JP2000125498A - Insulation structure of three-phase ac dynamoelectric machine stator coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the insulation structure of a three-phase AC dynamoelectric machine stator coil, by which creeping discharge along the end part of a slot corona preventive layer can be avoided effectively. SOLUTION: A three-phase AC dynamoelectric machine stator has main insulating layers 3, which are formed by applying insulating material such as mica tape, etc., to the surfaces of stator coils 2 attached to a stator core 1, slot corona preventing layers 4 which cover the surfaces of the main insulating layers 3, and further are formed on the parts of the stator coils 2, which are housed in slots 11 and protrude from the end parts of the stator core 1 and duct pieces 5, which are made to protrude from the end surfaces of the stator cores 1. A field relief layer 6 is formed over the whole circumference of each slot corona preventing layer 4 at a position protruding slightly from the tip of the duct piece 5 with a winding tape, nonwoven fabric or woven fabric a plurality of turns to make the slot corona preventing layer 4 have a thickness, with which the maximum field intensity at the tip of the slot corona preventing layer 4 is made to be not higher than 2.0 kV/mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an insulation structure for a stator coil for a three-phase AC rotating machine.

[0002]

2. Description of the Related Art Conventionally, an insulating structure of a stator and a stator coil for a three-phase AC rotating machine is as shown in FIGS. 4A and 4B (first conventional example). 1 is a stator core formed by laminating thin steel plates, 11 is a plurality of slots provided to extend in the axial direction of the stator core 1, 2 is a slot passing through the slot 11, and both ends of the stator core 1 The stator coil mounted so as to protrude from the part, 2a is an electric wire of each phase of the stator coil, and 3 is formed by winding an insulating material such as a film-backed mica tape on the surface of the electric wire 2a of the stator coil. The main insulating layer 4 has a portion accommodated in the slot 11 of the stator coil 2 and a portion protruding from the end of the stator core 1,
It is a slot corona prevention layer formed so as to cover the surface of the main insulating layer 3. 5 is mainly an electric wire 2 of each phase of the stator coil.
For the purpose of guiding the cooling air flowing between a,
This is a duct piece provided so as to protrude from the end face of the stator core 1. Reference numeral 7 denotes a protective layer made of an insulating material provided on the outer periphery of a position extending over a part of the slot corona preventing layer 4 and a part of the main insulating layer 3. It is wound once. .
Among them, the slot corona prevention layer 4 is generally made of a semiconductive resin having a surface resistivity of about 10 ³ Ω and mixed with a conductive powder such as carbon for the purpose of preventing air discharge at the end of the stator core. It is composed of a tape coated or dried on a cloth or a film, or a sheet formed by winding or flat winding a sheet a plurality of times. FIG. 5 is FIG.
FIG. 4 is a model diagram used for a two-dimensional electric field analysis by a finite element method based on the shape D of the stator coil of FIG. Electric field between adjacent slot corona prevention layer and protection layer when the length of the piece X2 = 10 mm, the thickness of the duct piece 5 X3 = 2 mm, and the spatial distance between the stator coil and the duct piece X4 = 4.5 mm It is a potential distribution obtained from the calculation. Here, in the analysis, the voltage applied to the electric wire is changed to the peak value of the operating voltage of 5400 V [= (660
0 / {3) × {2], the voltage applied to the slot corona prevention layer was 0 V, and the dielectric constant of the main insulating layer was 4.0. From this result, the equipotential lines are dense in the main insulating layer at the end of the slot corona prevention layer, that is, the electric field is concentrated most, and the maximum electric field value is 7.5 kV / mm. In air, the electric field is concentrated most at the end of the slot corona prevention layer, and the maximum electric field value is 2.2 kV / mm. On the other hand, the dielectric breakdown voltage of the main insulating layer 3 is 30 kV / mm or more as x-3σ as a result of the actual measurement, and is four times higher than the above-described calculation result of 7.5 kV / mm. Conceivable. In the case of air, the dielectric breakdown electric field value in an equal electric field of air is calculated from the document shown in FIG. 6 (IEEJ Ozonizer Technical Committee: Ozonizer Handbook, published by Corona Co., Ltd., Showa 35, p. 194).
2. When the clearance length is 11 mm (= 4.5 + 2 + 4.5 mm).
It becomes 17 kV / mm. In addition, as a second conventional example, about 10 ⁸ is overlapped with the end of the slot corona prevention layer.
There is an insulating structure in which a high-resistance end corona preventing layer made of a material having a surface resistivity of Ω is formed, or, as a third conventional example, an insulating structure in which an end of a slot corona preventing layer is bent and contacted by a reaction force. . Further, as a fourth conventional example, there has been proposed a structure in which a heat-shrinkable tube is wound around the outer periphery of an overlapping portion of a slot corona prevention layer and a high-resistance end corona prevention layer.

[0003]

However, the prior art has the following problems. (1) In the first conventional example, since the actual breakdown electric field value in the air causes an air discharge at an electric field value lower than the calculated value obtained from the above document, the electric field calculation result described above is obtained. 2.2 kV / mm is a value with no margin.
Therefore, creeping discharge cannot be prevented at the end of the slot corona prevention layer. (2) In the insulating structure in which the high-resistance end corona preventing layer is overlapped at the end of the slot corona preventing layer shown in the second conventional example, the contact resistance between both the preventing layers increases over a long period of time. (3) In the insulating structure in which the end of the slot corona preventing layer shown in the third conventional example is bent and brought into contact by a reaction force, the slot corona preventing layer and the high-resistance end corona preventing layer are in point contact with each other. In the long term, the resistance value becomes unstable due to the difference in thermal expansion of the constituent materials, and the reliability is lacking. (4) In the insulation structure in which the heat-shrinkable tube is wound around the overlapped portion of the slot corona prevention layer and the high-resistance end corona prevention layer shown in the fourth conventional example, the material cost becomes high, and the manufacturing time is increased. Take it. Accordingly, the present invention provides a stator coil for a three-phase AC rotating machine that can reduce the maximum electric field value in the air at the end of the slot corona prevention layer without using a high-resistance end corona prevention layer and can prevent creeping discharge. It is an object of the present invention to provide an insulating structure.

[0004]

In order to solve the above problems, the present invention provides a stator core formed by laminating thin steel plates, a plurality of slots extending in the axial direction of the stator core, and a plurality of slots. A stator coil mounted so as to pass through and from both ends of the stator core;
A main insulating layer formed by winding an insulating material such as mica tape around the surface of the stator coil; a portion covering the surface of the main insulating layer and housed in a slot of the stator coil; In the stator for a three-phase AC rotating machine, comprising: a slot corona prevention layer formed at a portion protruding from an end of an iron core; and a duct piece provided to protrude from an end surface of the stator core. A plurality of tape-shaped or sheet-shaped insulating materials are provided on the outer periphery of the slot corona prevention layer and the main insulating layer over a range slightly protruding from the front end of the slot corona prevention layer toward the axial direction from the front end of the slot. An electric field relaxation layer formed by winding is provided, and the slot corona prevention layer has a maximum electric field value of 2.0 kV / mm in air of the slot corona prevention layer.
It is characterized by having the following thickness.
By the above means, it is possible to reduce the maximum electric field value in the air at the end of the slot corona prevention layer, air discharge,
That is, creeping discharge can be prevented.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an insulation structure of a stator coil for a three-phase AC rotating machine showing an embodiment of the present invention,
FIG. 2A is a side view of a stator, and FIG. 2B is a cross-sectional view of a main part A in which an insulation structure of a stator coil is enlarged. The configuration in which the present invention is different from the conventional one is as follows. That is, over the range slightly protruding from the tip end of the duct piece 5 toward the axial direction from the tip end of the slot corona prevention layer 4, the organic material having excellent impregnating properties on the outer periphery of the slot corona prevention layer 4 and the main insulating layer 3 is used. The electric field relaxation layer 6 made of a tape, a nonwoven fabric, or a woven fabric made of an inorganic insulating material is wound a plurality of times. The slot corona prevention layer 4 has a maximum electric field value in the air at the tip of the slot corona prevention layer 4,
It has a thickness of 2.0 kV / mm or less. FIG. 2 is a model diagram used for a two-dimensional electric field analysis by the finite element method based on the stator coil shape B of FIG.
The results obtained from the calculation of the electric field between the adjacent slot corona preventing layer and the electric field relaxing layer, with the dielectric constant of the electric field relaxing layer being 4.0, are shown. As a result, it was confirmed that the maximum electric field value in air was reduced to 1.0 kV / mm. Furthermore, in order to verify the effect of the electric field relaxation layer 6, partial discharge characteristics were actually measured in the model coil, and the effect of the electric field relaxation layer 6 was verified. The model coil has the same shape as that used for the electric field calculation. The electric field relaxation layer 6 has a thickness of 0.13 at the end of the slot corona prevention layer 4.
It was formed by winding a glass tape of 20 mm 20 times. FIG. 3 shows the measurement results of the partial discharge characteristics. From now on, the electric field relaxation layer 6
When there is, the partial discharge starting voltage increases, and the maximum discharge charge at each applied voltage also decreases. That is, the partial discharge characteristics are improved, and it is clear that the external insulating layer 6 is effective. Therefore, at the position slightly protruding from the end of the slot corona prevention layer toward the axial direction from the end of the duct piece, the entire circumference of the slot corona prevention layer is made of an organic or inorganic insulating material having excellent impregnation properties. The electric field relaxation layer made of a nonwoven fabric or a woven fabric is wound a plurality of times, and the slot corona prevention layer is formed to a thickness such that the maximum electric field value in the air at the tip of the slot corona prevention layer becomes 2.0 kV / mm or less. With the setting, the electric field concentration is reduced in the air at the end of the slot corona prevention layer, and the creeping discharge can be prevented. As a result, the partial discharge characteristics can be improved, and the life of the rotating machine can be extended.
The thickness of the tip of the slot corona preventing layer varies depending on the dielectric constant of the insulating material used for the slot corona preventing layer. Therefore, it is preferable to appropriately select the insulating material so as to satisfy the set maximum electric field value in air.

[0006]

As described above, according to the present invention, the length from the tip of the duct piece to the position slightly protruding from the tip of the slot corona prevention layer is set so that the entire circumference of the slot corona prevention layer is organic. Alternatively, an electric field relaxation layer made of a tape, a nonwoven fabric, or a woven fabric made of an inorganic insulating material is wound a plurality of times, and the maximum electric field value in the air at the tip of the slot corona prevention layer is 2.0 kV / With the insulating structure set to have a thickness of not more than mm, the electric field concentration is reduced in the air at the end of the slot corona prevention layer, and creeping discharge can be prevented. That is, there is an effect that the partial discharge characteristics can be improved and the life of the rotating machine can be extended.

[Brief description of the drawings]

FIG. 1 is a diagram showing an insulation structure of a stator coil for a three-phase AC rotating machine according to an embodiment of the present invention, wherein (a) is a side view of the stator and (b) is an insulation structure of the stator coil. It is sectional drawing of the principal part A which expanded.

FIG. 2 is a model diagram used for a two-dimensional electric field analysis based on a finite element method based on a stator coil shape B of FIG. 1, which is obtained from an electric field calculation between an adjacent slot corona prevention layer and an electric field relaxation layer. FIG.

FIG. 3 is an actual measurement result of a partial discharge characteristic of the present invention.

4A and 4B are diagrams showing an insulation structure of a conventional stator coil for a three-phase AC rotating machine, wherein FIG. 4A is a side view of the stator, and FIG.
FIG. 3 is a cross-sectional view of a main part C in which an insulation structure of a stator coil is enlarged.

FIG. 5 is a model diagram used for a two-dimensional electric field analysis by a finite element method based on the shape D of the stator coil of FIG. 4, which is obtained from an electric field calculation between an adjacent slot corona prevention layer and a protective layer. It is a figure showing a potential distribution.

FIG. 6 is a diagram showing a relationship between a gap length and a dielectric breakdown electric field value in an equal electric field of air.

[Description of Signs] 1: Stator core 11: Slot 2: Stator coil 2a: Electric wire 3: Main insulating layer 4: Slot corona prevention layer 5: Duct piece 6: Electric field relaxation layer 7: Protective layer X1: Stator core Length of slot corona prevention layer from end X2: Length of duct piece from stator core end X3: Thickness of duct piece X4: Spatial distance between stator coil and duct piece

Claims (1)

[Claims] 1. A stator core formed by laminating thin steel plates, a plurality of slots extending in the axial direction of the stator core, and projecting from both ends of the stator core through the slots. A stator coil mounted to
A main insulating layer formed by winding an insulating material such as mica tape around the surface of the stator coil; a portion covering the surface of the main insulating layer and housed in a slot of the stator coil; A stator for a three-phase AC rotating machine, comprising: a slot corona prevention layer formed at a portion protruding from an end of an iron core; and a duct piece provided to protrude from an end face of the stator core. A plurality of tape-shaped or sheet-shaped insulating materials are provided on the outer periphery of the slot corona prevention layer and the main insulating layer over a range slightly protruding from the front end of the slot corona prevention layer toward the axial direction from the front end of the slot. An electric field relaxation layer formed by winding is provided, and the slot corona prevention layer has a maximum electric field value of 2.0 kV / mm or less in the air of the slot corona prevention layer. An insulation structure for a stator coil for a three-phase AC rotating machine, characterized by having a thickness.