EP2442323A1 - Oil transformer isolation module - Google Patents

Abstract

The module (40) has disc-like insulating elements (44) interconnected along a line (42). The insulation element has one plane arranged parallel to another plane. A corrugated sheet is arranged between the planes. The corrugated sheet is formed with lateral edges so as to be crimped between the planes. The corrugated sheet is formed with cavities flooded with liquid.

Description

The invention relates to a Öltransformatorenisolationsmodul with a plurality of along a line flush superimposed, interconnected, similar, disk-like insulation elements each having a similar floor plan.

It is well known that transformers having a rated power of, for example, 100 MVA and higher at a rated voltage of 110 kV and higher are usually designed as oil transformers, which may have a weight of up to 200 t. In this case, the transformer is arranged inside an oil-filled transformer tank, wherein the oil serves both the insulation and the improved cooling. The electrical connection of the respective terminals of the transformer with Ausleitungsisolatoren on the outside of the oil boiler takes place here by electrical conductors which are optionally surrounded by a barrier system. A barrier system is constructed radially symmetrical about the respective conductor and comprises an electrically conductive shielding tube and, if necessary, a plurality of spaced apart isolation barriers.

For reasons of mechanical stability, the conductors or the tube-like barrier systems are to be supported at certain intervals within the oil boiler. For this purpose, if necessary, use post insulators, which are made for example the material pressboard. The isolation ability of a massive Support insulator is usually less than the isolation capability of pure oil with identical isolation distance because of the additional burden of creepage distances.

The disadvantage, therefore, is that a required isolation distance in the region of a post insulator is higher than if the conductor or the barrier system were floating freely in the oil, so that the oil quota is to be made larger than absolutely necessary. In addition, oil transformers greater performance and voltage are unique or are made only in very small batches, so that there are also a variety of geometric requirements for the support insulators, which leads to an undesirable variety of variants, which ultimately requires increased production costs.

Based on this prior art, it is an object of the invention to provide a Öltransformatorenisolationsmodul or a support insulator for use in an oil-filled environment such as an oil boiler, which has improved insulation and also is easy to manufacture in a wide variety of variants.

This object is achieved by an oil transformer insulation module of the aforementioned type. This is characterized in that an insulation element has at least a first planar and a second thereto adjacent and predominantly parallel layer of a mechanically strong, flat first insulation material that the first and the second layer Insulating material with a third interposed, corrugated layer of a mechanically strong, flat, second insulating material are connected and spaced, wherein the third layer has lateral edges and is corrugated such that all cavities formed by the corrugated shape over the lateral edges complete with a Liquid are floatable.

The basic idea of the invention is to use a support structure with cavities instead of a solid post insulator, for example made of pressboard or ceramic, which are completely filled with oil during operation of the transformer. The support structure is preferably made of the material pressboard. Any path along a surface normal defining the shortest strike path through an oil transformer isolation module thus formed is not exclusive in solid insulating material, but the cavities are configured by the waveform of the third layers of the respective insulation elements such that always a part of the path also passes through oil. Due to the different insulating capabilities of oil and solid insulating material such as pressboard in combination with their different dielectric constants, this results in a higher overall insulation capacity of the entire arrangement. The effect of the displacement of the electric field due to the higher permittivity of a solid insulating material such as press chip in adjacent oil channels, such as exist between the barriers to be supported diversion is drastically reduced compared to massive structures by an oil content of the insulation section in the support insulator according to the invention. The proportion of oil is according to a preferred variant in a range of 40% to 60%, more preferably the range is around 50%.

A purely solid insulating material path follows in a Öltransformatorenisolationsmodul invention partially the waveform of the third layer of each insulating element and is therefore obliquely sections and compared to the shortest path along a surface normal correspondingly longer, so that also results in this respect improved isolation.

However, a prerequisite for an insulating capability of an oil transformer isolation module according to the invention during operation is that its cavities are completely flooded with oil and air pockets are avoided. For this purpose, all cavities are to be designed so that they are floodable at least from one, preferably from two sides. Of course, it is also possible to use another suitable liquid insulating agent instead of the proven liquid insulating agent oil. A flooding of an oil transformer insulation module or an insulation element with oil takes place through its open side edges, into which the cavities formed by the corrugated third layers open, so to speak, as channels. By drawing a vacuum, it is possible to remove possible air pockets particularly reliably from horizontally arranged channels formed by cavities.

In order to ensure a mechanical stability of an oil transformer insulation module or of this at least partially forming insulation elements is the use of a mechanically strong insulation material for the respective layers necessary. Here, especially in combination with the insulating agent oil, the insulation material Pressspan or another correspondingly hard material based on cellulose proven. Completely unsuitable, however, is a soft pulp material such as cardboard. In the composite of the first to third layers thus results in a high mechanical stability of an oil transformer insulation module, as well as in the overall composite of all stacked insulation elements. According to the invention, an oil transformer insulation module is to be stressed highest along the line with an electrical voltage along which the insulation elements are arranged one above the other.

The modular structure of a plurality of stacked, interconnected, similar, disk-like insulation elements allows for easy production of different Stützisolatorvarianten. Thus, it is preferable to first produce a larger plate of a three-layer composite material, for example with an edge length of 1 m by 1 m. Subsequently, the desired variety of insulation elements in a desired floor plan form, for example, 15cm by 15cm edge length, cut out or cut out. These insulation elements are then to be arranged one above the other, for example by means of an adhesive connection. Thus, an oil transformer insulation module or a support insulator is provided with improved insulation property, which is particularly easy to manufacture in a wide variety of variants.

In a particularly preferred embodiment of the oil transformer insulation module according to the invention, the respective third layer of the insulation elements is at least partially corrugated trapezoidal. This provides an improved surface connectivity of the formed by the trapezoidal shape plateaus of the third corrugated layers with the adjacent planar first and second layers, which also also has a positive effect on the insulating ability of the insulating element. In addition, the mechanical stability is advantageously increased by the now approximately straight strut shape of the trapezoidal sides between each first and third layer.

According to a further embodiment variant of an oil transformer insulation module according to the invention at least one further level position and an associated further corrugated position are at least one insulating element between the first and second layer arranged so that there is an alternating sequence of planar and wavy layers. This multilayer structure advantageously increases both the electrical insulation capability and the mechanical stability.

According to a further embodiment, the first insulating material corresponds to the second insulating material, apart from the waveform. This simplifies the manufacture of an oil transformer isolation module. Differences in the insulating material could be due, for example, in its thickness, for example 1 mm to 4 mm, or in its flexibility, wherein pressboard variants are each a preferred embodiment.

In a particularly preferred embodiment variant, the height of the cavities formed by the corrugated shape corresponds to at least twice the thickness of the non-corrugated second insulation material, wherein a four- or six-fold thickness may well be suitable. This ensures that each running along a surface normal through the Öltransformatoren Isolationsmodul insulation path to a minimum proportion of oil, whereby the isolation capability is advantageously increased.

According to a particularly preferred form of the oil transformer insulation module, the lateral edges of a corrugated layer are offset on all sides relative to the edges of the adjacent planar layers, so that a circumferential first groove is formed, which advantageously extends the creepage path and increases the insulating capacity of the insulation element becomes.

According to a further embodiment variant of the oil transformer isolation module according to the invention, an intermediate layer with a similar plan of a solid insulating material is arranged between at least two insulation elements arranged one above the other. This can be useful if, for example, only a smaller improvement of the isolation capability is required. As a particularly preferred sub-variant thereof, the intermediate layer has a floor plan which is larger than the respective floor plan of the adjacent insulation elements, so that a circumferential projection is formed by the intermediate layer. This also extends the creepage path and thus improves the insulation ability. The same effect is also achieved in that the intermediate layer has a floor plan which is smaller than the respective floor plan of the adjacent insulation modules, so that by the intermediate layer, a circumferential second groove is formed, which is directed inwards.

A suitable adhesive for bonding adjacent layers of an insulating element, or for connecting insulating elements with each other or with an intermediate layer is high-voltage-resistant adhesive such as casein. This preferably dries under elevated pressure and at elevated temperature, so as to ensure a desired stable compound in the dried state.

During operation of an oil transformer insulation module, all cavities formed by the corrugated shape of the third layers of the insulation elements are completely flooded with oil. According to the invention, its desired insulation capability is achieved by an oil transformer insulation module or its insulation elements only when all the cavities are filled with oil or another suitable liquid insulation agent.

An oil transformer with oil tank and at least one Öltransformatorenisolationsmodul invention can thus be manufactured in a particularly advantageous manner with a slightly smaller oil tank.

Further advantageous embodiment possibilities can be found in the further dependent claims.

Reference to the embodiments illustrated in the drawings, the invention, further embodiments and other advantages will be described in detail.

Fig. 1

einen Schnitt durch ein Teil eines ölgefüllten Isolationselementes,

Fig. 2

eine Seitenansicht auf ein erstes exemplarisches Öltransformatorisolationsmodul,

Fig. 3

eine Seitenansicht auf zweites exemplarisches Öltransformatorisolationsmodul sowie

Fig. 4

eine Draufsicht auf verschiedene Grundrisse.

Show it:

Fig. 1

a section through a part of an oil-filled insulation element,

Fig. 2

a side view of a first exemplary oil transformer isolation module,

Fig. 3

a side view of the second exemplary oil transformer isolation module as well

Fig. 4

a plan view of different floor plans.

Fig. 1 shows a section 10 through a portion of an oil-filled insulation element. A first planar layer 12 of a first insulating material is connected at a plurality of connection points, one of which is designated by the reference numeral 22, with a third corrugated layer 16 of a second insulating material. The other side of the third corrugated layer 16 is connected to a second planar layer 14 of a first insulating material at further connection points 24, so that between the flat layers 12, 14 and the corrugated layer 16 cavities 18, 20 are formed, which in FIG. are indicated as filled with oil 26. These are open at the lateral edges of the insulation element and have a channel-like shape. This ensures that each channel via the lateral edges with a liquid insulation medium, in this example oil 26, is floatable. An insulation element has only its full electrical insulation capability, if all the cavities are completely filled with a corresponding liquid insulation medium and no air-filled areas are no longer available. Material materials of pressboard or other stable pulp material are particularly suitable as insulating materials, wherein the thickness of a respective first or second layer may be for example 2mm to 5mm and the thickness of a corrugated third layer, for example 10mm to 20mm, the latter being an actual material thickness 30 and a height 28 of a respective cavity 18, 20 composed. In non-oil-filled state, this structure is particularly lightweight, so that such a module compared to a solid insulator, for example, when mounting in an oil tank of an oil transformer to be manufactured is particularly easy to handle.

Due to a trapezoidal shape of the corrugated layer 16 is a two-dimensional contacting 22, 24 of the first 12 and second 14 layer allows the third layer 16 at the thus flattened surfaces, which in comparison to a sinusoidal waveform due to the larger contact surface both positive on the mechanical Stability of the insulation element as well as on its isolation ability. The oblique connecting web formed by the trapezoidal shape namely runs at a fixed angle to the first layer 12 and not as at a sinusoidal at any acute angle through which the adjacent channel-like cavities 18, 20 in the joint area corresponding pointed and heavy with oil to fill, which has both a negative effect on the insulation capacity. The connection points 22, 24 can be realized for example with a suitable high-voltage resistant adhesive such as casein.

Fig. 2 FIG. 12 shows a side view 40 of a first exemplary oil transformer isolation module having a plurality of similar isolation elements 44 aligned flush with one another along a line 42. Between two axially adjacent insulation elements 44, a first intermediate layer 46 made of a solid insulating material is arranged, each having a similar thickness as the insulation elements, for example 1 cm or 2 cm. The connection between insulation elements 44 and intermediate layers 46 via a cured high voltage resistant adhesive. Also for the material of the intermediate layers 46 offers a press chip variant.

The intermediate layers 46 have a smaller floor plan than the plan view of the respective insulation elements 44, so that in each case a transverse to the line 42 aligned circumferential second groove 50 is pronounced, which advantageously extends the creepage along the line 42. By resetting the respective corrugated layers of the insulation elements with respect to their adjacent first and second layers, by which the floor plan of an insulation element is determined, in each case a first circumferential groove 48 is formed, which extends the creepage path again. An intermediate layer 46 may in turn also be formed from a plurality of interconnected planar layers of one or even different insulating materials, as indicated in the figure.

Fig. 3 shows a side view 60 of the second exemplary oil transformer isolation module. This essentially corresponds to the one in Fig. 2 shown Öltransformatorenisolationsmodul, thus has stacked insulation elements 66 and interposed intermediate layers 62, but here have the respective Intermediate layers 62 have a larger ground plan, as the insulation elements 66, so that in each case a circumferential projection 64 is formed, through which the creepage path is also advantageously extended. Another creepage distance extension by first grooves formed by respectively resetting the respective corrugated layers is also realized in the oil transformer isolation module shown, but not provided with corresponding reference numerals.

Fig. 4 shows an exemplary plan view of various layouts of an oil transformer Isolationsmoduls according to the side view in Fig. 3 , The floor plans are similar in shape, but have different cross sections. Shown by reference numeral 72 is a plan view of an exemplary isolation element, for example 12cm by 12cm edge length. This in turn is determined by the floor plan of the first and third layers of the insulation element. The plan view of the enclosed by the two planar layers of an insulating element corrugated and inwardly recessed position is indicated by the reference numeral 74. The resulting from the reset circumferential first groove is indicated by the reference numeral 80. Similarly, reference numeral 76 shows the outline of an intermediate layer 76 having a projection 78 which also extends the creepage path.

LIST OF REFERENCE NUMBERS

10

Section through a part of an oil-filled insulation element

12

first level location

14

second level location

16

third wavy position

18

first cavity

20

second cavity

22

first connection point

24

second connection point

26

oil

28

Height of a cavity

30

Thickness of the second insulation material

40

Side view on first exemplary oil transformer insulation module

42

line

44

similar, disc-like insulation element

46

first intermediate layer

48

circumferential first groove

50

circumferential second groove

60

Side view of second exemplary oil transformer isolation module

62

second intermediate layer

64

circumferential overhang

66

similar, disc-like insulation element

70

Top view on different floor plans

72

Floor plan of an insulation element

74

Floor plan of wavy position offset inwards on all sides

76

Floor plan of intermediate layer with circumferential overhang

78

circumferential overhang

80

circumferential first groove

Claims (12)

Oil transformer insulation module (40, 60) with a plurality of along a line (42) arranged flush, interconnected, similar, disk-like insulation elements (10, 44, 66) each having at least a similar floor plan (72), characterized
in that an insulation element (10, 44, 66) has at least one first (12) plane and a second (14) adjacent thereto and predominantly parallel layer of a mechanically strong, flat first insulation material, that the first (12) and the second (14 Insulating material having a third intermediate corrugated layer (16) of a mechanically strong, flat, second insulating material connected and spaced apart, said third layer (16) having lateral edges and is corrugated such that all formed by the corrugated shape Hollow spaces (18, 20) over the lateral edges are flooded completely with a liquid (26). Oil transformer insulation module according to claim 1, characterized in that the third layer (16) is at least partially corrugated trapezoidal. Oil transformer insulation module according to one of claims 1 or 2, characterized in that at least one further planar layer and an associated further corrugated layer between the first (12) and second (14) layer are arranged, so that an alternating sequence of planar and corrugated Layers results. Oil transformer insulation module according to one of the preceding claims, characterized in that the first insulating material corresponds to the second insulating material. Oil transformer insulation module according to one of the preceding claims, characterized in that the height (28) of the cavities formed by the corrugated shape (18, 20) corresponds to at least twice the thickness (30) of the unwoven second insulating material. Oil transformer insulation module according to one of the preceding claims, characterized in that the lateral edges of a corrugated layer (16) on all sides offset from the edges of the adjacent planar layers (12, 14) are inwardly, so that a circumferential first groove (48, 80) is formed is. Oil transformer insulation module according to one of the preceding claims, characterized in that between at least two insulating elements (10, 44, 66) arranged one above the other, an intermediate layer (46, 62) with a similar ground plan (76) made of a solid insulating material is arranged. Oil transformer insulation module according to claim 7, characterized in that the intermediate layer (46, 62) has a floor plan (76) which is greater than the respective floor plan (72) of the adjacent insulation elements (10, 44, 66), so that through the intermediate layer ( 46, 62), a circumferential projection (64, 78) is formed. Oil transformer insulation module according to claim 7, characterized in that the intermediate layer (46, 62) has a floor plan which is smaller than the respective floor plan of the adjacent insulation modules (72), so that through the intermediate layer (46, 62) has a circumferential second groove (50 ) is formed. Oil transformer insulation module according to one of the preceding claims, characterized in that adjacent layers are connected to each other by means of a high voltage resistant adhesive. Oil transformer isolation module according to one of the preceding claims, characterized in that all the cavities (18, 20) formed by the corrugated shape are completely flooded with oil (26). Oil transformer with oil boiler and at least one oil transformer insulation module according to one of claims 1 to 11.

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