EP3579253B1 - Chain assembly for a high or very high voltage overhead electric line - Google Patents

Description

technical field

The invention relates to a chain arrangement for a high or extra-high voltage overhead line, comprising a long-rod insulator with an insulating core made of fiber-reinforced plastic and at least one end fitting and an arrangement for dissipating surge voltages with at least one protective fitting. The at least one protective fitting is attached to the at least one end fitting of the long-rod insulator.

State of the art

So-called long-rod insulators are used in particular to support the conductors of overhead lines. On the one hand, they create a mechanical connection between the respective overhead line mast and the respective conductor cable. On the other hand, they insulate the conductor cable electrically from the overhead line pylon. Long-rod insulators usually have a circular-cylindrical insulating core that is mechanically connected to end fittings at both ends. As a rule, the insulating core is surrounded by a sheathing that has a shielded outer shape, resulting in a long creepage path along the outside of the insulator. The umbrellas are also usually designed in such a way that the underside of the umbrellas remains as dry as possible when it rains.

The long-rod insulators have a certain specified length, which results from the desired electrical properties, e.g. B. in relation to the possibility of rollover results. The distance between the lower edge of the grounded mast-side part at the top and the live rope-side part at the bottom is relevant here.

Long rod insulators are each part of a chain arrangement. In addition to the insulator, this includes in particular mast-side fastening elements, a carrier device for the conductor cable and, if necessary, a connecting element for a weight unit. The elements of the chain assembly are connected to each other by suitable connecting elements, such as those conforming to international standards such as IEC 60471/19L.

Chain arrangements for high-voltage lines (typically with voltages in the 50-150 kV range) or extra-high-voltage lines (typically with voltages in the 220-400 kV range) are also often equipped with so-called protective fittings. These form, for example, a defined spark gap for dissipating overvoltages, such as those that occur in particular when lightning strikes. This largely prevents the dissipation from taking place via the insulator. Furthermore, an arc between the mast and the cable should be kept away from the insulating core and its possible sheathing and extinguished by an appropriate geometry and materialization of the protective fitting.

Protective fittings often comprise two similarly or identically designed parts, which are fitted above the actual insulator (i.e. on the pylon side) and below the actual insulator (i.e. on the rope side). Fastening by means of separate elements that are fastened above and below the long-rod insulator is typical. These separate elements have some axial extent and thus add to the overall length of the chain assembly.

Traditionally, long-rod insulators were made of ceramic materials. Long-rod insulators with a core made of fiber-reinforced plastic, e.g. B. glass fiber reinforced plastic (GFI<), in importance. In contrast to a ceramic core, the insulating core of such insulators is not cemented into the corresponding end fitting, but is typically clamped or pressed. Due to the greater axial extent of the press or clamp connection compared to the adhesive connection, this usually means that the overall length of a long-rod insulator with a core made of fiber-reinforced plastic is greater than the overall length of an I<eramil< long-rod insulator with corresponding electrical properties .

In particular when retrofitting existing overhead lines with new insulators, the problem arises that the distance between the attachment point on the mast and the conductor cable increases. This is often not permissible or at least not desired, because it means that the conductor cables will hang lower after retrofitting, which can result in higher field strengths of non-ionizing radiation in the ground area below.

A greater length is also disadvantageous because it is associated with a greater pivoting range, and thus with a reduction in the minimum distance between the conductor cable and the mast shaft.

I<ette arrangements are known in which there are no separate elements above and below the long-rod insulator for attaching the protective fittings.

This is how it shows EP 0 038 475 A2 (Arl Pfisterer Elektrotechnische Spezialartil GmbH & Co. KG ) an end fitting for an insulator with a core made of glass fiber reinforced plastic (GFI<). This includes a clamping device with a first clamp and a cone clamp, the clamping sleeve of the cone clamp and the first clamp being supported on one another. The housing of the end fitting, the bracing element, serves as a support for a shielding ring, which is formed by a thickened edge of a funnel. The shielding ring is integrally connected to the housing in the direction of the opposite end fitting.

The DE 30 14 600 A1 (I<arl Pfisterer Elektrotechnische Spezialartil<el GmbH & Co. KG ) relates to a connection fitting for an insulator rod made of glass fiber reinforced plastic with a clamping device matched to the outer diameter of the rod. At a certain length, the fitting should enable a significantly higher holding force than previously known fittings. An additional clamping device is used for this purpose, which is designed for a smaller outside diameter of the bar than the usual clamping device. The clamping elements are preferably made up of at least two clamping cones, which have a weakened zone, e.g. B. an annular groove are connected to each other. The end section of the insulator rod is reduced to the inner diameter of the corresponding clamping cone. A guard ring is formed by the reinforced rim of a bell, the bell being clamped onto the cup-like portion of the end fitting via a hollow cylindrical hub portion slotted longitudinally.

The GB834,085 describes an insulator for high voltage lines with which a line can be fixed to a pole and which has arcing horns.

With these chain arrangements, it can happen that an overvoltage is discharged at least partially in the area that is directly adjacent to the insulating core. This can result in damage to the insulator core, requiring insulator replacement.

Presentation of the invention

The object of the invention is therefore to create a chain arrangement belonging to the technical field mentioned at the outset, which has a reduced susceptibility to faults in the event of overvoltages, while fulfilling the electrical requirements and having a minimum length.

The solution to the problem is defined by the features of claim 1. According to the invention, the at least one protective fitting is fastened in an end-side axial area of the at least one end fitting, outside of a connection area between the insulating core and the end fitting.

Outside the connection area between the insulating core and the end fitting means that there is a first axial area (dissipation area), which is defined by the conductive connection between the protective fitting and the end fitting, and a second axial area (core area), which is defined by the expansion of the insulating core into the end fitting is determined, do not intersect axially. There may be a gap between the areas or they may be immediately adjacent to each other.

The fiber-reinforced plastic is, in particular, glass fiber-reinforced plastic (GFI<). But there are also insulation from other fiber-reinforced plastics such. B. carbon fiber reinforced plastic (CFI <) can be used.

In particular, the long-rod insulator comprises two end fittings, one being arranged at each end of the insulating core. In particular, the chain arrangement also includes two protective fittings, one being attached to each end fitting.

The protective fitting is in particular made of galvanized steel, but designs made of other metallic materials or another material with sufficient conductivity and mechanical stability are also possible. The protective fitting can also be composed of parts made of different materials.

The chain assembly may further include a jacket surrounding the insulating core as described above.

Fastening the protective fitting or protective fittings directly to the end fitting or end fittings enables the chain arrangement to be shortened compared to a chain arrangement in which separate elements are arranged on the long-rod insulator above and/or below. At the same time, the risk is reduced by fastening outside the connection area between the insulating core and the end fitting damage to the insulating core is significantly reduced compared to arrangements in which the fastening takes place in the connection area.

The protective fitting comprises a fastening element which can be attached to the end fitting. This allows attachment to commercially available long rod insulators. For this purpose, the geometry of the fastening element is specifically adapted to the external geometry of the corresponding end fittings, and/or it can be adapted to the external geometry of the end fittings within a certain range. This has the advantage that available long-rod insulators can easily be equipped with protective fittings. Furthermore, the protective fittings attached by means of the fastening element can be easily replaced, e.g. B. after an arcing event.

The fastening element can be formed in one piece with the actual protective fitting, but it can also be present as a separate element which is connected to the actual protective fitting in a suitable manner, e.g. B. welded and / or screwed. The fastening element can be designed in one or more parts. The fastening element preferably comprises a receptacle in which a region of the end fitting can be accommodated with a suitable fit. This enables a mechanically stable fastening of the protective fitting with a large electrical contact area between the fastening element and the end fitting. The receptacle is preferably designed in such a way that the received area lies completely outside the connection area between the insulating core and the end fitting. Correct positioning is advantageously ensured by an appropriate choice of geometry and/or markings on the fastening element and/or the end fitting. For example, the receptacle can include an area that tapers at the end, which interacts with a taper of the end fitting. A stop is also possible, which interacts with the front free end of the end fitting.

In a preferred embodiment, the receptacle is formed by two half-shells. Such a geometry enables simple and secure attachment to the end fitting. The half-shells allow a large-scale attachment with simultaneous Adaptability to slightly different geometries, e.g. B. due to thermal effects or manufacturing tolerances. For this purpose, in particular the mutual distance between the two half-shells is changed slightly. Such a design also guarantees the coaxial alignment between the protective fitting and the insulating core, regardless of the position of the insulating core, particularly when it is deflected.

A symmetrical arrangement of two half-shells, which largely surround the end fitting (preferably at least 70% of the circumference) ensures that currents that arise when dissipating overvoltages and short circuits are diverted axially downwards as far as possible from the half-shells via the outer areas of the housing of the end fitting become. Radial currents through the interior of the end fitting, which could damage the insulating core, are minimized.

Instead of two half-shells, other recordings are also possible, e.g. B. with a rigid cage.

According to the invention, the at least one end fitting has a first through-opening, and the fastening element comprises a second through-opening, so that a bolt-like element is guided through the first and second through-openings to connect the fastening element to the end fitting. This results in a secure mechanical fastening of the protective fitting, the axial position of the fastening element relative to the end fitting also being clearly specified by the clear mutual positioning of the passage openings. Depending on the geometry of the end fitting and the fastening element, fastening by means of bolts allows one or two rotational positions of the fastening element and thus of the end fitting.

In particular, bolts, screws, threaded rods, etc. come into consideration as bolt-like elements. The bolt-like element preferably has a head, which is supported on a first side on the fastening element and/or the end fitting, and a counterpart, which is supported on a second side on the fastening element and/or the end fitting.

The bolt also serves to connect the end fitting to the following element (e.g. a holding device for the conductor cable) together. In addition to its mechanical function, the bolt has the task of creating a reliable electrical connection between the protective fitting and the subsequent element. High currents can thus be discharged largely independently of the end fitting.

The combination of a fastening element with two half-shells and the connection with the bolt-like element is particularly preferred. The head of the bolt-like element is located outside a first of the half-shells. The element passes through this first half-shell, then the end fitting and finally the second half-shell in the corresponding through-openings. On the outside of the second half-shell, the bolt-like element then has a counterpart, which secures the element together with the head against slipping out.

The protective fitting is in particular a protective ring. Such protective rings ensure that no corona discharges occur in the interior of the ring, which could damage the long-rod insulator. Analogously to a Faraday cage, they shield the interior space defined by the protective ring or protective rings. This avoids peak discharges on elements of the long-rod insulator.

The protective ring does not necessarily have to be a closed ring. The ring can be interrupted and have two free ends, in particular for the defined discharge of overvoltages between two correspondingly designed protective rings. When the protective ring is fastened by means of a fastening element with two half-shells, the protective ring preferably comprises a ring element which is connected to each of the half-shells via an arm in each case. This results in a mechanically stable attachment and a defined and even discharge of overvoltages from the ring element via the arms and the fastening element into the end fitting and the subsequent element.

The invention can also be implemented with other protective fittings, e.g. B. with protective horns or protective bells. The protective fittings can each be attached one or more times at both ends or only on one side - depending on the protective function and needs.

In particular, a press connection is formed between the insulating core and the end fitting in the connection area. Such connections have proven to be well suited for insulating tubes made of fiber-reinforced plastic.

The invention can also be implemented with long-rod insulators in which the insulating core is connected to the end fitting in a different way, e.g. B. via an adhesive connection or a screw connection.

Advantageously, the chain arrangement comprises two protective fittings of the same design, each of which is fastened to one of two end fittings. The use of protective fittings of the same design results in reduced storage costs because different components do not have to be kept on hand for both sides.

Further advantageous embodiments and combinations of features of the invention result from the following detailed description and the entirety of the patent claims.

Brief description of the drawings

Fig. 1A, B

Zwei Seitenansichten einer installierten erfindungsgemässen Kettenanordnung;

Fig. 2A, B

zwei Seitenansichten des Schutzrings der Kettenanordnung;

Fig. 2C

eine Draufsicht auf den Schutzring; und

Fig. 3

einen vertikalen Querschnitt durch einen Endbereich des Isolators und das Befestigungselement des Schutzrings.

The drawings used to explain the embodiment show:

Fig. 1A,B

Two side views of an installed chain assembly according to the invention;

Figure 2A,B

two side views of the protection ring of the chain assembly;

Figure 2C

a plan view of the guard ring; and

3

a vertical cross-section through an end portion of the insulator and the attachment element of the guard ring.

In principle, the same parts are provided with the same reference symbols in the figures.

Ways to carry out the invention

The Figures 1A, 1B show two side views of an installed chain arrangement 100 according to the invention. The arrangement shown is designed for an operating voltage of 145 kV.

The chain arrangement 100 includes a long-rod insulator 110 with a glass fiber insulating core. The insulator is below, in connection with the figure 3 described in more detail. The chain arrangement 100 further comprises two protective rings 150 which are attached to the upper and lower ends of the long-rod insulator 110 in a mirror-inverted manner. They will be discussed below, in connection with the figure 2 described in more detail.

The chain assembly 100 is suspended from an overhead power line pylon (not shown) by a steel hanger 10 known per se. At the lower end of the chain arrangement 100, namely at the lower end fitting 130 of the long-rod insulator 110, a double strap 20 made of steel is attached. In this a suspension clamp 30 made of aluminum and steel is added, which carries the conductor cable 1 of the overhead line. A protective spiral 35 made of aluminum is arranged between the suspension clamp 30 and the conductor cable 1 in a manner known per se. At the lower end of the double link 20 a fork link 40 made of steel is attached, which carries a weight unit 50 .

The minimum breaking load of the entire chain arrangement is 120 kN. The fork connection dimensions correspond to the standard IEC 60471/19L. The steel parts are each hot-dip galvanized.

In the exemplary embodiment shown, the length a of the chain arrangement (measured from the upper connection axis to the hanging device to the lower connection axis to the double strap) is 1504 mm. The length b between the suspension device and the cable suspension point is 1700 mm.

The Figures 2A, 2B show two side views of the protection ring of the chain assembly, the Figure 2C shows a plan view of the guard ring. The guard ring 150 is made of steel. It comprises the actual ring 152, the fastening element 160 and two arms 154, 156 connecting the ring 152 and the fastening element 160, which are welded at their ends to the ring 152 and to the fastening element 160, respectively. The ring 152 is not closed in itself, but ends in two end horns 152a, 152b, which are bent at an angle of 10° to the ring main part and which each have a spherical end part at their end.

The two guard rings 150 of the chain assembly 100 are arranged such that the spherical end portions face away from each other. A defined path for discharging overvoltages is formed, which extends from the terminating parts of the end horns 152a, 152b on one side of the long-rod insulator 110 to the terminating parts of the end horns 152a, 152b on the other side of the long-rod insulator 110. The two protective rings 150 electrically shield the main part of the long-rod insulator 110 . The result is a lightning withstand voltage of 660 kV.

The fastening element 160 comprises two half-shells 162, 164. They each have a U-shaped cross section and are arranged in mirror images facing one another, so that they define a receiving space between them. A bolt 170 made of steel runs through aligned through-openings in the two half-shells 162, 164.

The arms 154, 156 extend from the ring 152 initially perpendicular to the plane defined by the ring body. After a straight section, they follow a 90° arc and are welded to one of the half-shells 162, 164 at their end opposite the ring 152.

The figure 3 Fig. 12 shows a vertical cross-section through an end portion of the insulator and the guard ring attachment member, taken along line AA in Fig Figure 2C .

The long-rod insulator 110 includes an insulating core 120 made of high-strength glass fiber reinforced plastic, which is surrounded by the end fitting 130 at its end. The insulating core 120 is in its central area, which extends over approx. 90% of the length of the insulator, surrounded by a shielded jacket 132 of silicone material. The screens result in a creepage distance of 3,870 mm.

While the insulating core 120 is held in the end fitting 130 via a press connection, there is an adhesive connection between the insulating core 120 and the casing 132 in the end regions of the casing 132 .

The rod which forms the ring 152 of the protective ring is located in the cross section shown to the side of the end fitting 130, approximately at the level of the outer end of the casing 132.

The fastening element 160 with the two half-shells 162, 164 encloses a fork-like end section of the end fitting 130. It does not extend into the connection area between the end fitting and the insulating core (cf. the dashed line). Both the fastening element 160 and a connecting part of the double link 20 are fastened to the end fitting 130 by means of a bolt 170 . The bolt 170 has a bolt head 172 and, on the opposite side, a snap-on retaining ring 174 so that it is secured against slipping out of the end fitting 130 .

The bolt 170 not only serves to mechanically fasten the fastening element 160 to the end fitting 130, it also ensures the correct axial positioning and rotational position of the protective fitting 150 relative to the long-rod insulator 110. It also conducts a significant proportion of the leakage current from the fastening element 160 to the connecting part of the double strap 20.

To fasten the protective ring 150 to the end fitting 130 of the long-rod insulator 110, the fastening element 160 with the two half-shells 162, 164 is pushed axially onto the end section of the end fitting 130 from the outside. Then the connecting part of the double strap 20 is pushed into the fork-like end section of the end fitting 130 . Finally, the bolt 170 is pushed in and secured.

The discharge of currents resulting from overvoltages and short-circuits occurs from the ring 152 of the protection ring 150 through the arms 154, 156, the half-shells 162, 164 and the bolt 170 to the double bracket 20 and from there to the suspension clamp 30. With this dimensioning, currents of 2 x 20 kA can be transmitted per half-shell and bolt part.

When retrofitting an existing long-rod insulator, the existing bolt is removed and replaced by a longer model so that the two half-shells can also be accommodated between the bolt head and the opposite retaining ring.

Within the scope of the chain arrangement according to the invention, spacers for attaching protective fittings between the long-rod insulator and the respective fastening part (hanging device or double strap with hanging clamp) can be saved. For example, there is a length reduction of 120 mm for each intermediate piece saved, which means 240 mm for protective fittings arranged on both sides. Typical I<ette arrangements with long-rod insulators with a GRP core are approx. 220 mm longer than corresponding arrangements with I<eramil<insulators. This additional length can thus be compensated in the case of attachment on both sides according to the solution according to the invention. There is even a certain reduction in the overall length.

The invention is not limited to the illustrated embodiment. In particular, other types of protective fittings can also be attached to the end fitting in the manner according to the invention. If necessary, only one protective fitting is present. The geometry of the fastening part can differ from that of the exemplary embodiment. The half-shells can be shaped differently, or instead of half-shells, a one-piece receptacle is used, which optionally includes flexible sections. The fastening part can be fixed to the end fitting by another element instead of the bolt or in addition to the bolt, e.g. B. a clamping mechanism. In this case, the positioning can be ensured by other means, in particular stop means.

The long-rod insulator shown is only to be understood as an example. With a different geometry of the end fitting and/or a different expansion of the Isolating core in the end fitting also results in a different geometry of the fastening part.

In summary, it can be stated that the invention creates a chain arrangement which has a reduced susceptibility to faults in the event of overvoltages, while meeting the electrical requirements and having a minimum length.

Claims (7)

1. Chain assembly (100) for a high or very high voltage overhead electric line, comprising

   a) a long rod-type insulator (110) having an insulating core (120) composed of fibre-reinforced plastic and having at least one end fitting (130),

   b) an assembly for surge arresting having at least one protective fitting, wherein

   c) the at least one protective fitting comprises a fastening element (160) which is fastened to the at least one end fitting (130) of the long rod-type insulator (110),

   d) wherein the at least one protective fitting is fastened in an end-side axial region of the at least one end fitting (130), outside a connecting region between the insulating core (120) and end fitting (130),

   e) the at least one end fitting (130) has a first passage opening, and in that the fastening element (160) comprises a second passage opening, and therefore, in order to connect the fastening element (160) to the end fitting (130), a bolt-like element (170) is guided through the first and the second passage opening,

   characterized in that the bolt-like element (170) also serves for connecting the end fitting (130) to a following element, in particular to a holding device for a conductor cable (1).
2. Chain assembly (100) according to Claim 1, characterized in that the fastening element (160) comprises a receptacle in which a region of the end fitting (130) can be accommodated so as to fit therein.
3. Chain assembly (100) according to Claim 2, characterized in that the receptacle is formed by two half shells (162, 164).
4. Chain assembly (100) according to one of Claims 1 to 3, characterized in that the protective fitting is a protective ring (150).
5. Chain assembly (100) according to Claim 3 and according to Claim 4, characterized in that the protective ring (150) comprises a ring element (152), the ring element (152) being connected to each of the half shells (162, 164) via a respective arm (154, 156).
6. Chain assembly (100) according to one of Claims 1 to 5, characterized in that a press connection between the insulating core (120) and end fitting (130) is formed in the connecting region.
7. Chain assembly (100) according to one of Claims 1 to 6, characterized in that it comprises two identically designed protective fittings which are fastened to one of two end fittings (130) each.

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