A cold-resistant transposed conductor

Abstract

The present invention proposes a cold-resistant transposed conductor, comprising a transposed core wire, a ceramic coating and an insulating layer, wherein the transposed core wire comprises a plurality of flat conductors arranged in a stacked transposed manner, the outer surface of the flat conductor is attached with a ceramic coating, the surface of the ceramic coating is attached with an insulating layer, and the ceramic coating is one of aluminum oxide, silicon nitride and zirconium oxide. The cold-resistant transposed conductor of the present invention can still maintain the insulation between single flat conductors under extremely cold conditions, and the use of ceramic coating for isolation can effectively avoid the problem of electrical performance degradation caused by damage to the insulating layer, and reduce the probability of increased eddy current loss caused by damage to the insulating layer of the transposed conductor under extremely cold conditions.

Description

Technical Field

[0001] The invention relates to the technical field of transposed conductors, and in particular to a cold-resistant transposed conductor. Background Art

[0002] Transposed conductor is a kind of conductor widely used in the winding of large power transformers. It is obtained by adopting a special winding structure of multiple strands of conductor, which can reduce the resistance loss of winding and reduce load loss. Since there is no external insulation layer and only an insulating paint film is set on the surface of the single strand of conductor, the transposed conductor has good heat dissipation performance.

[0003] However, in some extremely cold environments, the insulating paint film on the surface of the single-strand conductor of the transposed conductor is prone to brittleness, cracking, and falling off, which affects the electrical performance of the transposed conductor under extremely cold conditions.

[0004] Improving the cold resistance of transposed conductors has become one of the technical issues that need to be solved urgently. Summary of the invention

[0005] In view of this, the present invention proposes a cold-resistant transposed conductor, aiming to improve its cold-resistant performance by modifying the structure of the transposed conductor.

[0006] The technical solution of the present invention is implemented as follows: the present invention provides a cold-resistant transposed conductor, which comprises a transposed core wire, a ceramic coating and an insulating layer. The transposed core wire comprises a plurality of flat conductors arranged in a stacked transposed manner. The outer surface of each flat conductor is adhered to a ceramic coating, and the surface of the ceramic coating is adhered to an insulating layer. The ceramic coating is one of aluminum oxide, silicon nitride and zirconium oxide.

[0007] In some embodiments, the method for preparing the ceramic coating includes: placing the flat wire in an environment containing ceramic vapor, and obtaining the ceramic coating after deposition for a certain period of time.

[0008] In some embodiments, the insulating layer is a self-adhesive insulating layer, and the self-adhesive insulating layer is obtained by coating a self-adhesive insulating paint and curing it.

[0009] In some embodiments, a repair layer is further included, wherein the repair layer is attached to the surface of the ceramic coating, and the insulating layer is attached to the surface of the repair layer, and the repair layer is made of thermoplastic polyurethane.

[0010] In some embodiments, the preparation method of the repair layer includes: dissolving TPU particles in a solvent to obtain a TPU solution, coating the TPU solution on the ceramic coating surface of the flat conductor, and obtaining a repair layer attached to the ceramic coating surface after drying, wherein the solvent is tetrahydrofuran.

[0011] In some embodiments, the TPU particles used are aromatic thermoplastic polyurethane particles.

[0012] In some embodiments, the mass concentration of the TPU solution is 10-30%.

[0013] In some embodiments, the TPU solution further includes polyurethane elastic fibers, the mass concentration of the polyurethane elastic fibers is 0.1-1.0%, and the polyurethane elastic fibers are polyurethane fibers.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The cold-resistant transposed conductor of the present invention can still maintain the insulation between single flat conductors under extremely cold conditions, and the use of ceramic coating for isolation can effectively avoid the problem of electrical performance degradation caused by damage to the insulation layer, thereby reducing the probability of increased eddy current loss caused by damage to the insulation layer of the transposed conductor under extremely cold conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a cross-sectional view of a cold-resistant transposed conductor according to Embodiment 1 of the present invention;

[0018] Figure 2 This is a cross-sectional view of a cold-resistant transposed conductor according to Embodiment 2 of the present invention.

[0019] In the figure: 1- transposed core wire, 11- flat conductor, 2- ceramic coating, 3- insulation layer, 4- repair layer. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0023] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0024] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range. In the present specification and claims, range definitions can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0025] The present invention provides a cold-resistant transposed conductor, such as Figure 1 As shown, it includes a transposed core wire 1, a ceramic coating 2 and an insulating layer 3. The transposed core wire 1 includes a plurality of stacked and transposed flat conductors 11. The outer surface of the flat conductor 11 is adhered with a ceramic coating 2. The surface of the ceramic coating 2 is adhered with an insulating layer 3. The ceramic coating 2 is one of aluminum oxide, silicon nitride and zirconium oxide.

[0026] In the above embodiments, the ceramic coating 2 is mainly used to provide an insulating layer with more stable adhesion performance and stable cold resistance, and cooperates with the insulating layer 3 to play a protective and further insulating role. When the insulating layer 3 cracks and causes defects such as gaps under extremely cold conditions, due to the isolation effect of the insulating layer 3 and the protective effect of the ceramic coating 2, direct contact and conduction between adjacent flat wires 11 can be avoided.

[0027] In some embodiments, the method for preparing the ceramic coating 2 includes placing the flat wire 11 in an environment containing ceramic vapor, and obtaining the ceramic coating 2 after deposition for a certain period of time.

[0028] In the above embodiments, according to the materials of different ceramic coatings, corresponding ceramic materials are used for physical vapor deposition. Preferably, the thickness of the ceramic coating obtained by deposition is 0.1-0.5 μm.

[0029] In some embodiments, the insulating layer 3 is a self-adhesive insulating layer, which is obtained by coating and curing a self-adhesive insulating varnish.

[0030] In the above embodiments, the insulating layer 3 is a conventional self-adhesive insulating varnish, which is obtained by coating and curing the self-adhesive insulating varnish purchased on the market.

[0031] In some embodiments, a repair layer 4 is further included. The repair layer 4 is attached to the surface of the ceramic coating 2, and the insulating layer 3 is attached to the surface of the repair layer 4. The repair layer 4 is made of thermoplastic polyurethane.

[0032] In the above embodiments, the function of the repair layer 4 is to strengthen the insulating layer 3 and provide an organic substrate for the insulating layer 3 to prevent the insulating layer 3 from powdering and falling off due to stress fatigue under extremely cold conditions. At the same time, the repair layer 4 can repair cracks under the heat of the transposed conductor itself, so that the insulating layer 3 can maintain a certain adhesion and isolation effect.

[0033] In the above embodiment, the stress fatigue process and the repair process include: since the insulation layer 3 has a different expansion coefficient from the substrate, and since the repair layer 4 made of thermoplastic polyurethane material and the insulation layer 3 have the same number of layers, the bonding is relatively good. Under extremely cold conditions, the insulation layer 3 tends to shrink together with the repair layer 4. Since the repair layer 4 has a certain self-repairing ability when heated, after the transposed conductor is heated, the repair layer 4 has a tendency to self-repair and return to its original state, and the insulation layer 3 with good adhesion performance can be repaired under the self-repairing effect of the repair layer 4, thereby greatly reducing the risk of surface cracking damage and falling off.

[0034] In some embodiments, the preparation method of the repair layer 4 includes: dissolving TPU particles in a solvent to obtain a TPU solution, coating the TPU solution on the ceramic coating surface of the flat conductor, and obtaining a repair layer 4 attached to the ceramic coating surface after drying, wherein the solvent is tetrahydrofuran.

[0035] The use of TPU solution for coating can make the repair layer 4 thinner and avoid increasing the volume of the transposed conductor. Preferably, the thickness of the repair layer 4 obtained after curing is preferably 0.1-0.5 μm.

[0036] In some embodiments, the mass concentration of the TPU solution is 10-30%.

[0037] In some embodiments, the TPU solution further includes polyurethane elastic fibers, and the mass concentration of the polyurethane elastic fibers is 0.1-1.0%.

[0038] After verification, it was found that when polyurethane elastic fibers were added to the TPU solution, the self-repairing ability of the repair layer 4 to the insulating layer 3 could be greatly improved, making the electrical stability of the transposed conductor higher.

[0039] The cold resistance of the transposed conductor of the present invention is evaluated through some embodiments below:

[0040] It should be understood that in the following embodiments, the thickness of the insulating layers is the same and the material is also the same.

[0041] Example 1

[0042] The flat conductor is placed in an alumina ceramic vapor atmosphere for vapor deposition. During the deposition process, the side of the flat conductor is continuously turned over for uniform deposition until a 0.2 μm alumina ceramic coating is formed on the surface.

[0043] The surface of the flat conductor with alumina ceramic coating is painted with commercially available self-adhesive insulating paint, and then the flat conductor is transposed and braided to obtain the following Figure 1 Transposed conductors shown.

[0044] Example 2

[0045] 10 g of aromatic thermoplastic polyurethane particles and 90 g of tetrahydrofuran were weighed separately, mixed, stirred, and heated to 50° C. to obtain a TPU solution with a mass concentration of 10%, which was set aside.

[0046] The flat conductor is placed in an alumina ceramic vapor atmosphere for vapor deposition. During the deposition process, the side of the flat conductor is continuously turned over for uniform deposition until a 0.2 μm alumina ceramic coating is formed on the surface.

[0047] The TPU solution is coated onto the surface of the flat wire deposited with the ceramic coating, and then cured to obtain a repair layer with a thickness of about 0.2 μm.

[0048] The surface of the flat conductor with alumina ceramic coating is painted with commercially available self-adhesive insulating paint, and then the flat conductor is transposed and braided to obtain the following Figure 2 Transposed conductors shown.

[0049] Example 3

[0050] Weigh 10 g of aromatic thermoplastic polyurethane particles, 0.5 g of polyurethane fiber and 89.5 g of tetrahydrofuran respectively, mix and stir, and heat to 50° C. to obtain a TPU solution with a mass concentration of 10%, which is set aside;

[0051] The flat conductor is placed in an alumina ceramic vapor atmosphere for vapor deposition. During the deposition process, the side of the flat conductor is continuously turned over for uniform deposition until a 0.2 μm alumina ceramic coating is formed on the surface.

[0052] The TPU solution is coated onto the surface of the flat wire deposited with the ceramic coating, and then cured to obtain a repair layer with a thickness of about 0.2 μm.

[0053] The surface of the flat wire with the repair layer is painted with commercially available self-adhesive insulating paint, and then the flat wire is transposed and braided to obtain the following Figure 2 Transposed conductors shown.

[0054] Comparative Example 1

[0055] The surface of the untreated flat wire is painted with commercially available self-adhesive insulating paint, and then the wire is transposed and braided to obtain a transposed wire.

[0056] Comparative Example 2

[0057] 10 g of aromatic thermoplastic polyurethane particles and 90 g of tetrahydrofuran were weighed separately, mixed, stirred, and heated to 50° C. to obtain a TPU solution with a mass concentration of 10%, which was set aside.

[0058] The TPU solution was coated onto the surface of the untreated flat wire and then cured to obtain a repair layer with a thickness of about 0.2 μm.

[0059] The surface of the flat wire with the repair layer is painted with commercially available self-adhesive insulating paint, and then the flat wire is transposed and braided to obtain the following Figure 2 Transposed conductors shown.

[0060] The above transposed conductors were tested for eddy current loss. The transposed conductors of the same length were used in the transformers of the same model. Two groups of transposed conductors were used for each group, one of which was tested at room temperature and the other at -45°C. The test time was 720 hours. The loss ratio of the eddy current loss of the transformer at -45°C and the eddy current loss of the transformer at room temperature was calculated, and the results were shown in the following table:

[0061]

[0062] It can be seen from the data of the above embodiments that the technical solution of the present invention using a ceramic coating in combination with an insulating layer can greatly improve the cold resistance of the transposed conductor, and the degree of degradation of the electrical performance of the transposed conductor is lower than that of the conventional transposed conductor coated with only insulating paint, and the transposed conductor can effectively maintain a complete appearance. When a repair layer is used on this basis, the appearance improvement and the reduction in the loss ratio are significantly improved, especially after polyurethane elastic fibers are added to the repair layer, the loss ratio is even lower.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A cold-resistant transposed conductor, characterized in that: The invention comprises a transposed core wire, a ceramic coating, an insulating layer and a repair layer. The transposed core wire comprises a plurality of stacked and transposed flat conductors. The outer surface of the flat conductor is attached with a ceramic coating, the surface of the ceramic coating is attached with an insulating layer, the ceramic coating is made of aluminum oxide, the repair layer is attached to the surface of the ceramic coating, the insulating layer is attached to the surface of the repair layer, the repair layer is made of thermoplastic polyurethane, the preparation method of the ceramic coating comprises: placing the flat conductor in an environment containing ceramic vapor, and obtaining the ceramic coating after a period of deposition, the insulating layer is a self-adhesive insulating layer, the preparation method of the repair layer comprises: dissolving TPU particles in a solvent to obtain a TPU solution, the TPU solution also comprises polyurethane elastic fibers, the mass concentration of the polyurethane elastic fibers is 0.1-1.0%, the TPU solution is coated on the ceramic coating surface of the flat conductor, and after drying, a repair layer attached to the ceramic coating surface is obtained, and the solvent is tetrahydrofuran.

2. The cold-resistant transposed conductor according to claim 1, characterized in that: The mass concentration of the TPU solution is 10-30%.

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