Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
  • H02B1/00—Frameworks, boards, panels, desks, casings; Details of substations or switching arrangements
  • H02B1/16—Earthing arrangements

Definitions

• the invention refers to an arrangement for disconnectable leading out and earthing of a metallic shield of a cable, arranged at the end of a cable section and made with an earthing terminal connected with first and second shield parts of phase conductors surrounded by respective sheaths made of a highly conductive material, especially metal.
• This a angement is applicable for disconnectable leading out and earthing of cable shields and sheaths at the ends of high voltage and high capacity three-phase cable lines and anywhere in the route of such cable lines.
• the mounting step depicted here is also necessary for neutralizing the negative influence of the atmospheric discharges.
• the cable lines are generally prepared from sections of equal lengths, but this is only a preferred solution which may not be followed if necessary.
• the conductive shields of the cables connected in this way ensure leakage current lines for the sheath currents flowing in the sheaths of the phase conductors and equipotential conditions in the conductive shields of a cable. This is necessary especially because of the presence of electric fields generated by the high strength currents flowing in the middle and high capacity cable lines.
• the high strength currents induce high voltage in the shields and sheaths made of highly conductive materials, especially metals, and the high voltage results in increased temperature of the whole cable and in decreased loadability thereof, i.e. the high voltage causes increased losses in the power transmission. Another negative consequence of the increased temperature can be seen in shortening of the life-time of the cable and of the plastic parts thereof.
• the present invention is based on the recognition that the arrangement for disconnectable leading out and earthing of the conductive metallic shields of cables should be prepared and equipped with a closed, in given case pressure-tight vessel, which contains sealed introducing tube-type elements and earthing clamps.
• the vessel is prepared for receiving a leakage conductor connected with the conductive shield parts of phase conductors of a cable section, the phase conductors wherein the high strength current flows are not introduced into the vessel, they are laid down separately.
• This construction is advantageous because of increasing the reliability of the cable line, of ensuring the possibility of very simple pressure control, and the measurement of the inner pressure gives information whether the failure of the cable line followed at the arrangement or not - when water is present in the vessel the inner pressure decreases.
• the object of the present invention is to prepare an arrangement of high electric strength sealed against entering water, wherein the arrangement arranged at the connecting points of cable line section renders it possible to realize sections necessary for cross-bonding the sheaths and shields and in cable lines prepared with continuous cross-bonded sheaths improves the reliability of earthing of the cable sections in comparison to the known solutions.
• the object of the invention is an arrangement for disconnectable leading out and earthing of a metallic shield of a cable, arranged at the end of a cable section and made with an earthing terminal connected with first and second shield parts of phase conductors surrounded by respective sheaths made of a highly conductive material, especially metal.
• the essence of the invention is that it is made with a vessel equipped with introducing elements for receiving the first and second shield parts and the sheaths, further respective first and second connecting terminals arranged in different distances from the introducing elements, and an earthing bar connected with the first and second connecting terminals, wherein the earthing terminal is joined with the earthing bar.
• the sealing of the arrangement of the invention against water is especially highly reliable in the advantageous embodiment wherein the vessel is made in the form of a pressure-tight housing, wherein the earthing terminal is fixed on the wall of the pressure-tight housing.
• the introducing elements of the vessel made in the form of a pressure-tight housing are equipped with packing glands surrounding in a pressure-tight way the first and second shield parts of the respective phase conductors.
• the packing glands forming the parts of the introducing elements are capable of sealed fixation and holding of the sheath surrounding the first and second shield parts, hence, water cannot enter the inner space of the pressure-tight housing through the introducing elements.
• the vessel made in the form of a pressure-tight housing includes clamping units constituting first and second connecting terminals for fixing the first and the second shield parts of each of the phase conductors, respectively, and the clamping units are arranged on a holding wall and joined by respective electrically conducting passage conductors.
• the clamping units are connected through respective bars with the earthing bar or constitute a part of the earthing bar, advantageously the clamping units are prepared as a part of the earthing bar.
• the measurements of the inner pressure can be carried out in a very simple manner in that advantageous embodiment wherein the pressure-tight housing comprises a valve arranged in its outer wall.
• the handling is simplified in that advantageous embodiment of the arrangement of the invention wherein the pressure-tight housing consists of two outer parts made of stainless steel, the outer parts having respective flanges and connected oblong the flanges through a sealing insert.
• the arrangement of the invention constitutes a unit of very long life-time, high reliability and facilitates the fault location in a cable line. It can be simply arranged in the cable line and if necessary filled up with air or protective gas.
• Fig. 1. is the top view of the arrangement of the invention
• Fig. 2. is a side-view cross-section of the arrangement of the invention
• Fig. 3. represents the simplified link diagram realized with the electric parts of a cable in the arrangement of the invention.
• the arrangement of the invention is generally applied in high voltage and high capacity cable lines especially in cross-bonded cable systems.
• the phase conductor of a cable line is equipped with a sheath 2 which is arranged in a packing gland 1 ensuring hermetic sealing around it. Under the sheath 2 the phase conductors are disconnected from first and second shield parts 14 and 15 made of metal, the phase conductors remaining conducted outside of the arrangement.
• the first and second shield parts 14 and 15 can be united with inner conductors of the arrangement of the invention as described later.
• the packing gland 1 is arranged in the outer wall of a vessel which is preferably a pressure-tight housing 7 made advantageously of stainless steel.
• a respective first connecting terminal 3 and a second connecting terminal 4 are prepared wherein the first connecting terminals 3 receive the first shield parts 14 and the second connecting terminals 4 receive the second shield parts 15 of the sheaths 2.
• the first and second connecting terminals 3 and 4 are connected also with the respective inner conductors in the manner that the first connecting terminals 3 belonging to different phase conductors are connected with respective one of the second connecting terminals 4 by respective passage conductors 13.
• the second connecting terminals 4 are preferably fixed on a holding plate 11 built-in into or constituting a part of the pressure-tight housing 7 and similarly, the first connecting terminals 3 are arranged on an earthing bar 6.
• the earthing bar 6 is connected to an earthing terminal 5 through a leakage conductor 12.
• the earthing terminal 5 crosses the outer wall of the pressure-tight housing 7 and can be connected to an earthing unit through a leakage conductor (Figs 1 and 2) not marked in the figures.
• a leakage conductor Figs 1 and 2
• a valve 9 In the outer wall of the pressure-tight housing 7 it is preferred to arrange a valve 9 whereby a passage-way for pressurizing the inner space of the pressure-tight housing 7 and/or for measuring the inner pressure is ensured.
• the pressure-tight housing 7 is preferably made of two halves generally of different shapes and advantageously of a lower half shown in Fig. 1 and a cover forming an upper part not shown in the drawings.
• the lower part and similarly the cover are limited by respective flanges 16 having plane surface and in this surface a riffle 17 is prepared for receiving a sealing insert 8 made of a flexible material.
• the lower half and the cover can be united and pressed to one another by screws or other fixing elements and the pressure-tight housing 7 prepared in this way can be reliably sealed according to the known principles.
• the inner space of the pressure-tight housing can be filled up also with air or other appropriate gas through the valve 9.
• the pressure-tight character of the housing can be ensured in another way, too, neither the use of the valve 9 nor the application of the sealing insert 8 is necessary, the construction can be manufactured in any other known manner applicable in the manufacture of the pressurizable vessels.
• Both halves of the pressure-tight housing 7, as mentioned, are made preferably of stainless steel, the holding plate 11 is aimed to give fixation the parts carrying the first and second connecting terminals 3 and 4.
• Fig. 3 a schematic electric link diagram of the arrangement of the invention is shown. It is clear from this figure that the first and second shield parts 14 and 15 are connected with an earthing unit through the first and second connecting terminals 3, 4 and in this way it is ensured that the first and second shield parts 14 and 15 form equipotential electric conducting elements of the cable line, i.e. no potential difference can be measured between them.
• the pressure-tight housing 7 If it is desired it can be preferred to fill up the pressure-tight housing 7 with an insulating material up to the level of the first and second connecting terminals 3 and 4 and this insulating material gives protection of the electric equipment within the pressure-tight housing 7 against water which incidentally can enter the inner space thereof. Thereby also the process of a penetrating the cable by water is delayd from the pressure-tight housing 7.
• the arrangement of the invention is aimed to replace the very simple solutions applied up to date. It offers savings in work, i.e. it can be applied easier than the known arrangements in the cross-bonded cable systems.
• the arrangement of the invention is applicable for disconnectable leading out and earthing the conductive cable sheaths and metallic shield parts at the ends of the sections of a high voltage and high capacity cable line. It is especially suitable for preparing sections of a long distance cross-bonded cable line and can be applied also in continuous cable lines.
• the access to the arrangement is provided during sheath test and sheath fault location. The arrangement offers remarkable savings in costs of operating a cable line because of facilitating the maintenance.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Cable Accessories (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10982413

Family Applications (1)

Country Status (4)

Cited By (1)

Citations (2)

Family Cites Families (2)

• 1992
  • 1992-10-09 HU HU9203202A patent/HU215221B/hu not_active IP Right Cessation
• 1993
  • 1993-09-29 AU AU51180/93A patent/AU5118093A/en not_active Abandoned
  • 1993-09-29 DE DE4395187T patent/DE4395187T1/de active Pending
  • 1993-09-29 DE DE4395187A patent/DE4395187C2/de not_active Expired - Fee Related
  • 1993-09-29 WO PCT/HU1993/000055 patent/WO1994009541A1/en active Application Filing

Patent Citations (2)

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