US3668351A

US3668351A - Sectionalizing and protective apparatus for single house transformer

Info

Publication number: US3668351A
Application number: US846187A
Authority: US
Inventors: Carl J Walbrun; Kenneth Earl Hanke
Original assignee: Kearney National Inc
Current assignee: Kearney National Inc
Priority date: 1969-07-30
Filing date: 1969-07-30
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06

Abstract

Apparatus for controlling and protecting an electrical power distribution system from failure occurring in or between single dwelling transformers whose primary windings are energized from a sectionalizable loop. The apparatus includes three disconnect switches, one set of contacts in each being permanently connected in electrical series and the outermost ones of the series have their opposite contacts impermanently connected to different sections of the sectionalizable loop, while the intermediate one of the series has its opposite contacts removably connected to one end of a fuse, the opposite end of which connects with the primary of said transformer, whereby the transformer may be isolated without interrupting the continuity of the loop circuit, or a faulty section of the loop between different single dwelling transformers may be isolated and repaired or replaced without deenergizing any transformer energized from the loop.

Description

[151 3,668,351 June 6, 1972 United States Patent Walbrun et al.

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[22] Filed:

Kearney-National Inc., St. Louis, Mo. July 30, 1969 [2l] Appl. No.: 846,187

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FGE

FAINTEB-Jun 61912 SHEET 2 0F 5 FIGQB FIGA . supply circuit (commonly called a challenges other URD designs,

, 1 siscTioNALlziNG AND PROTECTIVE APPARATUS Fon SINGLE iioUsE TRANsroRMER This invention relates generally to electric power distribuends of which are maintained at the same potential difference Y (distribution voltage) from ground, anda number of single dwelling transformers have their primaries energized by tapping into s aid single-phase lateral somewhere between the ends of the lateral. Such a distribution circuit, if provided with appropriate switching devices at or near the individual transformers, can be sectionalized".so that when a fault occurs at a certain locus along the single-phase lateral, that section of the lateral may be isolated, deenergized and repaired, without interrupting the energization of all of the transformers supplied by that lateral. While said patent discloses a number of different circuit arrangements for so sectionalizing such a loop") that: l) an individual transformer in the system'can be isolated without deenergizing any other; or (2) the increments of the loop intervening two transformers can be deenergized without creating an outage at either of those two transformers; the control system disclosed by said patent for accomplishment of (2) does not permit (l) to be accomplished without interrupting the continuity of the loop. Y Accordingly, it is one object of the present invention to provide for a sectionalizable distribution system of the kind which permits increments of the loop intervening two transformers to be deenergized, and which permits individual transformers to be isolated, with means whereby the latter can be accomplished without interrupting the continuity ofthe loop.

On` the other hand, the more common sectionalizable system is represented by that shown and describedA in the article by-A.G. Dahl, entitled Transformer per house (URT) which appeared in the Sept. 5, 1966, issue of Electrical World. In that system, each section of underground conductor between successive transformer stations is terminated in a separable male-female plug-in type connector, at leastv the movable half of whichis `integrated with the distribution cable, and is manipulable to serve the dual purpose of a load break-and-make. At each transformer, there are two such male-female plug-in connectors, one associated with the underground section which extends to the right, and the other associated withthe underground section whichextends to the left ofthe given transformer station. Among the objections to this arrangement are: that the movable half of such connectors being restrained by the inherent stiffness of the cable which must bend during manual circuitclosing, as well as during manual circuit-making"operations cannot consistently, even by experts, be manipulated with the instantaneity requisite to eliminate the hazard of drawing an exposed arc of dangerous proportions during the process of opening or closing the circuit.

Accordingly, another object of the invention is to provide an arrangement of control and protective devices for the aforesaid purpose which is substantially free of the haz-ards just mentioned, and is not only safe to be manipulated by those skilled in the art, but much less likely tobe hazardous when manipulated by those unskilled in the art than were the male-female plug-in connector type of devices.

These and other objectives are accomplished in accordance with the present invention by the provision, at each individual residence or building, of an electric power service center, including an encased cluster of modular control and protective devices, and a transformer. Different ones of the control devices are so connected at one pole to the termini of dierent sections of asectionalizable loop; and permanently connected at their other pole to each other with an intervening tap through another control device and a series connected protec- Y tematively,

preferable to provide the permanent electrical connection among the one set of contacts in all three disconnect switches. Such electrical connection is termed permanent for the reason that it can only be broken by dismantling the cluster an operation which can be, and preferably is, such as to require some destruction or at least mutilation of some parts.

'The individual modules for the three disconnect switches can be, and preferably are, identical, and include electrically conductive parts, all but one of which is confined within a capsule of insulating material, which capsule preferablycontains a cast-in set of complemental semi-capsular casts of moldable insulating material confining an assembly of stationary contacts and arc-suppressing instrumentalities. v

The protective device, also included within the aforesaid cluster, is of comparable construction, but necessarily different in detail. lt, too, has all but one of its electrically conductive parts confined in an insulating capsule. The protective instrumentality is preferably a fuse releasably mounted at one end upon an insulating handle, and adapted to be inserted and withdrawn in bayonet-scabbard relationship relative to the protective device capsule, so that the end of the fuse connected with the insulating handle makesconductive engagement with one set of contacts within the module, and the end of the fuse remote from the handle makes electrical contact with another set of contacts within the module, but spaced substantially a fuse length from the first set.

v While the insulating capsules of the disconnect switch modules differ in detail from the insulating capsules of the protective device modules, the complemental semi-capsular casts within the disconnect switch capsules are i enantiomorphously related so that a given semi-capsular cast constitutes half the internal chamber for containing the electrically conductive parts which will be subject to arcing; and said internal chamber is itself preferably the core about which the external insulating capsule is molded. v

The invention contemplates that the semi-capsular casts forming said internal chamber be pre-molded with recesses, protub'erances, and other internal configurations which substantially conform to parts of, and hence position, the conductive parts of each module, as well as, when desired,- non-conductive parts such as arc-snuffing devices and their accessories. i y

Once the conductive parts of a given device are assembled in one semi-capsular cast with one set of contacts near one end, and another set of contacts near the other end of the cast, the companion semi-capsular cast may be applied to complete the internal chamber, and the exterior insulating capsule then cast or molded about the internal chamber and contents. Al-

the exterior capsules can be pre-cast in halves, the halves assembled about the internal chamber (with contents) and permanently connected as by mutual solvent, or thermal sealing at the interfaces of the halves to complete the module. Then the complete modules are assembled into the final cluster with the electrically conductive parts at one end of each disconnect switch module all connected together in electrical series and held together by sealing the insulating capsules of the three modules together. Alternatively, all of the respective internal chambers or otherv aforesaid series connected set. On two of the three disconnect switch modules, the exposed electrically conductive part is intended to be connected, by any suitable permanent or impermanent means, with the terminal of one section of the loop circuit. The third of the disconnect switch modules has its exposed electrically conductive part connected to one set of contacts within the protective device module, while the other set of contacts within the protective device module is exposed for permanent or impermanent connection with the primary of the transformer` The protective device, or fuse module, is preferably connected to one of the disconnect switch modules (preferably the middle one) in such manner that the capsule of oneis sealed with the capsule of the other, thereby making the lastmentioned electrical connection of permanent nature.

Preferably, the spaced contacts in all four modules are relatively stationary, that is to say,that they are fixed relative to their respective capsules, save only for resiliency of the parts intended to removably receive a conductive member for selectively bridging the spaced contacts in any one module.

, An illustrative embodiment of the invention, as well as some alternatives for parts thereof, is shown in the accompanying drawings, in which: .Y

FIG. l is a circuit diagramdepicting the type of system to l which the present' invention applies, and diagrammatically illustratin'gthe positions in the circuits where the components of our electric powerv service center are located;

FIG. 2 is a perspective view, with one end cover substantially broken away to reveal the relationship of some parts therewithin, of the enclosure for a service center embodying the invention; v

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2, but showing the cover (which was broken away in FIG. 2) in place;

FIG. 4 is a perspective view of the cluster of control and protective modules embodied in the center shown in FIGS. 2 and 3; i

v FIG. S is atop plan view of the cluster of modules shown in FIG. 4;

FIG. 6 is a view in side elevation taken along the plane designated 6 6 in FIG. 5,'part being broken away to reveal the electrical connection between the center module of FIG. andthe protective device module therebelow;

FIG. 7 is a longitudinal sectional View taken along line 7 7 of FIG. l2, and showing the relationship of electrically conductive and insulating parts within aA disconnect switch module; v

FIG. 8 is a sectional view taken along line 8-8 of FIG. 12, and showing the relationship of stationary conductive and insulating parts within the protective device module;

' FIG. 9 is a view in side elevation of a removable contact member for use-in connection with the disconnect switch modules; l

FIG. l0 is a view in side elevation of a removable fuse and handle for use in connection with the protective device module shown in FIG. 8;

FIG ll is a sectional view-corresponding to the sectional view in- FIG. 8, but depicting an alternative construction for the protective device module;

FIG. l2 is an operating end view of the cluster of control and protective devices as seen through the open end of the enclosure shown in FIG. 2, with parts broken away to reveal the location of instrumentalities shown in dotted lines in FIG. 2;

FIG. 13 is a perspective view of the insulating handle portion ofthe deviceshownin FIG. as seen from the-fuse gripping end thereof;

FIG. 14 is a perspective view of the stationary contact set embodied in the disconnect switch modules at the end thereof` where those contacts are permanently connected together among the three disconnect switch modules;

FIG. 15 is a perspective view of the stationary contact set embodied in the disconnect switch modules at the opposite end thereof from the location ofthe set shown in FIG. 14;

4 FIG. 16 is a perspective view of one o f the arc-extinguishing clappers shown in FIG. 7; 1 l

FIG. 17 is a perspective view of an arc-extinguishing halfliner for the insulating capsule shown in FIG. 7; and

FIG. 18 is a perspective view of the fuse keeper shown in FIGS. 2 andvl2.

In the distribution system shown in FIG. 1, the generator 1 produces three-phase voltage which energizes the primaries 2 of a three-phase transformer, whose secondary 3 is at a higher voltage for transmission. v

At a chosen locality, the transmission voltage energizes the primary 4 of a three-phase transformer or bank of transformers, whose secondary 5 is a Y-connected, grounded neutral, producing the distribution voltage of, say, 7,200 volts between ground and each of

conductors

6, 7 and 8, respectively. The

several distribution conductors

6, 7 and 8, which may be either overhead lines or underground lines, extend to different localities in the proximity of each other, line 8 serving a sectionalizable loop 9, line 7 sectionalizable a sectionalizable loop 10, and line 6 serving a sectionalizalbe underground loop ll'shown on larger scale than the loops9 and 10 in order to illustrate the detail of the circuit control devices embodied therein in accordance with the present invention. It will be observed that the loop 1 1- connects with distribution conductor 6 at two

points

12 and 13. Hence, both ends of theA loop l lare at y substantially the same potential difference from ground. As "shown, the underground loop 1l is sectionalizable into five sections located, respectively, between fused switch 14 and switch l5, between switch 16 and switch 17, between switch 18 and switch 19, between switch 20 and switch 21. Normally the loop operates with a switch near the mid-point in the loop (e.g., 18) in open circuit position, but energization of all instrumentalities connected with the loop is continued by supplying those on one side of the open switch from connection l2, and those on the other side of the open switch from point 13. Hence, if a ditch-digger mutilates the underground cable between switches 16 and 17, for example, those switches may .be opened to isolate the mutilated section of cable, and normally-open switch 18 closed, without requiring outage of any one of

transformers

22, 23, 24 or 25,.while the'mutilated cable is being repaired. In the arrangements diagrammatically illustrated in FIG. 1,

transformers

22, 23, and 24 are each a part of a service center constructed in accordance with the present invention,` but transformer 25 is different, as willy be later described. v

The secondary of each of the transformers, however, is shown as being designed to supply either or both of l20 volt or 240 volt service to the adjacent dwelling.

The service center, constructed in accordance with lthe present invention as'seen in FIGS. 2 and 3, includes an enclosurer26 of sheet metal, or other appropriate weather-resisting material, having two

removable ends

27 and 28, the latter of which is shown almost wholly broken away in FIG. 2. Within switch 34 contained within module 35 ofthe cluster shown in FIG. 4. To assure that the fuse 33 is not manually disconnected without first having opened disconnect switch 34, a latch 36 is mounted on a'panel 37 of the service center in such manner that it overhangs the end of fuse cap 330, thus preventing removal thereof from-the module 32 unless and until switch cap 340 is first removed. To accomplish the latter, latch 36 is pivotally mounted upon a bolt 38 extending through the insulating panel 37, and is contoured as shown in FIG. 18, so that the lower apron portion 39 overhangs the upper half of the end of fuse cap 330, while the upper portion 5 40 of latchl 36 fits beneath switch cap 340, and is thereby prevented from being rotated in the clock-wise direction', as seen in FIG. 2, unless and until the switch cap 340 is moved out of the way.

The internal construction of module 32 is illustrated in FIG. 8, which is a section taken along line 8-8 of FIG. 12, i.e., diamet'ricalsection of the capsule 41 and its contained conductive parts (except that portions of the conductive parts are shown in elevation). The capsule 41, of moldable insulating material, was preferably molded with spaced electrically conductive fuse-engaging

parts

42 and 43 in situ. Such a capsule as 41, when cast about the electrically conductive parts as shown, produces the fuse module 32 seen in FIGS. 2, 3, 4 and 6. The conductive part 42 consists of a ring 44, having a cylindrical stud 45 projecting radially outward therefrom. Through the wall of capsule 4l, there extends a cylindrical sleeve 46 which embraces a stud 45 and a split metallic tube 47 of pro# portions such that the split 48 must be forced open slightly to engage over stud 45, so that when the opening force is relaxed, the' resilience of the lcounterpart thereof in module 35 later to be described.

f At the closed end of capsule 41, there is a cup-shaped base 43 having a lug 31 extending outwardly through the wall of the capsule 4l. The capsule is also preferably molded about such base and lug. A bifurcated resilient clip 49 is also mounted in the cup-shaped part 43,`so as to resiliently grip the conductive thimble 50 of a fuse cartridge 51, such as that shown in FIG. 10. The opposite end of the fuse cartridge has a thimble 52 provided with a circumferential bead 53, and the fuse cap 330 has a pair of jaws 54 (see FIG. 13) which terminate in a discontinuous channel 55 of curvature such as to be congruent with that of the bead 53 on the fuse cartridge. The jaws 54 are mounted upon an interior portion of the insulating fuse cap 330 by means of a bolt 56 and nut 57, which may be relaxed to permit the insertion and removal of a fuse cartridge, such as 51, from between the opposite jaws 54; and when a new fuse is inserted, the bolt-nut combination 56-57 may be tightened down over the bead ofthe new fuse cartridge. Each of the jaws 54 is equipped with a pair of resilient tangs 58 for electrically conductive engagement with the inner'periphery of ring 44 when a fuse cartridge and the fuse cap are in the position shown in FIG. 6. v

The module 35 previously referred to is the center one of three substantially identical modules shown in FIG. 5, and the outer ones are designated 59 and 60, respectively. Each of these thre'e modules is constructed of identical'parts, save in one particular to be noted hereinafter. Each includes an insulating capsule 61formed of moldable dielectric material. One such capsule is shown in FIG. 7, .and consists of a wall of dielectric material substantially circular in cross-section which was molded about an assembled pair of half-liners 62 and contents of the character shown in FIGS. 7, 14, and 16. The use of an interior sub-assembly of half-liners 62 and contained components, is a matter of economy because it enables less of the complete capsule to be made of more expensive arc-resisting material than would be desirable without the liner assembly.

In the embodiment shown in FIGS. 7 and 17, the half-liners 62 are cast parts of insulating material which resistant, but may, if desired, have some arc-suppressing qualities, depending upon the material of which they are made. Adjacent the closed end of half-liner 62, .there is a stationary contact assembly consisting of a ring 63 (see FIG. 14) of conductive material having riveted thereto four resilient conductive fingers 64 and a metallic bridge 65 having a central aperture 66. Integral with the ring 63, there are two

studs

67 and 68 of cylindrical cross-section, the latter of which, as seen in FIG. 7, is substantially shorter than the former, which is the condition in which the element is employed in

modules

59 and 60. In module 35, on the other hand, the construction is as shown in FIG. `14, where the studs 67 and 68' are of the same length radially of ring 63. i

split tube 47 grips stud 45, as well as the is not only arc- The construction of the stationary contact assembly at the closed end of module 35 differs from that at the closed ends of

modules

59 and 60, and is dictated by the fact that the invention contemplated connecting the contact assemblies at the closed ends of all three

modules

59, 35, and 60 in permanent electrical series. This requires that the center module 35 have its studs 67 and 68' extend as far in both directions as the stud 67 extends in one direction for

modules

59 and 60. This dfference in the length of stud 68 versus stud 68 does not, however, necessitate any change in the mold in which the three capsules 6l are made. All such capsules are preferably made with accommodation at both sides for only a short stud, such as 68, so that the section of wall delineated by dotted lines in FIG. 7 and designated 694may be drilled out or left intact, as desired, depending upon the ultimate disposition of the particular capsule in the complete cluster.

As described in connection with shown in the broken-away portions of FIG. 5, stud 67 of module 59 is electrically connected with stud 68' of module 35 by means of a split resilient tube 70 of conductive material which may be confined within a sleeve 71. And an identical connection is made between

modules

35 and 60.

The stationary contact assembly located toward the open end of

modules

59, 35 and 60 is illustrated in FIG. 15, and is similar with that shown in FIG. 14, but differs in that it has no bridge like 65, and in that, in all instances, the relative lengths of the

radially projecting studs

72 and 73 are as shown in FIG. l5 (which is comparable to that shown in FIG. 7 for the contact assembly at the closed-end of an outside module). However, the stud 73 is axially bored and threaded as indicated at 74 to receive a bolt to which lugs 75 and 76 for modules 59.

and 60 respectively may be connected, as shown in FIG. 12, while on module 35, the boring and threading 74 is not necessary, but it does no harm in effectuating the connection sh'own in FIG. 6 between module 35 and module 32, which again is of the same split sleeve type as that previously described.

To complete a circuit between the spaced stationary contact members in any one of the three

modules

35, 59, and 60, each is provided with a removable stab such as that shown in FIG. 9. Such a stab consists of an insulating cap 34 having a pilot portion 77 in which is anchored one end of a rod 78 of copper, or other conductive material, having a tapered nose 79 which may, if desired, be tipped with arc-resisting material such as copper-tungsten alloy. The length of the rod 78 is at least sufficient that the tip 79 has passed through and beyond the locus of engagement with fingers 64 before the insulating cap 34 has come to rest against the open end of the module. When the last-mentioned position is reached, the fingers 80 of the Contact assembly, shown in FIG. 15, will be in conductive engagement with rod 78, thereby completing a circuit between stud 73 and its associated components, and stud 67 and its counterpart in all three

modules

59, 35 and 60.

The correlation of the several contacts in the diagrammatic showing of FIG. l with the physical showing of FIGS. 2-8, l2, 14 and l5 will be clear to persons skilled in the art from the following table:

Module Contact Diagrammatic Side 59 80 equates with 17 Right 59 64 equates with 17 Left 60 80 equates with 18 Right 60 64 equates with 18 Le 35 64 equates with 34 Right 35 80 equates with 34 Left 36 44 equates with 33 Right 36 43 equates with 33 Left FromA FIG. 17, it will be apparent that the identical halfliners 62, two of which constitute a complete liner assembly for use on the interior of the capsule of each disconnect switch module, are constructed not only to accommodate the relathe fuse module 32, and as tively stationary contact assemblies shown in FIGS. 14 and 15, but also to delineate a constricted passageway between said stationary contact assemblies. Furthermore, each such halfliner is compartmentalized lengthwise by spaced partitions 81, so that the space occupied by the relatively stationary contacts 64 is substantially isolated from the space occupied by the relatively stationary contacts 80; and between the two, there is accommodation for a plurality of sets of arc-quencher elements 82, one of which is illustrated in FIG. 16. These arcquencher elements are, in the form illustrated, substantial segments of a cylinder of melamine resin, or other moldable material` having arc-quenching properties. In FIG. 16, the planar side of the segment is addressed toward the reader, and it will be observed that a half-conical recess 83 is formed at one side of the planar surface. ln one or more of the compartments delineated by partitions 81, a pair of the arc-quenching wipers or clappers 82 is'mounted with its individual segments arranged so that the recess 83 of one complements the recess 83 of its companion when the rod 78 of the switching stab is removed. Thus, the disposition of the recesses 83 in paired clapper elements is in position to funnel in the tip 79 of rod 78 when next inserted, and to guide the rod between the paired clapper elements 82.

On the arcuate side of each clapper segment 82, there is a recess 84, shown in dotted lines in FIG. 16, for accommodating a spring 85, which is seated on a boss 86 projecting upwardly from one half of the liner, and downwardly from the other half, as clearly shown in FIG. 7. Such spring mounting of the clapper segments 82 resiliently urges them toward each other,`so that when, during the withdrawal of rod 78, the tip 79 departs from between a given pair of clappers 82, they clap together, inserting thearc-guiding material directly into the path of the established arc, and thereby causing the emission of arc-suppressing gases. As clearly shown in FIG. 17, each of the partitions 81 has a central arcuate cutout 87 which together not only define a passageway for the rod 78, but constrict that passageway at tive separated locations.

The two halves 62 of the composite liner are identical, and are assembled together in reverse orientation, so that circumferentially one truly complements the other, and they interlock along their parting line with a tongue and groove connection, the tongue 88 extending along the right half (as seen in FIG. 17) of the perimeter, and the groove 89 extending along the left half.

As shown in FIGS. 2 and l2, the studs 73 of the stationary contact assemblies near the open ends of

modules

59 and 60 are respectively equipped with

terminal lugs

75 and 76 for removably receiving the end of cable90 and the end of cable 91, respectively. The cable end V90 is one terminal of a section of the underground loop 1l, as, for example, the section thereot` which extends between switches 16 and 17 in FIG. 1. The cable end 91 is one terminal of an adjacent section of the underground loop 11, as, for example, the section thereof which extends between

switches

18 and 19 in FIG. 1.

As shown in FIG. 12, the

lugs

75 and 76 may each be equipped with a stirrup 92 which provides a convenient place for applying a grounding clamp, while the service controlv center is being connected, disconnected, or worked on. The

cables

90 and 91, as well as the

terminals

75 and 76 and the associated stirrups 92, are, of course, disposed behind the insulating panel 37, as seen in FIG. 2.

Flg. 11 illustrates an alternative form of fuse module which differs from that shown in FIG. 8 in the respect that the clip 149, which is the counterpart of clip 49 in FIG. 8, has a terminal post 150 which extends out through the end of the dielectric capsule, rather than out through the bottom as shown for 3l in FIG. 8.

As clearly shown in FIGS. 2 and 3, the service center also includes a meter 93 connected in the circuit 94 of the transformer secondary, and the meter is disposed so that its dial can be read through a window 95 without removing end panel 27.

From the foregoing description, those skilled in the art should understand the invention and realize that the service center is intended to be mounted at or near ground level, so that it is conveniently accessible whenever there is need for authorized persons to manipulate one of the disconnect switches, or to inspect or replace the fuse. Such location of such an apparatus has,v by some alarmists, been considered to pose a hazard to children whose curiosity may lead them to remove a cover. Accordingly, the removable ends 27 and 28 are each equipped with a latch 96, manipulable only by turning a keeper 97, and the keeper is arranged to be padlocked, in the position shown in FIG. 3, by having the bow of the padlock extend through the hole 98 in the keeper, as well as a hole in lug 99 thereadjacent.

The modular arrangement of control and protective devices herein disclosed is substantially safe because with the permanent electrical connection of the substantially stationary contacts at the closed end of each disconnect switch module, the arc drawn when the stabs of either module 59 or module 60 are withdrawn is minimal, and when the stab of module 35 is withdrawn, `the only circuit interrupted is that which leads directly to the transformer component of the particular service center and none other'. As previously pointed out, the fuse module cannot, because of the interlocking relationship of latch 36, be moved out of operating position without first open-circuiting the disconnect switch in module 35` In sum, no hazardous arc can be drawn from the apparatus disclosed if the stabs of the respective disconnect switch modules are withdrawn rapidly and inserted rapidly. To completely eliminate the hazard involved when unskilled persons manipulate the parts of the apparatus exposed on the insulating panel 37 when cover 28 is removed, the length of the

modules

35, 59, and 60, as well as the length of the insulation-handle on the stab shown in FIG. 9, may be increased so that the modules are nearly twice aslong as their liners 62, and the insulation on the stab extends from the inside of cap 34 for a distance at least equal to the distance the tip 79 of rod 78 must travel from the position shown in FIG. 7 to a position where rod 78 has lost contact with fingers 80 and their associated electrically-live parts. With such increase in length of the several modules, it becomes impossible for a person to touch any part of rod 78 while that rod is in conductive relationship with a stationary contact of the module.

In the foregoing description, the capsules suchas 41 and 61, which form the insulatingenclosures (save at one end) of the

several modules

32, 35, 59 and 60, have been described as each being individually molded in one piece, but it should be understood that Yif and when desired: the dielectric capsules can be of pluri-piece construction, assembled about the conductive and arc-snufting parts, and securely unified together as by solvent or thermal sealing, or otherwise; or given the requisite molding equipment, the entire cluster of capsules can be molded in one integral piece. Moreover, since for service centers like that including transformer 21 the cluster of capsules may be reduced to two (one like 32, the other like 35 it is feasible to mold those two capsules in one piece for optional addition of capsules like 59 and 60 when the cluster is to be used in service centers like that including

single dwelling transformer

22, 23, or 24.

While one complete embodiment of the invention has been disclosed in detail, and various modifications described, it is not to be understood that the invention is limited to the details of the foregoing disclosure.

We claim:

l. Sectionalizing and protective apparatus for single dwelling transformers comprising a cluster of:

a. three capsules of moldable insulating material;

b. another capsule of moldable insulating material; all said capsules having one end open and one end closed, said said partitions being centrally relieved to provide a passageway extending axially from said open end toward but terminating short of the closed end of said capsules, and said capsules (b) having a central passageway of greater radial dimension than that in said partitions; said capsules each having cast therein:

e. a pair of resilient contacts near opposite ends of and adjacent the respective passageways;

said capsules (a) having:

f. conductive means extending from the resilient contacts at one end of the respective capsules to connect the corresponding resilient contacts in allcapsules (a) together; and

at least two of said capsules (a) having:

g. conductive means extending from the resilient contact at the other end of said passageway to the exterior of said capsules for connection with a source of power.

2. The apparatus of claim 1 wherein the capsule (b) accommodates a fuse, and the resilient contact at one end thereof is conductively connected to the conductive means (g) of one of said capsules (a).

3. The apparatus of claim l wherein each capsule (a) is provided with removable stab means for interconnecting the resilient contacts (e) thereof, and said stab means includes a manipulating part of insulating material which is disposed on the exterior of a capsule when the resilient contacts (e) thereof are interconnected by said stab means.

4. A circuit interruptor comprising a capsular cast of moldable insulating material and having a hollow interior and at least one open end, a first relatively stationary resilient contact mounted in said hollow interior remote from said open end, a second relatively stationary resilient contact mounted in said hollow interior in spaced relationship with the first but nearer said open end, compartment means defining a constricted passageway between said first and said second relatively stationary contacts, arc-snufting means adjacent said constricted passageway, a removable stab having:

a. a conductive part of length sufficient to bridge the gap between said relatively stationary contacts, and

b. an insulating part extending outwardly beyond said conductive part for a distance sufficient that when the conductive part engages the First-mentioned resilient contact, said insulating part occupies said open end and extends outwardly of said capsular cast, and

fixed conductive means extending from said relatively stationary contacts respectively through said capsular cast to provide connecting terminals.

5. The circuit interruptor of claim 4 wherein said relatively stationary resilient contact remote from said open end is an assembly of:

c. a support member having an outside peripheral contour substantially matching the inside peripheral contour of said hollow interior, Y

. oppositely disposed resilient finger members mounted in circumferentially spaced relationship on said support member,

. a bridging member of conductive material mounted on said support member in electrically conductive relationship with said finger members and having a central hole to accommodate passing of said conductive part (a) therethrough` and conductive means projecting radially' outward from said support member through the wall of said capsular cast.

Claims

1. Sectionalizing and protective apparatus for single dwelling transformers comprising a cluster of: a. three capsules of moldable insulating material; b. another capsule of moldable insulating material; all said capsules having one end open and one end closed, said capsules (a) being internally subdivided by radially extending partitions to provide: c. compartments at opposite ends thereof for accommodating paired relatively stationary and resilient electrical contacts, and d. at least one intervening compartment for accommodating arcextinguishing means, said partitions being centrally relieved to provide a passageway extending axially from said open end toward but terminating short of the closed end of said capsules, and said capsules (b) having a central passageway of greater radial dimension than that in said partitions; said capsules each having cast therein: e. a pair of resilient contacts near opposite ends of and adjacent the respective passageways; said capsules (a) having: f. conductive means extending from the resilient contacts at one end of the respective capsules to connect the corresponding resilient contacts in all capsules (a) togeTher; and at least two of said capsules (a) having: g. conductive means extending from the resilient contact at the other end of said passageway to the exterior of said capsules for connection with a source of power.

3. The apparatus of claim 1 wherein each capsule (a) is provided with removable stab means for interconnecting the resilient contacts (e) thereof, and said stab means includes a manipulating part of insulating material which is disposed on the exterior of a capsule when the resilient contacts (e) thereof are interconnected by said stab means.

4. A circuit interruptor comprising a capsular cast of moldable insulating material and having a hollow interior and at least one open end, a first relatively stationary resilient contact mounted in said hollow interior remote from said open end, a second relatively stationary resilient contact mounted in said hollow interior in spaced relationship with the first but nearer said open end, compartment means defining a constricted passageway between said first and said second relatively stationary contacts, arc-snuffing means adjacent said constricted passageway, a removable stab having: a. a conductive part of length sufficient to bridge the gap between said relatively stationary contacts, and b. an insulating part extending outwardly beyond said conductive part for a distance sufficient that when the conductive part engages the first-mentioned resilient contact, said insulating part occupies said open end and extends outwardly of said capsular cast, and fixed conductive means extending from said relatively stationary contacts respectively through said capsular cast to provide connecting terminals.

5. The circuit interruptor of claim 4 wherein said relatively stationary resilient contact remote from said open end is an assembly of: c. a support member having an outside peripheral contour substantially matching the inside peripheral contour of said hollow interior, d. oppositely disposed resilient finger members mounted in circumferentially spaced relationship on said support member, e. a bridging member of conductive material mounted on said support member in electrically conductive relationship with said finger members and having a central hole to accommodate passing of said conductive part (a) therethrough, and f. conductive means projecting radially outward from said support member through the wall of said capsular cast.