EP2924698B1 - Oil-oil feedthrough and oil transformer - Google Patents

Description

The invention relates to an oil-oil passage, comprising a rotationally symmetrical, paraboloid-like, hollow feedthrough element made of a solid insulating material, along the axial extent of which a tube-like feedthrough channel is formed radially inwardly, the wall thickness is tapered to at least one of its two ends and conical further comprising a form-fitting fitted into the duct and from this both sides outstanding electrical feedthrough conductor.

It is well known that high voltage transformers are used to transfer electrical energy between different voltage levels in power distribution networks. For example, for a rated voltage level of 110kV / 380kV they have a power of several 100MVA. Due to the high voltages each sufficiently large isolation distance between live components must be observed, which leads in particular the transformer side in the insulation medium air to a disadvantageously increased size. For this reason, transformers of such high voltage levels are usually designed as oil transformers, that is, the actual transformer is arranged in an oil-filled boiler, wherein the oil serves both as an insulating and cooling medium. Due to the high insulation resistance of oil Air thus the insulation distances and thus the size of the transformer can be reduced in an advantageous manner.

At the interfaces where current-carrying conductors are led out of the insulation medium oil into another insulation medium such as air, so-called feedthroughs are necessary in order to comply with the insulation distances required for different insulation media. However, bushings are also necessary if an electrical conductor is led from a closed space through a wall into an adjacent closed space which is filled with the same insulating medium. Such an example can also be found in an oil transformer, namely where electrical conductors are routed from the oil-filled interior of an oil boiler in which a transformer is located to an adjacent inner region of the same oil boiler, from which, for example, cable connections exit. Such bushings are called oil-oil passage. The separation of the various internal areas ultimately serves to form separate oil reservoirs. In the example mentioned, the side of the feedthrough facing the transformer is referred to as the input side and the side facing the cable space is referred to as the output side.

Such oil-oil feedthroughs are based on the prior art on a standardized so-called vacuum termination element. This is a rotationally symmetrical, paraboloid-like, hollow feedthrough element made of a solid insulating material, along the axial extent of which a tube-like feedthrough channel is formed radially inward, the wall thickness of which tapers conically towards at least one of its two ends. Finally, the shape of the feedthrough element is also comparable to that of a funnel, wherein the funnel outlet is extended rearwardly into the widened area of the funnel. The widened side of the feedthrough element is typically facing away from the transformer in the installed state and facing the cable space. The widened side of a lead-through element is therefore also referred to as the output side and the side remote from it as the input side.

A disadvantage here proves that an oil-oil implementation of the prior art based on such a standardized vacuum completion cumbersome is to be mounted, since on the output side additional barriers are necessary to control the field strength occurring during operation such that an electrical breakdown by oil is reliably avoided. Likewise, at the input side of the oil passage at higher voltages, additional insulation is required to prevent partial discharges. According to the prior art, a wound paper insulation is usually used here, which requires a high manufacturing outlay. Both the paper insulation and the barriers, which are usually made from pressboard, have a high risk of moisture absorption, which can impair their function in the oil transformer. The elimination of a paper insulation or barriers according to the invention is therefore an additional advantage, in particular in the case of on-site assembly, because there is no possibility of drying in order to counteract this effect.
The patent document JP H10 256044 A discloses a passage for an oil-cooled transformer with a paraboloid-like feedthrough element made of a solid insulating material with a centrally guided through this feedthrough conductor, at one end of a hollow cylindrical shield member is provided.
The patent document JP S56 42313 A discloses a passage for oil transformers with a conically tapered screen element.
The patent document EP 0 383 988 A1 discloses a high voltage feedthrough for oil cooled electrical appliances, in particular high voltage machine and mains transformers, in which components for electrical and mechanical connection of the end of a feedthrough conductor pin to a high voltage leading lead lie in a cup-shaped shield. An induction-poor fixed resistor forming the end of the connecting conductor lies spatially and electrically between the cup-shaped shield and a cup-shaped shielding pot similar to this one.
Based on this prior art, it is an object of the invention to provide an oil-oil passage, which on a standardized vacuum termination is based, is particularly easy to handle and which manages without additional barriers or without additional isolation effort. The object of the invention is also to provide a corresponding oil transformer.

This object is achieved by an oil-oil passage according to claim 1. The basic idea of the invention is to provide a respective dome-like screen element made of an electrically conductive material on both sides at the ends of the feedthrough channel of a known feedthrough element, which the potential distribution during operation of the oil Oil passage influenced such that no additional barriers or no additional isolation effort is required.

In order to achieve a desired screen effect, inter alia, an axial overlap of the feedthrough channel with a respective screen element is provided. Therefore, the inner diameter of such a hollow cylindrical screen element is chosen so that it is in any case greater than the outer diameter of the respective end of the axially tapering towards its two ends outwardly passage channel. The conical taper allows for increased overlap area. Furthermore, a sufficient axial length of the dome-shaped shielding elements is provided in order, inter alia, to ensure a corresponding field strength distribution by an increased distance from the wall through which the bushing is guided.

A known vacuum termination or a known rotationally symmetrical, paraboloid-like, hollow lead-through element have, for example, an outer radius of the widened (initial) side of about 30 cm, the axial length being about 26 cm. The inner diameter of the feed-through channel is constantly about 4cm, with its axial length is about 22cm. The length of a typical feedthrough conductor is approximately 43cm, resulting in a lead overhang of approximately 10cm for each side. From the bottom of the rotationally symmetric paraboloid-like hollow lead-through element, the lead-through channel extends approximately 14 cm in the axial direction to the widened (initial) side, where it has an outer diameter of approximately 4.5 cm and is approximately 4 cm from the widened end away. In the opposite direction, the passage channel extends another 8cm to the rear and has at its local end an outer diameter of about 8.2 cm.

The inner diameter of a matching screen element, which is arranged facing away from the widened (output) side, for example, is about 9 cm and is thus about 0.8 cm larger than the corresponding outer diameter of the local end of the feedthrough channel of about 8.2 cm. This allows a corresponding overlap. A corresponding outer diameter of the shielding element, which is made for example of a metal such as aluminum, is about 15cm, which gives a typical wall thickness of 30mm. By this thick wall and the thus increased outer diameter of such a screen element, the radially outwardly occurring field strength is reduced in an advantageous manner, being designed by the axial overlap of feedthrough channel and screen element of the transition area feldstärkeunkritisch. To further reduce the field strength occurring, the axial ends of the hollow cylindrical screen element are roundish. A suitable axial length of such a screen element is for example about 15 cm or more.

The inner diameter of a matching screen element, which faces the widened (output) side, for example, is about 6 cm and is thus about 1.5 cm larger than the corresponding outer diameter of the local end of the feedthrough channel of about 4.5 cm. A suitable outer diameter of the screen element is about 12 cm, which in turn results in a typical wall thickness of 30mm. A suitable axial length of such a screen element is for example about 20 cm or more. The numerical values mentioned are to be regarded as example values by which a considerable tolerance range is given.

By arranging a corresponding dome-like screen element on both sides of the feed-through channel, an oil-oil passage is formed, which can be installed in a simple manner without additional barriers or additional insulation effort and which is characterized by its robustness and compactness.

According to a particularly preferred embodiment of the oil-oil passage according to the invention, the shielding element is coated at least on its outer surface with an insulating material, in particular with an epoxy resin. As a result, an isolation of the conductor element located on the screen element is given in an advantageous manner.

According to a further embodiment of the oil-oil feedthrough according to the invention, the widened open end of the paraboloid-like feedthrough element merges into a terminating region extending radially outwards perpendicular to the axis of rotation. This allows advantageously a flanging of the end portion of the lead-through element to a perforated wall, through which the oil-oil passage is to be performed.
According to a particularly preferred variant of the oil-oil feedthrough according to the invention, the electrical feedthrough conductor fitted in the feedthrough channel has a respective shape at its two projecting ends which is suitable for the positive electrical contacting of a respective connecting conductor with a correspondingly complementary shape. Such a shape is characterized in particular by an increased contact surface between conductors to be connected. A tongue and groove shape is an example of a suitable shape. Advantageously, the conductor ends can be screwed to their respective complementary shape so as to ensure a reliable contact.

According to the invention, contacting means for its electrical contacting with the projecting feedthrough conductor or with a picked-up connecting conductor are provided in the shielding element. Thus, it is ensured that the shielding element is securely placed on the electrical potential of the performed conductor. An internal potential difference can therefore not occur and due to the increased radius of the shielding element with respect to the conductor diameter, the field strength at the outer surface of the shielding element is correspondingly reduced during operation.
According to a further variant of the invention, the contacting means of the shielding element comprise at least one ring-like and preferably resilient element made of an electrically conductive material, wherein the element is intended to surround the projecting feedthrough conductor or a received connecting conductor in a contacting manner. Due to the increased contact surface of the ring-like element to the performed conductor a secure electrical contact is ensured, wherein the ring-like element also serves for further contacting of the shield element.

According to the invention, the contacting means comprise at least one thread extending radially through the wall of the screen element and a thread arranged therein Screw for fixing the protruding lead-in conductor or a received connection conductor. If a ring-like element is provided, this can also be fixed with one or more screws and thus also a guided by this conductor.

By means of such a screw connection, the screen element can be fastened in a particularly simple manner from the outside, whereby its assembly is simplified in an advantageous manner and, moreover, a compact design is achieved.

According to a particularly preferred arrangement, at least three threads of a screen element are arranged in a star shape, preferably in a common plane perpendicular to the axial course of the conductor to be fixed. This allows a particularly secure fixation along the entire circumference of the conductor.

Following a particularly preferred embodiment variant, a shielding element comprises respective contacting means both for the protruding feedthrough conductor and for a received connecting conductor. This can be, for example, two groups of three star-shaped threads with corresponding fixing screws. Thus, the fixation and contacting of the screen element to the performed conductors is further improved.

According to a further variant of the oil-oil feedthrough according to the invention, a screen element has inner cavities, by means of which a partial reduction of its wall thickness is effected. Since the outer shape of the shielding element is unaffected by this, a reduction in material and weight thus a material and weight and thus easier handling are possible.

The object according to the invention is also achieved by an oil transformer, comprising an oil tank having a first oil-filled interior area in which a transformer is arranged, and one of them separated by a wall second oil-filled interior space, wherein the wall has at least one passage, by means of which an electric Connecting a first electrical connection conductor in the first interior with a second electrical Connecting conductor is formed in the second interior, wherein the at least one passage is an inventive oil-oil passage. The resulting corresponding benefits have already been discussed during the oil-oil implementation.

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

ein exemplarisches Durchführungselement mit Durchführungsleiter,

Fig. 2

ein exemplarisches erstes Schirmelement,

Fig. 3

exemplarisches zweites Schirmelement mit elektrischen Leitern sowie

Fig. 4

eine exemplarische Öl-Öl-Durchführung.

Show it:

Fig. 1

an exemplary feedthrough element with feedthrough conductor,

Fig. 2

an exemplary first screen element,

Fig. 3

exemplary second screen element with electrical conductors as well

Fig. 4

an exemplary oil-oil implementation.

Fig. 1 shows an exemplary feedthrough element 12 with a feedthrough conductor 18 in a sectional view 10. The made of a solid insulating material feedthrough element is rotationally symmetrical about a rotational axis 14, paraboloid-like and hollow configured. In the radial center of the lead-through element 12, a feed-through channel 16 is provided along the axial extent thereof, which has a constant inner diameter and a wall thickness which conically tapers at its two axial ends. In the passage channel a feedthrough conductor 18 is positively fitted, which protrudes from the two ends of the feed-through channel 16 and is made for example of aluminum or copper.

The widened open end of the paraboloid-like feedthrough element 12 merges into a radially outwardly adjoining end region 22 extending perpendicularly to the axis of rotation 14, which is provided for flanging the feedthrough element against a wall.

The two axial end regions of the feedthrough conductor have a stepped form 22 for positive contacting, through which an increased contact surface is provided with a conductor to be connected of complementary shape.

The Fig. 2 shows an exemplary first screen element 30 in a sectional view. This is intended to be connected to the input side of a feedthrough element. Base 48 is a hollow cylindrical body of aluminum, in this example, which extends along and about a rotation axis 32. The axial ends 34 of the base member 48 are rounded to avoid sharp edges with a correspondingly increased in operation field strength. Along the axial extent of the base element 48, three inner cavities 42 are provided, which leave the outer shape of the base element 48 unaffected and lead to a weight saving. In the region of the inner cavities 42, the wall thickness is reduced, as indicated by the dashed lines with the reference numeral 46, whereas in the other areas a high wall thickness of, for example, 3 cm is provided, as indicated by the dashed area by the reference numeral 44.

In areas with high wall thickness 44 radially arranged threads 36 are provided, in which screws 38 are arranged. With the screws, a pressure on ring-like elements 40 is made possible, within which thereby a not shown conductor can be fixed.

The Fig. 3 shows an exemplary second shielding element 52 with electrical conductors 56, 58 in a sectional view 50. The shielding element 52 is intended to be connected to the output side of a feedthrough element. Basic element is a hollow cylindrical body made of aluminum in this example. By means of ring-like elements 54, a first 56 and a second 58 conductors are fastened inside the screen element 52 using screws. The conductors 56, 58 have a respective complementary stepped shape of one of their respective ends, so that thereby a positive contact 60 is given.

The Fig. 4 shows an exemplary oil-oil passage 70 in a three-dimensional sectional view. In the feedthrough channel of a feedthrough element 72 is a feedthrough conductor 76 fitted. This is connected at its output end with a first connecting conductor 74 and at its input end with a second connecting conductor 78. To the output-side connection point, a first screen element 80 is arranged overlapping with the corresponding one axial end of the feedthrough channel and a second screen element 82 is arranged around the input-side connection point overlapping with the corresponding other axial end of the feedthrough channel. The simple and robust construction of the thus assembled oil-oil passage is easy to recognize.

LIST OF REFERENCE NUMBERS

10

exemplary feedthrough element with feedthrough conductor

12

Through element

14

axis of rotation

16

Through channel

18

Through conductors

20

Form for positive contact

22

termination region

30

exemplary first screen element

32

axis of rotation

34

round design of the axial end of the first screen element

36

thread

38

screw

40

ring-like element

42

inner cavity

44

Area with high wall thickness

46

Area with reduced wall thickness

48

body

50

exemplary second screen element with electrical conductors

52

second screen element

54

ring-like element

56

first leader

58

second conductor

60

positive electrical contact

70

exemplary oil-oil discharge

72

exemplary implementation element

74

first connection conductor

76

Through conductors

78

second connection conductor

80

first screen element

82

second screen element

Claims (9)

1. Oil-oil bushing (70), comprising

   • a rotationally symmetrical (14), paraboloid-like, hollow bushing element (12, 72) of a solid insulating material, along the axial extent of which there is formed radially toward the inside a tubular bushing channel (16), the wall thickness of which is tapered conically toward at least one of its two ends,

   • an electrical bushing conductor (18, 76) fitted into the bushing channel (16) with a form fit and protruding from it on both sides,

   • wherein at at least one of the two axial ends of the bushing channel (16) there is arranged a respective hollow-cylindrical shielding element (30, 52, 80, 82) of a conductive material, which is thick-walled (44) at least in certain regions, which element encloses on its one side the respective end of the bushing channel (16) and the bushing conductor (18, 76) protruding from it and on its other side, respectively, is intended for receiving and electrically contacting a respective connecting conductor (74, 78),

   • wherein the axial ends of the shielding element (30, 52, 80, 82) are of a round design,

   • wherein contacting means are provided in the shielding element (30, 52, 80, 82) for its electrical contacting with the protruding bushing conductor (18, 76) or with a received connecting conductor (74, 78),

   characterized in that
   the contacting means comprise at least one thread (36) running radially through the wall of the shielding element (30, 52, 80, 82) and also a screw (38) arranged therein for fixing the protruding bushing conductor (18, 76) or a received connecting conductor (74, 78).
2. Oil-oil bushing according to Claim 1, characterized in that the shielding element (30, 52, 80, 82) is coated at least on its outer surface with an insulating material, in particular with an epoxy resin.
3. Oil-oil bushing according to Claim 1 or 2, characterized in that the widened open end of the paraboloid-like bushing element (12, 72) goes over into a radially outwardly adjoining terminating region (22) running perpendicularly in relation to the axis of rotation (14) .
4. Oil-oil bushing according to one of the preceding claims, characterized in that the electrical bushing conductor (18, 76) fitted into the bushing channel (16) has at both of its protruding ends a respective form (20) that is suitable for the form-fitting electrical contacting (60) of a respective connecting conductor (74, 78) with a correspondingly complementary form.
5. Oil-oil bushing according to one of the preceding claims, characterized in that the contacting means of the shielding element (30, 52, 80, 82) comprise at least one annular element (40, 54) of an electrically conductive material, which is intended for enclosing the protruding bushing conductor (18, 76) or a received connecting conductor (74, 78) in a contacting manner.
6. Oil-oil bushing according to one of the preceding claims, characterized in that at least three threads (36) of a shielding element (30, 52, 80, 82) are arranged in the form of a star.
7. Oil-oil bushing according to one of the preceding claims, characterized in that a shielding element (30, 52, 80, 82) both for the protruding bushing conductor (18, 76) and for a received connecting conductor (74, 78) comprises respective contacting means.
8. Oil-oil bushing according to one of the preceding claims, characterized in that a shielding element (30, 52, 80, 82) has internal cavities (42), by which a reduction (46) of its wall thickness in certain portions is brought about.
9. Oil transformer, comprising an oil tank with a first oil-filled internal space area, in which a transformer is arranged, and with a second oil-filled internal space area that is separated from the first area by a wall, the wall having at least one bushing, by means of which an electrical connection of a first electrical connecting conductor (74, 78) in the first internal space to a second electrical connecting conductor (78, 74) in the second internal space is formed,
   characterized,
   in that the at least one bushing is an oil-oil bushing (70) (30, 52, 80, 82) according to one of Claims 1 to 8.

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