Title of the invention
Insulating material and windings thereby
Background of the invention
The present invention relates to windings for electric rotary
machines, furthermore, to insulating material for forming an
insulating film for windings of electrical machines.
Conventionally, insulating film for electrical windings used in
electric rotary machines have been formed with an insulating material
such as, for instance, disclosed in JP-A-63-110929 (1988). That is,
the insulating material comprising a mica layer, a reinforcement layer,
a filler layer including fillers having a high thermal conductivity
therein, and resin contained in each layers has been used. The
insulating material was wound around the outer periphery of the
wound conductors, and the insulating film for windings of electrical
machines was formed by curing the resin in the insulating material
under a pressurizing state.
Summary of the invention
The insulating film for windings of electrical machines formed
as described above with the insulating material as described above did
not have any problem as far as it is used for the electric rotary
machines operated with a low voltage. However, when it was used
for electric rotary machines operated with a high voltage such as
commercial power generators, high voltage motors, and the like,
electrical defects have boon readily generated, and its electrical
characteristics had a tendency to be deteriorated.
In view of the above problems, the inventors of the present
invention have studied reasons to make the electrical defects be
readily generated. As the result, it was found that the reasons were
as follows;
The reason was found that, when forming the insulating film
for windings of electrical machines, a part of fine bubbles contained in
any of the mica layers, filler layers, and the resin were not removed
with a part of the resin containing them, and were remained in the
insulating material. And, this was caused by insufficient flow of
impregnated resin in the insulating film during the pressurizing
process when forming the insulating film for windings of electrical
machines, because the resin content in each of the mica layer and the
filler layer was not maintained at an appropriate content.
The present invention is aimed at providing windings for
electrical machines having insulating film superior in electric
characteristics. Furthermore, the present invention is aimed at
providing insulating material, which makes it possible to obtain the
insulating film for windings of electrical machines superior in electric
characteristics.
The insulating material relating to the present invention
comprises a mica layer, a reinforcement layer, and a filler layer, and
concurrently, a resin content in each of the mica layer and the filler
layer is specified to the range of 10-25 % by weight of total weight of
the insulating material.
The mica layer comprises mica flakes and/or mica particles.
The reinforcement layer comprises a reinforcing material, for instance,
glass cloth. The filler layer comprises a filler having a thermal
conductivity of at least 5 W/m • K, for instance, alumina. The
insulating material is a laminated body of these layers in the order of
the mica layer, the reinforcement layer, and the filler layer, or of the
filler layer, the mica layer, and the reinforcement layer.
The insulating material further comprises resin, for instance,
epoxy resin. Total content of the resin contained in the insulating
material is in the range of 20-50 % by weight of the total weight of the
insulating material, and the resin content in each of the mica layer
and the filler layer is in the range of 10-25 % by weight of the total
weight of the insulating material.
The reason to specify the resin content in each of the mica
layer and the filler layer at least 10 % by weight of the total weight of
the insulating material is that, when forming the insulating film for
windings of electrical machines, it is necessary to make each of the
mica layer and the filler layer contain resin of at least 10 % by weight
of the total weight of the resin, in order to remove the fine bubbles
contained in each of the mica layer and the filler layer in the
pressurizing process.
The reason to make the resin content in each of the mica layer
and the filler layer equal to or less than 25 % by weight of the total
weight of the insulating material is that, if the resin content in each of
the mica layer and the filler layer exceeds 25 % by weight, of the total
weight of the insulating material, an operability in winding the
insulating material onto the conductor is decreased, and the insulating
material is wrinkled.
The insulating material relating to the present invention is
specified that difference of the resin content in the mica layer from the
resin content in the filler layer is equal to or less than 10 % by weight.
The reason to make the difference of the resin content in the
mica layer and the resin content in the filler layer equal to or less than
10 % by weight is that, if the difference of the resin content in the mica
layer and the resin content in the filler layer exceeds 10 % by weight, a
part of the resin containing the fine bubbles to be removed is
transferred from the layer having a large resin content to the layer
having a small resin content, and is remained therein in the
pressurizing process at forming the insulating film for windings of
electrical machines.
In accordance with the windings for electrical machines
relating to the present invention, the insulating film is formed with
an insulating material comprising a high dielectric strength layer, a
reinforcement layer, and a thermoconductive layer, and the resin
content in respective of the high dielectric strength layer and the
thermoconductive layer is in the range of 10-25 % by weight,
respectively, of total weight of the insulating material.
The high dielectric strength layer is a mica layer comprising
mica flakes. The reinforcement layer is a layer comprising a
reinforcement material, for instance, glass cloth. The
thermoconductive layer is a filler layer comprising a filler having a
thermal conductivity ofatleast 5 W/m*K, for instance, alumina.
Each of the layers comprises a resin, for instance, epoxy resin.
Total resin content is in the range of 20-50 % by weight of the total
weight of the insulating material, and the resin content of the each
layer of the mica layer and the filler layer is in the range of 10-25 % by
weight of the total weight of the insulating material. The difference
of the resin content in the mica layer from the resin content in the
filler layer is equal to or less than 10 % by weight.
The reason to adjust the resin content in each of the mica layer
and the filler layer to the range 10-25 % by weight of the total weight
of the insulating material is to obtain a desired electric characteristics,
for instance, alternating insulation breakdown voltage of 26.5-29.0
kV/mm.
The insulating film for windings of electrical machines is
formed using the insulating material as follows;
First, insulated conductors are wound several times for
forming a wound conductor. Then, the insulating material is wound
around the outer periphery of the wound conductor so that either of
the mica layer, or the filler layer is to be closest to the wound
conductor. Subsequently, a releasing agent is applied onto the outer
periphery of the insulating material. A shape forming jig is attached
to the winding, and an external force is applied from the surface via
the jig. Then, the insulating film is formed by heating at a
designated temperature for curing the resin in the insulating material
with removing the fine bubbles contained in the insulating material
with a part of the resin in the insulating material.
Brief description of the drawings
FIG. 1 is a cross sectional view indicating the material
structure of the high thermoconductive insulating tape of the
embodiment of the present invention;
FIG. 2 is a perspective view indicating the structure of the
windings for electrical machines of the embodiment of the present
invention;
FIG. 3 is a perspective view for explaining a manufacturing
process of the windings for electrical machines of the embodiment of
the present invention;
FIG.4 is a cross sectional view of the generator; and
FIG.5 is a perspective view showing the stator slots.
Detailed explanation of the preferred embodiments of the invention
Hereinafter, an embodiment of the present invention is
explained referring to drawings. A structure of material for the high
thermoconductive insulating tape (high thermoconductive pre-
impregnated tape) of the embodiment of the present invention is
explained hereinafter referring to FIG. la. The high
thermoconductive insulating tape 1 comprises a laminated body,
wherein a mica layer 3 (high dielectric strength layer) comprising a
small mica flakes sheet 2, a reinforcement layer 5 comprising glass
cloth 4, and a high thermoconductive filler layer (thermoconductive
layer) comprising alumina particles 6 are laminated in the order of the
above description. The laminated body also may be formed by
laminating in the order of the high thermoconductive filler layer 7, the
mica layer 3, and the reinforcement layer 5 as shown in Fig.lb.
The high thermoconductive insulating tape 1 also contains the
resin 8 in each of the mica layer 3, the reinforcement layer 5, and the
high thermoconductive filler layer 7, and the total content of the resin
8 is 31.4 % by weight of the total weight of the high thermoconductive
insulating tape 1. The resin content in the mica layer 3 is 12.9 % by
weight of the total weight of the high thermoconductive insulating
tape 1, and the resin content in the high thermoconductive filler layer
7 is 15.0 % by weight of the total weight of the high thermoconductive
insulating tape 1.
The high thennoconductive insulating tape J was prepared as
follows: First, a small mica flakes foil 2 (weight; 165 g/m~)
manufactured by a paper making machine with small mica flakes
dispersed in water, and a glass cloth 4 (weight; 35 g/m2) were prepared.
A resin 8 composed by mixing BF3 monoethylamine 3 parts by weight
into novolak type epoxy resin 100 parts by weight was impregnated
into the small mica flakes foil 2 and the glass cloth 4, and a small mica
flakes sheet (a laminated body of the mica layer 3 and the
reinforcement layer 5) was obtained by adhering the small mica flakes
foil 2 and the glass cloth 4.
The resin 8 composed by mixing BF3 monoethylamine 3 parts
by weight into the novolak type epoxy resin 100 parts by weight, and
alumina particles 6 were mixed so that a weight ratio of the alumina
particles 6 to the resin 8 became 2:1. After adding
methylethylketone of 10 % b}r weight, the resin was applied onto the
side plane of the reinforcement layer 5 of the small mica flakes sheet
by a coater so that the applied amount of the resin became 256 g/m2.
Then, the high thermoconductive insulating sheet was obtained by
evaporating and removing the methylethylketone.
The high thermoconductive insulating tape 1 was obtained by
slitting the high thermoconductive insulating sheet to 30 mm wide by
a slitter.
A structure of winding for electrical machines in the
embodiment of the present invention is explained hereinafter referring
to FIG. 2. The winding for electrical machine 9 comprises a wound
conductor 10 formed by winding plural insulating conductors 10a, and
high thermoconductive insulating film 11 formed at the outer
peripheral portion of the wound conductor 10.
The windings for electrical machines 9 was prepared as
follows: First, a plurality of the insulated conductors 10a are wound
several times for forming a wound conductor, as indicated in FIG. 2.
Then, the high thermoconductive insulating tape 1 indicated in FIG. 1
was wound around the outer periphery of the wound conductor. At
this time, the high thermoconductive insulating tape 1 could be wound
irrelevant to either of the mica layer 3, or the high thermoconductive
filler layer 7 is closest to the wound conductor 10, but in the present
embodiment, the high thermoconductive insulating tape 1 was wound
at the outer periphery of the wound conductors 10 so that the mica
layer 3 was to be closest to the wound conductor 10. Subsequently, a
releasing tape 12 was wound around the outer periphery of the high
thermoconductive insulating tape 1. The reason to wind the releasing
tape 12 at the outer periphery of the high thermoconductive insulating
tape 1 is to prevent a shape forming jig, which would be explained
later, from adhering to the high thermoconductive insulating tape 1.
Subsequently, a shape forming jig was attached to the wound
conductor 10 as indicated in FIG. 3, and an external force was applied
from the surface via the jig. Then, the high thermoconductive
insulating film 11 was formed by heating at a designated temperature
for curing the resin 8 in the high thermoconductive insulating tape 1
with removing the fine bubbles contained in the high
thermoconductive insulating tape 1 with a part of the resin 14 in the
high thermoconductive insulating tape 1, and the winding for
electrical machines 9 was obtained.
The windings 9 for electrical machines of the present embodiment
manufactured as above are assembled into core slot of electric rotary
machines such as power generators, motors, and the like.
Figs.4 is a cross sectional view showing a generator and the winding
9 is inserted into slots 50 of the generator. The generator comprises a stator
frame 100 supporting a bearing 20, a stator mounted on the stator frame
100 and a rotor rotatably mounted by the bearing 20 in the stator. The
stator has a stator core 30 and the winding 9 inserted into the slots 50 is
used as a stator coil 40. As shown in Fig.5, the stator coil 40 is assembled
into core slots 50 and fixed by a spring 60 of fibrous glass reinforced plastics
between the slots 50 and stator coil 40. A sheet 70 and spring 90 of fibrous
glass reinforced plastics are sandwitched between a wedge 80 and the stator
to fix the stator winding 40 in the slots 50.
Next, results of tests on the alternating break down voltage of
the windings for electric machines of the present embodiment and of
windings for electric machines of the comparative example are
explained based on Table 1. The windings for electric machines of
the comparative example used in the tests were manufactured with
high thermoconductive insulation formed by high thermoconductive
insulating tape, which was prepared by the following process.
First, a small mica flakes foil 2(weight; 165 g/m2)
manufactured by a paper making machine with small mica flakes
dispersed in water, and a glass cloth 4 (weight; 35 g/m2) were prepared.
A resin composed by mixing BF3 monoethylamine 3 parts by weight
into novolak type epoxy resin 100 parts by weight was impregnated
into the small mica flakes foil 2 and the glass cloth 4, and a small mica
flakes sheet (a laminated body of the mica layer 3 and the
reinforcement layer 5) was obtained by adhering the small mica flakes
foil 2 and the glass cloth 4.
The resin composed by mixing BF3 monoethylamine 3 parts by
weight to the novolak type epoxy resin 100 parts by weight, and
alumina particles were mixed so that a weight ratio of the alumina
particles to the resin became 3.5:1. After adding methylethylketone
of 10 % by weight, the resin was applied onto the side plane of the
reinforcement layer 5 of the small mica flakes sheet by a coater so that
the applied amount of the resin became 230 g/m2. Then, the high
thermoconductive insulating sheet was obtained by evaporating and
removing the methylethylketone.
The high thermoconductive insulating tape 1 was obtained by
slitting the high thermoconductive insulating sheet to 30 mm wide by
a slitter.
The total resin content in the high thermoconductive
insulating tape of the comparative example manufactured as above
was 19. 3 % by weight of the total weight of the high thermoconductive
insulating tape. The resin content in the mica layer was 19. 3 % by
weight of the total weight of the high thermoconductive insulating
tape, and the resin content in the high thermoconductive filler layer
was 10. 4 % by weight of the total weight of the high thermoconductive
insulating tape.
The windings for electrical machines 9 was prepared using the
high thermoconductive insulating tape manufactured as above. The
method of manufacturing was as same as the present embodiment.
Its explanation is omitted.
In the test on the alternating breakdown voltage, an
aluminum foil was wound respectively around the outer periphery of
the windings for electrical machines of the present embodiment and of
the comparative example as an electrode, and the alternating break
down voltages were measured by supplying an alternating voltage
between the aluminum electrode and the winding conductor of each of
windings for electrical machines. The results were as shown in Table
1.
As indicated in Table 1, the windings for electric machines of
the present embodiment had higher alternating break down voltage
than the windings for electric machines of the comparative example.
This was, because the high thermoconductive insulating film of the
winding for electrical machines was formed using the high
thermoconductive insulating tape, wherein the resin content in each of
the mica layer and the high thermoconductive filler layer was specified
to the range of 10-25 % by weight of the total weight of the material,
and because fine bubbles contained in the high thermoconductive
insulating tape could be removed sufficiently with a part of the resin
in the high thermoconductive tape in the pressurizing process during
forming the high thermoconductive insulating film of the windings for
electrical machines.
Accordingly, because the windings for electrical machines of
the present embodiment is provided with a dense high
thermoconductive insulating film superior in electrical characteristics,
a high reliability can be provided to the electric rotary machines
operated with a high voltage.
In accordance with the insulating material relating to the
present invention, the high thermoconductive insulating film superior
in electrical characteristics can be obtained, because the resin content
in each of the mica layer and the high thermoconductive filler layer is
specified to the range of 10-25 % by weight of the total weight of the
material, and fine bubbles contained in the high thermoconductive
insulating tape can be removed sufficiently with a part of the resin in
the high thermoconductive tape in the pressurizing process during
forming the high thermoconductive insulating film of the windings for
electrical machines.
In accordance with the resin content specified as above,
decrease of workability and causing wrinkles to the insulating
material during winding the wound conductors with the insulating
material can be prevented. Therefore, generation of voids in the
insulating film of the windings for electrical machines, which will
cause an electrical defect, can be prevented; and the high
thermoconductive insulating film superior in electrical characteristics
can be obtained.
In accordance with the insulating material relating to the
present invention, the high thermoconductive insulating film superior
in electrical characteristics can be obtained. Because difference of
the resin content in the mica layer from the resin content in the filler
layer is specified equal to 10 % by weight or less, a part of the resin
including fine bubbles therein, which should be removed outside, can
be prevented from entering and remaining into the one layer of
smaller resin content from the other layer of larger resin content.
In accordance with the windings for electrical machines
relating to the present invention, the highly reliable windings for
electrical machines having the insulating film superior in electrical
characteristics, and the electrical characteristics, which will not be
deteriorated even if the windings are used in any electric rotary
machines, can be obtained. Because the insulating film is formed
using the insulating material, wherein the resin content in each of the
mica layer and the high thermoconductive filler layer is specified to
the range of 10-25 % by weight of the total weight of the insulating
material, fine bubbles contained in the high thermoconductive
insulating tape can be removed sufficiently with a part of the resin in
the high thermoconductive tape in the pressurizing process during
forming the high thermoconductive insulating film of the windings for
electrical machines.
If the insulating film is formed using the insulating material,
wherein the resin content is specified to the range as above, decrease
of workability and causing generation of wrinkles to the insulating
material during winding the wound conductors with the insulating
material can be prevented. Therefore, generation of voids in the
insulating film of the windings for electrical machines, which will
cause an electrical defect, can be prevented; and the highly reliable
windings for electrical machines having the high thermoconductive
insulating film superior in electrical characteristics, and the electrical
characteristics, which will not be deteriorated even if the windings are
used in any electric rotary machines, can be obtained.
In accordance with the windings for electrical machines
relating to the present invention, its insulating film is formed using
the insulating material; wherein, because the difference of the resin
content in the mica layer from the resin content in the filler layer is
specified equal to 10 % by weight or less, a part of the resin including
fine bubbles therein, which should be removed outside, can be
prevented from entering and remaining into the one layer of smaller
resin content from the other layer of larger resin content; and the
highly reliable windings for electrical machines having the high
thermoconductive insulating film superior in electrical characteristics,
and the electrical characteristics, which will not be deteriorated even
if the windings are used in any electric rotary machines, can be
obtained.
We Claims
1. An insulating material comprising a mica layer (3), a
reinforcement layer/and a filler layer/wherein the resin content in
respective of said mica layer and said filler layer is in the range of
10-25 % by weight, respectively, of the total weight of said insulating
material.
2. An insulating material as claimed in claim 1, wherein the
resin content in said mica layer differs from the resin content in said
filler layer by 10 % by weight or less.
3. An insulating material as claimed in claim 1, wherein the

resin content in the mica layer and filler layer is substantially equal to
each other.
4. An insulating material as claimed in claim 1, wherein the
total resin content in said insulating material is in the range of 20-
50 % by weight of the total weight of said insulating material.
5. An insulating material as claimed in claim 1, wherein said
filler layer comprises a filler material having a thermal conductivity
of at least 5 W/m.K.
6. A winding for electrical machines comprising a high
dielectric strength layer, a reinforcement layer, and a
thermoconductive layer; wherein a resin content in respective of said
high dielectric strength layer and said thermoconductive layer is in
the range of 10-25 % by weight, respectively, of total weight of its
insulating material; and insulating film is formed so that said high
dielectric strength layer of said insulating material is placed closer to
a wound conductor than said thermoconductive layer and said
reinforcement layer.
7. A winding for electrical machines comprising a high
dielectric strength layer, a reinforcement layer, and a
thermoconductive layer; wherein a resin content in respective of said
high dielectric strength layer and said thermoconductive layer is in
the range of 10-25 % by weight, respectively, of total weight of its
insulating material; and insulating film is formed so that said
thermoconductive layer of said insulating material is placed closer to
a wound conductor than said high dielectric strength layer and said
reinforcement layer.
8. A winding for electrical machines comprising an insulating
film, which comprises a high dielectric strength layer, a
reinforcement layer, and a thermal conductive layer; wherein an
alternating insulation breakdown voltage of said insulating film is set
in the range of 26.5 -29.0 kV/mm by adjusting the resin content in
respective of said high dielectric strength layer and said thermal
conductive layer.
9. A winding for electrical machines comprising an insulating

film composed of an insulating material, which comprises a mica
layer, a reinforcement layer, and a filler layer; wherein a rosin
content in respective of said mica layer and said filler layer is in the
range of 10-25 % by weight, respectively, of total weight of its
insulating material.
10. A winding for electrical machines as claimed in claim 8,
wherein the resin content in said mica layer differs from the resin
content in said filler layer by 10 % by weight or less.
11. A winding for electrical machines as claimed in claim 9,
wherein the total resin content in said insulating material is in the
range of 20-50 % by weight of the total weight of said insulating film.
12. A winding for electrical machines as claimed in claim 9,
wherein said filler layer of said insulating material comprises a filler
material having a thermal conductivity of at least: 5 W/m • K.
13. An electric rotary machine provided with a winding for
Electrical machines as claimed in any one of claim 5 to claim 11.
14. An insulating material comprising:
a reinforcement layer having two surfaces ;
a mica layer formed on one surface of said reinforcement layer/?
and
a filler layer formed on the other surface of said reinforcement
layer after lamination of said reinforcement layer and mica layer.
wherein the resin content in respective of said mica layer and sai'd
filler layer is in the range of 10-25 % by weight, respectively, of the
total weight of said insulating material.
15. An insulating material comprising:
a reinforcement layer having two surfaces :
a mica layer formed on one surface of said reinforcement layer:
and
a filler layer formed on said mica layer after lamination of sai.l
reinforcement layer and mica layer, wherein the resin content m
respective of said mica layer and said filler layer is in the range of
10-25% by weight, respectively, of the total weight
of said insulating material.

The high thermoconductive insulating film 11 was formed around the outer periphery of the wound conductors 10, using the high thermoconductive insulating tape 1 comprising the mica layer 3, the reinforcement layer 5, and the high thermoconductive filler layer 7, wherein the resin content in each layer of the mica layer 3 and the high thermoconductive filler layer 7 is specified to the range of 10-25 % by weight of the total weight of the material.