JPH04245404A - Manufacture of heat-resistant insulated coil - Google Patents

Abstract

PURPOSE:To provide the manufacturing method of a heat-resistant insulated coil which can be used stably for a long time even at a high temperature of especially 300 deg.C or higher, whose insulation is not deteriorated by a heat cycle and whose withstand-voltage characteristic is excellent at the insulated coil for an apparatus which is used at a high temperature such as a non-cooling electromagnetic pump of liquid sodium immersion type. CONSTITUTION:A heat-resistant insulated coil by this invention is manufactured as follows: mica sheets formed by pasting inorganic reinforcement materials by using an inorganic adhesive are worked to be strip-shaped; while they are being overlapped, they wrap a conductor; an inorganic insulating tape whose mechanical strength is large, whose heat-resistant property is excellent and which does not contain an adhesive is wound on them; and, after that, this assembly is baked at a high temperature of 300 deg.C or higher.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

[Industrial Application Field] The present invention is applicable to electromagnetic pumps for circulating liquid sodium in fast breeder reactors.
The present invention relates to a method for manufacturing heat-resistant insulated coils for electrical equipment used at high temperatures of 0° C. or higher.

0002

2. Description of the Related Art Heat-resistant insulated coils that can be used at high temperatures of 300° C. or higher are hardly known. Heat-resistant insulated wires such as MI cable (product name of Furukawa Electric Co., Ltd.), which are filled with magnesium oxide powder between the conductor and the metal sheath, are known; Therefore, countermeasures against eddy currents are required, and the conductor space factor becomes low, making it unsuitable for wires of large-capacity electrical equipment.

Furthermore, in Japanese Patent Publication No. 62-1241 and Japanese Patent Publication No. 62-1242, silicone resin or its silicone is used in at least a part of the inter-wire gap and the outer surface of the coil. A heat-resistant insulated coil is described in which an inorganic layer is formed by filling and/or coating a resin and a high-melting-point inorganic powder and then firing the coil.

Furthermore, Japanese Patent Publication No. 62-57086 and Japanese Patent Publication No. 62-57087 disclose a process in which an inorganic insulating layer is wrapped around a conductor, or a heat-resistant insulated wire that turns into an inorganic substance at high temperatures such as abnormalities during use is wrapped around the conductor. A method for manufacturing a heat-resistant insulated coil device for fixing a coil is described.

[0005]

[Problems to be Solved by the Invention] The heat-resistant insulated wire wheels described in these known examples have a low dielectric breakdown voltage because they cannot form a very thick inorganic layer and the insulating layer itself is rough, and are not suitable for high voltage applications. The drawback was that it could not be used for equipment. Therefore, in the case of high-voltage equipment, glass mica tape using an inorganic polymer (a polymer that can be turned into an inorganic substance at high temperatures) adhesive is wound as the main insulation, and this is heated and pressurized to form the material and then fired. , a method of forming completely mineralized insulation is considered.

[0006] However, with insulation that is entirely fixed with adhesive, thermal stress is generated due to the difference in thermal expansion coefficient between the conductor and the insulation layer when the equipment is started or stopped, and this heat cycle is repeated. When this happens, cracks occur in the insulation due to fatigue.
Insulation performance deteriorates. This phenomenon is particularly likely to occur in large windings for large-capacity machines and in equipment operated at higher temperatures.

[0007] Therefore, insulated wire rings used at high temperatures of 300°C or higher, such as liquid sodium submerged uncooled electromagnetic pumps used in fast breeder reactors, must have high heat resistance so that they can be used stably for long periods of time at high temperatures. . Large-capacity machines require high-voltage insulated wire rings that do not deteriorate due to heat cycles.

[0008] The present invention was made in response to these demands, and is capable of being used stably for a long period of time at high temperatures of 300°C or higher, and can also be used at high voltages without deteriorating insulation performance due to heat cycles. The purpose of the present invention is to provide a heat-resistant insulated wire ring that can be used. [Structure of the invention]

[0009]

[Means for Solving the Problems] The present invention involves processing a mica sheet made of an inorganic reinforcing material laminated with an inorganic adhesive into a strip shape, wrapping the conductor while overlapping each other, and mechanically applying After winding an inorganic insulating tape with high strength, excellent heat resistance, and no adhesive, the tape is fired at a high temperature of 300°C or higher to produce a heat-resistant insulated coil.

[0010] Here, as the inorganic adhesive, there is an inorganic silicone which becomes inorganic by firing at a high temperature. For example, alkyl silicate silicone AY49
-208 (trade name of Toray Silicone Co., Ltd.), borosiloxane paint with inorganic filler SMR-109 (trade name of Showa Denshin Co., Ltd.), etc. Furthermore, aluminum monophosphate, colloidal silica, colloidal alumina, etc. are included.

[0011] In addition, as reinforcing materials for mica sheets and inorganic insulating tapes that do not have adhesives, alumina, alumina-boria-silica (for example, the product name of 3M Corporation in the United States is Nextel), silica, etc. Use woven or non-woven fabric made from fibers that are heat resistant and have high mechanical strength.

[0012] There are two methods for wrapping the conductor while overlapping strip-shaped mica sheets: one is to use flexible mica sheets, and the other is to form the mica sheets into a conductor shape in advance and then overlap them. be. Furthermore, we are not limited to mica sheet molded products, but also alumina (Al2O3), silicon nitride (silica), which have excellent mechanical and electrical strength at high temperatures.
There are ceramic molded products such as Si3N4).

[0013] To prevent the terminals of the insulating tape from loosening, it is necessary to wrap them with a thread made of inorganic fibers such as alumina, alumina/boria/silica, or silica, or apply the above-mentioned inorganic adhesive to only the terminals of the insulating tape. It is applied and bonded using a high temperature firing process.

[0014]

[Operation] Mica sheet is used here because mica has high heat resistance and excellent dielectric breakdown voltage and withstand voltage characteristics.

Mica sheet has excellent electrical properties but is slightly inferior in mechanical strength, so a heat-resistant inorganic insulating tape with high mechanical strength is placed over mica tape, which has poor mechanical strength. By winding and pressing the
This can prevent the pieces from falling apart.

[0016] Rather than continuously wrapping the mica sheet, the conductor was insulated by folding the mica sheet in strips, so that the conductor was insulated due to the difference in thermal expansion between the conductor and the insulator during heat cycle operation of the equipment. Thermal stress can be absorbed by the easy displacement between mica sheets and damage to the insulation can be prevented.

On the other hand, since the inorganic insulating tape wound on the surface is not coated with adhesive, it absorbs the thermal stress caused by the heat cycle by deforming itself. Therefore, the insulating tape will not be cut. However, if the insulating tape without adhesive is wound on the surface in this way, the insulating tape will loosen, so it will be necessary to prevent it from loosening as described above. In addition, high-voltage insulation that requires a thick insulation layer can be easily produced by alternately folding strips of mica sheets and wrapping and pressing them with insulating tape.

[0018]

[Example] Example 1

In FIG. 1, the conductor 1 is a rectangular wire made of nickel-plated alumina dispersion-strengthened copper 2 (product name: Glid copAL-15, manufactured by Glidden Metal Co., Ltd.), with a 50 μm thick silica cloth and a 100 μm thick unfired wire. The conductor 1 is wound with a mica tape 3 made by laminating a soft laminated mica sheet with a small amount of silicone (for example, Toshiba Silicone Co., Ltd.'s product name YR3286) as an adhesive. Outer diameter 900mm, thickness 40m
After rolling it into a pancake shape,
It is molded using an inorganic adhesive 4 such as AY49-208 (trade name, manufactured by Toray Silicone Co., Ltd.). Furthermore, alumina cloth with a thickness of 50 μm is placed on top of this to a thickness of 100 μm.
Reinforced with m unfired laminated mica, and inorganized silicone
(Toray Silicone Co., Ltd.'s product name AY49-208) and silicone pressure-sensitive adhesive (Toshiba Silicone Co., Ltd.'s product name YR)
Mica sheet 5 made by applying 30% by weight of
was applied using the method described below. The mica sheet 5a cut into strips is made into a U-shape and wrapped around the conductor. Next, the rectangular mica sheet 5b is formed into a U-shape so that the ends of the mica sheet 5a overlap, and the conductor is wrapped around it. In this way,
The pancake-shaped conductor was also wrapped in a mica sheet so that it overlapped by 1/2 in the circumferential direction. moreover,
As an inorganic insulating tape 6 without adhesive, an insulating tape 7 made of alumina fiber cloth having a thickness of 300 μm was wound once on this in a 1/2 wrap. Subsequently, inorganic silicone (trade name AY49-208, manufactured by Toray Silicone Co., Ltd.) was applied to form a stopper insulating layer so that the end of the insulating tape would not come loose.

On the other hand, as a comparative example, instead of the mica sheet of Example 1, a mica tape having the same composition as the mica sheet was manufactured, and a mica tape made of inorganic silicone (trade name AY49- of Toray Silicone Co., Ltd.) was manufactured. 208) was applied, continuous winding was performed with 1/2 overlap winding. Furthermore, instead of the insulating tape 7 made of alumina fiber cloth without adhesive in Example 1, the alumina fiber cloth was filled with inorganic silicone (trade name AY49-208 of Toray Silicone Co., Ltd.). Agent-containing borosiloxane paint (product name SMR- of Showa Denshin Co., Ltd.)
109) and inorganic silicone (trade name AY49-208 of Toray Silicone Co., Ltd.).
While coating the mica tape, an insulating layer was formed by wrapping the mica tape once in a 1/2 overlap. The insulation thickness was the same as in Example 1.

[0021] A polytetrafluoroethylene tape (not shown) for mold release is wrapped around the outside of the insulating layer thus formed, a steel plate is applied, and then a heat-shrinkable polyester tape is wrapped around this. 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, iron plate, and 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. A heat-resistant insulated wire was obtained.

In the above manufacturing process, the pressurization 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 a high temperature. The material was mineralized (ceramized) and a completely inorganic insulating layer was formed. Example 2

A U-shaped insulating molded product 7 as shown in FIG. 2 was used on top of the conductor of Example 1, and insulated by wrapping it with the mica sheet cut into strips of Example 1. That is, the ends of the molded insulating plates were overlapped, and the conductors were insulated so that they overlapped by 1/2 in the longitudinal direction. moreover,
As in Example 1, wrap an insulating tape made of alumina fiber cloth without adhesive on top of the inorganic silicone (Toray Silicone Co., Ltd.'s product name: AY49-) to prevent the end from loosening. 208) was applied and stopped. The insulation thickness was the same as in Example 1. Thereafter, an insulated coil was manufactured in the same manner as in Example 1. Here, a method for manufacturing a molded insulating plate will be described. The mica sheet used in Example 1 was placed in a U-shaped mold, heated at 80°C for 1 hour, and heated at 130°C for 2 hours.
It was cured by heating at 150° C. for 2 hours. Since the molded insulating plates produced in this way are flexible, they easily conform to the conductor, and the molded insulating plates can be easily stacked on top of each other. In addition, insulating molded products can be coated with inorganic insulation tape that does not have adhesives.
By alternately pressing and winding the material with a roll, high voltage insulation with a thick insulation layer can be produced.

Furthermore, if a ceramic molded product is used as the insulating molded product, a high voltage insulated wire ring with greater mechanical strength can be manufactured. Examples of ceramic molded bodies include alumina (A
l2O3 ), steatite (MgO・SiO2 ),
Examples include aluminum nitride (AlN), boron nitride (BN), and zircon (ZrO2.SiO2).

When the heat-resistant insulated wires obtained in Examples 1 and 2 and the comparative example were heat cycled 1000 times between 50°C and 650°C, the comparative example was the fastest, and the alumina woven wire on the insulating surface Cracks occurred in the cloth tape and the alumina fibers were cut. As the number of heat cycles increased, this crack spread to the surface of the insulating layer, and the crack itself also expanded. In contrast, in Examples 1 and 2, no cracks were observed even after 1000 heat cycles. The residual breakdown voltage after 1000 heat cycles (the percentage of breakdown voltage after heat cycle deterioration with respect to the initial value of breakdown voltage) was 92% in Example 1 and 90% in Example 2. , the residual dielectric breakdown voltage of the insulated coil of the present invention was high at 55% in the comparative example. Also,
As a result of a disassembly investigation of the insulating layer, the mica tape in the comparative example was found to have broken in some places. This is because thermal stress is applied in the longitudinal direction of the mica tape due to the difference in thermal expansion between the conductor and the insulating layer, so the mica tape cannot withstand it and breaks. On the other hand, in Examples 1 and 2, the mica sheet is wrapped in the longitudinal direction in advance, so that even if thermal stress is applied, the wrapping stitches are cleverly shifted and the mica sheet does not break.

[0026]

[Effects of the Invention] As explained above, according to the present invention, strip-shaped mica sheets made by bonding an inorganic reinforcing material with an adhesive made of inorganic silicone or an inorganic paint are stacked together. Since the conductor is wrapped and a non-adhesive inorganic insulating tape is wound over the conductor, a heat-resistant insulated wire ring with excellent electrical and mechanical properties can be obtained. Furthermore, even if the heat-resistant insulated coil is repeatedly subjected to heat cycles that occur when the equipment is started and stopped, the insulating layer does not crack, and the insulating layer hardly deteriorates. Therefore, it is possible to provide a method for manufacturing a heat-resistant insulated coil used at high temperatures of 300° C. or higher, such as an electromagnetic pump for circulating liquid sodium in a fast breeder reactor.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a heat-resistant insulated coil showing an embodiment of the present invention.

FIG. 2 is a perspective view of an insulating molded product used in another embodiment of the present invention.

[Explanation of symbols]

1... Conductor 2... Nickel-plated alumina dispersion reinforced copper 3... Mica tape 4... Inorganic adhesive 5a, 5b... Strip-shaped mica sheet 6... Inorganic insulation tape without adhesive 7... Insulating molded product

Claims (1)

[Claims] [Claim 1] A conductor is wrapped by overlapping strip-shaped mica sheets made by laminating an inorganic reinforcing material with an inorganic adhesive,
After wrapping an inorganic insulating tape with high mechanical strength, excellent heat resistance, and no adhesive on top of this,
A method for manufacturing a heat-resistant insulated wire, characterized by firing at a temperature of ℃ or higher.