JP2000114069A - Resin-molded transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of cracks and voids between primary and secondary windings by making the coefficient of thermal expansion of a spacer formed between the windings nearly equal to that of a resin body filled into a container and composed of a filler and a thermosetting resin. SOLUTION: The main body 12 of a resin-molded transformer is constituted by winding a primary winding 2 around an insulating pipe 10 by using the pipe 10 as a core and inserting a secondary winding 3 into the pipe 10, and then, Combining the pipe 10 with an iron core 4 and the main body 12 is set up in a container 1. Then the container 1 is filled up with a resin body 7 composed of a filler and a thermosetting resin. The coefficient of thermal expansion of the resin body 7 is made nearly equal to that of the pipe 10 by making the compounding ratio of the filler and thermosetting resin forming the resin body 7 nearly equal to that of the filler and thermosetting resins forming the pipe 10. Therefore, the thermal stress caused by heat cycles can be relieved and no crack occurs. Therefore, the capital investment for the mold to be used only for making the insulating pipe 10 can be saved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outdoor resin mold transformer, and more particularly to a resin mold transformer in which cracks and voids do not occur between windings.

[0002]

2. Description of the Related Art When a resin mold transformer is used outdoors, if the mold surface is exposed to the outside air,
The dielectric strength of the mold surface is reduced due to ultraviolet deterioration or fouling of the thermosetting resin. Therefore, generally, the resin mold portion of the outdoor resin mold transformer is housed in a metal container.

FIG. 4 is a sectional view showing the configuration of a conventional resin mold transformer, and FIG. 5 is a perspective view showing the primary winding and the secondary winding of FIG. In FIG.
Inside a metal container 1, 1 is coaxially wound around an iron core 4.
The transformer main body 12 including the secondary winding 2 and the secondary winding 3 is housed. The primary winding 2 is connected to the container 1 via a high voltage lead 5.
And the secondary winding 2 is drawn out of the container 1 through the low-voltage lead 6. As shown in FIG. 5, a plurality of insulating spacers 9 are interposed between the primary winding 2 and the secondary winding 3 to secure an insulating gap between the windings. The space in the container 1 is filled with a resin body 7 indicated by dots as shown in FIG.

The filling of the resin body 7 into the container 1 is performed as follows. First, the transformer main body 12 is assembled in the container 1. Next, the gap in the container 1 is filled with an inorganic powdery filler. In this state, the inside of the container 1 is evacuated, and a liquid thermosetting resin is injected from a pipe 8 below the container 1 as shown by an arrow A and mixed with the filler. The thermosetting resin is heated together with the container 1 after being filled in the container 1. Thereby, the thermosetting resin is cured together with the filler, and the resin body 7 is obtained.

As the thermosetting resin, for example, Nagase CH
XN1019 / XN1124 manufactured by IBA is used,
This resin has flexibility like rubber even after curing.
As the filler, for example, silica sand or alumina particles are used so that the coefficient of thermal expansion of the resin body 7 is as close to metal as possible. That is, since the resin body 7 has flexibility and its thermal expansion coefficient is close to that of a metal, the interface with the metal does not easily peel off even when the temperature changes.

[0006]

However, the conventional device as described above has a problem that cracks and voids are easily generated between the primary winding 2 and the secondary winding 3. That is, as shown in FIG. 5, the thermal expansion coefficient of the spacer 9 interposed between the primary winding 2 and the secondary winding 3 is different from that of the resin body injected into the gap later. Cracks were easily generated at the interface of the spacer 9 by the heat cycle. For this purpose, it was necessary to wind a glass tape around the primary winding 2 and the secondary winding 3 in advance and provide a buffer layer. Therefore, the production cost by winding the glass tape has been extremely high.

Although the electric field is highest between the primary winding 2 and the secondary winding 3, a partial discharge is generated due to voids generated between the windings when the resin is cast, that is, voids. It was easy to perform, and the defective rate of production was high. The purpose of this invention is
An object of the present invention is to provide a resin mold transformer in which cracks and voids do not occur between windings without winding a glass tape.

[0008]

According to the present invention, in order to achieve the above object, a spacer formed in advance is interposed between a primary winding and a secondary winding, and the first and second spacers are interposed. A transformer main body in which a secondary winding and a secondary winding are wound around an iron core is housed in a metal container, and after this container is filled with an inorganic filler, flexible thermosetting is performed. In a resin mold transformer in which a thermosetting resin is injected and heat-cured, the coefficient of thermal expansion of the spacer is substantially the same as the coefficient of thermal expansion of the resin body made of the filler and the thermosetting resin filled in a container. There should be something. Thereby 1
Since the insulating space between the secondary winding and the secondary winding is occupied by a material having substantially the same coefficient of thermal expansion, thermal stress due to a heat cycle is relaxed and cracks do not occur. In the case where the spacer is manufactured by casting a thermosetting resin, the casting mold needs to be smaller than the container in which the transformer body is stored. Can be cast. In such a configuration, the spacer may be an insulating cylinder. Thus, since only one insulating cylinder is used as the spacer, the number of necessary spacers is reduced as compared with the configuration using a plurality of spacers such as square rods, and assembly is facilitated.

Further, in such a configuration, it is preferable that the insulating cylinder is formed of a uniform material from the outer periphery to the inner periphery. As a result, the insulating space between the primary winding and the secondary winding is occupied by only one member of a uniform material, namely, one insulating cylinder. Thermal stress due to the heat cycle is further reduced.

In this configuration, the spacer or the insulating tube may be formed from the filler and the thermosetting resin at substantially the same mixing ratio as the resin body. In this configuration, a layer made of an FRP cylinder may be provided on at least one of the outer circumference and the inner circumference of the insulating cylinder. Thereby, since the mechanical strength of the FRP cylinder is high, the short-circuit strength of the winding is improved. Further, in such a configuration, a layer made of an FRP cylinder may be provided on both sides of the outer circumference and the inner circumference of the insulating cylinder. Thus, the FRP cylinder can be used as a casting mold, and there is no need to manufacture a mold dedicated to the insulating cylinder.

[0011] In the above construction, a part of the insulating cylinder other than the layer composed of the FRP cylinder is formed from the filler and the thermosetting resin at substantially the same mixing ratio as the resin body. It can be.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 is a sectional view showing a configuration of a resin mold transformer according to an embodiment of the present invention, and FIG.
FIG. 2 is a perspective view showing the insulating tube 10 taken out. An insulating cylinder 10 as shown in FIG. 2 is interposed between the primary winding 2 and the secondary winding 3 in FIG. In other respects, the configuration is the same as the conventional configuration, and the same portions are denoted by the same reference characters, and detailed description will be omitted.

In FIG. 1, the insulating cylinder 10 can be manufactured, for example, as follows. That is, the insulating tube 10
The same filling material as that used for the resin body 7 in FIG. 1 is filled in a casting mold designed and manufactured to have a predetermined size and shape for use, and is subjected to preliminary drying and heating. Then, the resin body 7
The same thermosetting resin used for thermosetting resin,
For example, a flexible thermosetting resin X manufactured by Nagase CHIBA
Vacuum impregnation at 80 ° C., 1 mbar with N1019 / XN1124 and pressurization at 3 atm, followed by 80 ° C.
The insulating cylinder 10 is formed through heat curing at + 130 ° C. for 5 hours for 6 hours. The compounding ratio of the filler and the thermosetting resin forming the insulating cylinder 10 is substantially the same as the compounding ratio of the filler and the thermosetting resin in the resin body 7.

Using this insulating tube 10 as a winding core, the primary winding 2 is wound, the secondary winding 3 is inserted inside the insulating tube 10, and combined with the iron core 4 to form the transformer body 12. ,
Installed in the container 1. After that, the container 1 is filled with a filler for the resin body 7. The above example is an example in which the material forming the insulating cylinder 10 is the same as the filler for the resin body 7 and the thermosetting resin, and the mixing ratio is also the same. If the same thermal expansion coefficient as that of the resin body 7 can be provided, a material different from that of the resin body 7 may be used, and the mixing ratio may be different.

The insulating tube 10 manufactured in advance as described above
Is inserted between the primary winding 2 and the secondary winding 3 before the filling material is filled in the container, so that the space between the primary winding 2 and the secondary winding 3 is increased. Since the insulating space is occupied by a material having substantially the same thermal expansion coefficient, the thermal stress due to the heat cycle is alleviated and cracks do not occur. Also, as in the past, 1
A filler is uniformly filled between the secondary winding 2 and the secondary winding 3,
In addition, impregnating the voidless with a thermosetting resin is very difficult because of its large volume. The casting mold dedicated to the insulating tube 10 is a container 1 in which the transformer body 12 is stored.
It is easier to impregnate the void dress, since it is smaller.

Table 1 shows the results of measuring the characteristics of the resin-molded transformer of the embodiment of FIG. 1 and the conventional example of FIG.

[0017]

[Table 1] 性 Characteristics Example (Fig. 1) Conventional example (Fig. 4) ──────────────────────────────────── Resin injection time 30 minutes 40 minutes Partial discharge start Voltage> 8kV 7.8kV Noise level 32dB 40dB Heat cycle property -40 ℃ ⇔ No crack at 100 ℃ -10 ℃ ⇔ No crack at 100 ℃ -20 ℃ ⇔ Crack at 100 ℃ ──────────に お い て In Table 1, the reason why the resin injection time of the example is shorter than that of the This is because it is molded.
The reason why the partial discharge starting voltage of the embodiment is higher than that of the conventional example is that the insulating cylinder is formed in a voidless manner.
The heat cycle property of the embodiment is superior to that of the conventional example. That is, according to the heat cycle test at −20 ° C.⇔100 ° C., in the case of the conventional example, along the interface between the spacer 9 (FIG. 4) between the primary winding 2 and the secondary winding 3 and the resin body 7. Cracks. On the other hand, in the case of the embodiment,
Cracks did not occur at all in the heat cycle test at ℃. This is because, as described above, the insulating space between the primary winding 2 and the secondary winding 3 is occupied by a material having substantially the same thermal expansion coefficient, so that the internal thermal stress is reduced.

By adopting the structure of the embodiment shown in FIG. 1, cracks and voids do not occur.
It is not necessary to provide a buffer layer by winding a glass tape around the secondary winding 2 and the secondary winding 3 in advance, so that the manufacturing cost can be reduced. FIG. 3 is a perspective view showing a configuration of an insulating cylinder of a resin mold transformer according to another embodiment of the present invention. A layer of an FRP cylinder 11 made of a fiber-reinforced plastic material is provided on both sides of the outer circumference and the inner circumference of the insulating cylinder 10. Others are the same as the configuration of FIG. Fiber reinforced plastic (fiber-glass reinfor
Ced plastic is obtained by impregnating a glass fiber or the like with a resin and curing the resin, and is a material having extremely high mechanical strength. Therefore, the winding of the resin mold transformer according to the embodiment of FIG. 3 is very strong against mechanical force, and can sufficiently withstand the mechanical force generated between the windings when a short circuit occurs.
Therefore, the reliability of the resin mold transformer is remarkably improved. If the coefficient of thermal expansion of the FRP tube 11 is set to be substantially the same as the coefficient of thermal expansion of the insulating tube 10 other than the FRP tube 11, the generation of internal thermal stress due to the intervention of the FRP tube 11 can be avoided.

The layers of the FRP cylinder 11 shown in FIG. 3 are provided on both sides on the outer and inner circumferences of the insulating cylinder 10.
This layer may be provided on only one of the outer periphery and the inner periphery of the insulating tube 10, whereby the mechanical strength of the winding is improved. However, as shown in FIG.
By providing one layer on both sides of the outer circumference and the inner circumference of the insulating cylinder 10, in addition to the improvement of mechanical strength,
There is also an advantage that the FRP cylinder 11 itself can be used as a casting mold. Therefore, there is no need to manufacture a mold dedicated to the insulating cylinder 10, and the equipment cost of the mold can be reduced.

In the embodiment shown in FIGS. 1 to 3, the spacer interposed between the primary winding and the secondary winding is configured as an insulating cylinder. The spacer may be composed of a plurality of square bar-shaped spacers or the like, provided that the thermal expansion coefficient of the square rod-shaped spacer is substantially the same as the thermal expansion coefficient of the resin body 7. Good.

[0021]

According to the present invention, as described above, the primary winding
A spacer formed in advance is interposed between the coil and the next winding, and the thermal expansion coefficient of the spacer is substantially the same as the thermal expansion coefficient of a resin body made of a filler and a thermosetting resin filled in the container. By doing so, cracks and voids do not occur, and the manufacturing cost is reduced. Further, in such a configuration, by using the insulating cylinder as the spacer, the number of necessary spacers is reduced, and assembly is facilitated.
Further, in such a configuration, the insulating cylinder is formed of a uniform material from the outer periphery to the inner periphery, so that heat can be generated at any position in the insulating space between the primary winding and the secondary winding. The expansion coefficients become equal, and the thermal stress due to the heat cycle is further reduced. Further, in such a configuration, by providing a layer made of the FRP cylinder on at least one of the outer circumference and the inner circumference of the insulating cylinder, the short-circuit strength of the winding is increased, and the reliability is improved. . Further, in such a configuration, by providing a layer made of the FRP cylinder on both sides of the outer circumference and the inner circumference of the insulating cylinder, it is possible to save equipment costs for a mold dedicated to the insulating cylinder. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a resin mold transformer according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the insulating cylinder of FIG. 1 taken out therefrom;

FIG. 3 is a perspective view showing a configuration of an insulating cylinder of a resin mold transformer according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a configuration of a conventional resin mold transformer.

FIG. 5 is a perspective view showing the primary winding and the secondary winding of FIG. 4 taken out therefrom;

[Explanation of symbols]

1: container, 2: primary winding, 3: secondary winding, 4: iron core, 1
0: Insulation cylinder, 11: FRP cylinder, 12: Transformer body

Claims (7)

[Claims] A transformer formed by interposing a spacer formed in advance between a primary winding and a secondary winding and winding the primary winding and the secondary winding around an iron core. In a resin mold transformer in which a container main body is housed in a metal container and a flexible thermosetting resin is injected and heat-cured after the container is filled with an inorganic filler, the spacer Wherein the coefficient of thermal expansion of the resin mold is substantially the same as the coefficient of thermal expansion of the resin body made of the filler and the thermosetting resin filled in the container. 2. The resin mold transformer according to claim 1, wherein said spacer is an insulating cylinder. 3. The resin mold transformer according to claim 2, wherein said insulating cylinder is formed of a uniform material from its outer periphery to its inner periphery. 4. The resin-molded transformer according to claim 1, wherein the spacer or the insulating cylinder is formed from the filler and the thermosetting resin at substantially the same mixing ratio as the resin body. A resin molded transformer characterized by being performed. 5. The resin mold transformer according to claim 2, wherein a layer made of an FRP cylinder is provided on at least one of the outer circumference and the inner circumference of the insulating cylinder. 6. The resin-molded transformer according to claim 5, wherein a layer made of an FRP cylinder is provided on both sides of an outer circumference and an inner circumference of the insulating cylinder. 7. The resin mold transformer according to claim 5, wherein a portion of the insulating cylinder other than a layer made of an FRP cylinder is formed of the filler and the thermosetting resin. A resin molded transformer characterized by being formed with substantially the same blending ratio as that of the above.