JPH097847A - Pfc transformer - Google Patents

Abstract

PURPOSE: To reduce the filling amount of a cooling medium in a PFC transformer than that of a cooling medium in a present oil-filled transformer by a method wherein one partition wall is formed in an insulator, the section of the insulator in the thickness direction is formed into a rectangle and the interior of the insulator is made solid. CONSTITUTION: One insulator 8, which is used as a partition wall, is installed in the middle between an inside winding 2 and an outside winding 1. A gap formed between the wiring 2 and the surface on one side of the surfaces of the insulator 8 and a gap formed between the winding 1 and the other surface of the insulator 8 are respectively formed as a liquid level, on which a perfuloro carbonid solution flows. The windings 2 and 1 are respectively formed into a constitution, wherein an electric wire consisting of a conductor 4 covered with a insulating coating 3 is wound in the radius direction to form doughnut- shaped flat coils and these coils are stacked in the verticaldirection to connect continuously the coils with each other. Moreover, recessed grooves, which are opened in the end surfaces of the insulator 8, are respectively provided in the upper and lower end parts of the insulator 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer using a perfluorocarbon (PFC) liquid as a cooling medium to fill a tank in order to insulate and cool a winding installed in the tank.

[0002]

2. Description of the Related Art A transformer to which the present invention is applied includes an iron core,
An inner winding that is arranged concentrically with the iron core, an outer winding that surrounds the inner winding, an insulator that is arranged in the gap between the two windings, and a tank that houses these iron core to each winding, It is composed of a cooling medium filled in the tank.

Conventionally, in a transformer using oil as a cooling medium, the insulation between the inner winding and the outer winding is arranged in multiple layers with oil and insulation alternately arranged (oil gap subdivision system). ing. This is because when the total of the gaps excluding the thickness of the insulator from the distance between the two windings is constant, multiple insulators and smaller gaps in each oil gap will increase the dielectric strength. Therefore, the oil gap subdivision method is used in a transformer in which the interval between both windings is widened to some extent.

[0004]

PFC according to the present invention
The transformer uses perfluorocarbon (PFC) as a cooling medium.
Use liquid. At present, the production volume of PFC liquid is small,
It is more expensive than oil. Therefore, PFC transformers are more expensive than oil-filled transformers.

Unlike oil, PFC liquid is nonflammable,
The PFC transformer containing the PFC liquid has excellent safety and is particularly useful in locations where fires are strictly prohibited, such as underground substations in cities. However, it is expensive in price,
It is a big obstacle to the spread of PFC transformers.
Therefore, reducing the cost of PFC transformers is one of the major challenges in development, and this is an urgent task in terms of future development.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a PFC having a structure suitable for reducing the filling amount of the cooling medium as compared with the current oil-filled transformer. To provide a transformer.

A second object of the present invention is to provide a PFC transformer having a structure suitable for reducing the filling amount of PFC liquid and relaxing electrolytic concentration at the winding end.

[0008]

In order to achieve the first object, the first PFC transformer of the present invention comprises a columnar iron core, an inner winding arranged concentrically with the iron core, The outer winding that surrounds the inner winding and an insulator that is installed as a partition wall between the two windings are housed in a tank filled with perfluorocarbon (PFC) liquid. In the PFC transformer, in which the gap between the wall of the PFC transformer and the gap between the outer winding and the other wall of the insulating part are used as liquid channels for the perfluorocarbon (PFC) liquid, the insulator forms one partition wall, and The directional cross section is rectangular and solid.

In order to achieve the above-mentioned second object, the second PFC transformer of the present invention, like the first PFC transformer, has a columnar core, an inner winding, an outer winding, and a partition wall. Of the present invention, a tank filled with a perfluorocarbon (PFC) liquid, and a liquid passage, the insulating material forms one partition wall, and the cross section in the thickness direction is a shape having grooves open at the upper and lower ends respectively to the end side. It is characterized by

[0010]

In the first PFC transformer of the present invention, since the insulator between the inner winding and the outer winding has one solid rectangular cross section, a double bulkhead is provided rather than a conventional double bulkhead insulator. The volume occupied by the PFC liquid in the tank is reduced by the amount of the gap between them.

Further, in the second PFC transformer, since the insulator between the inner winding and the outer winding has one cross-sectional shape having grooves open at the upper and lower ends, respectively, the conventional double coil is not provided. As compared with the insulator of the partition wall, the tightening volume of the PFC liquid in the tank is reduced by the volume corresponding to the cross section from the bottom of the upper and lower grooves. Further, since the PFC liquid enters the groove by providing the groove, it is possible to relieve the electric field concentration at the winding end portion. This is based on the principle shown below. For example, when a voltage difference occurs between two windings (high-voltage winding and low-voltage winding), the potential distribution (electric field) changes depending on the composition between the windings. The distribution is determined by the permittivity of each constituent. The higher the permittivity, the sparser the electric field, and the smaller the permittivity, the denser the electric field. The dielectric constant of PFC liquid is smaller than that of insulator. In the winding of the transformer which is actually used, the portion facing the winding is provided with a liquid passage for cooling. First PF
In the case of the C transformer, since the space between the windings excluding the liquid passage is filled with an insulating material, the electric field is concentrated on the liquid passage facing the winding, and particularly the electric field is concentrated on the corners of the winding ends. It is known that when the electric field is excessively concentrated, dielectric breakdown occurs from the site. In order to prevent this, in the second PFC transformer, it is possible to avoid the concentration of the electric field by decreasing the proportion of the insulator and increasing the proportion of the liquid in the portion facing the winding end portion.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A PFC transformer according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a partial view showing the shape of an insulator between windings in one embodiment of the present invention, FIG. 2 is a view showing the shape of an insulator between windings in another embodiment, and FIG. 3 is a general view. Sectional view showing the overall configuration of a simple PFC transformer,
FIG. 4 is a diagram showing a shape of a conventional insulating material between windings for comparison.

First, the overall structure of a general PFC transformer will be described with reference to FIG. PFC transformer, PFC liquid 7
In the tank 11 filled with
An inner winding 2 arranged concentrically with the outer winding 1, an outer winding 1 installed around the inner winding, and an insulator 9 multiply placed like a partition between the inner winding 2 and the outer winding 1, Contains 9 etc. The iron core 12 is vertically positioned and fixed by an upper clamp 13 and an upper clamp 17, and the inner winding 2 and the outer winding 1 are vertically fixed via upper and lower insulators 15 and 16, respectively. It is fixed to.

Next, referring to FIG. 1, the structure of the insulator between the windings in one embodiment of the present invention will be described. The PFC transformer of this embodiment has the same structure as the PFC transformer shown in FIG.
This is the same as the configuration shown in FIG. In FIG. 1, one insulator 8 is installed as a partition wall between the inner winding 2 and the outer winding 1. The gap formed between the inner winding 2 and one surface of the insulator 8 and the gap formed between the outer winding 1 and the other surface of the insulator 8 are liquid passages 5 through which the PFC liquid flows. The inner winding 2 and the outer winding 1 are formed by winding an electric wire made of a copper body 4 covered with an insulating coating 3 in the radial direction to form a donut-shaped flat coil, and stacking these in the vertical direction to form each coil. Are connected continuously.

Here, the insulator 8 of one embodiment shown in FIG.
Is the insulator 9 in the conventional oil-filled transformer shown in FIG.
Compare with 9. The insulator 8 shown in FIG. 1 is a single plate in which the gap between the insulators 9 and 9 (same as shown in FIG. 1) shown in FIG. 11
The amount of PFC liquid in the inside can be reduced, and the cost of the PFC transformer can be reduced.

In FIG. 1, an electric field 6 indicated by a curve represents the potential difference generated between the outer winding 1 and the inner winding 2 as a distribution when a higher potential is applied to the outer winding 1. It is a thing. The electric field is higher where the intervals of the curves are closer and the electric field is lower where the intervals are sparse. Also, in a substance with a high dielectric constant (eg, an insulator), the electric field becomes sparse,
The electric field becomes dense in a substance with a low dielectric constant (eg PFC liquid). In FIG. 1, as compared with FIG. 3, it can be seen that the electric field is concentrated in the liquid portion having a lower dielectric constant and further in the corners of the winding end portions. It is known that there is a high possibility that dielectric breakdown will occur from this concentrated portion of the electric field, and depending on the specifications such as the voltage of the PFC transformer, the structure of the insulator 8 of one embodiment may not be adopted. This measure will be described below.

FIG. 2 is a view showing an insulator provided as a partition wall between the outer winding and the inner winding in another embodiment of the present invention. At the ends between the windings where the electric field is concentrated, P having a low dielectric constant is used.
Increasing the proportion of FC liquid is effective as a method of relaxing the electric field at the corners of the winding ends. Therefore, the insulating material as the partition wall is provided with concave grooves 14 that open to the end side at the upper and lower ends thereof.
The structure is such that the PFC liquid enters here. This insulation groove 1
4 is a short insulator 10 between two long insulators 9.
It can be easily manufactured by joining. Thus, the ratio of the liquid to the ends between the windings can be increased and the electric field concentration at the ends of the windings can be relaxed. By adopting this structure, it is possible to reduce the amount of liquid and alleviate the concentration of electric field at the same time.

[0018]

As described above, according to the present invention, the insulator provided as the partition between the inner winding and the outer winding is integrated by filling the gap of the conventional double wall with the insulator. ,
Since it has a solid cross section, the filling amount of the perfluorocarbon (PFC) liquid in the PFC transformer can be reduced as compared with the case of the double wall. In addition, by providing the upper and lower end portions of the insulator with the concave groove that opens to the end surface, the PF that has entered the concave groove
The liquid C can alleviate the electric field concentration that occurs at the winding ends. Thus, by reducing the cost of the PFC transformer using the non-flammable PFC liquid, it is possible to promote the installation of the PFC transformer in a place where the damage of the fire is great, such as an underground substation, and the installation place can be made safer.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a shape of an insulator between inner and outer windings in a PFC transformer according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a shape of an insulator between inner and outer windings in another embodiment of the present invention.

FIG. 3 is an overall configuration diagram of a general PFC transformer.

FIG. 4 is a cross-sectional view of an oil gap subdivision structure between inner and outer windings used in a conventional oil-filled transformer.

[Explanation of symbols]

 1 Outer Winding 2 Inner Winding 3 Insulation Coating 4 Conductor 5 Liquid Channel 6 Electric Field 7 PFC Liquid 8 Insulation 9 Insulation 10 Insulation 11 Tank 12 Iron Core 14 Recessed Groove

Claims (2)

[Claims] 1. A columnar iron core, an inner winding arranged concentrically with the iron core, an outer winding surrounding the inner winding, and an insulator provided as a partition wall between the both windings. It is housed and configured in a tank filled with a perfluorocarbon (PFC) liquid, and has a gap between the inner winding and one wall surface of the insulator and the outer winding and the other wall surface of the insulating portion. A PFC transformer using a gap as a liquid path for a perfluorocarbon (PFC) liquid, wherein the insulator is one partition wall and has a solid rectangular cross-section in the thickness direction. 2. A columnar iron core, an inner winding arranged concentrically with the iron core, an outer winding surrounding the inner winding, and an insulator provided as a partition wall between the both windings. It is configured to be housed in a tank filled with a perfluorocarbon (PFC) liquid, and has a gap between the inner winding and one wall surface of the insulator and the outer winding and the other wall surface of the insulating portion. In a PFC transformer in which a gap serves as a liquid passage for a perfluorocarbon (PFC) liquid, the insulator is one partition wall, and has a thickness-direction cross section having grooves open at the upper and lower ends, respectively. And a PFC transformer.