EP2095376A1 - Matériau de transformation de champ - Google Patents

Matériau de transformation de champ

Info

Publication number
EP2095376A1
EP2095376A1 EP07852215A EP07852215A EP2095376A1 EP 2095376 A1 EP2095376 A1 EP 2095376A1 EP 07852215 A EP07852215 A EP 07852215A EP 07852215 A EP07852215 A EP 07852215A EP 2095376 A1 EP2095376 A1 EP 2095376A1
Authority
EP
European Patent Office
Prior art keywords
grading material
field
field grading
material according
zinc oxide
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07852215A
Other languages
German (de)
English (en)
Other versions
EP2095376A4 (fr
Inventor
Erik Jonsson
Tommaso Auletta
Henrik Hillborg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Research Ltd Switzerland
ABB Research Ltd Sweden
Original Assignee
ABB Research Ltd Switzerland
ABB Research Ltd Sweden
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ABB Research Ltd Switzerland, ABB Research Ltd Sweden filed Critical ABB Research Ltd Switzerland
Publication of EP2095376A1 publication Critical patent/EP2095376A1/fr
Publication of EP2095376A4 publication Critical patent/EP2095376A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G15/00—Cable fittings
    • H02G15/02—Cable terminations
    • H02G15/06—Cable terminating boxes, frames or other structures
    • H02G15/064—Cable terminating boxes, frames or other structures with devices for relieving electrical stress
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G15/00—Cable fittings
    • H02G15/08—Cable junctions
    • H02G15/10—Cable junctions protected by boxes, e.g. by distribution, connection or junction boxes
    • H02G15/103—Cable junctions protected by boxes, e.g. by distribution, connection or junction boxes with devices for relieving electrical stress
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G15/00—Cable fittings
    • H02G15/08—Cable junctions
    • H02G15/18—Cable junctions protected by sleeves, e.g. for communication cable
    • H02G15/184—Cable junctions protected by sleeves, e.g. for communication cable with devices for relieving electrical stress

Definitions

  • the present invention relates to a field grading material comprising a polymeric matrix and filler particles, as well as to a device for grading an electric field.
  • the invention also relates to use of a field grading material at a joint or termination of an electric power cable.
  • a cable comprises an insulating layer arranged around the conductor and a grounded shield arranged around the insulating layer.
  • the grounded shield in the cable could also be referred to as a grounded outer conducting layer.
  • the electric field is uniform along the cable axis and there is a variation in the field only in the radial direction. The entire potential difference between the conductor and the shield occurs across the insulation.
  • medium voltage refers to a voltage in the interval 1-36 kV and high voltage to a voltage greater than 36 kV.
  • the electric stresses in question can be reduced by grading the electric field at the transition of the electric field from the first medium to the second medium, e.g. from a shielded cable part to a cable part where the original shield has been removed.
  • grading the electric field at the transition of the electric field from the first medium to the second medium, e.g. from a shielded cable part to a cable part where the original shield has been removed.
  • There are a number of known methods for providing a stress control for example, by means of geometrical field control in the form of a stress cone arranged at the position where the shield ends, or to have a material that has the ability to distribute the field by itself.
  • the material is usually referred to as a field grading material, but is also called a stress grading material.
  • the electrical properties of a field grading material are dependant on the field it is exposed to. In connection with a field grading material both capacitive and resistive field grading are mentioned.
  • Capacitive field grading is used in alternating current applications. Capacitive field grading can also be used to achieve field grading when voltages are occurring in the form of impulses.
  • a body of a material having a dielectric constant higher than that of the insulation and with as low losses as possible is introduced around the unshielded part of the cable in the area closest to the shielded part of the cable and in electrical contact with the shield, whereby the spreading of the equipotential lines will be achieved.
  • Capacitive field grading properties are also desired in a material adapted for grading the electric field in high- voltage direct current (HVDC) applications so as to achieve an effective field grading in case of suddenly occurring voltage surges .
  • HVDC high- voltage direct current
  • Resistive field grading can be used in alternating current as well as direct current applications. Resistive field grading can also be used in order to achieve field grading when voltages are occurring in the form of impulses.
  • a body having a suitable resistance is introduced around the unshielded part of the cable in the area closest to the shielded part and in electric contact with the shield.
  • a resistive voltage drop then occurs in the body, which results in a more uniform distribution of the potential. This potential distribution will be more linear if the body consists of a material exhibiting a non-linear electrical resistance that decreases with an increasing electric field.
  • the non-linearity starts in a specific region of the electric field.
  • the voltage drop along the field grading body will become more uniformly distributed in a body that exhibits such a nonlinear electrical resistance than in a body that does not.
  • a field grading material with a non-linear electrical resistance i.e. a material that does not follow Ohms law, is achieved by combining at least two materials to a composite. Due to the area of use, the field grading material should be mechanically flexible. It is therefore suitable to use, for example, a rubber as a matrix and to mix it with semiconducting particles that is non-conducting at low voltages but becomes conducting at higher voltages. The particles forms a network within the matrix and the result is a composite being insulating at low electrical fields and having increased conductivity at higher electrical fields.
  • a polymeric matrix containing nanoparticles of zinc oxide (ZnO) or silicon carbide (SiC) is described in published patent document WO2004/038735, where the polymeric matrix at least essentially consists of rubber, thermoplastics or a thermoplastic elastomer.
  • European patent document EP 0 088 450 Bl describes a field grading material comprising a polymeric matrix comprising particles of ZnO or SiC, and carbon black particles.
  • WO 2005/036563 describes a field grading material with a polymeric matrix comprising a nanoparticle filler heterogeneously distributed in the matrix.
  • the nanoparticle filler may be ZnO particles.
  • the surface of the nanoparticle may be modified by treatment with an anorganosilane or organotitanante compound.
  • An object of the invention is to provide a field grading material of the type indicated in the preamble of claim 1 having improved or similar properties with respect to field grading materials already known. According to a first aspect of the invention this object is obtained by a field grading material according to claim 1.
  • the field grading material comprises a polymeric matrix and a filler comprising zinc oxide and carbon black.
  • the zinc oxide is essentially in the form of pure zinc oxide particles having at least one dimension smaller than, or equal to, 100 nm.
  • the combination of pure zinc oxide particles smaller than, or equal to, 100 nm and carbon black in a polymeric matrix gives a field grading material with excellent field grading properties.
  • Excellent field grading properties refers to a material having the desired non-linear properties, as described under "background art", for the field grading material.
  • the field grading material is cost effective to produce, because pretreatment of the zinc oxide particle by surface treatment or by addition of doping substances is not necessary.
  • pure zinc oxide refers to zinc oxide where the properties of the pure zinc oxide has not been modified by, for example, surface treatment or by addition of, for example, doping substances.
  • pure zinc oxide does not exclude zinc oxide that contains a small amount of other substances than zinc oxide, for example, that is naturally present in the zinc oxide or origin from a contamination during the manufacturing of the zinc oxide .
  • nano-sized particles having at least one dimension smaller than or equal to 100 nm refers to nano-sized particles having a width, length and/or height smaller than or equal to 100 nm.
  • the nano-sized particles may of course have several or all dimensions smaller than or equal to 100 nm.
  • the nano-sized particles may have any shape as long as they in at least one of their dimensions are in the interval of 0.1-100 nm.
  • the pure zinc oxide particles have at least one dimension in the interval of 20-70 nm.
  • the pure zinc oxide particles constitute less than 40% by volume of the field grading material.
  • the pure zinc oxide particles constitute less than 30% by volume of the field grading material.
  • the carbon black has an average particle size in the interval 1-100 nm, preferably 10-60 nm, and most preferably 15-50 nm.
  • the carbon black constitutes between 0.2-10 % by volume, preferably 0.5-4 % by volume, and most preferably 1-3% by volume of the field grading material.
  • the carbon black is self-assembling and is adapted to form a percolated network structure of carbon black and ZnO in the polymeric matrix.
  • the electrical resistance of the material changes from a linear to a non-linear behavior.
  • the amount of carbon black is chosen in dependence on the desired resistivity of the material.
  • the self-assembling carbon back makes it possible to use very small amounts of carbon black to achieve the percolated network.
  • the carbon black is, for example, the commercially available
  • Ketjenblack ® Ketjenblack ® .
  • the carbon black has an average size between 40-500 nm.
  • the carbon black constitutes between 5-40 % by volume, preferably 10-30 % by volume, and most preferably 10-15 % by volume of the field grading material.
  • the carbon black is between 40-500 nm it is present in the form of ball-shaped graphite.
  • the ball- shaped graphite is present in form of filaments in the polymer matrix.
  • the carbon filaments and pure zinc oxide particles turns into conducting paths and give the material its non-linear properties which are desired for grading the electric field.
  • the polymeric matrix comprises EPDM (Ethylene Propylene Diene Monomer) rubber.
  • EPDM has a good dielectric strength and has a low price compared to other polymeric matrix that could be used.
  • the polymeric matrix comprises silicone.
  • the field grading material can be injection molded to an electric field control device. Thereby the time for production of an electric field control device can be shortened. Also it is easier to manufacture a device with a complex shape due to the low viscosity of EPDM.
  • the polymeric matrix comprises EVA (Ethylene Vinyl Acetate) .
  • the object is achieved with an electric field control device for grading an electric field at an interruption of the insulation layer arranged around the conductor in a medium or high voltage cable, wherein the device comprises a field grading material according to any of claims 1-12.
  • An interruption in the insulation of an electric cable occurs for example at a joint or at a termination of a cable.
  • the field grading material in the electric field control device is arranged circumferential around the interruption of the insulation and in contact with the conductor of the cable and with a grounded outer conducting layer of the cable. This provides a uniform distribution of the electric field in a joint or termination for a cable for DC or AC.
  • the object is achieved with the use of a field grading material according to claim 15 or 16.
  • Figure 1 is a diagram showing the electrical resistivity as a function of applied electrical field for a field grading material according to an embodiment of the invention
  • Figure 2 is a schematic cross-section of the field grading material according to an embodiment of the invention.
  • Figure 3 is a schematic longitudinal cross-section of a joint of an electric power cable, provided with a body comprising a field grading material according to the invention. DESCRIPTION OF PREFERRED EMBODIMENTS
  • the field grading material according to the present invention comprises a polymeric matrix and a filler comprising zinc oxide and carbon black.
  • the zinc oxide is in the form of pure zinc oxide particles having at least one dimension smaller than or equal to 100 nm.
  • the electrical resistivity (Ohmm) as function of applied electrical field (kV/mm) for a field-grading material comprising pure ZnO nanoparticles and carbon black is illustrated in figure 1.
  • Curve A represents a field grading material comprising an EPDM matrix with 23 % by volume of pure zinc oxide nanoparticles and 1 % by volume of carbon black. The average diameter of the pure zinc oxide particles is 53 nm.
  • the carbon black is Ketjenblack ® EC 300, with an average particle size of 20-30 nm. Ketjenblack ® EC products are electroconductive carbon black of very high purity.
  • Ketjenblack ® EC-300J Due to their unique morphology in comparison to conventional carbon blacks, substantially lower amounts of Ketjenblack ® EC-300J, and even lesser amounts of Ketjenblack ® EC-600JD, are required for making plastics and elastomers conductive. This results in improved processing and mechanical properties of the finished electroconductive articles.
  • the field grading material was prepared by drying the ZnO particles in vacuum at 190 0 C over night before use. Carbon black and the ZnO nanoparticles were added to the EPDM matrix.
  • the matrix comprises EPDM as well as a stabilizer (stearic acid) and a peroxide curing agent (VAROX) . The compound was carefully mixed using a Brabender internal mixer at a temperature less than 80 0 C.
  • the samples were compression molded at 180 0 C during 30 min.
  • the samples were subsequently degassed in a vacuum-oven during 24 h and 80 0 C to evaporate by-products from the peroxide vulcanization.
  • the final dimensions of the samples were approximately 1 mm in thickness and 210 mm in diameter.
  • Curve A shows that the above described material has a non- linearity which starts between l,0E9 and 1,0ElO ohmm and a conductivity at high electrical fields which makes the material suitable for use as a field grading material.
  • the level of the resistivity of curve A shows that the material is especially suitable to be used as a field grading material for High Voltage Direct Current (HVDC) applications.
  • Figure 1 also shows, as comparison, the electrical resistivity as function of applied electrical field for a material comprising EPDM rubber and 25 vol % pure ZnO particles with an average diameter of 53 nm, curve B. In this case, where no carbon black is added, an insulating material without field grading properties is obtained within the electric field of interest, 0.1-8 kV/ ⁇ n ⁇ n.
  • Figure 2 shows an example of the distribution of pure zinc oxide and the carbon black in the EPDM matrix of the electric field grading material according to curve A in figure 1.
  • the carbon black and pure zinc oxide are distributed in the form of aggregates, or a network, and when the electrical field is sufficiently high for the resistivity to become non-linear the ZnO particles conduct current and the aggregates, or network, forms conducting paths in the polymer matrix.
  • the polymeric matrix of the field grading material according to the present invention suitably consists, or at least essentially consists, of rubber, thermoplastics or a thermoplastic elastomer. It is preferred that the matrix consists, or at least essentially consists, of polyolefin rubber or thermoplastic polyolefin elastomer/plastomer, preferably including EPDM rubber, silicone rubber or EVA (Ethylene Vinyl Acetate) , or of semi-crystalline thermoplastics, preferably polyethylene or cross-linked polyethylene (PEX) .
  • a field grading material according to the invention is particularly suitable for use in an electric field control device for grading an electric field in medium or high voltage applications.
  • Figure 3 schematically shows a cable joint comprising such an electric field control device 7.
  • the cable joint 1 comprises a conductor 2 and cable insulation 3.
  • the cable usually comprises an inner conducting layer (not shown) arranged between the conductor and the insulation, and an outer conducting layer 4 arranged outside and surrounding the insulation.
  • the insulation 3 and conducting layer (s) 4 is cut off for a distance and the two conductor ends is connected with a metallic cable sleeve 5.
  • the sleeve is surrounded by a deflector 6 of conducting rubber.
  • An electric field control device 7 comprising a field grading material according to the invention is arranged over the end of the outer conductive layer 4 to achieve a uniformly distributed electric field in the cable insulation 3. Outside the field grading material there is provided a second insulation layer 8.
  • a semi-conducting layer 9 with a grounded screen 10 that is in contact with the grounded outer conducting layer 4 of the cable is arranged around the field control layer 7 and the second insulation layer 8
  • the field grading material may be used in a cable termination or other electrical equipment where it is suitable to use a field grading material.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Organic Insulating Materials (AREA)

Abstract

L'invention concerne un matériau de transformation de champ comprenant une matrice polymère pourvue d'une charge comprenant un oxyde de zinc et du noir de charbon, l'oxyde de zinc se présente sous une forme de particules d'oxyde de zinc pur possédant moins une dimension plus petite ou égale à 100 nm. L'invention concerne aussi un dispositif de commande de champ électrique (7) destiné à transformer un champ électrique lors d'une interruption de la couche isolante agencée autour du conducteur dans un câble à haute ou à moyenne tension, ce dispositif comprenant le matériau de transformation de champ.
EP07852215A 2006-12-20 2007-12-05 Matériau de transformation de champ Withdrawn EP2095376A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0602789A SE531409C2 (sv) 2006-12-20 2006-12-20 Fältstyrande material
PCT/SE2007/050943 WO2008076058A1 (fr) 2006-12-20 2007-12-05 Matériau de transformation de champ

Publications (2)

Publication Number Publication Date
EP2095376A1 true EP2095376A1 (fr) 2009-09-02
EP2095376A4 EP2095376A4 (fr) 2010-09-15

Family

ID=39536563

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07852215A Withdrawn EP2095376A4 (fr) 2006-12-20 2007-12-05 Matériau de transformation de champ

Country Status (4)

Country Link
EP (1) EP2095376A4 (fr)
CN (1) CN101563734A (fr)
SE (1) SE531409C2 (fr)
WO (1) WO2008076058A1 (fr)

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2197080A1 (fr) * 2008-12-09 2010-06-16 ABB Research Ltd. Joint flexible avec materiau résistive de transformation d'un champ électrique pour câbles à courant continu à haute tension et méthode pour la connexion de ces câbles
EP2276040B1 (fr) 2009-07-15 2017-03-01 ABB Research LTD Dispositif pour connexion électrique, procédé de production d'un tel dispositif, et installation électrique
EP2337070A1 (fr) * 2009-12-17 2011-06-22 ABB Technology AG Dispositif électronique doté d'une évaluation du champ résistif non linéaire et son procédé de fabrication
EP2362407B1 (fr) 2010-02-23 2012-10-03 ABB Research Ltd. Düse für einen Leistungsschalter und Leistungsschalter mit einer solchen Düse
CN102906955B (zh) 2010-05-21 2015-09-23 Abb研究有限公司 高压直流电缆终端装置
CA2799601C (fr) 2010-05-21 2016-07-05 Abb Research Ltd Appareil de terminaison de cable pour courant continu a haute tension
EP2572424B1 (fr) 2010-05-21 2015-03-25 ABB Research Ltd. Terminaison d'un câble haute tension à courant continu
EP2572422A2 (fr) * 2010-05-21 2013-03-27 ABB Research Ltd. Appareil de terminaison de câble pour courant continu à haute tension
AU2012280287B9 (en) * 2011-07-05 2015-07-23 Nkt Hv Cables Ab A device for electric field control
EP2742098A4 (fr) * 2011-09-01 2015-07-08 Rensselaer Polytech Inst Polymère d'oxyde de graphène avec résistivité non linéaire
EP2639264A1 (fr) * 2012-03-14 2013-09-18 Nexans Matériau de calibrage de champs
US9306340B2 (en) 2013-12-13 2016-04-05 General Electric Company System and method for sub-sea cable termination
EP3034561B1 (fr) * 2014-12-19 2019-02-06 NKT HV Cables GmbH Procédé de fabrication d'un joint de câble CC à haute tension et joint de câble CC à haute tension
JP6870898B2 (ja) * 2015-01-09 2021-05-12 モメンティブ パフォーマンス マテリアルズ ゲーエムベーハーＭｏｍｅｎｔｉｖｅ Ｐｅｒｆｏｒｍａｎｃｅ Ｍａｔｅｒｉａｌｓ ＧｍｂＨ 高圧直流適用のための絶縁体の製造のためのシリコンゴム組成物の使用
FR3050067A1 (fr) 2016-04-08 2017-10-13 Inst Supergrid Nouveau materiau d'isolation electrique
CN106159868B (zh) * 2016-08-03 2018-04-10 清华大学 采用非线性预制橡胶应力锥的交流电缆端头
BR112019005174B1 (pt) * 2016-09-19 2022-10-25 Prysmian S.P.A Junta para cabos de corrente contínua de alta tensão
US11094427B2 (en) 2016-11-15 2021-08-17 Prysmian S.P.A. Electrical field grading material and use thereof in electrical cable accessories
US11476614B2 (en) 2017-05-11 2022-10-18 Prysmian S.P.A. Cable termination system, termination assembly and method for installing such a termination assembly
EP3622600B1 (fr) * 2017-05-11 2023-07-05 Prysmian S.p.A. Système de terminaisons de câble, ensemble de terminaisons et procédé d'installation d'un tel ensemble de terminaisons
CN110770990B (zh) * 2017-06-23 2022-05-27 默克专利股份有限公司 高压直流输电线缆的线缆附件

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US4551915A (en) * 1983-04-06 1985-11-12 Raychem Corporation Method for terminating a high voltage cable
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SE525492C2 (sv) * 2002-10-22 2005-03-01 Abb Research Ltd Fältstyrande polymermatris försedd med fyllning

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Also Published As

Publication number Publication date
SE0602789L (sv) 2008-06-21
WO2008076058A1 (fr) 2008-06-26
SE531409C2 (sv) 2009-03-24
EP2095376A4 (fr) 2010-09-15
CN101563734A (zh) 2009-10-21

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