height of each winding 16a, 16b, 17 (cm) P: Standard capacity of transformer (VA) Then, tap The winding 17 and each excitation winding 16a,
16b, the impedance % V _Z1 is roughly expressed by the following equation.

%V _Z1 = 7.9fN _E1 ²・I ²・Δ ₁ /P×10 ^-6 (%)
...(1) However, Δ ₁ is Δ ₁ =D _E1 /3・2πR _E1 /h +D _G1・2πR _G1 /h+{
1−N _E2 /N _E1 + (N _E2 /N _E1 ) ² }・D _T /3・2πR _T /h
+(N _E2 /N _E1 ) ²・{D _G2・2πR _G2 /h+D _E2 /3・2
πR _E2 /h}...(2) Next, for comparison, let us consider the conventional winding arrangement in which the excitation winding is not divided, as shown in FIG. In this case, N _E : Number of turns of excitation winding D _E : Width of excitation winding D _G : Dimensions of gap between excitation winding and tap winding D _T : Width of tap winding R _E : Excitation from side leg Distance to the center of the winding R _G : Distance from the side leg to the center of both winding gaps R _T : Distance from the side leg to the center of the tap winding, then the impedance between the tap winding and the excitation winding %V _Z2 is roughly expressed by the following formula.

%V _Z2 = 7.9fN _E ²・I ²・Δ ₂ /P×10 ^-6 (%
)...(3) However, Δ ₂ is Δ ₂ = D _E /3・2πD _E /h+D _G・2πR _G /h
+D _T /3・2πR _T /h...(4) Now, if we design a single-phase autotransformer with the same specifications, comparing equations (1) and (3), we find that the values f, I , P are the same, and the number of turns N _E is N _E =N _E1 +N _E2 .
Also, there is a slight difference between the value Δ ₁ and the value Δ ₂ depending on the insulation dimensions between the windings, but as an example, the value Δ ₁ is the value Δ ₂
It is about 1.6 times that of If the numbers of turns N _E1 and N _E2 are equal, the ratio of both impedances is as follows.

%V _Z1 /%V _Z2 = 0.4 ...(5) That is, the impedance of the side leg 12 is higher than the conventional configuration in which the excitation winding is not divided into two, as in the present embodiment, where the excitation winding is divided into two. In a configuration where the tap winding is sandwiched between two windings, the reduction will be approximately 40%. In this way, since the absolute value of the impedance becomes small, naturally the change in impedance when switching the tap position also becomes small.

〔Effect of the invention〕

As described above, in the present invention, the excitation winding is
Since the tap winding is sandwiched between these divided excitation windings, changes in the impedance of the transformer caused by switching the tap position can be
It can be made even smaller than the conventional one.

[Brief explanation of the drawing]

Fig. 1 is a winding arrangement diagram of a single-phase single-winding transformer according to an embodiment of the present invention, and Figs. 2 a and b are winding arrangement diagrams of the side legs shown in Fig. 1 and characteristic diagrams of interlinkage magnetic flux density. , 3rd
The figure is a winding arrangement diagram of a conventional single-phase transformer, and FIG. 4 is a characteristic diagram of magnetic flux density of the single-phase transformer shown in FIG. 3. 10... Iron core, 12... Side leg, 16a... First
Excitation winding, 16b...Second excitation winding, 17...
...Tap winding.

Claims (1)

[Claims] 1. In a single-phase transformer equipped with a tap winding and an excitation winding wound around a side leg, the excitation winding is divided into a first excitation winding unit and a second excitation winding unit,
The first excitation winding unit, the tap winding, and the second excitation winding unit are wound around the side leg in order from the inside thereof, and the first excitation winding unit and the second excitation winding unit are wound on the side leg in order from the inside thereof. A single-phase transformer characterized by connecting winding units in series.