US2824190A - Circuit interrupter construction - Google Patents

Description

Feb. 18, 1958 J J. MIKOS I CIRCUIT INTERRUPTER CONSTRUCTION Filed March 14. 1956 4 Sheets-Sheet 1' mmvron.

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Feb. 18, 1958 J. J. Kos. 2,824,190

CIRCUIT INTERRUPTER CONSTRUCTION Filed March 14, 1956 4 Sheets-Sheet 2 V x I V l I I \l IN V EN TOR.

Ja/zzz XML/m5,

Feb. 18, 1958 J, os 2,824,190

CIRCUIT INTERRUPTER CONSTRUCTION Filed.March 14, 1956 4 Sheet S-Sheet 3 INVEN TOR.

John JMZ/tas;

Feb. 18, 1958 J, 4. os v 2,824,190

CIRCUIT INTERRUPTER CONSTRUCTION Filed March 14, 1956 C I 4 Sheets-Sheet 4 INVENTOR.

CIRCUIT INTERRUPTER CONSTRUCTION John J. Mikos, Highland Park, Ill., assignor to S & C

Electric Company, Chicago, Ill., a corporation of Delaware Application March 14, 1956, Serial No. 571,472

14 Claims. (Cl. 200-114) This invention relates, generally, to the construction of electric circuit interrupters and it has particular relation to circuit interrupters of the portable type adapted to be carried by a live line stick for opening disconnecting fuses, disconnecting switches and the like under load. It constitutes an improvement over the inventions shown in Lindell application Serial Nos. 493,083, filed March 9, 1955, now abandoned, and 569,909, filed March 16, 1956. This application is a continuation-in-part of application Serial No. 529,880, filed August 22, 1955.

Among the objects of this invention are: To adapt the circuit interrupter disclosed in said copending applications for use with various types of disconnecting devices; to provide for receiving various types of contact members on the terminal of the circuit interrupter that is employed for engaging and making electrical contact with the stationary contact member of the fuse or switch; to employ a minimum number of different parts to make up the contact assembly; to employ a bow shaped contact member for one of the contact assemblies and a contact arm for another of the contact assemblies; and to provide a simple and efiicient construction for detachably mounting a pull ring end cap on a bushing on the end of the housing of the circuit interrupter, the pull ring being provided in one instance with the bow shaped contact member and in another instance with a rigid contact arm.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

This invention is disclosed in the embodiments thereof shown in the accompanying drawings and described hereinafter and the scope of the application of which is indicated in the appended claims.

For a more complete understanding of the nature and scope of this invention, reference can be had to the following detailed description, taken together with the accompanying drawings, in which:

Figure l is a view, in side elevation, of a disconnecting fuse with which the present invention can be employed for opening it under load;

Figure 2 is a perspective view of certain parts of the disconnecting fuse and auxiliary circuit interrupter showing how the latter is applied to the former.

Figure 3 is a top plan view of the auxiliary circuit interrupter showing only the construction of the upper terminal;

Figure 4 is a view, in side elevation, of the construction shown in Figure 3;

Figure 5 is a vertical sectional view taken generally along the line 5-5 of Figure 3;

Figure 6 is a view, in side elevation, of another form of disconnecting fuse, such as that shown in United States Patent No. 2,703,349, issued March 1, .1955, with which the present invention can be used;

Figure 7 is a perspective view of a portion of the fuse shown in Figure 6 and of the auxiliary circuit interrupter, showing how the latter can be applied to the former;

Figure 8 is a top plan view of the upper terminal oi build the circuit interrupter shown in Figure 6, modified to adapt it for use with the fuse there shown;

Figure 9 is a view, in side elevation, of the construction shown in Figure 8;

Figure 10 is a vertical sectional view, similar to Figure 5, and showing the details of construction of the upper end of the auxiliary circuit interrupter that is shown in more detail in application Serial No. 569,909, filed March 6, 1956;

Figure 11 is a top plan view of the bushing employed in the construction shown in Figure 10;

Figure 12 is a vertical sectional view taken generally along the line 12-12 of Figure 11;

Figure 13 is a top plan view of the detachable contact member which telescopes over the bushing of Figure 11;

Figure 14 is a vertical sectional view taken generally along the line 1414 of Figure 13;

Figure 15 is a view, in side elevation, of a key which is applied to the pull ring end cap portion of the contact member shown in Figures 13 and 14;

Figure 16 is a top plan view of a crescent shaped spring member that is employed for retaining the detachable 'contact member 78 in place on the bushing;

Figure 17 is a top plan view of a modified form of detachable contact member that is to be employed in lieu of the contact member shown in Figures 13 and 14; and

Figure 18 is a vertical sectional view taken generally along the line 18-18 of Figure 17.

Referring now particularly to Figure 1 of the drawings, it will be observed that the reference character 10 designates, generally, a disconnecting fuse. The disconnecting fuse 10 includes a supporting insulator 11 which can be mounted, as is conventional, on a cross arm or the like. At its upper end the insulator 11 carries an upper terminal contact member, indicated generally at- 12, which includes a terminal 13 that is arranged to be connected to a normally energized conductor. Thus the upper terminal contact member 12 is nonnally energized and is so referred to hereinafter. In contact engagement with the upper terminal contact member 12 is a current carrying member 14 which is mounted on the upper end of a fuse tube 15. The fuse tube 15 is pivoted, as shown, on a lower terminal contact member that is indicated at 16 and mounted on the lower end of the insulator 11.

It will be noted that the upper terminal contact member 12 includes a generally U-shaped guide that is shown, generally, at 19 in Figures 1 and 2. The guide 19 is normally energized along with the upper terminal contact member 12 and includes forwardly extending arms 20 having rearwardly turned horns or studs 21 at their outer ends. Associated with the current carrying mem ber 14 on the upper end of the fuse tube 15 is an eye or pull ring 22. As will appear presently, provision is made for establishing a shunt circuit between the guide 19 and the eye or pull ring 22 in order to permit separation without arcing of the current carrying member 14 from the upper terminal contact member 12 while carrying load.

In order to provide the shunt circuit just referred to,

an auxiliary circuit interrupter, shown generally at 23, is employed. Since the details of construction of the auxiliary circuit interrupter are set forth fully in the above identified application Serial No. 493,083, the same will not be set forth herein. The auxiliary circuit interrupter 23 is detachably mounted at 24 on a fitting 25 which is carried at the upper end of a live line stick 26. It will be understood that the live line stick 26 is manipulated by the lineman or operator to maneuver the auxiliary circuit interrupter 23 into operating position and for operating it in a manner to be described.

, The auxiliary circuit interrupter 23 includes a tubular insulating housing 27 which carries at its upper end an,

or strut 30 on which theauxiliary-cir'cuit interrupter 23" is pivotally mounted, as described more fully in the'application above referred to. Neartlie upper end of the strut is apin or. prong. 31which is arranged to extend through .theeye orpull ring 22.. A rotarykeeperSZT cooperates with the pin .or prong31 to maintain connection with the eye or pull ring 22;

The details of construction. of. the .upper .or= firstterminal 28 are shown more :clearly in- Figures.3,.4 .and. 5 ofthe drawings. As there.shown,.a. metallic bushing; 36

is secured to the upper end.:of:the;tubular insulating housing, 27.:and. its upper end..is threaded .for receiving a screw. plug 37. Formedintegrally with the. bushing 36 :isuanuannular rib '38. Surrounding a. portion of. the bushing 36 is a semi-circular fitting 39 whichhas .a cen-.

trally located groove 40. intermediate its ends for receiving a portion of-theannular rib 38 andlaterally extending ears 41.

Cooperating with the fitting 39 is a contact member that'isrindicated', generally, at- 42;. his detachably mounted on the: bushing 36 by'being detachablyconnectedtto thefitting39. As shown, the contact member 42 includes asemi-circular portion 43 which is generally similar to the fitting39." It has. a groove 44 intermediate itsendsfonreceiving the remaining portion I of the rib 38 and laterally projectingears 45 which have threaded oP.nings that registerwith openings in the ears 41. Screws -46 :serve -to detachably, connect the semi-circular! portion 43rof'the contact member-42 m the fitting39. If desired, provision can .bemade for forming-the fitting 39.:integrally-withthe:bushingfifi. Alternatively, pro-- 5 vision canwbe made for boltingpr'v otherwise detachably' securingthe semi=circular portion-1.43 of the contact mem ber 42 directly; to. thebushing. 36. Extending, generally radiallygfrom thersemi-circular portion 43 are arms 47 between .whicha bow shaped contact member 48 is pivotally mounted. at 49.

Theoperation of the." auxiliary circuit interrupter 23 as. thusfar described: will be clear'from a consideration of Figures .1 and 2, It willbe assumed that the currentis flowing from the normally energizedterminal 13..through the .disconnectirigifuseltl toa linethat is .CODIRCtBdJ/[Ol the: lowerz'contact member: 16. Further; itwillbe assumedthatthe:fuse:tube 15 is 'toi'beswungto the open position: under. these :conditions; i.

The lineman manipulateszthe IiyeLIineJstick .26 to such; 50

positionzthat the bowi'shapedacontact member .485overlies one of thehorns oristudsxZl, as:shown:in."Figure. 2.. In. addition; the pin .or prong 31is "caused itoengage the .eye or .pull ring. 22, as-shown inFigure- 1.. Thisplacesthe auxiliary circuit interrupter-136m. shunticircuiturelation with the upper terminal contact member .125and..the .cur- I rent carryingmember 14. Itis nowsafe to swing:the fuse tube 15 to the:open:-position and disengage the :current carryingmember '14 from the upper terminalcon tact member 12 since no arc will be formed therebea tween'when this .takesplace because of the shunt circuit through the auxiliary-circuit interrupter 23. The dineman pulls downwardly on-the live linestick 26.:and,..

since theipin or prong 31-engages the eye or-pull. ring... 5

22,thefuse tube 15 is swung toward the openwposition.

The bow shaped contact memberfi-fi remains iniengage ment with the born or stud 21 *whilethe live line 'sticie 26 is pulled l downwardly." After the: currentflcarryingf member 14 is separated fromtheuppenterrninalhcontact. member 12, the entire current 'flow takes place through: the auxiliarycircuit interrupter23. As described 'inztheabove applicatiomthe continued downward movement of the live Iine-stick-26 causes tlteauxiliary circuit interrupter23 tooperate and interrupt the flow' of current 75 within-the tubulaninsulating housing'27. Thereafter, the auxiliary circuit interrupter 23 is rotated to such position that the pin or prong 31 disengages the eye or pull ring 22. The fuse tube 15 then drops or swings to the full open position. The bow shaped contact member 48 is lifted off of thehorn or stud 21 and the operation has been completed.

In Figures 6'and 7of'the drawings, a different type of .disconnecting fuse is indicated; generally; at 52. i That.

fuse includes an insulator 53 which is 7 adapted to be mounted on a conventional cross arm. At the upper end of the insulator53 is an upper terminal contact .member 54 which includes a terminal portion 55 that is connected to a conductor thatis normally energized. In engagement with the upper terminal contact member 54 is a current carrying member 56 that is mounted on the upper end of a fuse tube .57. The fuse tube 57is pivotally mounted on a lower terminal contact member 58-whichis mounted, as shown, at thelower end of the insulator 53. This contact member 58is connected to a load circuit, as will be readily understood.

It will'be observed that theupper terminalcontact member 54 includes a pair of contact springs 61 which are extensions of the terminal portion 55, These contact springs 61 engage the current carrying-member 56" at the upper end of the fuse tube 57 whichhasan eye or pull ring 62 extending therefrom.

In accordancewith the present invention, provision is made for providing a shunt circuit between thecontact springs 61 of the upper terminal contact member 54 and the eye or pull ring 62 which projects from the current carrying member.56. For this purpose, the auxiliary circuit interrupter23, previously described, is used. However, ,it is modified in. order to adapt it for use with the particular configurationof the contact springs 61' As shownmore clearly in Figures 8 and 9 of thedrawings, an upper or.fir-st terminal-63 is provided at-the upper endof the tubular insulating housing-27. This terminal .63 corresponds to the terminal 28 previously described. Theupper-or' first terminal 63 "includes the semi-circular fitting. previously described, together with a the bushing 36. Italso includes a contact member 64 having a semi-circular portion 65 which correspond to thesemi-circular portion 43 of the contact member 42. It also has a groove 66 intermediate its ends for overlying the.annular rib. 38.-of the bushing 36 andears 67 overlyingthe ears 41.. The screws .46 are hereemployed to secure the earsc67 oftthe semi-circularportion 65 detachably to the semi-circular fitting 39.

Projecting.radiallyoutwardly from the semi-circular portionfiiis'acontact arm-68that has a downwardiy extending tip 69 at its outer end for preventing the contact arm 68 from slipping ofi ofthecontact spring61.

. In describing: the operation of the auxiliary circuit'interrupter 23 in conjunction with the disconnecting fuse 52, it will be assumed that the'latteris carryingload current and that the fusetube- 57 is to be'swung to the open position without arcingbetween the upper terminal contact member 54 and the current carrying memberi56.

For this purpose, the lineman manipulates the live line stick 26 to position the contact-arm 68"within one of thestick 26-:and,-since the pin-"or prong 31 is-in engagementwithilheieye or pull. ring '62; the current carrying. member. 56 is moved out of engagement awith themppertierminaltcontactmember 54- and the entire fiow of current is transferred to the auxiliary circuitinterrupter 23;". Continued pulling-'on'the live= line -sticl-:--26 'causes*the circuit to be .1

opened within the tubular insulatingmousing-27. T There after, the live line stick 26 is rotated to disengage the pin or prong 31 from the eye or pull ring 62. The fuse tube 57 is permitted to fall to the open circuit position. The contact arm 68 is removed from the contact spring 61 and the operation is completed.

It will be noted that the contact member 64 is substituted in the construction shown in Figures 8 and 9 for the contact member 42 shown in Figures 3, 4 and 5. In order to adapt the auxiliary circuit interrupter 23 for use with either the disconnecting fuse 10, shown in Figure 1, or the disconnecting fuse 52, shown in Figure 6, the appropriate change is made in the assembly of the upper or first terminal 28 or 63, as the case may be.

Referring now particularly to Figures -18 of the drawings it will be observed that modified forms of the detachable contact member are there shown. Referring particularly to Figure 10 it will be observed that it shows a modified form of auxiliary circuit interrupter generally at 70 the details of construction of which are set forth in application Serial No. 569,909, filed March 6, 1956. The auxiliary circuit interrupter 70 includes a tubular insulating housing 71 which is provided at its upper end with an upper or first terminal that is indicated, generally, at 72.

The upper or first terminal 72 includes an annular bushing 73 that is secured by a suitable cement to the upper end of the tubular insulating housing 71. The details of construction of the bushing 73 are shown more clearly in Figures 11 and 12 of the drawings. Near its outer end the bushing 73 is provided with an annular groove 74, the purpose of which will be apparent presently. At its other or lower end there is a radially outwardly projecting flange 75 which has a transverse keyway 76 therein. A screw plug 77, Figure 10, is threaded into the outer end of the bushing 73.

Telescoped over the bushing 73 is a detachable contact member that is shown generally at 78 and its details are illustrated more clearly in Figures 13-15. It includes a pull ring end cap portion 79 that is circular and is arranged to telescope over the circular portion of the bushing 73. At its inner end the portion 79 is provided with an annular groove 80 that is arranged to receive the flange 75 that projects radially outwardly from the inner end of the bushing 73. This serves to limit the downward movement of the contact member 78 when it is placed in position on the bushing 73. A radial opening 81 is formed in the wall of the pull ring end cap portion 79 in which the groove 80 is located for receiving a reduced diameter portion 82 of a key 83. The reduced diameter portion 82 has a press fit with the opening 81 and the key 83 is of the same height as the height of the groove 80 and is arranged to interfit with the keyway 76 in the flange 75 on the bushing 73 to hold the contact member 78 against rotation.

The contact member 78 also includes laterally extending arms 84 for carrying therebetween a bow shaped contact member 85 which is pivotally mounted at 86 on the outer ends of the arms 84. The function of the bow shaped contact member 85 is the same as that of the similarly shaped contact member 48 previously described. Intermediate the arms 84 is a flange 87 which is provided with a downwardly opening pocket 88 to receive a nose portion of a member that can be detachably mounted on the strut 30 for unitary operation of the strut and auxiliary circuit interrupter 70 as described in more detail in application Serial No. 569,909, filed March 6, 1956.

In order to hold the contact member 78 against upward movement from the bushing 73 a crescent shaped spring member 89, Figure 16, is employed. It is positioned in the annular groove 74 in the bushing 73 as illustrated in Figure 10. It is held there by frictional engagement and it can be removed readily to permit removal of the contact member 78.

An insulating cap 90 extends over the upper or first terminal 72 as shown in Figure 10.

As previously described it is desirable to provide for applying the auxiliary circuit interrupter 70 to various types of disconnecting fuses and disconnecting switches. The contact member 78 is intended for use particularly with the disconnecting fuse 10 shown in Figure 1 of the drawings and described hereinbefore. For operation with a disconnecting fuse of the type shown in Figure 6 of the drawings a detachable contact member, indicated generally at 93, in Figure 17, can be used. It is constructed so that it can be applied to the bushing 73 when the contact member 78 has been removed therefrom.

The details of constructon of the detachable contact member 93 are shown more clearly in Figures 17-18 of the drawings. It includes a pull ring end cap portion 94 which is similar to the portion 79 of the contact member 78 previously described. At its inner end it is provided with an annular groove 95 for overlying the flange 75 on the bushing 73. A radial opening 96 is employed for receiving a reduced diameter portion 97 of a key 98 which is similar to the key 83 previously described and is similarly applied. The key 98 cooperates with the keyway 76 to prevent relative rotation between the contact member 93 and the bushing 73.

Extending radially from the pull ring end cap portion 94 is a contact arm 99 which has a downwardly extending tip 100 to facilitate retention on a member such as the contact spring 61 of the disconnecting switch 52 shown in Figure 6. A pocket 101 is formed on the underside of the contact arm 99 and serves the same function as the pocket 88 located on the underside of the flange 87.

Since certain further changes can be made in the foregoing construction and different embodiments of the invention can be made without departing from the spirit and scope thereof, it is intended that all matter shown in the accompanying drawings and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

What is claimed as new is:

1. In a circuit interrupter for opening a high voltage circuit isolating device such as a disconnecting fuse, disconnecting switch or the like, normally carrying line cur rent and having a normally energized terminal contact member and a current carrying member movable into and out of engagement therewith comprising, in combination, an insulating housing enclosing circuit interrupter means; a first terminal carried by said housing including a bushing secured thereto, a laterally extending contact member for engaging said normally energized terminal contact member including an arcuate portion overlying said bushing, and means detachably clamping said arcuate portion to the lateral circumferential surface of said bushing; and a second terminal carried by said housing and movable relative to said first terminal having a prong extending generally parallel to said laterally extending contact member for engaging said current carrying member and moving it out of engagement with said contact member on movement apart of said terminals.

2. In a circuit interrupter for opening a high voltage circuit isolating device such as a disconnecting fuse, disconnecting switch or the like, normally carrying line current and having a normally energized terminal contact member and a current carrying member movable into and out of engagement therewith comprising, in combination, an insulating housing enclosing circuit interrupting means; a first terminal carried by said housing including a bushing secured thereto, a contact member for engaging said normally energized terminal contact member including an arcuate portion overlying said bushing and having a pair of outwardly extending arms with a bow shaped contact member pivotally mounted therebetween, and means detachably clamping said arcuate portion to said bushing; and a second terminal carried by said housing and movable relative to said first terminal for engaging said current carrying member and moving it out of engagement with said contact member on movement apart of said terminals.

3. The invention as set forth in claim 1 wherein the laterally extendingrcontact memberincludes a contact armextending radially-zoutwafdly from the arcuate por'tion: 4; The invention as set forth in' claim lwherein the bushing is annul'ar and has a radially:outwardlyprojectinga rib"intermediate its endsgthe arcuate' portion of the contacfmer'n'be'r is 'semi-circular ahd has a groove-inter fittingwith saidrib and outwardlyl'extending:ears at its ends, and-the clamping "means includes a serni-circular fitting having a groove interfi ttingi-with said rib, ears at its ends registering' with said ears-on sai'd arcuate' portion, and 'means extending between said regi'sterrng ears detachably interconnectingt'the same to-hbld said arcuate portion'and said-fitting'zin place"0nsaid bushing;

SuThe invention asset forth 'in claim '4*wherein"th'e arcuate portion 'of the co'nta ct memberhas a'pair of outwardly extending 'arms with'a bbw shaped contact member pivotallymounted-'therebetween. 1

6. The invention-"asset forth'in' claim' 4 wherein the arcuate portionof the contact member-has aradially;outwardly extending contact arm.

7. In a circuit interrupterfor opening a high voltage circuit isolating device such as a disconnecting fuse, disconnecting switch or the like, normallycarrying line current and having a normally energizedterminal contact member and a current carryin'gnmember movable into and out of engagement therewith comprising,in combination, an 'insulating housing ienclosing circuit interrupting means; a first terminal carried by said housing including a bushing secured thereto,'a contact member having "laterally extending contact means forengagingsaid normallyenergized terminal contact member and-including anarcuate portion at least partly overlying said bushing, and means;

detachably mounting. said arcuat'e' portion on said bushing; and a second terminalcarried by said housing and movable relative to saidfirst terminal havinga prongextending generally parallel to said laterally extending contact means for engagingisaid current carrying member and moving it out'of'engagement with said contact member on movement apart of said terminals.

8. In a circuit interrupter for'opening a high voltage circuit isolating device such' as a'disconnecting fuse, disconnecting switch or the like, normally carrying line cur rent and having-a normally energized terminal :eontact member and a current carrying member movable intoand out of engagement therewith comprising, in combination, an insulating housing enclosingcircuit interrupting means; a 'first terminal carried by 'said housing-including-a bushing secured thereto, a contact member for engaging said normally energized terminal contact member'including an arcuate portion at least partly-overlying saidbushing and having a pair of outwardly 'eXtending arms-with a bow shaped contact memberpivotally mounted therebetween, and means detachablytmountingsaid arc'uate portion on said bushing; and a second terminal carried by said housing and movable relative tosaid'first terminal'for engaging said current carrying member 'and'movingit out of engagement with said contactmemberon movement apart of said terminals."

9. The invention as set forth in claim 7 wherein the laterally extending contact memberincludes a contact arm extending radially'outwardly from'the arcuate portion.

10. In a'circuit interrupter foropening ahigh voltage circuit isolating device "such" as a disconnecting'fuse,dis

connecting switch or the like, normallyca'rrying line current andhaving a normally energized terminal contact member and a current carryingmember movable into and out of engagement therewith comprising, incombination, an insulating housing enclosing circuit interrupting means;

a first terminal carried by said'housing including a-"bush-- ing securedthereto; a: contact member having laterally extending contact means for engagingsaid normally 'ener-- gized terminal contact member and including acircular end cap overlying said bushing, and 'readily' detachable means holding said end cap; on: said bushing; andv 'a.sec-. 0nd terminal carried -by,-said housin'gzand movablewrela-1 ti'v'e to 'said first terminal havingvarprong extendinggenerally parallel to said laterallyjextending;contact means for :engagingtsaid current'carrying' member andamoving it out of engagement with saidtcontactmemberon movementapart of-said terminals:

11. Ina circuit':interrupter for openinga-high voltage circuit isolating ;device=-such as:a disconnecting fuse; dis-- connecting switch "or-the like; normally carrying vline icurrent and havingi-a -normally:energized terminal contact member and a current=carryingimexnbermovableinto and out of engagement :therewith'comprising, in combination,

an insulating-housingenclosingcircuit interrupting means; i a first terminal carriedubyj-said housing-including a bushing secured thereto, a contact member forengaging:saidznormally energized terminal contact member includinga circular end cap overlying :said-zbushing, key rneans interfitting b'etween said bushing-andnendcap tohold the latt'er ina'predetermined position therearound', and readily detachable m'eans holding-said end cap in position on'said bushingganda second terminal carried. by said housingv and movable relative to said first terminal forcngaging-v said current carrying? member-and moving it out of engagement'with said :contactmember on movement apart of'said terminals;--

12; In sacircuit interrupter'fcr opening a high voltage circuitisolating. device-rsuch as a disconnecting fuse, dis

connecting: switch or the'rlike, normally carrying line cur-- rent-andhaving a normallyenergized terminal contact member and a current carrying: member movable into and 1 out of engagement therewith: comprisinggin combination,

a tubular insu'latingr housingenclosing normally closed circuit interrupting means, andadapted to be'manipulated by alive line stick, said iinsulatingrzhousing :having' relatively movable apart spaced-"terminals adapted to beeconnected:

respectively to 'said membersfonetof said'iterminals car.- ried by such tubular 'insulati'ng'housing'includingian annu-:

lar bushing securedi thereto :andshavinguan annular groove near its outer 'end' and iairadially outwardly projecting flange Iat itsdnher end havingla transversely extending" keyway; a circularuend Icap"t'elescopediover Tsaid bushing and having an annular groove ?0verlyingwsaid flange with a radially inwardly'extendingikeyinterfitting with said.

keyway, a crescent shaped spring member frictionally held in said grooveand overlyinggthei outer end a of 'said end cap' to '-hold the. same ini position onsaidbushing, and

contact 'means carried by said end "cap forlengaging said normally energized:terminal-contact member; and the other terminal carryingfcontact means for-engaging said current carrying mem'berran'd moving it out of engagement with said contaetimernber:

13. The invention as set forth in claim 12 wherein the contact meansicomprises apair ofarms extending outwardly from the .end cap' withabow shaped contact member pivotallyimounted thereon.

14. Theinven tionrasiset forth in claim 12 whereinthe' contact means comprises a contact arm-extending radially outwardly from'z th'e end caps:

References Cited in the file of this patent UNITEDfiSTATES PATENTS Schneider" ..-.-Feb. 14, 1956

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