JPH08182269A - Manufacture of high voltage rotary machine - Google Patents

Abstract

PURPOSE: To obtain a high voltage rotary machine being stable for a long period of time by providing good contact at the overlapping portion between a low resistance corona prevention layer and an electric field easing layer by placing conductive tape or sheet on the surface of the low resistance corona prevention layer formed on an insulating layer against ground and winding voltage nonlinear type semiconductive tape. CONSTITUTION: A low resistance corona prevention layer 4 is formed by winding low resistance corona prevention tape 4a around a linear portion of a stator coil 1 forming an insulation layer 3 against ground by winding prepreg mica tape 3a around strand conductor group 2 covered with insulation; further, this stator coil 1 is heat-pressed and heated, pressured and formed to predetermined dimensions. Next, unwoven tape of a conductive material 6 is wound on the surface of the low resistance corona prevention layer 4 of the portion overlapped by the low resistance corona prevention layer 4 and electric field easing layer 5, and the electric field easing layer 5 is formed by winding a voltage nonlinear type semiconductive tape 5a over the unwoven tape, thereby forming the high voltage stator coil 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage rotating coil for preventing the external corona of the coil, and extending the life of the coil in the vicinity of the superconducting low-resistance tape layer and the electric field relaxation layer, especially in a high electric field. The present invention relates to a method for manufacturing a rotating machine coil.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. A stator coil (hereinafter referred to as a high voltage stator coil) 1 of a high voltage rotating machine is housed in a stator iron core slot 7a, and during operation, it is grounded to a group of bare wire conductors 2 of the stator coil and grounded. Since there is a rated voltage / 3 ^1/2 , that is, a potential difference of several kV or more between the formed stator cores 7,
If there is a gap between them, a partial discharge (also called corona discharge) occurs in the gap and damages the ground insulating layer 3. Further, near the outlets on both sides of the slot 7a, the electric field is more concentrated than in the slot 7a, and partial discharge or creeping discharge is likely to occur. Therefore, an insulating tape mainly composed of mica paper having excellent corona resistance is used for the ground insulating layer 3. The above insulation methods are roughly classified into two types. 1
One of the methods is to use a mica tape (referred to as dry mica tape) 33a in which a backing material of an insulating tape and a mica paper are bonded together with a minimum amount of adhesive, and the coil 1 is wound a predetermined number of times on the stator core 7. Store. After that, it is a so-called VPI (Vacuum Pressure Impregnation) type insulation method in which wiring is performed, thermosetting resin such as epoxy or polyester is impregnated in a vacuum and pressure, and heat curing is performed, which is a so-called VPI (Vacuum Pressure Impregnation) type insulation method. Pre-impregnated Tape 3a, which is semi-cured by fully impregnating the above mica tape with resin, is wound a predetermined number of times and then coiled by heating with a heat press. It is a method of storing it in the iron core 7 and connecting and finishing it (hereinafter referred to as Resin Rich method). Since the present invention can be improved by implementing either method, the latter, that is, the resin rich method will be described below.

In order to prevent the above partial discharge and creeping discharge, a prepreg tape 3a is wound as a ground insulating layer 3 a predetermined number of times, and several tens of mm are wound on each side of the slot length SL of the straight part of the coil 1 on the prepreg tape 3a. A semi-conductive low resistance (hereinafter referred to as low resistance corona prevention) tape or sheet 4a is wound in a lengthened range to form the low resistance corona prevention layer 4. In order to finish this coil 1 to a specified size,
Apply to heat press machine and heat / mold. The surface resistivity of the low resistance corona preventive layer 4 is on the order of 10 ³ to 10 ⁴ Ω. By setting this value to such a value, when it is housed in the slot 7a of the iron core after heating and molding, By making contact, the potential of the surface of the coil 1 approaches the ground potential, and the occurrence of partial discharge can be prevented.

Although the inside of the slot is good only with the low resistance corona preventive layer 4 described above, the electric field is concentrated at both ends of the low resistance corona preventive layer 4, so that partial discharge occurs and damages the ground insulation. Further, when a rotary electric machine is newly manufactured, the high voltage stator coil 1 is housed in the slot 7a and connected to form a stator winding. In the process of making it, a withstand voltage test is conducted several times in conformity with JEC-114 (1979) of the Electrical Standards Committee to check the quality, but when E> 6 kV, 2E + 3 (kV).
A high voltage (E: rated voltage) is applied, creeping discharge occurs outside the slot, and the withstand voltage characteristic deteriorates.

In order to prevent this, a voltage non-linear semi-conductive tape 5a is wound around the low-resistance corona preventing layer 4 for a predetermined length so as to overlap with the low-resistance corona preventing layer 4 to form an electric field relaxation layer 5. By utilizing the voltage drooping characteristic of the resistance of the electric field relaxation layer 5, the electric field concentration at both ends of the resistance layer low resistance corona prevention layer 4 is relaxed.

[0006]

By the way, since the interface between the low resistance corona preventive layer and the electric field relaxation layer is wound so tightly, there is no problem in a normal operating state, but it is a problem in the withstand voltage test during new manufacturing. In case of E> 6 kV, 2E + 3 (kV)
A voltage of (E: rated voltage) is applied. Also, in the process of manufacturing the stator winding, the above voltage is applied several times to confirm the quality and proceed. Furthermore, even when the life of the stator coil is experimentally obtained by an acceleration test,
The voltage of 3E may be applied for a relatively long time. At that time, the current flowing into and out of the electric field relaxation layer varies considerably depending on the size of the coil, the thickness of the insulating layer, the rated voltage, etc., but is considerably large, and if the contact resistance between the low resistance corona prevention layer and the electric field relaxation layer is large, A potential difference is generated between the two layers, the temperature rises due to Joule heat, and both layers deteriorate due to discharge generation. As a result, the contact resistance at the interface between the two layers is further increased, and the performance of the electric field relaxation layer is deteriorated.

For this reason, it has been attempted to coat the overlapping portions of both layers with a low-resistance corona-preventing paint or sandwich a metal foil to lower the contact resistance between the two layers. Because of the relationship used in the department,
Many are dried at room temperature, and the heat resistance of the varnish connecting the carbon particles is not good. In addition, the metal foil is vulnerable to an acidic atmosphere, and if the humidity is high in an atmosphere where atmospheric pollution such as nitrogen oxide and sulfur dioxide or partial discharge occurs, the metal foil is oxidized,
Rust and corrosion are generated, which is not preferable.

In order to solve the above drawbacks, the present invention provides
It is an object of the present invention to provide a high-voltage rotating machine coil that improves contact between overlapping portions of the low-resistance corona prevention layer and the electric field relaxation layer and is stable for a long period of time.

[0009]

For this reason, a tape or sheet of a conductive material, or one of roping and strands is wound or sandwiched in the overlapping portion of the low resistance corona preventive layer and the electric field relaxation layer. To do so. The tape or sheet used at this time has a volume resistivity lower than that of the low resistance corona preventive layer.

[0010]

According to the above-mentioned means, when the low resistance corona preventive layer is formed on the ground insulation and then the voltage non-linear semiconductive tape is wound over the predetermined width, the low resistance corona preventive layer is formed. By putting a tape or sheet of conductive material on top and winding a voltage non-linear semi-conductive tape, the contact resistance between them will be lower than without it, and the same characteristics can be maintained over the long term. . It is ideal if the low resistance corona prevention layer and the electric field relaxation layer can be joined by butting, but in reality there are places where they cannot be connected.Therefore, in order to avoid this danger, the low resistance corona prevention layer's low resistance and electric field relaxation layer are avoided. The high resistance of the layers will be superposed, but in this case, a parallel part of low resistance and high resistance will be created on the equivalent circuit, and the potential of this part will be high, but the incomplete contact of the potential Since the disturbance is larger, there is no practical problem.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a high voltage stator coil will be described below with reference to FIGS. The same parts as those of the related art are designated by the same reference numerals. FIG.
1 is a perspective view for explaining a method of manufacturing a high voltage stator coil showing an embodiment of the present invention, and FIG. 2 is a main part of FIG.
The expanded perspective view which carried out the half cross section by the surface is shown.

The high voltage stator coil 1 before being housed in the slot 7a of the stator core 5 is first shaped into a rectangular cross section, and the prepreg tape 3a is attached to the insulating coated wire conductor group 2 according to the rated voltage. , The ground insulation 3 is formed by winding a predetermined number of times in a lap winding, and then the straight portion of the stator coil 1 is provided with a glass cloth base material low resistance corona prevention tape or sheet 4a so that every portion has one or more layers. Then, the low resistance corona preventive layer 4 is formed. Further, this coil 1 is subjected to a heat press machine and subjected to heating and pressure molding to a predetermined size.

With respect to the coil 1 that has been heat-pressed, sandpaper is applied to the surface of the low-resistance corona prevention layer 4 in the portion where the low-resistance corona prevention layer 4 and the electric field relaxation layer 5 overlap each other, and a ground insulating layer is applied during heat pressing. The resin exuding from 3 is removed. Next, in the overlapping portion of the low-resistance corona prevention layer 4 and the electric field relaxation layer 5, one of heat-resistant carbon fiber, silicon carbide fiber, nickel-plated organic fiber, and oxidation-resistant nickel-plated aluminum fiber is used. Woven tape or sheet of conductive material, non-woven tape or sheet,
Any one of a mat-shaped tape or sheet, a felt-shaped tape or sheet, a string-shaped roving or a strand is wound or sandwiched, and a voltage non-linear semi-conductive tape 5a is formed on this layer in two layers with a predetermined length. The winding is performed as described above, the electric field relaxation layer 6 is formed, and the high voltage stator coil 1 is formed.

The high voltage stator coil 1 manufactured as described above has a heat resistance of type F (maximum temperature 155 ° C.) and a rated voltage of 1
Regarding the specifications of 3.8 kV, the dimensional relationship of various tapes such as the low resistance corona prevention tape 4a will be described. The low-resistivity corona-preventing tape 4a is a thin glass cloth as a base material, and a heat-resistant polyester varnish containing conductive carbon black is applied on both sides and heat-cured 0.15 mm.
It is a semi-conductive cloth of thickness, which is a slot SL + 30 mm width on each side and wound in 1/4 sushi rolls. Commercially available products are, for example, Arizawa Seismic cloth ( 0.13-E) and Hitachi Chemical's semi-conductive corona shield tape (CST-12G).

The voltage non-linear semi-conductive tape 5a has a thickness of 0.20 to 0.22 mm, which is obtained by applying epoxy varnish containing silicon carbide fine powder to both sides of thin glass or polyester cloth of its base material and heat curing. It is a tape of Sao. A commercially available product that is obtained by winding this half-wrap once, for example, is Semi Conductive CoronaPr of ISOLA.
otection Tape (No.217.01, No.217.02), ISOVOLTA EG
SB (Enden Glimm Schu-tz Band) (VP310), etc. The overlap of the low resistance corona prevention tape layer 4 and the electric field relaxation layer 5 is 10
~ 20 mm. The conductive material 6 has a fibrous shape rather than a smooth surface such as a metal foil because the low resistance corona prevention tape layer 4 and the electric field relaxation layer 5 both have a woven fabric as a base material and have irregularities at the surface where warp threads and weft threads intersect. The contact state is better and is preferable. Here, we collected 3000 filaments of Toho Bethlon carbon fiber,
One layer of strand (ST-1) was wound. The conductive material 6 includes
In addition, carbon fiber woven fabrics such as Toho Bethlon's plain weave cloth (W-1103) and silicon carbide fibers such as Nihon Carbon's Nicalon tape, paper and mat are commercially available. Kevlar fiber-plated products and aluminum fiber-plated products have been put into practical use depending on the application and can be applied to the present invention.

During operation, the high-voltage stator coil 1 produced as described above has a maximum temperature of 155 ° C. and a voltage of E / 3 ^1/2 (E: rated voltage) as a ground voltage is applied. However, this was continuously carried out at 2E (27.6 kV) voltage acceleration test at 155 ° C., and the deteriorated states of the low resistance corona preventive layer 4 and the electric field relaxation layer 6 were observed. At the same time, as comparative examples, one in which the low resistance corona preventive tape layer 4 and the electric field relaxation layer 5 were simply stacked and one in which a low resistance corona preventive paint was applied instead of the carbon fiber were prepared and compared and tested. Was carried out. The results are as shown in Table 1 for the long-term test, and this example was the most excellent result.

[Table 1] For the short-time test, a simple heavy winding (comparative example) and a carbon fiber strand winding (example) were prepared for the high-voltage stator coil 1 having the rated voltage of 13.8 kV, and 30.6 kV (example) 2E + 3) was applied for 1 minute. As a result, in the former case, a strima and a strong discharge noise due to the creeping discharge were recognized, but in the latter case, the contact of the overlapping part was successful and only a weak discharge noise was generated.

[0017]

As described above, the examples of the present invention were superior to the conventional methods in both long-term and short-term tests.
Therefore, it can be seen that the effect of the present invention is great, not only in the overvoltage of the short-time withstand voltage test, but also in the long-life test, which can expect good characteristics for a long period of time, facilitates the maintenance.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining a method of manufacturing a high voltage stator coil according to an embodiment.

FIG. 2 is an enlarged perspective view in which a main part of FIG. 1 is half-sectioned along a plane A-AA.

FIG. 3 is a perspective view for explaining a method of manufacturing a conventional high voltage stator coil.

FIG. 4 is an enlarged perspective view in which a main part of FIG. 3 is half-sectioned along a plane A-AA.

FIG. 5 is a perspective view of an element conductor group in which the stator coil is shaped.

[Explanation of symbols]

 1 high voltage stator coil 2 group of strand conductors with shaped stator coil 3 ground insulation layer 3a prepreg mica tape 33a dry mica tape 4 low resistance corona prevention layer 4a low resistance corona prevention tape 5 electric field relaxation layer 5a voltage nonlinear Semi-conductive tape 6 Conductive material 7 Stator core 7a Slot SL Slot length

Claims (3)

[Claims] 1. A insulated coil is formed by winding a predetermined number of turns, a stator coil is formed, an insulating layer is provided on the outer periphery of the stator coil, and a semiconductive low resistance tape or sheet is further wound on the insulating layer to heat it. In a coil of a high voltage rotating machine formed by pressure molding, both ends of the low resistance tape layer of the coil after heating and pressure molding, and an electric field relaxation layer having a voltage non-linear resistance characteristic wound in a predetermined width. A method for manufacturing a high-voltage rotating machine coil, which is characterized in that a conductive material is sandwiched in an overlapping portion with and. 2. The conductive material is formed of any one of heat resistant carbon fiber, silicon carbide fiber, nickel plated organic fiber, and oxidation resistant nickel plated aluminum fiber. The method for manufacturing a high-voltage rotating machine coil according to claim 1, which is characterized. 3. The conductive material is one of a woven tape or sheet, a non-woven tape or sheet, a mat-shaped tape or sheet, a felt-shaped tape or sheet, a string-shaped roving or a strand. 2. The method for manufacturing a high voltage rotating machine coil according to claim 1, wherein