US1718920A - Electrical cable - Google Patents

Description

June 25, 1929 io; A. FREDERlcKsoN ELECTRICAL CABLE:l

Filed. Sept. 7, 1926 /N l/E/VTOR @m 0a, yum

BY M. 36@

ATTQ/QNEY CII Patented June 25, 1929.

UNITED STATES PATENT v'oFEicE OTTO A. FREDERICKSON, OF WETHERSFIELD, CONNECTICUT, A SSIGNOB TO THE WIRE- MOLD COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OF CONNECTICUT.

` v ELECTBIAL CABLE Application led September 7,'1926. Serial No. 133,959.

This invention relates to a novel insulating...

material for electrical conductors. y

Insulated electrical conductors as now ex tensively employed in wiring buildings for electric light circuits and for other. purposes, are commonly formed of a metallicconductor v about which a jacket of rubber is provided and over the rubber jacket is braided or woven a tubular covering. This tubular covering may in turn be protected by a metallic or nonmetallic outer jacket.

The rubber jacket 'possesses good insulating properties but does. not afford good mef chanical protection and the bralded or woven covering is therefore relied upon to protect the rubber jacket from injury and also to increase the electrical protection of the conductor. This protecting covering should therefore be made of strong, durable, nonconducting material, and the cost of such covering should be as vlow as other requirements will permit.

The present invention therefore contemplatesth'e use of a novel material in forming a protecting covering for electrical .conductors, and which possesses various advantages over the cotton andother spun fibres commonly employed heretofore in the construction of such covering; and in accordance with the present invention the insulating covering which may bebraided or woven is formed, at

y least in part, of narrow strips ofpaperthat may be-cut from a sheet of tough, relatively thick paper and introduced directly into the tubular fabric. without being previously twisted or folded. i

A protecting covering formed of these narrow, untwisted strips of paper is extremely tough and durable, possesses excellent insulating propertiesand may be constructed at' very low cost.

The various features of the present invention will be best understood from the 'following description when readin connection with the accompanying drawings, illustrating one embodimentA of the invent1on:-"

In the y drawingsfz-f y "Fig, 1 is a perspective view of an insulated '-electricalcable embodyingjf-the features of the invention;

Fig. 1;

Fig. 3 on an enlarged scale is a perspective View of one of the insulated conductors of Fig. l;

Fig. 4 is a transverse sectional view of Fig.' 3 and Fig. 5 is a perspective view of a paper strip employed in theconstruction of the in' sulating covering.

An insulating covering constructed in ac-A cordance with the present invention may be employed in the manufacture of different types of insulated electrical cable, and is shown in the drawings as applied to a two- 'conductor cable adapted for use in wiring buildings' for the installation of electricY "lights Each ofthe conductors 10 of this cable isl provided with an insulating jacket 1'1 that may be formed of rubber. About each jacket y1l is provided a protecting cover- `ingl12 which is shown as formed of braid constructed in accordance with the present v invention.

About the braid 12 of each conductor, in

the construction shownis wrapped a series of strands 13 placed spirally about the braid, and the insulated conductors thus formed are enclosed and united by the outer jacket 14. The fillers 15 are laid in the valleys at the opposite sides of the conductors to fill up the air spaces between the conductors and outer jacket.

In electrical cables of .the type shown in Fig. 1 of the drawing the construction of the first layer 12 is particularly important, because this layer should furnishthe maximum of protection to the rubber jacket 11 while -at the same time its size should be kept down to the minimum, and this layer should be sufficiently flexible to withstand sharp bends without injury and withoutrausing substantial openings to occur between the strands forming' the layer. F urthermre, thestrands of which the layer 12 4are formed should be so interwoven or braided that they will not unravel when the cable is out.

The .above requirements are well met when the layer 12 isc'onstructed in accordance with Ythe present invention, and in carrying out Fig. 2 is a transverse sectional view of this invention the layer 12 is made up of the paper strands 16 that extend about the couductor l0 in one direction and are inter-braided with the strands 17 that extend in the opposite direction.

The strands'l constitute untwistcd and lunfolded strips of paper which may be cut from a sheet of high quality stock paper having the desired toughness and a thickness that is equal to the thickness of the strips 16 into which the sheet is cut. ness of the strips 16 may of course be varied as desired, but it has been found from experience that strips of paper .015 in thickness by .02 in Width produce a satisfactory covering for the rubber jacket 11.

A sheet of paper having the desired thickness and tensile strength can be cut with a high degree of accuracy and Without waste into narrow strips 16 of the desired Width, and these strips can be taken directly from the slitting machine and Wound on tubes ready for use in a braiding machine or circular loom, The binding strands 17 may be formed of cotton and are smaller and more flexible than the p aper strands so that they readily bend aroundv the paper strands and bind the paper Strandsl in place side by side in edge contact with each other to form an extremely tough and durableprotecting covermg.

If desired the outer jacket 14 may also be formed of a braid made up of untwisted paper strands 16 that are interbraided with the binding strands 17, and in some ca-ses the spirally Wound strands 13 may also be formed of narrow strips 'of paper.

It will be apparent from the foregoing that the untwisted and unfolded strips of paper 16 may be easily and quickly produced by a single operation, since all that is neces- The Width and thicksary is to cut the strips 16 having the desired Width from a sheet of tough, strong stock paper having the required thickness.

What is claimed is 1. A protecting jacket or covering :for electrical conductors formed of narrow untwisted and unfolded strips of tough paper that are cut from a sheet of paper having the thickness of the individual paper strands forming the braid and which are interbraided with binding strands to form a tubular jacket or covering.

2. A protecting jacket or covering for electrical .conductors formed of narrow, untwisted and unfolded strips of tough paper that are cut from aj sheet of paper having the thickness of the individual paper strands of the jacket or covering and which are interlocked with binding strands to form a tubular jacket or covering.

3. An insulated electrical conductor, comprising a metallic conductor having a protecting jacket of tubular fabric formed of internieshing strands one set of Which strands is formed of narrow untwisted and unfolded strips of tough paper that are cut from a sheet of paper having the thickness of the individual paper strands embodied in the fabric. L

4. A protecting jacket or cdvering for elec` trical conductors formed of narrow untwisted and unfolded strips of tough paper that are cut from a sheet of paper having the thickness of the individual lpaper strands embodied in the jacket or covering and which are held side bv side in edge contact with each other by smaller and more iexible binder strands to form a tube.

' In testimony whereof, I have signed my name to this specification.

OTTO FREDERICKSON.

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