EP1577904A1 - High voltage bushing with element for electric-field control - Google Patents

Abstract

A dielectric bushing (1'), particularly a high-voltage bushing comprises an insulator part (2, 2c) with two installation flanges (4, 8) for installing the bushing. Instead of a screening electrode, a non-linear electric and/or dielectric field control element (9, 9i, 9o) is provided in a field stress zone (7, 7a, 7b). The field control element comprises a matrix, particularly epoxy, silicone, ethylene propylene diene monomer, thermoplast, thermoplastic elastomer or glass. The matrix is filled with microscopic varistor particles, particularly doped zinc oxide particles, titanium oxide particles or stannous oxide particles and/or is filled with high permittivity, particularly with BaTiO 3particles or titanium oxide particles.

Description

TECHNICAL AREA

The invention relates to the field of high or Medium voltage technology, in particular electrical Insulation and connection technology for grounded high-voltage apparatus. It starts from a dielectric Passage and a high voltage electrical apparatus according to the preamble of the independent claims.

STATE OF THE ART

The invention relates to a prior art, such as it is known from WO 02/065486 A1. There will be one High voltage insulator z. B. of porcelain or composite material with a coating of field control material (FGM). The field-controlling coating consists from varistor powder, z. B. from doped zinc oxide (ZnO), which is embedded in a polymer matrix. The FGM coating serves to even out the field distribution on the insulator surface and is distributed so that part of the material with both the ground electrode as well as with the high voltage electrode in electrical Contact stands. In this case, the FGM coating can Cover insulator length only partially and in the field loaded Electrode regions to be concentrated. The FGM coating can be applied to the insulator surface can be incorporated there into a shield be or can by a weatherproof, electrically insulating Protective layer to be shielded to the outside. A Equalization of the capacitive field load can characterized by alternating horizontal stripes or bands FGM coating and insulator material can be realized.

For porcelain insulators, the FGM coating in shape a glaze or a paint applied or in a porridge or mixed in clay, on the porcelain insulator applied and there to a glaze or a ceramic layer be burned. Alternatively, the matrix for the FGM coating a polymer, an adhesive, a Casting compound or a mastic or gel.

EP 1 042 756 describes a glass fiber reinforced insulator tube disclosed on the inner surface and optionally also outer surface is impregnated with a resin, which is a particulate filler with varistor properties, in particular zinc oxide. The GRP pipe can be made by winding a fiberglass net be, at least on the outer layers with the varistor-filled resin is impregnated.

In the book "The Electric Power Engineering Handbook" by LL Grigsby, CRC Press and IEEE Press, Boca Raton (2001), in Chapter 3.13, "Electrical Bushings" by LB Wagenaar, pp. 3-171 to 3-184, various types of electrical feedthroughs are described disclosed. In particular, in FIG. 3.151 a feedthrough with a ground-side shielding electrode arranged inside the insulator tube is indicated. By the shielding electrode, a field control is achieved in the region of the ground-side mounting flange such that the heavily field-loaded zone is field-relieved at the transition from flange to insulator. Such internal shielding electrodes are in pressure gas-insulated bushings, z. B. in SF ₆ -isolated or air-insulated bushings, especially for high voltage level mandatory. Internal shielding electrodes are also known for solid-insulated feedthroughs. However, the shielding electrodes lead to large diameters of the bushings. In addition, only relatively inhomogeneous field controls are achieved with shielding electrodes compared to capacitor bushings with oil or resin impregnated paper. This must be compensated by larger construction heights for the bushings.

The ABB Power Technology Products AB brochure, "SF ₆ -air bushings, type GGA", Technical Guide, 1996-03-30, discloses dielectric feedthroughs equipped with internal shielding electrodes on the ground flange and, for higher voltage levels, also on the voltage-side flange are.

In DE 198 44 409 an insulator is shown, in particular is suitable for dielectric bushings. As usual, the insulator comprises an insulator body Porcelain or composite material and a shield made of Porcelain or silicone. The shield has a variable Insulator screen density on. For field relief in one Isolatorendbereich is turn the known shield electrode between insulator body and conductor available. It is now proposed in the heavily field-loaded Area where the shield electrode ends, an increased number of insulating screens. Due to the increased insulator screen density will provide improved field relief in the End region of the shield electrode achieved.

PRESENTATION OF THE INVENTION

Object of the present invention is to provide an improved dielectric implementation and an electrical High voltage apparatus and an electrical switchgear with indicate such an implementation. This task will according to the invention by the features of the independent claims solved.

The invention consists in a dielectric implementation, in particular a high-voltage bushing for a high voltage electrical apparatus, comprising a Insulator part with a first mounting flange and a second mounting flange for mounting the bushing, wherein within the implementation in a field loading zone in the Area of the first mounting flange one for a desired Voltage level required shielding omitted is and instead for the purpose of field control in the field loading zone a nonlinear electrical and / or dielectric field control element on the insulator part is present in the region of the first mounting flange. Thus, by the invention can be a conventional technical understanding of a specifiable voltage level necessary shielding electrode omitted become. Thereby many advantages are achieved. By Omitting the previously necessary existing inner shielding electrode can dielectric feedthroughs thinner, d. H. be built with reduced diameter. The limit stress, from which a conical broadening to the earth flange is more economical, can to higher Voltage levels are shifted. Cylindrical bushings are cheaper to produce than conical. The Danger of electric flashover between adjacent Feedthroughs is reduced and adjacent phases can be arranged closer to each other or to the earth. Finally, by the inventive field relief by field control material in the flange area a achieved better field control than by the conventional used shielding electrode. The bushings can therefore be built shorter. Especially with pulse load In fact, the electric field is no longer in the range the shielding electrode is concentrated during the entire pulse duration, but can act as a wave along the Spread out the field control and remove it. In addition are reduces the maximum field strengths.

In a first embodiment, the field control material in terms of its nonlinear electrical and / or dielectric properties, its geometric Shape and its arrangement on the insulator part for the dielectric relief of the field loading zone without Shielding electrode for all operating conditions, in particular for surge voltages, designed. The field control can thus also the most critical field loading conditions without Master shielding electrode or shielding electrodes.

In claim 3, design criteria for electrical design of the field control material indicated by a advantageous field control can be realized.

In claim 4 and 5 design criteria for geometric Design of the field control specified by the with little material cost an advantageous field control is reachable. In particular, a minimal required length of the field control along the Longitudinal extent of the insulator part defined according to claim 5 become. This ensures that the field load especially at surge voltage as a traveling wave propagates along the field control element and so far degrades when reaching the far end of the Field control material no more harmful field strengths can train.

Claim 6 indicates how with the field control on Simple way DC feedthroughs are built can.

The embodiment according to claim 7 has the advantage that in particular the highest field loads in the range the Erdflansches with the field control material manageable are.

The embodiments according to claim 8 and 9 have the Advantage that both flange regions through the field control materials independently from rollovers or Partial discharges are protected.

Claim 10a gives various radial positions to the arrangement of the field control material on the insulator part. claim 10b has the advantage that a conventional GRP pipe (fiberglass reinforced plastic) or a conventional one Porcelain insulator by a self-supporting FGM pipe (Field control material tube) is replaceable.

Claim 11 gives advantageous material components for the Field control.

Claims 12 and 13 relate to a high voltage electrical apparatus and comprising an electrical switchgear an inventive implementation with the above Benefits.

Further embodiments, advantages and applications of the invention arise from dependent claims as well as from the Now following description and the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1a, 1b

show in cross-section conventional high-voltage bushings according to the state of Technology;

Fig. 2a-2d

show in cross-section embodiments of a FGM bushing for a GRP pipe with silicone shielding and

Fig. 2a

a continuous FGM coating

Fig. 2b

an earth-side FGM coating

Fig. 2c

each one independent earth-side and high-voltage side FGM coating and

Fig. 2d

an inside and outside FGM coating;

Fig. 3a-3b

show in cross section and in plan embodiments an FGM implementation for one Porcelain insulator with inside and optional exterior FGM coating;

Fig. 4

shows in cross section an embodiment for a self-supporting field control with a Silicone rubber sheds;

Fig. 5

shows electrical energy calculated for lightning surges Surface field distributions E (x) as Function of the location coordinate x along the Implementation and as a function of time for conventional bushings (a, b, c) and for an inventive FGM implementation (D, E, F, G); and

Fig. 6

shows an unfavorable field distribution E (x) if the length is too short or the conductivity too high the FGM coating.

In the figures, the same parts are given the same reference numerals Mistake.

WAYS FOR CARRYING OUT THE INVENTION

Fig. 1a shows a conventional gas-insulated dielectric feedthrough 1, in particular a high voltage feedthrough 1 for a high voltage electrical apparatus. The bushing 1 comprises an insulator part 2; 2a, 2b with a first ground-side mounting flange 4 for mounting the bushing 1 on a grounded housing 5 of an electrical apparatus (not shown) and a second voltage-side mounting flange 8 for mounting the bushing 1 to a high voltage part (not shown). The insulator part 2; 2a, 2b has a gas space 20 for an insulating gas 20 in the interior. The gas space 20 contains a dielectrically insulating gas 20, e.g. As air, compressed air, nitrogen, SF ₆ or similar gas. It may also be an isolation space 20 for receiving an insulating liquid 20 may be present. The gas-insulated bushing 1 is thus hollow, typically hollow cylindrical, with an axis 3a, for receiving an electrical part 3 or at least one electrical conductor 3 in the gas space 20. The bushing 1 is usually used to connect the encapsulated electrical apparatus to ground potential 5 at High or medium voltage network. As is known, an internal shielding electrode 6, 6a is necessarily present in order to achieve field relief in the field-loaded zone 7, 7a at the lower ground flange 4 and to reduce or avoid partial discharges and flashovers. The shielding electrode 6, 6a is typically in electrical contact 46 with the ground flange 4. It protrudes into the gas space 20 and tapers generally conically upwards. It indicates the diameter of the bushing 1 in Erdflanschbereich 4. Dashed lines indicated is a further Abschirmelektrode 6, 6b, which may be located in the field-loaded zone 7, 7b at the upper voltage-side flange 8. This too often tapers conically downwards and serves for field control in the field loading zone 7, 7b.

Fig. 1b shows an example of a solid-insulated Procedure 1 according to the prior art. Here is the insulator part 2, 2b as inside full-volume filled resin body 2 executed with an optional shield 2b. The insulator part 2, 2b thus has an insulation space in the interior for a solid insulating material 20. 3b and 3c designate the power connections. The insulator part 2, 2b surrounds the current conductor 3. The field control is again a shielding electrode 6, 6a in the field loading zone 7, 7a on the earth flange 4 and is with this electrically connected via a contact 46.

Figs. 2a-2d and Fig. 3a-3b show embodiments for a gas-insulated or solid-insulated or otherwise isolated dielectric bushing 1 ', in accordance with the invention at least one shielding electrode 6; 6a, 6b without sacrificing dielectric strength or reliability was omitted. Instead of the shielding electrode 6; 6a, 6b is namely for the purpose of field control in the Field loading zone 7; 7a, 7b a non-linear electrical and / or dielectric field control element 9; 9a, 9b; 9i, 9o; 9s on the insulator part 2; 2a, 2b; 2c in the area of the first Mounting flange 4 available. The field control element 9; 9a 9b; 9i, 9o; 9s is used instead of the earlier in the insulator part 2; 2a, 2b; 2c arranged shielding electrode 6; 6a, 6b for the dielectric relief of the field loading zone 7; 7a, 7b. In the following, preferred embodiments discussed.

According to Fig. 2a, the field control element 9 to the dielectric Relief of the field loading zone 7 designed so that the flange region 7 is stress relieved. For this is the field control element 9 in an intermediate layer 22nd between the GRP pipe (fiberglass-reinforced plastic and especially epoxy tube) 2a and the silicone shield 2b arranged in the form of a cylinder jacket-shaped coating 9. In particular, the field control element 9 by any known manufacturing or processing process, z. B. casting, spraying, winding, extrusion o. Ä., be applied to the outside of the GRP pipe 2a.

Preferably, the field control element 9; 9a, 9b; 9i, 9o; 9s on: nonlinear electrical varistor characteristics and in particular a critical field strength, the varistor switching behavior the field control element 9; 9a, 9b; 9i, 9o; 9s characterized; and / or a high dielectric constant ε, in particular ε> 30, preferably ε> 40 and especially preferably ε> 50.

Advantageously, the field control element 9 is in electrical Contact with the first mounting flange 4 and extends over a predeterminable length l along a longitudinal extent x of the insulator part 2; 2a, 2b. It has one predefinable thickness d or thickness distribution d (l) as a function of length l. Preferably, its length l is greater than or equal to a ratio of a maximum to be tested Surge voltage, in particular a lightning impulse, too the critical electric field strength. This design consideration applies with advantage for all embodiments, where the shielding electrode 6a in the Erdflanschbereich 7a through the Field control element 9; 9a; 9i, 9o is replaced.

According to FIG. 2b, the field control material 9, 9i is arranged on an inner side 21 of the GFRP pipe 2a and can additionally help to reduce surface charges there as well. The length l ₁ is chosen here by way of example so that the field control layer 9, 9i is not in electrical contact with the counter flange 8.

According to FIG. 2 c, in addition to the field control element 9; 9a another field control element 9; 9b, which likewise has suitable nonlinear electrical and / or dielectric properties, in particular those as previously described for the field control element 9; 9a, and in addition in a field loading zone 7, 7b in the region of the second mounting flange 8 over a predetermined length l; l ₂ and thickness d or d (l ₂ ) on the insulator part 2; 2a, 2b is present. In particular, the further field control element 9 is used; 9b as a replacement for a shielding electrode 6b in the region of the second, here the upper, mounting flange 8. Here is an example of an arrangement of the field control element 9; 9a including the further field control element 9; 9b is selected in the intermediate layer 22. Preferably, the further field control element 9; 9b in electrical contact with the second mounting flange 8 and / or is the further field control element 9; 9b by a field control material-free zone extending along the longitudinal extent of the insulator part 2; 2a, 2b extends from the field control element 9; 9a separated in the region of the first mounting flange 4.

According to FIG. 2d, a first field control element 9; 9o in the intermediate layer 22 between the GRP pipe 2a and shield 2b and a second field control element 9, 9i on the inner side 21 of the GRP pipe 2a in the Erdflanschbereich 7a be present. This achieves a further improved field control. The first integrated and the second internal field control element 9o, 9i can be made of the same or other field control material and in particular varistor material. The associated thicknesses d _o , d _i and lengths l _o , l _i can be designed individually. By way of example, d _i > d _o and l _i <l _{o are} selected.

Fig. 3a and Fig. 3b show an insulator part 2, 2c of a Porcelain hollow insulator 2c, on the inside 21 equipped with the field control layer 9, 9i. optional can additionally on the outside 23 a field control material coating 9o, z. B. in disjoint horizontal Strip 9o, preferably between insulator screens 2c and in particular in the lower Erdflanschbereich 7a, available be. Overall, therefore, the field control material 9; 9a, 9b; 9i, 9o in a coating or even massive Shape to be present on an inner 21 and / or integrated in an intermediate layer 22 between Components 2a, 2b of the insulator part 2; 2a, 2b and / or on an outer side 23 of the insulator part 2; 2a, 2b; 2c is arranged.

According to FIG. 4, the field control material 9 takes over; 9s one mechanically supporting function. Preferably takes over Field control material 9; 9s in the insulator part 2; 2b the exclusive mechanically self-supporting function, so that a conventional self-supporting plastic pipe 2a omitted can. Such a field control material insulator tube 2; 2b including 9s is especially easy to set up and special thin in diameter.

For DC applications, the field control element 9; 9i, 9s according to FIG. 2a, FIG. 3a and FIG. 4 on the insulator part 2; 2a, 2b; 2c over the entire surface and along a longitudinal extension x of the insulator part 2; 2a, 2b; 2c continuously be present and both with the first mounting flange 4; 8 as well as with the second mounting flange 8; 4 in electrical Standing in contact.

A preferred choice of material for the field control materials 9; 9a, 9b; 9i, 9o; 9s comprises a matrix filled with microvaristor particles and / or high dielectric constant particles. Suitable microvaristor particles are, for example, doped ZnO particles, TiO ₂ particles or SnO ₂ particles. High dielectric constant have z. B. BaTiO ₃ particles or TiO ₂ particles. In the case of ZnO Mikrovaristorpartikeln these are typically sintered in a temperature range of 800 ° C to 1200 ° C. After rupture and optionally sieving of the sintered product, the microvaristor particles have a typical particle size of less than 125 .mu.m. The matrix is chosen application-specific and can, for. Example, an epoxy, silicone, EPDM, thermoplastic, thermoplastic elastomer or glass. The filling of the matrix with microvaristor particles may be, for example, between 20% by volume and 60% by volume.

5 shows calculations of the E field distribution E (x) normalized to a maximum E field E ₀ as a function of the longitudinal coordinate x of the insulator part 2 and the time represented by successive snapshots a, b, c for a conventional implementation 1 with shielding electrode 6 according to FIG. 1 and D, E, F, G for an inventive implementation 1 '. The calculations were made for a SF ₆ 170 kV bushing with GRP pipe 2a and silicone shield 2b according to conventional structure 1 or inventive construction 1 '. FIG. 5 shows the electric field strength E (x) at the silicon-air interface during or shortly after the application of a lightning impulse with time delays of 0.5 μs / 2.2 μs / 20 μs for the curves a, b, c and 0.5 μs / 1.0 μs / 5 μs / 20 μs for the curves D, E, F, G. It can be seen clearly that the new design of the bushing 1 'avoids the E-field peaks and at any time a more homogeneous E field distribution is achieved. In addition, the areas of increased field strength are no longer stationary, which has an advantageous effect on the dielectric behavior of the bushing 1 '. With the help of the field calculations and the nonlinear electrical and / or dielectric properties of the field control element 9; 9a, 9b; 9i, 9o; 9s, the field control design of the implementation 1 'can be optimized.

Fig. 6 shows an insufficient design, wherein the field control element 9; 9a, 9b; 9i, 9o; 9s has too high electrical conductivity or the length l; l ₁ , l _{2 is} too short. As a result, the E-field propagates along the field control layer 9; 9a, 9b; 9i, 9o; 9s, but is not degraded, so that at the end of the field control layer 9; 9a, 9b; 9i, 9o; 9s nevertheless again a field exaggeration occurs, which can lead to partial discharges, flashovers or breakdowns. On the other hand, too low electrical conductivity of the field control material 9; 9a, 9b; 9i, 9o; 9s, the E-field can not be effectively controlled or controlled. For an optimal design of a varistor-like field control element 9; 9a; 9i, 9o; 9s in Erdflanschbereich 7, 7a, the simple but effective rule can be stated that the field control element length l; l ₁ , l _{2 is} greater than or equal to choose a ratio of a surge voltage to the critical electric field strength, the varistor switching behavior of the field control element 9; 9a, 9b; 9i, 9o; 9s characterized.

Uses of the inventive dielectric implementation 1 'relate inter alia. the use as implementation 1 ' in a high voltage electrical apparatus, in particular a disconnector, outdoor circuit-breaker, vacuum switch, Dead Tank Breaker, Current Transformer, Voltage Transformer, Transformer, Power capacitor or cable termination or in an electrical switchgear for high or low Medium voltage. The invention is also a high-voltage electrical apparatus, in particular a disconnector, Outdoor Circuit Breaker, Dead Tank Breaker, Current Transformer, Voltage transformer, transformer, power capacitor or cable termination, wherein a dielectric Implementation 1 'as described above is present. As well is an electrical switchgear, in particular a High or medium voltage switchgear comprising a claimed such high voltage electrical apparatus.

LIST OF REFERENCE NUMBERS

1

Conventional high voltage feedthrough

1'

FGM-high-voltage bushing

2

Self-supporting insulator

20

Isolation (solid, liquid, gel, gaseous), epoxy, foam, oil, air, SF ₆

21

Inside of the insulator part

22

Interlayer of the insulator part

23

Outside of the insulator part

2a

GRP pipe (glass fiber reinforced plastic), glass fiber reinforced epoxy tube

2 B

External insulator, shielding, silicone shielding

2c

porcelain insulator

3

Conductor (at high voltage potential)

3a

central axis

3b

power connection

3c

power connection

4

Flange (grounded), ground flange

46

Contact between flange and shielding electrode

5

Housing of high voltage apparatus

6

shield

6a

Shielding electrode, earthing electrode

6b

Shielding electrode, high voltage electrode

7

Heavily field-polluted zone

7a

Field load zone in Erdflanschbereich

7b

Field loading zone in high voltage flange area

8th

Hochspannungsflansch

9

Field controlling material, FGM, varistor material, field controlling coating

9a

FGM in the earth flange area

9b

FGM in high voltage flange area

9i

FGM on insulator inner surface

9o

FGM on insulator outer surface

9s

self-supporting field-controlling insulator tube

a

conventional implementation, after 0.5 μs

b

conventional implementation, after 2.2 μs

c

conventional implementation, after 20 μs

D

FGM implementation, after 0.5 μs

e

FGM implementation, after 1.0 μs

F

FGM implementation, after 5 μs

G

FGM implementation, after 20 μs

d, d (l)

Thickness of the field controlling coating or the field controlling tube

d _i , d _o

Thickness of field controlling inner layer or outer layer

l

Length of field-controlling coating or the field controlling tube

l ₁ , l ₂

Length of the field-controlling coating in the Erdflanschbereich or high voltage flange area

Ex)

electric field distribution along high voltage feedthrough

E _o

maximum electric field, normalization field

x

Location coordinate along the longitudinal extent of the FGM implementation

Claims (13)

Dielectric feedthrough (1 '), in particular high voltage leadthrough (1') for a high voltage electrical apparatus, comprising an insulator part (2; 2a, 2b; 2c) having a first mounting flange (4; 8) and a second mounting flange (8; 4) for mounting the implementation (1 '), characterized in that a) within the feedthrough (1 ') in a field loading zone (7; 7a, 7b) in the region of the first mounting flange (4; 8) a shielding electrode (6; 6a, 6b) required for a desired voltage level is omitted, and b) instead, for the purpose of field control in the field loading zone (7; 7a, 7b), a nonlinear electrical and / or dielectric field control element (9; 9a, 9b; 9i, 9o; 9s) on the insulator part (2; 2a, 2b; 2c) in FIG Area of the first mounting flange (4; 8) is present. The bushing (1 ') according to claim 1, characterized in that the field control element (9; 9a, 9b; 9i, 9o; 9s), with regard to its nonlinear electrical and / or dielectric properties, its geometric shape and its arrangement on the insulator part (2; 2a, 2b, 2c) for the dielectric relief of the field loading zone (7, 7a, 7b) without screening electrode (6, 6a, 6b) is designed for all operating states, in particular for surge voltages. The bushing (1 ') according to any one of the preceding claims, characterized in that the field control element (9; 9a, 9b; 9i, 9o; 9s) comprises: a) nonlinear electrical varistor characteristics and in particular a critical field strength which characterizes a varistor switching behavior of the field control element (9; 9a, 9b; 9i, 9o; 9s), and / or b) a high dielectric constant ε, in particular ε> 30, preferably ε> 40 and particularly preferably ε> 50. The bushing (1 ') according to one of the preceding claims, characterized in that the field control element (9; 9a, 9b; 9i, 9o; 9s) is in electrical contact with the first mounting flange (4; 8) over a predeterminable length (l; l ₁ , l ₂ ) extends along a longitudinal extension (x) of the insulator part (2; 2a, 2b; 2c) and has a predeterminable thickness (d) or thickness distribution (d (l)) as a function of the length (1; ₁ , l ₂ ). The bushing (1 ') according to claim 3a and 4, characterized in that the length (l; l ₁ , l ₂ ) is greater than or equal to a ratio of a maximum test voltage to be tested selected to the critical electric field strength. The bushing (1 ') according to claim 3a and optionally claim 4, characterized in that the field control element (9; 9i, 9s) for DC applications on the insulator part (2; 2a, 2b; 2c) over the entire surface and along a longitudinal extent (x) of the insulator part (2; 2a, 2b; 2c) is continuous and in electrical contact with both the first mounting flange (4; 8) and the second mounting flange (8; 4). The bushing (1 ') according to one of the preceding claims, characterized in that a) the first mounting flange (4) is an earth-side mounting flange (4) for mounting the bushing (1 ') on a grounded housing (5) of an electrical apparatus and / or b) the second mounting flange (8) is a voltage-side mounting flange (8) for mounting the bushing (1 ') to a high voltage part and / or c) the insulator part (2; 2a, 2b; 2c) has inside an insulation space for a solid insulation material (20) or for an insulation liquid (20) or a gas space for an insulation gas (20). The passage (1 ') according to claim 7a and 7b, characterized in that a) a further field control element (9; 9b) is present, which has suitable nonlinear electrical and / or dielectric properties, in particular those according to claim 3, and in a field loading zone (7; 7a, 7b) in the region of the second mounting flange (8; ) over a predeterminable length (l; l ₂ ) and thickness (d, d (l ₂ )) on the insulator part (2; 2a, 2b, 2c) is arranged and b) in particular that the further field control element (9; 9b) serves as a replacement for a shielding electrode (6b) in the region of the second mounting flange (8; 4). The passage (1 ') according to claim 8, characterized in that a) the further field control element (9; 9b) is in electrical contact with the second mounting flange (8; 4) and / or b) the further field control element (9; 9b) is guided by a field control material-free zone which extends along the longitudinal extent of the insulator part (2; 2a, 2b) from the field control element (9; 9a; 9i, 9o) in the region of the first mounting flange (4; 8) is separated. The bushing (1 ') according to one of the preceding claims, characterized in that a) the field control element (9; 9a, 9b; 9i, 9o; 9s) is present in a coating or solid shape which is integrated on an inner side (21) and / or in an intermediate layer (22) between components (2a, 2b) the insulator part (2; 2a, 2b) and / or on an outer side (23), in particular there in disjoint horizontal strips (9o), of the insulator part (2; 2a, 2b; 2c) is present and / or b) the field control element (9; 9a, 9b; 9i, 9o; 9s) assumes a mechanically supporting function and in particular that the field control material (9; 9a, 9b; 9i, 9o; 9s) in the insulator part (2; 2a, 2b; 2c ) assumes the exclusive mechanical self-supporting function. The bushing (1 ') according to one of the preceding claims, characterized in that the field control element (9; 9a, 9b; 9i, 9o; 9s) comprises a matrix, in particular an epoxy, silicone, EPDM, thermoplastic, thermoplastic elastomer or glass and the matrix a) is filled with Mikrovaristorpartikeln, in particular doped ZnO particles, TiO ₂ particles or SnO ₂ particles, and / or b) is filled with particles with high dielectric constant, in particular with BaTiO ₃ particles or TiO ₂ particles. Electrical high-voltage apparatus, in particular isolator, outdoor circuit breaker, vacuum switch, dead tank breaker, current transformer, voltage transformer, transformer, power capacitor or cable termination, characterized in that a dielectric bushing (1 ') according to one of the preceding claims is present. Electrical switchgear, in particular high or medium voltage switchgear, characterized by a high voltage electrical apparatus according to claim 12.

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