EP2245639B1 - High-voltage insulator - Google Patents

Abstract

A high-voltage insulator includes a metal armature, an insulating tube joined to the metal armature, which is adhesively bonded to the metal armature at an end formed as a supporting ring, and an axially symmetrical adhesive-bonding joint disposed around the axis of the insulating tube. An annular grove, which is formed in the metal armature, is disposed around the axis of the insulating tube and receives an end portion of the supporting ring. Sealing surfaces are respectively formed in the groove and in the supporting ring. The sealing surfaces are arranged and formed in such a way that, when the insulating tube and the metal armature are joined, they slide on one another, thereby forming a seal, and the supporting ring acting as a displacement body presses adhesive that has been introduced into the groove before the joining into the adhesive-bonding joint.

Description

TECHNICAL AREA

The present invention relates to a high voltage insulator according to the preamble of claim 1, a method of manufacturing a high voltage insulator and a cooling element with this high voltage insulator.

The above-mentioned high-voltage insulator includes a metal fitting, an insulating tube, which is glued to an end formed as a support ring with the metal fitting, and guided around the axis of the insulating, axially symmetric adhesive joint. The adhesive joint is bounded on the inside by an adhesive surface arranged on the support ring and to the outside by an adhesive surface arranged on the metal fitting and filled with a hardened adhesive layer in a vacuum-tight manner. In general, in this high-voltage insulator the end facing away from the support ring of the insulating tube is also formed as a support ring and connected via an adhesive joint with another metal fitting.

Such an insulator can be used as an insulating section in a passive cooling of a high-current high-voltage device, with high voltage basically an operating voltage greater than 1 kV to understand. However, the preferred voltage range is below 100 kV and mainly relates to high-current devices and systems with nominal voltages of typically 10 to 50 kV.

The current carrying capacity of such apparatus and equipment is thermally limited. For nominal currents in the range of typically 10 to 50 kA, as they are performed as in designed as a generator switch high current devices, therefore, particularly active cooling elements (eg air-air heat exchanger with Fans) or passive cooling elements used with particularly good efficiency, in particular heat pipes (heat pipes), which also contain an evaporator and a heat exchanger and a working fluid in addition to the high-voltage insulator defined above. Heat generated in the high-current device due to current losses is used to evaporate the working fluid. The vaporized working fluid is transported to an externally arranged heat exchanger and returns there by condensation, the heat loss formed in the high-current device again.

As a generator switch running high-current devices are generally carried out single-phase encapsulated and have a disposed in the enclosure and located at high voltage potential inner conductor. Heat generated by current losses on the inner conductor is dissipated through the enclosure to the ambient air. This means that there must be an electrically insulating path between a high-voltage potential evaporator and a heat pipe condenser held at ground potential, which must be designed according to the required high voltage (e.g., 150 kV BIL). Evaporator and heat exchanger (condenser) are vacuum-sealed at the two ends of the high-voltage insulator.

Since in such a high-performance, passive cooling element moving parts, such as fans or blowers omitted, can with this cooling element, the heat loss cheap and efficiently removed from the enclosure. Furthermore, such a cooling element is maintenance-free. The high-voltage insulator fulfills several functions, especially those of the guide of the working fluid and the separation of the potentials of evaporator and condenser. The reliability of such a powerful passive cooling element and equipped with such a cooling element high-voltage system is only guaranteed if the insulator performs the above functions over many years. Such an insulator should therefore be maintenance-free over a long period, typically 20 years. Such a high long-term stability requires an extremely low leakage rate. A loss of work equipment and the ingress of air and moisture are thus avoided.

STATE OF THE ART

A high voltage insulator of the aforementioned type is described in DE 694 762 C , This high voltage insulator has a metal cap d and a rod insulator a fitted with the metal cap. In the metal cap a groove c is formed, in which an annular trained gripping head b of the rod insulator a penetrates to form the joint. A cavity present between the cap and the gripping head is filled by a layer g of a solidifying binder. For the introduction of the binder and to ensure a uniform hardening of the same, the cap d is provided with channels h. To prevent ingress of water, these channels are sealed after introduction and curing of the binder with an elastic mass.

The production of such a high-voltage insulator is relatively expensive, since the binder must be introduced from the outside through the metal cap into the cavity defined by two parts to be joined. In addition, when introducing the binder through the channels air bubbles or water can enter the cavity and thereby reduce the dielectric strength of the insulator.

DE 533 573 C shows a high voltage insulator used as a supporter of a high voltage line with a hollow body a closed on one side, which is cemented into a grounded socket b and carries a cap carrying the high voltage line.

In CH 89 623 A a high-voltage insulator is described in which the outer surface of an insulator o within a hollow metal cap m has a bead-like thickening p over which the cap protrudes. A high electric field strength and thus glow or sliding spark at the triple point of metal cap, insulator and air are thus avoided.

Another high voltage insulator is in WO 2006/053552 A1 described. The high-voltage insulator described is part of a heat pipe designed as a hollow cooling element, which serves to dissipate heat from a generator lead. He has a coaxial arrangement a mechanical supporting insulating tube made of a reinforced with fibers and / or filler polymer and coaxially held diffusion barriers and two hollow metal fittings, which are bonded vacuum-tight with the two, each designed as a support ring ends of the insulating tube. Between an adhesive surface of each of the two support rings and an adhesive surface of each of the two metal fittings extending from the front side of each support ring on its lateral surface adhesive joint is provided, which is filled vacuum-tight with a set adhesive layer.

On one of the two metal fittings a held at the potential of a high-voltage conductor evaporator is attached to the other fitting held at the potential of a grounded enclosure capacitor. The high-voltage insulator forms an insulating section of a cooling element which transmits heat formed by current losses in the high-voltage conductor to the encapsulation. Here, a working medium contained in the interior of the cooling element, such as in particular acetone or a hydro-fluoro ether, the heat transfer and circulates as vapor from the evaporator through the insulating tube to the condenser, in which the vapor condenses while releasing the heat as a liquid. The liquid is returned to the evaporator through the high voltage insulator. The high-voltage insulator therefore serves not only as an insulating section, but also as a conduit for the working fluid. Since this line receives a chemical medium, a continuous temperature of typically 80 ° C is exposed and must be liquid, gas and vacuum tight over many, typically 20 years, are to the adhesive joints between each formed as a support ring both ends of the insulating tube and high demands placed on metal fittings.

PRESENTATION OF THE INVENTION

The invention, as indicated in the claims, the object is to provide a high-voltage insulator of the type mentioned, which has a low leakage rate and also after many years of operation under strong mechanical, electrical, thermal and chemical stress characterized by a high level of operational reliability, and to provide a method for producing this high-voltage insulator and a cooling element containing this insulator.

In the high-voltage insulator according to the invention, an inner flank of a groove formed in a metal fitting carries a first sealing surface which centers a supporting ring of an insulating tube, and a second sealing surface is formed in the supporting ring. Both sealing surfaces are arranged and designed such that during grouting of insulating tube and metal fitting, the two sealing surfaces slide on each other to form a seal and acting as a displacement carrier ring before grouting in the groove introduced adhesive in a grouting between an outer surface of the support ring and an outer Edge of the groove formed Klebfuge presses.

Due to the appropriate arrangement and design of metal fitting and insulating the production of the high-voltage insulator is greatly simplified. The pre-Grouting introduced into the groove adhesive is pressed only by the force applied during the joining force in the bond line. Therefore, channels extending through the metal fitting and providing adhesive feed and devices for generating compressed adhesive entering the channels may be eliminated. With simple means and in a relatively short time so a particularly homogeneous and held free of unwanted trapped air, hardened adhesive layer between the support ring and the metal fitting is achieved. Adhesive surfaces of the two glued together parts are covered to 100% with set adhesive and the entire bond line is completely filled with set adhesive.

Because of the sliding on each other during grouting and thereby forming a seal for the adhesive sealing surfaces of the adhesive is exposed during grouting a static pressure sufficient to fill a fully extended in the axial direction far beyond the two sealing surfaces adhesive joint with adhesive. In the set adhesive unavoidable diffusion paths for air and water are kept so large. Therefore, the high-voltage insulator according to the invention and a cooling element containing this high-voltage insulator are distinguished by a very small one Leakage rate and by excellent dielectric behavior, in particular a high tracking resistance, from. High voltage insulator and cooling element according to the invention accordingly have a high long-term stability. In addition, metal fittings can now be used in the manufacture of the insulator, which enclose after completion of the insulator only accessible from the interior of the insulating tube from cavity.

If the end portion of the support ring supported at the bottom of the groove, then increase the good mechanical properties of the high-voltage insulator in addition and it is then pressed during manufacture, virtually all of the adhesive from the groove bottom in the glued joint, whereby a good adhesive bond is achieved with little glue.

If the adhesive joint extends into the base of the groove and if it is connected at the end remote from the base of the groove to at least one ventilation opening guided outwards through the metal fitting, then excess adhesive and air can escape from the entire adhesive joint when the insulating pipe and metal fitting are glued together. It is so effectively prevented that in the dielectrically particularly critical boundary region between the metal fitting, insulating tube and air (triple point) adhesive passes, whereby a mechanically, vacuum technically and dielectrically particularly high-quality adhesive bond between insulating and metal fitting is ensured.

If the outer groove flank extends further in the axial direction than the inner groove flank and if a guide surface centering the support ring is formed on the end of the outer groove flank facing away from the groove base, then this guide surface and the centering sealing surface formed in the inner groove flank can have a low production engineering advantage Have expansion in the axial direction. A secure centering of the insulating tube via two in the axial direction with a relatively large distance held in the metal fitting guide surfaces is then yes guaranteed.

Unavoidable mechanical stresses in the set adhesive layer are considerably reduced if the cross-section of the joint decreases from the bottom of the groove to the vent opening. Such a cross section is in manufacturing technology advantageously achieved by conical formation of the adhesive tube arranged on the insulating surface and by cylindrical formation of the arranged on the metal fitting adhesive surface.

If at least one of the abovementioned two adhesive surfaces has at least one rib extending predominantly in the circumferential direction, then the diffusion path for moisture and air penetrating from the outside into the adhesive joint is lengthened, thus largely avoiding undesired penetration of moisture and air into the interior of the high-voltage insulator. At the same time the juxtaposition of several small air bubbles in the axial direction is counteracted in the adhesive and so a vacuum-tight seal is achieved.

In a method for producing this or another high-voltage insulator with a metal fitting, an insulating tube and guided around the axis of the insulating, annularly shaped adhesive joint, which is bounded inwardly by a support ring of the insulating tube and to the outside of the metal fitting, suitable method is before Grouting the groove at least partially filled with uniformly distributed in the circumferential direction in the groove, liquid adhesive is grouted during grouting of the liquid adhesive acting as a displacement body support ring from the groove in the bond line, and are excess adhesive and air during the pressing process through at least one The metal fitting guided vent opening is removed from the glued joint to the outside.

The liquid adhesive is therefore introduced free of air bubbles and well distributed in the joint, whereby a vacuum-tight adhesive bond is achieved in a safe and easily reproducible manner. The method therefore enables vacuum-tight high-voltage insulators with a low leakage rate and a long service life to be produced virtually without rejects.

Further features and further advantageous effects of the invention will become apparent from the embodiment described below.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1

eine Aufsicht auf einen längs einer Rohrachse geführten Schnitt durch einen als Kühlelement ausgebildeten Hochspannungsisolator nach der Erfindung,

Fig. 2

in vergrösserter Darstellung eine Metallarmatur des Hochspannungsisolators gemäss Fig.1, in die beim Fertigen des Isolators gerade flüssiger Klebstoff eingebracht wird,

Fig. 3

die Metallarmatur gemäss Fig.2, welche nach dem Einbringen des Klebstoffs gerade mit einem Isolierrohr des zu fertigenden Isolators verfugt wird, und

Fig. 4

die Metallarmatur gemäss Fig.3, welche nach dem Verfugen mit einer ausgehärteten Klebstoffschicht an einem als Tragring ausgebildeten Ende des Isolierrohrs festgesetzt ist.

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

Fig. 1

a plan view of a guided along a tube axis section through a designed as a cooling element high-voltage insulator according to the invention,

Fig. 2

in an enlarged view of a metal fitting of the high voltage insulator according to Fig.1 into which liquid adhesive is being applied when manufacturing the insulator,

Fig. 3

the metal fitting according to Fig.2 , which is grouted after the introduction of the adhesive just with an insulating tube of the insulator to be manufactured, and

Fig. 4

the metal fitting according to Figure 3 which is set after grouting with a cured adhesive layer on a trained as a support ring end of the insulating tube.

WAY FOR CARRYING OUT THE INVENTION

In all figures, like reference numerals refer to like-acting parts. An in Fig.1 The tubular high-voltage insulator shown comprises an insulating tube 1 extending along an axis A and provided with a creepage-extending shield on its outside. The insulating tube 1 is made of a polymeric composite, for example based on a duromer such as an epoxide, and a filler such as silica flour or glass fibers, but may also be made of a ceramic such as porcelain. The two ends of the insulating tube 1 are each formed as a support ring 10 and 10 'and are each vacuum-tight in a coaxial arrangement with a metal fitting 2 and 2' glued. Obviously, the upper armature 2 is annular and provided with an external thread 20 and a guided around the insulating field electrode 21, which during operation of the insulator controls the electrical field caused by the applied high voltage in the triple point formed by metal fitting, insulating tube and surrounding air. On the external thread 20, a metal vessel can be screwed vacuum-tight. The interior of this vessel is then connected in a vacuum-tight manner to the interior of the insulating tube 1. The lower armature 2 'includes a guided around the insulating tube 1 field electrode 21' and is already formed as a vessel. Therefore, the fitting 2 'has a communicating with the interior of the tube 1 cavity.

Such a sealed insulator can be filled with a working medium, in particular acetone or hydro-fluoro ether. When installed in a high-voltage system, the fitting 2 'is then thermally attached to a loaded with large currents current conductor, while the metal vessel held on the fitting 2 can be connected to a located at ground potential and the removal of heat metal encapsulation. The high-voltage insulator is then a cooling element, which removes heat from the power conductor in the serving as evaporator metal fitting 2 'by evaporation of liquid working fluid, which is dissipated by condensation of the vaporized working fluid at the serving as a condenser, cooled metal vessel to the outside.

The two support rings 10, 10 'are identical. As in Figure 3 When the support ring 10 is shown, the support rings 10, 10 'each contain on its outer side a fitting at the end of the insulating 1 conical adhesive surface 11 and an adjoining cylindrical guide surface 12. It is evident on the inside each have a fitting at the pipe end cylindrical surface thirteenth on which sealing and guiding function is fulfilled. The surfaces 11, 12 and 13 are formed by machining, such as turning and / or grinding, in the support rings 10, 10 '.

Also, with the support rings 10, 10 'bonded parts of the metal fittings 2, 2' are identical. As in the FIGS. 2 to 4 is shown in the metal fitting 2, they each contain a paragraph 22, in which a guided around the axis of the insulating tube 1, annular groove 23 is formed. This groove 23 has two coaxial arrangement mainly along the axis A aligned flanks on. The outer flank carries a sealing surface 24 centering the support ring 10. The outer flank carries a cylindrical adhesive surface 25 extending into the base of the groove 23. Above the adhesive surface 25, a plurality of circumferentially uniformly distributed ventilation openings 26 are guided predominantly radially outward through the metal fitting 2 , At the end facing away from the groove bottom end of the outer edge of the support ring 10 centering, cylindrical guide surface 27 is formed in the metal fitting 2 above the vent openings 26.

Fig. 4 It can be seen that the adhesive surfaces 11 and 25 extend into the bottom of the groove 23 and annularly guided about the axis A bond line 30 which is filled vacuum-tight with a set adhesive layer. Since the adhesive surface 11 widens conically upwards from the bottom of the groove 23 and since the adhesive surface 25 is cylindrical, the cross section of the adhesive joint 30 decreases from the bottom of the groove 23 to the ventilation openings 26. In at least one of the adhesive surfaces 11, 25, at least one predominantly circumferentially extending rib 28 (in Fig.2 dashed lines indicated) be formed.

To manufacture the high voltage insulator, the metal fitting 2 - as in Fig.2 shown - clamped so that the annular groove 23 is aligned horizontally and accessible from above. Into the groove is using a in Fig.2 schematically shown static mixer 31 liquid adhesive 32, for example, a two-component adhesive based on an epoxy, introduced into the annular groove 23 and distributed uniformly over the entire circumference of the groove. For a typical 40 to 60 mm diameter insulating tube used for high voltages of 10 to 30 kV, typically 2 to 3 ml of adhesive are introduced into the groove.

How out Figure 3 it can be seen, then the insulating tube 1 is inserted in the direction of an arrow 33 from above into the metal fitting 2 and grouted with the metal fitting to form the joint. When grouting the free end portion of the support ring 10 penetrates into the groove 23 a. The two guide surfaces 12 and 13 of the support ring 10 slide here on the corresponding guide surfaces 24 and 27 of the metal fitting 2 and ensure that the insulating tube 1 is centered. Once the free end portion of the support ring 10 penetrates into the adhesive 32, the support ring 10 acts as a displacement body and presses the adhesive upwards. Because the Guide surfaces 13 and 24 are formed as sealing surfaces and when sliding together form a seal for the adhesive 32, the displaced adhesive 32 is pressed from the bottom of the groove along the adhesive surfaces 11 and 25 in the adhesive joint. Excess glue and air escape through the ventilation openings 26 connected to the adhesive joint to the outside.

Once the support ring strikes, for example, with its free end to the metal fitting 2, the joining and displacement process is completed and is then - as in Figure 4 shown - the adhesive joint 30 completely filled with adhesive. After curing at elevated temperature, typically 60 to 90 ° C, a bond is achieved, which is characterized by a high mechanical tensile shear strength of typically 20 [N / mm ² ] and a good vacuum tightness with a leakage rate of less than 10 ^-9 [mbar l / s]. Since the excess adhesive in the joining and displacement process in the vents 26 through the metal fitting 2 passes out through the penetration of adhesive into an above the openings 26 arranged air-filled annulus, through the free end of the metal fitting 2 and the insulating 1 is limited, avoided. By suitable measures, such as a defined, radially extended and circumferentially guided around the axis A air gap between the insulating tube 1 and the free end of the metal fitting 2 and by forming the free end of the metal fitting 2 as field-controlling bead, the electric field in the dielectric critical Annulus controlled and unwanted electrical partial discharges can be effectively avoided.

A good distribution of the adhesive 32 in the joint 30 and thus a void-free, set adhesive layer is achieved in that the adhesive before Grouting, such as by turning the valve 2 and mixer 30 against each other, is introduced particularly uniformly in the groove 23. Due to the fact that the cross-section of the joint in the direction of flow of the liquid adhesive 32 is reduced, the liquid adhesive passes very evenly and without bubbles from the groove bottom into the joint 30. Therefore, a void-free set adhesive layer is achieved at the point of adhesion. In addition, the thickness of this adhesive layer to the end of the support ring 10 increases towards. Unwanted voltage peaks at the end of the insulating tube 1 are so greatly reduced.

By the at least one rib 28 of the diffusion path for penetrating from the outside into the bond 30 moisture and air is extended and significantly reduced the unwanted ingress of moisture and air into the interior of the high-voltage insulator. At the same time thereby also the juxtaposition of a plurality of small air bubbles in the axial direction is avoided in the adhesive, whereby the quality and density of the adhesive are additionally improved.

In a corresponding manner, the insulating tube 1 can also be glued to the metal fitting 2 '. By this bonding a vacuum-tight cavity is achieved, the only via the support ring 10, respectively. the metal fitting 2 is accessible from the outside.

LIST OF REFERENCE NUMBERS

A

axis

1

insulating

2, 2 '

metal fittings

10, 10 '

support rings

11

adhesive surface

12

guide surface

13

sealing surface

20

external thread

21, 21 '

field electrodes

22

paragraph

23

groove

24

sealing surface

25

adhesive surface

26

vents

27

guide surface

28

rib

30

bonded joint

31

static mixer

32

adhesive

33

arrow

Claims (10)

1. High-voltage insulator with

   - a metal armature (2, 2'),

   - an insulating tube (1) joined to the metal armature, which is adhesively bonded to the metal armature at an end formed as a supporting ring (10, 10'),

   - an adhesive-bonding joint (30), which is disposed around the axis (A) of the insulating tube, is delimited inwardly by a first adhesive-bonding surface (11), arranged on the supporting ring, and outwardly by a second adhesive-bonding surface (25), arranged on the metal armature, and is filled with a hardened layer of adhesive, and with

   - an annular groove (23), which is formed in the metal armature and disposed around the axis of the insulating tube, receives an end portion of the supporting ring and, in coaxial arrangement, has two mainly axially aligned flanks, of which the outer flank carries the second adhesive-bonding surface (25),

   characterized in that the inner flank carries a first sealing surface (24), centering the supporting ring (10), in that a second sealing surface (13) is formed in the supporting ring (10), and in that the first and second sealing surfaces are arranged and formed in such a way that, when the insulating tube (1) and the metal armature (2) are joined, the first sealing surface (24) and the second sealing surface (13) slide on one another, thereby forming a seal, and the supporting ring (10) acting as a displacement body presses adhesive (32) that has been introduced into the groove (23) before the joining into the adhesive-bonding joint (30).
2. Insulator according to Claim 1, characterized in that the end portion of the supporting ring (10) is supported on the base of the groove (23).
3. Insulator according to either of Claims 1 and 2, characterized in that the adhesive-bonding joint (30) extends into the base of the groove (23) and is connected at the end remote from the base of the groove to at least one venting opening (26) that is led through the metal armature (2) to the outside.
4. Insulator according to Claim 3, characterized in that the outer groove flank extends further in the axial direction than the inner groove flank and in that a guiding surface (27) centering the supporting ring (10) is formed on the end of the outer groove flank that is remote from the base of the groove.
5. Insulator according to either of Claims 3 and 4, characterized in that the cross section of the adhesive-bonding joint (30) decreases from the base of the groove to the venting opening (26).
6. Insulator according to Claim 5, characterized in that the first adhesive-bonding surface (11) is of a conical formation and the second adhesive-bonding surface (25) is of a cylindrical formation.
7. Insulator according to one of Claims 1 to 6, characterized in that at least one rib (28) that is made to extend mainly in the circumferential direction is formed in the first adhesive-bonding surface (11) and/or second adhesive-bonding surface (25).
8. Insulator according to one of Claims 1 to 7, characterized in that the metal armature (2') encloses a hollow space that is only open toward the insulating tube (1).
9. Cooling element with a high-voltage insulator according to Claim 8, characterized in that the metal armature (2') is formed as an evaporator.
10. Method for producing a high-voltage insulator with a metal armature (2), an insulating tube (1) and an annular adhesive-bonding joint (30) which is disposed around the axis (A) of the insulating tube and delimited inwardly by a supporting ring (10) of the insulating tube (1) and outwardly by the metal armature (2), in which the insulating tube is joined to the metal armature by introducing an end portion of the supporting ring into an annular groove (23) formed in the metal armature and disposed around the axis of the insulating tube and the joined parts are adhesively bonded to one another, characterized in that, before the joining the groove (23) is filled at least partially with liquid adhesive (32) distributed uniformly in the circumferential direction of the groove, in that during the joining the liquid adhesive (32) is pressed out of the groove (23) into the adhesive-bonding joint (30) by the supporting ring (10) acting as a displacement body, and in that during the pressing operation excess adhesive and air are removed from the adhesive-bonding joint (30) to the outside by way of at least one venting opening (26) led through the metal armature (2).

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