JPH05190350A - Foil-wound transformer - Google Patents

Abstract

PURPOSE:To provide a reliable, high-voltage high-capacity transformer with improved cooling efficiency and mechanical strength. CONSTITUTION:A transformer tank contains a coil of a metal foil 2 and an insulating sheet 3 wound together on a core arm 1, and the tank is filled with insulating gas at a predetermined pressure. Ribs 9c are provided in parallel with the coil axis between metal layers of the transformer coil, and the ribs serve to form channels of cooling gas at regular intervals between two metal panels 9a and 9b. In addition, a cooling panel 9 of the same radius of curvature as the periphery of the coil is inserted to form a cooling duct to cool the coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foil winding transformer in which a cooling duct is formed between appropriate winding layers of a winding in which a metal sheet and an insulating sheet are superposed and wound.

[0002]

2. Description of the Related Art In recent years, substations are often installed in the suburbs of cities or underground due to restrictions on their installation sites. Therefore, the demand for flame retardancy is even higher for transformers installed in substations in such places.

Therefore, in recent years, in place of the conventional oil-filled transformer, there has been a gas-insulated transformer for insulating and cooling the transformer by using an insulating gas such as SF ₆ gas having an excellent insulating property as an insulating cooling medium. It has been put to practical use.

However, this gas-insulated transformer has the drawback of being inferior in cooling characteristics to the conventional oil-filled transformer. That is, the specific heat and heat exchange efficiency of the insulating gas are considerably lower than those of the insulating oil.

Loss L (kW) generally generated in the winding
And the cooling medium amount Q (l / min) flowing in the winding per unit time for cooling the winding, and the temperature difference (ΔT) of the cooling medium at the inlet and outlet of the winding, ΔT = 1 / (k · C _p · r) × (L / Q) (1) k: Constant (kW / kcal / min) C _p : Specific heat of cooling medium (kcal / kg · ° C.) r: Cooling medium The specific gravity (kg / l) is related.

By substituting the physical constants into the equation (1), the value of {1 / (k · C _p · r)} is about 6500 to 7 when SF ₆ gas is used as the cooling medium.
It will be about 000. On the other hand, when insulating oil is used as the insulating medium, this value is about 35, which is about 1/200 of the value when SF ₆ gas is used.

That is, in the case of a gas-insulated transformer, if the same loss occurs in the winding as in the oil-filled transformer and the circulating amount of the cooling medium is also the same, the temperature difference between the upper and lower sides of the winding is oil-filled. It will reach 200 times that of a transformer.

As described above, in a gas-insulated transformer having a low cooling efficiency, in order to cool the winding with high efficiency, it is required that a large amount of SF ₆ gas, which is a cooling medium, be sent to the winding without a break. To be done.

Conventionally, there is a foil winding transformer having a structure as shown in FIG. 3 in order to meet this demand. As shown in FIG. 3, a low-voltage winding 4 and a high-voltage winding 5, which are obtained by stacking and winding a metal sheet 2 and an insulating sheet 3 on an iron core leg portion 1, are coaxially wound. A plurality of cooling ducts 6 serving as flow paths for the cooling medium are provided in the axial direction 5 in the axial direction. In this case, these windings 4 and 5 are made of metal sheet 2 and insulating sheet 3 as shown in FIG.
And are overlapped and wound, and a plurality of insulating spacers 8 elongated in the width direction of the metal sheet 2 are provided between the appropriate winding layers, and the duct sheet 7 made of an insulating material is provided at equal intervals in the longitudinal direction. By overlapping and winding the lower side of the metal sheet 2, the cooling ducts 6 are formed in the low-voltage winding 4 and the high-voltage winding 5 so as to escape in the axial direction.

As a constituent member of the cooling duct 6, there is known one in which duct pieces are adhered and fixed as insulating spacers 8 on a surface of a duct sheet 7 made of an insulating material as shown in FIG. The thus-configured transformer contents are housed in a transformer tank (not shown) and filled with insulating gas at a predetermined pressure.

[0011]

However, the conventional foil wound transformer using the cooling duct as described above has the following problems.

(1) Since the duct pieces are arranged at right angles in the width direction in contact with the metal sheet 2, when a short-circuit mechanical force is applied to the winding, the metal sheet 2 is deformed between the duct pieces and the cooling duct 6 may be blocked. Also,
If the upper or lower duct flow passage inlet or outlet is blocked due to deformation of the insulating sheet 3 or the metal sheet 2 at the winding end, or other reasons, cooling of the duct cannot be expected.

(2) When a plurality of cooling ducts 6 are arranged, it is difficult to align the duct pieces in the radial direction of the winding, and the strength of the entire winding against the short-circuit mechanical force is reduced.

(3) The smaller the pitch of the duct pieces, the less the problems (1) and (2) are solved, but the contact area between the cooling medium and the metal sheet is reduced correspondingly, so that the cooling efficiency is lowered. (4) The insulating material changes in length and thickness due to drying shrinkage and deterioration over time, and the winding is likely to loosen.

As described above, in the conventional foil wound transformer, there is a problem in the structure of the cooling duct 6, and it has been desired to develop a cooling duct having excellent cooling efficiency and high strength against short-circuit mechanical force. An object of the present invention is to provide a compact, highly reliable, high-voltage, large-capacity foil wound transformer that improves cooling efficiency and is resistant to short-circuit mechanical force.

[0016]

In order to achieve the above object, the present invention winds a foil-shaped winding formed by winding a metal sheet and an insulating sheet on a leg of an iron core in a transformer tank. In a foil wound transformer in which the contents of the mounted transformer are housed and an insulating gas is sealed at a predetermined pressure, between two metal panel plates between appropriate winding layers of the foil winding. Cooling is performed by providing rod-shaped spacers for forming cooling gas passages at regular intervals in the winding axis direction and inserting a gas cooling panel that is curved according to the outer circumference of the winding portion. The cooling duct was also formed.

[0017]

In the foil wound transformer having such a structure, the strength against the short-circuit mechanical force at the time of a short circuit can be increased, and in terms of cooling characteristics, the material in contact with the metal sheet is made of an insulator to a metal plate. As a result, heat conduction is significantly improved and efficiency is improved as compared with the conventional case. As a result, the size of the winding can be minimized for cooling, and the size can be reduced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a foil winding transformer according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a winding portion wound around an iron core leg of a foil winding transformer according to the present invention. The same parts as those in FIG. 3 are designated by the same reference numerals. In FIG. 1, a low-voltage winding 4 and a high-voltage winding 5 are coaxially wound around an iron core leg 1, and a plurality of cooling medium flow paths are formed in the windings 4 and 5 with appropriate intervals. Gas cooling panels 9 are respectively provided in the axial direction. As shown in FIG. 2, this gas cooling panel 9 has two ribs 9c made of a rod-shaped insulator extending in the width direction sandwiched between two metal panel plates 9a and 9b and welded to each other to form a shaft. The gas duct 10 is formed in the direction. In this case, the gas cooling panel 9 is curved according to the outer circumference of the winding portion. The thus-configured transformer contents are housed in a transformer tank (not shown) and filled with insulating gas at a predetermined pressure.

Therefore, in the foil wound transformer having the above structure, the following effects can be obtained by inserting the gas cooling panel 9 between the winding layers of the low voltage winding 4 and the high voltage winding 5 as appropriate. be able to.

(A) At the time of manufacturing the winding, conventionally, the duct pieces are displaced due to a tensile force during the winding, and it is difficult to align the duct pieces in the radial direction of the winding. However, in this embodiment, the rib 9 having a welded structure is used.
By using c, the deviation does not occur, the cooling duct can be secured, and the strength against the short-circuit mechanical force can be improved. (B) There is almost no change in dimensions such as length and thickness due to drying shrinkage or deterioration over time, and loosening of the winding can be suppressed to a minimum. (C) When a short-circuit mechanical force is applied to the winding, the panel has significantly higher mechanical strength than the conventional duct sheet made of an insulating material, and thus the reliability is improved.

(D) Conventionally, the winding is cooled by gas through an insulator, but the gas cooling panel 9 is used to cool the winding through the metal panel plates 9a and 9b. , Heat conduction is improved and cooling efficiency is improved.

In the above embodiment, the rod-shaped rib 9c is arranged between the two metal panel plates 9a and 9b so as to be welded to the panel plates. A protrusion may be formed and this protrusion may be used as a rod-shaped spacer.

[0024]

As described above, according to the present invention, the gas cooling panel is inserted into the winding in which the metal sheet and the insulating sheet are superposed and wound, so that the cooling efficiency is improved.
It is possible to provide a highly reliable high-voltage, large-capacity foil winding transformer having improved strength against mechanical short circuit force.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a winding cooling structure in an embodiment of a foil winding transformer according to the present invention.

FIG. 2 is a perspective view showing a configuration of a gas cooling panel according to the embodiment.

FIG. 3 is a cross-sectional view showing a cooling structure for windings in a conventional foil winding transformer.

FIG. 4 is a perspective view showing a duct sheet used in a conventional foil winding transformer.

FIG. 5 is a perspective view of a winding structure showing a state in which a duct sheet is inserted into a winding in a conventional foil winding transformer.

[Explanation of symbols]

1 ... Iron core leg, 2 ... Metal sheet, 3 ... Insulation sheet, 4 ... Low-voltage winding, 5 ... High-voltage winding, 9 ... Gas cooling panel, 9a, 9b ... Panel plate, 9c ... ... ribs, 10
...... Gas duct.

Claims (1)

[Claims] 1. A transformer tank, in which a foil-shaped winding formed by stacking a metal sheet and an insulating sheet on a leg portion of an iron core is wound in a transformer tank, and at a predetermined pressure. In a foil wound transformer filled with insulating gas, cooling gas passages are formed between two metal panel plates at appropriate intervals in the winding axis direction between appropriate winding layers of the foil winding. A foil winding transformer is provided with a rod-shaped spacer for forming a cooling duct for cooling the winding by inserting a gas cooling panel which is curved according to the outer circumference of the winding portion.