US 1995201 A
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March 19, 1935. J. DELON TELEPHONE CABLE WITH STAR QUADS Filed May 10, 1930 Patented Mar. 19, 1935 UNITED STATES PATENT OFFICE Application May 10, 1930, Serial No. 451,470 In Germany May 23, 1929 2 Claims.
In a telephone cable formed of star quads the values of the capacity unbalance both between circuits of the same quad as also between circuits of adjacent quads are smaller and more regular and consequently the telephone transmissions are better, the greater the symmetry of the conductors constituting the quads of the cable.
Fig. 1 shows diametrically in section a star quad; the four conductors are assembled in such manner that their centres occupy the four corners of a square. Such a geometrical arrangement is difficult to maintain in existing manufactures because of the deformation of the theoretical square during the assembling of the four conductors, the reeling of the quads formed and the enclosure of these quads in a single cable.
When telephone conductors insulated with paper with or without air circulation are used even slight deformations are of great importance in view of the proximity of the wires to one an: other.
To avoid such deformation in the course of manufacture it has been proposed to separate the four conductors of one quad by partitions of paper maintaining a constant distance between the conductors, the paper partitions being folded to cruciform shape, the four conductors being located respectively in each of the angles of the cross.
Such an arrangement has the disadvantage of increasing considerably the diameter of the space occupied by a quad and in consequence that of the cable formed by such quads. The cost of such a cable is much greater than that of a cable of existing construction because of its diameter on the one hand and because of the paper partitions on the other.
The star shaped arrangement forming the subject of the present invention permits of avoiding these disadvantages. It is characterized by a central packing formed by a plastic and insulating material filling exactly the central space which is ordinarily left between the four assembled conductors. This packing is introduced during the operation of assembling the conductors. Its volume is such that it produces no increase of diameter due to its presence.
Fig. 2 shows diagrammatically and in section one embodiment constructed in accordance with the invention. The conductors 1, 2, 3 and 4 insulated by a paper covering 5 have the optimum arrangement shown by Fig. 1. 8 represents the central packing filling exactly the space between the four conductors, pairs of which are tangent to one another. These conductors are. maintained in assembled position by a band or covering of paper indicated at 6.
The deformation of such cable in the course of manufacture is reduced to a minimum, the central packing preventing flattening of the cable or the sliding of one pair of conductors in relation to the other which would tend to position the centres of the conductors at the corners of a parallelogram. Moreover the space occupied by such a cable is identical to that of an ordinary undeformed cable.
The central packing 8 may be formed of any suitable insulating material having a low specific inductive capacity such as paper, jute, cotton or the like and preferably by paper of the same composition as that of the insulating covering 5.
This packing may be formed either by a round paper string loosely constituted so as to assume the form of the central curvilinear quadrilateral at the moment of the passage of the conductors through an assembling machine or by a string of a plastic material to which has previously been imparted a section corresponding to this quadrilateral form so that it fills exactly the central space.
Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:
1. Star quad for telephone cables, the conductors of which are insulated with air-filled paper sheaths, the sheaths being circular and tangent two by two, the said quad comprising a separator packing filling practically the space between the sheaths, the compressibility of this packing being equal to that of the paper sheaths, in order that a crushing of the packing cannot take place without a corresponding crushing of said sheaths.
2. Method of manufacturing a star quad for telephone cables, said quad including paper-insulated conductors and a packing separator between the conductors, comprising insulating the conductors by means of dry-air-filled paper sheaths, forming a loosely wound paper cord, and assembling the conductors around said cord in such a manner that said cord is crushed by the paper sheaths and adapts itself to the central space between the sheaths, whereby when said cord has adopted the shape of said central space its compressibility is equal to that of the paper sheaths.