EP2256753A1 - Electricity conductor for a high voltage feed - Google Patents

Abstract

The electrical conductor has two electrical connections (10, 20) are being connected without joint to a lower and an upper end of a conductor element (30) respectively. The lower electrical connection has an oval profile at right angles to an axis, with two contact surfaces. A hollow electrical conductor section (40) is arranged between the lower electrical connection and lower end of the conductor to connect lower electrical connection to conductor. The hollow section forms a smooth transition from the two contact surface to the envelope surface of the conductor. Independent claims are included for the following: (1) high current bushing having an electrical conductor; and (2) method for producing high current bushing having an electrical conductor.

Description

TECHNICAL AREA

The present invention relates to a current conductor according to the introductory part of claim 1. The invention also relates to a high current feedthrough with such a current conductor and a method for producing this high current feedthrough.

High current feedthroughs are used in power station transformers and are located in the current path between the generator and the primary windings of the transformer in a generally encapsulated generator lead, which are loaded at comparatively low rated voltages of up to 52 kV with rated currents up to 40 kA. Because of the low dielectric and the high thermal load, high current feedthroughs have a relatively short current conductor with a large diameter. Therefore, heat generated in the conductor of the bushing due to current loss is rapidly conducted to its two ends, each formed as a power terminal. A first of the two power connections is located in the oil of the transformer and is connected to its primary winding. He has - as prescribed by the transformer manufacturers - two mutually parallel contact surfaces. The second power connection is generally located in the air-filled enclosure of the generator lead and is connected to a live conductor of the drain.

The rated current carrying capacity of the high-current feedthroughs is determined essentially by the comparatively high temperatures occurring at the power connections and the permissible temperature of the insulating material used in the feedthrough.

STATE OF THE ART

A current conductor of the type mentioned above is used in a transformer feedthrough type GOH and is described in the published by ABB Power Technologies AB Components, 77180 Ludvika, Sweden, technical instructions 1ZSE 2750-107 de, Rev 1, 2000-04-15. This conductor contains a rigid aluminum bolt, in which in the oil of the transformer guided first end of a power connection with two mutually parallel aligned contact surfaces and cooling elements are milled. The air-guided second end of the bolt is equipped with four drilled flat terminals, which are welded to the bolt.

A current conductor for a high current feedthrough of the type RTXF which can be used in transformers is described in a company publication D 4317 published by Micafil AG, Zurich / Switzerland. This conductor is tubular and includes at both ends of the tube arranged, plate-shaped power connections, which are held on two the two ends of the tube final end plates.

The current conductors of the prior art include a plurality of electrically conductive parts joined together by welding or soldering. Therefore, in a current path extending between the two current connections, joints are present, which increase the electrical resistance in the current path and thus contribute to an increase in the electrical losses.

PRESENTATION OF THE INVENTION

The invention, as indicated in the claims, the object of the invention is to provide a conductor of the type mentioned and a high-current implementation with such a conductor, which are characterized by a small size by low electrical losses in a compact design.

In the current conductor according to the invention, a first power connection is hollow and has transverse to the axis oval profile with two sides forming the two longitudinal sides, is disposed between the first power terminal and a first end of a conductor piece, a hollow conductor section, which is the first power connection to the conductor piece connects and forms a smooth transition from two contact surfaces of the first power connection to a cylindrical outer surface of the conductor piece, and a second power connection without a joint is connected to a second end of the conductor piece.

The current conductor according to the invention comprises only a single current-conducting part and can therefore be manufactured directly from a suitable metal or a suitable alloy, for example based on aluminum, without complicated connecting techniques. A current path extending between the two current connections during operation of the current conductor has lower electrical losses because of missing joints compared to a current conductor according to the prior art. Since both power connections are each seamlessly integrated into the current path, a uniform distribution of the current in the conductor is achieved even if the power supply lines are asymmetrically or incompletely connected to connecting conductors. In addition, due to the oval profile of the first power supply and the smooth transition from its two parallel aligned contact surfaces on the cylindrical surface of the hollow conductor piece on the one hand, the electrical losses in the current path is additionally reduced and so on the other an excessive local heating of the conductor avoided. The oval profile of the first power connector contains two elbows that connect the two contact surfaces. These elbows ensure that the first electrical connection has a high mechanical strength and is also characterized by a relatively large surface, which quickly releases heat due to the electrical losses in the conductor heat to the outside.

In order to increase the rated current flowing during operation in the current conductor, it is advantageous to arrange a first cooling system inside the hollow conductor section. A manufacturing technology advantageous integration of this cooling system in the conductor is achieved with axially aligned cooling elements, the a radially extending wall termination of the hollow conductor section are arranged. At the same time, preferably designed as needles or ribs cooling elements are protected by the surrounding wall of the hollow conductor section from mechanical damage.

The replacement of heated coolant, such as in particular transformer oil, which is located in the hollow conductor section and heat extracts the first cooling system and the power connector is improved when in the hollow conductor section radially outwardly bounding wall openings are formed.

If a radially outwardly extending support ring with axially aligned pins is formed in the hollow conductor section, then the production of a high current feedthrough using the current conductor is considerably simplified.

A higher rated current carrying capacity of the conductor according to the invention is achieved when the conductor piece is formed as a hollow cylinder, when the second power connector is formed in a tubular extension of the hollow cylinder, and when the hollow cylinder and the tube extension are separated by a radially guided closure plate. Since the rated current is guided in a hollow, largely rectilinear current path, which has neither joints nor edges, the electrical losses are reduced during operation of the conductor particularly strong. If a second cooling system, which has axially aligned cooling elements arranged on the partition wall, is arranged in the interior of the tubular extension, the nominal flow can be increased still further because of the increased cooling capacity.

The current conductor according to the invention and at least one of the aforementioned, optionally in the conductor integrated devices, such as the first or second cooling system or the externally accessible support ring, may be designed as a cast body. There are then avoided in a particularly simple manner, the undesirable joints and achieved by integrating one or more of the additional devices functions that favor the cooling of the conductor and the production of the current conductor containing high current feedthrough.

A high-current bushing with a current conductor according to the invention has a first support ring serving to support prestressed compression springs and held on the current conductor. The conductor is coaxially surrounded by a hollow cylindrical field control body supported on the prestressed compression springs, a mounting flange supported on the field control body, an insulator supported on the mounting flange, and a second support ring supporting the insulator and frictionally connected to the conductor. The first support ring is in this case formed in the hollow conductor section and has axially aligned pin for guiding the compression springs.

Such a high current feedthrough is characterized by low electrical losses and a correspondingly high rated current carrying capacity. It can also be made in a process suitable for mass production. In this manufacturing process, the compression springs are plugged onto the axially aligned pin and a support ring is pushed from above onto the conductor and stored on upwardly free ends of the compression springs. Then are pushed onto the conductor sealing rings, the field control body, the mounting flange, the insulator and the second support ring. A stack thus formed is biased by a force acting on the second support ring and the second support ring is finally connected non-positively while maintaining the biasing force with the conductor.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1

eine Aufsicht in radialer Richtung auf eine längs einer Achse A ausgerichtete Hochstromdurchführung mit einem Stromleiter nach der Erfindung, bei der die Durchführung in der rechten Hälfte teilweise längs der Achse geschnitten dargestellt ist,

Fig.2

eine von unten geführte Ansicht des Stromleiters der Durchführung gemäss Fig.1, und

Fig.3

eine Draufsicht auf den Stromleiter der Durchführung gemäss Fig.1.

With reference to drawings, embodiments of the invention will be explained in more detail below. Hereby shows:

Fig.1

a view in the radial direction on a along a axis A aligned high-current feedthrough with a conductor according to the invention, in which the implementation in the right half is shown partially cut along the axis,

Fig.2

a bottom view of the conductor of the implementation according to Fig.1 , and

Figure 3

a plan view of the conductor of the implementation according to Fig.1 ,

WAYS FOR CARRYING OUT THE INVENTION

In the Fig. 1 illustrated high-current feedthrough is formed along the axis A largely cylindrically symmetrical and has the marked with the reference S conductor, which is surrounded in a coaxial arrangement of a hollow cylindrical field control body F and guided around the field control body hollow cylindrical insulator I.

The field control body F is designed as a support insulator known from the prior art and has a solidified with a cured thermosetting polymer, the electric field of the implementation capacitively controlling winding body containing an insulating film and embedded in the foil, each other electrically insulated sheet metal coatings. The field control body F is seated with its lower end on a support ring SR, which in turn is held resiliently on a held at the lower part of the conductor ring of biased compression springs D. In the lateral surface of the field control body a not apparent from the figure shoulder is formed, on which a mounting flange M is seated with a lower end face. On the upper end surface of the mounting flange M sits on a lower end face of the provided with a shielding insulator I. On the upper end face of the insulator I is seated on a support ring T, which is fixed in the upper part of the conductor S with the aid of a not shown - executed as a snap ring - fastener. A not apparent from the figure, from the conductor S inwards, the support ring T up, the support ring SR and the mounting flange M down and the field control body F and the insulator I to the outside limited, annular cavity is closed with not designated seals and an insulating potting filled.

The implementation can be used in any position in an opening in a transformer housing and with the mounting flange M air and oil-tight attached to the housing. The lower end of the conductor S is designed as a power connection 10 and is electrically connected to the assembly of the implementation by means of connecting screws, which are guided in holes 12 of the power connector 10, with a primary winding of the transformer. The power connector 10 is located during operation of the bushing inside the transformer filled with insulating oil. The upper end of the current conductor S is designed as a power connection 20 and is also electrically connected during installation of the implementation by means of screws which are guided in bores 22 with a generally arranged in a grounded, air-filled metal encapsulation phase conductor of a generator lead. The bushing is designed so that it can be loaded during operation with rated currents of up to 40 kA and rated voltages of up to 52 kV.

The current conductor S is formed by an electrically conductive cast body, which typically consists of a castable aluminum alloy. This cast body has in addition to the two power terminals 10 and 20 as a hollow cylinder 30 formed, along the axis A extending conductor piece with a cylindrical surface. The power connector 10 has two mutually parallel contact surfaces 11, 11 'on (off Fig.2 visible), of which a part of the contact surface 11 in Fig.1 is shown. Both power connections 10, 20 are hollow. Out Fig.2 It can be seen that the power connector 10 has perpendicular to the axis A oval profile with two the two contact surfaces 11, 11 'forming longitudinal sides. Between the power connector 10 and the lower end of the conductor piece 30, a hollow conductor section 40 is arranged. This section connects the power connector 10 to the conductor piece 30 and forms a smooth transition from the two contact surfaces 11, 11 'on the cylindrical surface of the conductor piece 30. The hollow-shaped power terminals 10 and 20 and the hollow power section 40 ensure that the current conductor S is optimized not only in the form of a hollow cylinder conductor piece 30, but also in its end with respect to the suppression of eddy currents and the skin effect.

Because of its design as a cast body, the current conductor 1 in a current path between the two current terminals 10, 20 has no joint. Otherwise, a joint is created when the conductor is manufactured from two or more components. Here, the two components are brought together to form a joint at joining surfaces and then by joining the joint, such as metal when welding or soldering, materially connected together. When operating the implementation occurring electrical losses and associated heating of the implementation are therefore smaller than in a comparably sized and comparatively loaded implementation of the prior art, which has a conductor with at least one Fugestelle. Because of the oval profile of the power connector 10 and the flowing, free of edges and abrupt changes in direction, which are typically 90 ° in the prior art, held transition from the two parallel contact surfaces 11, 11 'on the cylindrical surface of the hollow conductor piece 30 the electrical losses in the current path additionally reduced and local heating due to increased power dissipation largely avoided at otherwise existing points of discontinuity.

The oval profile of the power connector 10 has two Fig.2 apparent bow pieces 13, 13 ', which connect the two contact surfaces 11, 11' together. These curved pieces cause a high mechanical strength of the power connector 10. They also increase the surface and ensure that due to electrical losses in the conductor S heat is released quickly to the surrounding transformer oil.

The hollow conductor portion 40 disposed in the transformer oil receives a cooling system 50. This cooling system is integrated into a radially extending wall termination 41 of the hollow conductor section 40 and has cooling elements 51 formed as needles or ribs. The hollow conductor section 40 is bounded radially outwardly by a wall in which openings 42 are formed. The openings 42 ensure that transformer oil, which has been heated by absorbing heat loss at the cooling system 50, flows radially outward from the interior of the section 40 and the power connection 10 and can be rapidly replaced by axially flowing cool oil.

In the hollow conductor section 40 an externally accessible support ring 60 is formed with axially directed pin 61. On this pin, the bias voltage generating compression springs D are slidably mounted in the axial direction.

The from the FIGS. 1 and 3 apparent power connection 20 is formed in a tubular extension 31 of the hollow cylinder 30 and has a plurality, here eight, arranged on the manner of a regular polyhedron contact surfaces 21. Hollow cylinder 30 and tube extension 31 respectively. Power connection 20 are separated by a radially guided closure plate 32, into which a in the interior of the air-filled tube extension 31 optionally arranged cooling system 70 may be integrated. The cooling system 70 has axially aligned and formed as needles or ribs cooling elements 71 and increases as the cooling system 50, the rated current carrying capacity by additional cooling of the conductor S.

To produce the current conductor S, a casting core held on a rod and determining the inner contours of the tube extension 31, the hollow cylinder 30 and the wall termination 41 is arranged in a two-part casting mold. The mold determines the outer contours of the tube extension 31, respectively. the power connector 20 and the hollow cylinder 30 and the inner and outer contours of the hollow power connector 10 and the hollow conductor section 40, including the bearing ring 61 containing the support ring 60 and the cooling system 50. The closed mold is filled with a melt of an aluminum alloy and after cooling and Demoulding the executed as a cast body conductor S obtained. Because of the Giesskern holding rod, the cast body has a centrally disposed in the wall end 41 opening, which is bounded by an axially downwardly extending pipe socket 43. In order to prevent the penetration of the oil into the interior of the hollow cylinder 30 of the pipe socket is closed with a perpendicular to the axis A guided plate 44. In a corresponding manner, the penetration of air into the cavity of the current conductor S bounded by the hollow cylinder 30 is prevented by the wall 32 guided perpendicularly to the axis A.

In order to meet certain specifications made of the conductor, the casting is optionally machined by machining. Typically, the contact surfaces 11, 11 ', 21 are formed by milling and the openings provided for guiding the connecting screws and the openings 42 are formed by drilling.

In the manufacture of the high-voltage bushing, the compression springs D are first attached to the axially aligned pin 61 and the support ring SR is pushed from above onto the current conductor S and stored on upwardly free ends of the compression springs. Subsequently, on the current conductor S, sealing rings, the field control body F, the mounting flange M, the insulator I and the support ring T are pushed. A thus formed stack is compressed with a force acting on the support ring T force to form biasing force and the support ring T while maintaining the biasing force by means of the fastener frictionally fixed to the conductor S.

LIST OF REFERENCE NUMBERS

10

power connection

11, 11 '

contact surfaces

12

openings

13, 13 '

elbows

20

power connection

21

contact surfaces

22

openings

30

Conductor piece, hollow cylinder

31

Tubular extension

32

closing plate

40

Conductor section

41

wall end

42

openings

43

pipe socket

44

closing plate

50

cooling system

51

cooling elements

60

support ring

61

Pins, guide elements

70

cooling system

71

cooling elements

A

axis

D

compression springs

F

Field control body

I

insulator

M

mounting flange

S

conductor

SR

support ring

T

support ring

Claims (10)

Conductor (S) for a high-current leadthrough comprising a conductor piece (30) extending along an axis (A) with a cylindrical outer surface and two electrical connections (10, 20), of which a first (10) without a joint with a first of both ends of the conductor piece (10). 30) and has two mutually parallel contact surfaces (11, 11 '), characterized in that the second (20) of the two electrical connections (10, 20) without a joint to the second end of the conductor piece (30) is connected the first power connection (10) is hollow and perpendicular to the axis (A) oval profile with two the two contact surfaces (11, 11 ') forming longitudinal sides, and that between the first power connector (10) and the first end of the conductor piece (30 ) a hollow conductor section (40) is arranged, which connects the first electrical connection (10) with the conductor piece (30) and a smooth transition from the two contact surfaces (11, 1 1 ') of the first electrical connection (10) on the lateral surface of the conductor piece (30). Electric conductor according to Claim 1, characterized in that a first cooling system (50) is arranged in the interior of the hollow conductor section (40). Electric conductor according to claim 2, characterized in that the first cooling system (50) comprises axially aligned cooling elements (51) which are arranged on a radially extending wall termination (41) of the hollow conductor section (40). Conductor according to one of claims 1 to 3, characterized in that in the hollow conductor section (40) radially outwardly bounding wall openings (42) are formed. Electric conductor according to one of claims 1 to 4, characterized in that in the hollow conductor section (40) a radially outwardly extending support ring (60) is formed with axially directed pin (61). Conductor according to one of claims 1 to 5, characterized in that the conductor piece (30) is designed as a hollow cylinder, that the second Power terminal (20) is formed in a tubular extension (31) of the hollow cylinder, and that the hollow cylinder (30) and the tube extension (31) by a radially guided closure plate (32) are separated from each other. Electric conductor according to Claim 6, characterized in that a second cooling system (70) fastened to the closure plate (32) is arranged in the interior of the tube extension (42) and has axially aligned cooling elements (71). Current conductor according to one of claims 1 to 7, characterized in that the current conductor (S) is designed as a cast body. High-current bushing with a current conductor according to one of claims 1 to 4 or 6 to 8 with a support of prestressed compression springs (D) serving, on the conductor (S) held first support ring (60), wherein the current conductor (S) in a coaxial arrangement of a supported on the biased compression springs (D), hollow cylindrical field control body (F), supported on the field control body mounting flange (M) supported on the mounting flange insulator (I) and an insulator supporting and frictionally connected to the conductor (S) support ring (T) is surrounded, and wherein the first support ring (60) in the hollow conductor portion (40) is formed and axially aligned pins (61) for guiding the compression springs (D). A method for producing the high-current leadthrough according to claim 9, characterized in that the compression springs (D) are mounted on the axially aligned pins (61), that a support ring (SR) pushed from the top of the conductor (S) and upwardly free ends the compression springs (D) is stored, that on the current conductor (S) sealing rings, the field control body (F), the mounting flange (M), the insulator (I) and the second support ring (T) are postponed that so formed a stack with a force acting on the second support ring (T) is biased, and in that the second support ring (T) is non-positively connected to the conductor (S) while maintaining the prestressing force.

Images