JPS5826643B2 - Coil insulation structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an insulating structure of a coil used in a rotating electric machine such as a generator or an electric motor.

In general, it has been known for a long time that electrodeposited insulation, which mainly consists of natural mica powder, can be applied to coil insulation of medium- and large-sized rotating machines or fire-resistant electric wires, but it has not yet been put to practical use.

The reason for this is that when electrodepositing only natural mica powder, the strength of the electrodeposited layer is poor, and when the object to be coated is removed from the electrodeposition bath, the mica powder deposited on the object falls off, making it practically unusable. The migration speed of natural mica powder is very slow (the desired film thickness cannot be obtained unless it is electrodeposited at high voltage for a long period of time, and when high voltage is applied, the metal to be coated is Elution, the liquid properties of the electrodeposition bath change over time, and the specific gravity of natural mica powder is too high, which increases the sedimentation rate. To prevent this, high-speed stirring is required, and for this reason, the electrodeposition layer The disadvantages include that the surface becomes irregular due to unevenness.

Therefore, as one method to solve these problems, the present inventors proposed a method in which water-dispersed varnish was added to a dispersion of natural mica powder and electrodeposited (for example, in
No. 1-89178, JP-A-51-114602 2%:
This water-dispersed varnish (Japanese Patent Publication No. 114603/1983) serves as a binder for the mica powder in the electrodeposited layer, and if the amount added is small, the strength of the electrodeposited layer will not be sufficient, and the coil Care must be taken to ensure that the electrodeposited layer does not fall off when strands are bundled and tied together.

However, when a resin is impregnated in a subsequent step, since the porosity of the electrodeposited layer is large, the impregnation is easy, which is advantageous in terms of insulation properties and work efficiency.

Furthermore, when the amount of water-dispersed varnish added is large, the strength of the electrodeposited layer is improved, but the porosity of the mica layer is reduced, resulting in poor impregnability.

Therefore, the amount of water-dispersed varnish added affects the strength and impregnability of the electrodeposited layer, and since these properties tend to contradict each other depending on the amount added, the viscosity of the impregnated varnish, the applied pressure, the time, etc. It is a characteristic that a compromise must be found by considering impregnation conditions, insulation properties, work efficiency, etc.

Another reason for the poor impregnability of the electrodeposited layer is that the mica pieces in the electrodeposited layer are deposited parallel to the conductor, and the creepage distance from the surface of the electrodeposited layer to the conductor is much longer than that of thin sheet materials. This is due to the long period of time.

However, it is well known that using an electrodeposited layer of mica powder as an insulating layer of a heat-resistant insulated conductor has many advantages in terms of heat resistance.

In other words, in the case of an insulated conductor with a structure in which a scaly inorganic insulating material such as mica is layered on a conductor and the gaps between the layers are filled with insulating varnish, the coil may be abnormally heated for some reason, causing the organic material to become insulated. This is because even if the insulating varnish deteriorates due to heat and ceases to function as an insulator, it can fully guarantee the advantage that it will function perfectly in the gaps between the mica layers and its corona resistance.

As described above, although the mica electrodeposition layer has disadvantages in mechanical strength and impregnability, it has the advantage that the film thickness can be freely controlled and has excellent heat resistance.

On the other hand, to insulate the wires of conventional medium- and large-sized high-voltage rotating machines, taping is done with a thin insulation material made of a composite of organic and inorganic materials in consideration of corona resistance, or in low-voltage machines, taping is done with thin insulation materials made of organic or inorganic fibers such as glass. It has been used to wrap the wire around a wire conductor and coat it with insulating varnish.

In any case, these insulation methods using taping are mechanically very strong, but on the other hand, because the taping is done manually, the thickness tends to vary (and requires a lot of labor).

If these conventional wire insulation methods are performed using the electrodeposition method described in 7 above, the taping work that was previously required is no longer necessary, and there is little variation in thickness (also, the heat resistance is low due to the mica electrodeposition layer). It has industrial advantages such as improved film thickness and ability to freely control film thickness.

However, damage to the electrodeposited layer caused by handling such as when inserting an electrodeposited coil into a core, and an increase in impregnation time and impregnation pressure due to the slow penetration rate of the impregnating varnish into the electrodeposited layer. At present, it has not been possible to obtain a practical product because it includes drawbacks such as pressure and the use of low viscosity varnish.

This invention has been made in view of the above points, and eliminates the above-mentioned drawbacks by combining a wire insulating layer formed by a conventional method and a wire insulating layer formed by a mica powder electrodeposition method so that they are adjacent to each other and in contact with each other. However, it provides a coil insulation structure that takes advantage of each other's strengths.

That is, according to the present invention, in order to strengthen the strength of the wire insulating layer formed by the mica powder electrodeposition method and to improve workability, the amount of water-dispersed varnish added is increased, thereby reducing the risk of poor impregnability of the insulating varnish. Even if the amount of water-dispersed varnish added is reduced to improve impregnability, and as a result there is a risk that the electrodeposited layer will be damaged during taping, etc., the strands can be taped with good impregnability. Since the insulating layers are arranged adjacent to each other, the electrical characteristics between the strands are sufficiently reliable compared to a strand insulation structure using only the mica electrodeposited layer and the taping insulating layer alone.

In addition, in terms of heat resistance, it is possible to obtain a satisfactory product even if the wire insulating layer made by the conventional method was not sufficient because the wire insulating layers made by the mica powder electrodeposition method, which has high heat resistance, are placed next to each other. .

Moreover, the cost is reduced by halving the need for wire insulation, which requires labor and uses relatively expensive materials, and is of great industrial value.

The formation of the strand insulating layer by the mica powder electrodeposition method uses the above-mentioned known techniques (with no special restrictions).

In this case, it is desirable that the ratio of mica and water-dispersed varnish used is at least one factor of the weight of the mica powder (solid content is heavy).

If the water-dispersed varnish has a coefficient of less than 1, the electrodeposited layer will have good heat resistance, but it is not preferable because it tends to become loose.

(The composition of the electrodeposited layer is almost the same as the composition of the electrodeposition solution.

) Also, conventional techniques and known materials can be used as they are without any special restrictions regarding the method of forming the wire insulation layer by taping, the method of forming the ground insulation layer, and the type of impregnating varnish. They may be selected and used as appropriate.

Furthermore, substantially the same effect can be expected between the mica electrodeposition method and the taping method, even if they are not alternately arranged layer by layer.

An example of a configuration according to the present invention will be described below.

The figure is a sectional view showing a rotating machine coil before impregnation.

In the figure, 1 is a main insulating layer, 2 is a wire conductor, 3 is a wire insulating layer formed by mica electrodeposition, and 4 is a wire insulating layer taped with a thin insulation material.

First, a water-dispersed varnish is added to an aqueous mica powder dispersion to form an electrodeposition coating that is at least one factor (solid content weight range) of the mica powder weight, and is then electrodeposited on the surface of a wire conductor and a thin insulating material. After the taped strands are arranged alternately and bundled as shown in the figure, a thin insulating material is further wrapped around the material to serve as a ground insulating layer, and the material is impregnated with insulating varnish and hardened to complete the insulation of the coil.

Next, the effects of this invention will be explained by giving reference examples and examples.

Reference example 1 Bisphenol type epoxy resin (Epicote 1001,
Shell Chemical Co., Ltd.) SO part (parts by weight, hereinafter expressed as parts by weight)
, 18 parts of tetrahydrophthalic anhydride, 2 parts of water-dispersed varnish mainly composed of 5 parts of ethylene glycol (solid weight)
8 parts of soft natural mica that had passed through a 35-mesh sieve was mixed with 8 parts of the mixture, ion-exchanged water was added thereto, and the mixture was thoroughly stirred to uniformly disperse the mixture to prepare an electrodeposition coating material with a total non-volatile content of 10%.

This electrodeposition paint is placed in a stainless steel electrodeposition bath, and a hexagonal armature coil of a rotating machine is immersed as an object to be coated, and this is used as an anode.The electrodeposition bath is used as a cathode and a DC voltage of 50V is applied between the two electrodes. was applied for 30 seconds to form a uniform electrodeposited layer with a thickness of 0.11 mm after baking in a dry bath.

Six of these were bundled in two rows, and then a Kapton film (manufactured by DuPont) tape was evenly wrapped around them as ground insulation, followed by a Nomec sheet (manufactured by DuPont) and then glass fiber tape.

Next, bisphenol-based epoxy impregnated resin (trade name 6861-2, manufactured by Ryoden Kakai Co., Ltd.) was impregnated into the wire insulating layer and the ground insulating layer simultaneously in this coil to obtain an armature coil.

The characteristics of this insulated conductor are shown in a table.

Reference Example 2 3 parts (solid weight) of water-dispersed varnish obtained in the same manner as Reference Example 1 was mixed with 7 parts of soft natural mica that had passed through a 35-mesh sieve, and ion-exchanged water was added. The mixture was added and stirred well to uniformly disperse the mixture to prepare an electrodeposition coating material with a total non-volatile content of 10%.

This electrodeposition paint is placed in a stainless steel electrodeposition bath, and a hexagonal armature coil of a rotating machine is immersed as an object to be coated, and this is used as an anode.The electrodeposition bath is used as a cathode and a DC voltage of 30V is applied between the two electrodes. was applied for 57 seconds to form a uniform electrodeposited layer with a thickness of 0.11 mm after dry baking.

Six of these were bundled in two rows, and then Kapton film tape was evenly wrapped around them as ground insulation, followed by a Nomex sheet and then glass fiber tape.

Next, following Reference Example 1, this coil was impregnated with a bisphenol-based epoxy resin and cured to obtain an armature coil.

The characteristics of this insulated conductor are shown in a table.

Reference Example 3 Wrap Nomex tape around the hexagonal armature coil of a rotating machine to an average thickness of 0.1 mm, bundle 6 pieces in 2 rows, and then use Kapton film tape as ground insulation in the same way as Reference Example 1. After uniformly layering them, a Nomex sheet was wrapped around them, and then a glass fiber tape was wrapped around them.

Next, this coil was impregnated with a bisphenol-based epoxy resin and cured in accordance with Reference Example 1 to obtain an armature coil.

The properties of this insulated conductor are shown in the table.

Example 1 The hexagonal armature coil and wire insulated conductor obtained in the same manner as in Reference Example 1 and the hexagonal armature coil and wire insulated conductor obtained in the same manner as in Reference Example 3 were alternately used, that is, in the same manner. - Bundle 6 wires in two rows so that the insulating layers are not adjacent to each other. Similar to reference example ■, wrap Kapton film tape evenly, then wrap with Nomex sheet, and then wrap with glass fiber tape. Ta.

Next, the wire insulating layer and the main insulating layer of this coil were simultaneously impregnated with the above-mentioned bisphenol-based epoxy impregnated resin to obtain an armature coil.

The characteristics of this insulated conductor are shown in a table.

Example 2 Water-dispersed varnish containing 9 parts of styrene, 9 parts of ethyl acrylate, and 1 part of glycidyl methacrylate as main components 1.5 parts
(solid content weight) at a ratio of 8.5 parts of soft natural mica that passed through a 35 mesh sieve, and added ion-exchanged water and stirred well to uniformly disperse the total non-volatile content of 15.
Adjusted the electrodeposition paint.

This electrodeposition paint is placed in a stainless steel electrodeposition bath, and a hexagonal armature coil of a rotating machine is immersed as an object to be coated, and this is used as an anode.The electrodeposition bath is used as a cathode and a DC voltage of 50V is applied between the two electrodes. was applied for 25 seconds to form a uniform electrodeposited layer with a thickness of 0.11 mm after dry baking.

This and the hexagonal coil wire insulated conductor of the Nomex winding rotary machine obtained by the same method as in Reference Example 3 were alternately arranged, that is, in two rows so that the wire insulating layers obtained by the same method were not adjacent to each other. 6 pieces were bundled together, and in the same manner as in Reference Example 1, 1 lum of Kabuton soy tape was evenly layered and then wrapped with glass fiber tape.

Next, following Example 1, this coil was impregnated with a bisphenol-based epoxy resin to obtain an armature coil.

The properties of this insulated conductor are shown in the table.

As shown in Reference Examples 1 and 2 in the table, the dielectric strength of a coil having a wire insulating layer with an electrodeposited layer will decrease as the viscosity of the impregnating varnish increases, as it becomes difficult for the varnish to impregnate the wire insulating layer. It is clear that the wire insulating layer obtained by applying the organic thin leaf material as in Reference Example 3 has a very low dielectric strength after thermal deterioration (and is unstable in terms of heat resistance).

In addition, all of the examples were mechanically strong and highly reliable rotating machines could be obtained.

Furthermore, it has been found that similar effects can be obtained using other similar materials.

Conventionally, there is a conductor with a mica layer, which consists of a mica layer, a resin, and a backing agent (for example, Japanese Patent Laid-Open No. 4913259), but since the mica content is small compared to the thickness of the insulating coating, it is However, the thermal properties are easily influenced by the resin and backing agent contained therein, and the compatibility between the impregnated resin and the resin in the mica tape becomes a problem.

On the other hand, the conductor formed by the electrodeposited layer of the present invention has mica uniformly formed and has a large mica content, so it has excellent electrical and thermal properties, and it also has excellent electrical and thermal properties. There is no need to consider compatibility with

Furthermore, by alternately disposing wire insulating layers formed of taped thin sheet materials, the insulation properties can be improved.
Because it depends on the characteristics of the wire insulation layer consisting of the electrodeposited layer,
It has better electrical and thermal properties than conventional insulating layers.

As explained above, according to the present invention, it is possible to obtain a good insulated coil that is highly safe both thermally and mechanically.

[Brief explanation of drawings]

The figure is a sectional view showing the insulation structure of a coil according to an embodiment of the present invention. In the figure, 1 is a ground insulating layer, 2 is a wire conductor, 3 is a wire insulating layer made of an electrodeposited layer of mica, and 4 is a wire insulating layer made of a taped thin sheet material.

Claims (1)

[Scope of Claims] 1. In the insulation structure of a coil comprising a wire insulating layer and a ground insulating layer, which are integrated with an impregnated resin, one of the adjacent wire insulating layers is formed by an electrodeposited layer containing natural mica. A coil conductor having a wire insulating layer formed with a gap that can be filled with the impregnated resin and a coil conductor having a wire insulating layer formed of a taped thin sheet material are alternately arranged without being adjacent to each other. An insulating structure of a coil characterized by being arranged in. 2. The insulating structure of a coil according to claim 1, wherein the electrodeposited layer comprises natural mica and a water-dispersed varnish whose weight is at least one part of the weight of the natural mica.