US3666879A - Power cable - Google Patents

Power cable Download PDF

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Publication number
US3666879A
US3666879A US82248A US3666879DA US3666879A US 3666879 A US3666879 A US 3666879A US 82248 A US82248 A US 82248A US 3666879D A US3666879D A US 3666879DA US 3666879 A US3666879 A US 3666879A
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US
United States
Prior art keywords
cable
conductor
wires
copper
power cable
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.)
Expired - Lifetime
Application number
US82248A
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English (en)
Inventor
Christian Worm Hirsch
John Normann Johnsen
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.)
Alcatel Lucent NV
Original Assignee
International Standard Electric Corp
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 NO443769A external-priority patent/NO133165C/no
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Application granted granted Critical
Publication of US3666879A publication Critical patent/US3666879A/en
Assigned to ALCATEL N.V., DE LAIRESSESTRAAT 153, 1075 HK AMSTERDAM, THE NETHERLANDS, A CORP OF THE NETHERLANDS reassignment ALCATEL N.V., DE LAIRESSESTRAAT 153, 1075 HK AMSTERDAM, THE NETHERLANDS, A CORP OF THE NETHERLANDS ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INTERNATIONAL STANDARD ELECTRIC CORPORATION, A CORP OF DE
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B9/00—Power cables
    • H01B9/006—Constructional features relating to the conductors
    • 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
    • H01B7/14—Submarine cables

Definitions

  • the present invention relates to power cables which are prefabricated to be installed along a certain cable route and particularly to the maintenance of relatively constant properties therealong.
  • the current carrying capacity of power cable is determined by factors such as the properties of the conductor, of the insulation and of the cable surroundings. The most critical of these factors are the properties of the insulation, in particular, its abilities to withstand heat.
  • the cable insulation will in most cases lose its original insulating properties if it is subjected to excessive heat for any period of time.
  • the heat affecting the insulation is determined by the conductor resistance and the heat dissipation properties of the cable insulation and those of the surroundings.
  • a particular cable installed at a particular place must therefore not be loaded to such an extent as to cause deterioration of the insulation. In order to be on the safe side, overdimensioning of cable conductors are quite common.
  • Power cables are usually designed so that the power losses i.e., losses in the conductor, dielectric losses in the insulation, sheath losses etc. are kept constant along the cable at constant current and constant voltage.
  • the power losses i.e., losses in the conductor, dielectric losses in the insulation, sheath losses etc.
  • the heat dissipation properties of the surroundings may vary considerably along a cable route, causing increased cable temperature at places where the heat dissipation properties are poor.
  • the conductor temperature may increase at places such as joints where two cable lengths are joined together. Problems caused by these two factors shall be considered in detail below.
  • the thermal resistivity of the surroundings depends on whether a cable is laid in sand, soil, clay, water, ducts etc. Such varying conditions are taken into account when designing a cable installation, allowing heavier loading of a cable having good heat dissipation possibilities than of one having poor heat dissipation.
  • the thermal resistivity of the surroundings will vary along the cable route.
  • the conductor temperature will vary along the cable. Since the maximum conductor temperature must not exceed a certain limit depending on the type of the cable, the operating voltage etc., these conditions must be taken into account during the dimensioning of the cable.
  • the part of the route having the poorest heat dissipation properties will therefore be the critical factor when determining the cable dimensions.
  • the part of the cable passing through areas with better heat dissipation properties will have a lower conductor temperature than permissible, because these parts are not loaded to their full current carrying capacity.
  • Such overdimensioning is usually very expensive. This is especially the case for long submarine cables, where most of the cable is exposed to very favorable thermal conditions namely the part of the cable which is lying in the water while only a small part at each end of the cable is in the ground under relatively poor thermal conditions and therefore being the critical factor for dimensioning the whole cable.
  • a cable In order to obtain the best possible cable installation, a cable should be designed such that the operating temperature on the cable insulation at all places is just below the maximum allowable temperature. It might, however, be desirable, at joints, to specify a somewhat lower temperature.
  • Conductors for insulated cables in the past normally have been made with copper because of its high conductivity of electric current and low power loss capability.
  • its high cost has prompted a change to less expensive aluminum in spite of the fact that its conductivity is only about 60 percent of that of copper.
  • the change from copper to aluminum for certain types of applications, such as cables for high voltages has been slow. This has been due to certain disadvantages of aluminum as compared to copper, such as its higher thermal coefficient of expansion and more complicated procedure for the joining of conductors.
  • the method of joining the two copper conductors normally consists of placing a copper sleeve over the conductors and compressing this sleeve by means of a hydraulic press, the sleeve thus providing the necessary support to help the conductors stand the repeated bending.
  • An object of the present invention is to provide a more efficient cable by preventing the overdimensioning which follows from using conventional dimensioning methods and to avoid undesirable extra joints.
  • the overdimensioning problem may be taken care of by changing the electrical resistance of the cable conductor in accordance with the thermal resistivity along the cable route.
  • the thermal resistivity or heat dissipation properties should be measured along the cable route, or estimated, at the early planning stage in order to decide which conductor resistance value should be used on the various parts of the route in order to ensure optimum utilization of the current carrying capacity on all parts of the cable.
  • Another object of the present invention is to provide a power cable comprising a conductor made wholly or partly of aluminum, designing the cable lengths such that the temperature at the joints between succeeding lengths is kept aslow as possible. This is obtained according to the present invention by gradually changing the aluminum portion of the conductor cross-section to copper at the ends of each length.
  • the cable conductor is designed such that the electrical resistance per unit length of the conductor, at any point along the cable route, is chosen in accordance with the desired conductor temperature at that particular point.
  • the required change of the electrical resistance of the conductor is obtained by changing partly or wholly from one conductor material to another and vice versa in the longitudinal direction of the conductor.
  • the conductor materials are preferably aluminum and copper and the change of the electrical conductor resistance is achieved while maintaining the geometrical dimensions of the conductor.
  • the conductor temperature within the joint will be much lower than it would otherwise be. This again means that the insulation in and near the joint will operate at a lower temperature than the insulation inthe remaining part of the cable. In most cases this will result in lower dielectric losses.
  • An additional advantage is that the problem of joining two lengths of cable together is greatly reduced, since it is easier to join two copper conductors than it is to join two made of aluminum.
  • the conductor resistance along a cable route where the thermal resistivity of the cable surroundings vary is changed in accordance with the change of thermal resistivity of the cable surroundings by changing the conductor material such that the, geometrical dimensions of the cable is kept constant throughout the cable route.
  • the present invention avoids the mentioned disadvantages of using aluminum as conductor material, while it maintains the savings which are possible by using this conductor material instead of copper. In thiscase of duct installed cables only a few per cent of the cable length need to have copper as conductor material.
  • FIG. 2 is a longitudinal section through a conductor along the conductor axis showing the different cross-sections as illustrated in FIGS. 1a, lb and 1c, and
  • FIG. 3 shows six conductor wires of one layer where the conductor material of the wires is changed over a certain length.
  • FIGS. 1a, 1b and 1c are shown a power cable conductor consisting of a hollow tubular core 1 and two layers 2 and 3 of a plurality of strands of profiled wires.
  • the tubular core 1 and the inner profiled layer 2 are made of aluminum, while the outermost layer 3 is made of copper.
  • the conductor material of the inner layer 2 has been changed to copper, while in FIG. 10 the tubular core 1 is also made of copper.
  • the cross-sections shown in these three figures represent power cable conductors, the conductor material of which is chosen in accordance with a desired temperature on the conductor.
  • the change in conductor material is preferably obtained by designing conductors which in the longitudinal direction is constituted by wires of at least two different conductor materials.
  • the conductor is usually designed as a multistrand conductor, the number of wires constituting the conductor and the geometrical cross-section and shape of these wires are maintained throughout the cable route.
  • the desired changes of the conductor resistance is obtained by changing the conductor material in at least one of the wires.
  • the desired change from one conductor material to another is obtained by splicing wires of different conductor materials together by welding, soldering, compression joining or similar processes prior to working of the wire or conductor to its final cross-section and shape.
  • a short piece of wire made of one of the two metals may be spliced with a short piece made of the other metal in advance, if necessary under laboratory conditions to produce good quality joints, so that only joints between wires of similar metals have to be made during the stranding operation.
  • Another variation of the invention is that in any cross-section of the cable comprising aluminum wires as well as copper wires, the aluminum wires are arranged in the core and in the inner layers while the copper wires are arranged in the other layers.
  • FIG. 2 is shown a cut through a conductor similar to that shown in FIGS. 1a-1c, with sections A-A, B-B and C-C corresponding to those of FIGS. la, lb and 10 respectively.
  • the complete conductor is made of aluminum, while at the right the whole cross-section is changed to copper.
  • the conductor material is not changed abruptly in the whole conductor cross-section.
  • Layers 4, 5 and 7 indicate the aluminum portions of the outermost layer, the inner profiled layer and the tubular core respectively, while 6, 8 and 9 indicate the copper portions.
  • the conductor consists of two or more wires each with a joint of two different metals it is preferable to space the joints of the two metals evenly over a certain length of the conductor in order to avoid abrupt changes of the mechanical and electrical properties of the said conductor.
  • the distance between each joint should be at least 10 cm.
  • FIG. 3 is shown six of the plurality of profiled wires representing six of the 18 wires on the outer multistranded profiled wire layer of the conductor similar to that shown in FIGS. la, lb, 1c and FIG. 2. his considered advantageous to undertake the change from one conductor material to another over a certain length, and in FIG. 3 is illustrated how this may be effected in individual strands.
  • At the extreme left all wires are of aluminum, while at the extreme right all wires are of copper.
  • each wire joint is placed at a certain distance from the neighboring joints, thereby obtaining an interleaved pattern.
  • the joint of wire 13 is placed between unjointed portions of the neighbor wires 12 and 14.
  • the change to copper should preferably be undertaken at points where the cable is still within the duct. Thereby the whole portion of the cable which is subjected to the most severe bending stresses, e.g., the portion located within the manhole, has copper as a conductor material and the many years of experience gained with duct cables with copper conductors may be applied also to an aluminum/copper conductor cable.
  • the change to copper should however, be made close to the entrance of the manhole, for example, one meter within the duct, in order to use the least possible amount of copper.
  • the manufacturing process is facilitated.
  • the conductor Once the conductor has been made, it may be passed through the further manufacturing steps, such as insulating, sheathing and armouring processes, in one pass.
  • a power cable subjected to varying thermal characteristics along a route comprising a plurality of adjoining parallel longitudinal. electrical conductors each having longitudinal sections of aluminum and copper jointed in series, said sections each having a predetermined length and disposition selectively matching the changesin the thermal characteristics along said route to maintain said conductors below a predetermined maximum temperature and to minimize power loss therealong, and said conductors having constant crosssectional dimensions along their length.
  • a power cable according to claim 1 wherein a substantial portion of a length of each said conductor is made of aluminum and the end portions thereof are made of copper.
  • a power cable according to claim 5, wherein the crosssection of the cable comprises aluminum wires and copper wires selectively arranged in inner and outer layers along different longitudinal sections to provide gradual changes of material along the length of cable.
  • a power cable according to claim 8 wherein said joints of adjacent wires around the circumference of said cable are stagger-ed to provide an interleaved pattern along the length of the layer.

Landscapes

  • Insulated Conductors (AREA)
  • Connections Effected By Soldering, Adhesion, Or Permanent Deformation (AREA)
  • Non-Insulated Conductors (AREA)
  • Cable Accessories (AREA)
  • Processing Of Terminals (AREA)
US82248A 1969-11-08 1970-10-20 Power cable Expired - Lifetime US3666879A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO443769A NO133165C (de) 1969-11-08 1969-11-08
NO41770 1970-02-06

Publications (1)

Publication Number Publication Date
US3666879A true US3666879A (en) 1972-05-30

Family

ID=26647376

Family Applications (1)

Application Number Title Priority Date Filing Date
US82248A Expired - Lifetime US3666879A (en) 1969-11-08 1970-10-20 Power cable

Country Status (10)

Country Link
US (1) US3666879A (de)
JP (1) JPS4827552B1 (de)
AT (1) AT309555B (de)
BE (1) BE758654A (de)
CA (1) CA930825A (de)
CH (1) CH521005A (de)
DE (1) DE2054170B2 (de)
ES (1) ES385341A1 (de)
FR (1) FR2067048B1 (de)
HU (1) HU166294B (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2231082A1 (de) * 1973-05-22 1974-12-20 Int Standard Electric Corp
US3949154A (en) * 1973-08-02 1976-04-06 Felten & Guilleaume Kabelwerke Ag Internally cooled high-voltage high-energy cable
US3988526A (en) * 1973-04-05 1976-10-26 Felten & Guilleaume Kabelwerke Ag Internally cooled high-voltage high-energy cable
US3989884A (en) * 1974-08-02 1976-11-02 Felten & Guilleaume Carlswerk Ag Internally cooled high-energy cable and a method of manufacturing same
US4043031A (en) * 1974-08-02 1977-08-23 Felten & Guilleaume Carlswerk Ag Method of manufacturing internally cooled high-energy cable
US4761517A (en) * 1986-05-05 1988-08-02 Commissariat A L'energie Atomique Electrical connections with controlled thermal and electrical resistances
US6428858B1 (en) 2001-01-25 2002-08-06 Jimmie Brooks Bolton Wire for thermal spraying system
US20090260852A1 (en) * 2008-02-29 2009-10-22 Fort Wayne Metals Research Products Corporation Alternating core composite wire
WO2017039590A1 (en) * 2015-08-28 2017-03-09 Abb Technoloy Ag Hybrid conductor
US20180266049A1 (en) * 2015-11-17 2018-09-20 Furukawa Electric Co, Ltd Stranded conductor and method for manufacturing stranded conductor
US20210359477A1 (en) * 2017-02-17 2021-11-18 Snaprays, Llc Dba Snappower Active cover plates

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1006573A (fr) * 1948-02-04 1952-04-24 Procédé d'amélioration des contacts pour la substitution de l'aluminium au cuivre dans les conducteurs électriques
US2992959A (en) * 1958-02-20 1961-07-18 Kanthal Ab Production of shaped bodies from heat resistant oxidation proof materials
US3094679A (en) * 1960-01-13 1963-06-18 Carborundum Co Silicon carbide resistance body and method of making the same
US3263193A (en) * 1964-10-19 1966-07-26 Richard J Allen Superconducting to normal conducting cable transition
US3317651A (en) * 1964-12-11 1967-05-02 Philips Corp Low temperature device with a current supply member

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1031863A (en) * 1963-12-04 1966-06-02 Rosemount Eng Co Ltd Improvements in or relating to electrical conductors and their manufacture

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1006573A (fr) * 1948-02-04 1952-04-24 Procédé d'amélioration des contacts pour la substitution de l'aluminium au cuivre dans les conducteurs électriques
US2992959A (en) * 1958-02-20 1961-07-18 Kanthal Ab Production of shaped bodies from heat resistant oxidation proof materials
US3094679A (en) * 1960-01-13 1963-06-18 Carborundum Co Silicon carbide resistance body and method of making the same
US3263193A (en) * 1964-10-19 1966-07-26 Richard J Allen Superconducting to normal conducting cable transition
US3317651A (en) * 1964-12-11 1967-05-02 Philips Corp Low temperature device with a current supply member

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Dummer et al., Wires & R.F. Cables, Pitman, 1968, p. 129 *

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3988526A (en) * 1973-04-05 1976-10-26 Felten & Guilleaume Kabelwerke Ag Internally cooled high-voltage high-energy cable
FR2231082A1 (de) * 1973-05-22 1974-12-20 Int Standard Electric Corp
US3909501A (en) * 1973-05-22 1975-09-30 Int Standard Electric Corp Hollow conductor power cable
US3949154A (en) * 1973-08-02 1976-04-06 Felten & Guilleaume Kabelwerke Ag Internally cooled high-voltage high-energy cable
US3989884A (en) * 1974-08-02 1976-11-02 Felten & Guilleaume Carlswerk Ag Internally cooled high-energy cable and a method of manufacturing same
US4043031A (en) * 1974-08-02 1977-08-23 Felten & Guilleaume Carlswerk Ag Method of manufacturing internally cooled high-energy cable
US4761517A (en) * 1986-05-05 1988-08-02 Commissariat A L'energie Atomique Electrical connections with controlled thermal and electrical resistances
US6861612B2 (en) 2001-01-25 2005-03-01 Jimmie Brooks Bolton Methods for using a laser beam to apply wear-reducing material to tool joints
US6428858B1 (en) 2001-01-25 2002-08-06 Jimmie Brooks Bolton Wire for thermal spraying system
US20090260852A1 (en) * 2008-02-29 2009-10-22 Fort Wayne Metals Research Products Corporation Alternating core composite wire
US7989703B2 (en) 2008-02-29 2011-08-02 Fort Wayne Metals Research Products Corporation Alternating core composite wire
WO2017039590A1 (en) * 2015-08-28 2017-03-09 Abb Technoloy Ag Hybrid conductor
US20180266049A1 (en) * 2015-11-17 2018-09-20 Furukawa Electric Co, Ltd Stranded conductor and method for manufacturing stranded conductor
US10458064B2 (en) * 2015-11-17 2019-10-29 Furukawa Electric Co., Ltd. Stranded conductor and method for manufacturing stranded conductor
US11566371B2 (en) * 2015-11-17 2023-01-31 Furukawa Electric Co., Ltd. Stranded conductor and method for manufacturing stranded conductor
US20210359477A1 (en) * 2017-02-17 2021-11-18 Snaprays, Llc Dba Snappower Active cover plates
US12021335B2 (en) * 2017-02-17 2024-06-25 Snaprays, Llc Active cover plates

Also Published As

Publication number Publication date
JPS4827552B1 (de) 1973-08-23
FR2067048B1 (de) 1974-10-11
DE2054170A1 (de) 1971-05-19
BE758654A (fr) 1971-05-10
DE2054170B2 (de) 1979-05-10
CH521005A (de) 1972-03-31
FR2067048A1 (de) 1971-08-13
CA930825A (en) 1973-07-24
ES385341A1 (es) 1973-07-16
AT309555B (de) 1973-08-27
HU166294B (de) 1975-02-28

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Legal Events

Date Code Title Description
AS Assignment

Owner name: ALCATEL N.V., DE LAIRESSESTRAAT 153, 1075 HK AMSTE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:INTERNATIONAL STANDARD ELECTRIC CORPORATION, A CORP OF DE;REEL/FRAME:004718/0023

Effective date: 19870311