CA2220113A1 - Non-water permeating power transmission cable - Google Patents
Non-water permeating power transmission cable Download PDFInfo
- Publication number
- CA2220113A1 CA2220113A1 CA002220113A CA2220113A CA2220113A1 CA 2220113 A1 CA2220113 A1 CA 2220113A1 CA 002220113 A CA002220113 A CA 002220113A CA 2220113 A CA2220113 A CA 2220113A CA 2220113 A1 CA2220113 A1 CA 2220113A1
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- CA
- Canada
- Prior art keywords
- cable
- filling compound
- filling
- conductor
- water
- 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.)
- Abandoned
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
- H01B13/32—Filling or coating with impervious material
- H01B13/322—Filling or coating with impervious material the material being a liquid, jelly-like or viscous substance
- H01B13/323—Filling or coating with impervious material the material being a liquid, jelly-like or viscous substance using a filling or coating head
- H01B13/325—Filling or coating with impervious material the material being a liquid, jelly-like or viscous substance using a filling or coating head in combination with vibration generating means
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- 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
- H01B7/282—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
- H01B7/285—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable
- H01B7/288—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable using hygroscopic material or material swelling in the presence of liquid
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A30/00—Adapting or protecting infrastructure or their operation
- Y02A30/14—Extreme weather resilient electric power supply systems, e.g. strengthening power lines or underground power cables
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Insulated Conductors (AREA)
- Medicinal Preparation (AREA)
Abstract
A power transmission cable (10) and method of making such cable including first (44) and second filling (20) compounds which function to prevent degradation in cable performance as a result of the permeation of water through the polyethylene sheath (14) of the cable (10) and which do not liquefy at high temperature. The first filling (44) compound includes a gel matrix having a water reactive polymer dispersed therein and fills the space inside the outer jacket (14) of the cable and outside of the metallic shield (38) that surrounds the conductor(s) (12). The second filling compound includes a gel matrix and water reactive polymer, as well as a material which makes the second compound electrically conductive, and fills the space between the conductor (12) and the insulation surrounding (30) the conductor (12) or, in the case of a cable (10) having multiple, or stranded, conductors (12), the spaces between conductors as well as the space between the bundle of conductors (12) and the insulation (30).
Description
NON-WATER PERMEATIMG POWER
TRANSMI~SION CABLE
The present invention is for a power transmission cable for alternating current (AC). More particularly, the present invention is a power cable which is not subject to the deficienc:ies in ins ulation which result from the invasion of water into conventional power transmiss;on cables.
The phenomenon of water permeation of power transmission cable insulation is well documented (treeing).
Briefly, this phenomenon results from permeation of water vapor through the polyethylene insulation of power cables and sub,sequent condensation of the vapor inside the polyethylene insulation sheath . The accumulated, condensed water fac ilitates an electrochemical event that leads to the degradation of cable performance as more completely described in U.S. Patent No.
TRANSMI~SION CABLE
The present invention is for a power transmission cable for alternating current (AC). More particularly, the present invention is a power cable which is not subject to the deficienc:ies in ins ulation which result from the invasion of water into conventional power transmiss;on cables.
The phenomenon of water permeation of power transmission cable insulation is well documented (treeing).
Briefly, this phenomenon results from permeation of water vapor through the polyethylene insulation of power cables and sub,sequent condensation of the vapor inside the polyethylene insulation sheath . The accumulated, condensed water fac ilitates an electrochemical event that leads to the degradation of cable performance as more completely described in U.S. Patent No.
2 0 5,010,209 and a corresponding European patent application published under EP 0 416 728 A2. The patent literature describes attempts to solve this well known problem which is exemplified in U.',. Patent No. 4,703,132. However, even in view of the aforementioned U.S. patent and corresponding European pa~ent 2 5 application, the problem persists, indicating that although it is we:ll known and that attempts have been made to overcome it, the problem has not yet been solved.
The present invention is directed to that same problem and improves on the approach taken on the patent documents listed in 3 0 the preceding paragraph. Specifically, U.S. Patent No. 4,703,132 describes a filling compound, and a cable containing that compound, which comprises a low molecular weight rubber adrnixed with a sprinkling of fine particles of a material applied over the filling compound which swells when it absorbs water and 3 5 which is said to be soft enough to be applied to the conductor wil:hout the use of extrusion equipment. As set out in that pal:ent, the filling compound is applied to the conductor wires as t!hey are brought together in concentric layers and then, as the wires ha ving the filling compound therearound are brought together, the outer surface of the conductor bundle is covered by extrusion with a conventional semiconducting stress control layer which completely fills the interstices in the outer layer of wires. A
semiconducting rubber filled tape is then applied, followed by a layer of extruded insulation, and other layers all as described in more detail in column 2 of that patent.
As the filling compound described in Patent No. 4,703,132 is applied over a layer of wires, the filling compound is exposed to fine particles of a water swellable material by passing the layer of 1 0 wires having the filling compound applied thereto through a chamber containing such particles as they are being blown about in such a manner that the particles adhere to the exposed filling compound. That patent (in column 3) also suggests that the water swellable powder could be mixed with the filling compound and 1 5 then applied to the conductor(s) in that same manner. However, that patent gives no instruction as to how to make that mixture or how a mixture of powder and filling material would function to solve the aforementioned-mentioned problem in light of the highly hydrophobic character of the filling compound. In effect, 2 0 the filling compound is so hydrophobic that it prevents interaction between the powdered water absorber and the water.
Although the invention described in that reference is stated to have been made for the purpose of overcoming the above-characterized treeing problem, that it did not do so is made clear 2 5 by the existence of U.S. Patent No. 5,010,20g, which issued to the same party as U.S . Patent No. 4,703,132, and which addresses this same treeing problem. Patent No. 5,010,209 discloses the use of the same filling compound and water swellable material, but with so-called helical elongated metal elements disposed around the 3 0 insulation shield, each of the metal elements having particles of a water swellable material at least at the adj acent edges of the metal elements. Just as Patent No. 4,703,132 did not provide the solution to the treeing problem, No. 5,010,209 did not provide the solution either.
3 5 The manufacture of cable such as the cable described in U.S.
Patent No. 4,703,132 is also problematical. When the polyethylene sheath, or jacket, of such cable is extruded onto the conductors that have been coated with the filling compound, it is a. a te~per~ u~ which i5 hig!~ enouc~ o m~.lt ~he f'.~ 4 ~omp~und ~u~ rk a~ o~t r~ w~e~- s~el~ m~ rial d~sc:~ b~ tl~. Patent) ~plif~d to ~he ou~iAe o~ th~
concIL;c' o~. C~nJequen~ly, it i..~ ~cc~.~;sary either to t~k~
~eps ~uriI~g m~nufactu~ pr~ ve tk~ I i.l~ ng c:c~m~ound ~'~ om sxpo~u~ o ~ pe; a~ c_ o~ c ~il1in~ ~omE~ouncl i~
nccd~d whi~h dcic~5 no~ mel~.
Ac;ccrding ' o I his ~ r.~ent lon ~h~e is pro~rided ~L
pc~we~ n~ -sion cc.ble C~mFri;ai~g at lza5t OrlR c;ent;ral ~ond~cto~ ? aye~ o~ s~lat~on ~o~lnd ~LC~ cond~c~:or(~;
a m~tallic ~n~lor ~ st:ic 5~1if~ ove~ the 1aye~ o~
in~laticn, a polynerl~ ;,h2~h ~r~und 'hG shioldi ~i ~i.rst f illin~ -om.pG~nd l~c~:c~ ~r~c~c~n S.~ polynl~ri~ 3t~ !th znd s~id ~ iel~ d c secoi1d ~ nq compou3ld ~ ocated bet-~een s~id centra; c~olndu~~-.r ~nd ~ yer c,f ~n~ul~iGn wh~-ei~
the f i -~t, ~ c~ c~pc~.~r.~ co::lpris~ a dielect-ic g~l h~-~ing a wate~ ac~.iv~ ~a~yme?~ ~lisper=,ed ~h~rein and said s~con~ fil~ ing co:~po~nd con~prlses ~ ~el ILa\~ing ~ w~Lte~
reacti~ po3.ymcr ar.~ a cor,u~.ctirlCJ o~ ~emi-concluc~: ng r.,~er~ pers~d ~h~rei~.
Pr~.f cra~iy the c,~le c:o~r.prises ~ plural .lty o*
cen~ral conduc~rs ancl ~as second ~illincs ~o~pG~md: o~t~cl in 1:he spaces ber~ee~ ~h~ c~ndu~o~ sel cf ~he rlrst ~i' ling ~o~npound and o~ th~ s~~cn~ fill_n~ ccmpolln~ r.ay con~prise ~n oil ~ a thi~Xener.
Pr~r~bly th~ sh~.'d i~, me~ d the po:Lymer~o sheath i~ of polv~thylene.
Tlle i r.v~ntl on ~1 so p~ov ~' des a m6thod o~
~r.anu~acturing ~ p~ n~is;.ion cable co~..prising th2 st~ps o~ m~king fi.st aTl~ se~ li.n~ compoun~ls, ~h~
first ~ compourld ~ein~ ~d~ by dispers ~ ng a tJa~_er-a~sor~ing p~ly~ner in a non-h.o;at-melting gel matrix, ,~nd the second f illing c~npound beinq ~3ade ~y ~i~p~rsin~ w~ter-a~sor~c,lt polymz. ~ncl ~ ~oon~i-Actin~J Or .~ c~nducti n¢~
~te~ial in ~ no~.-nc~ melt_nq ~e~ ri.x, ~o~cin~ t:h6 s.~ncl ~ g _¢~n~pour.d in o a ~h~ r under pressur.e ~nd r.~ovi~ one or ~.o~c o onduc:tors ~hrou~;h t~ press~ ;ed r~¢~ ~ ontraU~ ln ~h~ ch;1~nb~l: ~y p~s~irLg the conduc~:or~s) thro~h entry and ¢Xit op~nin~3 in ~l~e ~ha~bla.r so t~ t t;~c~
sc~c~ond t-~ . ~ing compollnd is ~ n~ or~ t~ ~he corlducL;~r(~;), and~o~ int~ th~ cc~ bct~e~n the ~ond~ct3rs ~pp~ yi.ng A~su'ation ~h=~to and ,. metall~c ~lnd/or pIastic ~hield ~Lnd an ou~e.~ ~ol~ ric .~-.hc~,i..h an~ n~ ~ he sp~ce outs:ld~ o~
- the s~,ie' d ,~ n~;iclc Gf '~he outcr po.l ym-ri c sheat~l witn the f i r~ n~ compo~rl~.
' t r.as ~cen ~o~n~ t.~a~ pt e~'crred ~npocimen~s o~ th~
in~cr.t~cn pl-ov~le ~ po~r ~a~smi ~ion ca}~le that d~es not s~4;er ~ rom '_he a ,-ye~ ur-s~lYed problem o~ mt~ist~t~ d~c:~d dt~gra~ion in t~,~ per~ornl~.nce o~ po~lle-- tr~ns~issior~ cable insula~i sn. ~rh~ pref~r~ed ~:ablta is fillc~ With a colnpcsitio~ whic~ does nct ~nt l ~ at the ter..p~ratur2s a~
~h .ch i,~lsul~ition i~ x- rud~ nto r~hc! cable. A pre~'rerr.ed embodt~el~ o~ th~ in-~en~:ion compri~es a cablt~ h~vl~g a CO~t-~
ca~r.p. ised of' one or :rt~ ~ condu~;tors ~ ~ 1 ayer of i nsu Latior ~ro~nd th~ c:s2~dut;to~ls), a mt~t~lliG ~nd/or plas~ic s~hield ~o,,nd the )~~ulat-~on laye, ~ pc~ it- sl~ h which i5 ex~r~lded t~ver tne skicl~, c,r.d 4WO ~illin~ comvoun~s.. '~hc =pC cP b~t-rJs~n the ~olyme~i~ she~h ~.nd t~e c~t~id~ o~ t he rr,ct.a~1ic or pl~ s!lielt i~ ~ille~ witl: c~ ~,r~it ~.ill..~g cGmpound, w~ich is co~pri5ec~ cf a non-hcat me.~tillg, d.ielec:~ric ~.,e1 r~l~tr~ x ..~nd ~ w;3 t~r a~scr~in~ poly~ner., 1:he er ~so..~ing po' ym~r beir.g c~ ~ h~ tyF:~ kno~n as ~ ~uper a.hsor~r ~ n~ch i~; c~prisk~ of ~ polyme~ic bzck~one ha~ g p~rLdan~ io~Lc sroups n~h~ c~s t~r~twc~3n the conductor (s~, and the space }~tween th~ csnductor (s~ ~nd ~h~ innerr~ost ~eta~ lic or pl~s,l~: shleld, is fillc~ h t~e ~-econà
f.ill ins cc~Lpclund, ~1 ~ ch is comprised o~ ~enerally ~he ~;3,~
m~e~ia.~s ~s compr~ ~e the ~lr~t filling com~po~lr;d, speci~ically/ z nsn-hea~ elti;~ 1 rnatr~x havtn~ a ~er =
a~t~r~ ,t~ly~e~ di~p~rs~d ~ r~.in, alld wl~ic.'l ~lso irlcludeS ~ t;~nt~ic~in~ or ~emi-~,orldl~ct~ .at~ridl.
~ rh~ ~inV~n~ o~ hC~ dBscrib~d by way o~
~x-,~r..plc t~ e~t~renc~ r,~ t~e t~r~in~ n whic}~:
F~GUI~ 1 is d ~r;o~h~ tic Lepres~nta.ion cf a metnod and app~ra.u~ f or m~ki~tg a ~ow~l ~ransmisslon ca~l~
inC~ di~ lC~ gc!~ composition o~ ~ he present lnv~ntiorl, ~nd FIC.~!~E 2. is a cu~ ~sway pers~ect~ve ~ie~ of a power oabl~3 typ~ ~Jkich L~ dc ~.th 'ch~ appar~:us or ~igurt~ 1.
.~ will b~. d~srribed .ht i~vt3ntion provi~es 3 cable r:~vin~c r~ ins Co:~pcuhd~ ~ach ~ ing co;;~po~nd compr~ s a ~el having ~ whter _~ac;tiv~: pclymer dispersed l:here i n. ~rhc ~cconc~ or the t~o f i lling t;o;npoundc ~da ~ ~ iona ! ly co~pr i ses ~ sem -.-o~d~lctihg or ~:ond~cti~g a t ~
T~ g~.~ oS both tht~ fir~t: anG second fill~ ng co~npoun~s ol the ca'~l~ of .he p-e~nt i~vention r likt~ th~t o~ prior l i.lling compounds for .x.~h c:~le, is characte~is~t~
~s b~ nt~ hvd-ophobic and ~he~-efo~ e provides an ini~
bar_ ie.r r.o Ihe sp ead and/ or r~.ig~tion o~ we,te:r .in the ~a~ t? . ~Gw~ver, w~en in the ~r~cnce o~' w~ter, ~he f ine powder~ ;c poiy~ner gr~ ;es in ~he sel of t~e ~able of the refer.-ed embodimants o. ~,he pres~n~ lnvent' on ~ravel to ~he w~ di~cerlt the ~el ~atrix. l~his er~e~ct ~ s ~a~ilitc~ted by the addition o~ 2 hy~roF~illic substan~e to the gel, which ~ llows ~he relecLse cf th~ water absor~nt ~oly~;~er tO ~ee~; out the wa~er ~lue to the electroche~ ~al ,~ttr3ction ~:3tw~e,n tlle w~te~ ~so!ecules an¢~ ~he ionic ~xc~Ess ~f the wat~r a~sor~ent: E~olylnor. once th~3 water is c~nt~:ted b~ the polymer that i ;~ re~ eafie~d fr~m the ~al, a highly vlsc~c~u5 mat~ria1 for3~s as él r¢sult o~ l~inding of the -~a~er by the polymer w~ich i 5 ~ TI incapable o~ fl~id rnove,~ent un~er ~he hyd~ os~tatic pr~ssures n~rmally 6,xerte~l on pow~r ~ransmiss on ca!~1es. rhis attraction o ~ th~
~olym~r to the sit~e o~ th~ ~ccumul~t~d, t:ot~d~n5ed wat~
tha~ has p~r~eated ~.hrougl~ the L~lsulat ~ on cau~q the ~ighly vi~Co~ls m~terial ~o ac~ muld~ at thc~ si~e, which ~f~c,tiv~ly 5~,0p.c; ~ur~;.h~r ~ ~ter ~apoRr ~enetrati~n (ar~
subs~:34ll~n~ ondensati~n) ~hJ:t~ugh the polyet:hylene insu' ation ~y ~. build ~p o~: 2:1 inta~n~l ~o~n~e~-pressur~, w~i c!~ h~s ~ e~ect or st~ pi~ th~ above-~es.crlbed .reeing ph~oom~non ~hic~ wo~1ld ~therwise have occu-r~ d from th~ a~:c~ t~ ~n o~ ~ddit~ ona~ w~te~
The present invention therefore takes advantage of the presence of the accumulated, condensed water inside the pol'yethylene to solve the treeing problem. It does so by a fundamental change in the manner in which the problem is being 5 attacked, e.g., by providing a cable including a filling compound which, rather than functioning to exclude water or to absorb water in the manner of all known prior art cables, recognizes that the water will inevitably enter the cable as a vapor and, w hen it does, takes advantage of its presence to develop a counter 10 pressure barrier, thereby preventing further accumulation of condensed water at that site and thereby preventing treeing.
The water absorbent polymers which are suitable for use in connection with the filling compounds of the cable of the present invc ntion are those with a backbone having pendent ionic groups 15 attached to the polymeric chain, and are preferably polymers of non-naturally occurring monomers so as to be less susceptible to bacterial degradation. The ionic groups can be carbo l~ylate, sulfate, phosphate, sulfonate, phosphonate, ammonia or any otlher groups which become charged on exposure to water, 2 0 polycarboxylates being preferred. The preferred carboxylate polymers are those made from oc, 13-ethylenically unsaturated mono-and dicarboxylic acids and/or anhydrides such as propenoic acids, oc-methyl-propenoic acids, J3-methylpropenoic acids, maleic acicls, fumaric acids and the respective maleic and fumaric 2 5 anh ydrides. Particular success has been achieved using polymers of 2-propenoate, commonly referred to as polyacrylic acid or propenoic acid, and its derivatives, the anionic carboxylate groups of which, when exposed to aqueous conditions, yield a strongly negative charge along the polymer chain. The salt form of these 3 0 polymers can be used with a variety of ions including, but not limited to, alkali metal ions such as lithium, sodium, potassium or alkali earth metals such as magnesium, calcium, strontium, barium, zinc or aluminum. The salt used depends on the valency of the anionic group attached to the polymeric backbone.
35 Polymers of such polyacrylic acid derivatives are available from a numlber of sources, including Dow Chemical Corp., Stockhausen, Inc., and Hoechst Celanese Chemicals.
,h-iLIlOl~~~rc~ rt~ V~ r ;~ rb~,n~ y~ sll~c:
l y ~- a . ~)c ~ y l ;~ c', ,l ~ o l ~ l [ ~ y ~ s ll ~, v i ~ ) ll i C
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l n~ c ~ t i~i 2 l ~ c; ~ l z ~ t~ ,s r l-t':~c;~o~ r ~ t~c~ ~'ycoi, ~ t~
,~",f;'l~ ; r~f! t~ol~ln~r:~ ~f ~i~c~.s~ ly~ r~ .sucl~ tarch c ryl-~nl ~ri lc ~ r~ y~ ! 7 ~ s~ c~ lUI~';t ~ aliY-~s s~h a~ c~ri~ox~ c~lly! ~ lo.s~:, m:~y als~ nc uLili.~(l ro ;1~ v~; lt~tg~ In ~ lic a~ J~ t~ c~, s~ iym~rs I () .l.-e .;v~ lc rrt~ l'r;).L~ a~ (J,ai~ rc~:c~si~
~~rp Sllc h ~olyni~r.s ar~ ~;,L~ ir~ ulllb-:r t)~ p~tcn!s iricl~ldin "
i~;lL rot limiLt ~L l~, !il': w~;cr ;~ r~ oly~ttcr.~ .scril~r.d irl lhe .Yir,J ,~ cr.~ lit~
~." ..S . ~ J~S .
9,~ 2,173 !~ 'rl ~t~ iS~JS') 3,6~1 ,8 1~,;4,~1~3,~
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7" 4 ~j 7 y 3 ( ~ .S . .~ 7 1 " O ~'7 6, 0 ~S :~ Nu . .S 9 -3 7 ' (I ~, 1 7~15~44.6')0,97 ' ~~1 2 y 5, C~ ~3 'i 4 1 ~ f ~ 4 !~c.~ t11ciu~h r:~!1ym~r~ c' ~ sr .;r~l cr ll~lo~ c~.~.riv~ivc~
rLI::CIjG~l ;r~ In;lnn~ dC~,Cril)Cd ~VI1C~ ?e~SCC~ CI m~l~rix to 'o;r~ c L ~"~ S~e~ ;hc l,r~ c~ cl;~iu", s~ p~lyi~ls c ~ t;.-;1d~ r~ Or, jn~ )n~;~quc.~ y~ ~L~t~iyl~lcr~
on-n-1~u;cii y 1)cc~ll fill7J !llOIlO~:~'r.$ W~ J'~ So ~ Ut'il lc.s.c [~iod~gr~dai~lc (~)~;L ~ y ~r~ ~ ollccIL~ly l~f~.lLcd l~ a~ l-cill~, "noI~-J~IL~,t~da~ie'' ~ o~lcn()~ )i.s sp- ~;iri~;ati~ c prelc,rrc~i over 117~ r c~ al~t!J~ sc ~t~ri~ rs. I L~ l~1CC,y ~ ~ r l ~ .L- ~ i t .s L~I C I i V ;i ~ C .i L~ ' .'; L- ~ 'i n~c ~r~> r~ r~ ,r;~ ioll ovc~ io~t~ r:!l y~ s;
i r~l c ~ V i ~ j l t) l~ o ' y r~ v ~1 r UL~ yc;l.
Tl~ cr L~ Iy~ r i.s i~ r~ L~( c~ulld~ cil~ t~F ~llt~ L in~c~ ;Ll c~ nl~;L~ior;;;~_in~r, ~rom -l~t~ul s lo al~ y ~ci,~hL ;)f l~ riilin~
u n~ [~ t~ lJ rl d ~ ~lC ~ r ~ o n L~ i t: ;~ ! i) r ll o l y m ( r Il L i n, u ~1l s ~ 1 ;L~: ~a ~ y r~ u l ~ s ll ~ v ~ n ~ v~
C3~ iLiOlls ~nc!l~c'i~ CCL;~l~L~ions t~ y~ bo~T~ ~n~!s ~1 WO 96/36054 PCT/US9~/0~i732 tha~: range (hence the use of the word "about" in describing the range), concentrations of from about 10 to about l S ~o are pre:Ferred. As a general rule, if a cellulose polymer, or a polymer of a cellulose derivative, is used, it is preferred that higher S concentrations of polymer be used.
A number of compositions are used as a gel matrix. The mal:rix should provide a fairly uniform dispersal of the polymer in the gel. The viscosity of the gel is varied as described below deplending on a number of factors, including the method used to 10 introduce the filling compounds into the cable.
The gel matrices used in the filling compounds i nclude silicones, petroleum/hydrocarbon oils, high viscosity esters, glycols, polyglycols, olefins and fluorocarbons. Mixtures of polyalkylene glycols, polyalpha olefins and polyisobutylene may l S also be used, and such mixtures, along with hydrocarbon oils of various molecular weights, are presently preferred for use as gel matrices in the filling compounds of the cable of the present invention. The oil gel matrix is used to advanta ge in concentrations ranging from about 40 to about 95% by weight, 2 0 depending in part upon which non-heat melt producing thickener is utilized. The preferred concentrations, depending on the particular material, range from about 40 to about 85% by weight.
Gel matrices that are hydrophobic have a tendency l:o coat the polymer and essentially shield the polymer from the w ater. A
2 5 small amount of a hydrophilic substance is added to such hydrophobic gel matrices to counteract that tendency. The hydrophilic substance appears to provide a conduit for the water to contact the water reactive polymer, allowing the polymer to mi,grate to the moisture. A wide variety of materials is 3 0 appropriate for use as a hydrophilic substance in the filling compounds (particularly the second filling compound as de scribed below) of the cable of the present invention and can be used in percentages ranging from about 1 to about 15% by weight.
Particular success has been achieved with various straight and 3 5 branched chain mono, di-, ;3nd polyhydric alcohols including various polyalkylene glycols and mixture~; and derivatives thereof and various alkanols and mixtures and derivatives thereof. For example, ethylene glycol, hexylene glycol, and polyalkylene glycol W O 96/36054 PCTrUS95/05732 co-polymers randomly substituted with ethylene oxide and propylene oxide are used to advantage, as have isopropyl alcohol and 2-ethyl hexanol. Other materials appropriate for use as a hydrophilic substance in connection with the filling compounds of 5 the cable of the present invention include semiconducting materials as described more fully below, mono- and polyenoic unsaturated fatty acids and mixtures of fatty acids such as oleic acid, palmitoleic acid, linoleneic acid and linoleneic acids, as well as, for instance, tall oil, which includes oleic acid, and various 10 commercially available detergents and surfactants and mixtures of detergents and/or surfactants such as derivatives of sorbitan mono-9-octadecenoate polyoxy- 1 ,2-ethanediyl and 2,4,6,9-tetramethyl-5-decyn-4,7-diol .
Thickeners can be used to advantage in connection with the 15 gel matrices of the filling compounds of the cable of the present invention to achieve a desired non-heat melt property and viscosity. Suitable thickeners include those known in the art for thickening petroleum and fluorocarbon oils, gels, and greases such as waxes and petrolatums, and polyethylene microspheres and 2 0 styrene-ethylene butylene-styrene (S-EB-S) block polymers such as those available under the trademark KRATON (Shell Chemical Company), pyrogenic silica, organophilic clays such as bentonite and hectorite, soaps such as metal stearates, and ureas.
The amount of the thickener which is utilized depends upon 2 5 the viscosity desired, the particular fluid in which the thickener is used, and the thickener or thickeners used. Generally, the thickener is used in a concentration of from about 0.4 to about 24% of the gel composition by weight. For instance, if a self-activating organophilic clay such as BARAGEL 3000 (N.L.
3 0 Chemical, Inc.) is utilized as the thickener in, for instance, an oil gel matrix, the preferred concentration of thickener is between about 5 to about 10% by weight. However, such thickeners have been used successfully in concentrations ranging from about 4 to about 15%. If a petroleum hydrocarbon of, for instance, aliphatic 3 5 or napthenic paraffins, or a mixture of the two paraffins, is used as a fluid for thickening into a gel matrix, the amount of wax or petrolatum(s) added as a thickener preferably ranges *om about 0.4 to about 12%. The average molecular weight of the preferred p~aEr in~ n~e~: ~ro~n ~.00 ~ ~, lCC~, ~nd such par~ ; are u.5cd to prepare l illi~t~ compound~ wlth Visco~ s, dependin~ upon ~he proportion o~' thirken3r, o~ ~rom 5 to 200 ~ellt i s~.ok~s at 4 noc.
~ 'ar~icul~rly ~ el'erred a~ thi~eners c~,ompris,ed of a mi~ oP the v~ ri.,us subs~lnce~ ' is'ced aPoVc~. SUC]1 m.~xed th~ c}~n~rs may includc, ~or in~ance~ bt~tw~en about: ~ ~nd abo~l~ ;a~ (tot~i ~,7elg~.~ c~ ~he gel compo~ition3 o~ ~n cr~r~pi;ili~ y such as, benton-~e, bGtwaer~ CU'' 2.~ d -:: about 1~% ~t ota , w~ish~, of ~i~x 3r petrol~ur~,between a~o~t 0.~ 2.nd abo~ .81~ ~total weiyl~ o~ pyrog~:nit~ s~ 2, anti between ~bo~1,, 0.4 an~ abo~lt 18~ (~o~al wf~i~h~) of ethylane to~ poly~hyl~ne! r.;icrcis~heres o~ s-F:s-s bloc~; 201yr~e~.
1~h ~ Cil' i;l~ compo~;nt~s oE the c~ble of th2 ?re,~nt lnYen~i~n are ~a_ ied ?'S to ~esire~d v~ sc05ity ar~i ~equired by manu~ tu~ requireme~ts; I~ ic, generally preferred l~h2t t~e ~-' scos i-;y ran~ of the ~ e . ~om 2bout 2 centl.st~kes l O 0 ~ C t~ about ~ t,~, o o o ccnti ~t~okes .lt 4 0 O C . ~h~
~siscos ~y t~l7 the co~positlcn ic a ~att~r o~ choic~: ~or ~h~
s~rvic~ desired an~ i5 n~t intend~d i-~ be l~mit d ~y the ~peci. ~ cati~n of this pr6~;~ntl~ pre~e~rred vi~cos.ity ~ ge .
'"h~ ~r~c~inc p~ a~rap~s ~escribe a ~illing ccn~pound for ~il ling the sp~ce inside the o-l~er-mo5 pGl~thylen.? jackçt, cr shea'~h, and o~ ;ld~ I t~ outer-mc:st metal~ .c or pl~sti~, s~.ield a~ n~ the conduc~orts~ c~ the cable of tll~ present i.~ven~ion, ref erred to hc~l-ein as the ~-st ~ Ll Lng compollnd. ~o m~k~: t~e secc~nd ~illing ~c~po~Ind ~or use in th~ ~a}~le o~ tlle present inver~ion conc~ ting or semi-conduc~tin~ a mate~ l is added to the m~lerial us~d ~or ~he f'irst ~illin~ c:cmpound which imp.~rt~
conductlng prcpertias to the m~teri~L. l'hUS, the s~cond ~illing compoutld has con~lc~ln~ propert.~es. The se~ond ihg co~p~nd is use.d to ~ the spac~ bet~een, around and o~er ~.e conduc~o~ an~ side o~ the c;uter~ st -. CA 02220113 1997-11-04 ~n~talL ic G~- pla~tic s~ i~lcl, or in tht~ le whioh l~lut~ a~' ~ipla ~tr~lt~cd ccl~du~tor~ Q ~econ~ f illing compound 1 i1ls both th~ spaces ~twe~n et~ detl con~ Lc~ors~
~nd ~ .c;p~c:~ ou~ idc O.c th~ n~ r c;~nductors an~
id~ tr~e outor-mo~t ~hie~cl.
~ UC"I t,ondu~t ing ;~ n~uc:tin~ ~t;erials irlclude carban black, ~raphi~e, sili~a, d~cXld~ 3 varioue ~p~5 o~ c~y a~ Xnowll in t~.e zlrt.
Als~ nclu~G~d withir~ the scop~ ~ t.his invention ~ ~ such ~ateria~ a~IU~c)ll~ e;~lt: solutions, pre~era~ly hallàe, hydroxid~, c~bcna~e, bicar~on~te, nitrit~ .te, rat~, ~ha~Pn ~ ~C
....
~a -.trld r~}lo~yh,l~e s~lt~ Or ~odium, ,~otas~-ium, ca:!cium, r~ nesi-lm, ~;tanga~ese, i~tt, ~nd coppe~ rt~cu~r. ly E~re~rred ~ clutions o~ ma~n~siu~l carbonat~, m~g:l~S:iu~
c:,bLoride, ~ gnesium ~ lfa~., cJnd ~agnes~ pho~p~,~t:~ ~nd ~-ialt~ of so~ium ~n~ c~lci,um ,uch ~s scd_u~ and ~cilcium ~::hlori~3e, ~odi~l~ ;3nd c~.~ci.~;n e~r~at~, ~odium ~ica~bon~t~
~odillm ace~te, sod um sill~a~, so~ium ci~ral ~, soditlm and calci~m fluo~idc:, sodi~ lurosili~a~, sodlum phosph2lt~
~nd ~od_u~n a~d caîclum hydroxid~. The amour~t Or c:~nducting .. . or ~ conr3~loti~nq r,l.~t~rial .~ ed into the second fi.ll_n~
compo-~ild of ~h~ c~ c ~ p~es~n~ inv~nti on varie~
dependirlr; upon th6 part u' ~r ~na~éri~l use,d, the materic~1 ~s~d a~; th~ oil co~pon~r~t of the 'i1Ling cotnpour~d, and ~he c~nd~iVc pro~ertie~ expecte~ arom ~h~ operating p~1ram~ers of _he c~ble. I~hQ ~c~rld~ting or serni-cond~cti terial i ~ene~ally used in .~ weight to w~ight r~t.io of fr~m ahout 15 t~ ' S0 p~r~s to ~bout iOO pa~ts of thl3 oil c,cmpon¢nt 2~ ~he g~l ~natri x .
In i~dAitio~ to the ~at~r absorbin~ properti~5 o ~lLe fillin~ compou~d~ cf th~ c~ble of ~ch~a pr~se3~t lnv~n~icn ~ the ~ cc~spour.~s are su~:h cLS to ~re '' 'u.nction o~ not r~lo~in~ zt ~empcc~tur~: o~ GOO~C and abcl~e.
'~hu;" ~he f ~ ompound~ oL the present inven1:io~l are a~ o wlth~and temper~tures such ~ hose ercounte~ed cLS
a ~esult o~' ~ol~r ~a~nin~ and~or ~uring heavy loads on the po~er t~an~mission line withcut so~1.ch~.n~ and withcut a ~rop in vis~;osi~cy tha~ i5 SC~ w ~}lat the ~illing compound ~lows lengthwis~ in the ~bl~ (~.There there is/are low poi.n~s in the cabie~ or ~v~n à" jpc ~ut o~ tha cable~
l'h~ ~o.~lo~ing ar~ exclmples of ~~irst ~nd second fi ' ling c~omp~nds ~pproprial~e ~o~ ~s~ in th~ cable of the present int~er3tioll. r~h~ exan~pl~s o~ i~il lir~g compounds p, l~pa~ed in Accorc~an~e -~ith the inv~ntion are hot i~tcnded ~o limi~ the ~scope o~ ~he 1nvention and are instead il~' u~rativ~ rompounds used to pr~c~ic~ the inven'cion.
, O
EXAMI~I,I. 1 7~ ~irst s llin~ Compoun~ W~5 p~ep~rcq u.sin~ ~O
parts by wei~h~; polyi~obu~:yl enR oii (~no~ ~NDOPGL 1,-100), 4 l/~ pa--tE; by w~ t polyalp.h~ olL~Fin, and one p~rt by w~iah~ polyalkyl~n~ ~lycol ~ol i n C~eraical C~p . POI,Y-G
~150). ~ol~j~alkyl~l~e ~'y~ 15 a ran~o:n copoly~er with 7~5~
c~ yl2ne oxide and c.5~ prop~ c~r su}~:~titutior~, with an a~/e_aq~ t-.olec~ r weight of ~rom 1 Oa W O 961'36054 PCTrU'~95/05732 12,()00 to 15,000 and a hydroxyl number between 5 to l 0 mgs KOH per gram. The polyisobutylene has a viscosity ASTM D-445 38~C. of 210-227 and the viscosity index ASTM D-567 is 95. The polyalpha olefin used was a long chain polyalpha olefin S,HF -61 5 manu~actured by Mobil which had a viscosity ASTM D-445 AT
~! 38~C of 30.5 and a viscosity index ASTM D-2270 of 132. The pol~yalpha olefins which are used, as exemplified by the S;HF~61 Mo bil product, are typically hydrocarbons with a mo].ecular weight from 200 to 800. The SHF-61 product is an oligomer of 1 -1 0 decene. The satisfactory viscosity range of the polyalpha olefins is frorn 2 centistokes at 100~C. to 100 centistokes at 100~C.
Twelve parts of the resulting mixture was mixed wil h one parl: of pyrogenic silica as a thickener. The resulting gel matrix was blended two parts by weight gel to one part by weight of the 1 5 water absorbent polymer in the form of the partial sodium salt of crosslinked polypropenoic acid, referred to herein as 2-pol~ypropenoate (Dow Chemical Co.). Essentially the same results have been achieved using an identical filling compound inc,luding the polyacrylic acid sold under the brand name FAVOE~ C96 2 0 (Stockhausen, Inc., Greensboro, N.C.). When tested in accorda;nce with ASTM D 150 procedures, the composition was characteri.zed as having a dielectric constant of less than 2.3 and a dissipation faclor of about 0.01, and when tested in accordance with ASTM
D2';7, volume resistivity was about 4.99 x 1012. The composition 25 did not melt when heated to 200~C and had a water response time of under 12 minutes.
A first filling compound for use in the cable of the present invention was prepared in the manner ~escribed in Example 1 3 0 and having the following contents (parts by weight):
DRAKEOL 34 (Penreco Corp.) 6 1 0 REOMET 39 (Ciba-Geigy Corp.) 2.5 BENTONE 24 (NL Chemicals., Inc.) 50 Acetone 10 3 5 AEROSIL R74 (Degussa Corp.) 20 FAVOR C96 (Stockhausen, Inc.) 150 MICROTHENE FA640 (Quantum Chemicals Corp.) 157.5 When tested in accordance with the procedures described in Example 3, the composition was characterized as having a dielectric constant of 2.12, volume resistivity of 5.91 x 10l2, and a dissipation factor of 0.01. The composition did not melt when heated to 200~C and had a water response time under 10 minutes.
Polyesters have also been used to prepare a first filling compound for use in the cable of the present invention. The polyesters ranged in molecular weight from 300 to 800 and have viscosities from 25 to 1 00 centistokes at 40~C . The polyesters were mixed about 10 to 30% of the polymer. The polyesters which have been utilized are esters of trimethylol propane, pentaerythritol and triallyl mellitate, and when tested, produce results similar to those of the compound of Example 2.
A second filling compound for use in the cable of the present invention is made by mixing the following (all percentages by weight):
70% oil-rubber blend (see below) 2 0 8% CABLOC 800SF (Stockhausen) 5% BARAGEL 3000 (Rheox) 15% 665 Grade talc (Montana Talc Company) 2% PRINTEX XE 2 Extra-Conductive Carbon Black (Degussa Corp.) 2 5 The oil-rubber blend is made up of the following (percentages by weight):
94.77% N1500 (Pennzoil) 3.3% KRATON 1701 (Shell Chemical Co.) 1.58% IRGANOX 1035 (Ciba-Geigy Corp.) 3 0 0.35% IRGAMET 36 (Ciba-Geigy Corp.) The second filling compound absorbed water in 1 1-12 minutes, had a dielectric constant greater than 3.67, volume resistivity less than 5 x 106, cone penetration of 152, and 0.8% oil separation after 24 hours at 80~C.
A second filling compound for use in the cable of the present invention is made by mixing the following (all percentages by weight):
WO 96;/36054 PCTI~S95105732 82% oil-rubber blend (see Example 4) 5% AEROSIL R74 (Degussa Corp.) 8% FAVOR C96 (Stockhausen, Inc.) 5~o aqueous solution of mixed metal salts 5 The mixed metal salt solution was comprised of water and several salts of calcium, sodium and magnesium, the concentration of all such salts aggregating to less than 1 ~o. When tested as described abc~ve, the dielectric constant of the compound was 3.22, dis~iipation factor was .0321, and volume resistivity was 71.89 x 10 10~;.
A second filling compound for use in the cable of the present invention is made by mixing the following (all percentages by weiight):
1 5 77.5% oil-rubber blend (see Example 4) 4.5% AEROSIL R74 (Degussa Corp.) 8% FAVOR 900 series polymer (Stockhausen, Inc.) 10% aqueous solution of mixed metal salts (see Example S) 2 0 When tested as described above, the dielectric constant of the compound was 3.78, dissipation factor was .0356, and ~.~olume resistivity was 28.7 x 105.
A second filling compound for use in the cable of the present 2 5 inv~ention is made by mixing the following (all percentages by wei ght):
71.03 % N 1500 (Pennzoil) 2.47% KRATON 1702 (Shell Chemical Co.) 1.18% IRGANOX 1035 (Ciba-Geigy Corp.
1.31% IRGAMET 36 (Ciba-Geigy Corp.) 4% AEROSIL 200 (Degussa Corp.) 8% FAVOR 900 series polymer (Stockhausen, Inc.) 2% polyglycol 10% aqueous solution of mixed salts 3 5 (see Example 5) When tested as described above, the dielectric constant of the connpound was 6.95, dissipation factor was .2766, and volume CA 02220ll3 l997-ll-04 r ~si~'civl~:y w.~=, 2, ~3 ~ )6. W~t3r ,I~;crp.ion t~i:nes; were a~ s ~ s .
t * 1~ * ~ 1.
R~ rrin5~ no~ to t:he f i~ re~, 5howr. in sche~nat:ic ~-~p~esen'~ )n ic: a ~hod ancl ~pp,~a~us fcr ,na~i~g a powe~
~,~ansm~ Jl cable ir.cllldi~g the first ~nd ~econd fi.lling coTrpound~ o~ th~ p~eC;e~t inv~nt;1 or~ such as the cable shcwn Ln ~ u~c z. Such a cabl~ icat~d ~enPrall~ a~
-ef~encP r~u~ner~i~ 10 i~ ~-ompr~cd o~ a plurall~y o~ wir~s, cr c~du~~r~, 12 cont~in~l in ~ ~2ckP'c 1~ i n ~he ~orm of --~ a poly~neric, ~he~th as k~lown in -~ ar~, ~hich may be ~ormed y po.l ye ._~v I en~ .
To ;nek~ ~he cabl? ~ O, t;hc~ conducto3; ;Z are ~wn thro~h ~ I illir.~ ~~t~arlr6r 16 rf.o~nt~l ir. a filling head s~ ~nd 12 ln whic~l thc se-~on~ c-:~tnpound 23 o~- the c~bl~: o~ tt-e pre~ent irlvention i~ e~ruded on to the cor.~uc or~ compri~ir.~ t;3e csi~ c~rc. Five cond~lc~ o:~s 1G ~e ~how~- erlt~in~3 ~ch o~ fi~,e ~illing chambers lG in Fi.~,ure 1 . 'L'he I i ~ ling cha~b~_ s J.O n~ r ~ n~ char:l~er ~;t~ld 1~ a-e ~.cu~tP~ on the sha~.s ~2 of ~nd ~scil' a~ed by an osc~ lla~,in$ ~ c~lne 24 cf ~! ' ype Xnown in th~ ustry, and th~ f:ive co.sductors ex~ing fllling cl~m~ers 1~ a~e pas~d th_;~ugh a si~inc inse~ ~not sho-.n) ~ ow:~ in the a~.t ~o that ~h~e am~Ln~ o f second ~illinq c~rr.pound e.Y~,~uded in th~
5~2C2 bet~tre~n and on to each con~Lc~. 12 is standardi.sea~.
A~ thc c~nduc~orc, 12 ~it os~iLl~.inq machine 24, ~chey ar-e br~ h~ toy~ther ~d a convent.icn~ e~ conductive l.ay~r 2~ (~hic;h ~;~y be a pl~stic lnaterial) i~ wrapped or exir-uded OVi~ L' i Ll in~ compoun~ at ~ t i l l ~ n~ s~tion ~;hown scher~atic~lly (becau~e it 1~ know1~ int h~ art) a~ ref~3nc~
r~ume~1 7.~, the l~ye_ 26 fc3-mi~g a conductor s~~esS ~ntrol ~ayer~ Thc l;~y~r ~6 is then ~nci.~cled by a laye~
polymc~ s~lati~:~ 30 ~u~h ~s poly2-~hyle~ ~hich is extruded ~ extrLlder s.ati.on 3Z. ~rhe second fillin~
colr.pound i~: located in thY spa~d Det-~eert the ccnduct~rs 12, ~nd ~lsa be'citeen ~he conduc~crs 12 and the layer ~
.
CA 02220ll3 l997-ll-04 irl~,uli~tion .~o. ~ se~nd pla~ 5.re55 cont;ol laycr 3~
.n~y al~G 1~ x~;rudec~ ~/c~r the l~ye~ cf insula~ion ~ at:
anoth~r ~t~lt' on ~c~ lso ~own st:h~ms~t lcally~
A me~al shield 3~ the losn~ of ~ ccpper ~r all:;inillm ~;-pe c~, s~ri,~, is then helic:;~lLy wound aroun~ the ~undie~, ins-;_a~Gd, ar~d _illed con~ tor~ at st~tion ~0 in a ma~nc~ kno-~rl in the in~ust~ . The sni~ldad c~ndl~tors ~l-e ~ n d~w~ in~o ~ second ri~ ~ i r~ head 42 ha~ g a ch~b~r si~i.la~ ~o ~.n6 chL~kcr~ ~ 6 mounted ~herein .~sr e~:trudln~ the ~i~s ~ f i'~ lin~ c ~m~pcl~n~ ~ ~ o~r and ~und ~:h~
bunc~lc~c~, insul~.t~d, t'~. ! Icd ~nd shielaed condu~tor~ ~2.
Upon exi ~ i~t; ~ ll il-~g l~ad ~.Z, th~ c~ble ifi th~n 2r~c;ircl c~
by a j a~,}cer. lq by o~Y~rusion o~ a pol~eri - material at ex~_ude.r ~t~tion 46.
The sec~d ril 11~$ com,pound ;i~.t) of thc ca~lc~ ~l the p~ cnt i~v~n _io~ is ~ p~d into t~c f~il l i~g cha~bers 16 at 2pproxima~el~,~ ~oom tamper~ture a~d i5 maintairled under p~es~ure _o as ~o ~;~ci. I lt~t~ e~t~ usi on orl ~o th~ c~nd~ctors 12 . A si;~ilar ar~s~ment an~ c~hditc~ 0~15 i~C used in th~
~e~o~d ~illing he~ci ~ or extru~ on OL ' he fir.~t Ci.l lin~
coinpound 4 4,
The present invention is directed to that same problem and improves on the approach taken on the patent documents listed in 3 0 the preceding paragraph. Specifically, U.S. Patent No. 4,703,132 describes a filling compound, and a cable containing that compound, which comprises a low molecular weight rubber adrnixed with a sprinkling of fine particles of a material applied over the filling compound which swells when it absorbs water and 3 5 which is said to be soft enough to be applied to the conductor wil:hout the use of extrusion equipment. As set out in that pal:ent, the filling compound is applied to the conductor wires as t!hey are brought together in concentric layers and then, as the wires ha ving the filling compound therearound are brought together, the outer surface of the conductor bundle is covered by extrusion with a conventional semiconducting stress control layer which completely fills the interstices in the outer layer of wires. A
semiconducting rubber filled tape is then applied, followed by a layer of extruded insulation, and other layers all as described in more detail in column 2 of that patent.
As the filling compound described in Patent No. 4,703,132 is applied over a layer of wires, the filling compound is exposed to fine particles of a water swellable material by passing the layer of 1 0 wires having the filling compound applied thereto through a chamber containing such particles as they are being blown about in such a manner that the particles adhere to the exposed filling compound. That patent (in column 3) also suggests that the water swellable powder could be mixed with the filling compound and 1 5 then applied to the conductor(s) in that same manner. However, that patent gives no instruction as to how to make that mixture or how a mixture of powder and filling material would function to solve the aforementioned-mentioned problem in light of the highly hydrophobic character of the filling compound. In effect, 2 0 the filling compound is so hydrophobic that it prevents interaction between the powdered water absorber and the water.
Although the invention described in that reference is stated to have been made for the purpose of overcoming the above-characterized treeing problem, that it did not do so is made clear 2 5 by the existence of U.S. Patent No. 5,010,20g, which issued to the same party as U.S . Patent No. 4,703,132, and which addresses this same treeing problem. Patent No. 5,010,209 discloses the use of the same filling compound and water swellable material, but with so-called helical elongated metal elements disposed around the 3 0 insulation shield, each of the metal elements having particles of a water swellable material at least at the adj acent edges of the metal elements. Just as Patent No. 4,703,132 did not provide the solution to the treeing problem, No. 5,010,209 did not provide the solution either.
3 5 The manufacture of cable such as the cable described in U.S.
Patent No. 4,703,132 is also problematical. When the polyethylene sheath, or jacket, of such cable is extruded onto the conductors that have been coated with the filling compound, it is a. a te~per~ u~ which i5 hig!~ enouc~ o m~.lt ~he f'.~ 4 ~omp~und ~u~ rk a~ o~t r~ w~e~- s~el~ m~ rial d~sc:~ b~ tl~. Patent) ~plif~d to ~he ou~iAe o~ th~
concIL;c' o~. C~nJequen~ly, it i..~ ~cc~.~;sary either to t~k~
~eps ~uriI~g m~nufactu~ pr~ ve tk~ I i.l~ ng c:c~m~ound ~'~ om sxpo~u~ o ~ pe; a~ c_ o~ c ~il1in~ ~omE~ouncl i~
nccd~d whi~h dcic~5 no~ mel~.
Ac;ccrding ' o I his ~ r.~ent lon ~h~e is pro~rided ~L
pc~we~ n~ -sion cc.ble C~mFri;ai~g at lza5t OrlR c;ent;ral ~ond~cto~ ? aye~ o~ s~lat~on ~o~lnd ~LC~ cond~c~:or(~;
a m~tallic ~n~lor ~ st:ic 5~1if~ ove~ the 1aye~ o~
in~laticn, a polynerl~ ;,h2~h ~r~und 'hG shioldi ~i ~i.rst f illin~ -om.pG~nd l~c~:c~ ~r~c~c~n S.~ polynl~ri~ 3t~ !th znd s~id ~ iel~ d c secoi1d ~ nq compou3ld ~ ocated bet-~een s~id centra; c~olndu~~-.r ~nd ~ yer c,f ~n~ul~iGn wh~-ei~
the f i -~t, ~ c~ c~pc~.~r.~ co::lpris~ a dielect-ic g~l h~-~ing a wate~ ac~.iv~ ~a~yme?~ ~lisper=,ed ~h~rein and said s~con~ fil~ ing co:~po~nd con~prlses ~ ~el ILa\~ing ~ w~Lte~
reacti~ po3.ymcr ar.~ a cor,u~.ctirlCJ o~ ~emi-concluc~: ng r.,~er~ pers~d ~h~rei~.
Pr~.f cra~iy the c,~le c:o~r.prises ~ plural .lty o*
cen~ral conduc~rs ancl ~as second ~illincs ~o~pG~md: o~t~cl in 1:he spaces ber~ee~ ~h~ c~ndu~o~ sel cf ~he rlrst ~i' ling ~o~npound and o~ th~ s~~cn~ fill_n~ ccmpolln~ r.ay con~prise ~n oil ~ a thi~Xener.
Pr~r~bly th~ sh~.'d i~, me~ d the po:Lymer~o sheath i~ of polv~thylene.
Tlle i r.v~ntl on ~1 so p~ov ~' des a m6thod o~
~r.anu~acturing ~ p~ n~is;.ion cable co~..prising th2 st~ps o~ m~king fi.st aTl~ se~ li.n~ compoun~ls, ~h~
first ~ compourld ~ein~ ~d~ by dispers ~ ng a tJa~_er-a~sor~ing p~ly~ner in a non-h.o;at-melting gel matrix, ,~nd the second f illing c~npound beinq ~3ade ~y ~i~p~rsin~ w~ter-a~sor~c,lt polymz. ~ncl ~ ~oon~i-Actin~J Or .~ c~nducti n¢~
~te~ial in ~ no~.-nc~ melt_nq ~e~ ri.x, ~o~cin~ t:h6 s.~ncl ~ g _¢~n~pour.d in o a ~h~ r under pressur.e ~nd r.~ovi~ one or ~.o~c o onduc:tors ~hrou~;h t~ press~ ;ed r~¢~ ~ ontraU~ ln ~h~ ch;1~nb~l: ~y p~s~irLg the conduc~:or~s) thro~h entry and ¢Xit op~nin~3 in ~l~e ~ha~bla.r so t~ t t;~c~
sc~c~ond t-~ . ~ing compollnd is ~ n~ or~ t~ ~he corlducL;~r(~;), and~o~ int~ th~ cc~ bct~e~n the ~ond~ct3rs ~pp~ yi.ng A~su'ation ~h=~to and ,. metall~c ~lnd/or pIastic ~hield ~Lnd an ou~e.~ ~ol~ ric .~-.hc~,i..h an~ n~ ~ he sp~ce outs:ld~ o~
- the s~,ie' d ,~ n~;iclc Gf '~he outcr po.l ym-ri c sheat~l witn the f i r~ n~ compo~rl~.
' t r.as ~cen ~o~n~ t.~a~ pt e~'crred ~npocimen~s o~ th~
in~cr.t~cn pl-ov~le ~ po~r ~a~smi ~ion ca}~le that d~es not s~4;er ~ rom '_he a ,-ye~ ur-s~lYed problem o~ mt~ist~t~ d~c:~d dt~gra~ion in t~,~ per~ornl~.nce o~ po~lle-- tr~ns~issior~ cable insula~i sn. ~rh~ pref~r~ed ~:ablta is fillc~ With a colnpcsitio~ whic~ does nct ~nt l ~ at the ter..p~ratur2s a~
~h .ch i,~lsul~ition i~ x- rud~ nto r~hc! cable. A pre~'rerr.ed embodt~el~ o~ th~ in-~en~:ion compri~es a cablt~ h~vl~g a CO~t-~
ca~r.p. ised of' one or :rt~ ~ condu~;tors ~ ~ 1 ayer of i nsu Latior ~ro~nd th~ c:s2~dut;to~ls), a mt~t~lliG ~nd/or plas~ic s~hield ~o,,nd the )~~ulat-~on laye, ~ pc~ it- sl~ h which i5 ex~r~lded t~ver tne skicl~, c,r.d 4WO ~illin~ comvoun~s.. '~hc =pC cP b~t-rJs~n the ~olyme~i~ she~h ~.nd t~e c~t~id~ o~ t he rr,ct.a~1ic or pl~ s!lielt i~ ~ille~ witl: c~ ~,r~it ~.ill..~g cGmpound, w~ich is co~pri5ec~ cf a non-hcat me.~tillg, d.ielec:~ric ~.,e1 r~l~tr~ x ..~nd ~ w;3 t~r a~scr~in~ poly~ner., 1:he er ~so..~ing po' ym~r beir.g c~ ~ h~ tyF:~ kno~n as ~ ~uper a.hsor~r ~ n~ch i~; c~prisk~ of ~ polyme~ic bzck~one ha~ g p~rLdan~ io~Lc sroups n~h~ c~s t~r~twc~3n the conductor (s~, and the space }~tween th~ csnductor (s~ ~nd ~h~ innerr~ost ~eta~ lic or pl~s,l~: shleld, is fillc~ h t~e ~-econà
f.ill ins cc~Lpclund, ~1 ~ ch is comprised o~ ~enerally ~he ~;3,~
m~e~ia.~s ~s compr~ ~e the ~lr~t filling com~po~lr;d, speci~ically/ z nsn-hea~ elti;~ 1 rnatr~x havtn~ a ~er =
a~t~r~ ,t~ly~e~ di~p~rs~d ~ r~.in, alld wl~ic.'l ~lso irlcludeS ~ t;~nt~ic~in~ or ~emi-~,orldl~ct~ .at~ridl.
~ rh~ ~inV~n~ o~ hC~ dBscrib~d by way o~
~x-,~r..plc t~ e~t~renc~ r,~ t~e t~r~in~ n whic}~:
F~GUI~ 1 is d ~r;o~h~ tic Lepres~nta.ion cf a metnod and app~ra.u~ f or m~ki~tg a ~ow~l ~ransmisslon ca~l~
inC~ di~ lC~ gc!~ composition o~ ~ he present lnv~ntiorl, ~nd FIC.~!~E 2. is a cu~ ~sway pers~ect~ve ~ie~ of a power oabl~3 typ~ ~Jkich L~ dc ~.th 'ch~ appar~:us or ~igurt~ 1.
.~ will b~. d~srribed .ht i~vt3ntion provi~es 3 cable r:~vin~c r~ ins Co:~pcuhd~ ~ach ~ ing co;;~po~nd compr~ s a ~el having ~ whter _~ac;tiv~: pclymer dispersed l:here i n. ~rhc ~cconc~ or the t~o f i lling t;o;npoundc ~da ~ ~ iona ! ly co~pr i ses ~ sem -.-o~d~lctihg or ~:ond~cti~g a t ~
T~ g~.~ oS both tht~ fir~t: anG second fill~ ng co~npoun~s ol the ca'~l~ of .he p-e~nt i~vention r likt~ th~t o~ prior l i.lling compounds for .x.~h c:~le, is characte~is~t~
~s b~ nt~ hvd-ophobic and ~he~-efo~ e provides an ini~
bar_ ie.r r.o Ihe sp ead and/ or r~.ig~tion o~ we,te:r .in the ~a~ t? . ~Gw~ver, w~en in the ~r~cnce o~' w~ter, ~he f ine powder~ ;c poiy~ner gr~ ;es in ~he sel of t~e ~able of the refer.-ed embodimants o. ~,he pres~n~ lnvent' on ~ravel to ~he w~ di~cerlt the ~el ~atrix. l~his er~e~ct ~ s ~a~ilitc~ted by the addition o~ 2 hy~roF~illic substan~e to the gel, which ~ llows ~he relecLse cf th~ water absor~nt ~oly~;~er tO ~ee~; out the wa~er ~lue to the electroche~ ~al ,~ttr3ction ~:3tw~e,n tlle w~te~ ~so!ecules an¢~ ~he ionic ~xc~Ess ~f the wat~r a~sor~ent: E~olylnor. once th~3 water is c~nt~:ted b~ the polymer that i ;~ re~ eafie~d fr~m the ~al, a highly vlsc~c~u5 mat~ria1 for3~s as él r¢sult o~ l~inding of the -~a~er by the polymer w~ich i 5 ~ TI incapable o~ fl~id rnove,~ent un~er ~he hyd~ os~tatic pr~ssures n~rmally 6,xerte~l on pow~r ~ransmiss on ca!~1es. rhis attraction o ~ th~
~olym~r to the sit~e o~ th~ ~ccumul~t~d, t:ot~d~n5ed wat~
tha~ has p~r~eated ~.hrougl~ the L~lsulat ~ on cau~q the ~ighly vi~Co~ls m~terial ~o ac~ muld~ at thc~ si~e, which ~f~c,tiv~ly 5~,0p.c; ~ur~;.h~r ~ ~ter ~apoRr ~enetrati~n (ar~
subs~:34ll~n~ ondensati~n) ~hJ:t~ugh the polyet:hylene insu' ation ~y ~. build ~p o~: 2:1 inta~n~l ~o~n~e~-pressur~, w~i c!~ h~s ~ e~ect or st~ pi~ th~ above-~es.crlbed .reeing ph~oom~non ~hic~ wo~1ld ~therwise have occu-r~ d from th~ a~:c~ t~ ~n o~ ~ddit~ ona~ w~te~
The present invention therefore takes advantage of the presence of the accumulated, condensed water inside the pol'yethylene to solve the treeing problem. It does so by a fundamental change in the manner in which the problem is being 5 attacked, e.g., by providing a cable including a filling compound which, rather than functioning to exclude water or to absorb water in the manner of all known prior art cables, recognizes that the water will inevitably enter the cable as a vapor and, w hen it does, takes advantage of its presence to develop a counter 10 pressure barrier, thereby preventing further accumulation of condensed water at that site and thereby preventing treeing.
The water absorbent polymers which are suitable for use in connection with the filling compounds of the cable of the present invc ntion are those with a backbone having pendent ionic groups 15 attached to the polymeric chain, and are preferably polymers of non-naturally occurring monomers so as to be less susceptible to bacterial degradation. The ionic groups can be carbo l~ylate, sulfate, phosphate, sulfonate, phosphonate, ammonia or any otlher groups which become charged on exposure to water, 2 0 polycarboxylates being preferred. The preferred carboxylate polymers are those made from oc, 13-ethylenically unsaturated mono-and dicarboxylic acids and/or anhydrides such as propenoic acids, oc-methyl-propenoic acids, J3-methylpropenoic acids, maleic acicls, fumaric acids and the respective maleic and fumaric 2 5 anh ydrides. Particular success has been achieved using polymers of 2-propenoate, commonly referred to as polyacrylic acid or propenoic acid, and its derivatives, the anionic carboxylate groups of which, when exposed to aqueous conditions, yield a strongly negative charge along the polymer chain. The salt form of these 3 0 polymers can be used with a variety of ions including, but not limited to, alkali metal ions such as lithium, sodium, potassium or alkali earth metals such as magnesium, calcium, strontium, barium, zinc or aluminum. The salt used depends on the valency of the anionic group attached to the polymeric backbone.
35 Polymers of such polyacrylic acid derivatives are available from a numlber of sources, including Dow Chemical Corp., Stockhausen, Inc., and Hoechst Celanese Chemicals.
,h-iLIlOl~~~rc~ rt~ V~ r ;~ rb~,n~ y~ sll~c:
l y ~- a . ~)c ~ y l ;~ c', ,l ~ o l ~ l [ ~ y ~ s ll ~, v i ~ ) ll i C
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l n~ c ~ t i~i 2 l ~ c; ~ l z ~ t~ ,s r l-t':~c;~o~ r ~ t~c~ ~'ycoi, ~ t~
,~",f;'l~ ; r~f! t~ol~ln~r:~ ~f ~i~c~.s~ ly~ r~ .sucl~ tarch c ryl-~nl ~ri lc ~ r~ y~ ! 7 ~ s~ c~ lUI~';t ~ aliY-~s s~h a~ c~ri~ox~ c~lly! ~ lo.s~:, m:~y als~ nc uLili.~(l ro ;1~ v~; lt~tg~ In ~ lic a~ J~ t~ c~, s~ iym~rs I () .l.-e .;v~ lc rrt~ l'r;).L~ a~ (J,ai~ rc~:c~si~
~~rp Sllc h ~olyni~r.s ar~ ~;,L~ ir~ ulllb-:r t)~ p~tcn!s iricl~ldin "
i~;lL rot limiLt ~L l~, !il': w~;cr ;~ r~ oly~ttcr.~ .scril~r.d irl lhe .Yir,J ,~ cr.~ lit~
~." ..S . ~ J~S .
9,~ 2,173 !~ 'rl ~t~ iS~JS') 3,6~1 ,8 1~,;4,~1~3,~
3t56.~"J~ 4~ J~r~,ncsc ~
7" 4 ~j 7 y 3 ( ~ .S . .~ 7 1 " O ~'7 6, 0 ~S :~ Nu . .S 9 -3 7 ' (I ~, 1 7~15~44.6')0,97 ' ~~1 2 y 5, C~ ~3 'i 4 1 ~ f ~ 4 !~c.~ t11ciu~h r:~!1ym~r~ c' ~ sr .;r~l cr ll~lo~ c~.~.riv~ivc~
rLI::CIjG~l ;r~ In;lnn~ dC~,Cril)Cd ~VI1C~ ?e~SCC~ CI m~l~rix to 'o;r~ c L ~"~ S~e~ ;hc l,r~ c~ cl;~iu", s~ p~lyi~ls c ~ t;.-;1d~ r~ Or, jn~ )n~;~quc.~ y~ ~L~t~iyl~lcr~
on-n-1~u;cii y 1)cc~ll fill7J !llOIlO~:~'r.$ W~ J'~ So ~ Ut'il lc.s.c [~iod~gr~dai~lc (~)~;L ~ y ~r~ ~ ollccIL~ly l~f~.lLcd l~ a~ l-cill~, "noI~-J~IL~,t~da~ie'' ~ o~lcn()~ )i.s sp- ~;iri~;ati~ c prelc,rrc~i over 117~ r c~ al~t!J~ sc ~t~ri~ rs. I L~ l~1CC,y ~ ~ r l ~ .L- ~ i t .s L~I C I i V ;i ~ C .i L~ ' .'; L- ~ 'i n~c ~r~> r~ r~ ,r;~ ioll ovc~ io~t~ r:!l y~ s;
i r~l c ~ V i ~ j l t) l~ o ' y r~ v ~1 r UL~ yc;l.
Tl~ cr L~ Iy~ r i.s i~ r~ L~( c~ulld~ cil~ t~F ~llt~ L in~c~ ;Ll c~ nl~;L~ior;;;~_in~r, ~rom -l~t~ul s lo al~ y ~ci,~hL ;)f l~ riilin~
u n~ [~ t~ lJ rl d ~ ~lC ~ r ~ o n L~ i t: ;~ ! i) r ll o l y m ( r Il L i n, u ~1l s ~ 1 ;L~: ~a ~ y r~ u l ~ s ll ~ v ~ n ~ v~
C3~ iLiOlls ~nc!l~c'i~ CCL;~l~L~ions t~ y~ bo~T~ ~n~!s ~1 WO 96/36054 PCT/US9~/0~i732 tha~: range (hence the use of the word "about" in describing the range), concentrations of from about 10 to about l S ~o are pre:Ferred. As a general rule, if a cellulose polymer, or a polymer of a cellulose derivative, is used, it is preferred that higher S concentrations of polymer be used.
A number of compositions are used as a gel matrix. The mal:rix should provide a fairly uniform dispersal of the polymer in the gel. The viscosity of the gel is varied as described below deplending on a number of factors, including the method used to 10 introduce the filling compounds into the cable.
The gel matrices used in the filling compounds i nclude silicones, petroleum/hydrocarbon oils, high viscosity esters, glycols, polyglycols, olefins and fluorocarbons. Mixtures of polyalkylene glycols, polyalpha olefins and polyisobutylene may l S also be used, and such mixtures, along with hydrocarbon oils of various molecular weights, are presently preferred for use as gel matrices in the filling compounds of the cable of the present invention. The oil gel matrix is used to advanta ge in concentrations ranging from about 40 to about 95% by weight, 2 0 depending in part upon which non-heat melt producing thickener is utilized. The preferred concentrations, depending on the particular material, range from about 40 to about 85% by weight.
Gel matrices that are hydrophobic have a tendency l:o coat the polymer and essentially shield the polymer from the w ater. A
2 5 small amount of a hydrophilic substance is added to such hydrophobic gel matrices to counteract that tendency. The hydrophilic substance appears to provide a conduit for the water to contact the water reactive polymer, allowing the polymer to mi,grate to the moisture. A wide variety of materials is 3 0 appropriate for use as a hydrophilic substance in the filling compounds (particularly the second filling compound as de scribed below) of the cable of the present invention and can be used in percentages ranging from about 1 to about 15% by weight.
Particular success has been achieved with various straight and 3 5 branched chain mono, di-, ;3nd polyhydric alcohols including various polyalkylene glycols and mixture~; and derivatives thereof and various alkanols and mixtures and derivatives thereof. For example, ethylene glycol, hexylene glycol, and polyalkylene glycol W O 96/36054 PCTrUS95/05732 co-polymers randomly substituted with ethylene oxide and propylene oxide are used to advantage, as have isopropyl alcohol and 2-ethyl hexanol. Other materials appropriate for use as a hydrophilic substance in connection with the filling compounds of 5 the cable of the present invention include semiconducting materials as described more fully below, mono- and polyenoic unsaturated fatty acids and mixtures of fatty acids such as oleic acid, palmitoleic acid, linoleneic acid and linoleneic acids, as well as, for instance, tall oil, which includes oleic acid, and various 10 commercially available detergents and surfactants and mixtures of detergents and/or surfactants such as derivatives of sorbitan mono-9-octadecenoate polyoxy- 1 ,2-ethanediyl and 2,4,6,9-tetramethyl-5-decyn-4,7-diol .
Thickeners can be used to advantage in connection with the 15 gel matrices of the filling compounds of the cable of the present invention to achieve a desired non-heat melt property and viscosity. Suitable thickeners include those known in the art for thickening petroleum and fluorocarbon oils, gels, and greases such as waxes and petrolatums, and polyethylene microspheres and 2 0 styrene-ethylene butylene-styrene (S-EB-S) block polymers such as those available under the trademark KRATON (Shell Chemical Company), pyrogenic silica, organophilic clays such as bentonite and hectorite, soaps such as metal stearates, and ureas.
The amount of the thickener which is utilized depends upon 2 5 the viscosity desired, the particular fluid in which the thickener is used, and the thickener or thickeners used. Generally, the thickener is used in a concentration of from about 0.4 to about 24% of the gel composition by weight. For instance, if a self-activating organophilic clay such as BARAGEL 3000 (N.L.
3 0 Chemical, Inc.) is utilized as the thickener in, for instance, an oil gel matrix, the preferred concentration of thickener is between about 5 to about 10% by weight. However, such thickeners have been used successfully in concentrations ranging from about 4 to about 15%. If a petroleum hydrocarbon of, for instance, aliphatic 3 5 or napthenic paraffins, or a mixture of the two paraffins, is used as a fluid for thickening into a gel matrix, the amount of wax or petrolatum(s) added as a thickener preferably ranges *om about 0.4 to about 12%. The average molecular weight of the preferred p~aEr in~ n~e~: ~ro~n ~.00 ~ ~, lCC~, ~nd such par~ ; are u.5cd to prepare l illi~t~ compound~ wlth Visco~ s, dependin~ upon ~he proportion o~' thirken3r, o~ ~rom 5 to 200 ~ellt i s~.ok~s at 4 noc.
~ 'ar~icul~rly ~ el'erred a~ thi~eners c~,ompris,ed of a mi~ oP the v~ ri.,us subs~lnce~ ' is'ced aPoVc~. SUC]1 m.~xed th~ c}~n~rs may includc, ~or in~ance~ bt~tw~en about: ~ ~nd abo~l~ ;a~ (tot~i ~,7elg~.~ c~ ~he gel compo~ition3 o~ ~n cr~r~pi;ili~ y such as, benton-~e, bGtwaer~ CU'' 2.~ d -:: about 1~% ~t ota , w~ish~, of ~i~x 3r petrol~ur~,between a~o~t 0.~ 2.nd abo~ .81~ ~total weiyl~ o~ pyrog~:nit~ s~ 2, anti between ~bo~1,, 0.4 an~ abo~lt 18~ (~o~al wf~i~h~) of ethylane to~ poly~hyl~ne! r.;icrcis~heres o~ s-F:s-s bloc~; 201yr~e~.
1~h ~ Cil' i;l~ compo~;nt~s oE the c~ble of th2 ?re,~nt lnYen~i~n are ~a_ ied ?'S to ~esire~d v~ sc05ity ar~i ~equired by manu~ tu~ requireme~ts; I~ ic, generally preferred l~h2t t~e ~-' scos i-;y ran~ of the ~ e . ~om 2bout 2 centl.st~kes l O 0 ~ C t~ about ~ t,~, o o o ccnti ~t~okes .lt 4 0 O C . ~h~
~siscos ~y t~l7 the co~positlcn ic a ~att~r o~ choic~: ~or ~h~
s~rvic~ desired an~ i5 n~t intend~d i-~ be l~mit d ~y the ~peci. ~ cati~n of this pr6~;~ntl~ pre~e~rred vi~cos.ity ~ ge .
'"h~ ~r~c~inc p~ a~rap~s ~escribe a ~illing ccn~pound for ~il ling the sp~ce inside the o-l~er-mo5 pGl~thylen.? jackçt, cr shea'~h, and o~ ;ld~ I t~ outer-mc:st metal~ .c or pl~sti~, s~.ield a~ n~ the conduc~orts~ c~ the cable of tll~ present i.~ven~ion, ref erred to hc~l-ein as the ~-st ~ Ll Lng compollnd. ~o m~k~: t~e secc~nd ~illing ~c~po~Ind ~or use in th~ ~a}~le o~ tlle present inver~ion conc~ ting or semi-conduc~tin~ a mate~ l is added to the m~lerial us~d ~or ~he f'irst ~illin~ c:cmpound which imp.~rt~
conductlng prcpertias to the m~teri~L. l'hUS, the s~cond ~illing compoutld has con~lc~ln~ propert.~es. The se~ond ihg co~p~nd is use.d to ~ the spac~ bet~een, around and o~er ~.e conduc~o~ an~ side o~ the c;uter~ st -. CA 02220113 1997-11-04 ~n~talL ic G~- pla~tic s~ i~lcl, or in tht~ le whioh l~lut~ a~' ~ipla ~tr~lt~cd ccl~du~tor~ Q ~econ~ f illing compound 1 i1ls both th~ spaces ~twe~n et~ detl con~ Lc~ors~
~nd ~ .c;p~c:~ ou~ idc O.c th~ n~ r c;~nductors an~
id~ tr~e outor-mo~t ~hie~cl.
~ UC"I t,ondu~t ing ;~ n~uc:tin~ ~t;erials irlclude carban black, ~raphi~e, sili~a, d~cXld~ 3 varioue ~p~5 o~ c~y a~ Xnowll in t~.e zlrt.
Als~ nclu~G~d withir~ the scop~ ~ t.his invention ~ ~ such ~ateria~ a~IU~c)ll~ e;~lt: solutions, pre~era~ly hallàe, hydroxid~, c~bcna~e, bicar~on~te, nitrit~ .te, rat~, ~ha~Pn ~ ~C
....
~a -.trld r~}lo~yh,l~e s~lt~ Or ~odium, ,~otas~-ium, ca:!cium, r~ nesi-lm, ~;tanga~ese, i~tt, ~nd coppe~ rt~cu~r. ly E~re~rred ~ clutions o~ ma~n~siu~l carbonat~, m~g:l~S:iu~
c:,bLoride, ~ gnesium ~ lfa~., cJnd ~agnes~ pho~p~,~t:~ ~nd ~-ialt~ of so~ium ~n~ c~lci,um ,uch ~s scd_u~ and ~cilcium ~::hlori~3e, ~odi~l~ ;3nd c~.~ci.~;n e~r~at~, ~odium ~ica~bon~t~
~odillm ace~te, sod um sill~a~, so~ium ci~ral ~, soditlm and calci~m fluo~idc:, sodi~ lurosili~a~, sodlum phosph2lt~
~nd ~od_u~n a~d caîclum hydroxid~. The amour~t Or c:~nducting .. . or ~ conr3~loti~nq r,l.~t~rial .~ ed into the second fi.ll_n~
compo-~ild of ~h~ c~ c ~ p~es~n~ inv~nti on varie~
dependirlr; upon th6 part u' ~r ~na~éri~l use,d, the materic~1 ~s~d a~; th~ oil co~pon~r~t of the 'i1Ling cotnpour~d, and ~he c~nd~iVc pro~ertie~ expecte~ arom ~h~ operating p~1ram~ers of _he c~ble. I~hQ ~c~rld~ting or serni-cond~cti terial i ~ene~ally used in .~ weight to w~ight r~t.io of fr~m ahout 15 t~ ' S0 p~r~s to ~bout iOO pa~ts of thl3 oil c,cmpon¢nt 2~ ~he g~l ~natri x .
In i~dAitio~ to the ~at~r absorbin~ properti~5 o ~lLe fillin~ compou~d~ cf th~ c~ble of ~ch~a pr~se3~t lnv~n~icn ~ the ~ cc~spour.~s are su~:h cLS to ~re '' 'u.nction o~ not r~lo~in~ zt ~empcc~tur~: o~ GOO~C and abcl~e.
'~hu;" ~he f ~ ompound~ oL the present inven1:io~l are a~ o wlth~and temper~tures such ~ hose ercounte~ed cLS
a ~esult o~' ~ol~r ~a~nin~ and~or ~uring heavy loads on the po~er t~an~mission line withcut so~1.ch~.n~ and withcut a ~rop in vis~;osi~cy tha~ i5 SC~ w ~}lat the ~illing compound ~lows lengthwis~ in the ~bl~ (~.There there is/are low poi.n~s in the cabie~ or ~v~n à" jpc ~ut o~ tha cable~
l'h~ ~o.~lo~ing ar~ exclmples of ~~irst ~nd second fi ' ling c~omp~nds ~pproprial~e ~o~ ~s~ in th~ cable of the present int~er3tioll. r~h~ exan~pl~s o~ i~il lir~g compounds p, l~pa~ed in Accorc~an~e -~ith the inv~ntion are hot i~tcnded ~o limi~ the ~scope o~ ~he 1nvention and are instead il~' u~rativ~ rompounds used to pr~c~ic~ the inven'cion.
, O
EXAMI~I,I. 1 7~ ~irst s llin~ Compoun~ W~5 p~ep~rcq u.sin~ ~O
parts by wei~h~; polyi~obu~:yl enR oii (~no~ ~NDOPGL 1,-100), 4 l/~ pa--tE; by w~ t polyalp.h~ olL~Fin, and one p~rt by w~iah~ polyalkyl~n~ ~lycol ~ol i n C~eraical C~p . POI,Y-G
~150). ~ol~j~alkyl~l~e ~'y~ 15 a ran~o:n copoly~er with 7~5~
c~ yl2ne oxide and c.5~ prop~ c~r su}~:~titutior~, with an a~/e_aq~ t-.olec~ r weight of ~rom 1 Oa W O 961'36054 PCTrU'~95/05732 12,()00 to 15,000 and a hydroxyl number between 5 to l 0 mgs KOH per gram. The polyisobutylene has a viscosity ASTM D-445 38~C. of 210-227 and the viscosity index ASTM D-567 is 95. The polyalpha olefin used was a long chain polyalpha olefin S,HF -61 5 manu~actured by Mobil which had a viscosity ASTM D-445 AT
~! 38~C of 30.5 and a viscosity index ASTM D-2270 of 132. The pol~yalpha olefins which are used, as exemplified by the S;HF~61 Mo bil product, are typically hydrocarbons with a mo].ecular weight from 200 to 800. The SHF-61 product is an oligomer of 1 -1 0 decene. The satisfactory viscosity range of the polyalpha olefins is frorn 2 centistokes at 100~C. to 100 centistokes at 100~C.
Twelve parts of the resulting mixture was mixed wil h one parl: of pyrogenic silica as a thickener. The resulting gel matrix was blended two parts by weight gel to one part by weight of the 1 5 water absorbent polymer in the form of the partial sodium salt of crosslinked polypropenoic acid, referred to herein as 2-pol~ypropenoate (Dow Chemical Co.). Essentially the same results have been achieved using an identical filling compound inc,luding the polyacrylic acid sold under the brand name FAVOE~ C96 2 0 (Stockhausen, Inc., Greensboro, N.C.). When tested in accorda;nce with ASTM D 150 procedures, the composition was characteri.zed as having a dielectric constant of less than 2.3 and a dissipation faclor of about 0.01, and when tested in accordance with ASTM
D2';7, volume resistivity was about 4.99 x 1012. The composition 25 did not melt when heated to 200~C and had a water response time of under 12 minutes.
A first filling compound for use in the cable of the present invention was prepared in the manner ~escribed in Example 1 3 0 and having the following contents (parts by weight):
DRAKEOL 34 (Penreco Corp.) 6 1 0 REOMET 39 (Ciba-Geigy Corp.) 2.5 BENTONE 24 (NL Chemicals., Inc.) 50 Acetone 10 3 5 AEROSIL R74 (Degussa Corp.) 20 FAVOR C96 (Stockhausen, Inc.) 150 MICROTHENE FA640 (Quantum Chemicals Corp.) 157.5 When tested in accordance with the procedures described in Example 3, the composition was characterized as having a dielectric constant of 2.12, volume resistivity of 5.91 x 10l2, and a dissipation factor of 0.01. The composition did not melt when heated to 200~C and had a water response time under 10 minutes.
Polyesters have also been used to prepare a first filling compound for use in the cable of the present invention. The polyesters ranged in molecular weight from 300 to 800 and have viscosities from 25 to 1 00 centistokes at 40~C . The polyesters were mixed about 10 to 30% of the polymer. The polyesters which have been utilized are esters of trimethylol propane, pentaerythritol and triallyl mellitate, and when tested, produce results similar to those of the compound of Example 2.
A second filling compound for use in the cable of the present invention is made by mixing the following (all percentages by weight):
70% oil-rubber blend (see below) 2 0 8% CABLOC 800SF (Stockhausen) 5% BARAGEL 3000 (Rheox) 15% 665 Grade talc (Montana Talc Company) 2% PRINTEX XE 2 Extra-Conductive Carbon Black (Degussa Corp.) 2 5 The oil-rubber blend is made up of the following (percentages by weight):
94.77% N1500 (Pennzoil) 3.3% KRATON 1701 (Shell Chemical Co.) 1.58% IRGANOX 1035 (Ciba-Geigy Corp.) 3 0 0.35% IRGAMET 36 (Ciba-Geigy Corp.) The second filling compound absorbed water in 1 1-12 minutes, had a dielectric constant greater than 3.67, volume resistivity less than 5 x 106, cone penetration of 152, and 0.8% oil separation after 24 hours at 80~C.
A second filling compound for use in the cable of the present invention is made by mixing the following (all percentages by weight):
WO 96;/36054 PCTI~S95105732 82% oil-rubber blend (see Example 4) 5% AEROSIL R74 (Degussa Corp.) 8% FAVOR C96 (Stockhausen, Inc.) 5~o aqueous solution of mixed metal salts 5 The mixed metal salt solution was comprised of water and several salts of calcium, sodium and magnesium, the concentration of all such salts aggregating to less than 1 ~o. When tested as described abc~ve, the dielectric constant of the compound was 3.22, dis~iipation factor was .0321, and volume resistivity was 71.89 x 10 10~;.
A second filling compound for use in the cable of the present invention is made by mixing the following (all percentages by weiight):
1 5 77.5% oil-rubber blend (see Example 4) 4.5% AEROSIL R74 (Degussa Corp.) 8% FAVOR 900 series polymer (Stockhausen, Inc.) 10% aqueous solution of mixed metal salts (see Example S) 2 0 When tested as described above, the dielectric constant of the compound was 3.78, dissipation factor was .0356, and ~.~olume resistivity was 28.7 x 105.
A second filling compound for use in the cable of the present 2 5 inv~ention is made by mixing the following (all percentages by wei ght):
71.03 % N 1500 (Pennzoil) 2.47% KRATON 1702 (Shell Chemical Co.) 1.18% IRGANOX 1035 (Ciba-Geigy Corp.
1.31% IRGAMET 36 (Ciba-Geigy Corp.) 4% AEROSIL 200 (Degussa Corp.) 8% FAVOR 900 series polymer (Stockhausen, Inc.) 2% polyglycol 10% aqueous solution of mixed salts 3 5 (see Example 5) When tested as described above, the dielectric constant of the connpound was 6.95, dissipation factor was .2766, and volume CA 02220ll3 l997-ll-04 r ~si~'civl~:y w.~=, 2, ~3 ~ )6. W~t3r ,I~;crp.ion t~i:nes; were a~ s ~ s .
t * 1~ * ~ 1.
R~ rrin5~ no~ to t:he f i~ re~, 5howr. in sche~nat:ic ~-~p~esen'~ )n ic: a ~hod ancl ~pp,~a~us fcr ,na~i~g a powe~
~,~ansm~ Jl cable ir.cllldi~g the first ~nd ~econd fi.lling coTrpound~ o~ th~ p~eC;e~t inv~nt;1 or~ such as the cable shcwn Ln ~ u~c z. Such a cabl~ icat~d ~enPrall~ a~
-ef~encP r~u~ner~i~ 10 i~ ~-ompr~cd o~ a plurall~y o~ wir~s, cr c~du~~r~, 12 cont~in~l in ~ ~2ckP'c 1~ i n ~he ~orm of --~ a poly~neric, ~he~th as k~lown in -~ ar~, ~hich may be ~ormed y po.l ye ._~v I en~ .
To ;nek~ ~he cabl? ~ O, t;hc~ conducto3; ;Z are ~wn thro~h ~ I illir.~ ~~t~arlr6r 16 rf.o~nt~l ir. a filling head s~ ~nd 12 ln whic~l thc se-~on~ c-:~tnpound 23 o~- the c~bl~: o~ tt-e pre~ent irlvention i~ e~ruded on to the cor.~uc or~ compri~ir.~ t;3e csi~ c~rc. Five cond~lc~ o:~s 1G ~e ~how~- erlt~in~3 ~ch o~ fi~,e ~illing chambers lG in Fi.~,ure 1 . 'L'he I i ~ ling cha~b~_ s J.O n~ r ~ n~ char:l~er ~;t~ld 1~ a-e ~.cu~tP~ on the sha~.s ~2 of ~nd ~scil' a~ed by an osc~ lla~,in$ ~ c~lne 24 cf ~! ' ype Xnown in th~ ustry, and th~ f:ive co.sductors ex~ing fllling cl~m~ers 1~ a~e pas~d th_;~ugh a si~inc inse~ ~not sho-.n) ~ ow:~ in the a~.t ~o that ~h~e am~Ln~ o f second ~illinq c~rr.pound e.Y~,~uded in th~
5~2C2 bet~tre~n and on to each con~Lc~. 12 is standardi.sea~.
A~ thc c~nduc~orc, 12 ~it os~iLl~.inq machine 24, ~chey ar-e br~ h~ toy~ther ~d a convent.icn~ e~ conductive l.ay~r 2~ (~hic;h ~;~y be a pl~stic lnaterial) i~ wrapped or exir-uded OVi~ L' i Ll in~ compoun~ at ~ t i l l ~ n~ s~tion ~;hown scher~atic~lly (becau~e it 1~ know1~ int h~ art) a~ ref~3nc~
r~ume~1 7.~, the l~ye_ 26 fc3-mi~g a conductor s~~esS ~ntrol ~ayer~ Thc l;~y~r ~6 is then ~nci.~cled by a laye~
polymc~ s~lati~:~ 30 ~u~h ~s poly2-~hyle~ ~hich is extruded ~ extrLlder s.ati.on 3Z. ~rhe second fillin~
colr.pound i~: located in thY spa~d Det-~eert the ccnduct~rs 12, ~nd ~lsa be'citeen ~he conduc~crs 12 and the layer ~
.
CA 02220ll3 l997-ll-04 irl~,uli~tion .~o. ~ se~nd pla~ 5.re55 cont;ol laycr 3~
.n~y al~G 1~ x~;rudec~ ~/c~r the l~ye~ cf insula~ion ~ at:
anoth~r ~t~lt' on ~c~ lso ~own st:h~ms~t lcally~
A me~al shield 3~ the losn~ of ~ ccpper ~r all:;inillm ~;-pe c~, s~ri,~, is then helic:;~lLy wound aroun~ the ~undie~, ins-;_a~Gd, ar~d _illed con~ tor~ at st~tion ~0 in a ma~nc~ kno-~rl in the in~ust~ . The sni~ldad c~ndl~tors ~l-e ~ n d~w~ in~o ~ second ri~ ~ i r~ head 42 ha~ g a ch~b~r si~i.la~ ~o ~.n6 chL~kcr~ ~ 6 mounted ~herein .~sr e~:trudln~ the ~i~s ~ f i'~ lin~ c ~m~pcl~n~ ~ ~ o~r and ~und ~:h~
bunc~lc~c~, insul~.t~d, t'~. ! Icd ~nd shielaed condu~tor~ ~2.
Upon exi ~ i~t; ~ ll il-~g l~ad ~.Z, th~ c~ble ifi th~n 2r~c;ircl c~
by a j a~,}cer. lq by o~Y~rusion o~ a pol~eri - material at ex~_ude.r ~t~tion 46.
The sec~d ril 11~$ com,pound ;i~.t) of thc ca~lc~ ~l the p~ cnt i~v~n _io~ is ~ p~d into t~c f~il l i~g cha~bers 16 at 2pproxima~el~,~ ~oom tamper~ture a~d i5 maintairled under p~es~ure _o as ~o ~;~ci. I lt~t~ e~t~ usi on orl ~o th~ c~nd~ctors 12 . A si;~ilar ar~s~ment an~ c~hditc~ 0~15 i~C used in th~
~e~o~d ~illing he~ci ~ or extru~ on OL ' he fir.~t Ci.l lin~
coinpound 4 4,
Claims (7)
1. A power transmission cable (10) comprising at least one central conductor (12); a layer of insulation (30) around the conductor(s)(12); a metallic and/or plastic shield(38)over the layer of insulation(30); a polymeric sheath(14) around the shield(38); a first filling compound(44) located between said polymeric sheath (14)and said shield(38); and a second filling compound(20) located between said central conductor(12) and said layer of insulation(30) characterized in that the first filling compound(44) comprises a dielectric gel having a wather reactive polymer dispersed therein and said second filling compound(20) comprises a gel having a water reactive polymer and a conducting or semi-conducting material dispersed therein.
2. The cable(10) of claim 1 wherein the cable comprises a plurality of central conductors(12)and has said second filling compound(20) located in the spaces between said conductors(12).
3. The cable(10) of claim 1 or 2 wherein the gel of the first filling compound(44) and of the second filling compound(20) comprises an oil and a thickener.
4. The cable(10) of any one of the preceding Claims wherein the shield(38) is metallic.
5. The cable(10) of any one of the preceding Claims wherein the polymeric sheath(41) is of polyethylene.
6. A method of manufacturing a power transmission cable (10) comprising the step of making first and second filling compounds, the first filling compound being made by dispersing a water-absorbing polymer in a non-heat melting gel matrix, and second filling compound being made by dispersing water-absorbing polymer and a conducting or semi-conducting material in a non-heat-melting gel matrix, forcing the second filling compound into a chamber(16) under pressure and moving one or more conductors(12) through the pressurised filling compound in the chamber(16) by passing the conductor(s) through entry and exit openings extruded on the conductor(s)(12), and/or into the spaces between the conductor (12)applying insulation(30) thereto and a metallic and/or plastic shield(38) and an outer polymeric sheath(14) and filling the space outside of the shield(38) and inside of the outer polymeric sheath(14) with the first filling compound(44).
7. A method according to claim 6 wherein the gel matrix of the first filling compound(44) and the second filling compound(20) comprises an oil and thickener.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP95919757A EP0830691A1 (en) | 1995-05-09 | 1995-05-09 | Non-water permeating power transmission cable |
| PCT/US1995/005732 WO1996036054A1 (en) | 1995-05-09 | 1995-05-09 | Non-water permeating power transmission cable |
| AU25444/95A AU2544495A (en) | 1995-05-09 | 1995-05-09 | Non-water permeating power transmission cable |
| CA002220113A CA2220113A1 (en) | 1995-05-09 | 1995-05-09 | Non-water permeating power transmission cable |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/US1995/005732 WO1996036054A1 (en) | 1995-05-09 | 1995-05-09 | Non-water permeating power transmission cable |
| CA002220113A CA2220113A1 (en) | 1995-05-09 | 1995-05-09 | Non-water permeating power transmission cable |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2220113A1 true CA2220113A1 (en) | 1996-11-14 |
Family
ID=25679796
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002220113A Abandoned CA2220113A1 (en) | 1995-05-09 | 1995-05-09 | Non-water permeating power transmission cable |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0830691A1 (en) |
| AU (1) | AU2544495A (en) |
| CA (1) | CA2220113A1 (en) |
| WO (1) | WO1996036054A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6331353B1 (en) * | 1999-08-17 | 2001-12-18 | Pirelli Cables And Systems Llc | Stranded conductor filling compound and cables using same |
| US9117566B2 (en) | 2013-03-14 | 2015-08-25 | Teledyne Instruments, Inc. | Impedance controlled subsea ethernet oil filled hose |
| GB201305519D0 (en) * | 2013-03-26 | 2013-05-08 | Jdr Cable Systems Ltd | High Voltage Cable |
| CA3140276A1 (en) * | 2019-05-20 | 2020-11-26 | Nkt Hv Cables Ab | Hvdc power cable with water-blocking capability |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2465301A1 (en) * | 1979-09-07 | 1981-03-20 | Jeumont Schneider | High tension electric cable - has screening wires embedded in sealing material to ensure water tightness even after local damage |
| US5010209A (en) * | 1988-12-20 | 1991-04-23 | Pirelli Cable Corp. | Power cable with water swellable agents and elongated metal elements outside cable insulation |
| WO1990012406A1 (en) * | 1989-04-07 | 1990-10-18 | Freeman Clarence S | Communications cable including composition for protecting the wires thereof from damage by invasive water |
-
1995
- 1995-05-09 CA CA002220113A patent/CA2220113A1/en not_active Abandoned
- 1995-05-09 WO PCT/US1995/005732 patent/WO1996036054A1/en not_active Application Discontinuation
- 1995-05-09 EP EP95919757A patent/EP0830691A1/en not_active Withdrawn
- 1995-05-09 AU AU25444/95A patent/AU2544495A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1996036054A1 (en) | 1996-11-14 |
| AU2544495A (en) | 1996-11-29 |
| EP0830691A1 (en) | 1998-03-25 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| FZDE | Dead |