US1730740A - Electric cable - Google Patents

Description

Oct. 8, 1929. J. J. MORRISON ELECTRIC CABLE Filed Aug. 6, 1928 2 Sheets-Sheet mania)": J4M6 MORE/501v;

06L 8, 1929. J MORRISON 1,730,740

ELECTRIC CABLE Filed Aug. 6, 1928 2 Shee ts-Sheet 2 lrwenior:

- .k/VA'S J Maze/50m Patented Oct. 8; 1929 UNITED STATES PATENT OFFICE JAMES J. MORRISON, 0F WORCESTER, MASSACHUSETTS, ASSIGNOR TO THE AMERICAN" STEEL AND WIRE COMPANY OE NEW JERSEY, A CORPORATION OF NEW JERSEY ELECTRIC CABLE Application filed August This invention relates to the manufacture of electric cables and consists of a construction-whereby a cable of superior quality is produced. The invention concerns particularly cables whose conductor or conductors are wrapped with paper or other insulating fabric, such as cambric, the assembled insulated conductor or conductors being impregnated and saturated with insulating compound which may be an oil or similar material, and with a lead sheath overall.

Such types of cables present difficulties in saturation, due to the tightness and thickness of wrapping of insulating'tapes of paper or other material, in removing both air and moisture and in securing thorough and even saturation. J. I

After installation, as the cables are alternately heated and cooled, thesaturating oil expands and contracts and, in so doing, flows into or out of reservoirs provided for such purpose.- The restriction offered to this flow by ordinary insulation often results in high pressures being developed within the cable.

' The object of my invention is to provide a construction of cable which will be more evenly and uniformly saturated when manufac tured, and which will maintain such saturation more uniformly after installation when the cable is connected with such oil supply reservoirs.

These results are secured by perforating the tapes of which the insulation is formed prior to their application to the conductor or conductors in the manner shown by the drawings' submitted herewith, but it is not intended that any particular form or arran ement of the perforations in the tapes be specified.

In the drawing v Figure 1 is a plan of one end of a single conductor cable, partly broken away to show the several elements.

Figure 2 is a cross-sectional view taken on the line IIII of Figure 1,.

Figure 3 is a plan of one end of a multiple round conductor cable, partly broken away to show the several elements.

Figure 4 is a cross-sectional view taken on v the lineIV-IV of Figure 3.

Figure 5 is a-plan of one end of a three-conings, the numeral 1 8, 1928. Serial No. 297,?60.

ductor sector-type cable, partly broken away to show the several elements. r

Figure 6 is a cross-sectional view taken on the line VlVI of Figure 5.

Referring more particularly to the drawdesignates the conductor or conductors with insulation 2 in the form of tapes applied helically, these tapes being perforated, as at 3. Over the insulation of the individual conductor and assembled conductors is shown a perforated metallic tape 4 and l respectively, and a lead sheath 5. In the multiple conductor cables of Figures 3 to 6, the spaces betwen the assembled conductors are filled with bodies of filling material, such as hemp.

By the ap lication of perforated tapes, as shown, or by tapes perforated'in any other form, a body of insulation will be obtained containing a very great number of small reservoirs which will materially assist in the impregnation of the insulation during the perforations facilitate removalof air and moisture for a given vacuum and, in a similar manner during the saturating process, permit the ready ingress of the saturant.

Where presaturated paper, varnished cambric, treated paper or other fabric tape insulation is employed, the use of the perforated tapes ermit of evacuation, dryin and impregnating in the same manner as ca le insulated with untreated paper.

By the use'of such perforations a cable constructed of treated paper and other type of paper insulation will permit of impregnation in the usual manner.

Perforated metal tape or tapes to serve as conductors may be used on any of the above cbnstructions at any point or points of the insulationbetween conductor or'conductors' 1 and sheath, since the perforations permit the saturant to pass readily therethrough.

In any such construction of cable, the respective tapes may be perforated either in whole or in part to give any combination of perforatedand unperforated tapes, and the respectivetapes may be applied in such manner that adjacent convolutions overlap, or abut; or they may have open spaces between.

The use of perforated tapes in construction of the cable insulation will be particularly applicable where hollow core conductor, sheath oil channel construction or combination of these methods are employed in order to permit of drying, impregnation or reimpregnation during and after installation.

During operation in service, cable of such construction will be assisted materially in the maintenance of a uniform impregnation where reservoirs are used for supplying oil to the cable, due to the porous character of the perforated insulation and pressures generated within the cable, will more readily equalize themselves throughout the length of the cable, thus preventing local high pressure spots. v

Throughout the specification and claims the term fabric, describing the insulating tape, is meant to include paper and paper compositions, treated or untreated, textile tapes'of any kind, and any combination of paper and textile products made into tape form and usable as an insulating material.

While I have specific embodiments of my invention it will be understood that I do not wish to be limited thereto since various modifications'may be made without departing from the scope thereof, as defined in the appended claims.

I claim 1. In an electric cable, the combination of at least one conductor, an insulation surrounding said cable composed of at least one layer of perforated fabric, and a perforated metal tape overlying said layer of fabric, said perforations in said tapes facilitating the impregnating of said insulation with fluid insulating compounds.

2. In an electric cable, the combination of at least one conductor, an insulation surrounding said cable composed of a plurality of layers of fabric tapes, at least some of said tapes being perforated, and at least one layer of perforated metal tape overlying said fabric tape, said perforations in said tapes facilitating the impregnating of said insula tion withfiuid insulating compounds. 1

3. In an electric'eable, a plurality of ,conductors, each of said conductors being provided with an insulation composed of a plurality of layers of fabric tapes,

metal tape overlying said fabric tapes on. each of said conductors,

shown and described certain at least some of said tapes being perforated, a perforated and a perforated tape surrounding and binding all of said insulated conductors together, tions in said tapes facilitating the impregnating of said insulation with fluid insulating compounds. I

4. In an electric cable, a plurality of conductors, each of said conductors being provided with an insulation composed of a plurality of layers of perforated paper tapes, a perforated metal tape overlying said paper tapes on each of said-conductors, and a persaid perforaforated tape surrounding and binding all of said insulated conductors together, said perforations in said tapes facilitating the impregnating of said insulation with fluid insulating compounds.

' 5. In a multiple-conductor cable the combination of a plurality of individually insulated metal enveloped conductors cabled within a sheath with filler spaces between, the metal envelope of each insulated conductor being perforated so as to be penetrable by liquid insulating material, and the insulation immediately surrounding each conductor and within the metal envelope consisting of perforated permeable material filled with liquid insulating material, and a flood of liquid under pressure maintained within the filler spaces and said perforations in said metal envelopes and said insulation.

In testimony whereof, I have hereunto set my hand. I JAMES J. MORRISON.

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