US1878169A - Terminal - Google Patents

Description

sept. zo, 1932.

- A. M MYI/ERS 1,878,169

v TERMINAL Filed Apri; 1ol 192e ITI Il 7% f Patented Sept. 20, 1932 N UNITED STATES ylaaTENT OFFICE ALEXANDER M. MYERS, OF WILKINSBURG,

PENNSYLVANIA., .ASSIGNOR, BY MESH] ASSIGNMENTS, TO GENERAL CABLE CORPORATION, A CORPORATION F NEW JERSEY TERMINAL Application illed April 10, 1926. Serial No. J101,113.

My invention relates to improvements in 4terminal structures for electric cables, and

specifically to improvements in such a terminal as that shown and described in Letters Patent of the United States No. 1,563,946, granted December l, 1925, on the application of Ralph W. Atkinson.

In the accompanying drawing Fig. I is a view in medial and longitudinal section of a terminal structure` embodying my invention; Fig. II is a fragmentary view on corresponding section, illustrating a modifcatio Referring first to Fig. I, av cable end is shown from which the lead sheath 1 and the machine-laid insulation 2 have been cut away at successively less intervals, exposing the conductor 3. The conductor at its exposed end is electrically united, as by a sweated-on sleeve 5, to another conductor 4, which by way of example may be understood to be an aerial line wire. It is this union which is to be protected.

The terminal casing includes a sleeve-like body 2O of insulating material such for ex ample as porcelain, provided with a thimble 21 of metal, capable of being shaped to and united uponthe cable sheath, as by the wiped solder joint 22. The drawing indicates that the body 2O may be externally petticoated in well-known manne'r and for manifest ends, and it further indicates that this body may be built -up of sections, suitably united.

Within the casing, and more particularly within the thimble 21 a screen 9 of conducting material surrounds the cable, end; it is united electrically with the cable-sheath, and it flares from its point of union at the cut-away end of the cable sheath longitudinally of the cable and toward the union of conductors. A plurality of cylinders 6, 7, 8, etc. of vrigid insulating material and of increasing diameter in the succession indicated, coaxially surround the cable end; and these cylinders at one end contact withv and 1ndeed are borne by the 'screen 9. In the asv sembled structure all the space within the casing, including of course the spaces between the lcylinders and between them and the cable end within and the casing without, are filled with insulation applied in liquid condition. l

My invention relates to structural features which render a terminal having these characteristics easy of` assembly, and that with accuracy. The preformed cylinders 6,

7, 8, etc. are in theshop assembled with and secured to the preformed screen 9. The 'screen 9 may be faced with a layer 91 of insulation upon which the cylinders imme- 00 diately bear and to which they are immediately secured. The workman in the iield is furnished with two unitary parts the casing, including sleeve 20 with thimble 21'remov-v ably attached to it, and the screen 9 to which 66 already the set of cylinders 6, 7, 8, etc. has been secured.

In making installation the cable end is first prepared by the cutting away of the sheath and of the envelope of machine-laid insulation to the proper distances, andthe thim ble 21, separated from the sleeve-like bod l 20, is slipped over the cable. end and slid bac so as to` be temporarily out of the way. The edge of the cable sheath is then prepared by 78 flaring and rounding, and then the screen 9 with the set of cylinders which it carries, is slipped to place, its inner edge resting within the flared edge of the cable sheath. The contact at this point may be made secure, both 80 electrically and mechanically, in suitable manner. The thimble 21 is then advanced and secured .to the sheath, as by the' forming of the wiped solder joint 22 (equivalent securing devices are known to the art; I show a/wiped solder joint by way of example). ,The sleeve-like member 20 is then' applied and secured to Ythe thimble 21 in sultable manner, as by bolts 23, with a asket 24 between the meeting faces. The ling of the I0 installation in the ield be `be permissible.

edge is secured to a fixed support, and the strains tending to discharge casing with Yinsulation in liquid condition and the closure of the casing above are matters well-known to the art, and since they do not directly concern my invention, and as understanding o my invention may be got regardlessof them, I have not included in the drawing a showing of those matters.

It will be observed of the screen 9 that, arranged within thimble 21 it extends throughout substantially the length of the thimble and to the line of union between thimble and a body 2O of insulating material. As specifically shown in Fig. I, the screen 9 extends beyond the line of union alluded to and for appreciable distance within the bore of body 20. This screen 9 so arranged becomes the strain-limiting member; by its presence it removes thimble 21 from consideration as a factor in the problem of electrical security, and leaves the thimble to be considered as a mechanical part merely of the structure. It will further be observed of the screen 9 that extending as it is shown to extend beyond the end of thimble 21 and, when the parts are assembled, into the space within the sleevelike body 20, it affords the desired security, even though such variation as is incident to 'found in the relative positions of the parts. Under conditions of installation it is impracticable to define with minutest precision the interval from the cut-away end of the cable sheath at which the thimble is secured, and in the assembly some small range of variation must The thimble 21 at its outer free edge of screen 9 is within the range indicated variable in its position relative to the precisely located thimble and the body 2O which the thimble carries. This arrangement of the parts-the screen 9 extending beyond the end of thimble 21 and into the space within the sleeve-like body 20-makes allowance for such variation, and within practical limits affords a secure and satisfactory structure, whatever the amount of variation in the particular installation may be.

The drawing indicates that the flaring shape Aof the screen 9 may be so far modilied as to aiiord surace-to-surface engagement of the screen externally upon the outermost of the applied cylinders. By such expedient and by other expedients known tothe art the cylinders 6, 7, 8, etc. may be secured to screen 9 so as to constitute with it a unit for purposes of field assembly,and a unit which in the assembly will in allits parts come accurately to place.

It will be perceived that the cut-away end of the cable sheath (considered as a conductor) is prolonged in a double-walled strueture, the member`9 constituting theinner wall and the member 21 the outer; of this' double-walled structure the inner wall performs the Yelectrical oilice of limiting the either through orover the surface of the insulation, while the outer wall performs the mechanical oices oclosure and support.

' In the modification shown in Fig. II the screen 9a is not prolonged to the degree already indicated in describing the showing of Fig. I. In this case the screen is of such extent that in the assembly its otherwise free edge comes to position adjacent the line of union of thimble with sleeve-like body 20. At this edge the screen 9a is more abruptly flared and its maximum diameter is substantially equal to the interior diameter of the thimble. The thimble however is prolonged, in an extension which when the parts are assembled faces the adjacent portion of the bore ofthe body 20. In this arrangement the screen 9a serves as before to limit stresses tending to electrostatic discharge, throughout that portion of the structure where stress is great, while the prolongation of the thimble within the bore of the insulating body 20 becomes in that portion of the structure where stress is small the stress-limiting member. The flaring of screen 9a to the internal diameter of thimble 21a makes for facility in assembly and securityV in service.

Fig. II serves further to indicate that the flare, which in Fig. I is shownto be at uniform rate from the inner end of screen 9 outward, till it comes largest tube 8, may be at a varying rate, and specifically may be at an increasing rate from the smaller`end of the screen outward.

I claim as my invention:

1. In an electrical installation the tion witha cable comprising an insulated and metal-sheathed conductor, of a terminal structure comprising a casing including a sleevelike body of insulating material and a metal thimble hermetically united end-to-gend, means securing the thimble mechanically upon the sheath of the cable end` the cable sheath terminating within said casing short of the sleeve of insulating material leaving the cable insulation exposed within said thimble and sleeve.. and a preformed flaring metal screen applied to the cable end within the said casing and at its inner end engaging the end of the cable sheath, the said thimble and the said screen engaging the cable sheath each independently of the other, the said screen, when the parts are assembled, flaring to substantially its maximum diameter within said thimble short of said sleeve and extending beyond the said thimble and into the said sleeve.

2. In an electrical installation the combination with a cable comprising an insulated and metal-sheathed conductor, of a terminal structure comprising a casing including a sleevelike body of insulating material and a metal thimble hermeticallv united end-to-end, means securing the thimble mechanically upon the sheath of the cable end, the cable to the diameter of the combinaof the cablesheath, the said thimble and the said screen engaging the cable sheath each independently of the other, the said screen, when the parts are assembled, flaring to substantially its maximum diameter within said thimble short of said sleeve and extending beyond the said thimble and into the said sleeve, and a plurality of radially spaced, coaxial, insulating cylinders integrally secured to saidl flaring exposed `cable insulation.

3. In an electrical installation the combination with a cable comprising an insulated and metal-sheathed conductor, of a terminal structure comprising a metal thimble secured mechanically upon the sheath of the cable end, the cable sheath terminating within said thimble leaving the cable insulation exposed, a preformed flaring screen of conducting material bearing integrally and co-axiall withl itself a plurality of concentric cylindyers of insulating material applied to the unsheathed cable end within the thimble, the said flaring screen engaging the end of the cable sheat independently of the thimble and extending, when the parts are assembled, from the cable sheath through and beyond the end of said thimble, and an insulating sleeve united endto-end with said thimble to complete an enclosing casing for the terminal.

4. In an electrical installation the combination with a cable comprising an insulated and metal-sheathed conductor, of a terminal structure comprising a flaring thimble secured the sheath of the cable end, the cable sheath terminating within the said thimble, a sleevelike body tially the same inside diameter as the maxi# mum inside diameter of said thimble secured to the larger end of said .thimble and in axial alignment therewith, a group of radiallyspaced, conrentric, cylindrical, insulatin members mechanicallv united to form a unit adapted to be slipped over that portion of the uns eathed cable within the thimble an'd sleeve, said unit, when positioned, extending within said thimble and said sleeve-like body of insulating material with said c members extending in both directions from the joint between said thimble and said sleevelike body of insulating material and at both ilarin the ca lends progressively the inner member to the outer member, Aand a metal screen connected to the end of of the cylindrical ins ating members.

article of manufacture for use in ,ahigli voltage terminal structure comprising, I

mechanicallv at its smaller end upon of insulating material of substan-v in combination, a flaring metal sleeve having at its larger end a cylindrical extensionand a plurality of radiallyspaced concentric c liiidrical insulating members mounted within and mechanically secured to said sleeve with jacent the flaring surface of the sleeve, the ends of said cylindrical insulating members the ends'oftlie said cylindrical members adextending beyond the cylindrical extension of the flaring sleeve progressively decreasing in length from the inner nicmberto the outer member.

A In testimony whereof I have hereunto set my hand.

ALEXANDER M. MYERS.

screen and surrounding they ylindrical decreasing in length from I le sheath and engaging the innerends

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