US3263024A

US3263024A - Cable valley filler

Info

Publication number: US3263024A
Application number: US375235A
Authority: US
Inventors: Hirsch Felix
Original assignee: General Cable Corp
Current assignee: General Cable Corp
Priority date: 1964-06-15
Filing date: 1964-06-15
Publication date: 1966-07-26
Anticipated expiration: 1983-07-26

Description

July 26, 1966 F. HIRSCH 3,263,024

CABLE VALLEY FILLER Filed June 15, 1964 WAX DISPERSION SPRAYED CREPED PAPER I I 28 I CREPED PAPER INVENTOR I LLMA, QM MAM ATTORNEYS.

United States Patent 3,263,024 CABLE VALLEY FILLER Felix Hirsch, Cambria Heights, N.Y., assignor to General Cable Corporation, New York, N.Y., a corporation of New Jersey Filed June 15, 1964, Ser. No. 375,235 8 Claims. (Cl. 174-116) This invention relates to improvements in electric cables and more particularly to low voltage cables that have water repellant paper fillers in the valleys between insulated conductors.

Multiple conductor electric cables commonly have the valleys between the insulated conductors filled with paper, jute, or other material to provide a round contour over which the outer covering or sheath of the cable is applied. It is important, however, to prevent the paper, jute or other filler material from acting as a wick and conveying moisture longitudinally of the cable. Where paper has been used as the tiller it has been conventional pract-ice to prevent such wick action by using a relatively hard paper which is immersed in wax prior to being twisted into a filler strand or cord.

Such twisted paper filler strands are hard and have a limited deformability, and in order to provide a substantially round contour for the cable it often is necessary to use a number of them. It has been necessary to have a number of different sizes of fillers for different sizes of cables, and for cables having different numbers of conductors and resulting differences in the shapes and sizes of their valleys.

It is an object of this invention to provide an improved cable of the type having a paper filler in the valleys and an improved method of making such cable. It also is an object of this invention to provide an improved valley filler and method.

Contrary to the usual practice, this invention uses creped paper for the valley filler instead of kraft paper. Creped paper has been considered unsuitable for such use in cables where wick action must be avoided. In fact, creped pap-er has been used in the past as a valley filler only in oil-filled cables where the wick action was desirable, as in the Branthwaite Patent 1,886,786, November 8, 1932, where it is explained that with creped paper the oil becomes more quickly distributed through the cable. In cables that are filled with insulating oil or other fluid insulation it is known to provide a channel in the cable to facilitate the fiow of the oil or other fluid lengthwise through the cable.

The cable with which this invention is concerned involves just the opposite considerations. Travel of moisture or other liquid, if it gets into the cable, must be prevented or limited. The valley fillers must be constructed of material which will not operate with a wick action to distribute moisture length-wise within the cable. Creped paper cannot be immersed in wax and then gathered to form valley fillers in the way in which hard kraft papers are treated because the creped paper will take up an excessive amount of wax and it is of toolow tensile strength to be for-med into a suitable cord or strand for use in a valley of an electric cable.

This invention involves the novel concept of using creped paper which is much lighter, more flexible, and more resilient than ordinary kraft paper as a valley filler and imparting the necessary water repellant quality to the creped paper by applying wax which is sprayed onto the paper instead of immersing the paper in wax. By this Patented July 26, 1966 ice method the amount of wax on the paper is limited and there is no filling of the small crepe valleys of the creped paper with wax. However, the wax sprayed onto the surface of the paper covers the entire surface and after the paper has been gathered and twisted into a filler strand or cord the wax penetrates the paper and is present in sufficient quantity to prevent wick action. It has been found that the wax can be most easily applied in the necessary small quantity by spraying it onto the creped paper in the form of a water dispersion before the paper is folded or gathered. In the preferred embodiment of the invention the amount of wax applied is approximately three to four percent of the weight of the paper with the wax on it, after the water has evaporated.

The invention has several important advantages. One is that the creped paper has added volume and that a 16 lb. creped paper can be used in place of 30 to 40 lb. kraft paper fillers which are not creped. Another advantage is that the amount of wax used on the creped paper is much less than that used on the kraft paper which has been immersed in a wax bath prior to twisting it into a cord or strand. This results in a substantial saving in material which makes the cable less expensive to manufacture and which also makes the cable lighter in weight. For example, one cable valley filler made in accordance with this invention weights 5 lbs. per thousand linear feet as compared with 9.6 lbs. per thousand linear feet for comparable conventional kraft paper valley filler.

In addition to the advantages of being less expensive and lighter in weight, the electric cable made in accordance with this invention actually is better cable. The valley fillers made of the creped paper are soft and more forma-ble than the valley tillers made of the hard kraft paper immersed in a wax bath. Because of this softer and more forma-ble characteristic the assembly of insulated conductors and valley filler-s takes the desired round shape more easily and forms a smoother and better final product.

Other objects, features and advantages of the invention will appear or will be pointed as the description proceeds.

In the drawings, forming a part hereof, in which like references characters indicate corresponding parts in all the views:

FIGURE 1 is a diagrammatic view showing a multiconductor electric cable with the outside sheath removed for part of the length and with the conductors and valley filler-s separated to show the various parts of the assem- FIGURE 2 is an enlarged sectional view taken on the line 2-2 of FIGURE 1; and

FIGURE 3 is a diagrammatic view showing the way in which the filler material is made in accordance with this invention.

In the illustrative embodiment of this invention an electric cable indicated generally by the reference character 10 includes three

electrical conductors

11, 12 and 13 surrounded by individual walls of suitable electrical insulation 15 and enclosed within an outer sheath 17 of electrically insulating material. The outer sheath 17 may be moistureproof or waterproof for use in underground installation. The

insulated conducbors

11, 12 and 13 are located adjacent to one another and preferably touch one another along lines of adjacency designated by the reference characters 21.

There are several valley fillers 23 located in each of the valleys between the insulated conductors and out- Wardly of the lines of adjacency. These valley fillers 23, originally round or oval in shape, are distorted as necessary to fill the valleys and make the assembly of the insulated conductors and the valley fillers substantially circular, so as to fill the space within the sheath 17.

While it is desirable that the valley fillers distort and compress to the exact cross section of each valley, it is not essential that they fill the valley all the way to the line of adjacency 21 because the fillers pressing against each other and against the sides of insulated conductors will form a barrier to the entrance of any Water into the interior of the assembly even though they do not reach all the way to the vertex of the angle formed by the insulated conductors at the points of adjacency. However, it is desirable that the fillers should reach into the vertex of these angles at frequent locations so as not to leave an unobstructed passage lengthwise of the cable for the travel of any moisture which may enter at the end of the cable. The actual cross section of each of the valley fillers 23, in the completed assembly, will vary somewhat at different locations along the length of the cable depending upon how they are pressed into the valleys and their relation to one another at the time of distortion into the space which they are to fill.

The valley fillers 23 are originally round or oval in cross section and since there are limits to which the shape can be distorted it is usual to employ a plurality of fillers in a valley so as to fill the valley with less distortion of the shapes of the individual fillers. With conventional fillers it has been the practice to employ nine different sizes of fillers for various valleys on different sizes of cable, but with this invention it is sufficient to have only three sizes of fillers. This saving is because of the greater softness and compressibility of the creped paper fillers.

Comparative tests have been conducted on the lightly waxed, creped paper filler of the present invention and heavily waxed kraft paper filler widely used in cable manufacture. The following table lists data obtained using a Randall Stickney gage with a in. diameter pressure foot at room temperature and measuring the deformation seconds after the application of the load:

2. Dimensions, approximate:

Kraft-.20 x .13. creped-.23 x .10.

The above data indicates that the lightly waxed creped paper filler deforms about twice as much as the more heavily waxed kraft paper filler.

FIGURE 3 is a diagrammatic showing of the way in which one of the fillers 23 is manufactured. A strip of creped paper 28, for example 5 inches wide is sprayed with a water dispersion of wax from a spray nozzle 30. The dispersion is preferably applied as a fine mist or fog and it is, of course, desirable to apply as little Wax as necessary for adequate water repellency.

An anionic dispersion of paraffin wax such as is avail- .able from Nopco Chemical Company is suitable, for example. The wax itself may be the same as the wax used in treating kraft paper by the immersion procedure. The temperature at which the dispersion is sprayed onto the creped paper should be such as to prevent the paraffin from solidifying and separating. This temperature may be room temperature, but it has been found that a temperature of about 180 F. gives very satisfactory results. As previously explained, it has been found that wax applied by a fine spray to the surface of the creped paper is in suflicient quantity if the weight of wax is between three and four percent of the weight of the combined wax and paper after the water of the dispersion has evaporated. The dispersion partially penetrates the paper as it is sprayed on. This does not leave the paper covered with a continuous coating of wax and substantial quantities of the interstices of the creped paper are not filled With wax. The paper is gathered and twisted While wet to form a cord 32, as indicated in FIGURE 3. The amount of twist may vary, but about six turns per foot gives a satisfactory product. This causes further penetration and distribution of the wax into the paper and over its surface. The contact between wax covered areas of the gathers and adjacent areas form barriers which effectively close off against moisture transfer any longitudinally extending open spaces which may exist within the twisted cord 32.

The creped valley fillers of the present invention may be made from 16 pound ream weight paper as compared with 30 to 40 pound kraft papers required [for impregnated fillers. It has been found that valley fillers made as herein described are adequately water repellant and will not permit water to travel along their length by wick action. More wax can be used, but it is unnecessary and adds both cost and weight. In the creped paper fillerof this invention the wax comprises 3 to 4% of the weight of the filler, whereas in the Wax impregnated kraft paper the wax comprises 15 to 20% of the Weight of the filler. Because of the lower weight and the greater compressibility of the creped paper filler the weight of the filler per foot of cable is substantially reduced, for example from 9.6 pounds to 5 pounds per 1000 feet in one cable.

This invention may be variously modified and embodied within the scope of the subjoined claims.

What is claimed is:

1. An electric cable construction including a plurality of conductors each of which is covered with a layer of electrically insulating material, the conductors being located adjacent to one another and with valleys extending outward from the lines of adjacency of the insulated conductors, fillers in the valleys including cords made of creped paper having wax on the surface thereof and at least some of the interstices of the creping being free of wax with resulting saving in weight and improved flexibility of the filler, and an outer sheath covering the assembly of conductors and valley fillers and holding the assembly packed together to a smooth rounded contour.

2. The electric cable construction described in claim 1 characterized by the creped paper being twisted to a relatively loose and compressible cord.

3. The electric cable construction described in claim 2 characterized by there being at least three conductors and there being a plurality of fillers in each of the valleys.

4. The electric cable construction described in claim 3 characterized by the creped paper having sufficient wax to prevent each filler from acting as a wick for moisture, and the sheath being of waterproof material for use underground.

5. The electric cable construction described in claim 4 characterized by the wax on the creped paper constituting approximately three to four percent of the filler, by weight.

5 6 6. The electric cable constr ction described in claim 5 References Cited by the Examiner ggatlrlacgfigltsi by the fillers being dry and closely packed UNITED STATES PATENTS 7. A lightweight water repellant cable valley filler 809,312 5/ 1904- Lougee 156-55 comprising creped paper having wax on the surface of 5 1,282,208 6/1917 Fisher 15655 the paper and at least some of the interstices of the 2,185,558 2/1935 Lunsford 174-116 creped paper free of wax, the paper being gathered trans- 2,230,888 7/ 1938 Lamela 174-116 versely and having a cross section of a cord.

8. The lightweight valley filler described in claim 7 LEWIS H. MYERS, Primary Examiner. characterized by the paper being twisted to hold the 10 ROBERTK SCHAEFER Examiner gathers against separation and to maintain the diameter of the cord. H. HUBERFELD, Assistant Examiner.

Claims

1. AN ELECTRIC CABLE CONSTRUCTION INCLUDING A PLURALITY OF CONDUCTORS EACH OF WHICH IS COVERED WITH A LAYER OF ELECTRICALLY INSULATING MATERIAL, THE CONDUCTORS BEING LOCATED ADJACENT TO ONE ANOTHER AND WITH VALLEYS EXTENDING OUTWARD FROM THE LINES OF ADJACENCY OF THE INSULATED CONDUCTORS, FILLERS IN THE VALLEYS INCLUDING CORDS MADE OF CREPED PAPER HAVING WAX ON THE SURFACE THEREOF AND AT LEAST SOME OF THE INTERSTICES OF THE CREPING BEING FREE OF WAX WITH RESULTING SAVING IN WEIGHT AND IMPROVED FLEXIBILITY OF THE FILLER, AND AN OUTER SHEATH COVERING THE ASSEMBLY OF CONDUCTORES AND VALLEY FILLERS AND HOLDING THE ASSEMBLY PACKED TOGETHER TO A SMOOTH ROUNDED CONTOUR.