JP2602550Y2 - Foil winding transformer - Google Patents

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 foil-wound coil having a cooling duct.

[0002]

2. Description of the Related Art As a conventional transformer, there is an insulating gas filled transformer using a foil winding type coil with a cooling duct as exemplified in FIGS. As illustrated in FIGS. 3 and 4, the coil portion of the coil in the transformer is provided with an insulating tube 2 wound around an iron core 1, a cooling duct 3 wound around its outer periphery, and an insulating tube thereon. The tube 4 is wound, the cooling duct 5 is wound thereon, and the low-voltage winding 6 is further wound thereon. A high-voltage winding 8 is wound around the low-voltage winding 6 via a cooling duct 7, a cooling duct 9 is wound thereon, and a high-voltage tap winding 10 is wound around the outside. Low voltage winding 6
The high-voltage winding 8 is formed by laminating and winding a copper or aluminum foil conductor and an insulator of a polyester film (PET). A plurality of cooling ducts 11 are provided between the layers 15 between the low-voltage winding 6 and the high-voltage winding 8.

The portion of each cooling duct 11 provided between the foil conductor layers 15 is configured as shown in FIG. That is, an insulator 13 is superimposed on a foil conductor 12 which is a peripheral side surface of one of the layers 15, and an aluminum corrugated member 14 in which an aluminum plate is formed into a corrugated shape is wound thereon to increase cooling efficiency. The body 13 is wound, and the foil conductor 12, which is the peripheral side surface of the other layer 15, is further wound thereon.

[0004]

In the conventional transformer as described above, the temperature of the coil portion becomes high during operation, and vibration occurs. Therefore, in the cooling duct portion between the layers 15, the mountain-shaped aluminum corrugated member 14 is formed. There has been a problem that the insulator 13 which is a polyester film that is in contact with the tip of the protrusion may be damaged, and dielectric breakdown may occur between the layers 15. The reason is as follows. The temperature characteristics of the polyester film used as the insulator 13 are shown in FIG.
And its softening point is about 80 ° C. During operation of the transformer, the temperature of the coil rises to 120 ° C., so that the hardness of the insulator 13 is reduced to about 33% of the normal temperature. The insulator 13 softened as described above is strongly pressed by the contact surface pressure at a portion in contact with the chevron-shaped head of the aluminum corrugated member 14 to be stretched and the thickness thereof becomes thin, that is, the insulator 13 becomes a so-called rough state. . In order to examine this state, the stress relaxation when the contact pressure was applied to the insulator 13 and the displacement was made constant was measured, and the test result shown in FIG. 7 was obtained. Thus, when the contact surface pressure over the entire surface of the aluminum corrugated member 14 is 0.2 kg / cm ² , the contact surface pressure does not decrease with the passage of time at room temperature, but the temperature is 105 ° C.
It can be seen that the contact surface pressure immediately decreases when the temperature is raised to ° C.

As described above, if the thickness of the insulator 13 at the contact portion with the aluminum corrugated member 14 is reduced, even in the case of a coil that is firmly wound during manufacturing, the cooling duct portion will be loosened. In such a state, the aluminum corrugated member 14 is excited by the excitation vibration generated during the operation of the transformer.
Vibrates, and the insulator 13 in contact with the crest of the chevron is worn and damaged, causing dielectric breakdown.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to newly provide a transformer in which insulation breakdown does not occur in a cooling duct portion of a coil.

[0007]

According to the transformer of the present invention, a corrugated member is provided in a cooling duct of a coil portion of a foil winding type coil, and at least between the corrugated member and the foil winding,
Aramid paper or softening point is characterized by being configured by interposing Porii Mi de film above 130 ° C., or a heat-resistant insulating material of the prepreg or the like where the resin is applied to these.

[0008]

According to the above construction, even if the temperature of the coil portion rises to the normal operation temperature during the operation of the transformer and the vibration occurs, the heat-resistant insulator is hardly worn and damaged. To prevent.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a transformer according to the present invention will be described below with reference to FIGS. In FIGS. 1 and 2, parts corresponding to those of the conventional example shown in FIGS. 3 to 7 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 shows a cooling duct portion provided between layers of a foil conductor in a foil winding type coil portion of the transformer of the present embodiment.
Numeral 12 is a foil conductor, numeral 13 is an insulator, and numeral 14 is an aluminum corrugated member installed in a cooling duct, which is configured as follows. An insulator 13 is superimposed on a foil conductor 12 which is a peripheral side surface of one of the layers, and a heat-resistant insulator 16 is wound thereon, and its outer surface is directed into the cooling duct. Further, in order to increase the cooling efficiency of the cooling duct, an aluminum corrugated member 14 formed by corrugating an aluminum plate is wound on the surface of the heat-resistant insulator 16. Then, a heat-resistant insulator 16 serving as an outer surface facing the inside of the cooling duct in the other layer is wound thereon, an insulator 13 is stacked thereon and wound thereon, and a foil conductor 12 is wound thereon.

As the heat-resistant insulator 16, aramid paper (aromatic polyamide paper) is used in this embodiment. The untreated aramid paper may be used, or an aramid paper prepreg coated with a resin on the surface to form a sesicle may be used.

The inter-layer insulator 13 of the entire coil may be used in place of the heat-resistant insulator 16. In this case, the thickness of the aramid paper as the heat-resistant insulator 16 is 75 mm.
Since the diameter is more than micron, the coil diameter becomes large and the cost becomes high. For this reason, in this example, in the aluminum corrugated member 14
The heat-resistant insulator 16 is provided only between the layers of the cooling duct into which the air enters.

As shown in FIG. 2, the relationship between the tensile strength and the temperature of this aramid paper does not have a softening point and is about 120%.
Even if it is heated to ℃, the decrease in strength is about 15% and does not become soft. Unlike a conventional polyester film which is an insulator, there is no sag at a portion which is in pressure contact with the aluminum corrugated member 14, and the heat resistance is excellent.

A comparison was made between the conventional structure using only the polyester film in the cooling duct portion containing the aluminum corrugated member of the coil and the structure using the aramid paper of the present embodiment in terms of vibration durability. It was confirmed that this example had better durability.

Further, when an aramid paper prepreg is used as the heat-resistant insulator 16 in place of the aramid paper, the heat-resistant insulator 16 and the chevron-shaped top of the aluminum corrugated member 14 may be connected to each other during the drying process in the coil manufacturing process. It can be firmly bonded and integrated to improve structural reliability.

In the embodiment described above, the heat-resistant insulator 1 is used.
It has been described using aramid paper as 6, which not only, a softening point may be used poly <br/> Lee Mi de film over 130 ° C..

[0016]

As described above in detail, according to the transformer of the present invention, a corrugated member is installed in a cooling duct of a foil-winding type coil portion, and at least an aramid is provided between the corrugated member and the foil winding. paper or softening point 130 ° C. or more ports <br/> Rii Mi de film, or since it is configured by interposing the heat insulator prepreg such that the resin is applied thereto, usually the coil portion during operation of the transformer Even if the temperature rises to the temperature at the time of operation and vibration occurs, the heat-resistant insulator is not worn and damaged, so that there is an effect that dielectric breakdown can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an embodiment of a transformer according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between tensile strength and temperature of aramid paper in the above embodiment.

FIG. 3 is a longitudinal sectional view of a main part illustrating a coil part of a foil winding type coil of a conventional insulating gas filled transformer.

FIG. 4 is a cross-sectional view of a main part of the conventional example.

FIG. 5 is a cross-sectional view of an aluminum corrugated cooling duct portion in the coil portion of the conventional example.

FIG. 6 is an explanatory diagram showing a change in dynamic tensile elasticity of a polyester film in the conventional example with temperature.

FIG. 7 is an explanatory diagram showing a stress relaxation test result of a contact portion between an aluminum corrugate and a polyester film in the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Iron core 11 ... Cooling duct 12 ... Foil conductor 14 ... Aluminum corrugated member 15 ... Layer 16 ... Heat resistant insulator

Claims (1)

(57) [Scope of request for utility model registration] 1. A foil-winding transformer in which a cooling duct is formed by an aluminum corrugated member insulated by an insulator inside a foil winding in which a foil conductor and a film-shaped insulator are superposed and wound. the insulator in contact with the corrugated members, aramid paper, poly Lee bromide film having a softening point of 130 ° C. or higher,
Alternatively, a foil-wound transformer using a prepreg heat-resistant insulator coated with a resin.