WO2013112781A1 - Conception de câble électrique - Google Patents

Conception de câble électrique Download PDF

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Publication number
WO2013112781A1
WO2013112781A1 PCT/US2013/023050 US2013023050W WO2013112781A1 WO 2013112781 A1 WO2013112781 A1 WO 2013112781A1 US 2013023050 W US2013023050 W US 2013023050W WO 2013112781 A1 WO2013112781 A1 WO 2013112781A1
Authority
WO
WIPO (PCT)
Prior art keywords
tree
ply
retardant
polymer composition
xlpe
Prior art date
Application number
PCT/US2013/023050
Other languages
English (en)
Inventor
Alfred Mendelsohn
Original Assignee
Alfred Mendelsohn
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
Priority claimed from US13/748,100 external-priority patent/US20140202732A1/en
Application filed by Alfred Mendelsohn filed Critical Alfred Mendelsohn
Publication of WO2013112781A1 publication Critical patent/WO2013112781A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
    • H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
    • H01B7/2813—Protection against damage caused by electrical, chemical or water tree deterioration
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/28—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances natural or synthetic rubbers

Definitions

  • This invention relates to power cable designs for medium and high voltage applications.
  • it relates to the insulation layer of such power cable designs and the layer's use for the prevention or retardation of water trees.
  • a filled elastomeric insulation has been used as an alternative to thermoplastic polyethylene insulation.
  • the polymer component of the filled elastomeric insulation is typically ethylene propylene copolymer or ethylene propylene diene terpolymer.
  • EPR these filled elastomeric insulations are referred to as "EPR" insulation.
  • EPR insulation When compared to unfilled XLPE insulation, an EPR insulation provides improved high temperature deformation resistance and increased flexibility.
  • a "water tree” is defined as a diffuse structure in a dielectric insulating material with an appearance resembling a bush or a fan. (E.F. Steennis and F.H. Kreuger, "Water Treeing in Polyethylene Cables," IEEE Transactions on Electrical Insulation, Vol. 25, No. 5, p. 989 (Oct. 1990). It is believed that physical or chemical contamination or defects in the insulation or at the inner semiconductive shield layer surface, in the presence of moisture and a stress enhancement of the electrical field causes water treeing.
  • vented water trees initiate from the surface of the semiconductive shield layers and grow into the insulation layer.
  • Bo-tie trees grow from defects inside the insulation layer and in both directions aligned with the electric field. It is believed that the most detrimental water trees are vented water trees that grow from the inner semiconductive shield layer, which is the area of greatest electrical stress.
  • EPR insulations would have improved resistance to water treeing.
  • TR-XLPE tree retardant XLPE materials were developed and generically referred to as TR-XLPE.
  • TR-XLPE tree retardant XLPE materials were developed and generically referred to as TR-XLPE.
  • PEG polyethylene glycol
  • EP 0179845 polar ethylene alkyl copolymer
  • the approach incorporating the PEG additive was been referred to as additive TR-XLPE.
  • copolymer TR-XLPE copolymer TR-XLPE.
  • the Insulated Conductors Committee Discussion Group A4D an industry committee, has worked on defining TR-XLPE performance and determined that after subjecting TR-XLPE insulated cables to the Accelerated Water Treeing Test (AWTT) for 1 or 2 years of accelerated aging, the resulting vented water trees were typically shorter than 10 mils (0.25 mm). In conventional XLPE cables, the length of vented water trees were significantly in excess of 20 mils (0.5 mm).
  • vented water tree length be less than 20 mils after accelerated aging. See S. Pelissou, et al., "A Review of Possible Methods for Defining Tree Retardant Crosslinked Polyethylene (TRXLPE),” IEEE Electrical Insulation Magazine. Vol. 24, No. 5, pp. 22-30 (Sep. 2008).
  • the insulation layer is generally made from a fully-formulated TR-XLPE compound which contains or is prepared using a tree retardant additive, antioxidants, other functional additives such as cure boosters, and an organic peroxide as the chemical crosslinking agent.
  • the power cable manufacturers turned to the use of three extruders to form an extruded cable core, wherein the inner semiconductive shield layer (210), the insulation layer (220), and the outer semiconductive shield layer (230) were coextruded simultaneously over the metal conductor (240), which is pulled through the triple-crosshead die (250). See Fig. 2.
  • the extruded cable core was then immediately passed through a continuous vulcanization (CV) tube (260) under pressurized nitrogen.
  • the heated CV tube exposed the cable core to very high temperatures, thereby causing the three cable layers to crosslink.
  • the cable core passed through a cooling tube (270) to cool the cable core sufficiently for coiling the cable core on reels (280) without deformation.
  • the neutral layer and the outer jacket were applied over the cable core to yield the finished power cable.
  • Silane curing takes place in the solid state, after cable extrusion, by exposing the cable insulation to moisture and elevated temperature in the range of 70-90 degrees Celsius. Essentially, the steps of extrusion and crosslinking are decoupled. While the decoupling allows the cable extrusion to occur at higher rates, moisture-cured cables are yet to match the performance of CV-cured TR-XLPE cables.
  • DPI Direct peroxide injection
  • the organic peroxide chemical crosslinking agent is directly injected into the extruder.
  • a significant advance to the DPI process involves a precision feeding system and an inline premixer.
  • the base polymer, the crosslinking agent, and the other additives in liquid form are premixed.
  • polyethylene glycol for additive TR-XLPE compounds does not premix effectively into the compound.
  • the copolymer for copolymer TR-XLPE compounds does not distribute well at the microscale level. Accordingly, effective performance has proven elusive.
  • U.S. Patent No. 3,792, 192 discloses a two-ply insulation layer for providing improved corona discharge.
  • the disclosed cable construction uses an inner layer of EPR insulation such as ethylene-propylene copolymer or ethylene-propylene-diene terpolymer and an outer layer of XLPE insulation.
  • EPR layer provides corona resistance on the inside of the insulation, where the electrical stresses have their highest values and the conductor generates high temperatures.
  • the inner layer is an expensive, higher electrical field strength material while the outer layer is a less expensive, lower electrical field strength material.
  • U.S. Patent 5,575,965 discloses a two-ply insulation layer where the inner layer is a homogeneous polyethylene formulation, having improved melt-fracture characteristics when compared to a single layer insulation based on homogeneous polyethylene.
  • Homogeneous polyethylene-based compositions are known to experience a phenomenon described as melt fracture in which, upon exiting the extruder die, the extrudate has a highly irregular, rough surface.
  • the inner layer based on a homogeneous polyethylene formulation had a thickness generally in the range of about 30 to about 200 mils.
  • the outer layer became a formulation containing one of three different polymers: (i) a copolymer of ethylene and an unsaturated ester; (ii) a high pressure polyethylene; or (iii) a very low density polyethylene.
  • the outer layer was generally at least about 5 mils in thickness, with the upper limit being a matter of economics and application.
  • WO 99/44206 Al discloses an insulation layer having inner and outer polar-enriched surface zones for use in a high-voltage, direct current cable.
  • the use of the insulation layer is believed to decrease the mobility of space charges, reduce space charge accumulation, increase the capability to withstand charge injection, and control any developing space charge profile or pattern.
  • the published application does not clearly indicate how the polar-enriched surface zones are achieved, whether through a multi-ply process or some other process. In any event, the polar-enriched surface zones were not employed to combat water trees.
  • the present invention is a power cable construction having a metal conductor and an multi-ply insulation layer, among other layers, over the metal conductor.
  • the multi-ply insulation layer has at least two plys, wherein the first, inner tree-retardant ply is made from or contains a tree-retardant polymer compostion and the second, outer ply is made from or contains a conventional polymeric insulation composition.
  • the present invention provides improved insulative properties for power cables and opportunities for processing and costs improvements. These improvements may be realized through composition, design, or manufacturing choices disclosed herein.
  • FIG. 1 is a perspective view of an electrical cable according to a typical medium voltage cable design.
  • FIG. 2 is a schematic of a typical continuous vulcanization extrusion process for preparing a cable core of a typical medium voltage cable.
  • FIG. 3 is a perspective view of an electrical cable according to the presently-invented voltage cable design.
  • the present invention is a power cable construction having a metal conductor and an multi-ply insulation layer, among other layers, over the metal conductor.
  • the multi-ply insulation layer has at least two plys, wherein the first, inner tree-retardant ply is made from or contains a tree-retardant polymer compostion and the second, outer ply is made from or contains a conventional polymeric insulation composition.
  • the multi-ply insulation layer may use a TR-XLPE composition as the composition for making the first, inner tree-retardant ply and a conventional XLPE composition for making the second, outer ply.
  • the multi-ply insulation may use a tree retardant EPR as the composition for making the first, inner tree-retardant ply and a conventional EPR composition for making the second, outer ply.
  • a tree retardant EPR as the composition for making the first, inner tree-retardant ply
  • suitable outer layers include, for example, unfilled or lightly filled elastomers.
  • the use of the described multi-ply insulation layer would contain (a) a metal conductor (310), (b) an inner semiconductive shield layer (320), (c) a multi-ply insulation layer (330) having an (i) first, inner TR-XLPE ply (333) and (ii) a second, outer XLPE ply (337), (d) an outer semiconductive shield layer (340), (e) a neutral layer (350), and (f) an outer jacket (360). See FIG. 3.
  • the present invention contemplates that the thickness of the first, inner tree-retardant ply of the multi-ply insulation layer should be sufficient to encompass a 10-mil vented water tree.
  • the thickness of the first, inner tree-retardant ply can be less than about 50 miles, preferably less than about 30 mils, more preferably less than about 25 mils, and most preferably less than about 20 mils.
  • the second, outer ply of the insulation layer can be in the range of about 175 mils to about 345 mils for most medium voltage constructions. It is contemplated that other power cable applications may require smaller or larger thicknesses of the second, outer ply.
  • a tree-retardant polymer composition may be used as a first, inner ply to prevent electrical treeing at the source of the greatest electrical stress on high voltage power cables, by incorporating electrical tree retardant additives into the insulating polymer composition.
  • the present invention is a process for making a power cable construction having a metal conductor and an multi-ply insulation layer, among other layers, over the metal conductor.
  • the multi-ply insulation layer has at least two plys, wherein the first, inner tree-retardant ply is made from or contains a tree-retardant polymer compostion and the second, outer ply is made from or contains a conventional polymeric insulation composition.
  • the first, inner tree-retardant ply is made using conventional premixing techniques to prepare a crosslinkable, TR-XLPE composition for co-extrusion through a multi-crosshead extruder, typically a quadruple-crosshead extruder.
  • the second, outer ply may be prepared inline using direct peroxide injection technology with a polyethylene base resin.
  • a premixer is utilized in the DPI process to add and disperse the chemical crosslinking agent and other components into the polyethylene base resin inline, prior to extrusion.
  • a compounded TR-XLPE formulation without the peroxide may be supplied to the extruder and the peroxide may be added using the DPI approach.
  • a quadruple-crosshead extruder forms an extruded cable core, having (i) an inner semiconductive shield layer, (ii) a multi-ply insulation layer with (a) a first, inner tree-retardant ply and (b) a second, outer conventional ply, and (iii) an outer semiconductive shield layer coextruded simultaneously over a metal conductor, which is pulled through the quadruple-crosshead die.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Organic Insulating Materials (AREA)

Abstract

Par l'utilisation d'une couche d'isolation multicouche, le câble électrique résultant retient la résistance à l'arborescence aqueuse ou électrique des câbles électriques retardateurs d'arborescence même si une composition d'isolation polymère classique remplace essentiellement la composition de polymère retardatrice d'arborescence. Un procédé amélioré qui tire profit du système multicouche est également décrit.
PCT/US2013/023050 2012-01-25 2013-01-25 Conception de câble électrique WO2013112781A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201261590476P 2012-01-25 2012-01-25
US61/590,476 2012-01-25
US13/748,100 US20140202732A1 (en) 2013-01-23 2013-01-23 Power cable design
US13/748,100 2013-01-23

Publications (1)

Publication Number Publication Date
WO2013112781A1 true WO2013112781A1 (fr) 2013-08-01

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2013/023050 WO2013112781A1 (fr) 2012-01-25 2013-01-25 Conception de câble électrique

Country Status (1)

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WO (1) WO2013112781A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103824642A (zh) * 2014-02-10 2014-05-28 国家电网公司 具有耐湿老化性的柔性电力电缆
CN107958730A (zh) * 2017-11-23 2018-04-24 唐山华通特种线缆制造有限公司 一种35kv及以下xlpe绝缘热固性护套中压阻水电缆及生产工艺
US11031153B2 (en) 2018-11-05 2021-06-08 General Cable Technologies Corporation Water tree resistant cables
WO2023244498A1 (fr) 2022-06-16 2023-12-21 Dow Global Technologies Llc Méthode de fabrication de compositions de composé réticulable à ultra-haute température, faible échauffement

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4087486A (en) * 1975-05-15 1978-05-02 Standard Oil Company (Indiana) Polypropylene composition containing EPR
JPH09265842A (ja) * 1996-03-27 1997-10-07 Fujikura Ltd 電気ケーブル
RU2323494C2 (ru) * 2003-01-20 2008-04-27 Пирелли Энд К. С.П.А. Кабель с повторно перерабатываемым слоем покрытия
RU90254U1 (ru) * 2009-09-03 2009-12-27 Общество с ограниченной ответственностью "Сарансккабель-Оптика" Огнестойкий кабель
CN201749698U (zh) * 2010-07-31 2011-02-16 广东电缆厂有限公司 一种抗干扰的船用特种仪表回路电缆

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4087486A (en) * 1975-05-15 1978-05-02 Standard Oil Company (Indiana) Polypropylene composition containing EPR
JPH09265842A (ja) * 1996-03-27 1997-10-07 Fujikura Ltd 電気ケーブル
RU2323494C2 (ru) * 2003-01-20 2008-04-27 Пирелли Энд К. С.П.А. Кабель с повторно перерабатываемым слоем покрытия
RU90254U1 (ru) * 2009-09-03 2009-12-27 Общество с ограниченной ответственностью "Сарансккабель-Оптика" Огнестойкий кабель
CN201749698U (zh) * 2010-07-31 2011-02-16 广东电缆厂有限公司 一种抗干扰的船用特种仪表回路电缆

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103824642A (zh) * 2014-02-10 2014-05-28 国家电网公司 具有耐湿老化性的柔性电力电缆
CN107958730A (zh) * 2017-11-23 2018-04-24 唐山华通特种线缆制造有限公司 一种35kv及以下xlpe绝缘热固性护套中压阻水电缆及生产工艺
US11031153B2 (en) 2018-11-05 2021-06-08 General Cable Technologies Corporation Water tree resistant cables
WO2023244498A1 (fr) 2022-06-16 2023-12-21 Dow Global Technologies Llc Méthode de fabrication de compositions de composé réticulable à ultra-haute température, faible échauffement

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