WO2017055020A1

WO2017055020A1 - Particle trap for a gas-insulated system, and gas-insulated system comprising a particle trap

Info

Publication number: WO2017055020A1
Application number: PCT/EP2016/070944
Authority: WO
Inventors: Thomas Berg; Tom FEDTKE; Mario Kieper; Alexander ROSE-PÖTZSCH
Original assignee: Siemens Aktiengesellschaft
Priority date: 2015-09-29
Filing date: 2016-09-06
Publication date: 2017-04-06
Also published as: EP3335286A1; DE102015218728A1

Abstract

The invention relates to a particle trap (4) for a gas-insulated electric system (1), comprising a shield (412, 422) which is made of a conductive material and by means of which a weak field strength region (414, 424) in an interior of the gas-insulated system (1) can be limited by forming particle inlet openings (415, 425). The invention is characterized in that a field strength gradient along a shield outer surface (416, 426) facing away from the weak field strength region does not exceed a specified gradient maximum value. The invention further relates to a gas-insulated system (1) comprising the particle trap (4) and to a high-voltage transmission system (35) comprising a converter (36) for transmitting electric power, said converter being connected to an AC voltage grid on the AC voltage side and to a DC voltage line on the DC voltage side. The DC voltage line is a gas-insulated line (1) comprising the particle trap (4) according to the invention.

Description

description

Particle trap for a gas-insulated system and gas-insulated system with particle trap

The invention relates to a particulate trap for a gasiso ^¬ profiled electrical system with a shield of a conductive material, by means of the formation of a low field strength range in an interior of the gas insulated apparatus under exclusion be limited by particle inlet openings.

Particulate traps are used in gas-insulated electrical installations, especially in gas-insulated lines (GIL) and switchgear (GIS), to minimize damage that can be caused by freely moving conductive particles. Due to abrasion during installation or due to vibrations of the gas-insulated system, such freely moving particles can be released in an interior of the system. These particles have a significant impact on the ability Isolierfä- the gas insulated apparatus and can particularly greatly reduce the dielectric strength of the system such as by part ^¬ discharges due to particle-induced field increases. A species-appropriate particle trap is known from US 3,515,939 A ^¬ be known. The known particle trap is such arranged in a gasiso ^¬ profiled line, that the shielding an area of weak field strength sometimes limited. In this Be ^¬ rich is the electric field strength in comparison to the electric field strength outside the range of several

Orders of magnitude weaker, so that the force acting on particles therein is insufficient to lead them out of the field-weak area. Free-moving particles in the line undergo a movement due to an electric field present in the line, for example an alternating field. Due to this movement, the particles through the particle inlet openings in enter the field strength weak area. In the most favorable case, the particles subsequently remain there. In this way damage by partial discharges in the line can be avoided by means of the known particle trap.

The object of the invention is to provide an input ge ^¬ mentioned particulate trap, their protective effect is improved over the above-described damage. The object is achieved in that a field strength gradient along a side of the shielding surface facing away from the field strength-weak area has a predetermined value

Does not exceed the maximum gradient value. The invention is based on the insight that to obtain a high protective effect, the floating particles in the gas insulated apparatus controlled as possible must be performed in the field ^¬ strength weak portion. Our own investigations have shown that moving particles are attracted to areas of higher field strength along the outer surface of particle traps. There is therefore on the outer surface of the shield regions where the field strength ge ^¬ genüber the immediate area is particularly high, so the particles can be drawn into these regions. In particular, in an operation of the system with high ^DC voltage, this effect can cause the particles do not reach the field strength weak area of the particle trap, which reduces the protective effect of the particulate trap. Accordingly, the outer surface of the particle trap should have a shape or form which gives the smallest possible differences in the electric field strength along the outer surface, if this is used in a gas-insulated plant. Therefore, such a shaped outer surface ^¬ is desirable that the field strength gradient along the outer surface, ie, the local change in the electric field strength at the outer surface in each predetermined Rich ^¬ processing with a predetermined geometry of the plant, possible minimal is. This can be achieved by the field strength gradient below a predetermined threshold, the

Gradient maximum value remains. Thus may advantageously be changed verhin ^¬ that the initially located outside the area feldschwa- chen particles by electrical forces due to a high field strength gradients of the

Move the particle inlet openings away and do not reach the field-weak area. The gradient maximum value is determined as a function of the geometry of the system and of the voltage applied there.

As is known, the electric field strength is particularly high at points of high curvature. The curvature at a point of a surface can be described by a radius of curvature at this point, the surface on which the curvature is inversely proportional: the larger the (local) radii of curvature ^¬ us r, the smaller the curvature k, k ~ 1 / r , According to a preferred embodiment of the invention, the curvature of the outer surface of the shield does not exceed a predetermined maximum curvature. Accordingly, the outer ^¬ surface is shaped such or their Krümmungsra ^¬ dius always chosen such that a small curvature un ^¬ terhalb result of the curvature of maximum value. Preferably, the particulate trap comprises a foot connected to the shield for attaching the particulate trap to an outer tube or to an inner conductor of the gas-insulated abutment, the outer surface of the shield having a convex radial contour with respect to the foot. The particle trap suitably has a longitudinal direction, which coincides with a An ^¬ order of the particle trap in the gas-insulated system with a longitudinal axis of the plant. A plane perpendicular thereto may then be referred to as the radial cross-sectional plane. The radial contour designates the one-dimensional contour of the outer surface in a section through the

Particle trap along the radial cross-sectional plane. A with respect to the foot convex radial contour denotes the Case, that a straight line piece, which is drawn between two points of the outer surface, always on the field-weak area facing side of the outer surface extends. The ^¬ against a concave radial contour would force a profile on the side remote from the frame side weak portion. The convex contour of the outer radial surface has in part the on ^¬ that in particular a high curvature may be avoided at end portions of the outer surface. In addition, it can be avoided that particles are retained on the outer surface of the particle trap due to gravity, because they can not enter the field-weak region against the force of gravity via the concave edge of the outer surface. Particularly preferably, the shield is curved in such a way that a shield end of the shield facing away from the foot is angled towards the foot. This has the advantageous effect that a tip, which possibly forms on the shield end, is already in the field-weak area, so that a high field strength gradient is avoided at the shield end. As part of the invention, different particularly advantageous forms the outer surface of the particle trap were it averages ^¬.

Accordingly, according to a preferred embodiment of the invention, the outer surface has an at least partially oval-shaped radial contour. The outer surface thus ent ^¬ speaks in its radial contour of a part of an ellipse. According to a further preferred embodiment, the outer surface at least in the region of

Particle inlet openings on an at least partially wendei ^¬ shaped radial contour. For example, the Krüm ^¬ mung the outer surface increases towards the outer ones of the exhaust shield. In this way, the curvature is lowest in the area of the greatest probability of residence for freely moving particles, if the particle trap is, for example, wise on the outer tube of the system in its lowest point, that is, for example, in the case of a gas-insulated pipe centrally below the inner conductor, is arranged. Due to the wen ^¬ delliform outer surface of the field strength gradient along the outer surface is almost constant and can be small ge ^¬ chooses, since the curvature increases uniformly along the outer surface.

According to one embodiment of the invention, the outer surface has an at least partially rectilinear radial Kon ^¬ tur. This can be particularly advantageous because the Krüm ^¬ tion of a flat surface is zero and thus is particularly small. Preferably, the particle trap forms at least two partial ^¬ falls, wherein the at least two partial traps of

Particle trap are arranged to each other such that einan ^¬ the facing surfaces of the partial traps limit by mutual field influence at least one further feldstärkeschwa- chen area. It can be advantageously achieved in this way that any unavoidable edges or sections of high curvature are already arranged on the mutually facing sides of the sub-traps in the further field-weak-field region, so that the particles do not stick there.

The invention further relates to a gas-insulated electrical Anaige with an inner conductor and an inner tube enclosing the outer tube.

Such a gas-insulated system is known for example from the already mentioned document US Pat. No. 3,515,939 A.

The object of the invention is to provide such a profiled gas- conditioning, wherein the damage caused by the free ^¬ be moveable particles are avoided. The object is achieved in a gas-insulated plant according to the art in that a fiction, ^¬ particulate trap is placed in the outer tube of the plant.

The advantages of the gas-insulated system according to the invention result from the advantages of the previously described

Particulate trap. Depending on the polarity of the voltage in the gas insulated apparatus different arrangements of the particulate trap be ^¬ Sonders may be advantageous.

According to one embodiment, the particulate trap is connected to the outer tube. This is particularly advantageous if the polarity is positive, that is, when the inner conductor is located relative to the outer tube at a positive potential, for example when the inner conductor lying on a positi ^¬ ven potential and the outer tube at ground potential. In this case, the particle trap is particularly preferably arranged under ^¬ half of the inner conductor, since there the stay ^¬ probability for the particles is the highest.

According to a further embodiment, the particle trap is connected to the inner conductor. This is particularly advantageous when ei ^¬ ner negative polarity of the gas insulated apparatus, because the highest probability is for the Parti ^¬ kel on the inner conductor, in particular a bottom of the In ^¬ nenleiters.

Preferably, the inner conductor is hollow and the particle trap connected to the inner conductor, so that the field strength weak area is at least partially limited by Innenlei ^¬ ter. This results in a particularly simple execution tion of the particle trap, in which the homogeneity of the field trials ^¬ distribution is disturbed in the system only slightly. Preferably, the inner conductor of the gas-insulated system is arranged concentrically in the outer tube. According to this symmetrical arrangement, all radial distances between inner conductor and outer tube are the same, so that the insulating capability of the gas-insulated system is particularly high (in particular against ^¬ over an eccentric arrangement of the inner conductor).

The plant is preferably a GIL or a GIS. The A ^¬ rate of the particulate trap according to the invention at a GIL or GIS is particularly advantageous because there can with floating particles in connection problems are most prevalent. The resulting physical mechanisms and effects are basically the same in GIL and GIS.

The invention further relates to a high-voltage direct-current transmission system with a converter for transmitting elekt ^¬ cal power, the AC side is connected to an AC voltage network and the DC voltage side with a DC voltage line.

Such a high-voltage direct-current transmission system is known from the prior art, for example from WO

2011/006796 A2 known. It is mostly used to transmit electrical power over long distances of more than 100 km. The voltage is usually oberhalbt of 100 kV in the DC ^¬ line.

The object of the invention is to propose such a high-voltage ^direct- current transmission system which allows ei ^¬ NEN error-free operation.

The object is achieved in a type Hochspannungsgleich- current transmission system in that at least a portion of the DC voltage line is a gas-insulated line with the particulate trap according to the invention. The advantages of the high-voltage direct-current transmission system according to the invention result from the previously described advantages of the particle trap according to the invention in conjunction with the gas-insulated line.

The invention will be explained in more detail below with reference to Figures 1-11.

FIG. 1 shows an exemplary embodiment of a gas-insulated electrical system according to the invention in a schematic axial cross-sectional representation;

Figure 2 shows a section of the gas-insulated plant of

FIG. 1 shows an exemplary embodiment of a particle trap according to the invention in a schematic axial cross-sectional view;

Figure 3 shows a second embodiment of a erfin ^{¬ to the} invention particulate trap in a schematic axial cross-sectional view;

Figure 4 shows a third embodiment of a particulate trap OF INVENTION ^¬ to the invention in a schematic axial cross-sectional view;

Figure 5 shows a fourth embodiment of a particulate trap OF INVENTION ^¬ to the invention in a schematic axial cross-sectional view; Figure 6 shows a fifth embodiment of a particulate trap OF INVENTION ^¬ to the invention in a schematic axial cross-sectional view;

Figure 7 shows a sixth embodiment of a particulate trap OF INVENTION ^¬ to the invention in a schematic axial cross-sectional view; Figure 8 shows a seventh embodiment of an OF INVENTION ^¬ to the invention the particulate trap in a schematic axial cross-sectional view; Figure 9 shows a second embodiment of an OF INVENTION ^¬ to the invention gas-insulated electrical installation in a schematic axial

Cross-sectional illustration, · Figures

10, 11 each show an embodiment of a erfin ^{¬ to the} invention particulate trap in an inner conductor of a gas-insulated system according to the invention in a schematic axial cross-sectional view;

Figure 12 shows an embodiment of an inventive ^¬ SEN high-voltage DC transmission system in a schematic representation. FIG. 1 shows a gas-insulated system according to the invention in the form of a gas-insulated line 1. The gas-insulated line 1 comprises an outer tube 2 and an inner conductor 3, which is formed in the illustrated embodiment as Hohllei ^¬ ter. The inner conductor 3 is arranged coaxially in the outer tube 2, wherein a center of the circular cross section of the inner conductor 3 coincides with a center of the circular cross section of the outer tube 2.

Both the inner conductor 3 and the outer tube 2 are made of a conductive material and extend ent ^¬ long a longitudinal direction transverse to the plane of the figure 1. Below the waveguide 3, a particulate trap 51 is in the outer tube 2 and connected to it. Another particulate trap 52 is formed by the inner conductor 3 itself. To this end, the inner conductor 3 forms a Abschir ^¬ mung having a field strength weak portion 6 inside the Inner conductor 3 limited. Furthermore, the inner conductor 3 has a particle inlet opening 7. By the

Particle inlet opening 7 can move freely movable particles in the outer tube 2 in the field strength weak area 6.

During operation of the gas-insulated line 1, the inner conductor 3 is at an electrical potential, which differs from an electric potential of the outer tube 2, usually by several hundred kV. In the positive polarity of the inner conductor 3 is at a positive potential, whereas the outer tube 2 is, for example on a ground potential or a nega tive ^¬ potential. The inner conductor 3 is of negative polarity entspre ^¬ accordingly at a negative potential, whereas the outer tube 2 is at a ground potential or a positive potential. Be replaced by vibration or abrasion freely movable conductive particles from the outer tube 2 and the inner conductor 3 or by not shown in Figure 1 the support insulators of the gas-insulated line, these particles may have an undesirable reduction in Durchschlagfes ^¬ ACTION the gas-insulated line 1 to bring about through line transport and line output. If the polarity is positive, these particles can be attracted by the outer tube 2. With negative polarity, these particles can be attracted to the inner conductor 3. Moreover, always acts the weight of which has a magnificent P ^¬ designated direction, namely downwards in Figure 1, the freely moving particle kel. Taking into account the force of the electric field and the weight acting on the particles, the

Particle traps 51, 52 are arranged in spatial areas where the probability of residence for the particles is greatest (given polarity).

Considering the particulate trap 51 which is arranged below the inner ^¬ conductor 3 and connected to the outer tube 2, so are in the interior 8 of the gas-insulated line 1 located freely movable particles first move once on a Au ^¬ ßenoberfläche 9 of the particulate trap 51. From there should the particles are controlled as possible in a feldstärkeschwa ^¬ chen area in the gas-insulated line 1 out. Subsequently, the particles should remain there. The situation is similar with negative polarity. In this case, the freely movable particles initially run on an outer surface 10 of the particle trap 52 and are to be guided from there through the particle inlet opening 7 into the field strength-weak area in the interior of the inner conductor 3. In this way damage that can be caused by the particles can be avoided.

FIG. 2 shows a detail of a particle trap 4 in a detailed axial cross-sectional representation. The particle trap 4 comprises two partial traps 41 and 42, which are arranged symmetrically relative to each other with respect to an axis 11. Both partial traps 41 and 42 extend along the longitudinal axis of the gas-insulated line 1 transversely to the plane of the drawing of FIG. 2. The partial trap 41 comprises a foot 411 for connecting the partial trap 41 to the outer tube 2 of the gas-insulated line. Furthermore, the partial trap 41 comprises a shield

412 connected to the foot 411. The shield 412 defines, together with the foot 411 and a portion 413 of the outer pipe 2 of the gas-insulated line 1 has a field strength weak portion 414. Since the particulate trap 9 is made of a guiding material capable of and to the outer tube 2 ver ^¬ connected is located the particle trap 4 and in particular, the shield 412 at the same potential as the outer tube 2. For this reason, the electric field in the field ^¬ weakest region 414 by several, in the present example by about 2 powers smaller than outside the field strength weak area. Freely moving particles in the outer tube 2 of the gas-insulated line 1 can by a

Particle entry opening 415 enter the field strength weak area 414. On the low field strength region 414 from the side of the shield 412, an outer surface 416 of the shield 412 is formed. According to the first partial trap 41, the second partial ^trap 42 has a foot 421, a shield 422, a field strength weak area 424, a

Particle inlet opening 425 and an outer surface 426 of the shield 422. Due to the arrangement of the two partial traps 41 and 42 form the second part of trap 42 facing side 417 of the first part of trap 41 and the first Teilfal ^¬ le 41 facing side 427 of the second part of trap 42 another field strength weak Area 12.

It can be seen that the radial contour of the outer surface 426 is formed helically at an end 428 remote from the foot 421, so that the curvature of the outer surface 426 increases uniformly towards this end 428. In this way, the field strength gradient along the outer surface 426 is low. Accordingly, the outer surface 416 of the first part of trap 41 is also wideniförmig sections ausgebil ^¬ det. The electric field generated by the first partial trap 41 and the electric field generated by the second partial trap 42 in the outer tube 2 influence each other, so that there the field strength weak area 12 between the partial traps 41 and 42 is formed. The shield 412 of the first partial trap 41 forms an overhang 419 on its inner side 417. The shield 422 of the second partial trap 42 forms on its inside arranged side 427 an overhang 429. By the formation of the overhangs 419 and 429 of the wide ^¬ re field strength weak portion is provided with two recesses 430 and 431 12th These indentations 430 and 431 make it more difficult, in addition, that freely moving particles leave the field strength ^¬ weak portion 12th

In the following FIGS. 2 to 9, identical and similar elements of the particle traps represented there are provided with the same reference numerals. For clarity, therefore, in the description of the embodiments The particle traps of Figures 3 to 9 are discussed in more detail only on their differences.

Figure 3 shows a second embodiment of a

Particle trap 13. In contrast to the particulate trap 4 of Figure 2, the internally disposed sides 417 and 427 of the partial traps 41 and 42 of the particulate trap 13 are flat. This simplifies the production of the particle trap, since its shape does not have any overhangs.

FIG. 4 shows a further exemplary embodiment of a

Particle trap 14. The particle trap 14 similar to the particle trap 13 of Figure 3 includes a first and a second part ^¬ trap 41 and 42. In contrast to the particle trap 13, the partial traps 41 and 42 are arranged further apart. Between the first and the second partial trap 41 or

42, a third sub-trap 43 is arranged. The third part ^trap 43 comprises a foot 431 for connecting the third part catch 43 to the outer tube 2. The foot 431 of the third part catch 43 merges with its end facing away from the outer tube 2 into a shield 432 which has a rounded outer surface 433. Between one of the third partial trap

43 facing side of the first part of the trap 41 and the first part of the trap 41 facing side of the third part of the trap 43, a first additional field strength weak area 121 is formed. Between the mutually facing sides of the third part of the trap 43 and the second part of the trap 42, a second additional feldstärkeschwacher region 122 is formed.

In Figure 5 is a fourth embodiment of a

Particle trap 15 shown. In contrast to

Particle trap 4 of Figure 2, the foot 411 of the first part ^¬ trap 41 and the foot 421 of the second part of the trap 42 are connected to each other and only at individual points in the longitudinal direction of the particle trap 15 connected to the outer tube 2, which is indicated in Figure 5 in that foot 411 and foot 421 are shown by a broken line. By a comparison with the particle trap 4 narrower version of the shields 412 and 422, the corresponding field strength weak areas 414 and 424 are increased. This reduces the likelihood of re-emergence of the particles from low field strength regions 414 and 424.

Figure 6 shows a fifth embodiment of a

Particle trap 16. The particulate trap 16 includes a foot 161 for connecting the particulate trap 16 to the outer tube 2 and a shield 162. The shield 162 has an outer surface 163. It can be seen that the radial contour of the outer surface 163 shown in FIG. 6 has a partially oval shape.

The shield 162 has a first and a second shield end 164 or 165 facing away from the foot 161. The shield ends 164 and 165 each have a tip 166 and 167, respectively. The tips 166 and 167 are angled toward the foot 161, respectively. As a result, the peaks 166, 167 are located within the low field intensity regions 168 and 169, thereby avoiding a high field strength gradient value at the peaks 166, 167. In contrast to the particle trap 16 of FIG. 6, the sixth exemplary embodiment of a particle trap 17 according to the invention is connected to the outer tube 2 only at individual points in the longitudinal direction of the particle trap 17, which is indicated in FIG. 5 by a representation of the foot 161 by means of a broken line is.

A seventh embodiment of an inventive

Particle trap 18 is shown in FIG. The

Particle trap 18 has a foot 181 for connecting to the outer tube 2 and a shield 182. In addition to the particle trap 18, which is arranged centrally below the inner conductor 3, not shown graphically in FIG. two further particle traps 19 and 20 are provided. The other particulate traps 19 and 20 are each constructed similar to the particulate trap 18 and reasonable along the periphery of Au ^¬ ßenrohres 2 either side of the particulate trap 18 arranged.

Figure 9 shows a schematic representation of an eighth From ^¬ guidance example of a particulate trap 21 according to the invention in a gas-insulated pipe 1 with an inner conductor 3 and an outer pipe 2. The particulate trap 21 includes a first Ab ^¬ shielding 22 and a second shield 23, the straight a ^{¬ have} linear radial contour. The shields 22 and 23 are arranged offset from one another in such a way that a particle inlet opening 24 is formed through which particles can pass into an area 25 which is weak in field strength and limited by the shields 22 and 23 and the outer tube 2. This embodiment has the advantage that the

Particle trap 21 has a particularly simple structure. FIG. 10 shows a particulate trap 31 according to the invention in accordance with a ninth embodiment. The particle trap 31 is formed by the inner conductor 3 of a gas-insulated line, in which a particle inlet opening 312 is provided. The inner conductor 3 is embodied as a waveguide and delimits a field strength weak region 313 and thus simultaneously forms a shield 315 of the particle trap 31. The particle trap 31 has an outer surface 314 whose radial contour is profiled close to the particle inlet opening 312 such that the field strength gradient along the outer surface is as small as possible.

Figure 11 shows a further embodiment of a particulate trap OF INVENTION ^¬ to the invention 32, which is formed by the inner conductor 3 of a gas-insulated line which defines a field strength range keschwachen 324th In contrast to

Particle trap 31 of Figure 10 is the

Particle inlet opening 321 of the particle trap 32 narrower. Opposite edges 322 and 323 of the shield 325 of the particle trap 32 formed by the inner conductor 3 influence the electric field in the region of

Particle inlet opening 321 such that the Feldstärkegra- is there as small as possible.

Figure 12 shows an embodiment of an inventive ^¬ SEN high voltage dc transmission system (HVDC plant) 35 to a converter 36 having a DC side and an AC side. The inverter 36 may be, for example, a grid-connected or a self-commutated inverter. The converter 36 is connected on the alternating voltage side to a three-phase AC voltage line 37 and DC voltage side to a DC voltage line 381 and a ground conductor 382. The DC voltage line 381 is in the illustrated embodiment, a buried GIL in the plurality of particle traps according to one of Figures 1 to 11 are arranged. The HVDC system shown in Figure 12 is used to transfer electrical power between the AC voltage network 37 and another AC voltage network 40. For this purpose, an additional inverter 39 is provided, the DC side connected to the DC voltage line 381 and the AC side with the other AC voltage network 40.

Claims

Particle trap (4) for a gas-insulated electrical An ^¬ position (1) with a shield (412, 422) made of a conductive material, by means of a feldstärkeschwa ^¬ cher area (414, 424) in an interior of the gas-insulated system (1) under training from

Particle inlet openings (415, 425) can be limited, characterized in that a field strength gradient along an outer surface (416, 426) of the shield (412, 422) facing away from the field strength ^¬ weak area a predetermined

Does not exceed the maximum gradient value.

The particulate trap (4) of claim 1, wherein the curvature of the outer surface (416, 426) of the shield does not exceed a predetermined maximum curvature.

A particulate trap (4) according to claim 1 or 2, wherein the particulate trap has a foot (411, 421) connected to the shield (412, 422) for attaching the particulate trap (4) to an outer tube (2) or an inner conductor (3) gas-insulated plant (1) and the outer surface (416, 426) of the shield has a relative to the Fu ^¬ ßes (411, 421) convex radial contour.

Particle trap (16) according to one of claims 1 or 2, where ^¬ in the outer surface (163) has an at least partially oval-shaped radial contour.

Particle trap (4) according to one of claims 1 or 2, where ^¬ in the outer surface (416, 426) at least in the region of the particle inlet openings has an at least partially helical radial contour.

6. Particle trap (21) according to any one of the preceding claims, wherein the outer surface (22, 23) has an at least partially rectilinear radial contour. 7. particulate trap (4) according to any one of the preceding claims, wherein the particulate trap at least two sub-cases (41, 42) forms and the at least two sub-cases (41, 42) of the particle trap (4) are in such relative angeord ^¬ net that facing surfaces (417, 427) of the sub-traps (41, 42) limit by mutual field influence at least one further feldstärkeschwa ^¬ chen area (12).

8. Gas-insulated electrical system (1) with

an inner conductor (3),

a the inner conductor (3) enclosing the outer tube

(2),

marked by

a particle trap (51, 52) arranged in the outer tube (2) according to one of claims 1 to 7.

9. Gas-insulated plant (1) according to claim 8, wherein the

Particle trap (51) with the outer tube (2) is connected. 10. Gas-insulated plant (1) according to claim 9, wherein the

Particle trap (52) is connected to the inner conductor (3).

11. Gas-insulated plant (1) according to claim 9, wherein the inner conductor (3) is hollow and the particle trap

(52) is connected to the inner conductor (3), so that the field strength weak area (6) is at least partially bounded by the inner conductor (3). 12. Gas-insulated plant (1) according to one of claims 8 to 11, wherein the plant comprises a gas-insulated electrical tion or a gas-insulated electrical switchgear is.

High-voltage direct-current transmission system (35) with egg ^¬ nem converter (36) for transmitting electrical power, the AC side is connected to an AC voltage ^¬ network (37) and the DC side with a DC ^¬ voltage line (381),

characterized in that at least a part of the DC voltage line (381) is a gas-insulated line (1) according to claim 12.