US 3614700 A
Description (OCR text may contain errors)
United States Patent  Inventors Lloyd R. Beard;
Delmar E. McNaghten; Charles A. Popeck, all of Centralia, Mo.
 Appl. No. 819,275
 Filed Apr. 25, 1969  Patented Oct. 19, I971  Assignee A.B. Chance Company Centralia, Mo.
 ON-THE-LINE DISTRIBUTION CUTOUT SWITCH 6 Claims, 10 Drawing Figs.
 U.S.Cl 337/203, 200/48, 337/171  Int. Cl ..H0lh 31/00, l-lOlh 31/12, HOlh 31/34  Field of Search 174/40;
 References Cited UNITED STATES PATENTS 3,510,611 5/1970 Bridges 200/48 3,374,329 3/1968 Bronikowski 337/203 X Primary ExaminerBernard A. Gilheany Assistant ExaminerDewitt M. Morgan At!0rne vSchmidt, Johnson, Hovey & Williams ABSTRACT: A distribution cutout which is both electrically connected to a current-carrying line and mechanically connected thereto for support by the line without breaking the latter. The cutout is particularly adapted for use in overhead distribution circuitry where crossarms are not available as a support. The switch arm of the cutout comprises a tubular fuse holder from which a fuse link therewithin is ejected when a fault is encountered, a guard being provided which blocks the ejecting link to prevent the establishment of an are between such link and the line. Both the head of the link and the frangible disc used to seal the fuse holder are captured by a vented retainer.
ON-THE-LINE DISTRIBUTION CUTOUT SWITCH This invention relates to improvements in cutouts employed in overhead distribution circuitry to tap into the main line.
With the present demand for improvement in the appearance of overhead distribution circuitry utilized for electric power transmission, public utilities have become increasingly aware of the need for switching and other transmission apparatus which is aesthetically pleasing as well as functional. As a major step in improving the appearance of overhead circuitry, the use of armless construction (line poles without the usual crossarms) has become increasingly widespread. This creates a problem with respect to switching apparatus, for example, in that the traditional wooden crossarm is no longer available as a support or mount for the apparatus.
Although in distribution circuitry, in-line" distribution cutouts which do not require crossarms for mounting have had limited use for a number of years, the main line must be cut in order to make the necessary connections to the cutout units. Crossarm mounted units make it possible to leave the line intact and have enjoyed widespread use, but present a cluttered appearance to the eye due to the crossarms and other hardware required in a circuit construction of this type.
It is, therefore, the primary object of this invention to provide switching apparatus, such as a distribution cutout or similar structure, which may be mounted on the line" without cutting or breaking the line and without the need for support by a crossarm.
As a corollary to the foregoing object, it is an important aim of the present invention to provide apparatus as aforesaid which is pleasing from the aesthetic standpoint and hence suitable for overhead circuitry applications.
In furtherance of the foregoing objects, it is also an important aim of the invention to provide apparatus as aforesaid which is mechanically connected to the line for support thereby and electrically connected thereto by common connector means, in order to render the apparatus entirely compatible with armless overhead circuitry construction.
Another important object of this invention is to provide apparatus as aforesaid which may be installed on an energized line with hot line tools and without elaborate procedures.
Still another object of the invention with respect to distribution cutouts, is to provide a means of preventing accidental arching between the line and the fuse link of the cutout when the link interrupts and is ejected from the fuse holder.
Additionally, it is an important object of the invention to provide a means of capturing both the head of the fuse link of a cutout and the frangible disc utilized to seal the fuse holder, upon ejection of the head and fracture of the disc at the time of interruption of the fuse link, yet while simultaneously providing the necessary venting of the fuse holder. Retaining the disc as well as the head is particularly important in cutouts of the present invention having a high interrupting capacity rating since, besides the hazard to adjacent property or persons nearby, the fuse holder is suspended directly beneath a line conductor such that, if the disc or the head were permitted to eject, the trajectory of the ejected projectile could intersect the line conductor and cause damage thereto.
Specifically, it is an important aim of the invention to provide a retainer for the fuse link head and the frangible disc which has a vented chamber configured to capture the disc and the head while permitting relatively unrestricted flow of expanding gases through the vent or vents thereof.
In the drawings:
FIG. I is a side elevational view of the distribution cutout showing the same attached to a current-carrying line;
FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;
FIG. 3 is a sectional view taken along line 3-3 of FIG. 1;
FIG. 4 is a fragmentary, plan view of the guard which blocks the ejected fuse link;
FIG. 5 is a fragmentary, sectional view taken along line 5-5 of FIG. 1;
FIG. 6 is an enlarged, longitudinal sectional view of one embodiment of a retainer, shown mounted on the end of the fuse holder;
FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 6;
FIG. 8 is an enlarged, longitudinal sectional view of a second embodiment of a retainer, shown mounted on the end of the fuse holder;
FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 8; and
FIG. 10 is an enlarged, longitudinal sectional view of a third embodiment of a retainer, shown mounted on the end of the fuse holder.
Referring to FIGS. 1-5, a distribution cutout broadly denoted 20 includes a base in the form of an elongated, horizontal angle member 22, the ends thereof being provided with extensions 24 which mount a pair of hot line clamps 26. Each clamp 26 has an upper jaw 28 bolted to the respective extension 24, and a movable lower jaw 30 which is shifted toward and away from the upper jaw 28 by rotating an eye screw 32 adapted to receive a suitable hot line installation tool. The two clamps 26 serve as connectors to both mechanically attach the base member 22 to a current-carrying line 34 and establish electrical connections with the line 34 at both ends of member 22.
An insulator 36 is secured to the bottom flange of member 22 and depends therefrom, a terminal structure 38 being mounted on the lower end of insulator 36. A switching device broadly denoted 40 is carried by the terminal structure 38 and a mounting leg 42 depending from base member 22 which is spaced from the insulator 36 longitudinally of member 22. The switching device 40 has a fixed contact 44 and a movable switch arm 46 which is shiftable toward and away from the contact 44 to establish or interrupt electrical continuity between the terminal structure 38 and the line 34, as will be subsequently described.
The switch arm 46 includes a tubular, nonconductive fuse holder 48 having an open, lower end 50. The upper portion of the fuse holder 48 is provided with a ferrule 52 which carries a forked operating arm 54 pivotally mounted thereon by a pin 56. The operating arm 54 is biased in a counterclockwise direction (as viewed in FIG. 1) about the pin 56 by a spring (not shown) toward the position illustrated, movement of the arm 54 in a clockwise direction being effected by a lineman utilizing a switch stick hooked through the operating ring 58.
The ferrule 52 has a projecting hook 60 which presents the movable contact of the switching device 40, the hook 60 engaging a catch 62 extending from within an upper sleet hood 64 integral with the lower end of the mounting leg 42. The fixed contact 44 is also housed within the hood 64 and extends therefrom into engagement with the hook contact 60, as is clear in FIG. 1. An expendable cap 66 (FIG. 2) is shown threaded on the upper end of the fuse holder 48 and is contained within a gas shield 68.
A support assembly 70 is secured to the lower end of the fuse holder 48 and is provided with a pair of opposed gudgeons 72 which are received by a pair of stationary bearing elements 74 integral with a lower sleet hood 76 that, in turn, is integrally formed with the terminal structure 38. The assembly 70 further includes a rotary contact member 78 and a springloaded link ejector 80, the latter being shown in engagement with the leader 82 of a first link 84 to be discussed subsequently with reference to FIGS. 6-10.
A full description and illustration of the construction and operation of the cutout switching device 40 appears in Bridges et al., US. Pat. No. 3,026,391, granted Mar. 20, 1962, and entitled Fuse Cutout Operating Tool, said patent being incorporated herein by reference as may be necessary for a complete understanding of the operation of switch devices of this type. Therefore, the remainder of the specification will be directed primarily to the improvements of the present invention over distribution cutouts of the general type shown and described in the aforesaid patent.
The terminal structure 38 is provided with a pair of opposed, laterally projecting lugs 86 (FIG. 5), a laterally projecting stirrup 88 being securely bolted to one of the lugs 86 in order to present a terminal to which a conductor 90 may be connected. Such connection is effected by a hot line clamp 92 which is similar in configuration to the hot line clamps 26 previously described in detail. Note that the stationary upper jaw 94 of the clamp 92 fits over the stirrup 88, the movable lower jaw 96 thereof being in engagement with the under surface of the stirrup 88. An eye screw 98 provides a means of attaching the clamp 92 to the stirrup 88 with a hot line tool. A guard in the form of a mesh 100 held by a wire form 102, is mounted on the lower sleet hood 76 and extends downwardly at an inclination to dispose the mesh 100 adjacent the open lower end 50 of the fuse holder 48. This positions the mesh 100 in the ejection path of the fuse leader 82 to block the latter and thereby prevent further upward movement thereof upon ejection.
Referring to FIGS. 6 and 7, a retainer 104 is illustrated which may be added to the upper end of the fuse holder 48 upon removal of the gas shield 68. The retainer 104 includes a housing 106, the upper or outer portion thereof being of generally hexagonal, frusto-pyramidal configuration and having six vents 108 therein communicating with chamber 120 defined by the housing 106. The upper end of the fuse link 84 is shown in detail in FIG. 6, where it may be seen that the link 84 is provided with a buttonhead 126 which is seated against the upper end of the fuse holder 48, thereby closing the upper end of the fuse holder. The expendable cap 66 is threaded onto such end and has an end wall 128 in overlying engagement with the buttonhead 126. The end wall 128 is a frangible, pressure-responsive element in the nature of a disc which seals the upper end of the fuse holder 48 to prevent the entry of moisture and foreign particles and to improve the interrupting operation of the fuse link 84 under low fault conditions.
The base portion of the retainer housing 106 has a circular opening 130 therein registering with the frangible element 128 and communicating with the internal chamber 120 of housing 106. A cup-shaped nut 132 fits under the cap 66 around the fuse holder 48 by virtue of an opening 134 therein of lesser diameter than the cap 66 but greater than the diameter of the fuse holder 48. The cylindrical sidewall of the nut 132 is internally threaded, and the base of the housing 106 is provided with an integral, externally threaded skirt 136 which fits over the cap 66 and within the nut 132 in mating engagement with the threads thereof.
FIGS. 8 and 9 illustrate a second embodiment of an add-on retainer designated 138. As in the first embodiment just described, the retainer 138 includes a hollow housing 140 defining a chamber 142 therewithin. A single vent 144 in the outer end or top of the housing 140 communicates with the chamber 142, three integral, radial ribs 146 being centrally disposed within the chamber 142 and integrally formed with the housing 140.
The expendable cap 66a of the embodiment of FIGS. 8 and 9 is modified by the addition of external threads to its cylindrical sidewall. The retainer housing 140 is generally cylindrical in configuration and has an internally threaded collar portion 148 which mates with the external threads on the cap 660. A circular opening 150 registers with the frangible end wall 128a of cap 662 and communicates with the chamber 142. The relationship of the cap 660 and its end wall or frangible disc element 128a to the buttonhead 126 of the fuse link 84 is identical to that as described above with respect to the embodiment of FIGS. 6 and 7.
A third retainer embodiment is shown in FIG. and designated 152. In this embodiment, the retainer 152 is functionally combined with the expendable cap 66 or 66a described above with respect to the embodiments of FIGS, 6-9. Retainer 152 has a generally cylindrical, unitary housing 154 defining a chamber 156 therewithin communicated to atmosphere by a vent 158 in the outer end or top of the housing 154. As in the embodiment of FIGS. 8 and 9, three integral ribs 160 are centrally disposed within the chamber 156, and the end of the housing 154 proximal to the fuse holder 48 comprises an internally threaded collar portion 162. However,
the collar portion 162 is threaded directly onto the end of the fuse holder 48, a frangible disc element 164 being mounted inside the housing 154 between the collar portion 162 and the internal chamber 156. A circular opening 166 communicates the chamber 156 with one side of the disc element 164, the other side thereof being in overlying engagement with the buttonhead 126 of the fuse link 84 to seal the fuse holder at its upper end.
In the utilization of the present invention, the cutout 20 may be installed on the line 34 while the latter is energized, since the two hot line clamps 26 permit the use of hot line tools. The installation is quite simple since it is only necessary that the clamps 26 be opened, their upper jaws 28 hooked over the line 34, and then closed into solid electrical and mechanical contact with the line 34. Therefore, the switching device 40 of the cutout 20 is suspended directly beneath the line 34 with both mechanical and electrical connections to the line being provided by the two clamps 26. It is important to note that the base member 22 and its extensions 24 are mounted in substantial parallelism with the line 34 to provide an aesthetically pleasing appearance and, additionally, a parallel current path between the clamps 26 through the base member 22 is provided to further reduce the risk of an improper electrical connection with the line 34.
It should also be noted that there are no external forces on the insulator 36 to place the same in tension, other than the weight of the terminal structure 38 and the switching device 40 and associated components.
In tapping into the line 34, the tap connection to the cutout 20 (and tap connections to the additional cutouts of multiphase transmission circuitry) is made with the hot line clamp 92 to which the tap conductor is connected. The projecting stirrup 88 of the terminal structure 38 facilitates attachment of the clamp 92 for hot line work due to the clearance provided beneath the stirrup 88 for the installation tool.
The operation of the switching device 40 upon interruption of the fuse link 84 is described in the aforesaid U.S. Pat. No. 3,026,391, and thus will not be described in detail in this specification. It should be noted, however, that the opposed gudgeons 72 are seated in bearing elements 74 with the end of the fuse leader 82 secured to contact member 78 and with the spring-loaded ejector 80 in engagement with the leader 82. While tension remains on the fuse leader 82, the hook contact 60 is held in engagement with the catch 62 to maintain circuit continuity between the line 34 and the conductor 90. Interruption of the cutout occurs when the fusible, current-responsive segment of the fuse link 84 melts, whereupon the hook contact 60 disengages from catch 62 since the fuse link 84 is broken, resulting in the release of the spring pressure of ejector 80 which lowers the fuse holder 48 to a position where the hook contact 60 clears the catch 62. The switch arm 46 then rotates about the axes of gudgeons 72 until it hangs freely from the bearing elements 74. This positively breaks the circuit through the fuse holder 48 to prevent the possibility of restriking internally of the holder. The fuse link is subsequently replaced and the switch arm 46 returned to the position illustrated to reclose the circuit between the line 34 and the conductor 90.
At the time of ejection of the fuse leader 82 and attendant swinging of the switch arm 46 about the axes of the gudgeons 72, the fuse leader 82 is whipped in a clockwise direction as viewed in FIG. 1 by the blast pressure of the expanding gases produced as the fuse link interrupts and incidentally by the ejector 80. In order to positively prevent the free end of the leader 82 from swinging into contact or close proximity to the line 34 and causing an arc to strike, the guard mesh is positioned in the ejection path of the leader 82 to block its upward movement. Thus, the leader 82 is deflected downwardly to positively prevent an arcing condition.
Also at the time when current through the current-responsive segment of the fuse link 84 exceeds the rated value of the link, the current-responsive segment volatilizes, thereby serving the link, and an arc is established in the bore of the fuse holder 48. Rapid expansion of the gases thus produced occurs throughout the fuse holder 48 with attendant buildup of high pressures, resulting in venting at the lower end 50 thereof and pressurization of the upper portion of the fuse holder 48 where the fuse holder is closed by the buttonhead 126 of the fuse link 84 and sealed by the expendable cap 66 or 660 (FIGS. 2 and 6-9). Referring to FIG. 2, the frangible disc element of the cap 66 is selected to rupture at a preselected pressure to prevent destruction of the fuse holder 48, the gases thus also being vented to atmosphere at the upper end of the fuse holder by the rupture of the disc element and attendant ejection of the fuse link head.
However, for cutouts having high interrupting capacity ratings, the forces produced by the expanding gases in the fuse holder and the size of the fuse link head cause the head to be ejected as a projectile of high energy constituting a hazard to surrounding persons or property when the fuse holder is positioned in the horizontal or near horizontal position. Furthermore, the ruptured disc element is also ejected under high force and may also constitute a hazard. This is particularly acute for an additional reason in the present invention where the fuse holder 48 is disposed directly beneath the line 34, since the trajectories of the ejected disc element and the head may intersect the line 34 and thereby cause the latter to be damaged by the ejected projectiles.
in the retainer embodiment of FIGS. 6 and 7, ejection of both the disc element or end wall 128 of the cap 66 and the buttonhead 126 of the fuse link 84 is prevented by the vented retainer housing 106. When the disc element 128 ruptures, it is ejected into the chamber 120 through the opening 130 but is trapped within the chamber at least until its energy is dissipated since the vents 108 are triangularly shaped, narrow toward the outer or upper end of the housing 106, and located in laterally or generally radially facing relationship to the longitudinal axis of the fuse holder 48. The same is true with respect to the buttonhead 126 which is also ejected into the chamber 120 through the opening 130. However, passage of the expanding gases within the fuse holder 48 is not substantially impeded due to the relatively large volume of the chamber 120 and the presence of the six vents 108 which effectively surround the chamber and define a number of possible paths for flow of the gases to atmosphere.
in the embodiment of FIGS. 8 and 9, the chamber 142 is also aligned with the longitudinal axis of the bore of the fuse holder 48 as in the embodiment of FIGS. 6 and 7, but venting of the chamber is accomplished by the single vent 144 which is axially aligned with the axis of the fuse holder. The ribs 146 block the disc element 128a upon rupture and ejection thereof into the chamber 142, and also block the buttonhead 126, both of which would otherwise pass on through the chamber 142 and out through the vent 144. However, although the ruptured element 128a and the buttonhead 126 are held within the chamber 142, the open sectors between adjacent ribs 146 permit relatively unobstructed passage of the expanding gases and thus adequate venting of the fuse holder is accomplished.
in the embodiment of FIG. 10, the combination capturing or trapping and venting action is the same as in the embodiments of FIGS. 8 and 9. However, the housing 154 supports the frangible disc element 164 and thus a separate cap is not required.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:
1. in a switching device:
a fixed contact;
a removable switch arm engageable with said contact and including a tubular fuse holder having an open end;
a fuse link within the fuse holder provided with a head closing said end;
frangible element adjacent said end disposed in pressure sealing relationship thereto; and
a retainer on said end having a chamber communicating with said element for capturing the latter and the head upon interruption of the link and attendant generation of expanding gases,
said retainer including a housing defining said chamber therewithin and provided with an opening therein between said element and said chamber registering with the element and communicating with the chamber,
said element, said opening and said chamber being aligned with the longitudinal axis of said fuse holder whereby, upon said interruption of the link, the element and the head are ejected into said chamber through said opening in a longitudinal direction outwardly from said end of the fuse holder,
said housing having passage means therein communicating with said chamber to vent the latter and provide a path for flow of said gases to atmosphere from said chamber through said housing extending generally in said direction and devoid of significant obstructions to free, unimpeded flow.
2. 1n the device as claimed in claim 1,
said housing having an end remote from said end of the fuse holder,
said remote end of the housing having a vent therein aligned with said axis,
said retainer further including rib structure in said chamber for preventing ejection of the element and the head through said vent.
3. in the device as claimed in claim 1,
there being a cap on said end having an end wall presenting said element; and
a nut on said end engaging said cap with the latter disposed between the nut and the retainer,
said retainer having a threaded base portion telescoped over said cap in mating engagement with said nut to thereby secure the retainer to the cap.
4. in the device as claimed in claim 1,
there being a cap on said end having an end wall presenting said element,
said cap having a generally cylindrical sidewall substantially coaxial with said fuse holder and provided with external threads,
said housing being provided with internal threads engaging said external threads to secure the retainer to the cap.
5. In the device as claimed in claim 1,
said housing being of unitary, one-piece construction and receiving said end,
said housing having means mounting said element therein in said pressure sealing relationship to said end.
6. In the device as claimed in claim 1,
said housing having an outer end remote from said end of the fuse holder,
a portion of said housing being tapered toward said outer end to progressively reduce the cross-sectional area of said chamber as said outer end is approached,
said portion of the housing having a plurality of spaced vents therein presenting said passage means and disposed in surrounding relationship to said chamber.