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EP 3 007 190 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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20.05.2020 Bulletin 2020/21 |
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Date of filing: 09.10.2014 |
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International Patent Classification (IPC):
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Pre-product for a dry transformer high voltage coil
Vorprodukt für eine Trockentransformatorhochspannungsspule
Pré-produit pour bobine haute tension de transformateur à sec
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Designated Contracting States: |
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AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL
NO PL PT RO RS SE SI SK SM TR |
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Date of publication of application: |
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13.04.2016 Bulletin 2016/15 |
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Proprietor: ABB Power Grids Switzerland AG |
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5400 Baden (CH) |
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Inventors: |
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- Weber, Benjamin
59955 Winterberg (DE)
- Tepper, Jens
59929 Brilon (DE)
- Zillmann, Karl-Heinz
34431 Marsberg (DE)
- Soetebier, Sven
59929 Brilon (DE)
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Representative: Wesch, Arno et al |
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Reble & Klose
Rechts- und Patentanwälte
Konrad-Zuse-Ring 32 68163 Mannheim 68163 Mannheim (DE) |
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References cited: :
EP-A1- 0 012 542 EP-A2- 0 336 053 US-A1- 2011 291 791
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EP-A1- 0 150 921 US-A- 3 263 196
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] The invention is related to
a method for manufacturing a dry transformer high voltage coil according to the preamble
of claim 1.
[0002] US 3,263,196 A shows such a method, namely a method of construction of encapsulated electrical coils
for stationary induction apparatus. EP 0 012 542 A1 discloses a method of making heat curable adhesive coated insulation for transformers.
A resin system may contain pigments for coloring.
[0003] It is known that coils for dry transformers in high voltage applications, for example
with a rated voltage in the range of 6kV to 36kV, comprise an electrical conductor,
which is wound layer wise in radially adjacent layers around a winding axis. The axial
winding direction typically changes inbetween radially adjacent winding layers so
that a meander-like winding scheme is gained. Thus during operation of such a coil
a voltage difference inbetween adjacent layers occurs, which is lowest, at this axial
end of a layer, where the conductor is fed up to the radially above laying layer and
which is highest at the axial opposite end of the respective layer.
[0004] In order to avoid any electrical breakdown inbetween adjacent layers during operation
of the coil, it is usual to provide an additional laminar insulation layer inbetween.
This is for example made from a band-like wound prepreg material. Prepreg is a resin
impregnated band material wherein the resin is in B-stage. So the resin respectively
the band material is of harder consistency, wherein it has to become transferred to
its final stage by a curing process at for example 150°C - 170°C. During this curing
process the resin is melting back into a liquid state again and solidifies into a
crystalline structure with extremely hard consistency. So an interim insulation layer
is transformed to a final insulation layer by a curing process.
[0005] In order to improve the insulation ability of such an additional insulation layer
the number of voids respectively cavities, which are not filled with resin, has to
be reduced as much as possible to avoid partial discharge.
[0006] Disadvantageously within the state of the art is that a wound interim insulation
layer typically comprises several voids especially in the wedge-shaped areas inbetween
adjacent conductors within the same layer. Thus during the curing process there is
not sufficient melted resin for filling the whole space inbetween the wound conductors
and the quality of the final insulation layer is reduced therewith.
[0007] It is objective of the invention to provide a pre-product for a dry transformer high
voltage coil with interim laminar insulation layer inbetween adjacent layers of conductors,
which affords the manufacturing of a dry transformer high voltage coil with improved
insulation layer by a curing process.
[0008] The problem is solved by a
method according to claim 1.
[0009] The amount of voids is reduced by providing outer insulation layers with a soft consistency.
So the conductor loops which are wound on an outer layer with soft consistency are
embedded therein, preferably with half of their diameter. Due to the embedding also
the wedge shaped areas inbetween the conductors are filled with the material of soft
consistency in an advantageous way. After curing the soft material it will be of hard
consistency and suitable insulation material for the insulation layer of the coil.
[0010] In order to ensure an electrically required minimum insulation thickness inbetween
radially adjacent layers of conductors the interim laminar insulation layer comprises
an inner insulation layer of hard consistency which is not considerably caveable so
that its thickness is not reduced by the winding process whilst that a radial pressure
is applied. An outer insulation layer of soft consistency is foreseen on both sides
of the inner layer so that as well conductors which are under the interim insulation
layer as conductors which are above the interim insulation layers are embedded therein.
[0011] Thus the number of voids in the interim insulation layer of the pre-product for a
coil is reduced in an advantageous way and the number of voids in the cured final
insulation layer therewith. The insulation ability of such a layer is improved in
an advantageous way.
[0012] The consistency of the material of the inner insulation layer is as hard, that its
thickness profile is not considerably caved while winding the adjacent layer of electrical
conductors thereon during manufacturing process. An electrically required minimum
insulation thickness inbetween adjacent layer of conductors is ensured therewith.
Dependent on the electrical requirements it can be useful to adapt the thickness of
the inner insulation layer along the axial length of the coil so that a wedge shaped
cross section of the insulation layer is formed.
[0013] The consistency of the material of the outer insulation layers is as soft that its
thickness profile is nearly form-locking caved while the adjacent layer of conductors
are wound thereon during manufacturing process. The coil is manufactured from the
radial inner layers of conductors respectively insulation to the radial outer layers.
So a layer of conductors is embedded into an outer insulation layer and afterwards
an outer insulation layer is applied on the layer of conductors. In the ideal case
each loop of the layer of conductors is totally embedded in outer insulation layers
so that no voids are present in the interim insulation layer.
[0014] The inner insulation layer comprises a foil. A foil has the advantage, that it has
a constant thickness and is as hard, that the thickness is not significantly reduced
when a pressure is applied thereon. A constant thickness even under pressure conditions
affords a minimum insulation ability of the whole insulation layer. A suitable material
for the foil is for example Kapton or PE wherein a suitable thickness is in the range
of 100 µm to 3.5mm.
[0015] The foil may be covered with a coating that glues the single layers of the interim
insulation layer together during the curing process. In contrast to resin a foil will
not be molten during a curing process. Thus it has to be ensured, that a void-free
adhesion of the foil with the both adjacent outer layers is gained. A suitable material
for glue is for example resin-based, preferably resin in 'B' stage, what means, that
it is in a flexible solid state wherein after remelting the resin in 'B' stage by
a curing process a hardening process is initiated. Prepreg is a band-like material
with resin in the 'B' stage.
[0016] The outer insulation layers may have a varying thickness profile corresponding roughly
to the outer shape of the layer of conductors to be embedded therein. The cross section
of a typical electrical conductor is round so that a helical wedge-shaped area inbetween
adjacent loops of conductors is built. Accordingly the shape of the not yet impressed
outer insulation layer is thicker in the helical wedge-shaped area. In this case the
deformation of the outer insulation layer is not as high if the layer of conductors
is wound thereon.
[0017] The outer insulation layers may comprise a resin impregnateable and/or resin impregnated
material. In order to reduce the number of voids within the insulation material the
resin is in the liquid state wherein the resin might become applied during the winding
process of the transformer coil or shortly before.
[0018] The outer insulation layers comprise polyester felt. This is a material with a sufficient
soft consistency which additionally has the ability to suck up liquid resin like a
sponge. Thus the number of voids in the outer insulation layer is reduced in an advantageous
way.
[0019] According to the invention, the resin impregnateable material respectively the polyester
felt is of different color than the resin for impregnation. This facilitates an optical
control of the quality of impregnation of the polyester felt. In case that the Polyester
felt is of white color and the resin is of black color the impregnated and not impressed
polyester felt would be of dark grey color. Any areas of poor impregnation would be
white or light gray. Of course also other combinations of colors with a preferably
high contrast are suitable.
[0020] According to another embodiment of the invention the interim laminar insulation layer
has been impregnated at least in part during applying it on the layer of electrical
conductors thereunder. Thus it is ensured that potential voids in the edge are of
inner and outer insulation layers for example are completely filled with liquid resin.
In case that there is more resin than voids to be filled the dispensable resin is
remaining on the surface of the coil for impregnating further layers which will be
applied thereon.
[0021] The problem is solved by a method for manufacturing a dry transformer high voltage
coil, comprising the step of applying heat on a pre-product for a dry transformer
high voltage coil. During such a curing process a temperature of for example 200°C
is applied for 2 hours so that the resin can be completely hardened therewith. After
the curing process the formally soft outer insulation layer and the inner layer are
combined to a consistent insulation layer of hard consistency.
[0022] A dry transformer high voltage coil has been manufactured according to the aforementioned
method of the invention. Thus the quality of the insulation layers is improved by
reducing the number of voids therein.
[0023] Further advantageous embodiments of the invention are mentioned in the dependent
claims.
[0024] The invention will now be further explained by means of an exemplary embodiment and
with reference to the accompanying drawings, in which:
- Figure 1
- shows an exemplary pre-product for a dry transformer high voltage coil in 1 st stage,
- Figure 2
- shows an exemplary pre-product for a dry transformer high voltage coil in 2nd stage,
- Figure 3
- shows an exemplary pre-product for a dry transformer high voltage coil in 3rd stage,
- Figure 4
- shows an exemplary pre-product for a dry transformer high voltage coil in 4th stage,
- Figure 5
- shows an exemplary pre-product for a dry transformer high voltage coil in 5th stage,
- Figure 6
- shows an exemplary pre-product for a dry transformer high voltage coil in 6th stage,
- Figure 7
- shows an exemplary pre-product for a dry transformer high voltage coil in final stage,
- Figure 8
- shows an exemplary dry transformer high voltage coil
[0025] Figure 1 shows an exemplary pre-product for a dry transformer high voltage coil in
1st stage of its production in a sketch 10. A layer 12 of conductor loops 14, 16,
18 is spirally wound around a winding axis 22 on a bobbin 22.
[0026] Figure 2 shows an exemplary pre-product for a dry transformer high voltage coil in
2nd stage of its production in a sketch 30. Here an outer insulation layer 32 of soft
consistency, in this case strip-shaped polyester felt, has been wound around the layer
of conductors. Since the material of the outer insulation layer 32 is soft, the outer
shape of the layer of conductors is caved therein.
[0027] Figure 3 shows an exemplary pre-product for a dry transformer high voltage coil in
3rd stage of its production in a sketch 40. Here the outer insulation layer 42 has
been impregnated with a liquid resin also in the wedged areas inbetween the loops
of conductors.
[0028] Figure 4 shows an exemplary pre-product for a dry transformer high voltage coil in
4
th stage of its production in a sketch 50. Here an inner insulation layer 52, in this
case a polyester foil, has been applied on the impregnated outer insulation layer.
[0029] Figure 5 shows an exemplary pre-product for a dry transformer high voltage coil in
5
th stage of its production in a sketch 60. An outer insulation 62 layer from polyester
felt has been applied on the inner insulation layer.
[0030] Figure 6 shows an exemplary pre-product for a dry transformer high voltage coil in
6
th stage of its production in a sketch 70. The outer insulation layer 72 from polyester
felt has been impregnated with liquid resin.
[0031] Figure 7 shows an exemplary pre-product for a dry transformer high voltage coil in
final stage of its production in a sketch
90. Here a second layer 94 of conductors has been wound around the insulation layer and
the first layer 92 of conductors below. Of course a real coil might comprise significant
more layers of electrical conductors and insulation layers inbetween.
[0032] Figure 8 shows an exemplary dry transformer high voltage coil in a sketch 100. Due
to a curing process the interim insulation layer with its inner and two outer insulation
layers is now converted into a consistent solid final insulation layer 102.
List of reference signs
[0033]
- 10
- exemplary pre-product for a dry transformer high voltage coil in 1st stage
- 12
- fist layer of wound electrical conductors
- 14
- first conductor loop of first layer
- 16
- second conductor loop of first layer
- 18
- third conductor loop of first layer
- 20
- bobbin
- 22
- axis of rotation
- 30
- exemplary pre-product for a dry transformer high voltage coil in 2nd stage
- 32
- outer insulation layer
- 40
- exemplary pre-product for a dry transformer high voltage coil in 3rd stage
- 42
- outer insulation layer impregnated with resin
- 50
- exemplary pre-product for a dry transformer high voltage coil in 4th stage
- 52
- inner insulation layer
- 60
- exemplary pre-product for a dry transformer high voltage coil in 5th stage
- 62
- outer insulation layer
- 70
- exemplary pre-product for a dry transformer high voltage coil in 6th stage
- 72
- interim insulation layer
- 74
- outer insulation layer
- 76
- inner insulation layer
- 78
- outer insulation layer
- 90
- exemplary pre-product for a dry transformer high voltage coil in final stage
- 92
- fist layer of wound electrical conductors
- 94
- second layer of wound electrical conductors
- 100
- exemplary dry transformer high voltage coil
- 102
- final insulation layer
1. Method for manufacturing a dry transformer high voltage coil comprising the step of
applying heat on a pre-product for a dry transformer high voltage coil, comprising
at least two radially adjacent layers (12, 92, 94) of a wound electrical conductor
(14, 16, 18) with an interim laminar insulation layer (72) inbetween, wherein the
interim insulation layer (72) is foreseen to be transformed to a final insulation
layer (102) by curing process, wherein the interim insulation layer (72) comprises
an inner (76) and two outer (32, 42, 62) insulation layers, wherefrom the inner one
(76) is of hard consistency and the outer ones (32, 42, 62) are of soft consistency,
wherein the inner insulation layer (76) comprises a foil, wherein the consistency
of the material of the inner insulation layer (76) is as hard, that its thickness
profile is not considerably caved while winding the adjacent layer (12, 92, 94) of
electrical conductors (14, 16, 18) thereon during manufacturing process, wherein the
consistency of the material of the outer insulation layers (32, 42, 62) is as soft
that its thickness profile is nearly form-locking caved while winding the adjacent
layer (12, 92, 94) of conductors (14, 16, 18) thereon during manufacturing process
and wherein the outer insulation layers (32, 42, 62) comprise a resin impregnateable
material,
characterized in that
the outer insulation layers (32, 42, 62) have been impregnated with resin, wherein
the resin impregnateable material is a polyester felt which is of different color
than the impregnating resin, wherein a combination of colors with high contrast is
used to facilitate an optical control of the quality of impregnation of the polyester
felt.
2. Method according to claim 1, characterized in that the foil is covered with a coating that glues the interim insulation layer (72) together
during the curing process.
3. Method according to any of the previous claims, characterized in that the outer insulation layers (32, 42, 62) have a varying thickness profile corresponding
roughly to the outer shape of the layer (12, 92, 94) of conductors (14, 16, 18) to
be embedded therein.
4. Method according to one of the previous claims, characterized in that the interim laminar insulation layer (72) has been impregnated at least in part during
applying it on the layer (12, 92, 94) of electrical conductors (14, 16, 18) thereunder.
1. Verfahren zum Herstellen einer Trockentransformator-Hochspannungsspule, umfassend
den Schritt des Anwendens von Wärme auf ein Vorprodukt für eine Trockentransformator-Hochspannungsspule,
umfassend mindestens zwei radial benachbarte Schichten (12, 92, 94) eines gewickelten
elektrischen Leiters (14, 16, 18) mit einer vorläufigen laminaren Isolationsschicht
(72) dazwischen, wobei die vorläufige Isolationsschicht (72) dazu vorgesehen ist,
durch einen Aushärtungsprozess in eine endgültige Isolationsschicht (102) umgewandelt
zu werden, wobei die vorläufige Isolationsschicht (72) eine innere (76) und zwei äußere
(32, 42, 62) Isolationsschichten umfasst, von denen die innere (76) eine harte Konsistenz
aufweist und die äußeren (32, 42, 62) eine weiche Konsistenz aufweisen, wobei die
innere Isolationsschicht (76) eine Folie umfasst, wobei die Konsistenz des Materials
der inneren Isolationsschicht (76) so hart ist, dass ihr Dickenprofil nicht wesentlich
nachgibt, wenn während des Herstellungsprozesses die benachbarte Schicht (12, 92,
94) elektrischer Leiter (14, 16, 18) darauf gewickelt wird, wobei die Konsistenz des
Materials der äußeren Isolationsschichten (32, 42, 62) so weich ist, dass ihr Dickenprofil
nahezu formschlüssig nachgibt, wenn während des Herstellungsprozesses die benachbarte
Schicht (12, 92, 94) von Leitern (14, 16, 18) darauf gewickelt wird, und wobei die
äußeren Isolationsschichten (32, 42, 62) ein mit Harz imprägnierbares Material umfassen,
dadurch gekennzeichnet, dass
die äußeren Isolationsschichten (32, 42, 62) mit Harz imprägniert wurden, wobei es
sich bei dem mit Harz imprägnierbaren Material um ein Polyesterfilz handelt, das eine
andere Farbe als das Imprägnierharz aufweist, wobei eine Kombination aus Farben mit
hohem Kontrast verwendet wird, um eine optische Kontrolle der Imprägnierungsqualität
des Polyesterfilzes zu erleichtern.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Folie mit einer Beschichtung bedeckt ist, die die vorläufige Isolationsschicht
(72) während des Aushärtungsprozesses zusammenklebt.
3. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die äußeren Isolationsschichten (32, 42, 62) ein variierendes Dickenprofil aufweisen,
das etwa der äußeren Form der Schicht (12, 92, 94) von darin einzubettenden Leitern
(14, 16, 18) entspricht.
4. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die vorläufige laminare Isolationsschicht (72) zumindest teilweise während ihres
Aufbringens auf die Schicht (12, 92, 94) elektrischer Leiter (14, 16, 18) darunter
imprägniert wurde.
1. Procédé de fabrication d'une bobine haute tension de transformateur non immergé comprenant
l'étape consistant à appliquer de la chaleur sur un préproduit d'une bobine haute
tension de transformateur non immergé, comprenant au moins deux couches adjacentes
radialement (12,92,94) d'un conducteur électrique enroulé (14, 16, 18) entre lesquelles
se trouve une couche d'isolation laminaire intermédiaire (72), dans lequel la couche
d'isolation intermédiaire (72) est prévue pour être transformée en une couche d'isolation
finale (102) par un processus de durcissement, dans lequel la couche d'isolation intermédiaire
(72) comprend une couche d'isolation interne (76) et deux couches d'isolation externes
(32, 42, 62), la couche interne (76) étant de consistance dure et les couches externes
(32, 42, 62) étant de consistance souple, dans lequel la couche d'isolation interne
(76) comprend une feuille, dans lequel la consistance du matériau de la couche d'isolation
interne (76) est tellement dure que son profil d'épaisseur n'est pas considérablement
creusé pendant l'enroulement de la couche adjacente (12, 92, 94) de conducteurs électriques
(14, 16, 18) sur celle-ci pendant le processus de fabrication, dans lequel la consistance
du matériau des couches d'isolation externes (32, 42, 62) est tellement souple que
son profil d'épaisseur est pratiquement creusé de manière emboîtante pendant l'enroulement
de la couche adjacente (12, 92, 94) de conducteurs (14, 16, 18) sur celle-ci pendant
le processus de fabrication et dans lequel les couches d'isolation externes (32, 42,
62) comprennent un matériau pouvant être imprégné d'une résine,
caractérisé en ce que
les couches d'isolation externes (32, 42, 62) ont été imprégnées d'une résine, dans
lequel le matériau pouvant être imprégné d'une résine est un feutre en polyester qui
est d'une couleur différente de celle de la résine imprégnée, dans lequel une combinaison
de couleurs ayant un contraste élevé est utilisée pour faciliter une commande optique
de la qualité d'imprégnation du feutre en polyester.
2. Procédé selon la revendication 1, caractérisé en ce que la feuille est couverte d'un revêtement qui colle la couche d'isolation intermédiaire
(72) ensemble pendant le processus de durcissement.
3. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que les couches d'isolation externes (32, 42, 62) ont un profil d'épaisseur variable
correspondant grossièrement à la forme externe de la couche (12, 92, 94) de conducteurs
(14, 16, 18) devant être incluse en son sein.
4. Procédé selon l'une des revendications précédentes, caractérisé en ce que la couche d'isolation laminaire intermédiaire (72) a été imprégnée au moins en partie
pendant son application sur la couche (12, 92, 94) de conducteurs électriques (14,
16, 18) en dessous.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only.
It does not form part of the European patent document. Even though great care has
been taken in compiling the references, errors or omissions cannot be excluded and
the EPO disclaims all liability in this regard.
Patent documents cited in the description