JP2533508Y2 - Oil-filled transformer - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-immersed transformer using an iron core made of an amorphous magnetic alloy ribbon.

[0002]

2. Description of the Related Art Recently, amorphous magnetic alloys have been attracting attention as low-loss iron core materials, and transformers for power distribution using amorphous magnetic alloy ribbons (hereinafter also simply referred to as ribbons) have been manufactured. Is being transformed.

[0003] Since the amorphous magnetic alloy ribbon after the magnetic annealing is very brittle and easily chipped, there is a possibility that fragments of the ribbon may be generated when an external force is applied. If strip debris adheres to the windings or floats in the oil, the insulation of the transformer is threatened. Therefore, when an iron core made of an amorphous magnetic alloy ribbon is used, the outer surface of the iron core is wrapped with a protective cover made of an insulating material to protect the iron core and, when a ribbon fragment is generated, the fragment is formed. Is taken out of the iron core.

[0004]

[Problems to be Solved by the Invention] When the outer surface of the iron core is covered with the protective cover, air is restrained inside the protective cover, or impregnation of the insulating oil into the iron core is not completely performed. Problems are easy to occur.

When the protective cover covering the iron core is made of insulating paper or the like, air or insulating oil flows through gaps and the like at the overlapping portion, but the speed is slow. Therefore, when performing vacuum degassing and lubrication, there are problems that the degree of vacuum in the tank is deteriorated and that it takes time to reach a predetermined degree of vacuum.

In a conventional oil-immersed transformer using a wound iron core made of an amorphous magnetic alloy ribbon, various techniques for covering the iron core with a protective cover have been proposed. No particular consideration was given to the discharge of air from inside and the impregnation of insulating oil into the iron core.

Japanese Patent Application Laid-Open No. 64-68912 describes that the air inside the protective cover is replaced with insulating oil. However, in the transformer described in this earlier application,
Since air and insulating oil do not flow directly from the lamination surface of the joint portion of the iron core, air flows only from the lamination surface of the corner portion of the upper yoke which is the joining side (the side having the joining portion). The flow rate of insulating oil is slow.

SUMMARY OF THE INVENTION An object of the present invention is to provide an oil-immersed transformer having a wound core formed by winding an amorphous magnetic alloy ribbon, which prevents fragments of the ribbon from coming off the core, and a protective cover for lubrication. An object of the present invention is to make it possible to promptly discharge air between the iron core and the inside of the iron core, so that the insulating oil can quickly penetrate into the iron core.

[0009]

According to the present invention, the protective cover for covering the wound core has a hole at a portion facing the laminated surface of the upper yoke and the lower yoke of the wound core, and the hole of the protective cover is provided. Are covered with a breathable sheet material.

The air-permeable sheet is a sheet-like material that allows the passage of fluids such as air and insulating oil, but prevents the passage of solids such as thin strips. As such a sheet-like material, for example, a cotton cloth, a nonwoven fabric, or the like can be used.

[0011]

In the oil-immersed transformer of the present invention, the behavior of air and insulating oil during lubrication is as follows.

In the case of vacuum lubrication, air between the iron core and the protective cover and in the iron core flows out of the upper and lower holes of the protective cover, and the insulating oil also penetrates into the iron core from the upper and lower holes of the protective cover. I do.

In the case of normal pressure lubrication, most of the air between the iron core and the protective cover and in the iron core is discharged from the upper hole of the protective cover, and most of the insulating oil flows from the lower hole of the protective cover. Penetrates into the iron core.

[0014] As described above, the replacement of the air inside the protective cover with the insulating oil and the impregnation of the insulating oil into the iron core are performed quickly and completely.

The air-permeable sheet material attached to the protective cover prevents the passage of solids such as strip fragments, so that the strip fragments may be removed during lubrication and during transportation and operation of the transformer thereafter. There is no danger of leaking out of the core.

[0016]

FIG. 1 is a front view of an oil-immersed transformer according to an embodiment of the present invention, showing only a part of the transformer, and FIG.
FIG. 6 is a front view showing a state before the winding 2 is fitted to the horn. 3 is a sectional view taken along the line III-III in FIG. 2, and FIG.
FIG. 4 is a sectional view taken along line IV-IV of FIG.

In FIG. 1, 1 is an iron core, 2 is a winding, and 3 is a protective cover covering the outer surface of the iron core. The iron core 1 is a substantially rectangular wound iron core in which a number of amorphous magnetic alloy ribbons are stacked.

The wound iron core 1 is a substantially rectangular wound iron core comprising an upper yoke, a lower yoke, and left and right legs, and a winding 2 is fitted to each of the left and right legs. In this embodiment, the lower yoke is the joining side 1a.

The joint side is a four-sided iron core having a substantially rectangular shape.
Among the sides, one side has a thin band joint J (see FIG. 2). In the state shown in FIG. 2 before the winding is fitted to the iron core 1, three sides except the joint side 1a of the iron core are covered with the protective cover 3, and the protective cover is still attached to the joint side 1a. Absent.

In this embodiment, the lower yoke is the joining side, but it goes without saying that the upper yoke may be the joining side.

As shown in FIGS. 3 and 4, in this embodiment, an inner protection plate 5 and an outer protection plate 6 are provided along the inner and outer peripheral surfaces of the iron core 1, respectively.
As the inner protection plate 5 and the outer protection plate 6, a plate made of a material which is thicker than a thin ribbon and is mechanically strong, for example, a steel plate or a stainless steel plate is suitable. The inner protective plate and the outer protective plate are not essential to the present invention, but are desirably provided to protect the ribbon which becomes extremely brittle by annealing.

The protective cover 3 is formed by winding insulating paper such as kraft paper around the outer surface of the iron core. The protective cover 3 protects the iron core from external force and also prevents thin strip fragments from coming out of the iron core. is there. Since various types of protective covers have been proposed (for example, Japanese Patent Application Laid- Open No. 2-266504 ), a detailed description of the configuration of the protective cover will be omitted, and only the features of the present invention will be described.

In the present invention, the protective cover 3 has a large number of holes 3a at positions facing the laminated surface (the end surface in the width direction of the ribbon) of the upper yoke and the lower yoke of the iron core. A breathable sheet material 4 that covers the entire portion provided with the hole 3a is disposed between the iron core 1 and the protective cover 3 (see FIG. 4).

The air permeable sheet material 4 allows the passage of fluids such as air and insulating oil freely, but prevents the passage of solids such as thin strip fragments. Etc. are appropriate. The permeable sheet material 4 has its peripheral edge fixed to the protective cover 3 with an adhesive or the like.

A portion of the protective cover including the portion where the hole 3a is provided and the permeable sheet material 4 will be referred to as a permeable portion V. The ventilation portions V are provided at two locations in the upper yoke and two locations in the lower yoke, for a total of four locations. Vent V
Are arranged near the center of each of the two lamination surfaces of each yoke of the iron core in the longitudinal direction (lateral direction in FIG. 1), and at the joining side 1a, most of each lamination surface of the joining portion J It faces the ventilation part V.

In the present specification, a portion structurally integrated with the iron core 1, that is, a portion composed of the iron core 1, the protective cover 3, the inner protective plate 4, the outer protective plate 5, and the air-permeable sheet material 6 is referred to as the iron core. It will be referred to as constituent 7. FIG. 3 shows that the core structure 7 is
FIG. 4 is a cross-sectional view showing a cross-section at a position deviating from the center, and FIG.

In FIG. 4, the indication of the state of adhesion of the permeable sheet material 4 to the protective cover 3 is omitted, but the upper and lower ends of the portion of the permeable sheet material 4 shown in FIG. , Is adhered to the protective cover. 3 and 4, the illustration of the inner protective plate 5 and the outer protective plate 6 is omitted.

When fitting the windings to the core structure 7 shown in FIG. 2, the joint J is opened once, and the windings 2, 2 are fitted to the left and right legs of the core structure 7. Then, the joint J is closed again. FIG. 5 shows a state where the winding 2 is fitted to the iron core structure 7 shown in FIG. 2 and the joint J is closed. As shown in FIG.
Is closed, the air permeable sheet material 7 and the protective cover 3 are attached to the joint side 1a to complete the iron core structure 7.

In the above embodiment, the ribbon constituting the wound core is very thin, having a thickness of only 20 μm to 30 μm, and one of the two front and back surfaces of the ribbon is a free surface. However, the flatness of the surface of the ribbon is not good. for that reason,
The space factor of the iron core using the ribbon is low.

Further, in the joint portion J of the wound core made of a thin ribbon, a gap larger than the gap of the joined portion of the wound core made of a silicon steel strip is generally generated. Therefore, the wound core using the thin ribbon has more space portions inside than the wound core using the silicon steel strip having the same volume.

In a wound iron core using a ribbon, there are many spaces between the iron core and a protective cover covering the outer surface thereof. These spaces are filled with air before lubrication, and the air is replaced with insulating oil during lubrication.

Although the replacement of air with insulating oil is slightly different depending on the lubrication method, the transformer of the present invention can completely and promptly replace the air with insulating oil.

When vacuum lubrication is performed, air inside the iron core and between the iron core and the protective cover escapes from the upper and lower ventilation parts V, and the insulating oil also permeates into the iron core from the upper and lower ventilation parts V.

In the case of normal pressure lubrication, most of the air inside the iron core and between the iron core and the protective cover is discharged from the upper ventilation part V, and most of the insulating oil permeates into the iron core from the lower ventilation part V. I do.

Incidentally, if the ventilation portion is only on the upper yoke side, it takes a long time to replace the air with the insulating oil, and if the ventilation portion is only on the lower yoke side, the air is protected from the iron core. And within the iron core (particularly in the case of normal pressure lubrication).

Since the portion of the wound core having the most space is the region of the joint J, if the joint J and the ventilation portion V are arranged at the same position, the flow resistance of air and insulating oil can be reduced. The replacement of the air with the insulating oil can be completed in a short time. Therefore, when the ventilation portion V faces the laminated surface of the joint J as in this embodiment, it is possible to promptly replace the air and the insulating oil in the iron core and between the iron core and the protective cover. it can.

The air permeable sheet material 6 stuck to the inner surface of the protective cover 3 prevents the passage of solids such as thin strips and the like. In operation, the thin strip fragments do not leak out of the core.

FIG. 6 shows a modification of the present invention.
In this example, the shape of the ventilation portion V1 is different from the shape of the ventilation portion V in FIG. 1, but the basic operation and effect of the ventilation portion are the same as in the above-described embodiment.

In the example of FIG. 6, the hole 3a1 of the protective cover is rectangular, and only one hole 3a1 is provided in each ventilation part V1. Hole 3a1 in one ventilation part V1 in FIG.
The area of the hole 3 in one ventilation part V in FIG.
This corresponds to the sum of the areas of the aggregate of a.

In FIG. 6, the air-permeable sheet material 4-1 has a shape larger than the hole 3a1 of the protective cover, and this air-permeable sheet material is connected to the iron core while protecting the hole 3a1 of the protective cover. It is arranged between the cover. The peripheral portion of the breathable sheet material 4-1 is adhered to the protective cover 3 with an adhesive or the like.

When the ventilation portion V is configured as shown in FIG. 6, the process of providing the hole of the protective cover can be simplified. When there is a possibility that the air-permeable sheet material 4-1 may be loosened or swelled in a portion inside the hole 3a1,
In addition to bonding the peripheral portion of the breathable sheet material 4-1 to the protective cover, the center of the breathable sheet material may be bonded to the iron core 1 in a spot manner.

In FIG. 6, the permeable sheet material is provided inside the protective cover. In the present invention, the holes provided in the protective cover may be covered with the permeable sheet material, and the permeable sheet material is protected. It may be provided outside the cover. FIG.
7 shows an embodiment in which a permeable sheet material is provided on the outside of the protective cover. In FIG. 7, V2 is a ventilation hole, and 3a2 is a rectangular hole provided for each ventilation hole V2. The portion 4-2 is a breathable sheet material provided so as to cover the hole 3a2 from outside the protective cover 3 and adhered to the periphery of the hole 3a2.

When the permeable sheet material is provided outside the protective cover as shown in FIG. 7, even if the permeable sheet material is thick, the protection cover can be easily attached to the iron core.

In the structure shown in FIG. 1, it goes without saying that the breathable sheet material may be provided outside the protective cover.

In the above embodiments, the sizes and shapes of the ventilation portions provided on the upper yoke side and the lower yoke side are the same, but the sizes and shapes of the ventilation portions may be different.

In general, the lamination thickness of the ribbon at the joining side is larger than the lamination thickness of the ribbon at the yoke on the opposite side. Therefore, when the size of the ventilation portion on the joining side is larger than the size of the ventilation portion on the opposite side of the joining side, the replacement of the air and the insulating oil can be performed more quickly.

In each of the above embodiments, a core type transformer is taken as an example. However, it is needless to say that the present invention can be similarly applied to a case of a shell type transformer. In the case of a shell-type transformer, four vents are provided in the upper yoke and four vents are used in the lower yoke.
A total of eight locations are provided.

[0048]

As described above, according to the present invention, a hole facing the laminated surface of the upper yoke and the lower yoke of the core is provided in the protective cover for covering the wound core made of the amorphous magnetic alloy ribbon. Since the hole is provided and the hole is covered with a breathable sheet material, the advantage that the replacement between the protective cover and the iron core and the air inside the iron core with the insulating oil can be performed promptly and completely. There is.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a main part of an oil-immersed transformer according to an embodiment of the present invention.

FIG. 2 is a front view showing an iron core structure used in the embodiment of the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is a front view showing a state where a winding is fitted to the iron core structure of FIG. 2;

FIG. 6 is a partially cutaway front view of a main body according to another embodiment of the present invention.

FIG. 7 is a partially cutaway front view of a main body according to still another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Iron core, 1a ... Joining side, 2 ... Winding, 3 ... Protective cover,
3a, 3a1, 3a2 ... holes, 4, 4-1, 4-2 ... air-permeable sheet material, 7 ... iron core structure, V, V1, V2 ... air-permeable parts, J ...
Joint.

Claims (1)

(57) [Scope of request for utility model registration] 1. An oil-immersed transformer having a core wound by winding an amorphous magnetic alloy ribbon, wherein the core is covered by a protective cover, and the protective cover is an upper yoke and a lower yoke of the core. An oil-immersed transformer characterized in that the oil-immersed transformer has a hole in a portion facing the lamination surface of the above, and the hole of the protective cover is covered with a breathable sheet material.