JP2018113381A - Power transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transformer that reduces loss of the main body and eliminates problems due to loss concentration and a local temperature rise in a lower iron core fastener.SOLUTION: In a power transformer that includes a plurality of iron core legs 1, an upper iron core part 2 and a lower iron core part 3 disposed at upper and lower ends of the iron core leg 1, a winding 4 wound around the iron core leg 1, an upper iron core clamping metal fitting 5 and a lower iron core clamping metal fitting 6 which are disposed at the upper and lower ends of the winding 4 and sandwich the winding 4, and a tank 7 that houses the iron core legs 1, the upper iron core part 2, the lower iron core part 3, the winding 4, the upper iron core clamping metal fitting 5, and the lower iron core clamping metal fitting 6, the surface of the winding 4 of the lower iron core clamping metal fitting 6 is made of an insulator 15 and the power transformer further includes a support member 14 of the winding 4.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a transformer that can reduce loss due to leakage magnetic flux from a transformer winding.

  Due to the recent increase in power demand, transformers tend to have larger capacities. Accordingly, the leakage magnetic flux from the transformer winding tends to increase. The increase in loss due to leakage magnetic flux causes a local temperature rise inside the transformer, which is problematic from the viewpoints of deterioration of insulators and reduction of cooling efficiency of transformer oil.

  In particular, the lower core fasteners arranged near the windings have a large loss due to a large amount of leakage magnetic flux from the windings. As a method for reducing the loss in the lower iron core fastener, Patent Document 1 discloses a method of arranging a magnetic shield on the lower iron core fastener. According to the present invention, by arranging the magnetic shield on the side surface on the side opposite to the iron core of the lower iron core fastening bracket, it is possible to effectively reduce the generated loss due to the leakage magnetic flux in the lower iron core fastener.

  In Patent Document 2, a magnetic shield made of a non-magnetic material is arranged on the winding side of the lower iron core fastening bracket, and a magnetic shield made of a ferromagnetic material is arranged on the non-winding side of the lower iron core fastening fitting. To do. These magnetic shields control the flow of magnetic flux in the vicinity of the lower iron core clamp and reduce the loss caused by the leakage magnetic flux from the winding.

JP 60-57911 A JP 2014-60235 A

  In order to connect and fix the iron core and the lower iron core fastener to the lower iron core fastener, a working hole is provided on the side surface on the side opposite to the iron core, and a lid for closing the hole is installed. In a structure like patent document 1, there exists a subject that it is difficult to arrange | position the magnetic shield of an integrated object on the side surface by the side of the anti-core core of a lower iron core clamp.

  In order to solve this problem, in Patent Document 2, a magnetic shield is disposed on the winding surface and the non-winding surface of the lower iron core fastening fitting to control the flow of leakage magnetic flux. However, since the oil feeding hole is provided on the winding side of the lower iron core fastening bracket for cooling the winding, it is necessary to process the oil shield to provide the oil feeding hole, which increases the number of work steps. In addition, when a magnetic shield is applied to the winding surface and the non-winding surface of the lower iron core clamp, the transformer size increases by the thickness of the magnetic shield, and the transformer weight and material cost increase.

  The present invention has been made in view of the above points, and the object of the present invention is to reduce the loss of the transformer body, and to reduce the loss of the transformer core and reduce the temperature of the product due to local temperature rise. Provide a transformer that eliminates defects.

  The present invention includes a plurality of core legs, upper and lower cores disposed at upper and lower ends of the core legs, windings wound around the core legs, and upper and lower ends of the windings. In a transformer composed of an upper iron core fastening bracket and a lower iron core fastening metal fitting that are disposed between and holding the winding, and a tank that accommodates these, the surface of the winding of the lower iron core fastening metal is insulated. It is comprised by the thing, Furthermore, the support member of the said coil | winding was provided, It is characterized by the above-mentioned.

  According to the transformer of the present invention, it is possible to reduce the loss in the lower iron core fastening bracket that has a large loss due to the leakage magnetic flux from the winding. Further, it is possible to prevent problems due to excessive loss concentration and local temperature rise in the lower iron core fastening bracket.

It is the figure which showed typically the flow of the leakage magnetic flux produced from the coil | winding of the transformer which has a lower iron core fastening metal fitting. FIG. 3 is a cross-sectional view of a main part of the transformer in the first embodiment. It is the figure which showed typically the electromagnetic force of the coil circumferential direction which acts on a coil | winding at the time of a winding short circuit. It is the figure which showed typically the electromagnetic force of the coil axial direction which acts on a coil | winding at the time of a winding short circuit. It is an example of the T-shaped support member provided in order to support the coil | winding in Example 1. FIG. 2 is an example of a plate-like support member provided to support the winding in Example 1. FIG. It is sectional drawing which shows the transformer of the three-phase five-legged iron core structure in Example 1 from upper direction. It is the figure which showed the structure of the lower iron core fastening metal fitting in Example 1. FIG. It is the figure which showed the magnetic flux leakage from a coil | winding while showing the transformer of the three-phase five-legged iron core structure in Example 2 from upper direction. In Example 2, it is the figure which showed typically the eddy current which generate | occur | produces with the magnetic flux linked to the support member for supporting a coil | winding. In Example 2, it is the figure which showed typically the eddy current which flows through a support member, when a slit is given to the support member for supporting a coil | winding.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram schematically showing the flow of leakage magnetic flux generated from a winding of a transformer having a lower iron core fastener. As shown in FIG. 1, the transformer is composed of an iron core leg 1, an upper iron core 2, a lower iron core 3, a winding 4, an upper iron clamp 5, a lower iron clamp 6, and a transformer tank 7. The The lower iron core fastening bracket 6 includes a side surface on the iron core side, an upper surface on the winding side, a side surface on the anti-iron core side, and a lower surface on the anti-winding side. An oil feed hole 8 for cooling the winding 4 is provided on the upper surface of the lower iron core fastening fitting 6.

  Further, an iron core support 9 for supporting the iron core leg 1 and an anti-winding side of the lower iron core fastening bracket 6 are fastened and fixed to the side surface of the lower iron core fastening bracket 6 on the side opposite to the iron core. A working hole 10 is provided. In order to close the working hole 10 and secure the cooling oil passage 20, a lid 11 is provided on the outer side of the lower iron core fastening fitting 6 on the side opposite to the iron core.

  The leakage magnetic flux 50 from the winding 4 flows into the lower iron core portion 3 through the lower iron core fastening fitting 6 as indicated by an arrow. The upper surface of the lower iron core fastening fitting 6 is opposed to the winding 4, and many leakage magnetic fluxes 50 are linked. Therefore, the loss due to the eddy current generated in accordance with the amount of change in the interlinkage magnetic flux is increased on the upper surface of the lower iron core fastening bracket 6.

  The upper surface of the lower core fastening metal fitting 6 has a structure in close contact with the insulator 13 of the winding support portion. Therefore, the loss generated on the upper surface of the lower iron core fastening bracket 6 is difficult to be cooled, and if an excessive loss occurs, the insulator 13 of the winding support may be damaged.

  Hereinafter, the configuration of the present embodiment will be described with reference to FIG. In this figure, the same parts as those in FIG. The upper surface of the lower iron core fastening fitting 6 is constituted by an insulator 15. In consideration of strength and workability, the insulator 15 used on the upper surface of the lower core fastening metal fitting 6 is preferably a press board, phenol resin, FRP, or insulating wood. Further, since the lower iron core clamp 6 has the function of the cooling oil passage 20, the insulator 15 and the lower iron core clamp 6 need to be in close contact with each other. 15 is joined with a bolt or an adhesive. The adhesive is preferably, for example, an epoxy resin, a silicone resin, or a fluororubber adhesive. By applying the above structure, it is possible to significantly reduce the loss caused by the leakage magnetic flux 50 from the winding 4 interlinking with the lower iron core fastening bracket 6.

  3 and 4 show the electromagnetic force 32 acting on the winding 4 including the primary winding 30 and the secondary winding 31. The direction of the arrow indicating the electromagnetic force 32 indicates the direction of the electromagnetic force 32. As shown in FIG. 3, the electromagnetic force 32 acts on the winding 4 in the horizontal direction. When the horizontal electromagnetic force 32 acts on the winding 4, the winding 4 is also deformed in the vertical direction and vibrates as shown in FIG. 4. The vertical vibration of the winding 4 is applied to the lower iron core fastening bracket 6 via the insulator 13 of the winding support shown in FIG.

  As shown in FIG. 2, when the upper surface of the lower iron core fastening bracket 6 is formed of the insulator 15, the insulator 15 may be damaged due to vibration caused by the electromagnetic force 32. When the insulator 15 is damaged, the insulating medium 12 may leak from the cooling oil passage 20 and the winding 4 may not be efficiently cooled. Therefore, the lower iron core fastening fitting 6 is provided with a support member 14 for supporting the weight of the winding 4 and the electromagnetic force 32. In view of strength, the support member 14 may be, for example, a structure in which a metal T-shaped support member 40 as shown in FIG. 5 is provided in the lower iron core fastener, or a lower iron fastener as shown in FIG. It is desirable to have a structure in which a plate-like support member 41 is provided in a portion facing the winding on the upper surface of 6. The lower iron core fastening fitting 6 and the winding support member 14 are connected by welding, for example.

  FIG. 7 shows a plan view of the main part of the three-phase five-legged core structure of FIG. 1 viewed from above. The support member 14 of the winding 4 provided in the lower iron core fastening bracket 6 is intended to support the weight of the winding 4 and the electromagnetic force 32 applied from the winding 4, and is therefore disposed immediately below the winding 4. Is desirable. In addition, an oil feed hole 8 for cooling is provided in the portion of the upper surface of the lower iron core clamp 6 facing the winding 4 to cool the winding 4, and the insulating medium 12 is connected to the winding 4. Sent. As shown in FIG. 8, the insulator 15 disposed on the upper surface of the lower core fastening bracket 6 is provided on a portion of the upper surface of the lower core fastening bracket 6 where the support member 14 of the winding 4 is not disposed. .

  In the structure of the present embodiment, the metal plate constituting the upper surface of the lower iron core fastening fitting 6 can be omitted, so that the weight can be reduced as compared with the conventional structure. Further, in the conventional structure, it is necessary to provide the oil feed hole 8 for cooling the winding 4 in the metal plate used on the upper surface of the lower iron core fastening bracket 6, but in the structure shown in this embodiment, the processing is not performed. The oil feeding hole 8 may be provided in a relatively easy insulator, and workability is improved. Furthermore, since the loss reduction effect can be expected by adopting the configuration of the present embodiment, the transformer can be designed to be small and light.

  FIG. 9 is a diagram showing the transformer having the three-phase five-legged core structure in the second embodiment from above, and the leakage magnetic flux from the windings is shown by arrows. In the transformer of the three-phase five-legged core structure having the lower iron core fastening fitting 6, the support member for the winding 4 is formed of a plate-like member. The support member is made of a ferromagnetic material to form a ferromagnetic support member 16. As the ferromagnetic material, for example, a silicon steel plate can be considered. Further, a slit as shown in FIG. 11 is formed on the surface of the support member of the winding 4. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Hereinafter, the flow of the leakage magnetic flux 50 generated from the winding of the present embodiment will be described with reference to FIG. Most of the leakage magnetic flux 50 generated from the winding 4 passes through the ferromagnetic support member 16 of the winding 4 made of a ferromagnetic material and the lower iron core fastening bracket 6 as shown by the arrow, and the other phase or the lower portion. It flows into the iron core 3. Since the support member of the winding 4 is made of a ferromagnetic material, the leakage magnetic flux 50 from the winding 4 interlinked with the side surface of the lower core fastening bracket 6 can be reduced. The loss in the side face can be reduced.

  The leakage magnetic flux 50 flowing through the interphase part (between the windings) of the lower iron core fastening bracket 6 passes through the ferromagnetic support member 16 of the winding 4 disposed immediately below the winding 4, and the winding 4 of the other phase. To flow. 10 and 11 are plan views of the main part of the lower iron core fastening fitting 6 as viewed from above. As shown in FIG. 10, an eddy current 61 flows through the ferromagnetic support member 16 of the winding 4 due to the leakage magnetic flux 50. FIG. 10 shows a leakage magnetic flux 50 that flows upward in the drawing. As a result, eddy current loss occurs in the ferromagnetic support member 16 of the winding 4. In order to suppress this eddy current loss, a slit 60 shown in FIG. 11 is provided on the surface of the ferromagnetic support member 16 of the winding 4. By reducing the loop of the eddy current 61, the eddy current loss generated in the ferromagnetic support member 16 of the winding 4 can be reduced.

  As described above, a ferromagnetic material is used for the support member of the winding 4, and further, the slit 60 is provided on the surface thereof, so that the side surface of the lower core fastening bracket 6 and the ferromagnetic support member 16 of the winding 4 are provided. Loss can be reduced. As a result, it is possible to suppress the occurrence of excessive loss and temperature rise as compared with the first embodiment. The ferromagnetic support member 16 in this embodiment may be a T-shaped support member as shown in FIG.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1: Iron core leg part 2: Upper iron core part 3: Lower iron core part 4: Winding 5: Upper iron core fastening metal fitting 6: Lower iron core fastening metal fitting 7: Tank 8: Oil feed hole 9: Iron core support base 10: For work Hole 11: Lid 12: Insulating medium 13: Insulator of winding support 14: Support member 15: Insulator 16: Ferromagnetic support member 20: Oil passage for cooling 30: Primary winding 31: Secondary winding 32 : Electromagnetic force 40: T-shaped support member 41: Plate-like support member 50: Leakage magnetic flux 60: Slit 61: Eddy current

Claims (6)

Multiple core legs,
An upper iron core portion and a lower iron core portion disposed at upper and lower ends of the iron core leg portion;
A winding wound around the iron core leg,
An upper core fastening bracket and a lower core fastening bracket disposed at the upper and lower ends of the winding and sandwiching the winding; and
In a transformer composed of a tank that houses these,
A transformer comprising: a surface of the winding of the lower core fastening metal fitting made of an insulator; and a support member for the winding. The transformer according to claim 1,
A transformer characterized in that the support member is composed of a T-shaped support member. The transformer according to claim 1,
A transformer characterized in that the support member is composed of a plate-like member. The transformer according to claim 3,
A transformer further comprising a ferromagnetic material as the support member. The transformer according to any one of claims 1 to 4,
A transformer characterized in that the support members are arranged at a plurality of locations on the upper surface of the lower core fastening metal fitting. The transformer according to any one of claims 1 to 5,
A transformer having a slit on a surface of the support member.

Images