JPH0354805B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing an insulated conductor using an impregnation method that leaves no resin-unimpregnated portion in an insulating layer.

[Technical background of the invention and its problems]

Conventionally, an impregnation method has been used to manufacture insulated conductors. However, since the impregnation method uses resin to fill in the gaps in an insulating layer made by winding multiple layers of insulating tape, if the resin does not reach the gaps, it will become an insulated conductor with gaps, and this insulation When windings of electrical equipment are formed using a conductor and operated, the voids tend to cause discharge deterioration, deterioration due to moisture absorption, thermal deterioration, and deterioration due to mechanical stress due to stress concentration. Therefore, in the case of the impregnation method, it is essential to reach and fill every void in the insulating layer with the resin in order to obtain a high-performance insulated conductor and ultimately an insulated coil. In particular, for high voltage coils, many layers of insulating tape, mainly made of mica tape, are wound, so in order to avoid leaving any voids in the insulating layer, it is first degassed in a vacuum impregnation tank, and then a low viscosity resin is used. Vacuum pressure impregnation involves sending the coil into the tank, immersing the coil in the resin, applying pressure to the resin for a long time, taking the coil out of the resin, and heating it to harden the resin impregnated into the insulating layer. The method is being carried out. However, even with this manufacturing method, if the insulating tape is rolled up tightly or if the adhesive in the insulating tape is somewhat sticky and the gaps between the turns of the insulating tape are stuck, unimpregnated areas may appear in the insulating layer. may remain, resulting in an insulated coil with voids and poor characteristics. Insulated conductors (including coils) with such poor characteristics are those in which an insulating layer 2 is formed by wrapping an insulating tape around a conductor 1 with a smooth surface as shown in Fig. As shown, when a conductor 1 is formed by bundling a plurality of wires 5 each having an insulation coating 4 on a core wire 3, a gap 6 is formed between the corner portions of the insulating layer 2 and the wires 5, 5. It is buried by the adhesive used to bundle the wires, or by the solder or silver solder used to connect the core wires 3 and 3 at the end of the conductor 1. The present inventor discovered that this is often seen.

Generally, the insulating layer 2 of the electrical conductor 1 is impregnated with a resin by attaching the insulating tape 7 to the insulating layer 2 as shown in FIG.
It passes through the interlayer 8, which is formed by stacking many layers of 1/2-fold wraps, and advances in the direction of arrow A from the insulating surface side. However, if the insulating layer 2 is thick, the distance required for impregnation until bending to the conductor 1 is long, and therefore the impregnation may not be completed within an economically reasonable time. Further, at the end of the insulating layer 2, the interlayers 8 of the insulating layer 2 are also impregnated as shown by arrow B. However, in this case too, if the length of the conductor is long, the impregnation cannot be completed in an economically reasonable time as before.

In general, the gap 6 formed between the corners of the insulating layer 2 and the wires 5, 5 shown in FIG. As shown by arrow C, the resin permeates along the wire 5, and the resin also penetrates through the insulating layer 2 from the wire 5 side. If this void 6 is filled with adhesive, solder, silver solder, etc., the path of impregnation along the wire 5 as indicated by arrow C is cut off, and impregnation can only occur along the paths of arrows A and B. If the conductor 1 shown in FIG. 1 without unevenness is used, there is no possibility that the path indicated by arrow C will be formed from the beginning. Therefore, insulated conductors with poor characteristics are likely to be produced when a smooth conductor is used, or when the gaps between the corners of the strands and the insulating layer are filled with adhesive, solder, silver solder, etc. Among insulated conductors, high voltage coils in particular are generally extremely expensive, and it is necessary to reduce the incidence of such defective insulated conductors to zero.

[Purpose of the invention]

An object of the present invention is to provide a method for producing an insulated conductor that can be economically impregnated with resin.

[Summary of the invention]

In the present invention, a method for producing an insulated conductor includes forming a plurality of insulating layers on an electrical conductor by winding an insulating tape, and impregnating and curing the insulating layer with a resin.
When the total number of insulation layers is N, the total number of insulation layers is 1
The conductor is divided into an integer number of inner insulating layers less than 2N/7 and an outer insulating layer of the remaining number, and is located approximately in the center of the conductor between both insulating layers, extending parallel to the conductor over the entire length in the longitudinal direction, and furthermore at both ends. The method is characterized in that the resin is impregnated and hardened by interposing an insulating spacer so that the outer insulating layer protrudes at least from the end of the outer insulating layer, and by impregnating and curing the resin from the gap created by the insulating spacer. This makes it possible to obtain a good insulated conductor without any unimpregnated parts in a short time. The reason why the insulating spacer was positioned at the above position was that the results of experiments showed that the inner and outer insulating layers were well impregnated with resin on average, and that placing the insulating spacer directly on the conductor This is to avoid the fact that the insulating layer is likely to peel off from the conductor, and if peeling occurs directly above the conductor where the electric field is highest, deterioration is likely to progress.

[Embodiments of the invention]

Example 1 A first example of the present invention will be described below with reference to FIGS. 4 and 5. This example shows an insulated conductor for connecting an insulated coil of a rotating electric machine.
The electrical conductor 1 has a rectangular cross section with no irregularities on its surface, and has a thickness of
An insulating tape of 0.24 mm and width 32 mm consisting of a glass woven reinforced mica tape having 7 to 15% by weight of epoxy resin as an adhesive is wound five times in a 1/2 fold, that is, five inner insulating layers 9 are formed. Form. A 1 mm thick, wide
A 40 mm glass woven tape is bonded with an adhesive as a spacer 10, and both ends of the spacer 10 are made to protrude from the ends of the inner insulating layer 9. The same insulating tape used for the inner insulating layer 9 is wrapped 1/2 times around its outer circumference.
The outer insulating layer 11 was wound 25 times, that is, 25 layers of the outer insulating layer 11 were formed. Therefore, the total number of layers N of the insulating layer 2 is 30 (N=5+25=30). In this case, it goes without saying that both ends of the spacer 10 should protrude from the ends of the outer insulating layer 11. Thereafter, the insulated conductor is placed in a vacuum impregnation tank, the pressure is reduced to 0.5 Torr or less, and 1 poise epoxy resin is fed into the tank, the conductor is immersed in the resin, and 7Kg/cm ² G is applied. The resin was pressurized for a predetermined period of time. Incidentally, this predetermined time is determined by wrapping a wire mesh tape (not shown) around the center of the outermost periphery of the insulating layer 2 of the insulated conductor, and measuring the change in capacitance between the conductor 1 and the wire mesh using the resin pressurization time. It is measured as the time taken to reach saturation as shown by curve a in FIG. 6. The conductor whose insulating layer 2 has been impregnated with resin in this manner is taken out from the vacuum impregnation tank, a steel plate is placed around it, a heat shrink tube is wound around it, and the insulated conductor is cured by heating.

Next, the effect will be explained.

When the insulating spacer 10 is not used, the insulating layer 2
Wrap wire mesh tape around the center of the outermost circumference of conductor 1.
The change in capacitance between the wire mesh and the wire mesh was measured with respect to the resin pressurization time, and the time required to reach saturation was found to be several times that of curve a in this example, as shown in curve b in Figure 6. It takes time. Therefore, according to the manufacturing method of this example, the resin can be reliably impregnated in a short period of time.
The economic value is clear. The reason why the inner insulating layer 9 has 5 layers and the outer insulating layer 11 has 25 layers is as follows.

That is, when the impregnation test was repeated by varying the position of the spacer 10 and the number of layers of insulating tape,
In FIG. 7, the ratio of the number of layers accessible by impregnation from the direction of arrow D to the number of layers accessible from the direction of arrow D was 4:3. Therefore, if the total number of layers N is 10, four layers are impregnated from the outermost periphery in the direction of arrow A at the same time, and the passage 12 on the side surface of the spacer 10 is impregnated in the direction of arrow A.
(See Fig. 5) Three layers are impregnated from the outside and inside in the direction of arrow D. Therefore, spacer 1
It has been found that the resin impregnation of the inner portions of the inner insulating layer 9 and the outer insulating layer 11 can be reliably carried out if the number 0 is set to 3N/10 layers or less from the inside. However, when impregnating the entire insulating layer 2, it is necessary to ensure that the inside is more impregnated than the outside in order to prevent deterioration due to high electric fields on the inside.
The condition is that it is 2N/7 or less, which is slightly smaller than 3N/10. Furthermore, if the spacer 10 is provided directly on the conductor 1, the insulating layer 2 will easily peel off from the conductor 1 due to thermal stress due to the difference in thermal expansion coefficient with the conductor 1, and the insulation layer 2 will peel off directly above the conductor where the electric field is highest. If this occurs, the insulating layer 2 is likely to deteriorate, so at least one inner insulating layer 9 must be provided.

In Example 1 above, the total number of insulating layers N=30, so 2N/7=2×30/7≒8.6, and it is necessary to take an integer and make 8 layers or 1 layer the inner insulating layer 9. It is appropriate to have five layers.

Further, the reason why the insulating spacer 10 is arranged approximately at the center of the conductor 1 in the width direction is that the electric field is highest at the corners of the conductor and is easily deteriorated. In general, the width of the insulating spacer 10 is 3/5 or less of the width of the conductor 1, preferably about half, which is good in terms of impregnability and deterioration resistance.

In addition, in FIG. 5, the arrangement of the insulating spacers 10 is as follows.
Although the conductor 1 is shown as being provided only on the two wide sides, it may be provided on four sides including the two narrow sides.
Further, the insulating spacer 10 does not need to protrude from the end of the inner insulating layer 9, but only needs to protrude from at least the end of the outer insulating layer 11.

Example 2 The second example shown in FIGS. 8 and 9 is an insulated conductor as a half coil for a turbine generator. A conductor 1 is formed by bundling eight strands 5 each having a water passage hole 13 in the core wire 3 and an insulating coating 4 provided thereon. 6 are buried in H portions near both ends of the conductor 1 by flowing silver solder during silver soldering between the clip 14 of the water pipe and the core wire 3. Therefore, Example 1
Four layers of inner insulating layer 9 are formed by wrapping the same insulating tape 1/2 times four times, and part of the layer at the end is wound up to above the clip 14. Wide width of conductor 1 (68
mm) The same thickness as the insulating tape described in Example 1 is 0.24mm so that it is located approximately in the center of the conductor 1 on the surface side.
Four pieces of mica tape with a width of 32 mm and a width of 32 mm are stacked and arranged as an insulating spacer 10, and both ends of the mica tape are
Let it extend to the top of 4. Twenty layers of the outer insulating layer 11 were formed around the outer periphery by wrapping the same insulating tape as the inner insulating layer 9 1/2 times 20 times. Similarly to the first embodiment, both ends of the insulating spacer 10 protrude from both ends of the outer insulating layer 11. Next, in the same manner as in Example 1, an epoxy resin is impregnated with vacuum pressure and cured by heating to obtain an insulated conductor for a half coil.
Then, an insulating tape is further wound over the clip 14 to form a protective insulation 15.

Next, the effect will be explained.

The total number of insulating layers N is N=4+20=24. Therefore, since 2N/7=2×24/7≒6.85, the fact that the inner insulating layer 9 has four layers is 1
and 6, which is appropriate. FIG. 10 shows a comparison of the Δtanδ cumulative frequency distribution characteristics of the thus obtained insulated conductor and the insulated conductor manufactured by the conventional method without an insulated spacer. Δtanδ is the difference between Δtanδ at the rated voltage and tanδ at (rated voltage −2 kV). It was found that the curve a representing the present example had a smaller Δtanδ and less fluctuation than the curve b representing the conventional one. This is because the insulating spacer 10 forms a passage 12 in which the resin is impregnated, and the resin passes through this passage 12 and is impregnated with the resin, so that the resin can be completely impregnated within an economically reasonable amount of time. .

In the present invention, in addition to mica tape, the insulating spacer 10 may be made of polyester or aramid nonwoven felt, glass woven tape, glass rope, or glass aramid board (there is also a product named GA board by Nippon Aroma Co., Ltd.). A laminate plate or the like may be used, which is compressed during molding and curing after being impregnated with resin, and is covered with an inner and outer insulating layer 9 by insulating tape 7.
Mica tape, non-woven felt, etc. that are integrated with 11 are suitable. Moreover, as the insulating tape 7,
Mica tape, films such as polyester and polyamide, non-woven tapes such as polyester and aramid, and aramid paper can be used. For high voltage insulation, both the insulating spacer 10 and the insulating tape 7 are preferably mica tapes, which have excellent partial discharge resistance. As the resin, solvent-free thermosetting resins such as epoxy, polyimide, and polyester are preferred.

〔Effect of the invention〕

As explained above, according to the present invention, the total number of insulating layers N is divided into an integer number of 1 or more but less than 2N/7 inner insulating layers and the remaining number of outer insulating layers, and a conductor is formed between the two insulating layers. An insulating spacer is placed almost in the center, parallel to the conductor, extending over the entire length in the longitudinal direction, and further protruding from at least the ends of the outer insulating layer, so that the resin can be impregnated and hardened. In addition, since the resin impregnates the inner and outer insulation layers through the passages formed on both sides of the insulation spacer, the insulation layer can be completely impregnated with the resin in an economically reasonable time. In addition, since the insulating spacer is located not directly above the conductor, but between the inner and outer insulating layers, and approximately at the center of the conductor width, the presence of the insulating spacer may cause electrical deterioration, mechanical stress deterioration, etc. to the insulating layer. This is a method of manufacturing highly transparent insulated conductors that does not have any adverse effects.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional views of insulated conductors manufactured using different conventional methods, and Figure 3 is a cross-sectional view of an insulated conductor manufactured using different conventional methods.
FIG. 4 is a plan view of an insulated conductor showing a state in the middle of manufacture in the first embodiment of the method of the present invention, and FIG. FIG. 6 is an enlarged sectional view taken along the line, FIG. 6 is a curve diagram showing a comparison of changes in capacitance with respect to resin impregnation time of insulated conductors manufactured by the method of the first embodiment and the conventional method, and FIG. The figure is an explanatory diagram showing the path of resin impregnation in the insulating layer of the first embodiment, FIG. 8 is a plan view of the insulated conductor of the second embodiment showing a state in the middle of manufacturing, and FIG. 9 is the − of FIG. 8. FIG. 10, which is an enlarged cross-sectional view taken along the line, is a curve diagram showing a comparison of the cumulative frequency distribution of Δtanδ of insulated conductors manufactured by the method of the second embodiment and the conventional method. DESCRIPTION OF SYMBOLS 1...Conductor, 2...Insulating layer, 7...Insulating tape, 9...
Inner insulating layer, 10... Insulating spacer, 11... Outer insulating layer.

Claims (1)

[Scope of Claims] 1. A method for manufacturing an insulated conductor in which a plurality of insulating layers are formed on an electrical conductor by winding an insulating tape, and the insulating layer is impregnated with a resin and cured, when the total number of insulating layers is N, The total number of insulation layers is divided into an integer number of 1 or more and less than 2N/7 inner insulation layers and the remaining number of outer insulation layers, and the layer is located approximately in the center of the conductor between the two insulation layers, and is parallel to the conductor. A method for manufacturing an insulated conductor, which comprises impregnating and curing a resin with an insulating spacer interposed so that it spans the entire length in the longitudinal direction and further protrudes from at least the ends of the outer insulating layer. 2. The method for manufacturing an insulated conductor according to claim 1, wherein the width of the insulating spacer is 3/5 or less of the width of the conductor. 3. The method for manufacturing an insulated conductor according to claim 1 or 2, wherein the insulating spacer uses mica tape.