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Publication numberUS2536904 A
Publication typeGrant
Publication dateJan 2, 1951
Filing dateJun 24, 1946
Priority dateJan 23, 1942
Also published asDE894862C
Publication numberUS 2536904 A, US 2536904A, US-A-2536904, US2536904 A, US2536904A
InventorsBeuckens Jacobus, Mol Evert Arij Jan
Original AssigneeHartford Nat Bank & Trust Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Cable with air insulation
US 2536904 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

Jan. 2, 1951 J BEUCKENS ETAL (ABLE WITH AIR INSULATION Filed June 24, 1946 I N V EN TORS. c//l COBUS BEUCIQNS BY EI TRTARIJ JAN )VIOL Patented Jan. 2, 1951 CABLE WITH AIR INSULATION Jacobns Beuckcns and Evert Arij Jan Mol, Venlo, Netherlands, assignors, by mesne assignments, to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application June 24, 1946, Serial No. 678,780 In the Netherlands January 23, 1942 Section 1, Public Law 690, August 8, 1946 Patent expires January 23, 1962 3 Claims. 1

The invention relates to cables wherein in connection with their use low dielectric losses and, in addition, a slight mutual capacity between the conductors present therein or a slight capacity between these conductors and an external conductive envelope is desired, such as cables for carrier-wave telephony, for television, for aerials and other purposes.

In order to maintain the said capacity at a low value it has been proposed to constitute the insulation in such cables partly by air. In this connection cables with air insulation wherein use is made of a helically wound thread or ribbon of paper are well-known. Due to the harmful properties of paper, more particularly to the high sensitivity to moisture, these cables exhibit high dielectric losses unless particular precautions against the penetration of moisture are taken, for example by providing a lead sheath.

An appreciable improvement in these respects has been obtained by replacing paper by polystyrene or similar polymerides of arylolefines. In contrast with paper these substances exhibit, however, more particularly at temperatures below C., a great brittleness, which is harmful in the use in cables. This brittleness, which reduces the flexibility of the cables, exists when a thread or ribbon of polystyrene is he.ically wound although in this case the cables are substantially not under strain of bending but are under strain of torsion.

It is 'true that for removing the said drawback it would be possible to utilize the polystyrene in drawn-out condition but at the low temperatures above referred to th s does not reduce the brittleness to an appreciable extent.

It has been found that air-insulated cables of satisfactory flexibility, even at low temperatures, may be obtained by utilizing helically wound threads or ribbons consisting of polyvinylchloride or similar polymerides containing chlorine, such as chlorinated polyvinylchloride and mixed polymerisates on the basis of polyvinylchloride, which contain a softener in so low a percentage that the dielectric losses are lower than about 100 10- measured at a wavelength of from 50 to 200 meters at room temperature. The softeners commonly utilized with the said insulating materia's, such as tricresylphosphate, chlorinated diphenyl, dibutylphthalate and the like enter into account for carrying the invention into effect.

The thread or ribbon may be utilized either solid or hollow or properly profiled and, if de-- sired, provided with inlaid portions either conductive or not. J

With the said dielectric losses sufllciently low for practical appliances the insulation according to the invention is to a high extent resistant to compressive strain and insensitive to moisture.

As appears from the above, the invention is based on the recognition that by utilizing a suitable percentage of the softener it is possible to obtain in a simple manner the said combination of favourable properties. Within the scope of the invention the required percentage of the softener is slightly dependent upon the nature of the polymerisate and of the softener utilized therewith. The upper limit thereof is determined by the requirement about the dielectric losses and the lower limit by the required flexibility, a content of at least about 10% being generally required therefor.

With the cables according to the invention it is further important that the insulation should be non-inflammable and resistant against the effect of light and atmospheric influences. A further advantage is that the insulation is substantially not attacked by aliphatic hydro-carbides, which is important for example in the use as a cable for a motorcar aerial.

The insulation according to the invention may be utilized in bare conductors as .well as in con ductors already provided with an insulating layer while the conductors may be located therein so as to be entirely free or may be locally supported. The heically wound insulation is preferably surrounded by a flexible insulating sheath, for example in the form of foil, which may be surrounded by an external conductive layer which acts as an electric screen, for example by a metal covering or a conductive layer of varnish, which, if desired, may be surrounded in its turn, for ex ample, by a cotton covering.

The invention will be explained more fully with reference to the accompanying drawing.

In this drawing l denotes a copper wire having a. diameter of 0.25 mm., which wire is located freely within a helically wound thread 2 with a thickness of 1.2 mm. which consists of polyvinylchloride which has been plastifled with 15% of diphenylchloride, the thread of polyvinylchloride being wound during this operation on a mandrel of 5 mms. with a pitch of 4 mms. Then there has been proviedd a covering of polyvinylchloride foil 3 which is surrounded successively by a metal covering 4, which acts as a screen, and by a cotton covering 5.

What we claim is:

aeaaeoa 1. An air-insulated flexible cable comprising a tubular flexible insulating sheath, a conductor *element freely disposed within said sheath, and

a helically wound ribbon of insulating material within said sheath, said insulating material comprising a chlorinated polymeride and between apbient temperature.

2. An air-insulated flexible cable comprising a tubular flexible insulating sheath, a conductor element freely disposed within said sheath, and a helically wound ribbon of insulating material within said sheath, said insulating material comprising polyvinyl chloride and about 15% of diphenyl hloride, said insulating material having dielectr e losses less than about 100 1O at wavelengths between'50 and 200 meters measured at the ambient temperature.

3. An air-insulated flexible cable comprising a tubular flexible insulating sheath, a conductive layer on the outer surface of said tubular sheath, a conductor element freely disposed within said sheath, and a helically wound ribbon of insulating material within said sheath. said insulatin material comprising a chlorinated polymeride and a plasticizer in an amount between 10 and 15% of the insulating material, said insulating material having dielectric losses less than about 100x10- at wavelengths between 50 and 206 meters measured at the ambient temperature.



REFERENCES @FEEHD The following references are of record in the file of this patent:


Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1990903 *Dec 27, 1932Feb 12, 1935Carbide & Carbon Chem CorpDenture
US2115214 *Jul 30, 1936Apr 26, 1938Ault & Wiborg CorpCoating composition
US2116643 *Jul 19, 1933May 10, 1938Helge RostElectric cable
US2160904 *Oct 12, 1937Jun 6, 1939Dow Chemical CoPlastic derivatives of vinylidene chloride
US2193613 *Mar 18, 1937Mar 12, 1940Goodrich Co B FPolyvinyl halide compositions
US2197616 *Mar 18, 1938Apr 16, 1940Siemens AgAir-space insulated conductor
US2204737 *Oct 7, 1938Jun 18, 1940Ici LtdManufacture of electric cables
US2252486 *Oct 30, 1937Aug 12, 1941Standard Oil CompanyCoating composition and the like-
US2395872 *May 22, 1943Mar 5, 1946Isenberg Hans DAir-space insulated conductor
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4171868 *Jul 21, 1977Oct 23, 1979The Post OfficeOptical fiber cable
U.S. Classification174/24, 174/29, 174/28
International ClassificationH01B11/18, H01B11/00
Cooperative ClassificationH01B11/1847
European ClassificationH01B11/18D6