CA1063685A - Insulated electric wire and method of making this wire - Google Patents
Insulated electric wire and method of making this wireInfo
- Publication number
- CA1063685A CA1063685A CA266,318A CA266318A CA1063685A CA 1063685 A CA1063685 A CA 1063685A CA 266318 A CA266318 A CA 266318A CA 1063685 A CA1063685 A CA 1063685A
- Authority
- CA
- Canada
- Prior art keywords
- fibres
- conductors
- sheath
- sheaths
- conductor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
- H01B13/06—Insulating conductors or cables
- H01B13/12—Insulating conductors or cables by applying loose fibres
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B11/00—Communication cables or conductors
- H01B11/002—Pair constructions
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B11/00—Communication cables or conductors
- H01B11/02—Cables with twisted pairs or quads
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B7/00—Insulated conductors or cables characterised by their form
- H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
- H01B7/18—Protection against damage caused by wear, mechanical force or pressure; Sheaths; Armouring
- H01B7/189—Radial force absorbing layers providing a cushioning effect
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B7/00—Insulated conductors or cables characterised by their form
- H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
- H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
- H01B7/282—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
- H01B7/285—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable
- H01B7/288—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable using hygroscopic material or material swelling in the presence of liquid
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Communication Cables (AREA)
- Materials For Medical Uses (AREA)
- Insulated Conductors (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Telephone cables are constructed from helically twisted pairs of insulated conductors, the insulation of each conductor having embedded therein projecting fibres distributed throughout the length and circumference of the conductor. The fibres of adjacent conductors intermesh and maintain constant the spacing between conductors and the pitch of the helix.
Telephone cables are constructed from helically twisted pairs of insulated conductors, the insulation of each conductor having embedded therein projecting fibres distributed throughout the length and circumference of the conductor. The fibres of adjacent conductors intermesh and maintain constant the spacing between conductors and the pitch of the helix.
Description
~4~36~5 This invention relates to telephone cable elements~
Telephone cables are always formed from elements consisting of insu]ated wires ~rouped in twos or fours, known respectively as pairs and quads. The pairs may consist of either two coaxial conductors or helically twisted wires. In this latter case they are known as symmetrical pairs. The quads are either formed from four twisted wires (star quad), or from twisted wire pairs which are themselves twisted, and known as D~ (Dieselhorst-Martin) quads or symmetrical pair quads. These pairs or quads form the elementary circuits of a cable. The present invention relates in particular to star quads, DM quads and symmetrical pairs.
The proximity of the conductors grouped in a cable means that the telephone circuits are not totally independent of each ' other. Interactions are produced, and parasite signals may be detected in a particular circuit, generated by the passage of signals over other circuits. This phenomenon is known as cross-talk and is manifested in practice by the awareness of a telephone eonversation transmitted over a neighbouring circuit.
Corss-talk i5 influenced by the electrical resistance of ` the elementary circuits, by the capaeitance of these circuits, and in partieular by their eapaeitance dissymmetry. These same parameters also eontribute to line attenuation, whieh results in a :::
deerease in the sound level of the transmitted eonversation and should of eourse be as low as possible.
; The eleetrieal resistance of the circuit is defined by parameters which can be fairly easily controlled, namely the resistivity of the metal used for the conductor, the constancy of this resistivity along the line, and the conductor dimensions.
The capacitance and capacitance dissymmetries, the influence of which is preponderant in eross-talk questions, depend on the dieleetrie constant of the insulant utilised, which . . .
~ , . .. .
- , ...... - ~ : ' , . : : '' ' : . .
, . . , : :
6~3~
is a measurable and reproducible parameter, but they also depend on other parameters much more difficult to control and which are related to the geometry of the quad. This geometry results from the helical assembly of the quad wires, and it is obvious that it is very difficult to control such geometry with rigorous precision, and in particular to ensure that no displacement of the wires in the quad occurs during the further cable manufacturing operations.
For a long time, cables were insulated with spirally wound paper strip, but this insulating material, which is relatively fragile, of low productivity and leads to complications in splic ing, has now been replaced by plastics insulation applied by extruding machines.
This plastics insulation has the disadvantage of a high-er dielectric constant, which requires the thickness of the insulation to be increased to obtain the same line attenuation.
In addition to these d~fects deriving from the nature of : ;
; the insulation, two other defects may be indicated which derive indirectly from the use of plastics insulation. First, it is difficult to ensure accurate centering of the conductor in the sheath produced by an extrusion machine. Eccentricity of the .:~ I' .
i conductor has repercussions over the entire length of the wire, and creates capacitance dissymmetries. Furthermore, even when this defect is practically non-existant, the stability of the geometry of quads formed from wires insulated by plastics sheaths is poor because of the low coefficient of friction between the sheaths, so that the wires may become displaced and create capacitance dis-,. . .
symmetries, in particular during the cable manufacturing operations which follow the manufacture of the quads themselves.
Finally, and in contrast to paper insulation, plastics insulation offers no protection to the cable against water infil-tration if the cable envelope becomes defective.
- Among the numerous solutions which have been advocated, ~' '.' ~ -2-. .. .
.
it has been proposed in sritish patent No 1,40~,068 to fix cellulose fibres around a plastics sheath to form a hydrophilic region about the sheath, capable of swelling in the presence o~
water, to become a seal which prevents water progressing along the cable. According to this method, the purpose of the plastics - sheath is to insulate the electrical conductor which it envelops, while the purpose of the cellulose fibres is to prevent water in-filtrating along the cable by the hydrophilic proper-ty of the ; cellulose.
The object of the present invention is to improve the capacitance symmetry of telephone circuits, using wires the insulation sheath of which is surrounded by a plurality of fibres.
~ To this end, the present invention provides a telephone ;~ cable element formed from at least one pair of helically twisted electrical conductorscomprising, in combination: a respective insulating sheath enveloping each of said conductors, and a plurality of fibres embedded in the wall of each of said sheaths so that they project all round said sheaths, the lengths of these fibres and their density being chosen so as to maintain between said conductors `- 20 a determined spacing which is a function of the desired capacitance between the conductors, the average length of said fibres and the density at which they are embedded in said sheaths being kept con-stant so that said spacing remains uniform over the entire length of the cable element, the projecting portions of said fibres form-ing members of which the sheath of one conductor is fastened to the sheath of the other conductor by the mutual interpenetration of the fibres of the adjacent sheaths, such that the pitch of the helix is :
kept constant and uniform over the entire length of thecable element.
~ 30 Telephone cable elements constructed in accordance with I the invention have shown that, regardless of the nature of the fibres utilised, the presence of these fibres of given average , ~3~
length embedded in the sheath at a constant density enables a - -spacing to be maintained between the conductors which is a function of the desired capacitance, and to give said capacitance a symmetry which is absolutely surprising, and very difficult to obtain wi-th extruded insulation. Moreover, when bundles and cables are manufactured using pairs of quads according to the invention, it is found that these elements have not undergone any deformation, because of the interpenetration of the fibres in the adjacent regions of the conductors, and in contrast to that which happens with all other known forms of insulation, which allow the twisted conductors to become displaced relative to each other during the further cable manufacturing operations.
The importance of these advantages and of other accompanying advantages will be more evident from the description given hereinafter.
The accompanying drawing represents a diagrammatic illustration by way of example of cable elements according to the presentinvent~ion; In the drawing:
Figure 1 is a perspective view of a pair;
Figure 2 is a cross-section through a quad of ~ ~ -symmetrical pairs; ~
. .
Figure 3 is a cross-section of a star quad;
Figure 4 is a diagram which is useful in defining the ; parameters k which are a measure of capacitance dissymmetries; and :. : :
Figure 5 is a diagram showing the various factors which can modify the value of the aforementioned parameters.
, Figure 1 shows a pair 25 formed from two wires 24 twisted into a helix of constant pitch. Each of the wires comprises a i conductor 2 enveloped by a plastics sheath 19 in which a plurality { 30 of fibres 21 are anchored. The pair 25 is designed to constitute a telephone cable element forming a telephone circuit or line. As can be seen in Figure 1, the fibres 21 which cover the respective ... ..
. ~ .
insulating sheaths 19 mutually interpenetrate in the adjacent parts of the twisted wires. Consequently, these fibres act as distant pieces between the insulating sheaths formed about the conductors 2, the diameter of which in this example is 0.6 mm, the sheaths being preferably of expanded polyethylene about 0.2 mm thick, the avarage length of the fibres then being about 1 mm and their diameter 25 denier. The polyethylene layer ensures good mechanical strength and sufficient electrical strength. The fibres, which are preferably cellulose fibres, have a good insulation resistance when dry, and a low dielectric constant which is less than that of the plastics material alone.
If the surrounding cable envelope (not shown in Figure 1) is ruptured and water penetrates into its interior, the cellulose fibres have a duel function of impeding, by their swell-ing the progression of the water along the cable and, through a lowering of their electric resistance, sharply increasing the leakage current and thus signalling the existance of a defect.
.'~
~ The blocking of the flow by the swollen fibres is highly effective .
and limits the damage to a short length of-cable. The location of the leak can be readily pinpointed by measurements of the current flow and the voltage drop along the line.
Even if the effecti~e length of the projecting fibres varies somewhat about its mean value, the spacing of the conductor cores remains substantially unchanged during handling so that no `~ significant variations in the shunt capacitance between the -conductors occur. Stabilization of this shunt capacitance at a predeterminedmagnitude is essential for the suppression of cross-talk between circuits of a ~uad including the conductor pair of Figure 1, as more fully discussed hereinafter with reference to Figure 4.
In a specific instance, fibres of the dimensions given above have a density of about 400 g/km.
.', .
.
.~ . j , '' .
;, . .
The fact that the sheath is not extruded but is produced by the melting of polyethylene powder, as described in the abovementioned British patent, also contributes to the mainten-ance of the desired symmetry inasmuch as any irregularities in the coating process tend to be distributed at random around the conductor axis; on the other hand, any irregularity of an extrusion nozzle leads to a distinct eccentricity of the sheath. The inter-leaved fibres also resist any relative axial shifting of the conductors which in the absence of the fibres could occur during -handling, thereby unbalancing the circuit.
; Figure 2 shows two balanced pairs 25 of the type illustrated in Figure 1 within a common, flexi.ble envelope ` illustrated diagrammatically at 26.
Figure 3 shows a star quad 25' disposed within an envelope 26; the array 25' consists of four insulated conductors - 24 twisted about a common axis, the conductor axes lying at the : corners of a square, in any transverse plane. In this instance, ~ .
- the fibres 21 interpenetrate not only in the spaces between adjoin- .
.i ing conductors but also in a central channel 27 which would be .; . . ~., . :
. 20 completely empty in a quad composed of conventionally sheathed .
conductors including those with paper wrappings. While such .~
, wrappings could form a barrier between adjoining conductors, they .
would.not:swell sufficiently to block the flow of water in the vicinity of the cable axis. Envelope 26 may, of course, embrace a .
multiplicity of arravs 25 and/or 25'. ..
We shall now refer to Figure ~ for a discussion of the ~
part played by the various shunt capacitances in a quad forming i three signalling circuits as noted above. In Figure 4 the four ~.. -conductors are designated a,b,c and d; the interconductor e Cac, Cbc, Cad and Cbd; and the shunt capacitances with reference to ground are Cao, Cbo, CCO do circuit consists of wires a (outgoing) and b (incoming), the .' ":
., ~ ,.
.. . . . ; . : .. ;. : .
6~
second circuit consists of wires c (outgoing) and d (incoming), and the third or phantom circuit consists of wires a, _ (outgoing) and c, d (incoming). We can then define the cross-talk among those circuits in terms of three parameters, namely a factor k relating to the first and second circuits, a factor k2 relating -to the first and third circuits and a factor k3 relating to the second and third circuits. These parameters are glven by the following equations;
klCaC + Cbd Cbc Cad ':
10 k2bc Cbd Cac Cad 2 ao k = C ~ C - C - C + C C
3 ad bd ac bc do - co In the ideal case, kl = k2 = k3 = 0.
In practice, deviations from this ideal case are determined by the following parameters indicated in Figure 5:
dielectric constants ar~ b~ c~ d wire radii ra', rb', rc', rd' ; outer radii of insulation ra", rb", rc", rd"
~ eccentricities Ra, Rb, Rc, Rd of wire axes ;, .
angular spacing ~a, ~b, ~c, ~d of axial planes.
The conductor insulation according to.the present invention insures the essential constancy of the foregoing para-: . .
meters over the entire length of the cable.
A cable according to the invention can be manufactured in a relatively simple manner and is lighter as well as more flexible than those of the paper-insulated type while being also considerably easier to splice with the aid of automatic equipment.
The risk of unravelling, as can happen with paper wrappings, is eliminated.
', - . . . :" . : .
,: ,, .. , ... . ,, . . : , , : .: . ,.
Telephone cables are always formed from elements consisting of insu]ated wires ~rouped in twos or fours, known respectively as pairs and quads. The pairs may consist of either two coaxial conductors or helically twisted wires. In this latter case they are known as symmetrical pairs. The quads are either formed from four twisted wires (star quad), or from twisted wire pairs which are themselves twisted, and known as D~ (Dieselhorst-Martin) quads or symmetrical pair quads. These pairs or quads form the elementary circuits of a cable. The present invention relates in particular to star quads, DM quads and symmetrical pairs.
The proximity of the conductors grouped in a cable means that the telephone circuits are not totally independent of each ' other. Interactions are produced, and parasite signals may be detected in a particular circuit, generated by the passage of signals over other circuits. This phenomenon is known as cross-talk and is manifested in practice by the awareness of a telephone eonversation transmitted over a neighbouring circuit.
Corss-talk i5 influenced by the electrical resistance of ` the elementary circuits, by the capaeitance of these circuits, and in partieular by their eapaeitance dissymmetry. These same parameters also eontribute to line attenuation, whieh results in a :::
deerease in the sound level of the transmitted eonversation and should of eourse be as low as possible.
; The eleetrieal resistance of the circuit is defined by parameters which can be fairly easily controlled, namely the resistivity of the metal used for the conductor, the constancy of this resistivity along the line, and the conductor dimensions.
The capacitance and capacitance dissymmetries, the influence of which is preponderant in eross-talk questions, depend on the dieleetrie constant of the insulant utilised, which . . .
~ , . .. .
- , ...... - ~ : ' , . : : '' ' : . .
, . . , : :
6~3~
is a measurable and reproducible parameter, but they also depend on other parameters much more difficult to control and which are related to the geometry of the quad. This geometry results from the helical assembly of the quad wires, and it is obvious that it is very difficult to control such geometry with rigorous precision, and in particular to ensure that no displacement of the wires in the quad occurs during the further cable manufacturing operations.
For a long time, cables were insulated with spirally wound paper strip, but this insulating material, which is relatively fragile, of low productivity and leads to complications in splic ing, has now been replaced by plastics insulation applied by extruding machines.
This plastics insulation has the disadvantage of a high-er dielectric constant, which requires the thickness of the insulation to be increased to obtain the same line attenuation.
In addition to these d~fects deriving from the nature of : ;
; the insulation, two other defects may be indicated which derive indirectly from the use of plastics insulation. First, it is difficult to ensure accurate centering of the conductor in the sheath produced by an extrusion machine. Eccentricity of the .:~ I' .
i conductor has repercussions over the entire length of the wire, and creates capacitance dissymmetries. Furthermore, even when this defect is practically non-existant, the stability of the geometry of quads formed from wires insulated by plastics sheaths is poor because of the low coefficient of friction between the sheaths, so that the wires may become displaced and create capacitance dis-,. . .
symmetries, in particular during the cable manufacturing operations which follow the manufacture of the quads themselves.
Finally, and in contrast to paper insulation, plastics insulation offers no protection to the cable against water infil-tration if the cable envelope becomes defective.
- Among the numerous solutions which have been advocated, ~' '.' ~ -2-. .. .
.
it has been proposed in sritish patent No 1,40~,068 to fix cellulose fibres around a plastics sheath to form a hydrophilic region about the sheath, capable of swelling in the presence o~
water, to become a seal which prevents water progressing along the cable. According to this method, the purpose of the plastics - sheath is to insulate the electrical conductor which it envelops, while the purpose of the cellulose fibres is to prevent water in-filtrating along the cable by the hydrophilic proper-ty of the ; cellulose.
The object of the present invention is to improve the capacitance symmetry of telephone circuits, using wires the insulation sheath of which is surrounded by a plurality of fibres.
~ To this end, the present invention provides a telephone ;~ cable element formed from at least one pair of helically twisted electrical conductorscomprising, in combination: a respective insulating sheath enveloping each of said conductors, and a plurality of fibres embedded in the wall of each of said sheaths so that they project all round said sheaths, the lengths of these fibres and their density being chosen so as to maintain between said conductors `- 20 a determined spacing which is a function of the desired capacitance between the conductors, the average length of said fibres and the density at which they are embedded in said sheaths being kept con-stant so that said spacing remains uniform over the entire length of the cable element, the projecting portions of said fibres form-ing members of which the sheath of one conductor is fastened to the sheath of the other conductor by the mutual interpenetration of the fibres of the adjacent sheaths, such that the pitch of the helix is :
kept constant and uniform over the entire length of thecable element.
~ 30 Telephone cable elements constructed in accordance with I the invention have shown that, regardless of the nature of the fibres utilised, the presence of these fibres of given average , ~3~
length embedded in the sheath at a constant density enables a - -spacing to be maintained between the conductors which is a function of the desired capacitance, and to give said capacitance a symmetry which is absolutely surprising, and very difficult to obtain wi-th extruded insulation. Moreover, when bundles and cables are manufactured using pairs of quads according to the invention, it is found that these elements have not undergone any deformation, because of the interpenetration of the fibres in the adjacent regions of the conductors, and in contrast to that which happens with all other known forms of insulation, which allow the twisted conductors to become displaced relative to each other during the further cable manufacturing operations.
The importance of these advantages and of other accompanying advantages will be more evident from the description given hereinafter.
The accompanying drawing represents a diagrammatic illustration by way of example of cable elements according to the presentinvent~ion; In the drawing:
Figure 1 is a perspective view of a pair;
Figure 2 is a cross-section through a quad of ~ ~ -symmetrical pairs; ~
. .
Figure 3 is a cross-section of a star quad;
Figure 4 is a diagram which is useful in defining the ; parameters k which are a measure of capacitance dissymmetries; and :. : :
Figure 5 is a diagram showing the various factors which can modify the value of the aforementioned parameters.
, Figure 1 shows a pair 25 formed from two wires 24 twisted into a helix of constant pitch. Each of the wires comprises a i conductor 2 enveloped by a plastics sheath 19 in which a plurality { 30 of fibres 21 are anchored. The pair 25 is designed to constitute a telephone cable element forming a telephone circuit or line. As can be seen in Figure 1, the fibres 21 which cover the respective ... ..
. ~ .
insulating sheaths 19 mutually interpenetrate in the adjacent parts of the twisted wires. Consequently, these fibres act as distant pieces between the insulating sheaths formed about the conductors 2, the diameter of which in this example is 0.6 mm, the sheaths being preferably of expanded polyethylene about 0.2 mm thick, the avarage length of the fibres then being about 1 mm and their diameter 25 denier. The polyethylene layer ensures good mechanical strength and sufficient electrical strength. The fibres, which are preferably cellulose fibres, have a good insulation resistance when dry, and a low dielectric constant which is less than that of the plastics material alone.
If the surrounding cable envelope (not shown in Figure 1) is ruptured and water penetrates into its interior, the cellulose fibres have a duel function of impeding, by their swell-ing the progression of the water along the cable and, through a lowering of their electric resistance, sharply increasing the leakage current and thus signalling the existance of a defect.
.'~
~ The blocking of the flow by the swollen fibres is highly effective .
and limits the damage to a short length of-cable. The location of the leak can be readily pinpointed by measurements of the current flow and the voltage drop along the line.
Even if the effecti~e length of the projecting fibres varies somewhat about its mean value, the spacing of the conductor cores remains substantially unchanged during handling so that no `~ significant variations in the shunt capacitance between the -conductors occur. Stabilization of this shunt capacitance at a predeterminedmagnitude is essential for the suppression of cross-talk between circuits of a ~uad including the conductor pair of Figure 1, as more fully discussed hereinafter with reference to Figure 4.
In a specific instance, fibres of the dimensions given above have a density of about 400 g/km.
.', .
.
.~ . j , '' .
;, . .
The fact that the sheath is not extruded but is produced by the melting of polyethylene powder, as described in the abovementioned British patent, also contributes to the mainten-ance of the desired symmetry inasmuch as any irregularities in the coating process tend to be distributed at random around the conductor axis; on the other hand, any irregularity of an extrusion nozzle leads to a distinct eccentricity of the sheath. The inter-leaved fibres also resist any relative axial shifting of the conductors which in the absence of the fibres could occur during -handling, thereby unbalancing the circuit.
; Figure 2 shows two balanced pairs 25 of the type illustrated in Figure 1 within a common, flexi.ble envelope ` illustrated diagrammatically at 26.
Figure 3 shows a star quad 25' disposed within an envelope 26; the array 25' consists of four insulated conductors - 24 twisted about a common axis, the conductor axes lying at the : corners of a square, in any transverse plane. In this instance, ~ .
- the fibres 21 interpenetrate not only in the spaces between adjoin- .
.i ing conductors but also in a central channel 27 which would be .; . . ~., . :
. 20 completely empty in a quad composed of conventionally sheathed .
conductors including those with paper wrappings. While such .~
, wrappings could form a barrier between adjoining conductors, they .
would.not:swell sufficiently to block the flow of water in the vicinity of the cable axis. Envelope 26 may, of course, embrace a .
multiplicity of arravs 25 and/or 25'. ..
We shall now refer to Figure ~ for a discussion of the ~
part played by the various shunt capacitances in a quad forming i three signalling circuits as noted above. In Figure 4 the four ~.. -conductors are designated a,b,c and d; the interconductor e Cac, Cbc, Cad and Cbd; and the shunt capacitances with reference to ground are Cao, Cbo, CCO do circuit consists of wires a (outgoing) and b (incoming), the .' ":
., ~ ,.
.. . . . ; . : .. ;. : .
6~
second circuit consists of wires c (outgoing) and d (incoming), and the third or phantom circuit consists of wires a, _ (outgoing) and c, d (incoming). We can then define the cross-talk among those circuits in terms of three parameters, namely a factor k relating to the first and second circuits, a factor k2 relating -to the first and third circuits and a factor k3 relating to the second and third circuits. These parameters are glven by the following equations;
klCaC + Cbd Cbc Cad ':
10 k2bc Cbd Cac Cad 2 ao k = C ~ C - C - C + C C
3 ad bd ac bc do - co In the ideal case, kl = k2 = k3 = 0.
In practice, deviations from this ideal case are determined by the following parameters indicated in Figure 5:
dielectric constants ar~ b~ c~ d wire radii ra', rb', rc', rd' ; outer radii of insulation ra", rb", rc", rd"
~ eccentricities Ra, Rb, Rc, Rd of wire axes ;, .
angular spacing ~a, ~b, ~c, ~d of axial planes.
The conductor insulation according to.the present invention insures the essential constancy of the foregoing para-: . .
meters over the entire length of the cable.
A cable according to the invention can be manufactured in a relatively simple manner and is lighter as well as more flexible than those of the paper-insulated type while being also considerably easier to splice with the aid of automatic equipment.
The risk of unravelling, as can happen with paper wrappings, is eliminated.
', - . . . :" . : .
,: ,, .. , ... . ,, . . : , , : .: . ,.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A telephone cable element formed from at least one pair of helically twisted electrical conductors comprising, in combination: a respective insulating sheath enveloping each of said conductors, and a plurality of fibres embedded in the wall of each of said sheaths so that they project all round said sheaths, the lengths of these fibres and their density being chosen so as to maintain between said conductors a determined spacing which is a function of the desired capacitance between the conductors, the average length of said fibres and the density at which they are embedded in said sheaths being kept constant so that said spacing remains uniform over the entire length of the cable element, the projecting portions of said fibres forming members by which the sheath of one conductor is fastened to the sheath of the other conductor by the mutual interpenetration of the fibres of the adjacent sheaths, such that the pitch of the helix is kept constant and uniform over the entire length of the cable element.
2. An element as claimed in Claim 1, in which the thick-ness of said sheath is of the order of 0.2 mm, the fibre length is of the order of 1 mm and the fibre diameter is of the order of 25 denier, the density of the fibres in said sheath being of the order of 400 g/km.
3. An element as claimed in Claim 1, in which the fibres are hydrophilic.
4. An element as claimed in Claim 3, in which the fibres are cellulosic.
5. An element as claimed in Claim 1, in which the sheaths consist of expanded plastics.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/635,639 US3999003A (en) | 1972-08-18 | 1975-11-26 | Telecommunication cable resistant to water penetration |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1063685A true CA1063685A (en) | 1979-10-02 |
Family
ID=24548569
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA266,318A Expired CA1063685A (en) | 1975-11-26 | 1976-11-23 | Insulated electric wire and method of making this wire |
Country Status (19)
| Country | Link |
|---|---|
| JP (1) | JPS5266965A (en) |
| AR (1) | AR209398A1 (en) |
| BE (1) | BE848815A (en) |
| BR (1) | BR7607733A (en) |
| CA (1) | CA1063685A (en) |
| CH (1) | CH610137A5 (en) |
| DE (1) | DE2653668C3 (en) |
| DK (1) | DK529376A (en) |
| ES (1) | ES453678A1 (en) |
| FI (1) | FI62737C (en) |
| FR (1) | FR2333332A1 (en) |
| GB (1) | GB1565385A (en) |
| IL (1) | IL50958A (en) |
| NL (1) | NL163895C (en) |
| NO (1) | NO144310C (en) |
| PT (1) | PT65869B (en) |
| SE (1) | SE7613112L (en) |
| YU (1) | YU39373B (en) |
| ZA (1) | ZA767035B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ATE470940T1 (en) * | 2004-03-10 | 2010-06-15 | Nexans | MULTI-CORE STRANDING BRACKET |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH560953A5 (en) * | 1972-08-18 | 1975-04-15 | Cossonay Cableries Trefileries |
-
1976
- 1976-11-01 CH CH1372376A patent/CH610137A5/en not_active IP Right Cessation
- 1976-11-18 BR BR7607733A patent/BR7607733A/en unknown
- 1976-11-22 PT PT65869A patent/PT65869B/en unknown
- 1976-11-22 FI FI763354A patent/FI62737C/en not_active IP Right Cessation
- 1976-11-22 IL IL50958A patent/IL50958A/en unknown
- 1976-11-23 GB GB48746/76A patent/GB1565385A/en not_active Expired
- 1976-11-23 FR FR7635254A patent/FR2333332A1/en active Granted
- 1976-11-23 CA CA266,318A patent/CA1063685A/en not_active Expired
- 1976-11-23 DE DE2653668A patent/DE2653668C3/en not_active Expired
- 1976-11-24 ZA ZA767035A patent/ZA767035B/en unknown
- 1976-11-24 DK DK529376A patent/DK529376A/en not_active Application Discontinuation
- 1976-11-24 NL NL7613070.A patent/NL163895C/en not_active IP Right Cessation
- 1976-11-24 SE SE7613112A patent/SE7613112L/en not_active Application Discontinuation
- 1976-11-25 JP JP51140777A patent/JPS5266965A/en active Granted
- 1976-11-25 YU YU2873/76A patent/YU39373B/en unknown
- 1976-11-25 AR AR265605A patent/AR209398A1/en active
- 1976-11-25 NO NO764030A patent/NO144310C/en unknown
- 1976-11-26 ES ES453678A patent/ES453678A1/en not_active Expired
- 1976-11-26 BE BE172761A patent/BE848815A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| FR2333332A1 (en) | 1977-06-24 |
| BR7607733A (en) | 1977-10-04 |
| NL7613070A (en) | 1977-05-31 |
| FI62737C (en) | 1983-02-10 |
| SE7613112L (en) | 1977-05-27 |
| FR2333332B1 (en) | 1981-07-03 |
| DE2653668C3 (en) | 1980-10-30 |
| JPS5266965A (en) | 1977-06-02 |
| NO144310B (en) | 1981-04-27 |
| DE2653668B2 (en) | 1980-03-06 |
| ZA767035B (en) | 1977-10-26 |
| YU287376A (en) | 1982-05-31 |
| AU1986376A (en) | 1978-06-01 |
| AR209398A1 (en) | 1977-04-15 |
| BE848815A (en) | 1977-05-26 |
| YU39373B (en) | 1984-10-31 |
| IL50958A (en) | 1979-09-30 |
| DE2653668A1 (en) | 1977-06-08 |
| ES453678A1 (en) | 1977-12-01 |
| NL163895C (en) | 1980-10-15 |
| PT65869B (en) | 1978-05-17 |
| PT65869A (en) | 1976-12-01 |
| NL163895B (en) | 1980-05-16 |
| FI763354A (en) | 1977-05-27 |
| DK529376A (en) | 1977-05-27 |
| IL50958A0 (en) | 1977-01-31 |
| CH610137A5 (en) | 1979-03-30 |
| NO764030L (en) | 1977-05-27 |
| GB1565385A (en) | 1980-04-23 |
| FI62737B (en) | 1982-10-29 |
| JPS5633804B2 (en) | 1981-08-06 |
| NO144310C (en) | 1981-08-12 |
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