USRE30715E - Water blocked electric cables - Google Patents
Water blocked electric cables Download PDFInfo
- Publication number
- USRE30715E USRE30715E US05/957,046 US95704678A USRE30715E US RE30715 E USRE30715 E US RE30715E US 95704678 A US95704678 A US 95704678A US RE30715 E USRE30715 E US RE30715E
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- US
- United States
- Prior art keywords
- cable
- resin
- conductors
- acid
- water
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B7/00—Insulated conductors or cables characterised by their form
- H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
- H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
- H01B7/282—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
- H01B7/285—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable
- H01B7/288—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable using hygroscopic material or material swelling in the presence of liquid
Definitions
- This invention relates to electric cables protected against the entry and migration of water.
- Cables for use underground where water is present in the environment are now manufactured by filling the interstices between and around the conductors with a jelly or greaselike material to protect the polyolefin insulated conductors against contact with water entering the cable and to prevent any water which does come into contact with a conductor from excessively migrating along the conductor.
- a jelly or greaselike material For effective water blockage such a cable must be filled almost 100% which requires a large amount of filler material.
- the jelly or greaselike material is difficult to remove from the conductors during splicing and terminating the cable. It is often necessary to apply the filling compound hot and this tends to degrade the insulation on each conductor.
- the jelly or grease like material also sometimes imparts stiffness to the cable which hampers installation, especially at low temperatures. A further disadvantage is that such materials are flammable.
- the present invention overcomes these disadvantages by providing an electric cable partially filled with a powder material which will block the ingress of water at low temperatures (i.e. ground temperatures).
- the invention further provides an electric cable having a filler which is non-flammable, non-allergenic and non-toxic and which does not produce deleterious by-products when heated.
- the invention consists of an electric cable having a core of a plurality of insulated conductors and a jacket, the interstices between the conductors and within the jacket being at least partially filled with a mixture of water repellant treated calcium carbonate and at least one high molecular weight resin rapidly hydratable to form a viscous solution.
- the conductors are each coated with a hydrophobic liquid.
- FIG. 1 shows a multi-stranded, jacketed electric cable filled according to the invention
- FIG. 2 shows a multi-stranded, sheathed and jacketed electric cable filled according to the invention.
- FIG. 1 shows a cable 10 comprising a plurality of insulated conductors 12 stranded together to form a core enclosed in a jacket 14 of polyethylene or other material.
- the hydrophobic powder is a .[.long chain fatty acid coated.]. .Iadd.water repellant treated .Iaddend.calcium carbonate .[.such as that.].
- .Iadd. which has a surface coating of a long chain fatty acid or modified fatty acid such as lauric acid, myristic acid, palmitic acid, stearic acid, or arachidic acid. Suitable such powders are .Iaddend.sold under the trade .[.mark.]. .Iadd.marks .Iaddend.”Protaxulate” or "Protex E” by Pluess-Stauffer A.G. of France.[., and the.]..Iadd..
- the .Iaddend.hydrophilic powder is a high molecular weight .Iadd.resin, and one such resin is a high molecular weight .Iaddend.polyacrylamide such as that sold under the trade mark "Separan” by Dow Chemical Corporation or "Magnifloc” by the Cyanmid Company.
- .Iadd.Other suitable resins may be a polyacrylamide which has been cross linked by irradiation, an anionic polyacrylamide having an average molecular weight between 2.5 ⁇ 10 6 and 7 ⁇ 10 6 and with between 12% and 28% acrylamide groupings which have been chemically converted to acrylic acid groupings.
- the resin may be an irradiated cross-linked polyethylene oxide or a hydrolyzed starch graft polymer of polyacrylonitrile.
- .Iaddend.It should be noted that the manufacturers of such .[.hydrophilic.]. .Iadd.hydrophobic .Iaddend.powders specify compacting to achieve water blockage but it will be appreciated that tamping of the core filler in the production of a continuous cable would be very difficult to achieve.
- the percentage composition of filler 16 should be between 95% and 70% by weight of the hydrophobic powder and between 5% and 30% by weight of the hydrophilic powder, depending upon the electrical characteristics required of cable 10. The more critical the electrical transmission requirements, the lower will be the percentage by weight of the hydrophilic powder. For instance a telephone cable would require a minimum amount of the hydrophilic powder, i.e. 5%.
- filler 16 of the invention it is not necessary to substantially fill the voids in .[.claim.]. .Iadd.cable .Iaddend.10. It has been found that in certain instances cable 10 will be water blocked when filled only 33% by volume, because of the nature of the reaction of filler 16 to the ingress of water into the core of the cable. When such ingress occurs in sufficient quantity to break down the surface tension of the coated calcium carbonate the polyacrylamide will dissolve rapidly in the water to increase the viscosity of the water. The solution will travel only a short distance along the cable core, depending on the percentage by volume of the filler present in the core and the pressure of the water itself.
- the mixture may fill between 30% and 95% of the total volume of the interstices. .Iaddend.
- a low viscosity paraffinic oil would be suitable for the purpose preferably with a high analine point.
- a shielded cable 20 is formed by applying a core wrap 22 and then a metal sheath 24 between conductors 12 and jacket 14. Before applying core wrap 22, filler 16 is introduced to occupy the voids between conductors 12 as before. After core wrap 22 has been applied a further amount of the same mixture of hydrophobic powder and hydrophilic powder is applied with metal sheath 24 to form a layer 26 interposed between the core wrap and the sheath.
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- Insulated Conductors (AREA)
Abstract
An electric cable having a multi-stranded core of insulated conductors and a jacket, in which the spaces between and around the conductors are at least partially filled with a mixture which forms a blockage to the penetration of water. The mixture comprises water repellant treated calcium carbonate and high molecular weight polyacrylamide resin which do not react with each other or when in contact with water. Preferably the individual conductors are coated with a hydrophobic liquid such as a low viscosity paraffinic oil.
Description
.Iadd.This application is a continuation-in-part of my copending application Ser. No. 556,294 filed Mar. 7, 1975, now U.S. Pat. 4,004,077 issued Jan. 18, 1977. .Iaddend.
This invention relates to electric cables protected against the entry and migration of water.
Cables for use underground where water is present in the environment are now manufactured by filling the interstices between and around the conductors with a jelly or greaselike material to protect the polyolefin insulated conductors against contact with water entering the cable and to prevent any water which does come into contact with a conductor from excessively migrating along the conductor. For effective water blockage such a cable must be filled almost 100% which requires a large amount of filler material. Also, the jelly or greaselike material is difficult to remove from the conductors during splicing and terminating the cable. It is often necessary to apply the filling compound hot and this tends to degrade the insulation on each conductor. The jelly or grease like material also sometimes imparts stiffness to the cable which hampers installation, especially at low temperatures. A further disadvantage is that such materials are flammable.
It has been proposed to replace the jelly or greaselike material with a powder filling which will react with water to form water blockage materials. An example is disclosed in U.S. Pat. No. 3,538,235 issued Nov. 3, 1970 to Ilse Arendt et al assignors to Siemens AG. However, the powder mixture of the Arendt cable swells on contact with water and alters the mutual capacitance of the cable to an inacceptable degree. If a lower concentration of powder mixture is used the swelling of the resin by itself is not sufficient for adequate water blockage.
Another example of a powder filling which swells on contact with water is disclosed in U.S. Pat. No. 3,803,339 issued Apr. 9, 1974 to Speekman where the interaction of the water with the powder also generates a gas which urges the expanded polymeric material into the voids within the sheath of the cable. Here again the composition and the configuration of the core are altered, which adversely affects the mutual capacitance of the core. More specifically the generation of a gas releases electrolytic ions which adversely changes the specific inductive capacity of the separating medium while swelling and gas pressure changes the geometric configuration of the core. Also, the gas-evolving materials may contain allergenic, toxic and hazardous components or they may produce harardous and objectionable by-products. In German Patent No. 2,007,163 dated Sept. 2, 1971 it has been suggested that polyvinyl alchol or polyacrylamide could be used as a swelling agent but certain of those synthetic resins do not swell rapidly enough in cold water to effect a satisfactory water block where the core is only partially filled with a powdered water blocking agent. Since synthetic resins of this type are expensive, it would be uneconomical to pack a cable core fully with such materials.
The present invention overcomes these disadvantages by providing an electric cable partially filled with a powder material which will block the ingress of water at low temperatures (i.e. ground temperatures). The invention further provides an electric cable having a filler which is non-flammable, non-allergenic and non-toxic and which does not produce deleterious by-products when heated.
In its broadest aspect the invention consists of an electric cable having a core of a plurality of insulated conductors and a jacket, the interstices between the conductors and within the jacket being at least partially filled with a mixture of water repellant treated calcium carbonate and at least one high molecular weight resin rapidly hydratable to form a viscous solution. Preferably the conductors are each coated with a hydrophobic liquid.
Example embodiments of the invention are shown in the accompanying drawings in which:
FIG. 1 shows a multi-stranded, jacketed electric cable filled according to the invention; and
FIG. 2 shows a multi-stranded, sheathed and jacketed electric cable filled according to the invention.
The example embodiment of FIG. 1 shows a cable 10 comprising a plurality of insulated conductors 12 stranded together to form a core enclosed in a jacket 14 of polyethylene or other material. The interstices between conductors 12 and jacket 14, and between the conductors themselves, contain a filler 16 comprising a mixture of a hydrophobic powder in the form of water repellant treated calcium carbonate and a hydrophilic powder in the form of at least one high molecular weight resin rapidly hydratable to form a viscous solution. Preferably the hydrophobic powder is a .[.long chain fatty acid coated.]. .Iadd.water repellant treated .Iaddend.calcium carbonate .[.such as that.]. .Iadd.which has a surface coating of a long chain fatty acid or modified fatty acid such as lauric acid, myristic acid, palmitic acid, stearic acid, or arachidic acid. Suitable such powders are .Iaddend.sold under the trade .[.mark.]. .Iadd.marks .Iaddend."Protaxulate" or "Protex E" by Pluess-Stauffer A.G. of France.[., and the.]..Iadd.. The .Iaddend.hydrophilic powder is a high molecular weight .Iadd.resin, and one such resin is a high molecular weight .Iaddend.polyacrylamide such as that sold under the trade mark "Separan" by Dow Chemical Corporation or "Magnifloc" by the Cyanmid Company. .Iadd.Other suitable resins may be a polyacrylamide which has been cross linked by irradiation, an anionic polyacrylamide having an average molecular weight between 2.5×106 and 7×106 and with between 12% and 28% acrylamide groupings which have been chemically converted to acrylic acid groupings. Additionally, the resin may be an irradiated cross-linked polyethylene oxide or a hydrolyzed starch graft polymer of polyacrylonitrile. .Iaddend.It should be noted that the manufacturers of such .[.hydrophilic.]. .Iadd.hydrophobic .Iaddend.powders specify compacting to achieve water blockage but it will be appreciated that tamping of the core filler in the production of a continuous cable would be very difficult to achieve.
The percentage composition of filler 16 should be between 95% and 70% by weight of the hydrophobic powder and between 5% and 30% by weight of the hydrophilic powder, depending upon the electrical characteristics required of cable 10. The more critical the electrical transmission requirements, the lower will be the percentage by weight of the hydrophilic powder. For instance a telephone cable would require a minimum amount of the hydrophilic powder, i.e. 5%.
Using filler 16 of the invention it is not necessary to substantially fill the voids in .[.claim.]. .Iadd.cable .Iaddend.10. It has been found that in certain instances cable 10 will be water blocked when filled only 33% by volume, because of the nature of the reaction of filler 16 to the ingress of water into the core of the cable. When such ingress occurs in sufficient quantity to break down the surface tension of the coated calcium carbonate the polyacrylamide will dissolve rapidly in the water to increase the viscosity of the water. The solution will travel only a short distance along the cable core, depending on the percentage by volume of the filler present in the core and the pressure of the water itself.
.Iadd.The mixture may fill between 30% and 95% of the total volume of the interstices. .Iaddend.
To aid in the production of the filled cable core, and to inhibit the powders of filler 16 from falling out when cable 10 is cut, it is advantageous to wet the surfaces of the insulation of conductors 12 with a hydrophobic liquid which will not produce adverse characteristics to the cable such as stress cracking in a polyethylene jacket. A low viscosity paraffinic oil would be suitable for the purpose preferably with a high analine point.
In the embodiment shown in FIG. 2 of the drawings a shielded cable 20 is formed by applying a core wrap 22 and then a metal sheath 24 between conductors 12 and jacket 14. Before applying core wrap 22, filler 16 is introduced to occupy the voids between conductors 12 as before. After core wrap 22 has been applied a further amount of the same mixture of hydrophobic powder and hydrophilic powder is applied with metal sheath 24 to form a layer 26 interposed between the core wrap and the sheath.
In specific tests three different telecommunications cables consisting of 25 pairs of 19 gauge insulated conductors were filled in the interstices with varying amounts of powder comprising 80% by weight of water repellant treated calcium carbonate and 20% by weight of high molecular weight polyacrylamide resin. The resultant cables had the following characteristics:
______________________________________ Test Results Desired Nominal Level (1) (2) (3) ______________________________________ Filling by bulk 60% 55 57 67 density Average water flow 35 inches max. 14 26 17 in core after 22 days with 3' head of water Average mutual 0.083 ± 0.005 0.080 0.079 0.079 capacitance ______________________________________
Claims (10)
1. An electric cable having a core of a plurality of insulated conductors and a jacket, the interstices between the conductors and within the jacket being at least partially filled with a mixture of water repellant treated calcium carbonate and at least one high molecular weight resin rapidly hydratable to form a viscous solution.
2. A cable as claimed in claim 1 in which the calcium carbonate is surface coated with a water repellant long chain fatty acid or modified fatty acid selected from the group consisting of lauric acid, myristic acid, palmitic acid, stearic acid and arachidic acid.
3. A cable as claimed in claim 1 in which the resin is an anionic polyacrylamide resin with an average molecular weight between 2.5×106 and 7×106 and with between 12% and 28% acrylamide groupings which have been chemically converted to acrylic acid groupings.
4. A cable as claimed in claim 1 in which the resin is a polyacrylamide resin which has been crosslinked by irradiation.
5. A cable as claimed in claim 1 in which the resin is irradiated cross-linked polyethylene oxide.
6. A cable as claimed in claim 1 in which the resin is a hydrolized starch graft polymer of polyacrylonitrile.
7. A cable as claimed in claim 1 in which the mixture fills between 30% and 95% of the total volume of the interstices.
8. A cable as claimed in claim 1 including a core wrap and a metal sheath located between the conductors and the jacket, the mixture being also interposed between the core wrap and the metal sheath.
9. A cable as claimed in claim 1 in which the conductors are each coated with a hydrophobic liquid.
10. A cable as claimed in claim 9 in which the hydrophobic liquid is a low viscosity paraffinic oil.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US05/957,046 USRE30715E (en) | 1978-11-01 | 1978-11-01 | Water blocked electric cables |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US05/957,046 USRE30715E (en) | 1978-11-01 | 1978-11-01 | Water blocked electric cables |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US05/556,294 Continuation-In-Part US4004077A (en) | 1975-03-07 | 1975-03-07 | Water blocked electric cables |
US05/695,845 Reissue US4002819A (en) | 1976-06-14 | 1976-06-14 | Water blocked electric cables |
Publications (1)
Publication Number | Publication Date |
---|---|
USRE30715E true USRE30715E (en) | 1981-08-18 |
Family
ID=25499002
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US05/957,046 Expired - Lifetime USRE30715E (en) | 1978-11-01 | 1978-11-01 | Water blocked electric cables |
Country Status (1)
Country | Link |
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US (1) | USRE30715E (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0096123A1 (en) * | 1982-06-04 | 1983-12-21 | Northern Telecom Limited | Powder filled fiber optic cable |
US5072073A (en) * | 1990-09-19 | 1991-12-10 | In-Situ, Inc. | Cable sealing method and apparatus |
US5095176A (en) * | 1990-06-12 | 1992-03-10 | At&T Bell Laboratories | Aerial metallic shielded cable having waterblocking provisions |
US5218011A (en) * | 1986-03-26 | 1993-06-08 | Waterguard Industries, Inc. | Composition for protecting the contents of an enclosed space from damage by invasive water |
US5256705A (en) * | 1986-03-26 | 1993-10-26 | Waterguard Industries, Inc. | Composition with tackifier for protecting communication wires |
US6326551B1 (en) | 1997-08-14 | 2001-12-04 | Commscope Properties, Llc | Moisture-absorbing coaxial cable and method of making same |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1116175A (en) * | 1965-10-20 | 1968-06-06 | Siemens Ag | Improvements in or relating to electric cables |
US3538235A (en) * | 1967-11-27 | 1970-11-03 | Siemens Ag | Method of making telecommunications cables |
DE2006359A1 (en) * | 1970-02-06 | 1971-08-19 | Siemens Ag | Plastics insulated signal cable |
DE2007163A1 (en) * | 1970-02-17 | 1971-09-02 | Kabel Metallwerke Ghh | Watertight electric cable |
US3711621A (en) * | 1971-02-18 | 1973-01-16 | Gen Cable Corp | Moisture block in sheathed telephone cables |
US3803339A (en) * | 1971-12-17 | 1974-04-09 | Philips Corp | Longitudinally watertight cable |
DE2257133A1 (en) * | 1972-11-18 | 1974-05-22 | Aeg Telefunken Kabelwerke | SYSTEM FOR TRANSMISSION OF ELECTRIC ENERGY |
US3903013A (en) * | 1972-10-19 | 1975-09-02 | Int Standard Electric Corp | Water blocking gel composition |
US3915888A (en) * | 1970-11-06 | 1975-10-28 | Raymond W Hoeppel | Oil base gel having low viscosity before gelation and method for its preparation |
-
1978
- 1978-11-01 US US05/957,046 patent/USRE30715E/en not_active Expired - Lifetime
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1116175A (en) * | 1965-10-20 | 1968-06-06 | Siemens Ag | Improvements in or relating to electric cables |
US3538235A (en) * | 1967-11-27 | 1970-11-03 | Siemens Ag | Method of making telecommunications cables |
DE2006359A1 (en) * | 1970-02-06 | 1971-08-19 | Siemens Ag | Plastics insulated signal cable |
DE2007163A1 (en) * | 1970-02-17 | 1971-09-02 | Kabel Metallwerke Ghh | Watertight electric cable |
US3915888A (en) * | 1970-11-06 | 1975-10-28 | Raymond W Hoeppel | Oil base gel having low viscosity before gelation and method for its preparation |
US3711621A (en) * | 1971-02-18 | 1973-01-16 | Gen Cable Corp | Moisture block in sheathed telephone cables |
US3803339A (en) * | 1971-12-17 | 1974-04-09 | Philips Corp | Longitudinally watertight cable |
US3903013A (en) * | 1972-10-19 | 1975-09-02 | Int Standard Electric Corp | Water blocking gel composition |
DE2257133A1 (en) * | 1972-11-18 | 1974-05-22 | Aeg Telefunken Kabelwerke | SYSTEM FOR TRANSMISSION OF ELECTRIC ENERGY |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0096123A1 (en) * | 1982-06-04 | 1983-12-21 | Northern Telecom Limited | Powder filled fiber optic cable |
US5218011A (en) * | 1986-03-26 | 1993-06-08 | Waterguard Industries, Inc. | Composition for protecting the contents of an enclosed space from damage by invasive water |
US5256705A (en) * | 1986-03-26 | 1993-10-26 | Waterguard Industries, Inc. | Composition with tackifier for protecting communication wires |
US5095176A (en) * | 1990-06-12 | 1992-03-10 | At&T Bell Laboratories | Aerial metallic shielded cable having waterblocking provisions |
US5072073A (en) * | 1990-09-19 | 1991-12-10 | In-Situ, Inc. | Cable sealing method and apparatus |
US6326551B1 (en) | 1997-08-14 | 2001-12-04 | Commscope Properties, Llc | Moisture-absorbing coaxial cable and method of making same |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: NORTEL NETWORKS CORPORATION, CANADA Free format text: CHANGE OF NAME;ASSIGNOR:NORTHERN TELECOM LIMITED;REEL/FRAME:010567/0001 Effective date: 19990429 |
|
AS | Assignment |
Owner name: NORTEL NETWORKS LIMITED, CANADA Free format text: CHANGE OF NAME;ASSIGNOR:NORTEL NETWORKS CORPORATION;REEL/FRAME:011195/0706 Effective date: 20000830 |