JPH0458415A - Manufacture of heat-resistant insulated coil - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant insulated coil for high voltage which is able to be used for a long duration stably at high temperature and is not deteriorated by heating cycles by coiling up a mica tape prepared by sticking an inorganic reinforcing material with an adhesive of an inorganic silicone or an inorganic paint while applying an inorganic silicone or inorganic paint to a conductor and firing them and making them inorganic. CONSTITUTION:A conductor 1 is composed of a flat square wire of copper 2 reinforced by dispersion of nickel-coated alumina and a mica tape 3 consisting of a silica cloth and a soft and not sintered collecting mica sheet stuck to the cloth with a small amount of silicone adhesive and being coiled on the copper. After the conductor 1 is coiled up into a pancake-like shape, it is shaped using an inorganic adhesive 4 such as an alkyl silicate-based inorganic silicone containing an inorganic filler, alumina, etc. Further a mica tape 5 composed of an inorganic filler-containing inorganic silicone and a pressure-sensitive silicone adhesive applied to the inorganic silicone is coiled on the conductor and the resulting product is fired at >=300 deg.C to make it inorganic and then an inorganic insulating tape bearing no adhesive 6 is coiled on the obtained conductor to give a heatresistant insulated coil.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention provides 1
! The present invention relates to a method for manufacturing heat-resistant insulated coils for electrical equipment used at high temperatures of 300°C or higher, such as electromagnetic pumps for rings.

(Prior technology) Heat-resistant insulated wire rings that can be used at high temperatures of 300°C or higher are little known, such as the MI cable (product of Furukawa Electric Co., Ltd.), which uses magnesium oxide powder between the conductor and the metal sheath. Filled heat-resistant insulated wires are known, but because they have a metal sheath, eddy current countermeasures are required, and the conductor space factor is low, so they are not suitable for wire rings in large-capacity electrical equipment. It was not suitable.

In addition, Special Publication No. 62-1241 and Special Publication No. 62-12
No. 42 discloses that silicone resin or
Filled with silicone resin and high melting point inorganic powder and/or
Alternatively, a heat-resistant insulated coil characterized in that an inorganic layer is formed by coating and firing is described.

In addition, Japanese Patent Publication No. 62-57086 and Special Publication No.
Publication No. 57087 describes a method for manufacturing a heat-resistant insulated coil device in which a coil is wrapped with an inorganic insulating layer on a conductor or a heat-resistant insulated wire that turns into an inorganic substance at high temperatures such as during abnormal phase use and fixed. has been done.

(Problem to be Solved by the Invention) The heat-resistant insulated wire wheels described in these known examples have a powdery inorganic layer formed on the surface, so when used for a long period of time, the powdery inorganic layer becomes exposed. The layer gradually turns into powder, falls off, and disintegrates, so it cannot be used stably for a long period of time. In addition, since a very thick inorganic layer cannot be formed, the dielectric breakdown voltage is low and it cannot be used for high voltage equipment. In the case of high-voltage equipment like this, mica tape or insulating tape is heated and pressed using an inorganic polymer (polymer that can be made inorganic) or an inorganic adhesive to form it, and then baked to form completely inorganic insulation. is possible.

However, insulation that is entirely glued together like this.

During startup and shutdown, thermal stress is generated due to the difference in thermal expansion coefficient between the conductor and the insulating layer, and when this heat cycle is repeated, cracks occur in the insulation due to fatigue, resulting in a decrease in insulation. This phenomenon is particularly likely to occur in large windings for large-capacity machines and in equipment used at higher temperatures.

Therefore, for the circulation of liquid sodium in fast breeder reactors,
300 such as liquid sodium immersion type non-cooled electromagnetic pump, etc.
Insulated wire rings used at high temperatures of 300°C or higher must have high heat resistance so that they can be used stably for long periods of time at high temperatures of 300°C or higher. There is a need to reduce the external size of electromagnetic pumps.

Large-capacity machines require high-voltage insulated wire rings that do not deteriorate due to heat cycles.

The present invention was made in response to these demands, and can be used stably for a long period of time at high temperatures of 300°C or higher.
It is an object of the present invention to provide a method for manufacturing a heat-resistant insulated wire ring that can be used even at high voltages without causing insulation deterioration due to heat cycles.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a mica tape in which a conductor is coated with inorganic silicone or inorganic paint, and an inorganic reinforcing material is bonded to the conductor using an adhesive made of inorganic silicone or inorganic paint. After winding and inorganicizing the wire by firing at a temperature of 300°C or higher, a heat-resistant insulated wire ring is manufactured by winding an inorganic insulating tape with high mechanical strength, excellent heat resistance, and no adhesive on top of this. It is something.

An inorganic filler may be added to the above-mentioned inorganic silicone or inorganic paint.

Here, as the inorganic filler, alumina (xx20
3), magnesia (MgO), silica (S10□), zirconia (ZrO2), steatite (MgSiO3
) Includes clay kaolin, mica powder, high melting point glass frit, etc. The average particle size of these fillers is 1
The time is preferably 0 μs or less.

Inorganic silicone is a general term for silicones that become mineralized by firing at high temperatures.

For example, alkyl silicate silicone AY49-2
08 (trade name of Toshiba Silicone Co., Ltd.), inorganic filler borosiloxane paint S M R-109 (trade name of Showa Denshin Co., Ltd.), and pressure-sensitive adhesive YR3286 (trade name of Toshiba Silicone Co., Ltd.) made of methylpolysiloxane. name) etc.

Furthermore, inorganic paints include phosphates such as aluminum monophosphate and silicon phosphate, colloidal silica, and colloidal alumina.

If a large amount of inorganic filler is added to the inorganized silicone, it will generally become more thermally stable and will be cheaper. However, since the filler itself does not bond by firing, it is necessary to blend inorganic silicone to the extent that it forms a strong bond by firing.

On the other hand, the combination of inorganic filler and inorganic silicone
It is necessary to select a material that is not difficult to apply and does not become brittle after firing. Usually, the inorganic filler content is 1
It is preferably about 0 to 90% by weight.

In addition, heat-resistant materials such as alumina, alumina-boria-silica (for example, 3M's product name Nextel), and silica are used as reinforcing materials for mica tape and heat-resistant inorganic insulating tapes that do not have adhesives. Use woven or non-woven fabric made from fibers with high mechanical strength. In the case of woven fabric, it is preferable that the fabric be woven with high fiber density in order to improve the thermal conductivity of the insulating layer. In general, for mica tape reinforcing materials, tapes with a thickness of about 30 to 400 mm are advantageous in terms of insulation design because they increase the space factor of the mica layer and provide a large dielectric breakdown voltage per unit thickness. Inorganic insulating tape, which has high mechanical strength and excellent heat resistance and does not contain adhesive, requires mechanical strength, so 1.
A relatively thick tape of about 00 to 500 ρ is suitable.

In addition, alumina is used to prevent the end of the insulating tape from loosening.

It is pressed and wrapped with a thread made of inorganic fibers such as alumina, polysilica, silica, or the ends of the insulating tape are coated with the above-mentioned inorganic silicone or inorganic paint, and then bonded by high-temperature baking treatment.

(Function) The mica tape is used here because mica has high heat resistance and is also excellent in dielectric breakdown voltage and voltage resistance. The reason why mica tape was used near the conductor is that the electric field is higher near the conductor, and by placing a material with high voltage resistance, the life can be extended.

Mica tape has excellent electrical properties but is slightly inferior in mechanical strength, so it can be made by wrapping a heat-resistant inorganic insulating tape with high mechanical strength over the mica tape, which has poor mechanical strength, and pressing it down. This can prevent the mica tape from falling apart.

Wrapping and firing mica tape while applying inorganic silicone containing an inorganic filler or inorganic paint is as follows.
This is because a strong insulating layer can be formed by adhering the conductor and the mica tape and the mica tapes to each other.

Since mica has excellent interfold properties, the thermal stress caused by the heat cycle associated with the operation and shutdown of equipment is absorbed by the displacement of the mica layer. Therefore, the inorganic silicone or inorganic paint is baked and solidified to prevent cracks from occurring.

On the other hand, since the inorganic insulating tape wound on the surface is not coated with adhesive, it absorbs thermal stress caused by heat cycles by deforming itself. Therefore, the insulating tape will not be cut. However, when an insulating tape without an adhesive is wound around the surface in this way, the insulating tape becomes loose, so a loosening prevention measure as described above is required.

In the present invention, after winding a mica tape made by bonding an inorganic reinforcing material with an adhesive made of inorganic silicone or an inorganic paint, the process of inorganicizing it by baking it at a temperature of 300° C. or higher is as follows. Volatile components generated when baking the mica tape adhesive and the inorganic silicone or inorganic paint applied when winding the mica tape at a high temperature of 300"C or higher increase the mechanical strength of the mica tape that is wound over it. This is because if it adheres to an inorganic insulating tape that has excellent heat resistance and does not have an adhesive, the mechanical strength of the inorganic insulating tape will be significantly reduced.

In addition, in the heat-resistant insulated wire of the present invention, the operating temperature is 30
When used at a high temperature of about 0° C., soft mica is better than hard mica.

This is because hard mica has a lower crystal water release temperature and lower heat resistance than soft mica. Figure 3 shows an example of the life test results of energizing at 1.5 kV/mm at high temperatures on the edges of mica windings. Hard mica tape-wound insulation A is more energized at high temperatures than hard mica-wound insulation B. It can be seen that the life characteristics are excellent.

Furthermore, the conductor used in the present invention may be a conductor itself without insulation coating, or may be an insulated wire with insulation coating.

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

Example 1 In FIG. 1, a conductor 1 is made of nickel-plated alumina dispersion-strengthened copper 2 (product name: Gρid, manufactured by Gliden Metal Co., Ltd.).
copA L-15) with a thickness of 507
A mica tape 3 is wound around the silica cloth (a) and a soft unfired laminated mica sheet with a thickness of 100 mm and a small amount of silicone (for example, Toshiba Silicone Co., Ltd.'s product name YR3286) is used as an adhesive. This conductor 1,
Inner diameter 400mm, outer diameter goo+mm.

After rolling it into a pancake shape to a thickness of 40 mm, apply an inorganic adhesive such as alkyl silicate-based inorganic silicone containing an inorganic filler (trade name AY49-208 of Toshi Silicone Co., Ltd.) or alumina. Use to mold. Furthermore, on top of this, a 50μs thick alumina woven fabric was added to a thickness of 10μs.
0tIn unfired soft laminated mica is backed and reinforced, and inorganized silicone containing the above-mentioned inorganic filler (trade name AY49-208 of Toshi Silicone Co., Ltd.) and an inorganic filler polysiloxane resin paint (Showa Cable Electric Wire) are used. Company product name S
A mica tape 5 made by applying M R-1069) and a silicone pressure-sensitive adhesive (trade name YR3286 of Toshiba Silicone Co., Ltd.) is coated with inorganic silicone containing the above-mentioned inorganic filler (trade name A Y of Toshiba Silicone Co., Ltd.). 49-208)
It was wound three times with 172 layers while applying the same amount. Wrap polytetrafluoroethylene tape (not shown) for mold release on the outside of the mold, apply a steel plate to it, then wrap heat-shrinkable polyester tape (which may be in the form of a film, tube, or woven fabric). was cured by heating at 80°C for 1 hour, 130°C for 2 hours, 150°C for 2 hours, and further at 180°C for 15 hours. After that, the heat-shrinkable polyester tape, the iron plate, and the polytetrafluoroethylene tape for type A were removed, and the wire was fired in air at 300°C for 8 hours and at 600°C for 8 hours to form a heat-resistant insulated wire. I got it.

In the above manufacturing process, the pressure applied during heat curing is performed by heat shrinking the heat shrinkable polyester tape, and the organic components contained in the insulating layer are scattered and burned away by heating and baking at high temperatures, becoming inorganic ( (ceramic), and a completely inorganic insulating layer was formed. Furthermore, a 300-thick insulating tape 6 made of an alumina fiber woven fabric without an adhesive was wound once as an inorganic insulating tape without an adhesive over this in a 1/2 overlap. Thereafter, an insulating layer was formed by winding the insulating tape while pressing a thread made of alumina fiber onto the wound end of the insulating tape so that the end of the insulating tape did not come loose.

On the other hand, as Comparative Example 1, after wrapping the mica tape 4 according to the above-mentioned Example 1, an inorganic insulating tape without adhesive was applied on top of the mica tape 4 using alumina fiber woven fabric without adhesive with a thickness of 300 mm. Insulating tape 6 consisting of 1/2
It was wound once in layers.

Thereafter, in order to prevent the ends of the insulating tape from loosening, threads made of alumina fibers were pressed onto the ends of the insulating tape and wound to form an insulating layer.

As Comparative Example 2, after wrapping the mica tape 4 in accordance with Example 1 described above, an inorganic insulating tape without the adhesive was coated with inorganic silicone (Togashi) containing the inorganic filler. Silicone company product name AY
49-208) and an inorganic filler borosiloxane-based resin paint (trade name SMR-109 of Showa Denshin Co., Ltd.) is applied and dried, and a prepreg-like insulating tape is coated with inorganic silicone (49-208) containing an inorganic filler. While applying AY49-208 (trade name, manufactured by Toshi Silicone Co., Ltd.), the above-mentioned mica tape 4 was wound once with a 1/2 overlap to form an insulating layer.

After that, in both Comparative Examples 1 and 2, polytetrafluoroethylene tape (not shown) for mold release was wrapped around the outside of the insulating layer thus formed, and an iron plate was applied, as in Example 1 described above. After that, wrap a heat-shrinkable polyester tape (which may be in the form of a film, tube, or woven fabric) and heat it at 80°C for 1 hour, then at 30°C for 2 hours at 150°C.
It was cured by heating at 180°C for 2 hours and then at 180°C for 15 hours. After that, the heat-shrinkable polyester tape, the iron plate, and the polytetrafluoroethylene tape for mold release were removed, and the wire was fired in air at 300°C for 8 hours and at 600°C for 8 hours, and the heat-resistant insulated wire was I got a ring.

Example 2 In place of the conductor in Example 1, as shown in FIG. 2, a conductor 1 was made of alumina dispersion-strengthened copper 5 (trade name of Glidden Metal Co., Ltd.) with a circular cross-section diameter 1 and 3 mm plated with nickel to a thickness of 5 μs. A round wire made of G12id copA L-15) is wound with a yarn of high-temperature ceramic fiber 7 (trade name: Nextel, manufactured by 3M Corporation in the United States) made of three components: alumina, boria, and silica, and then an inorganic-filled split boro is wound on top of the yarn. A heat-resistant insulated wire 9 is coated with a siloxane-based resin paint 8 (product name SMR-109 of Showa Denshin Co., Ltd.) and baked at 485°C to form a baked coating of insulating paint, and then coated with an inorganic filler. Mineralized silicone containing 10 (
The material was coated with Toshi Silicone Co., Ltd. (trade name: AY 49-208) and then heated and rolled in multiple layers.

Thereafter, a heat-resistant insulated coil was manufactured in the same manner as in Example 1.

When the heat-resistant insulated coils obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were heat cycled 1000 times between room temperature and 650°C, Comparative Example 2 was the fastest, and the alumina woven tape with an insulating surface Cracks occurred and the alumina fibers were cut. As the number of heat cycles increased, this crack spread over the entire surface of the insulating layer, and the crack itself also expanded.

Next, in Comparative Example 1, cracks occurred in the alumina woven tape on the insulating surface, but compared to Comparative Example 2, the number and size of the cracks were smaller. Compared to these, this example 1゜2
In this case, no cracks were observed even after 1000 heat cycles. heat cycle 100
The remaining dielectric breakdown voltage after 0 cycles (percentage of dielectric breakdown voltage after heat cycle deterioration with respect to the initial value of dielectric breakdown voltage) was 93% in Example 1.

89% in Example 2, 78% in Comparative Example 1, 55% in Comparative Example 2
%, the residual dielectric breakdown voltage of the insulated coil of the present invention was high.

The reason why the comparison example deteriorated more than the example due to the heat cycle test is that Table 1 shows the tensile strength of the alumina tape portion of the insulating surface cut out from the insulated wire ring before the heat cycle test and before taping. This can be said to be because the alumina tape of the comparative example has a significantly lower tensile strength than that of the present invention, as shown as a relative value to the tensile strength of the tape. The reason why the tensile strength was low in Comparative Example 1 is that when the inorganic silicone in the mica tape layer is sintered, volatile components adhere to the alumina fibers and are sintered, reducing the strength of the fibers.

Table 1 Tensile strength of the alumina tape portion on the insulating surface of the insulated wire (relative value to the tensile strength of the tape before taping) Note that the heat-resistant insulated wire obtained in Examples 1 and 2 was filled with nitrogen. Although it was heated in an atmosphere of 600° C. for one year, the breakdown voltage after heating was all 90% or more of the initial value.

〔Effect of the invention〕

As explained above, according to the present invention, a mica tape made by applying inorganic silicone or inorganic paint to a conductor and pasting an inorganic reinforcing material with an adhesive made of inorganic silicone or inorganic paint is wound around the conductor. After baking at a temperature of 300°C or more to inorganicize and form a mica tape with excellent electrical properties and heat resistance on the inner layer in contact with the conductor, a mica tape with high mechanical strength and excellent heat resistance is placed on top of this. Since the inorganic insulating tape without adhesive is wound, a heat-resistant insulated wire ring with excellent electrical and mechanical properties can be obtained. In addition, this heat-resistant insulated wire ring has almost no deterioration in performance even when used continuously at high temperatures, and the insulation layer will not crack even if the heat cycle that occurs when equipment starts and stops is repeated. , there is almost no deterioration in insulation performance. Therefore, it is possible to provide a public manufacturing method for heat-resistant insulated wires used at high temperatures of 300° C. or higher, such as electromagnetic pumps for circulating liquid sodium in fast breeder reactors.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a heat-resistant insulated wire ring showing one embodiment of the present invention, Fig. 2 is a cross-sectional view of a heat-resistant insulated wire ring showing another embodiment of the present invention, and Fig. 3 is a cross-sectional view of a heat-resistant insulated wire ring showing another embodiment of the present invention. FIG. 3 is a comparison diagram of the electrical life characteristics of insulation and hard mica tape-wrapped insulation at high temperatures. 1. Conductor 2... Nickel plated alumina dispersion strengthened copper 3.
5... Mica tape 4... Mineralized silicone or inorganic adhesive 6... Inorganic insulation tape without adhesive 7... High temperature ceramic fiber

Claims (2)

[Claims] (1) While applying inorganic silicone or inorganic paint to the conductor, wrap a mica tape made by bonding an inorganic reinforcing material with an adhesive made of inorganic silicone or inorganic paint, and bake at a temperature of 300°C or higher. After mineralization,
A method for manufacturing a heat-resistant insulated wire, comprising winding an inorganic insulating tape having high mechanical strength, excellent heat resistance, and no adhesive on the wire. (2) The method for producing a heat-resistant insulated wire according to claim 1, wherein the inorganic silicone or the inorganic paint contains an inorganic filler.