US 3384861 A
Description (OCR text may contain errors)
D. M. PHILLIPS LOADBREAK DEVICE Filed Aug. 25, 1966 May 2l, 1968 mfMw WM 4 M ,iwi .i #M mw Unite This invention pertains to electrical distribution systems and, more particularly, to a loadbreak device for use in such systems.
The loadbreak device of the present invention is constructed separately from the distribution system componentsr with which it is associated to afford loadbreak ability to the system at desired locations without disturbing or replacing the existing components. This separate loadbreak device is easily installed, removed or replaced to afford flexibility and permit ready repair when repeated use causes wear of the consumable arc-extinguishing parts.
The arc-extinguishing mechanism of this loadbreak device is latched in an inoperative position while the contactors are fully engaged to prevent the exertion of any substantial force tending to separate the contactors and upon separation of the contactors the arc-extinguishing mechanism is accelerated by a biasing means such that the velocity oi the interrupter in operation is independent of the speed at which the associated connector is operated.
It is an object of this invention to provide a loadbreak device that may be selectively applied to a system to give loadbreak ability where required.
lt is a further object of this invention to provide a loadbreak device that may be installed in the system without disturbing the existing cable terminations.
It is a further object of this invention to provide a separate loadbreak mechanism with the arc extinguishing consumable parts therein which may be replaced independently of the other associated component parts of the system.
It is also an object of this invention to eliminate the manufacture, inventory and use ot' a plurality of styles of connectors to selectively provide loadbreak capability to distribution systems.
It is also an obje-ct of this invention to provide a loadbreak device where the interrupter speed is independent of the speed at which the connector is operated.
These and other objects and advantages of the invention will become apparent from the following description when taken in connection with the accompanied drawings, wherein:
FIGURE l is a sectional elevation view of the loadbreak mechanism of this invention shown with an associated equipment bushing and cable termination partially in -section and partially broken away; and,
FIGURE 2 is a partial elevation view partly broken away and partly in section of the loadbreak mechanism of FIGURE l with the cable termination removed from contact therewith.
Referring to the drawings, the apparatus bushing 16 is shown projecting through an aperture in an electrical housing 12 which is sealed by a gasket 13 disposed between the bushing flange 14 and the exterior wall surface of the housing. rl`he bushing is maintained in position by a hold-down plate 16 which bear-s against the upper surface of the bushing ange 14 and is Secured to apparatus housing 13 by means not shown, The bushing 10 is formed of a body of electrically insulating material through which passes a central conductive member which is tubular at its upper end to receive the Vterminal portion of a cooperating coupling member. Bushing 10 also presents a truste-conical parting surface 19 which is received by a cooperating frusto-conical recess to afford a suh- States Patent O "ice stantially uninterrupted radially outwardly extending electrical insulation about the central conductive portions.
A distribution cable 26 is provided with a termination 2S which has a closed loop 29 projecting from the outer peripheral surface to provide for hook stick operation ot' the termination. The cable termination 28 is provided with a housing 3G of conductive material and an inner shield member 32 to which the cable conductor is electrically connected. Intermediate the housing 30 and the inner shield 32 is cast or otherwise formed a continuous wall 34 of insulating material. A truste-conical recess extends into the termination through the insulating wall 34 and terminates inwardly within the shield member 32. Projecting axially within the recess 35 and forming an integral part of the shield member 32 is a cylindrical terminal contactor which has a diametrical saw cut 41 extending axially from the distal end thereof.
In the coupled condition with the ltermination 2S connected to the bushing 10, the truste-conical projection of the bushing is received in the frusto-conical recess 35 of the termination with the terminal 40 disposed within the tubular end of conductive member 17 and the distal end of the bushing frusto-conical projection terminating within the conductive shield 32.
As shown in the drawings, there is mounted intermediate the cable termination 28 and the equipment bushing 1t? an auxiliary fitting 44 which includes the loadbreak mechanism of the present invention and is equipped with cooperating frusto-conical coupling portions to enable coupling to both the bushing and the termination. The litting 44 has a conductive housing 46 about the periphery thereof and presents within the electrical insulating material 34 a downwardly opening rusto-conical recess which terminates at the upper end in a shield member 47 and receives the bushing frusto-conical proje-ction therein. The bushing projection terminates within the shield member which also has extending therefrom a bayonet contacter 49 that electrically connects with the inner conductive member 17 of the bushing 10. At the upper end of the loadbreak device is a frusto-conical projection which extends into and is received by the rustoconical recess 35 of the cable termination 28 and presents a cylindrical axial opening or passageway 51 in which the cable termination terminal conductor 40 is received. The frusto-conical parting surface between the inner conductive portions of cable termination 28 and loadbreak fitting 44 and the outer conductive grounded housings 3) and 46 respectively affords an extended creepage path between these conductive portions of diftering electrical potential.
At the upper terminal end of the loadbreak fitting 44 is a cylindrical member 55 formed of arc-quenching insulating material with the bore therethrough defining a portion of the passageway 51 in which the termination bayonet conductor is received. Extending axially below the cylinder 55 is a generally cylindrical conductor member 56 formed of highly conductive material that has a lower portion in intimate electrical contact with the shield member 47 and an upper bore 57 which forms a part of passageway 51 and presents a surface that provides the electrical contact between the load-break itting 44 and cable termination terminal 40 in the coupled condition. The bore within the conductor has an enlarged intermediate portion 5S extending from shoulder 59 and a further enlarged lower portion 61 extending from the shoulder 62. A follower 64 fabricated of arc-extinguishing material has an upper cylindrical portion 65 Slidably received in the upper bore 57 of conductor 56 and a lower cylindrical portion 66 slidably received in the bore 58 of the conductor to permit axial movement of the follower member to an uppermost position where the shoulder 68 of follower 64 abuts the shoulder 59 of conductor 56. The follower drive spring 70 has one end in abutting relation with the lower axial end of follower member 64 to provide an upward biasing of the follower member. An axial bore extends through the follower member with an upper cylindrical surface 72 and a lower enlarged cylindrical surface 73 separated by a shoulder 74. Disposed in the bore of the follower member is a plastic trigger pin 77 which has an upper portion 78 journaled within the follower upper cylindrical surface 72 and a lower portion 79 of greater diameter journaled for sliding movement within the lower enlarged cylindrical surface 73 of follower 64. The trigger pin 77 has a lower projection 80 about which is carried a compression spring 82 with an upper cylindrical portion constrictively engaging projection 8G and a lower volute portion extending downwardly from the trigger pin. The spring 82 is adapted to be compressed against the wall surface 84 of shield member 47 when follower 64 and trigger pin 77 are depressed to the position shown in FIGURE 1. In the lower portion of follower 64 is a radial bore 86 extending from the enlarged bore 73 of the follower and terminating in the peripheral surface of the follower lower cylindrical portion 66. Disposed in radial bore 86 and carried by follower 64 is a followerretaining ball 88 which has a diameter greater than the aX- ial length of radial bore 86. As seen in FIGURE 2, it will also be noted that the follower shoulder 74 terminates upward travel of trigger pin 77 before the lower projection 8f) of the trigger pin passes axially beyond radial bore 86 to thereby retain the follower-retaining ball 88 captive within the radial bore during all conditions of operation.
In operation, the loadbreak device is connected by the terminal 49 to the apparatus bushing 10 and thereafter loadbreak connecting and disconnecting is effected by connection and disconnection of the cable termination 28 to the auxiliary loadbreak fitting 44. When termination 28 is connected to the loadbreak fitting 44, the terminal 40 first engages the axial end of trigger pin 77 and depresses the trigger pin until the shoulder 90 thereof abuts the surface of follower-retaining ball 88 whereupon the trigger pin and follower 64 commence to move downward in unison as a result of the driving connection between the trigger pin and the follower-retaining ball. When the follower-retaining ball 88 is depressed to the location oi the shoulder 62, the ball 88 moves radially outward permitting the peripheral surface of enlarged portion 79 of the trigger pin to pass axially. In this condition, the follower drive spring 70 is compressed between the wall surface 84 of shield 47 and the lower axial end wall of follower 64 and is restrained against exerting an upward movement by the abutting relation between the follower retaining ball 88 and the conductor shoulder 62. The terj minal 40 thereafter depresses trigger pin 77 downward against the biasing force of the trigger pin drive spring 82 until intimate contact is established between the frustoconical projection of loadbreak fitting 44 and the frustoy conical recess 35 of termination 28 at which time terminal 40 is in positive electrical engagement with the contact surface portion 57 of loadbreak fitting conductor 56. In this connected condition, the follower drive spring 70 is inoperative to exert a force upwardly which would tend to induce a disconnection of the terminal 40 of termination 28 from the loadbreak fitting 44.
` When the termination 28 is moved upward to disconnect the terminal 40 from the conductor 56, the trigger pin 77 is urged initially by the trigger pin drive spring 82 causing the trigger pin 77 to intimately follow the lower surface of terminal 40 as the latter is withdrawn from passageway 51 until trigger pin shoulder 90 reaches followerretaining `ball 88. As the terminal 40 is withdrawn further, the follower-retaining ball 88 is released from shoulder 62 releasing follower drive spring 70 to drive follower 64 upward whereupon the follower is moved to a position where the upper portion is journaled within the cylinder 55 of arc-extinguishing material so that any arc which occurs between the termination terminal 40 and the loadbreak fitting conductor 56 is confined and extinguished by arc-extinguishing gas emitted from the material of cylinder 55 and follower 64. The follower-retaining ball 88 is released at approximately the position of final contact between terminal 40 and conductor 56 and since follower 64 is moved axially into concentric relation with the sleeve 55 by follower drive spring 70, the speed of the arc extinguishing cooperation between sleeve 55 and follower 64 is dictated by the action of follower spring 70 and is independent of the speed at which the conductor termination 28 is withdrawn.
It will be readily apparent that the loadbreak mechanism of fitting 44 could be incorporated as an integral part of bushing 10 with the same operating qualities; however, the ease of replacement and insertion into the system would diminish the tiexibility of system design or change and maintenance.
Although but one embodiment has been shown and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.
1. A. loadbreak device for use with a cable termination having a terminal conductor comprising a coupling portion with a passageway adapted to slidably receive said termination terminal conductor; a sleeve portion of arccxtinguishing insulating material surrounding and partially defining said passageway and extending axially from the entrance to said passageway; a tubular conductor member axially spaced from the entrance of said passageway by said sleeve portion and partially defining said passageway; a follower means of insulating material carried by said coupling portion with at least a portion t thereof axially movable within said passageway; biasing means urging said follower means toward the entrance of said passageway; stop means limiting travel of said follower means towards said entrance of said passageway to a first position with a portion of said follower concentrically received within said sleeve whereby said follower means is depressed against said biasing means when said termination terminal conductor is slidably inserted into said passageway into contacting relation with said tubular conductor and is returned by said biasing means to said first position as said termination bayonet conductor is withdrawn from said passageway and means for preventing movement of said follower means to its` first position until said terminal conductor is withdrawn a predetermined distance outwardly of said passageway.
2. The loadbreak device of claim 1 whereinv said coupling portion further includes latchv means for retaining said follower means in said second position when said follower means is depressed by insertion of said terminal conductor into said passageway and latch control means responsive to withdrawal of said termination bayonet conductor for releasing said latch means.
3. The loadbreak device of claim 1 further comprising in combination, a bushing member having a passageway with a terminal member therein adapted to receive said cable terminal conductor, said loadbreak device further having a second coupling portion including a terminal conductor for electrical connection to said tubular conductor and adapted to be received in said bushing passageway in electrical contact with said terminal member, whereby said loadbreak device may be selectively removably connected to said bushing and said cable termination to provide a loadbreak electrical connection therebetween.
4. The loadbreak device of claim 2 wherein said latch means comprises a radially movable latching member carried by said follower means and axially confined with respect to said follower means by wall surfaces formed therein and a latch-retaining shoulder surface formed in the wall forming said passageway which engages said latch member when said follower means is depressed against said biasing means to a second position and said latch member' is moved and retained radially outward by said latch control means.
5. The loadbreak device of claim 4 wherein said latch control means comprises a trigger pin slidably received in an axial bore within said follower means and said trigger pin has one end portion projecting beyond the end of said follower means when said follower means is in said first position, a shoulder which forms a driving connection with said latch member to cause said trigger pin and said follower means to move in unison as said trigger is depressed until said latch member moves radially outwardly to engage said shoulder, and a latch member engaging surface which retains said latch member in said radially outward position in engagement with said latch retaining shoulder as said trigger pin is further depressed.
6. The loadbreak device of claim 2 wherein said latch means comprises a cylindrical radial passageway in said follower means between an axial bore and the peripheral surface thereof, a follower-retaining ball in said radial passageway with the diameter of said ball greater than the length of said radial passageway; a latchretaining shoulder formed in said tubular conductor member; a trigger pin slidably mounted in said follower means axial bore with a portion normally projecting beyond the axial end of said follower means nearest the entrance to said coupling portion passageway; said t1 igger pin having a first cylindrical portion permitting said follower-retaining ball to project into said bore while retaining said ball in said radial passageway; a second cylindrical portion siidable in said bore and engageable with said follower-retaining ball to cause said ball to project beyond tbe periphery of said follower means and a shoulder portion intermediate said first and second cylindrical portions adapted to form a driving connection with said ball when the latter projects into said bore whereby as said terminal conductor is inserted into said passageway said trigger pin shoulder portion engages said follower means retaining ball and said trigger pin and follower member thereafter move in unison until said follower-retaining ball reaches said latch retaining shoulder whereupon said follower means retaining ball moves radially outward to retain said follower means and said trigger thereupon may move independently of said follower means with the biasing means restrained by said follower-retaining ball against the exertion of an axial force against said terminal conductor.
7. A loadbreak device for use with a cable termination having a terminal conductor comprising a coupling portion with a passageway adapted to slidably receive said termination terminal conductor; a sleeve portion of arc-extinguishing insulating material surrounding and partially detining said passageway and extending axially from the entrance to said passageway; a tubular conductor member presenting a cylindrical surface partially delining said passageway, said tubular conductor member surface being axially spaced from the entrance of said passageway by said sleeve portion; a follower assembly, carried by said coupling portion and including the cylindrical member of arc-extinguishing insulating material, slidably received in said passageway; biasing means urging said follower assembly toward the entrance of said passageway; stop means for limiting travel of said follower assembly towards said entrance of said passageway to a first position with a portion of said cylindrical member concent-rically slidably received within said sleeve; latch means carried by said follower assembly and cooperable with said tubular conductor member to retain said cylindrical member in a depressed second position restraining said biasing means, and latch control means for engaging said latch means upon a predetermined insertion of said terminal conductor into said passageway and releasing said latch means as said terminal conductor is withdrawn from said passageway, whereby said bayonet conductor may be positioned in said passageway in electrical contact with said tubular conductor member without a force being exerted against said terminal conductor by said biasing means.
8. The loadbreak device of claim 7 wherein said latch control means releases said latch means upon withdrawal of said terminal conductor prior to termination of electrical contact between said terminal conductor and said tubular conductor member.
9. The loadbreak device of claim 7 further comprising in combination, a bushing member having a passageway with a terminal member therein adapted to receive said cable termination terminal conductor, said loadbreak device further having a second coupling portion including a terminal conductor electrically connected to said tubular conductor and adapted to be received in said bushing passageway in electrical contact with said terminal member whereby said loadbreak device may be selectively removably connected to said bushing and said cable termination to provide a loadbreak electrical connection therebetween.
References Cited UNITED STATES PATENTS RCHARD E. MOORE, Primary Examiner.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,384,861 May 2l 1968 Davis M. Phillips It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:
Column 4, line 55, "termination bayonet" should read terminal Signed and sealed this 28th day of October 1969.
Edward M. Fletcher, Jr.
Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, IR.