CA2194230A1 - Electrical interconnections - Google Patents
Electrical interconnectionsInfo
- Publication number
- CA2194230A1 CA2194230A1 CA002194230A CA2194230A CA2194230A1 CA 2194230 A1 CA2194230 A1 CA 2194230A1 CA 002194230 A CA002194230 A CA 002194230A CA 2194230 A CA2194230 A CA 2194230A CA 2194230 A1 CA2194230 A1 CA 2194230A1
- Authority
- CA
- Canada
- Prior art keywords
- housing
- resilient
- sealant material
- stress cone
- 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.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G15/00—Cable fittings
- H02G15/08—Cable junctions
- H02G15/18—Cable junctions protected by sleeves, e.g. for communication cable
- H02G15/184—Cable junctions protected by sleeves, e.g. for communication cable with devices for relieving electrical stress
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G15/00—Cable fittings
- H02G15/08—Cable junctions
- H02G15/10—Cable junctions protected by boxes, e.g. by distribution, connection or junction boxes
- H02G15/103—Cable junctions protected by boxes, e.g. by distribution, connection or junction boxes with devices for relieving electrical stress
Abstract
A 15kv cable joint is enclosed within two half shells (38, 40) filled with sealant material (46). Displacement or thermal expansion of the sealant (46) is accommodated by various configurations of stress cones (34C) that have apertures (70) or surfaces that are flexible and arranged to maintain pressure on the sealant (46) for example during thermal cycling of the joint.
Description
w096102079 ~1 942~l~ Pcr/Gss~l0l623 FT.F.CTRlC'Al. INTF.RC()NNF.CTIONS
This invention relates to the protection of electrical i..:- ~ . "." ~ Such i..;...u,....,.liu.~ may be between two or more electrical cables (i.e. in-line or branch joints), between two or more pieces of other electrical equipment such as ~. DrulL~ and switchgear, but which may also include anodher cable or between cable and equipment, includhng cable adapters and t. . ,ll; ~ Such an hl;~lcolLI~.,Liull usually needs to be protected against ingress of moisture IO h.:.l.ulL~.t d conductors, and to provide electrical insuiation li...~., ' Additionally, at voltages above about 10kV, some form of electrical stress control is usually also desired. The invention is generally applicable to electrical Lli~lCUIhl~liUIID at lûw voltage, typically aro~und I to 10kV, at medium voltage, typically around 10 to 36kV, and also at high voltage, typically greater than 36kV.
Various ~ exist for protecti.ng such i..t~", . ." l i. " ,~ some of which are more applicable to one voltage range rather dIan another, and some applicable to cables, for example, of one material, for example polymeric, then anodher, for example paper.
Amongst these t~ l ~Ir,~;. s may be mentioned polymeric heat shrink. elastomeric push -on and roll-on, elastomeric hold-out. tape windmg, hot bitumen filling, and cold-pour resin systems. Pending Raychem US Patent Applicatiùn Serial Number 081138360, the contents of which are now published in l,.~ i"" l Application Publication No. WO 95/11543, discloses a power cable joint which is flled by a Cull~ D~;l/le sealant material such as gel, which has been found to have ~u~ h~ly good p...u....~...
The present invention is particularly concerned widh an h~ between an electric cable and other electrical equipment in which a cu~ lc~i,,lc, and preferably oil-extended polymeric, sealant materiai is employed to seal and to provide electrical insulation around the connection.
Thus, in accordance with one aspect of the present invention, there is proi ided an enclosure arranged to enclose a connection between a screened electric power cable and anodher piece of electrical equipment, the enclosure comprising a housing, at least one ~ electrical stress cone contained widlin the housing, and a quantity of cu~u~,.,.;bl~ sealant material that is contained by the housing and that Du1~KIllLi.llly fills the housing when ~ encloshng the ill.~.CUlhl~ , wherein dhe or each stress cone comprises resilient aperture means dlat is arranged to change its volume in response to a change of volume of the sealant material thereby, in operation, to maintain substantially complete ftiling of the housing around dhe Ll~ ullu~Liull widhout the formation of voids therein.
SUESTITUTE SHEET (RULE 26) WO 96102079 : PCT/GB95101623 2194?3~ ~
The resilient aperture can thus adapt to the volume of the sealant material as it changes in 2~sponse to change in tVlll~ di~ of the substrate or of its amhient au~Luulldillo~
or to other external pressure. The sealant material al~dl.LO~,Jualy adheres to the resilient means so as to minimise the likelihood of a void forming as a result of movement of the material.
The aperture means may expand, or stretch, as the sealant expands, or it may be arranged to be in a relaxed cullBo~.dliùu when the sealant is in its expamded state. which is expected to be the state it occupies most of its time in operation.
In many ~ of the present invention, it is dd~ o~u~l~ for the resilient aperture means ~o exert a continuous pressure on the sealant material. Howe~er, when t,he sealamt material comprises a ~ ", of solid and a liquid component, such as a gel comprising an oil-filled polymer for example. the pressure should not be such as Io urge the liquid component ~io~drl~d~l-ly out of the complete system.
The aperture means may be provided by a vaid or gaseous entrapment contained completely within a resilient portion of the stress cone, or located between a resilient portion of the cone and a non-resilient portion of the housing.
A spring and plunger 2 v may be provided ro as to prevent the forrnation of voids in the h~ ul~l-~Liull. Alternatively, a resilient wall may be arranged as a diaphragm to exert, or to maintain, pressure on the sealant material.
The sealing is typically required to provide a block to the passage of air, moisture, or other fluids.
The sealmg material of the invention may geneMlly comprise any cu.~ c~aiv~.
sealing material, e.g. mastic or grease (especially a highly viscoug grease such as a silicone grease). Preferably, however, the sealing material comprises cured gel.
The gel may, for example, comprise silicone gel, urea gel, SEBS, SBS, di- and tri-block copolymers and blends thereof~ urethane gel, or any suitable gel or gelloid sealing material. Preicrred gels comprise oil - extended polymer ~ Preferably the gel has a hardness at room i , c as determmed usmg a Stevens-Voland Texture Analyserof greater than 48g, particularly greater than 14g especially greater than 18g, e.g. between ~aULSTlTUTE SHEET ~RULE 26) W0 96/02079 21 9 4 ~ 0 PCTIGB9~/01623 18g and 29g. The test settings of the Analyser should be: speed = 0.2mrnJsec; penetration = 4mm; and sphere diameter = 0.25 inch. It preferably has a stress-relaxation less than 609'o, particularly less [han 50% and especially less than 40% and preferably grea~er than 10%. Ultimate elongation, also at room t~ ,lalulc, is preferably greater than 100%, especially greater than 200%, ~ u~ iy greater than 400%, as determined according to ASTM D638. Tensile modulus at 100% straim is preferably al least 1.8 MPa more preferably at least 2.2 ~IPa. In general cv.lll~lc,~iu-l set will be less than 25~o, especially less than 15~o. Preferably, the pel has a cone penetration as measured by AST~vi ~217 of at least 50 (lO~1mrn), more preferably at least 100 (lO~1mm), even more preferably at least 200 (lO~Imm) and preferably no greater than 400 (lO~Irnm), especially no greater than 350 (10-1mm). Reference is also made to US Patent No. 4852646, especially Figure 3 thereof, for alternative gel parameters., showing the l.,l~tiol.,l i~ between the Voland Hardness and the Cone Penetraion value, the entire contents of which are included herein by tilis reference. Also, reference is made to tne suitable materials disclosed in US Paten~ No.
5079300, the entire contents of which are included herein by this reference.
Aiternatively, the polymer e. ", ~ , of the gel may for example comp}ise an eiastomer, or a block copolymer having relatively hard blocks and relatively soft elastomeric blocks. Examples of such copolymers inciude styrene-diene block copolymers, for example styrene-butadiene or styrene-isoprene diblock or triblock copolymers, or styrene-ethylene-butylene-styrene triblock copolymers as disclosed in i ~ l patent publication number W088/00603. Preferably, however, the polymer Collll)u~;~iull comprises one or more styrene~ethylene-l,.u!,yl~ styrene block copolymers, for example as sold under the Trade Mark 'Septon' by Kuraray of Japan. Septon 2006 is a particularly preferred grade. The extender liquids employed in the gel pre~erably comprise oils coll~,l.dul~lly used to extend elastomeric materials. The oils may be h~ GIbUII oils, ~or example paraffinic ornaphthenic oils, synthectic oils for example polybutene or puly~JIutJ~ oils, and mixtures thereof. The preferred oils are mixtures of non-aromatic paraffins and naphthenic h.1llul,albull oils. The gel may contain kno-vn additives such as moisture scavengers (eg.
Benzoyl chioride), -~ i.t ,~, pigments and fungicides.
The gel used in the present invention adv.ulL~ ,u~.~ly has a dielcctric breakdown strengtn of at least 18 KV/mrn, preferably greater than 24 :KV/mm, being in tne preferred ~ range of 24 to 50 KV/mm, but could even be as high as 100 KV/mm. These vaiues apply not oniy to the bulk values of tne gel itself, but also to any mterface between the gel and other materials with which it has contact in the ;,.~., ' The preferred gel material comprises a silicone gel, being a silicone polymer extended with an inert siiicone oil.
SUBSTITUTE SHEET ~RULE 26) WO 96/020~9 r~ '7~
21 9~30 It will be undersLood from tbis document that the term ~culllul~a~il/l~" in the context of the sealant material reFers tu a material that. upon being subject tu an external pres.sure. is cvl~ caaibk so as to flow around an enclosed substrate. The pressure may arise from the housmg that contains tae sealant material being applied to, for example closed around, the electrical; ~ u ~ or from thermal expansion of the sealant material. With the preferred sealant material being a gel, the ~:u---,u-c~ c force resuls in ~ ,,. andlor p ~ that allows substantially complete conformity with the substrate, which confornnity can be maintained even under thermal cyclimg.
The connection will typically be of substantially cylindrical ~ i;lll The present invention is of particular dl~l/l;.db;li~y in connections in which the housing consiss of two, or more, inter-engaging ~ullluull.llLa, for example two half-shells. In such a cullrl~uldiiull, the stress cone is also ad~dllLd~,~,uualy formed of a plurality of uuul,uù~m~, for example two half-cones taat mate on closure of the housing, so that tae iUIL~I~
caLn c()~ ,.ily be formed in a rldj~dlUUllPi manner around the already-made electrical comnection, for example a crimp. Conveniently, the gel sealant is supplied as a filling contained within each part of the housing, which then seals the interf~e Lh,_.cb..~ The advamtages of this cu~ . .dlioa, especially when using a gel as the sealant, are discussed in pending Raychem US Patent Application ~Serial Number 081138360 (WO 95111543), the entire contents of which are included herein by this reference. In particular, the A ' ' "ly high dielectric strength found at the interface of the two portions of the gel, and ihe excellent adhesion of the gel to the ~ of the L t l-UlUl~iiUII, such as the cable materials ~usually pul,~,;i-yl-,.. or l~ul~vi--~lid~ chioride), substantialiy prevent air pockets to exist iil~lCh~ ll and allow a cable joint, for example, to he made of a much-reduced length than has previously been possible. A shorter length joint requires less cable preparation, and ti-ius less time to complete, this being particularly so when the cable system is buried in the ground.
The housmg used in the invention, preferably formed from two inter-engaging halfshells, is preferably made of a conductive polymeric material, having a volume resistivity of the order 10' ohm-cm. A~ ,gr..~ its material is carbon-filled i u.~,u.u,u,~i. ..c.
Alternatively, the housing may have an insulating imner component and a conductive outer component, to provide the required screening function. As othcr options for the housing, there may be mentioned a push-on dlldLc~_ ~. i that is stretched over the ;~ - o .... or a revolving sleeve as disclosed in US Patent Number 4868~,67. The housing that seals the electrical hl.~ .Liu.. dd~GlllAb_UU:lly has at least a portion of a wall thereof that is subject to the pressure of the sealant material formed so as to flex m order to: ' SUBSTITUTE SHEET (Rl!LE 26) wosc~o2079 21 ~3~ p ,,~ 623 change of volume of the sealant material. The resilient wall section may be bounded externally by a non-resilient wall portion so as to defme a ~i~r~ Pnn~nl cavity ~ ,v~
which cavity may contain resilient means. It is also envisaged that a major part of the housing surface (ie >50~0), and adval~ v~..ly ~ Dia.l.idlly the whole of that part of the surface that p.,li~L~Ia:l~ encloses the sealant material, is resilient. The housing may be deformable such that it is able to change from a cross-section of one shape to a cross-section of a different shape that encloses a larger volume. For example, the housing may be arranged to change from a generally oval to a substantially circular cross-section.
In order to contain the sealant material, ,udlLi-.h all~ though not exclusively when it is a material such as an oil-extended polymer, when it is subject to a cv~ ul~ , force on closing Lh~l~,alvullll of a housing, formed from two half-shells for example, it is preferred that the closing edges of the housing overlap before final closure takes place, and thus before significant ~ . ., pressure is exerted on the sealanL material, In the case of two nngih~rlin~ y-extending half-shells, for example, a projection along the l-~ngih~in~l edge of one half may engage a channel along the other edge. The sealant material is thusr C llfldlly contained within the closing housing before sufficient pressure is exerted on the sealant material to exude it laterally out of the housmg.
Means may be provided to restrain movement of the housing rotationally and/or Inn~ihl~:in~ y with respect to its substrate, which may be an electrical hlL.,Iuu...~,.Liuu for example.
A flexible part of the closed housing, ûr of another component within the joint that is subject to, and contains the pressure of, the sealant material, may be arranged such that the flexible portion follows any conhraction of the sealant material so as to avoid the formation of any pockeLs of air.
The Faraday Cage member is preferably of a conductive ~ material of similar resistivity to that of the conductive housmg, but it may -' ' r~,ly be formed of metal or metallised plastics material. The conductive Faraday Cage member is ad~ v..~.ly resilient so as to exert pressure on the sealant material, thereby ~ub~L,~uliall~
to prevent the formation of voids within the housing outside the conductive member contained thereim. Preferably, the conductive member has at least one void or gaseûus entrapment completely contained therewithin that is subject to the pressure of the sealant material. The support cradle for the Faraday Cage is preferably formed of an insulating ~h.. ~ ' material. The support member can ~uu.. llLly be secured to the housing so SUBSTITUTE SHEET (RULE 26~
wo 96102079 pcrlGs9slol623 't~4~3~ /~
as posi~ively to locate the conductive Faraday Cage member within the flo~able sealant materiai.
The stress cone used in the invention may be made of a conductive rubber or elastomeric material, EPDM for example, typically of volume resistivity 103 ohm-cm.
The enclosure may comprise a seaiing member, acting as a stress-relief cone for example and the sealing member a.l~...lL~,cuu~ly comprises (a) a relati~ely rigid component and (b) a relatively resilient component, which may haYe at least one aperture therein. The relativeiy rigid component is arranged to urge the relatively resiiient component in20 substantially complete conformity around the substrate, and the seaiing member is thus able to: ' a range of substrates, electric power cables for exarnple, of different sizes, usually diameters, whilst ~ a good, substantially void-free seal therearound.
It is to be understood that the materials of each of the ~ used in the invention are to be selected so as to be compatible with any component with which they come into contact and so as not to have any adverse reaction therewith, especially over longer time periods.
In accordance with another aspect of the present invention, there is provided anillt'_l~,U~,~iUIl between a electric cable and another piece of electricai equipmenn the ,ICo~.,~iu.l bemg enclosed within an enclosure in accordance with the first aspect of the mYemion.
The other piece of electrical equipment may be, for example, another elec2rical cable, or equipment such as switchgear or a L~dll,ru.ll~ to which the said cable is connected, or other equipment at which the said cable is terminated.
Enclosures and hlLI.~ in accordance with the present invention are hereinafter described especially ~ith reference to Figures 1 to 6 and Figure 8 of the a~cu~ l.riu~ drawings but it is envisaged that features of other Figures may also be included in such enclosures or illa~ "'. for example, the features associated with the Faraday Cage ~Figures I and 13), the housing (Figures l, 6, 14 to 20 and 23 to 25).
Fu~ ulc, the present invention may aiso encompass the Faraday Cage suppor2 features (cAcull~lir~l in Figures 21 and 22), and may employ a range-taicing seaiing member (as exemplifled in Figures I, 7 and 9 to 12). Some of these fearures are the subject of aur SUBSTITUTE SHEET !~ULE Z8?
WO 9610tO79 2 1 9 4 2 ~ ~ PCT/GB9S10 1623 patent ~pplir~ti~ m filed l Vll . ~ JUl~ OU~ly herewith, under our references RiC503, RK505 and RK506, the entire disclosures of which are i~u~Jv~lL~d herein by this reference.
SUBSTITUTE S~ EET (RULE 26) WO 96/02079 PCT'/GBgW1623 '~J,1 qL~23;') - S -F." ,1 u ~ of the present invention will now be described, by way of ex~unple, with reference to the a ~~ yhlg drawings, in which:
ure I shows crhr~m~irrlly a cross-sectional elevation of an in-line joint between two screened lSkV power cable joints, foml~ B~ the general principles of theinvention;
Fi,~rPc 2. '~ show crhPm~-~ir~lly a first P..lllr)r~ of the invention in which astress-relief cone of the joint of Figure I is arranged to - ' expansion of sealant material of the joint;
Fi~ure ~ shows another fonn of stress cone to that of Figure 2;
Fi~nrPc 4~ 4A show still ;mother form of stress cone, in section and in isometric view ~ .,;y, Fiel~r-~ 5~ 5A show another variation of the cable joint of Figure 1, in which sealant ~ expansion is ~ in section and in isometric view r~ d~ly;
Ei~i shows a partial section through one half of a modifed joint:
h~Q shows another form of stress cone for use with the joint of Figure l;
Fi~ure 7~ shows a cutaway view of the stress cone of Figure 7;
Fieure 713 shows a reverse angle isomctric view of the stress cone of Figure 7;
~ shows a further ..,..B;li. ~ of a str~s cone for ~ sealant expansion within the joint of Figure l;
Fieure 9 shows a dis-assembled view of one half of a modified i~ of outerhousing and sLress-relief cones for use in the general joint C~ Llu,Liull of E'igure l;
Fieure ID shows a cross-section through a completed joint employing a stress cone as shown in Figure 9;
SUBSTITUTE SHEET ~F~ULE 26) WO g6102079 ~ 1 9 4 ~ 3 ~ PC'T/GBgSlOlG23 ..9 Fi~lr~c 11 an i 1?. are isometric views of the rear end of one half of a modified range-taking stress cone;
Fi~-rr~ 1 ~A. l ~B an(l l ~C illustrate ~ lly features applicable to the Faraday Cage of the joint of Figure 1 for ~r~ expansion of t. e sealant material of the joint;
Ei~lg shows crh~ m~rir*tly one n"~ l;r~ ; of the housing of the joint of Figure I for ~ ~ ~ ", .~ i . .o expansion of the sealant material;
Fieure 15 shows a furiher ",(,.I;r~ o~ of the housing of Figure 1:
EiE~l~ shows an isometric view of one half of a further . - --).1;1;, ~1 ;l ~ l in w hich an integral insert provides for gel expansion and includes stress cones;
Fi~l~rpc 17 ~nri 18 show sections along lines B-B and A-A respective of Figure 16;
F~lr~ 19 :m(l 20 ~ lI,y show a ...o(liri ~ .. of the outer housing of tne joint, formed from three c~
Figure 21 shows crhrm~tir~lly one a~ .L,. .". .a in which a Faraday Cage of a cable joint may be supported when it is enclosed by non-rigid material;
Ei~~~ shows another ~ ~ ' of suppOn for a Faraday Cage;
Fir-re 21~ shows a cross section tnrough part of a joint employing tne support member of Figure 22;
F~r~r~C 2~ an~l 2~ show cllll,o~l,..l.,ll.~ in section of a seal along the l~ngin edges of tbe two half shells of tne housing of the joint;
F~re ?~ B shows a cross-section through a modified joint showing a Ir,ngi~llrii closure ~ , Ei~2~ is an isometric view of one G ~ of a completed joint; and SUBSTITUTE SHEET (RULE 26) Wo 96/02079 2 1 9 4 2 3 ~ P .i ~ .!~bl623 .
Fi,2ure 25 is a side vieu of a further ~ 1 of housing.
Referring to Edgure 1, the in-line joint is formed between two substantially identical polymeric cables 2, 4. The respective outer jackets 6, 8, screen wires 10, 12 screen layers (semi conducting or conducting) 14, 16, primary dielectric layers 18, 20, and conductors 22, 24, are ~u..~ cut back rn standard manner. with the screen wires 10, 12 being folded back o-er their respective jackets 6, 8 for subsequent i.~ l U...._~iiUII (not shownJ across the joint so as to maintain earth continuity. The conductors 22, 24 are electricaliy...L~ ,~d by means of a crimp connector 26, although any other suitable type of connector may be used. Electricai stress control of the conductor comnection thus made is provided by a member comprising two generally semi-cylindrical half shells 28, 30 made of conductive polymeric material that are brought together around the casing 26 between the two cables and which I ~, " 'iy extends a short way over the cable dielectric layers 18, 20. Each half shell 28, 30 has tbree inwardly-directed projections 32 that rnake electrical contact with the crimp 26 to ensure that the half shells 28, 30, and the conductive rnn~ n.c enclosed therewithin are maintained at the satne electrica] potential. rlamely the potential of the cable conductors. The haif sheMs 28, 30 thus provide a Faraday Cage effect around the crimp 26 and exposed conductors 22, 24. It should be noted tnat the half shells 28, 30 do not seai on to the cable dielectrics 18, 20.
Stress-relief cones 34, 36 are provided for the respective cables 2, 4 and are located so as to provide a conical surface directed away from the cut hack ends of respective sbields 14, 16 in the usuai manner. The stress cones 34, 36 are formed of a conductive rubber and are each provided as a pair of half cones for assembling around the cables 2,4 after the electrical connection ~ ,.. has been made.
The stress cones 34, 36 and Faraday Cage 28, 30, nre completely enclosed within a pair of generally semi-cylindrical outer hinged half shells 38, 40 rnade of conductive polymeric rnaterial, namely carbon-f lled polypmpylene, that fit together to form a cylindrical housing that clamps around the cables 2, 4 so as to seal do vn on to respective cable jackets 6, 8 to each side of the joint.
An electrically insulating support cradle, formed as two semi-cylindrical ~ t~
42, 44, is secured to the outer surface of the Faraday Cage 28, 30 and to the inner surface of the outer housrng 38, 40, so as positively to locate the Faraday Cage 28, 30 both l~n~ih~ y and radially within the joint and thereby to enstlre electrical isolation of the Faraday Cage from the outer housing.
SU~STITIJTE S%E~T [RULE 2~) wo g6,020,9 ~ I q 4 2 3 0 PCT/GB9Sml623 The space remaining witnin the housing 38, 40 around and within cradle 42. 44 and the Faraday Cage 28, 30, and lo~ .i;,l..lly bounded by the stress cones 34, 36, is completely filled with an electrically-insulating silicone gel 46.
The ~..).l ~pl " l " ~ of the joint are assembled by locating respective ones of the support cradle 42, 44, the Faraday Cage 28, 30 and the stress cones 34, 36 within respective housing half-shells 38, 40, pourmg the gel 46 in liquid, un-cured fortn into each half shell up to its rim, and then allowing the gel to cure. The cables 2, 4 are then prepared by being cut back, the conductors 22, 24 secured together by the crirnp 26, and insulating, stress relief and screening are then provided simply by clamping the prepared housing half shells 38, 40 Lh.L~uuulld The securing together of the half-shells 38, 40 brings together the generally planar surfaces of each portion of the gel 46, which then provides a high dielectric strength interface, not oniy gel-to-gel where the half shells meet, but also on to the enclosed y.~ of the cables 2, 4, such as the dielectrics 18,20.
As the two half shells 38, 40 are closed around the jomted cables 2, 4, the gel 46 is subjected to a l,uul~ ., force such that it flows around all of the ~ and conforms therewith. Air present around the jointed cables is thus forced away and its place taken by the deformed gel 46. It will be appreciated that before closure the gel 46 "y fills the half-shells 38,40 to their rims. Accordingly, upon closure around the jointed cables, a quantity of the gel 46 is displaced, and this has to be ~ d by the .u~LL~,du~l of the joint. F ULI~.,I111U~, thermally cyclmg of the power cables 2, 4 gives rise to expansion of the gel, which also has to be . ~ ~ ~ F "1 r~.1; ' of ~le joint disclosed hereinafter solve these problems.
Further details and features of the general ~u.._.lu~,Liuu and assembly of such a jomt are given im pending US Patent Application Serial Number 081138360 (WO 95111543) of Raychem Corporation, the entire contents of which are included herein by virtue of this reference.
The following Figures 2 to 25 show ir. further detail specific features of the cable jomt of Figure 1, and variations thereof, each m accordance with various aspects of the present invention. It is to be understood that all ~I..,.l.;" - ;.,.~ of two or more features herein described are considered as ~ ' of the present im~ention, except where such a c.. 1.;.. ~ " is obviously non-operable.
SUBSTITUTE SHEET (RULE 26) wo 96/02079 Pcr/Gss~ 623 ~11 1 q ~L f~ '' f~) Referring to Figures 2 and 2A, a stress cone 34A, in two generall~ semi-cylind.rical parts, is a ",r.~l;ri. ~, i. ", of the basically configured stress cone 34 of Figure 1. It is iormed within the housing 40 so as to define an annular void 50 therewith. The cone 34A extends away from the cdge of the screen 14 with a leading edge 52 of the cone 34A sealing on to the housing 40.
The gel 46 is seen to fill the volume within the housing 40 around the cable dielectric 18. Figure 2 shows the al.~",~ of the cable joint on mstallation, with rhe cableunpowered and cold. In operation, the cable conductor can reach operating r~ U~ of up to 95 degrees Celcius, and in some instances even higher. Under these condhion tbe gel in the joint, typically being a quantity between about 200 grams and about 300 grarns, can extend up îo 20% in volume. and with a ngid outer housing 40, the expansion bas to be d' ~ ' d within the c.,llr"--lali.", of the joint. In the present c~lJodi~ ll, expansion of the gel 46, acting OD the relatively soft rubber of the stress cone 34A is arranged to compress the v oid 50, as seen in Figure 2A. As the gel 46 contracts on cooling, the resilience of the cone 34A, and in particular of its leading edge 52 acts on the gel so as to maintain its sealing pressure around the various ~ of the joint. Thus, the fortna~ion of voids around the joint ~ in the electrically highly-stressed areas between the two ,~ i~ly disposed stress cones 34A and 36A (the latter not being shown) at each end of the joint is prevented, since sufficient pressure is maintained on the gel 46 under all conditions. It is to be noted that the ~ k ~ of the leading edge 52 of the stress cone 34A is arranged, by suitable positioning of the void 50, to take place at a radial distance outwardly of the cable 2 such that control of ~he electric field at the cm-back end of the screen 14 is not dinninished, at least not to any significant extent.
Figure 3 shows a further modifed stress cone 34B located within the housing 40, in which an aperture 60 at a radially-outward extremity of the cone is closed to entry of the gel 46 by a plunger 62 that is biassed outwardly by a spring 64. Thus, as gel 46 expands, the pressure e~cened on the plunger 62 forces it into the aperture 60 against the force of the spring 64, and on relaxation of the gel 46, the restoring force of the spring 64 mairmains pressure on the gel 46 so as to prevent the formation of any undesirable voids in electrically-vulnerable areas of the joint.
Figures 4 and 4A show another c ~ l of a stress-relief cone arranged to ~ - expansion of the gel in a joint configured generally as shown in Figure 1. The resilient cone 34C of these Figures is mounted within the outer housing 40 and has an aperture 70 adjacent to the rnner wall thereof. The aperture 70 is open to rcceive gel 46 and SUBSTITUTE StlEET (RIJLE 25) wo g6,02079 ~ ~ ~ 4 2 3 0 PcTrGBgs/0l623 to allow access of the gel to the interior of the cone bounded at its rear end, that is to say the end away from the crimp region of the joint, by a wall portion 72 acting as a diaphragm of an expansion chamber 74. In opera~ion, therefore, increase in volume of the gei 46 exerts a pressure through the aperture 70 on to the diaphragm 72, which stretches accordingly, and which tends to return to its natural un-stretched state on relaxation of the gel.
The modifled joint ~..".1;~,... A~;l~l. of Figures S and SA shows a stress cone 34D
provided with a cyiindrical tubular extension 80 at its front end terminating in a lip 82 secured in the inner waLi of the housing 40D. The housing 40D is domed partway around its ; in the region of the cone extension 80 so as to form a cavity 84 with the extension 80 mounted as a flexible diaphragrm thereacross. Increase in volume of the gel 46 within the joint thus urges the extension 80 locally to stretch into the cavity 84. Continuous pressure is thus maintained on the gel 46 as ~ u~ variation leads to its increase or decrease in volume. As shown in Figure 5A, the cavity 84 is vented by a channel 86 to a region behind the cone 34D so as to prevent build up of a vacuum. As can be seen from Figure SA, the expansion cavity 84 extends only partway around the ci.,,ull~.,l...l.,e of each of the haif shells 38D, 40D of the housing in order to allow for peripheral sealing of the half-shells of the joint by the gel contained therein. The portion 80, which as shown is an integral extension of the stress cone 34D but which may be a separate component, is bonded directiy so the housing 38D, 40D along each l ~c;~ i edge thereof where the rwo haif-shells mate, in order to prevent air being trapped between the portion 80 and the housing.
In a "..,.~ ;l-.. of the concept of Figure S and SA, the housing 38, 40 is not domed to define a cavity such as 84, but continues as a straight cylinder over and in contact with tbe diaphragm portion 80. In this . u..~ 1l, the extended portion 80, which may be a component separate from the stress cone 34, 36, is not borLded to the overlying housing except along the I a"i~ " ' edges as mentioned above. ';i'hus, when the gel 46 contracts, the portion 80, under the action of air pressur.e through the vent 86, follows the movement of the gel towards the centre of the joint, moving away from the irmer waLI of the housmg as it does so. It is envisaged that the component 80 may comprise a liner extending completely lnngim iinAlly of the joint, and in this ~llliJO iill~.a, it will be also bonded so the housing 38, 40 in the region :.~.lU~-lldilll2 the Faraday Cage 28, 30 to mamtain the electrical geometry of the joint in this region.
Figure 6 shows part of one half of a joint 600 that combines concepts from the of Figures 3 and 4. The enclosing half-shell 602 of the joimt 6iiO has a extending channel 604 in its outer wail extending aiong substantially its whole SUBSTITUTE SHEET ~RULE 26) W0 96~02079 ~ , P~ 6Z3 f'~ 1 9~230 length at one ~,h~ ~ ' ' location. A sprmg 606 and plunger 608 are rctaineti in each half (only one of which is shown) of the length of the channel 6W. A substantially rigid half stress cone 610 is located within the balf shell 602 and has a channel 612 in hs outer surface that extends from the front end of the cone 610 facing the gel fillmg 614 of the joint to the rear of the cone 610 and tbat is in . with the housmg channel 6W. Gel 614 can thus flow through the channei 612 between the cone 610 and the housing 602. enter the housing channel 6W and thus act on or be acted upon by the spring-biassed plunger 608, in order to a. ~.. ,.. 1-~ d~ .... 1 or expansion of the gel.
The still further modified stress cone 34E of Figures 7, 7A and 7B is provided with a modifled diaphragm feature oescribed above with respect to Figures S and SA, together witb certain range-taking features. Thus, the cone 34E has an apera re 90 (Figures 7A and 7B) at its front, gel-facing conical suriace, as can be seen particularly in Figure 7A showing a section tbrough the cone. Gel 46 (not shown) enters through the aperture 90 and may exert a force on the outer surface of the stress cone, acting as a diaphragm 92 to extend into a cavity formed in the housing (not shown) in a manner analogous to that described with reference to Figures 5 and SA, but with the cavity fonned in tha[ part of the housing enclosing the body of the cone 34E. Alternatively, or additionally, the rear surface 94 of the aperture 90 can act as a diaphragm in a marmer analogous to tbat described with reference to Figures 4 and 4A.
The stress cone 34E bas in addition. range -taking fearures that allow it to be used with cables of various diameters, within a given range. Thus, the stress cone 34E has three apertures 96, 98, 100 therein, vented to its rear surface (Figures 7 and 7A), definmg two channels 102, lW fh".d-.,... that extend u~ clJ into the cone anfi 1~, _ " Iy partly thereinto from the rear surface. The operation of the range-taking ability of the case 34E, and its co-operation with the outer housing, are described hereafter with reference to Figures 9 and 10.
The rlllilO,I;.,.. ~ :- discussed above allow for extenslon of the volurne of the gel 46 m the joint as it increases its ~ C, either due to increase m the temperature of the enclosed cable in operation, andlor due to increasing ambient tclllf~,la~c around the outer housing 40. However, since in the usual condition of the joint, that is to say, for the greater part of its lifetime, the gel 46 will be hot amd thus expanded, it is also envisaged that . may instead be made for contr~tion under certam conditions, such as for example when the power through the cables is interrupted. The gel- ' l ' , in so far as it relies upon movement of a resilient member, may then be SVBSTIIUTE SHEET lRULE 261 ~ wo96/02079 2 1 94~3~ 623 arranged so as to be in its relaxed condition whilst the gel is extended, and be arranged to stretch upon cooling and reduction in volume of the gel, thereby to maintain pressure on the gel. Figure 8 shows an f~ ; 1 '1 of such an ,.~ , in which the stress-relief cone 34F has an aperture 110 locally at its outer l,il~.UlllE~ adjacent the housing wall 60F.
The housing 60F has a cut-out portion 112 adiacent the aperture 110 but is separated therefrom by a flexible membrane 114 secured thereacross . The cut-out 112 is vented to the rear of the stress cone 34F. The membrane 114 and its securement to the housing 60F is arranged such that under normal operating conditions of the joint, the expanded gel 46 fills tbe aperture llO and the diaphragm 114 ;s in its relaxed state. Upon cooling, amd thus contraction of the gel 46, the diaphragm 114 is urged by excess air pressure from the venting chamber (not shown) to stretch, to extend into the aperture 110, and to adopt the position shown m dotted outline, and thus to maintain pressure on the gel 46.
It will be appreciated that the concept described with reference to Figure 8 could be applied to'o~her ,.. l, ~ for example that described with reference to Figures 5 and 5A.
Figures 9 and l O show ~ ,o~ of a range-taking dl l~.~ .,... for providing aseal on to one of number elongate substrates of various diameters, ~Y~uriifi~d by being applied to a stress-relief cone for use, for example, in the joint of Figure l. A housing 160 is of a relatively rigid, conductive polymeric, POIY"I~IJY~ " material, and is in the form of two generally-cylmdrical half-shells (only one of which is shown). At each end. the housing 160 is provided with two ~ub~4llLi~lly parallel and inwardly-directed planar projections or fins 162 for engaging with respective stress relief cones 164, each of which is also formed as two half cones. The stress cones 164 are formed from a relatively flexible conductive rubber material and have slots 166 therein for receiving respective ones of the projections 162. As can be seen from Figure lO, when hwo such 1., . ~, l~, l.. ~ as described with reference to Figure 9 are brought together around a cable 168, the softer material of the, now fully-formed stress cone 164 will tend to stretch over the outer diameter of the cable 168 and will tend to separate along the join surface 170 of the two halves of the joint enclosure. However, the rigidihy of the projecting fins 162 extending mto the stress cone 164 on each side of the cable 168 restrain movement of the cone 164 away from the cable 168 at the mterface 170.
In the exarmple shown in Figures 9 and 10, the stress cone 164 is provided with apertures 172 in its flexible material, opening towards the rear of the conical surface, thaL is to say at its surface away from the crimp region of the joint, on each side of the slots 166, SUBSTlTUTE S5~EET (RULE 26) Wo 96/0207g PCT/Gh(l~fOI623 ~
2t, ~42~J
wbich are re-inforced in the assembled cu~lriL~ " by the fins 162. The apertures 172 enhance the ability of the inner surface of the stress cone 164 to stretch over a cable 168 so as to _ ' cables of larger si~e whilst ~ a good seal ~ l C~ uullJ at the interface 170. The central aperture 172 in particular defines an inner, semi cylindrical membrane that can be stretched aromld the cable 168, with the rigid reinforcing projections 162 urging the two halves of the cone 164 into conformity with the enclosed cable 168 at the interface 170.
It will be appreciated that tbe reinforcing h~t~ "L' ~ 11 r~ 1 of Figures 9and 10 allows conformity with elongate substrates other tban by means of using a stress-relief cone. The concept can be used for example to provide a seal around a shaft, or as a bushing where a cable, which may be of one of a number of diameters, passes through a bulkhead.
Referring to Figures 11 and 12, a half cone 800, I~l,.r;lclulc-l from a conductive rubber rnaterial, is a ~ iril ~liu" of the half cone 164 of Figures 9 and 10. It will be appreciated that. Iike tbe half cone 164, the half cone 800 has a closed front end, and rhat one half cone will be located at each end of each half shell tiut forms the closure around the cable joint (only part of one half-shell being shown in Figures 11 and 12). At the rear (as shown) of the half cone 800, a large aperture 802 extends to the closed front surface of the cone, and is radially closed by the balf shell 8W. The aperture 802 is divided into three portions by a psir of frns 806 that extend generally radially from the inner surface of the half-shell 804, in a manner srmiiar to the way in which the fins 162 e~ctend from the housing half shell 160 as shown in the ~ ~ul; .. -: of Figcre 9. The fins 806 are disposed so as, in operation, to lie ore on each side of the cable within the joint. A relatively thin wall portion 808 at the inner side of the half cone 800 is arched so as, in operation, to conform around an encloseci cable and so as to receive and guide the free, inner ends of the fins 806. As shown in Figure 11, the fins are positioned relatively close to the ~ hulin~l axis of the joint, and the length of the arched portion of the inner wail 808 of the half cone 800 is miritinised. In this position of tbe fins 806, the haif cone 800 will conform to a minunum diameter size cable ~not shown). As can be seen from Figure 12, the frns 806 have a flexibility that ailows them to splay outwards and to allow a greater length of the arched wall portion 808 to extend Ih.,lel,.,~.. In this position, the half cone 800 will conforrn to a maxrmum diameter size cable. It is to be noted that in this ell~ unl~e that of FigLire 9 and 10, the irmer half cone surface 808 is not sh etched. The presence of the fins 806, however, still ensures ~ul, .~lliolly complete conformity of the completed cone around a range of sizes of cable, without air pockets being present at the interface of the two half cones adjacent the SUSSTITUTE SHEET ~RULE 26) wo 96,020,9 ~ 1 9 4 ~ 3 ~ PCTiGB9S/01623 - t7-cable surface. It will be appreciated that the flexibility of the fins 806 is such that they are able to splay outwards around a larger diameter cable but that they are reiatively rigid with respect to the softer elastomeric material of the half cones 800.
An alternative, or additional, way of providing for expansion of the gel 46 u the joint of Figure 1, is shown with reference to Figure 13A ard also with reference to Figures 13B and 13C, each of which shows a Faraday Cage modified from that illustraoed at 28, 30 in Figure 1. Referring to Figure 13A. the two half-shells 28A, 30A are formed from flexible conductive polyrneric rnaterial, and contain three apertures 120, therein. As the gel 46 expands, the mcreased pressure is exerted on the half shells 28.4., 30A, which deform by c--~ ll of the apertures 120. Cooling of the gel leads to expansion of the volume of the apertures 120 and thus to the ."~i".~ -, e of pressure on the gel 46.
A ~ ;r~ . of the ~ L' ~ ~1 of Figure 13A is shown in Figures 13EI and 13C, in which each end of tbe half-shells 28B and 30B is sealed on to the cable dielectrics 18, 20 so as to defule two apertures 122 located withtn the Faraday Cage 28B, 3ûB around the criunped conductors. As shown in Figure i3C, the apertures 122 r~ an mcrease of gei pressure by inward flexing of the half-shells 28B, 30B upon expansion of the gel 46.
Figures 14 and 15 disclose two ., I.o.l;., ~1' of the joint concept of Figure I in which change of volume of the sealant material 46 is: ~~ ~ ' ' by a ,"-- I r~ ., of the .~1, of the outer housing 40.
In the ~ ,I,o.l;.... l of Figure 14, the generally rigid outer housmg 40C is provided as part of its surface with flexible wail 130 that is subject to the pressure of the gel 46 ~not shown) contamed therein. To complete the rigidity of the housing 40C overall which may, in operation, be buried in the ground, a rigid cover 132 is arranged to fit over the flexible wali 130 to defme a cavity therewith. A resilient block 134 of rubber is located within the cavity. Thus, on expansion of the gel 46, the flexible wall 130 will transmit the pressure into C~ LIL,~IeL~ of the bloclc 134 against the restraint of the rigid housing 40C, and on rC~nrt~r~ n the wall 130 will maintain pressure on the gel so as to prevent formafion of voids around the joint.
The ,'~ of Figure lS is arranged to achieve the same effect as that of Figure 14, but to this end each half of the housing 40D is made of a rubber material and has a L,il,~UllllrL,lCllLidi portion 140 of thinner section adjacent the stress cone 142 so as SUBSTITUTE SHL~T ~RULE 26) wo 96102079 pcrlGss5lol623 2 "~
~s idlly to expand, ' any increase in gel volume, and to exert a restoring force thereon.
Referring to Figures 16, 17 and 18 an elongate semi-cylindrical integral rubber moulding 1000 has a relativeiy tifin wall ill~l '' section 1002 ~Figure 17) and a pair of relatively thick wail end sections 1004 that have a half-stress cone 1006 formed on the inside thereof (Figure 18). The moulding 1000 is arranged to be fitted into a rigid plastic outer case 1008 that is radially spaced therefrom aiong at least part of the i ' section 1002. D~ --- a or expansion of the gel filling material within the moulding 1000 results in flexing of the i ,~ section 1002 into the expansion chamber provided by the outer case. preferably fonned trom a pair of half-shells, of the completed joina The rigid intemal support members 150,160 discussed hereinafter with respect to Figures 21, 22 and 22.4, may be integrated into the rubber mouldmg 1000 and located by snap-fitting into the outer plastic case.
Refenring to Figures 19 and 20, two cables 1140 and 1142 are sho vn schemically ~ jointed at 1144. A ~, lA jJ.:l~lUII i elastomeric insulating body 1146 has fingers 1148 at each end thereof than can be tapered down to confonm with the reduced diameter of the cables 1140, 1142 on each side of the joint region 1144. One cylindrical closure member 1150 is initially rolled on to each of the cables 1140, 1142. The closure members 1150 are formed from conductive rubber.
Figure 20 shows the joint partially completed. The insulating body 1146. which rnay comprise a mating pair of half-shells rather than being of the wraparound Cl/~ ,ri,! " Al i~ ~11 as shown. encloses insulating gel material 1152 and may also contain solid insuiation enclosing the gel sealant. The body 1146 is closed around the joint 1144 amd the fingers 1148 brought down on the cables 1140, 1142. One conductive closure member 1150 is shown as having been uncurled from its parked position on the cable 1140, so as to e~tend to just more than halfway across the body 1146. The other, still-parked closure member 1150 on cable 1142 wiLI then be uncurled so as to overlap the first closure member. In this way, the insulating body 1146 including both its fingered end-sections 1148, and the entire cable joint region is enclosed within the two conductive outer members 1150.
Figures 21, ~2 and 22A disclose ell-L " of cable joint in which a conductive component such as a Faraday Cage, can be supported within the joint whetl it is otherwise SUBSTITUTE SHEET (RULE 2B) ~ WO 96/02079 2 1 9 ~ ~ 3 ~ PCT/GB95/01623 enclosed by non-rigid material, and in particular can be positively located with respect to an outer conductive housimg.
In Figure 21, the arcuate Faraday Cage 28c is made of conductive polymeric material, is disposed in silicone gel sealant 46 as h..c,...v.,fulc, described, is radially spaced (by means not shown) from the enclosed crimped conductors (not shown), and is located axially between stress cones 34G and 36G. These '"~ ~ ~'~ are enclosed within the outer housing 40 of ' ~ly - filled pol,yl.lu~lul..,. Under certain conditions, and especially when the ~ lu~ .C of the gel 46 is increased~ there is a likelihood that the conductive cage 28c could move laterally within the gel 46 towards d1e housing 40, which is at earth potential, and thus forrn a short circuit from the high voltage of the cable conductors. In this C;lllbUllilll_l~i, movement of the cage 28C is pre~ented by employing an insulating polymeric support cradle or spacer 1~0. The cradle 150 is arcuate and mounted in the anmular gap between the cage 28C and the housing 40, and, like those r~ ,u. ."~, is formed as two half-shells. Fach half of the spacer 1~0 is provided with a series of projections on each of its curved surfaces so as to distance it from both the cage 28C and the housing 40, thereby to allow gel 46 ~uL~ completely to fill the space ~ lUUIId.
The spacer 150 is arranged to provide good physical i..t~,.c v v witn both the cage 28C and the housing 40, for example by means of ;m~ .g projections and apertures andlor a snap-fitting m~rh--:-m thereby securely to maintain the conductive cage 28c in position both radhlly and l. ~ ly within the joint.
Figures 22 and 22A show another variation of support member for use with a Faraday Cage. Referring to these Figures. the polymeric insulating support member 160 is of partial semi- cylindrical ~ . being flanged at each end so as to provide for an annular chamel 162 between the support 16Q and the outer housing 60 when used inoperation to support the Faraday Cage 28. As shown in Figure 22A, which is a section through one of the half-shell ~ of the joint, the Faraday Cage 28 and housing 60 are fully semi-cylindrical so that when brought together v.~ith the ~.l..r~l... l:- ;~ half-shell around the crrmped conductors (not shown), the cylindrical surfaces thereof are completed.
The two half shells of the support member (only the one 160, being shown) however ex[end for less than 180 degrees, with the region tL.el,~.-.".,." as well as the channel 162, being filled by the gel 46, to provide a gellgel radial interface between the Faraday Cage 28 and the housmg 60 on closure of the two half shells around the crimp region. The support member 16Q may be mr~rh~nir~lly inrrrlr~rkrrl as described with reference to thermhorlimrn- of Figure 21 for example, with both the Faraday Cage 28 and the housing 40 of its respective half shell so as securely to locate the Faraday Cage 28 within the joint.
SUESTITUTE SHEET (RULE 26) WO 9~1U20n rC'iL'~G119~ilO1623 ~1 ~At.~
The support spacers 150, 160 may but need not extend Ir~n~ituriin~lly CO .~lugullJu.~Iy with the associated Faraday Cage.
In a further l~u~l;ri~ ", it is envisaged that the support member may be mouldedintegrally with the Faraday Cage andlor the housing. In such a cv1~LIuuLiOu, the rnoulding operation itself may exclude air from the moulded surface of the support member, thus avoiding the need to allow the gel 46 to have access to any interface between the support member and the Faraday Cage and/or housing.
Figures 23 and 23A show two different ",..ri~ ",~i,. . by which the lrmgihlrli edges of the two half shells of the housing of a cable joint can be imerlocked. In each case~
one edge 180,180A is provided with a groove 182,182A extending therealong, being of trapezoidal section in Figure 23 aDd of key-hole section in Figure 23A. The grooves 182,1S2A are filled with gel, al~c,l~6.,u_~ly the same as that providing the bulk insulation of the joint. The opposing edges 184,184A of the housing are provided with uullc~l~u..1ul~ly-shaped projections 186,186A. Upon closure of the two half shells of the housing around the electrical connection, the projection 186,186A engages the associated groove 182,182A, and the gel forms a seal Lh~lcl~
Referring to Figure 23B, a cross-section is shown of a jointed cable 5r~hr~m~rir ~lly at 200 partially embedded in gel 202 that is contained in each part of a pair of half-shells 204, 206. The half-shells 204, 206 are substantially semi-cylindrical and are hirged together at 208 along one pair of longih-ri;n~l edges. The hinged cylindrical housing forrned by the two half-shells is closed around the jointed cables and Figure 23B tepresents the situation just prior lo closure of the housing. The l ~' " ' edges of the half-shells 204, 206 opposite the hirge 208 are provided with a co-operating tongue 210 and groove 212 ~
along the ma3Or part of the length of the housing w hich contains the gel 202 that is to be urged into conformity around the enclosed jointed cables. The tongue 210 ls of such a length, in the .i.~ ~ -5 .c,,~ direction, that on closure of the two half-shell 204, 206, il engages the groove 212 before pressure on the gel 202 is sufficient to exude it sideways out of the housing. In this way, all the gel 202 is cornpletely contained within the closed housiog ~,h~u~uf~lcuficlly, thus avoiding any possible shearing of the gel that could .,_b~ ..uLly lead to the creation of voids within the housing.
SUBSTITUTE SHEET (RULE 26 WO 96102079 ~ 5 0 PCT/GB95/01623 Positive locicing together of the two half-shells 204, 206, is achieved by a plurality of discrete projections 214 along the outer surface of the tongue 210 which snap into co-operating apertures 216 in the outer wall of the groove 212.
Sealing of the housing against ingress of moisture, air, dust or other ~ ' aroumd its periphery at the mterface of the two half-shells 204, 206 is enhanced by the provision of a ridge 218 around the entire periphery of the half-shell 206 that tightly engages with a mating peripheral depression 220 in the half-shell 204.
Finally, the two half-shelis may be secured together by toggle clips or other suitable fastening means applied externally of the closed housmg.
Referring to Figure 24, a joint between two screened cables 1160, 1162 is enclosed within a two-part housing 1164. A slot 1166 is cut axiai iy into the housing 1164 at each end thereofml.,.,~ ;"Alalignment,andtilescreenwiresll68,11700fthecablesll60,1162 .-,.,t,..~i~.ly are brought out through the slots 1166 and crimped together at 1172 over the outer housimg surface. The connecting together of the screen wires 1168, 1170 and their : ~ _ witbin the slots 1166 in this mannel-, prevents the housing 1164 from moving either rotationaily or l-~ngjh~ ly with respect to the jointed cables.
Referrmg to Figure 25, the housing 1180 is formed from two semi-cylindricai half-shells that are hinged together at 1182 aiong its central portion, and that are sealed by a tongue and groove Al I"'~L~ 1 around their rnating peripheries. Beyond a tapered portion towards each end of the housing 1180, a cylindrical portion 1186 is forrned between a pair of ribs 1188thatextendaroundthel,h~ r c~eofthehousmg. Thehousing 1180is secured on to the enclosed jointed cables by means of tape, a tie-wrap, a roll-sprmg or the like 1190 that is wrapped around the cylindrical housing portions 1186. To enhance the sealing, and to assist the retention, of tne housing on the cables. mastic or other sealant materiai may be located between the housing portions 1186 and the underlying cable jackets.
The seaiant rnaterial may be appiied to the cables as a wrappmg, or may be retained by the housing 1180.
SUEST~TUTE SHEET (R~LE 26
This invention relates to the protection of electrical i..:- ~ . "." ~ Such i..;...u,....,.liu.~ may be between two or more electrical cables (i.e. in-line or branch joints), between two or more pieces of other electrical equipment such as ~. DrulL~ and switchgear, but which may also include anodher cable or between cable and equipment, includhng cable adapters and t. . ,ll; ~ Such an hl;~lcolLI~.,Liull usually needs to be protected against ingress of moisture IO h.:.l.ulL~.t d conductors, and to provide electrical insuiation li...~., ' Additionally, at voltages above about 10kV, some form of electrical stress control is usually also desired. The invention is generally applicable to electrical Lli~lCUIhl~liUIID at lûw voltage, typically aro~und I to 10kV, at medium voltage, typically around 10 to 36kV, and also at high voltage, typically greater than 36kV.
Various ~ exist for protecti.ng such i..t~", . ." l i. " ,~ some of which are more applicable to one voltage range rather dIan another, and some applicable to cables, for example, of one material, for example polymeric, then anodher, for example paper.
Amongst these t~ l ~Ir,~;. s may be mentioned polymeric heat shrink. elastomeric push -on and roll-on, elastomeric hold-out. tape windmg, hot bitumen filling, and cold-pour resin systems. Pending Raychem US Patent Applicatiùn Serial Number 081138360, the contents of which are now published in l,.~ i"" l Application Publication No. WO 95/11543, discloses a power cable joint which is flled by a Cull~ D~;l/le sealant material such as gel, which has been found to have ~u~ h~ly good p...u....~...
The present invention is particularly concerned widh an h~ between an electric cable and other electrical equipment in which a cu~ lc~i,,lc, and preferably oil-extended polymeric, sealant materiai is employed to seal and to provide electrical insulation around the connection.
Thus, in accordance with one aspect of the present invention, there is proi ided an enclosure arranged to enclose a connection between a screened electric power cable and anodher piece of electrical equipment, the enclosure comprising a housing, at least one ~ electrical stress cone contained widlin the housing, and a quantity of cu~u~,.,.;bl~ sealant material that is contained by the housing and that Du1~KIllLi.llly fills the housing when ~ encloshng the ill.~.CUlhl~ , wherein dhe or each stress cone comprises resilient aperture means dlat is arranged to change its volume in response to a change of volume of the sealant material thereby, in operation, to maintain substantially complete ftiling of the housing around dhe Ll~ ullu~Liull widhout the formation of voids therein.
SUESTITUTE SHEET (RULE 26) WO 96102079 : PCT/GB95101623 2194?3~ ~
The resilient aperture can thus adapt to the volume of the sealant material as it changes in 2~sponse to change in tVlll~ di~ of the substrate or of its amhient au~Luulldillo~
or to other external pressure. The sealant material al~dl.LO~,Jualy adheres to the resilient means so as to minimise the likelihood of a void forming as a result of movement of the material.
The aperture means may expand, or stretch, as the sealant expands, or it may be arranged to be in a relaxed cullBo~.dliùu when the sealant is in its expamded state. which is expected to be the state it occupies most of its time in operation.
In many ~ of the present invention, it is dd~ o~u~l~ for the resilient aperture means ~o exert a continuous pressure on the sealant material. Howe~er, when t,he sealamt material comprises a ~ ", of solid and a liquid component, such as a gel comprising an oil-filled polymer for example. the pressure should not be such as Io urge the liquid component ~io~drl~d~l-ly out of the complete system.
The aperture means may be provided by a vaid or gaseous entrapment contained completely within a resilient portion of the stress cone, or located between a resilient portion of the cone and a non-resilient portion of the housing.
A spring and plunger 2 v may be provided ro as to prevent the forrnation of voids in the h~ ul~l-~Liull. Alternatively, a resilient wall may be arranged as a diaphragm to exert, or to maintain, pressure on the sealant material.
The sealing is typically required to provide a block to the passage of air, moisture, or other fluids.
The sealmg material of the invention may geneMlly comprise any cu.~ c~aiv~.
sealing material, e.g. mastic or grease (especially a highly viscoug grease such as a silicone grease). Preferably, however, the sealing material comprises cured gel.
The gel may, for example, comprise silicone gel, urea gel, SEBS, SBS, di- and tri-block copolymers and blends thereof~ urethane gel, or any suitable gel or gelloid sealing material. Preicrred gels comprise oil - extended polymer ~ Preferably the gel has a hardness at room i , c as determmed usmg a Stevens-Voland Texture Analyserof greater than 48g, particularly greater than 14g especially greater than 18g, e.g. between ~aULSTlTUTE SHEET ~RULE 26) W0 96/02079 21 9 4 ~ 0 PCTIGB9~/01623 18g and 29g. The test settings of the Analyser should be: speed = 0.2mrnJsec; penetration = 4mm; and sphere diameter = 0.25 inch. It preferably has a stress-relaxation less than 609'o, particularly less [han 50% and especially less than 40% and preferably grea~er than 10%. Ultimate elongation, also at room t~ ,lalulc, is preferably greater than 100%, especially greater than 200%, ~ u~ iy greater than 400%, as determined according to ASTM D638. Tensile modulus at 100% straim is preferably al least 1.8 MPa more preferably at least 2.2 ~IPa. In general cv.lll~lc,~iu-l set will be less than 25~o, especially less than 15~o. Preferably, the pel has a cone penetration as measured by AST~vi ~217 of at least 50 (lO~1mrn), more preferably at least 100 (lO~1mm), even more preferably at least 200 (lO~Imm) and preferably no greater than 400 (lO~Irnm), especially no greater than 350 (10-1mm). Reference is also made to US Patent No. 4852646, especially Figure 3 thereof, for alternative gel parameters., showing the l.,l~tiol.,l i~ between the Voland Hardness and the Cone Penetraion value, the entire contents of which are included herein by tilis reference. Also, reference is made to tne suitable materials disclosed in US Paten~ No.
5079300, the entire contents of which are included herein by this reference.
Aiternatively, the polymer e. ", ~ , of the gel may for example comp}ise an eiastomer, or a block copolymer having relatively hard blocks and relatively soft elastomeric blocks. Examples of such copolymers inciude styrene-diene block copolymers, for example styrene-butadiene or styrene-isoprene diblock or triblock copolymers, or styrene-ethylene-butylene-styrene triblock copolymers as disclosed in i ~ l patent publication number W088/00603. Preferably, however, the polymer Collll)u~;~iull comprises one or more styrene~ethylene-l,.u!,yl~ styrene block copolymers, for example as sold under the Trade Mark 'Septon' by Kuraray of Japan. Septon 2006 is a particularly preferred grade. The extender liquids employed in the gel pre~erably comprise oils coll~,l.dul~lly used to extend elastomeric materials. The oils may be h~ GIbUII oils, ~or example paraffinic ornaphthenic oils, synthectic oils for example polybutene or puly~JIutJ~ oils, and mixtures thereof. The preferred oils are mixtures of non-aromatic paraffins and naphthenic h.1llul,albull oils. The gel may contain kno-vn additives such as moisture scavengers (eg.
Benzoyl chioride), -~ i.t ,~, pigments and fungicides.
The gel used in the present invention adv.ulL~ ,u~.~ly has a dielcctric breakdown strengtn of at least 18 KV/mrn, preferably greater than 24 :KV/mm, being in tne preferred ~ range of 24 to 50 KV/mm, but could even be as high as 100 KV/mm. These vaiues apply not oniy to the bulk values of tne gel itself, but also to any mterface between the gel and other materials with which it has contact in the ;,.~., ' The preferred gel material comprises a silicone gel, being a silicone polymer extended with an inert siiicone oil.
SUBSTITUTE SHEET ~RULE 26) WO 96/020~9 r~ '7~
21 9~30 It will be undersLood from tbis document that the term ~culllul~a~il/l~" in the context of the sealant material reFers tu a material that. upon being subject tu an external pres.sure. is cvl~ caaibk so as to flow around an enclosed substrate. The pressure may arise from the housmg that contains tae sealant material being applied to, for example closed around, the electrical; ~ u ~ or from thermal expansion of the sealant material. With the preferred sealant material being a gel, the ~:u---,u-c~ c force resuls in ~ ,,. andlor p ~ that allows substantially complete conformity with the substrate, which confornnity can be maintained even under thermal cyclimg.
The connection will typically be of substantially cylindrical ~ i;lll The present invention is of particular dl~l/l;.db;li~y in connections in which the housing consiss of two, or more, inter-engaging ~ullluull.llLa, for example two half-shells. In such a cullrl~uldiiull, the stress cone is also ad~dllLd~,~,uualy formed of a plurality of uuul,uù~m~, for example two half-cones taat mate on closure of the housing, so that tae iUIL~I~
caLn c()~ ,.ily be formed in a rldj~dlUUllPi manner around the already-made electrical comnection, for example a crimp. Conveniently, the gel sealant is supplied as a filling contained within each part of the housing, which then seals the interf~e Lh,_.cb..~ The advamtages of this cu~ . .dlioa, especially when using a gel as the sealant, are discussed in pending Raychem US Patent Application ~Serial Number 081138360 (WO 95111543), the entire contents of which are included herein by this reference. In particular, the A ' ' "ly high dielectric strength found at the interface of the two portions of the gel, and ihe excellent adhesion of the gel to the ~ of the L t l-UlUl~iiUII, such as the cable materials ~usually pul,~,;i-yl-,.. or l~ul~vi--~lid~ chioride), substantialiy prevent air pockets to exist iil~lCh~ ll and allow a cable joint, for example, to he made of a much-reduced length than has previously been possible. A shorter length joint requires less cable preparation, and ti-ius less time to complete, this being particularly so when the cable system is buried in the ground.
The housmg used in the invention, preferably formed from two inter-engaging halfshells, is preferably made of a conductive polymeric material, having a volume resistivity of the order 10' ohm-cm. A~ ,gr..~ its material is carbon-filled i u.~,u.u,u,~i. ..c.
Alternatively, the housing may have an insulating imner component and a conductive outer component, to provide the required screening function. As othcr options for the housing, there may be mentioned a push-on dlldLc~_ ~. i that is stretched over the ;~ - o .... or a revolving sleeve as disclosed in US Patent Number 4868~,67. The housing that seals the electrical hl.~ .Liu.. dd~GlllAb_UU:lly has at least a portion of a wall thereof that is subject to the pressure of the sealant material formed so as to flex m order to: ' SUBSTITUTE SHEET (Rl!LE 26) wosc~o2079 21 ~3~ p ,,~ 623 change of volume of the sealant material. The resilient wall section may be bounded externally by a non-resilient wall portion so as to defme a ~i~r~ Pnn~nl cavity ~ ,v~
which cavity may contain resilient means. It is also envisaged that a major part of the housing surface (ie >50~0), and adval~ v~..ly ~ Dia.l.idlly the whole of that part of the surface that p.,li~L~Ia:l~ encloses the sealant material, is resilient. The housing may be deformable such that it is able to change from a cross-section of one shape to a cross-section of a different shape that encloses a larger volume. For example, the housing may be arranged to change from a generally oval to a substantially circular cross-section.
In order to contain the sealant material, ,udlLi-.h all~ though not exclusively when it is a material such as an oil-extended polymer, when it is subject to a cv~ ul~ , force on closing Lh~l~,alvullll of a housing, formed from two half-shells for example, it is preferred that the closing edges of the housing overlap before final closure takes place, and thus before significant ~ . ., pressure is exerted on the sealanL material, In the case of two nngih~rlin~ y-extending half-shells, for example, a projection along the l-~ngih~in~l edge of one half may engage a channel along the other edge. The sealant material is thusr C llfldlly contained within the closing housing before sufficient pressure is exerted on the sealant material to exude it laterally out of the housmg.
Means may be provided to restrain movement of the housing rotationally and/or Inn~ihl~:in~ y with respect to its substrate, which may be an electrical hlL.,Iuu...~,.Liuu for example.
A flexible part of the closed housing, ûr of another component within the joint that is subject to, and contains the pressure of, the sealant material, may be arranged such that the flexible portion follows any conhraction of the sealant material so as to avoid the formation of any pockeLs of air.
The Faraday Cage member is preferably of a conductive ~ material of similar resistivity to that of the conductive housmg, but it may -' ' r~,ly be formed of metal or metallised plastics material. The conductive Faraday Cage member is ad~ v..~.ly resilient so as to exert pressure on the sealant material, thereby ~ub~L,~uliall~
to prevent the formation of voids within the housing outside the conductive member contained thereim. Preferably, the conductive member has at least one void or gaseûus entrapment completely contained therewithin that is subject to the pressure of the sealant material. The support cradle for the Faraday Cage is preferably formed of an insulating ~h.. ~ ' material. The support member can ~uu.. llLly be secured to the housing so SUBSTITUTE SHEET (RULE 26~
wo 96102079 pcrlGs9slol623 't~4~3~ /~
as posi~ively to locate the conductive Faraday Cage member within the flo~able sealant materiai.
The stress cone used in the invention may be made of a conductive rubber or elastomeric material, EPDM for example, typically of volume resistivity 103 ohm-cm.
The enclosure may comprise a seaiing member, acting as a stress-relief cone for example and the sealing member a.l~...lL~,cuu~ly comprises (a) a relati~ely rigid component and (b) a relatively resilient component, which may haYe at least one aperture therein. The relativeiy rigid component is arranged to urge the relatively resiiient component in20 substantially complete conformity around the substrate, and the seaiing member is thus able to: ' a range of substrates, electric power cables for exarnple, of different sizes, usually diameters, whilst ~ a good, substantially void-free seal therearound.
It is to be understood that the materials of each of the ~ used in the invention are to be selected so as to be compatible with any component with which they come into contact and so as not to have any adverse reaction therewith, especially over longer time periods.
In accordance with another aspect of the present invention, there is provided anillt'_l~,U~,~iUIl between a electric cable and another piece of electricai equipmenn the ,ICo~.,~iu.l bemg enclosed within an enclosure in accordance with the first aspect of the mYemion.
The other piece of electrical equipment may be, for example, another elec2rical cable, or equipment such as switchgear or a L~dll,ru.ll~ to which the said cable is connected, or other equipment at which the said cable is terminated.
Enclosures and hlLI.~ in accordance with the present invention are hereinafter described especially ~ith reference to Figures 1 to 6 and Figure 8 of the a~cu~ l.riu~ drawings but it is envisaged that features of other Figures may also be included in such enclosures or illa~ "'. for example, the features associated with the Faraday Cage ~Figures I and 13), the housing (Figures l, 6, 14 to 20 and 23 to 25).
Fu~ ulc, the present invention may aiso encompass the Faraday Cage suppor2 features (cAcull~lir~l in Figures 21 and 22), and may employ a range-taicing seaiing member (as exemplifled in Figures I, 7 and 9 to 12). Some of these fearures are the subject of aur SUBSTITUTE SHEET !~ULE Z8?
WO 9610tO79 2 1 9 4 2 ~ ~ PCT/GB9S10 1623 patent ~pplir~ti~ m filed l Vll . ~ JUl~ OU~ly herewith, under our references RiC503, RK505 and RK506, the entire disclosures of which are i~u~Jv~lL~d herein by this reference.
SUBSTITUTE S~ EET (RULE 26) WO 96/02079 PCT'/GBgW1623 '~J,1 qL~23;') - S -F." ,1 u ~ of the present invention will now be described, by way of ex~unple, with reference to the a ~~ yhlg drawings, in which:
ure I shows crhr~m~irrlly a cross-sectional elevation of an in-line joint between two screened lSkV power cable joints, foml~ B~ the general principles of theinvention;
Fi,~rPc 2. '~ show crhPm~-~ir~lly a first P..lllr)r~ of the invention in which astress-relief cone of the joint of Figure I is arranged to - ' expansion of sealant material of the joint;
Fi~ure ~ shows another fonn of stress cone to that of Figure 2;
Fi~nrPc 4~ 4A show still ;mother form of stress cone, in section and in isometric view ~ .,;y, Fiel~r-~ 5~ 5A show another variation of the cable joint of Figure 1, in which sealant ~ expansion is ~ in section and in isometric view r~ d~ly;
Ei~i shows a partial section through one half of a modifed joint:
h~Q shows another form of stress cone for use with the joint of Figure l;
Fi~ure 7~ shows a cutaway view of the stress cone of Figure 7;
Fieure 713 shows a reverse angle isomctric view of the stress cone of Figure 7;
~ shows a further ..,..B;li. ~ of a str~s cone for ~ sealant expansion within the joint of Figure l;
Fieure 9 shows a dis-assembled view of one half of a modified i~ of outerhousing and sLress-relief cones for use in the general joint C~ Llu,Liull of E'igure l;
Fieure ID shows a cross-section through a completed joint employing a stress cone as shown in Figure 9;
SUBSTITUTE SHEET ~F~ULE 26) WO g6102079 ~ 1 9 4 ~ 3 ~ PC'T/GBgSlOlG23 ..9 Fi~lr~c 11 an i 1?. are isometric views of the rear end of one half of a modified range-taking stress cone;
Fi~-rr~ 1 ~A. l ~B an(l l ~C illustrate ~ lly features applicable to the Faraday Cage of the joint of Figure 1 for ~r~ expansion of t. e sealant material of the joint;
Ei~lg shows crh~ m~rir*tly one n"~ l;r~ ; of the housing of the joint of Figure I for ~ ~ ~ ", .~ i . .o expansion of the sealant material;
Fieure 15 shows a furiher ",(,.I;r~ o~ of the housing of Figure 1:
EiE~l~ shows an isometric view of one half of a further . - --).1;1;, ~1 ;l ~ l in w hich an integral insert provides for gel expansion and includes stress cones;
Fi~l~rpc 17 ~nri 18 show sections along lines B-B and A-A respective of Figure 16;
F~lr~ 19 :m(l 20 ~ lI,y show a ...o(liri ~ .. of the outer housing of tne joint, formed from three c~
Figure 21 shows crhrm~tir~lly one a~ .L,. .". .a in which a Faraday Cage of a cable joint may be supported when it is enclosed by non-rigid material;
Ei~~~ shows another ~ ~ ' of suppOn for a Faraday Cage;
Fir-re 21~ shows a cross section tnrough part of a joint employing tne support member of Figure 22;
F~r~r~C 2~ an~l 2~ show cllll,o~l,..l.,ll.~ in section of a seal along the l~ngin edges of tbe two half shells of tne housing of the joint;
F~re ?~ B shows a cross-section through a modified joint showing a Ir,ngi~llrii closure ~ , Ei~2~ is an isometric view of one G ~ of a completed joint; and SUBSTITUTE SHEET (RULE 26) Wo 96/02079 2 1 9 4 2 3 ~ P .i ~ .!~bl623 .
Fi,2ure 25 is a side vieu of a further ~ 1 of housing.
Referring to Edgure 1, the in-line joint is formed between two substantially identical polymeric cables 2, 4. The respective outer jackets 6, 8, screen wires 10, 12 screen layers (semi conducting or conducting) 14, 16, primary dielectric layers 18, 20, and conductors 22, 24, are ~u..~ cut back rn standard manner. with the screen wires 10, 12 being folded back o-er their respective jackets 6, 8 for subsequent i.~ l U...._~iiUII (not shownJ across the joint so as to maintain earth continuity. The conductors 22, 24 are electricaliy...L~ ,~d by means of a crimp connector 26, although any other suitable type of connector may be used. Electricai stress control of the conductor comnection thus made is provided by a member comprising two generally semi-cylindrical half shells 28, 30 made of conductive polymeric material that are brought together around the casing 26 between the two cables and which I ~, " 'iy extends a short way over the cable dielectric layers 18, 20. Each half shell 28, 30 has tbree inwardly-directed projections 32 that rnake electrical contact with the crimp 26 to ensure that the half shells 28, 30, and the conductive rnn~ n.c enclosed therewithin are maintained at the satne electrica] potential. rlamely the potential of the cable conductors. The haif sheMs 28, 30 thus provide a Faraday Cage effect around the crimp 26 and exposed conductors 22, 24. It should be noted tnat the half shells 28, 30 do not seai on to the cable dielectrics 18, 20.
Stress-relief cones 34, 36 are provided for the respective cables 2, 4 and are located so as to provide a conical surface directed away from the cut hack ends of respective sbields 14, 16 in the usuai manner. The stress cones 34, 36 are formed of a conductive rubber and are each provided as a pair of half cones for assembling around the cables 2,4 after the electrical connection ~ ,.. has been made.
The stress cones 34, 36 and Faraday Cage 28, 30, nre completely enclosed within a pair of generally semi-cylindrical outer hinged half shells 38, 40 rnade of conductive polymeric rnaterial, namely carbon-f lled polypmpylene, that fit together to form a cylindrical housing that clamps around the cables 2, 4 so as to seal do vn on to respective cable jackets 6, 8 to each side of the joint.
An electrically insulating support cradle, formed as two semi-cylindrical ~ t~
42, 44, is secured to the outer surface of the Faraday Cage 28, 30 and to the inner surface of the outer housrng 38, 40, so as positively to locate the Faraday Cage 28, 30 both l~n~ih~ y and radially within the joint and thereby to enstlre electrical isolation of the Faraday Cage from the outer housing.
SU~STITIJTE S%E~T [RULE 2~) wo g6,020,9 ~ I q 4 2 3 0 PCT/GB9Sml623 The space remaining witnin the housing 38, 40 around and within cradle 42. 44 and the Faraday Cage 28, 30, and lo~ .i;,l..lly bounded by the stress cones 34, 36, is completely filled with an electrically-insulating silicone gel 46.
The ~..).l ~pl " l " ~ of the joint are assembled by locating respective ones of the support cradle 42, 44, the Faraday Cage 28, 30 and the stress cones 34, 36 within respective housing half-shells 38, 40, pourmg the gel 46 in liquid, un-cured fortn into each half shell up to its rim, and then allowing the gel to cure. The cables 2, 4 are then prepared by being cut back, the conductors 22, 24 secured together by the crirnp 26, and insulating, stress relief and screening are then provided simply by clamping the prepared housing half shells 38, 40 Lh.L~uuulld The securing together of the half-shells 38, 40 brings together the generally planar surfaces of each portion of the gel 46, which then provides a high dielectric strength interface, not oniy gel-to-gel where the half shells meet, but also on to the enclosed y.~ of the cables 2, 4, such as the dielectrics 18,20.
As the two half shells 38, 40 are closed around the jomted cables 2, 4, the gel 46 is subjected to a l,uul~ ., force such that it flows around all of the ~ and conforms therewith. Air present around the jointed cables is thus forced away and its place taken by the deformed gel 46. It will be appreciated that before closure the gel 46 "y fills the half-shells 38,40 to their rims. Accordingly, upon closure around the jointed cables, a quantity of the gel 46 is displaced, and this has to be ~ d by the .u~LL~,du~l of the joint. F ULI~.,I111U~, thermally cyclmg of the power cables 2, 4 gives rise to expansion of the gel, which also has to be . ~ ~ ~ F "1 r~.1; ' of ~le joint disclosed hereinafter solve these problems.
Further details and features of the general ~u.._.lu~,Liuu and assembly of such a jomt are given im pending US Patent Application Serial Number 081138360 (WO 95111543) of Raychem Corporation, the entire contents of which are included herein by virtue of this reference.
The following Figures 2 to 25 show ir. further detail specific features of the cable jomt of Figure 1, and variations thereof, each m accordance with various aspects of the present invention. It is to be understood that all ~I..,.l.;" - ;.,.~ of two or more features herein described are considered as ~ ' of the present im~ention, except where such a c.. 1.;.. ~ " is obviously non-operable.
SUBSTITUTE SHEET (RULE 26) wo 96/02079 Pcr/Gss~ 623 ~11 1 q ~L f~ '' f~) Referring to Figures 2 and 2A, a stress cone 34A, in two generall~ semi-cylind.rical parts, is a ",r.~l;ri. ~, i. ", of the basically configured stress cone 34 of Figure 1. It is iormed within the housing 40 so as to define an annular void 50 therewith. The cone 34A extends away from the cdge of the screen 14 with a leading edge 52 of the cone 34A sealing on to the housing 40.
The gel 46 is seen to fill the volume within the housing 40 around the cable dielectric 18. Figure 2 shows the al.~",~ of the cable joint on mstallation, with rhe cableunpowered and cold. In operation, the cable conductor can reach operating r~ U~ of up to 95 degrees Celcius, and in some instances even higher. Under these condhion tbe gel in the joint, typically being a quantity between about 200 grams and about 300 grarns, can extend up îo 20% in volume. and with a ngid outer housing 40, the expansion bas to be d' ~ ' d within the c.,llr"--lali.", of the joint. In the present c~lJodi~ ll, expansion of the gel 46, acting OD the relatively soft rubber of the stress cone 34A is arranged to compress the v oid 50, as seen in Figure 2A. As the gel 46 contracts on cooling, the resilience of the cone 34A, and in particular of its leading edge 52 acts on the gel so as to maintain its sealing pressure around the various ~ of the joint. Thus, the fortna~ion of voids around the joint ~ in the electrically highly-stressed areas between the two ,~ i~ly disposed stress cones 34A and 36A (the latter not being shown) at each end of the joint is prevented, since sufficient pressure is maintained on the gel 46 under all conditions. It is to be noted that the ~ k ~ of the leading edge 52 of the stress cone 34A is arranged, by suitable positioning of the void 50, to take place at a radial distance outwardly of the cable 2 such that control of ~he electric field at the cm-back end of the screen 14 is not dinninished, at least not to any significant extent.
Figure 3 shows a further modifed stress cone 34B located within the housing 40, in which an aperture 60 at a radially-outward extremity of the cone is closed to entry of the gel 46 by a plunger 62 that is biassed outwardly by a spring 64. Thus, as gel 46 expands, the pressure e~cened on the plunger 62 forces it into the aperture 60 against the force of the spring 64, and on relaxation of the gel 46, the restoring force of the spring 64 mairmains pressure on the gel 46 so as to prevent the formation of any undesirable voids in electrically-vulnerable areas of the joint.
Figures 4 and 4A show another c ~ l of a stress-relief cone arranged to ~ - expansion of the gel in a joint configured generally as shown in Figure 1. The resilient cone 34C of these Figures is mounted within the outer housing 40 and has an aperture 70 adjacent to the rnner wall thereof. The aperture 70 is open to rcceive gel 46 and SUBSTITUTE StlEET (RIJLE 25) wo g6,02079 ~ ~ ~ 4 2 3 0 PcTrGBgs/0l623 to allow access of the gel to the interior of the cone bounded at its rear end, that is to say the end away from the crimp region of the joint, by a wall portion 72 acting as a diaphragm of an expansion chamber 74. In opera~ion, therefore, increase in volume of the gei 46 exerts a pressure through the aperture 70 on to the diaphragm 72, which stretches accordingly, and which tends to return to its natural un-stretched state on relaxation of the gel.
The modifled joint ~..".1;~,... A~;l~l. of Figures S and SA shows a stress cone 34D
provided with a cyiindrical tubular extension 80 at its front end terminating in a lip 82 secured in the inner waLi of the housing 40D. The housing 40D is domed partway around its ; in the region of the cone extension 80 so as to form a cavity 84 with the extension 80 mounted as a flexible diaphragrm thereacross. Increase in volume of the gel 46 within the joint thus urges the extension 80 locally to stretch into the cavity 84. Continuous pressure is thus maintained on the gel 46 as ~ u~ variation leads to its increase or decrease in volume. As shown in Figure 5A, the cavity 84 is vented by a channel 86 to a region behind the cone 34D so as to prevent build up of a vacuum. As can be seen from Figure SA, the expansion cavity 84 extends only partway around the ci.,,ull~.,l...l.,e of each of the haif shells 38D, 40D of the housing in order to allow for peripheral sealing of the half-shells of the joint by the gel contained therein. The portion 80, which as shown is an integral extension of the stress cone 34D but which may be a separate component, is bonded directiy so the housing 38D, 40D along each l ~c;~ i edge thereof where the rwo haif-shells mate, in order to prevent air being trapped between the portion 80 and the housing.
In a "..,.~ ;l-.. of the concept of Figure S and SA, the housing 38, 40 is not domed to define a cavity such as 84, but continues as a straight cylinder over and in contact with tbe diaphragm portion 80. In this . u..~ 1l, the extended portion 80, which may be a component separate from the stress cone 34, 36, is not borLded to the overlying housing except along the I a"i~ " ' edges as mentioned above. ';i'hus, when the gel 46 contracts, the portion 80, under the action of air pressur.e through the vent 86, follows the movement of the gel towards the centre of the joint, moving away from the irmer waLI of the housmg as it does so. It is envisaged that the component 80 may comprise a liner extending completely lnngim iinAlly of the joint, and in this ~llliJO iill~.a, it will be also bonded so the housing 38, 40 in the region :.~.lU~-lldilll2 the Faraday Cage 28, 30 to mamtain the electrical geometry of the joint in this region.
Figure 6 shows part of one half of a joint 600 that combines concepts from the of Figures 3 and 4. The enclosing half-shell 602 of the joimt 6iiO has a extending channel 604 in its outer wail extending aiong substantially its whole SUBSTITUTE SHEET ~RULE 26) W0 96~02079 ~ , P~ 6Z3 f'~ 1 9~230 length at one ~,h~ ~ ' ' location. A sprmg 606 and plunger 608 are rctaineti in each half (only one of which is shown) of the length of the channel 6W. A substantially rigid half stress cone 610 is located within the balf shell 602 and has a channel 612 in hs outer surface that extends from the front end of the cone 610 facing the gel fillmg 614 of the joint to the rear of the cone 610 and tbat is in . with the housmg channel 6W. Gel 614 can thus flow through the channei 612 between the cone 610 and the housing 602. enter the housing channel 6W and thus act on or be acted upon by the spring-biassed plunger 608, in order to a. ~.. ,.. 1-~ d~ .... 1 or expansion of the gel.
The still further modified stress cone 34E of Figures 7, 7A and 7B is provided with a modifled diaphragm feature oescribed above with respect to Figures S and SA, together witb certain range-taking features. Thus, the cone 34E has an apera re 90 (Figures 7A and 7B) at its front, gel-facing conical suriace, as can be seen particularly in Figure 7A showing a section tbrough the cone. Gel 46 (not shown) enters through the aperture 90 and may exert a force on the outer surface of the stress cone, acting as a diaphragm 92 to extend into a cavity formed in the housing (not shown) in a manner analogous to that described with reference to Figures 5 and SA, but with the cavity fonned in tha[ part of the housing enclosing the body of the cone 34E. Alternatively, or additionally, the rear surface 94 of the aperture 90 can act as a diaphragm in a marmer analogous to tbat described with reference to Figures 4 and 4A.
The stress cone 34E bas in addition. range -taking fearures that allow it to be used with cables of various diameters, within a given range. Thus, the stress cone 34E has three apertures 96, 98, 100 therein, vented to its rear surface (Figures 7 and 7A), definmg two channels 102, lW fh".d-.,... that extend u~ clJ into the cone anfi 1~, _ " Iy partly thereinto from the rear surface. The operation of the range-taking ability of the case 34E, and its co-operation with the outer housing, are described hereafter with reference to Figures 9 and 10.
The rlllilO,I;.,.. ~ :- discussed above allow for extenslon of the volurne of the gel 46 m the joint as it increases its ~ C, either due to increase m the temperature of the enclosed cable in operation, andlor due to increasing ambient tclllf~,la~c around the outer housing 40. However, since in the usual condition of the joint, that is to say, for the greater part of its lifetime, the gel 46 will be hot amd thus expanded, it is also envisaged that . may instead be made for contr~tion under certam conditions, such as for example when the power through the cables is interrupted. The gel- ' l ' , in so far as it relies upon movement of a resilient member, may then be SVBSTIIUTE SHEET lRULE 261 ~ wo96/02079 2 1 94~3~ 623 arranged so as to be in its relaxed condition whilst the gel is extended, and be arranged to stretch upon cooling and reduction in volume of the gel, thereby to maintain pressure on the gel. Figure 8 shows an f~ ; 1 '1 of such an ,.~ , in which the stress-relief cone 34F has an aperture 110 locally at its outer l,il~.UlllE~ adjacent the housing wall 60F.
The housing 60F has a cut-out portion 112 adiacent the aperture 110 but is separated therefrom by a flexible membrane 114 secured thereacross . The cut-out 112 is vented to the rear of the stress cone 34F. The membrane 114 and its securement to the housing 60F is arranged such that under normal operating conditions of the joint, the expanded gel 46 fills tbe aperture llO and the diaphragm 114 ;s in its relaxed state. Upon cooling, amd thus contraction of the gel 46, the diaphragm 114 is urged by excess air pressure from the venting chamber (not shown) to stretch, to extend into the aperture 110, and to adopt the position shown m dotted outline, and thus to maintain pressure on the gel 46.
It will be appreciated that the concept described with reference to Figure 8 could be applied to'o~her ,.. l, ~ for example that described with reference to Figures 5 and 5A.
Figures 9 and l O show ~ ,o~ of a range-taking dl l~.~ .,... for providing aseal on to one of number elongate substrates of various diameters, ~Y~uriifi~d by being applied to a stress-relief cone for use, for example, in the joint of Figure l. A housing 160 is of a relatively rigid, conductive polymeric, POIY"I~IJY~ " material, and is in the form of two generally-cylmdrical half-shells (only one of which is shown). At each end. the housing 160 is provided with two ~ub~4llLi~lly parallel and inwardly-directed planar projections or fins 162 for engaging with respective stress relief cones 164, each of which is also formed as two half cones. The stress cones 164 are formed from a relatively flexible conductive rubber material and have slots 166 therein for receiving respective ones of the projections 162. As can be seen from Figure lO, when hwo such 1., . ~, l~, l.. ~ as described with reference to Figure 9 are brought together around a cable 168, the softer material of the, now fully-formed stress cone 164 will tend to stretch over the outer diameter of the cable 168 and will tend to separate along the join surface 170 of the two halves of the joint enclosure. However, the rigidihy of the projecting fins 162 extending mto the stress cone 164 on each side of the cable 168 restrain movement of the cone 164 away from the cable 168 at the mterface 170.
In the exarmple shown in Figures 9 and 10, the stress cone 164 is provided with apertures 172 in its flexible material, opening towards the rear of the conical surface, thaL is to say at its surface away from the crimp region of the joint, on each side of the slots 166, SUBSTlTUTE S5~EET (RULE 26) Wo 96/0207g PCT/Gh(l~fOI623 ~
2t, ~42~J
wbich are re-inforced in the assembled cu~lriL~ " by the fins 162. The apertures 172 enhance the ability of the inner surface of the stress cone 164 to stretch over a cable 168 so as to _ ' cables of larger si~e whilst ~ a good seal ~ l C~ uullJ at the interface 170. The central aperture 172 in particular defines an inner, semi cylindrical membrane that can be stretched aromld the cable 168, with the rigid reinforcing projections 162 urging the two halves of the cone 164 into conformity with the enclosed cable 168 at the interface 170.
It will be appreciated that tbe reinforcing h~t~ "L' ~ 11 r~ 1 of Figures 9and 10 allows conformity with elongate substrates other tban by means of using a stress-relief cone. The concept can be used for example to provide a seal around a shaft, or as a bushing where a cable, which may be of one of a number of diameters, passes through a bulkhead.
Referring to Figures 11 and 12, a half cone 800, I~l,.r;lclulc-l from a conductive rubber rnaterial, is a ~ iril ~liu" of the half cone 164 of Figures 9 and 10. It will be appreciated that. Iike tbe half cone 164, the half cone 800 has a closed front end, and rhat one half cone will be located at each end of each half shell tiut forms the closure around the cable joint (only part of one half-shell being shown in Figures 11 and 12). At the rear (as shown) of the half cone 800, a large aperture 802 extends to the closed front surface of the cone, and is radially closed by the balf shell 8W. The aperture 802 is divided into three portions by a psir of frns 806 that extend generally radially from the inner surface of the half-shell 804, in a manner srmiiar to the way in which the fins 162 e~ctend from the housing half shell 160 as shown in the ~ ~ul; .. -: of Figcre 9. The fins 806 are disposed so as, in operation, to lie ore on each side of the cable within the joint. A relatively thin wall portion 808 at the inner side of the half cone 800 is arched so as, in operation, to conform around an encloseci cable and so as to receive and guide the free, inner ends of the fins 806. As shown in Figure 11, the fins are positioned relatively close to the ~ hulin~l axis of the joint, and the length of the arched portion of the inner wail 808 of the half cone 800 is miritinised. In this position of tbe fins 806, the haif cone 800 will conform to a minunum diameter size cable ~not shown). As can be seen from Figure 12, the frns 806 have a flexibility that ailows them to splay outwards and to allow a greater length of the arched wall portion 808 to extend Ih.,lel,.,~.. In this position, the half cone 800 will conforrn to a maxrmum diameter size cable. It is to be noted that in this ell~ unl~e that of FigLire 9 and 10, the irmer half cone surface 808 is not sh etched. The presence of the fins 806, however, still ensures ~ul, .~lliolly complete conformity of the completed cone around a range of sizes of cable, without air pockets being present at the interface of the two half cones adjacent the SUSSTITUTE SHEET ~RULE 26) wo 96,020,9 ~ 1 9 4 ~ 3 ~ PCTiGB9S/01623 - t7-cable surface. It will be appreciated that the flexibility of the fins 806 is such that they are able to splay outwards around a larger diameter cable but that they are reiatively rigid with respect to the softer elastomeric material of the half cones 800.
An alternative, or additional, way of providing for expansion of the gel 46 u the joint of Figure 1, is shown with reference to Figure 13A ard also with reference to Figures 13B and 13C, each of which shows a Faraday Cage modified from that illustraoed at 28, 30 in Figure 1. Referring to Figure 13A. the two half-shells 28A, 30A are formed from flexible conductive polyrneric rnaterial, and contain three apertures 120, therein. As the gel 46 expands, the mcreased pressure is exerted on the half shells 28.4., 30A, which deform by c--~ ll of the apertures 120. Cooling of the gel leads to expansion of the volume of the apertures 120 and thus to the ."~i".~ -, e of pressure on the gel 46.
A ~ ;r~ . of the ~ L' ~ ~1 of Figure 13A is shown in Figures 13EI and 13C, in which each end of tbe half-shells 28B and 30B is sealed on to the cable dielectrics 18, 20 so as to defule two apertures 122 located withtn the Faraday Cage 28B, 3ûB around the criunped conductors. As shown in Figure i3C, the apertures 122 r~ an mcrease of gei pressure by inward flexing of the half-shells 28B, 30B upon expansion of the gel 46.
Figures 14 and 15 disclose two ., I.o.l;., ~1' of the joint concept of Figure I in which change of volume of the sealant material 46 is: ~~ ~ ' ' by a ,"-- I r~ ., of the .~1, of the outer housing 40.
In the ~ ,I,o.l;.... l of Figure 14, the generally rigid outer housmg 40C is provided as part of its surface with flexible wail 130 that is subject to the pressure of the gel 46 ~not shown) contamed therein. To complete the rigidity of the housing 40C overall which may, in operation, be buried in the ground, a rigid cover 132 is arranged to fit over the flexible wali 130 to defme a cavity therewith. A resilient block 134 of rubber is located within the cavity. Thus, on expansion of the gel 46, the flexible wall 130 will transmit the pressure into C~ LIL,~IeL~ of the bloclc 134 against the restraint of the rigid housing 40C, and on rC~nrt~r~ n the wall 130 will maintain pressure on the gel so as to prevent formafion of voids around the joint.
The ,'~ of Figure lS is arranged to achieve the same effect as that of Figure 14, but to this end each half of the housing 40D is made of a rubber material and has a L,il,~UllllrL,lCllLidi portion 140 of thinner section adjacent the stress cone 142 so as SUBSTITUTE SHL~T ~RULE 26) wo 96102079 pcrlGss5lol623 2 "~
~s idlly to expand, ' any increase in gel volume, and to exert a restoring force thereon.
Referring to Figures 16, 17 and 18 an elongate semi-cylindrical integral rubber moulding 1000 has a relativeiy tifin wall ill~l '' section 1002 ~Figure 17) and a pair of relatively thick wail end sections 1004 that have a half-stress cone 1006 formed on the inside thereof (Figure 18). The moulding 1000 is arranged to be fitted into a rigid plastic outer case 1008 that is radially spaced therefrom aiong at least part of the i ' section 1002. D~ --- a or expansion of the gel filling material within the moulding 1000 results in flexing of the i ,~ section 1002 into the expansion chamber provided by the outer case. preferably fonned trom a pair of half-shells, of the completed joina The rigid intemal support members 150,160 discussed hereinafter with respect to Figures 21, 22 and 22.4, may be integrated into the rubber mouldmg 1000 and located by snap-fitting into the outer plastic case.
Refenring to Figures 19 and 20, two cables 1140 and 1142 are sho vn schemically ~ jointed at 1144. A ~, lA jJ.:l~lUII i elastomeric insulating body 1146 has fingers 1148 at each end thereof than can be tapered down to confonm with the reduced diameter of the cables 1140, 1142 on each side of the joint region 1144. One cylindrical closure member 1150 is initially rolled on to each of the cables 1140, 1142. The closure members 1150 are formed from conductive rubber.
Figure 20 shows the joint partially completed. The insulating body 1146. which rnay comprise a mating pair of half-shells rather than being of the wraparound Cl/~ ,ri,! " Al i~ ~11 as shown. encloses insulating gel material 1152 and may also contain solid insuiation enclosing the gel sealant. The body 1146 is closed around the joint 1144 amd the fingers 1148 brought down on the cables 1140, 1142. One conductive closure member 1150 is shown as having been uncurled from its parked position on the cable 1140, so as to e~tend to just more than halfway across the body 1146. The other, still-parked closure member 1150 on cable 1142 wiLI then be uncurled so as to overlap the first closure member. In this way, the insulating body 1146 including both its fingered end-sections 1148, and the entire cable joint region is enclosed within the two conductive outer members 1150.
Figures 21, ~2 and 22A disclose ell-L " of cable joint in which a conductive component such as a Faraday Cage, can be supported within the joint whetl it is otherwise SUBSTITUTE SHEET (RULE 2B) ~ WO 96/02079 2 1 9 ~ ~ 3 ~ PCT/GB95/01623 enclosed by non-rigid material, and in particular can be positively located with respect to an outer conductive housimg.
In Figure 21, the arcuate Faraday Cage 28c is made of conductive polymeric material, is disposed in silicone gel sealant 46 as h..c,...v.,fulc, described, is radially spaced (by means not shown) from the enclosed crimped conductors (not shown), and is located axially between stress cones 34G and 36G. These '"~ ~ ~'~ are enclosed within the outer housing 40 of ' ~ly - filled pol,yl.lu~lul..,. Under certain conditions, and especially when the ~ lu~ .C of the gel 46 is increased~ there is a likelihood that the conductive cage 28c could move laterally within the gel 46 towards d1e housing 40, which is at earth potential, and thus forrn a short circuit from the high voltage of the cable conductors. In this C;lllbUllilll_l~i, movement of the cage 28C is pre~ented by employing an insulating polymeric support cradle or spacer 1~0. The cradle 150 is arcuate and mounted in the anmular gap between the cage 28C and the housing 40, and, like those r~ ,u. ."~, is formed as two half-shells. Fach half of the spacer 1~0 is provided with a series of projections on each of its curved surfaces so as to distance it from both the cage 28C and the housing 40, thereby to allow gel 46 ~uL~ completely to fill the space ~ lUUIId.
The spacer 150 is arranged to provide good physical i..t~,.c v v witn both the cage 28C and the housing 40, for example by means of ;m~ .g projections and apertures andlor a snap-fitting m~rh--:-m thereby securely to maintain the conductive cage 28c in position both radhlly and l. ~ ly within the joint.
Figures 22 and 22A show another variation of support member for use with a Faraday Cage. Referring to these Figures. the polymeric insulating support member 160 is of partial semi- cylindrical ~ . being flanged at each end so as to provide for an annular chamel 162 between the support 16Q and the outer housing 60 when used inoperation to support the Faraday Cage 28. As shown in Figure 22A, which is a section through one of the half-shell ~ of the joint, the Faraday Cage 28 and housing 60 are fully semi-cylindrical so that when brought together v.~ith the ~.l..r~l... l:- ;~ half-shell around the crrmped conductors (not shown), the cylindrical surfaces thereof are completed.
The two half shells of the support member (only the one 160, being shown) however ex[end for less than 180 degrees, with the region tL.el,~.-.".,." as well as the channel 162, being filled by the gel 46, to provide a gellgel radial interface between the Faraday Cage 28 and the housmg 60 on closure of the two half shells around the crimp region. The support member 16Q may be mr~rh~nir~lly inrrrlr~rkrrl as described with reference to thermhorlimrn- of Figure 21 for example, with both the Faraday Cage 28 and the housing 40 of its respective half shell so as securely to locate the Faraday Cage 28 within the joint.
SUESTITUTE SHEET (RULE 26) WO 9~1U20n rC'iL'~G119~ilO1623 ~1 ~At.~
The support spacers 150, 160 may but need not extend Ir~n~ituriin~lly CO .~lugullJu.~Iy with the associated Faraday Cage.
In a further l~u~l;ri~ ", it is envisaged that the support member may be mouldedintegrally with the Faraday Cage andlor the housing. In such a cv1~LIuuLiOu, the rnoulding operation itself may exclude air from the moulded surface of the support member, thus avoiding the need to allow the gel 46 to have access to any interface between the support member and the Faraday Cage and/or housing.
Figures 23 and 23A show two different ",..ri~ ",~i,. . by which the lrmgihlrli edges of the two half shells of the housing of a cable joint can be imerlocked. In each case~
one edge 180,180A is provided with a groove 182,182A extending therealong, being of trapezoidal section in Figure 23 aDd of key-hole section in Figure 23A. The grooves 182,1S2A are filled with gel, al~c,l~6.,u_~ly the same as that providing the bulk insulation of the joint. The opposing edges 184,184A of the housing are provided with uullc~l~u..1ul~ly-shaped projections 186,186A. Upon closure of the two half shells of the housing around the electrical connection, the projection 186,186A engages the associated groove 182,182A, and the gel forms a seal Lh~lcl~
Referring to Figure 23B, a cross-section is shown of a jointed cable 5r~hr~m~rir ~lly at 200 partially embedded in gel 202 that is contained in each part of a pair of half-shells 204, 206. The half-shells 204, 206 are substantially semi-cylindrical and are hirged together at 208 along one pair of longih-ri;n~l edges. The hinged cylindrical housing forrned by the two half-shells is closed around the jointed cables and Figure 23B tepresents the situation just prior lo closure of the housing. The l ~' " ' edges of the half-shells 204, 206 opposite the hirge 208 are provided with a co-operating tongue 210 and groove 212 ~
along the ma3Or part of the length of the housing w hich contains the gel 202 that is to be urged into conformity around the enclosed jointed cables. The tongue 210 ls of such a length, in the .i.~ ~ -5 .c,,~ direction, that on closure of the two half-shell 204, 206, il engages the groove 212 before pressure on the gel 202 is sufficient to exude it sideways out of the housing. In this way, all the gel 202 is cornpletely contained within the closed housiog ~,h~u~uf~lcuficlly, thus avoiding any possible shearing of the gel that could .,_b~ ..uLly lead to the creation of voids within the housing.
SUBSTITUTE SHEET (RULE 26 WO 96102079 ~ 5 0 PCT/GB95/01623 Positive locicing together of the two half-shells 204, 206, is achieved by a plurality of discrete projections 214 along the outer surface of the tongue 210 which snap into co-operating apertures 216 in the outer wall of the groove 212.
Sealing of the housing against ingress of moisture, air, dust or other ~ ' aroumd its periphery at the mterface of the two half-shells 204, 206 is enhanced by the provision of a ridge 218 around the entire periphery of the half-shell 206 that tightly engages with a mating peripheral depression 220 in the half-shell 204.
Finally, the two half-shelis may be secured together by toggle clips or other suitable fastening means applied externally of the closed housmg.
Referring to Figure 24, a joint between two screened cables 1160, 1162 is enclosed within a two-part housing 1164. A slot 1166 is cut axiai iy into the housing 1164 at each end thereofml.,.,~ ;"Alalignment,andtilescreenwiresll68,11700fthecablesll60,1162 .-,.,t,..~i~.ly are brought out through the slots 1166 and crimped together at 1172 over the outer housimg surface. The connecting together of the screen wires 1168, 1170 and their : ~ _ witbin the slots 1166 in this mannel-, prevents the housing 1164 from moving either rotationaily or l-~ngjh~ ly with respect to the jointed cables.
Referrmg to Figure 25, the housing 1180 is formed from two semi-cylindricai half-shells that are hinged together at 1182 aiong its central portion, and that are sealed by a tongue and groove Al I"'~L~ 1 around their rnating peripheries. Beyond a tapered portion towards each end of the housing 1180, a cylindrical portion 1186 is forrned between a pair of ribs 1188thatextendaroundthel,h~ r c~eofthehousmg. Thehousing 1180is secured on to the enclosed jointed cables by means of tape, a tie-wrap, a roll-sprmg or the like 1190 that is wrapped around the cylindrical housing portions 1186. To enhance the sealing, and to assist the retention, of tne housing on the cables. mastic or other sealant materiai may be located between the housing portions 1186 and the underlying cable jackets.
The seaiant rnaterial may be appiied to the cables as a wrappmg, or may be retained by the housing 1180.
SUEST~TUTE SHEET (R~LE 26
Claims (19)
1. An enclosure arranged to enclose a connection between a screened electric power cable and another piece of electrical equipment, the enclosure comprising a housing, at least one electrical stress cone contained within the housing, and a quantity of compressible sealant material that is contained by the housing and that substantially fills the housing when enclosing the interconnection, wherein the or each stress cone comprises resilient aperture means that is arranged to change its volume in response to a change of volume, or displacement, of the sealant material thereby, in operation, to maintain substantially complete filling of the housing around the interconnection without the formation of voids therein.
2. An enclosure arranged to enclose a connection between a screened electric power cable and another piece of electrical equipment, the enclosure comprising a housing, at least one electrical stress cone contained within the housing, and a quantity of oil-extended polymeric sealant material that is contained by the housing and that substantially fills the housing when enclosing the interconnection, wherein the or each stress cone comprises resilient aperture means that is arranged to change its volume in response to a change of volume or displacement of the sealant materialthereby, in operation, to maintain substantially complete filling of the housingaround the interconnection without the formation of voids therein.
3. An enclosure according to claim 1 or claim 2, wherein the resilient aperture means is arranged (a) on expansion or displacement of the sealant material to becompressed or to be reduced in volume so as to accommodated the increased sealant volume, and (b) on contraction of the sealant material to exert pressure thereon so as to prevent the formation of voids therein.
4. An enclosure in accordance with any one of the preceding claims, wherein, in operation, the resilient aperture means is in a relaxed condition when the sealant material is in an expanded or displaced state, and is stretched when the sealantmaterial is in a contracted state.
5. An enclosure according to any preceding claim, wherein the resilient aperture means of the stress cone is provided by a void or gaseous entrapment contained completely within a resilient portion of the stress cone.
6. An enclosure according to any one of claims l to 4, wherein the resilient aperture means of the stress cone is provided by a void or gaseous entrapment located between a resilient portion of the stress cone and a non-resilient portion of the housing.
7. An enclosure according to any preceding claim, wherein the resilient aperture means of the stress cone comprises an aperture containing a resilient arrangement that is subject to the pressure of the sealant material.
8. An enclosure according to claim 7, wherein the resilient comprises a spring and a plunger retained within the aperture. the plunger closing the aperture to entry of the sealant material and in contact therewith.
9. An enclosure according to claim I or claim 2, wherein the resilient aperture means comprises an aperture that contains or can receive some of the sealant material, the aperture having a resilient wall for urging the sealant material into the connection region.
10. An enclosure according to any one of the preceding claims, wherein the sealant material comprises gel.
11. An enclosure according to any one of the preceding claims, wherein the electrical equipment comprises a further screened electric power cable and the housing contains a stress cone associated with each cable.
12. An enclosure according to any one of the preceding claims comprising an electrically - conductive member that is arranged, in operation, to be disposed around the connection of the cable conductor to the equipment as to make a region there around substantially free of electric field.
13. An enclosure according to claim 12, wherein the electrically-conductive member is resilient, thereby, to exert a pressure on the sealant material.
14. An enclosure according to any one of the preceding claims, wherein at least a portion of a wall of the housing subject to the pressure of the sealant material is resilient so as, in operation, to accommodate expansion of the sealant material.
15. An enclosure according to claim 12, comprising location means arranged to support the electrically - conductive member and to maintain its position within the sealant material.
16. An enclosure according to claim 15, wherein the housing has an electrically conductive outer surface for sealingly enclosing the sealantmaterial, wherein the location means comprises electrically insulating material and is arranged to secure the electrically conductive member to the housing.
17. An enclosure according to any one of the preceding claims, wherein the stress cone comprises (a) a relatively rigid component and (b) relatively resilient component, wherein the rigid component, in operation. is arranged to urge the resilient component into substantially complete conformity around the cable.
18. An enclosure according to any one of the preceding claims, wherein the housing is in two parts, each part of which contains a part of the stress cone and part of the sealant material, such that, in operation, on closure of the two housing parts circumferentially around the interconnection, the two parts of the stress cone mate around the cable and the sealant material forms an interfacial seal between the two parts of the housing and with the interconnection.
19. An electrical interconnection between a screened electric power cable and electrical equipment, wherein the cable is cut back such that the conductor, primary dielectric and screen thereof are exposed, wherein an enclosure in accordance with any one of the preceding claims is disposed around the interconnection with said at least one stress cone being located at the end of the cable screen.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9414039.9 | 1994-07-11 | ||
| GB9414039A GB9414039D0 (en) | 1994-07-11 | 1994-07-11 | Electrical interconnection |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2194230A1 true CA2194230A1 (en) | 1996-01-25 |
Family
ID=10758206
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002194230A Abandoned CA2194230A1 (en) | 1994-07-11 | 1995-07-10 | Electrical interconnections |
Country Status (14)
| Country | Link |
|---|---|
| US (1) | US5900585A (en) |
| EP (1) | EP0770278B1 (en) |
| JP (1) | JPH10502797A (en) |
| KR (1) | KR970705211A (en) |
| CN (1) | CN1157064A (en) |
| AT (1) | ATE177262T1 (en) |
| AU (1) | AU2893995A (en) |
| CA (1) | CA2194230A1 (en) |
| DE (1) | DE69508086T2 (en) |
| DK (1) | DK0770278T3 (en) |
| ES (1) | ES2128746T3 (en) |
| GB (1) | GB9414039D0 (en) |
| GR (1) | GR3029547T3 (en) |
| WO (1) | WO1996002079A1 (en) |
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| US4863535A (en) * | 1987-12-09 | 1989-09-05 | Minnesota Mining And Manufacturing Company | Electrical environmental sealant and method |
| GB8729454D0 (en) * | 1987-12-17 | 1988-02-03 | Ass Elect Ind | Power cable jointing method |
| WO1990010035A1 (en) * | 1989-03-01 | 1990-09-07 | Raychem Corporation | Method of curing organopolysiloxane compositions and compositions and articles therefrom |
| JP3056888B2 (en) * | 1992-07-30 | 2000-06-26 | 株式会社フジクラ | How to connect the power cable |
| GB2269712B (en) * | 1992-08-12 | 1996-05-01 | Ass Elect Ind Ltd | Electric power cable jointing |
| IL111241A (en) * | 1993-10-18 | 1998-02-22 | Raychem Corp | Closure for high voltage cable connections |
| GB9414038D0 (en) * | 1994-07-11 | 1994-08-31 | Raychem Ltd | Electrical interconnection |
-
1994
- 1994-07-11 GB GB9414039A patent/GB9414039D0/en active Pending
-
1995
- 1995-07-10 US US08/765,992 patent/US5900585A/en not_active Expired - Fee Related
- 1995-07-10 DE DE69508086T patent/DE69508086T2/en not_active Expired - Fee Related
- 1995-07-10 DK DK95924441T patent/DK0770278T3/en active
- 1995-07-10 JP JP8504195A patent/JPH10502797A/en active Pending
- 1995-07-10 CN CN95194864A patent/CN1157064A/en active Pending
- 1995-07-10 AU AU28939/95A patent/AU2893995A/en not_active Abandoned
- 1995-07-10 CA CA002194230A patent/CA2194230A1/en not_active Abandoned
- 1995-07-10 ES ES95924441T patent/ES2128746T3/en not_active Expired - Lifetime
- 1995-07-10 WO PCT/GB1995/001623 patent/WO1996002079A1/en not_active Application Discontinuation
- 1995-07-10 EP EP95924441A patent/EP0770278B1/en not_active Expired - Lifetime
- 1995-07-10 AT AT95924441T patent/ATE177262T1/en not_active IP Right Cessation
-
1997
- 1997-01-10 KR KR1019970700134A patent/KR970705211A/en not_active Application Discontinuation
-
1999
- 1999-03-04 GR GR990400307T patent/GR3029547T3/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10502797A (en) | 1998-03-10 |
| DE69508086D1 (en) | 1999-04-08 |
| US5900585A (en) | 1999-05-04 |
| ES2128746T3 (en) | 1999-05-16 |
| GB9414039D0 (en) | 1994-09-28 |
| ATE177262T1 (en) | 1999-03-15 |
| DK0770278T3 (en) | 1999-09-27 |
| EP0770278B1 (en) | 1999-03-03 |
| KR970705211A (en) | 1997-09-06 |
| WO1996002079A1 (en) | 1996-01-25 |
| AU2893995A (en) | 1996-02-09 |
| EP0770278A1 (en) | 1997-05-02 |
| DE69508086T2 (en) | 1999-09-30 |
| GR3029547T3 (en) | 1999-06-30 |
| CN1157064A (en) | 1997-08-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |