Patent Application
20230133073
The present disclosure relates to an electrical insulator for a fluid-filled inductive device.
A fluid-filled inductive device, e.g. a transformer, comprises solid insulation and cooling fluid. A sufficient circulation of the cooling fluid is needed for efficient cooling of the inductive device. Thus, the solid insulation should allow the cooling fluid to pass and circulate in the device. For example, the top and bottom winding insulators, so called winding tables or pressplates, may be comprised in arrangements of several separate but combined parts, i.e. pressplates and common spacer rings, to allow the cooling fluid to pass the solid insulation.
It is an objective of the present disclosure to provide an improved electrical insulator for an inductive device 1 filled with an electrically insulating cooling fluid, for allowing the fluid to pass the insulator.
According to an aspect of the present disclosure, there is provided an electrical insulator. The insulator is configured to be used in an inductive device filled with an electrically insulating cooling fluid. The insulator defines a plurality of internal channels for allowing the electrically insulating cooling fluid to flow there through to improve circulation of the fluid within the inductive device.
According to an aspect of the present disclosure there is provided an electrical insulator, for an inductive device filled with an electrically insulating cooling fluid, the insulator defining a plurality of internal channels for allowing the fluid to flow there through to improve circulation of the fluid within the inductive device,
wherein the insulator is flat and the channels comprise radial channels extending in a plane within the insulator which is parallel to opposing first and second main surfaces of the insulator,
wherein the channels comprise axial channels, each of the axial channels extending through at least one of the first and second main surfaces and into at least one of the radial channels for allowing the cooling fluid to pass between the axial and radial channels
and wherein the insulator is made of at least one electrically insulating material comprising a composite material of fibres, e.g. synthetic fibres such as glass fibres, in a resin matrix, e.g. comprising a curable resin such as an epoxy or polyester resin, preferably epoxy.
According to another aspect of the present disclosure, there is provided an inductive device comprising a housing, an electrically insulating cooling fluid contained within the housing, a winding arrangement submerged in the cooling fluid, and at least one insulator of the present disclosure.
By the insulator having internal channels for the cooling fluid, the circulation of the cooling fluid can be improved without the need for spacers or the like which would increase the spatial footprint of the insulator. The insulator, and thus the whole inductive device, may be made more compact.
It is to be noted that any feature of any of the aspects may be applied to any other aspect, wherever appropriate. Likewise, any advantage of any of the aspects may apply to any of the other aspects. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, step, etc.” are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. The use of “first”, “second” etc. for different features/components of the present disclosure are only intended to distinguish the features/components from other similar features/components and not to impart any order or hierarchy to the features/components.
Embodiments will be described, by way of example, with reference to the accompanying drawings, in which:
Embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments are shown. However, other embodiments in many different forms are possible within the scope of the present disclosure. Rather, the following embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout the description.
The insulator 5 may be cellulose based, e.g. pressboard or wood/wood laminate, synthetic, e.g. aramid or epoxy based, and/or a laminate or composite. The insulator may e.g. comprise a fibre-resin composite of fibres, e.g. synthetic fibres such as glass fibres, in a resin matrix, e.g. comprising a curable or otherwise hardenable resin such as an epoxy or polyester resin, preferably epoxy.
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Internal channels 6 may reduce the mechanical strength of the insulator 5, why it may in some embodiments be advantageous to use a fibre-resin composite material in the insulator to improve mechanical strength without increasing the thickness of the insulator. Thus, the first outer layer 31 and/or the second outer layer 33 may be made of a composite material of fibres in a resin matrix. The inner layer 32 may e.g. comprise spacers fastened (e.g. glued) to the first and second outer layers to form internal (radial) channels 6, which spacers may be of the same composite material or of another suitable material e.g. cellulose-based such as pressboard or wood. The fibres are typically electrically insulating, e.g. synthetic fibres such as glass fibres. The resin is typically a hardenable resin such as a curable or thermosetting resin, e.g. an epoxy or polyester resin, preferably an epoxy resin.
According to an embodiment of the present disclosure, an electrical insulator 5, for an inductive device 1 is filled with an electrically insulating cooling fluid 3, the insulator defining a plurality of internal channels 6 for allowing the fluid 3 to flow there through to improve circulation of the fluid within the inductive device.
In some embodiments of the present disclosure, the insulator 5 is flat and the channels 6 comprise or consist of radial channels extending in a plane within the insulator, which plane is parallel to opposing first and second main surfaces 21 and 22 of the insulator. In some embodiments, the insulator 5 has an inner edge surface 24 defining a central through hole 9 through the insulator, said through hole being perpendicular to the plane of the insulator, in which plane the radial channels 6 extend. In this case, each of the radial channels 6 may extend from an outer (outward facing) edge surface 23 of the insulator to the inner edge surface 24 of the insulator. Additionally or alternatively, in some embodiments, the channels 6 comprise axial channels 34, where each of the axial channels extends through at least one of the first and second main surfaces 21 and 22 and into at least one of the radial channels for allowing the cooling fluid to pass between the axial and radial channels (i.e. each of the axial channels has an inlet or outlet into/out from the a radial channel).
In some embodiments of the present disclosure, the insulator 5 is made of at least one electrically insulating material comprising a cellulose-based material, e.g. pressboard or wood laminate, preferably pressboard.
In some embodiments of the present disclosure, the insulator 5 is made of at least one electrically insulating material comprising a composite material of fibres, e.g. synthetic fibres such as glass fibres, in a resin matrix. The resin matrix may comprise a curable resin such as an epoxy or polyester resin, preferably epoxy.
In some embodiments of the present disclosure, the insulator 5 is a laminate wherein the channels 6 are formed by means of spacers 32 arranged between first and second outer layers 31 or 33 of the insulator. In some embodiments, the first outer layer 31 and/or the second outer layer 33 is made of a composite material of fibres, e.g. synthetic fibres such as glass fibres, in a resin matrix. The resin matrix may comprise a curable resin such as an epoxy or polyester resin, preferably epoxy. In some embodiments, the spacers 32 are formed by a continuous corrugated layer arranged between the first and second outer layers 31 or 33. In some other embodiments, the spacers 32 are formed by discrete ribs arranged between the first and second outer layers 31 or 33.
In some other embodiments of the present disclosure, the channels 6 are bores in the insulator 5, typically formed by drilling.
In some embodiments of the present disclosure, the insulator 5 is arranged as a pressplate at the top and/or bottom of the winding arrangement 4.
In some embodiments of the present disclosure, the inductive device 1 is a transformer or a reactor, preferably a transformer.
In some embodiments of the present disclosure, the cooling fluid is a liquid, e.g. a mineral oil or ester liquid, preferably a mineral oil.
Embodiments of the present disclosure may be described in any one of the following points.
The present disclosure has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the present disclosure, as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20163757.6 | Mar 2020 | WO | international |
This application is a 35 U.S.C. § 371 national stage application of PCT International Application No. PCT/EP2021/056379 filed on Mar. 12, 2021, which in turn claims foreign priority to European Patent Application No. 20163757.6 filed on Mar. 17, 2020, the disclosures and content of which are incorporated by reference herein in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/056379 | 3/12/2021 | WO |
