US2612542A - Electrical protective device - Google Patents

Description

G. F. LINCKS ELECTRICAL PROTECTIVE DEVICE Sept 30, 1952 '3 Sheefs-Sheet 1 Filed Sept. 20, 1949 INSULATION IHveTItOT: George E Lmcks;

His Attcrne Sept. 30, 1952 e. F. LINCKS 2,612,542

ELECTRICAL PROTECTIVE DEVICE Filed Sept. 20, 1949 3 Sheets-Sheet 2 Inventov: George E Lincks,

His Attovn e Sept. 30, 1952 G. F. LINCKS ELECTRICAL PROTECTIVE mavxczr 5 Sheets-Sheet 3 Filed Sept. 20, 1949 v v W m 8 RETURN LINE OAD

' Inventor: Gerge F Lincks,

Hi Attovn ey.

Patented Sept. 30, 1952 EEEGTRIGAL PROTECTIVE DEVICE George F. Lincks, Pittsfield, Massi, assignor to General Electric Company, a corporation. of

New York.

7 Application September 20, 1949, Serial No. 116,7 01

7 3 Claims. (Cl. 175-294) My invention relates to electrical protective devices; of; thafuselesscutout type: which; are: frequently employedtaisolate faulted. lines in electric. distribution systems; More particularly, my invention relates; to a type. of fuseless cutout which imposes; a. metallicshort circuit upon a. faulted. line to.- cause an associated circuit intermedium is satisfactory in some cases, in many applications the presence of a flaming arc. par:- ticularlyof the magnitude resulting froma. lowimp-edance short circuit, is objectionable or danegerous. It is desirable, therefore, to provide in a. fuselesscutout wherein a definite short circuit rupting device. to.- interrupt the: fault. priorto isolation; thereof by the fuselessp cutout.

In my copending' applicationSeria-lNo. Ill-1,702,. filedseptember 2Q, 1949 andassi'gnedtothe. same; assignee asthe. present invention. I. disclose; a. type of1fuseless. cutout in which an, arc-suppress.- ing device such as; an arc chuteis provided toaid; in extinguishing an arc, which formsin the switching. element; of; a. cutout. whenthe latter opens. in. responsezto. a. fault. condition. Should such. an arcfail to, be extinguished: byarc-suppressing: action. in. the; cutout, the arc is. transr ferredfromthe faultedline to. an auxiliary arcingelectrode preferablylocated in the arc chute and. connected to ground. or; another suitable; return patlr. Following transfer. of. the are, arc-suppressing action in the cutout; continues to. aid in extinguishment of. the are; 7

The; effect of. transferrinathe arc; is. to; shortcircuit the line through they arc. Such". shortcincuiting. action. results g nerally, in, case the: arc is not extinguished by; arc-suppressing: action in. the cutout, in; the opening: of: an associated. cir.- cult: breaker which interrupts thev line; and extinguishes. the. are. A. principal. feature of thedevice disclosed in the above-mentioned; copending' application is,. therefore, to effect,,whenever possible. interruption of? a. faulted line by action of the: cutout itself, rather than by opening; of a main reclosing: circuit breaker. to: reduce to a minimum. the number of momentary outages occurring: inbranch. circuits: in-which faults do not exist.

In many cases, itis. desirable toeffect. interruption of a. faulted line; by action. of a. cutout itselffin the manner: describedv In certain applications, however, a cutout. of: the type mentioned, even with; properly designed arc. chutes, may not be: depended upon to: interrupt a major: Portion of: faults: without: actually causing a. short circuit across the: line through. the transferred arc and requiring the reclosing' circuit;: breaker to interrupt the arcing current. Therefore; its applications. of? the latter type, it: is: frequently desirable tDl impose a definite short circuit on a line. to force operation of the circuit breaker, rather than attempttoclear'thefaultatthecutout.

' While the use: of an'arc as. a; shcrt-circuiting.

is desired a short-cirouiting arrangement throu h metallic contact or other means. to preventsformation of an are. H Y

An additional advantage of. short-circuiting a. line in response to a, fault to cause operationof a circuit breaking device is that the predetermined current causing. operation of a cutout devicemay be made appreciably lower and protectionmay be. provided for a relatively greater length of line; than would otherwise be the case; Ifa shortcircuiting action is not provided, the current, re.- quiredto cause opening of. the cutout must be atleast equal to the minimum. operating current. of. the reclosing circuit breakerto assureoperation of the breaker. Otherwise, circuit-interrupting requirements for which thecutout is not designed,

may be imposed thereupon. p

It is the principal object of my inventionv to provide a new and improved fuseless cutout to short-circuit a linethrougha suitable returnpath in response. to a fault condition and to isolate. the faulted line following interruption of the shortcircuit by an associated circuit breaking device.

In accordance. with, a. preferred. embodiment of, my invention, I. provide a fuseless cutout; of. the open type; in which a current-responsive element such as a thermostatic device effects closing of a switching mechanism in responseto a. fault condition beyond. the cutout to short-circuit the faulted. line through. a suitable return path such as ground. Following the short-circuiting;opera tion, an associated. circuit breaking device is caused. to. open, therebyinterrupting the fault. A

second current-responsive element, preferably an electromagnetic device, is. arranged-to: prevent opening of the main switch mechanism of. the cutout. initially in response. to the. fault, but; to release andv cause opening of the main switch mechanism and isolation of. the faulted. linefollowinginterruption. of the short-circuit. current by the circuit breaking, device. According to another preferred embodiment, I. provide; an en.- closed cutout device in which a single current: responsive element, preferably an electromagnetic-device,v is arranged. to effect in sequence the short-circuiting and circuit, opening" functions previously described. v.

For abetter-understanding'of my inventiom at tention; is now directed to the followinggdescrlm tain elements} shown in Fig. 1; Fig. 2 is a front,

elevational view of the device shown in Fig. 1; Fig. 4 is a side elevational view, partially sectionalized, of an enclosed cutout device embody ing certain features of my invention; and Figsg 3 and 5 are schematic diagrams showing the electrical relationship of certain elementsof the devices shown in Figs. 1 and 4, respectively.

Referring now to Figs. 1, 1a, lb and 2, there is shown a fuseless cutout of the open type for use in a line of an electrical distribution system.

Cutout I is provided with an insulating member 2 on which are mounted an incoming or line inorganic material, such as porcelain or glass,

may be of conventional design and is of a size suitable for the line voltage-with which cutout I is -to-be employed. Insulator 2, which forms the principal supporting member for the elements of cutout-I,- is provided with a hanger 5 which is employed in mounting cutout I to an external supporting structure (not shown). Hanger 5 is a metallic strap clamped about the approximate center of insulator 2 by a screw 5 and nut I. Hanger 5 also serves as an auxiliary terminal for cutout I-to which suitable return path is connected, as will hereinafter be described.

"Terminal 3is a threaded lug fastened as by cementing in the upper end of insulator 2, while terminal=4 is a threaded lug similarly fastened in the lower end of insulator 2. A pair of switch mechanisms; provided for cutout I may be conveni e ntly designated as a main switching mechanism 8 and an auxiliary switching mechanism 9. Main switching mechanism 8 comprises principally a contact I0, a'switch'arm I I and a flipper arm I2. 7

Contact; I 0 and flipper arm I2, which are shown in detail in Figs. 1a and lb, respectively, may conveniently be formed of a wire having a relatively high-degree of elasticity. I Contact Ill, which is generally symmetrical about its center line, may beiormed from a single length of wire doubled to' provide a mounting loop I3 at one end of contact II) for securing tolug 3 by the use of a pair of suitable washers I4 and a nut I5. The opposite portions of wire leading from loop I3 are brought together and secured by brazing or otherwise to form a straight portion I6 at the approximate center of contact I0.

The free end of contact I0 is provided with an eyelet portion I'I arranged to engage arm II, and a pair of catch portions I8 arranged to engage an auxiliary switch arm, as will be described. Eyelet I1 is formed by providing a pair of outwardly projecting half-loops in the wire forming contact I0. Since the opposite portions of contact "III are secured together at center portion I6 and contact I0 is formed of a spring material, eyelet I! is normally maintained in a substantially closed position. However, opposite sides of eyelet I! at the end thereof away from center portion I6 may be spread apart by opposing the spring action tending to hold eyelet I! closed, as by forcing switch arm II into engagement with contact IO-in eyelet I1. Catch portions I8 are fo'rmed incontactIIl by providing downwardly projecting half-loops in the ends of the wire forming contact I0.

Flipper arm I2 may conveniently be formed of a single length of wire doubled to provide a mounting p I9 for securing flipper arm I2 in fixed relation to insulator 2 at lug 4. Flipper arm I2 is electrically insulated from lug 4 by an insulating spacer 20 and an'insulatingwasher 20'. Washer 20, loop I9, 'spacer"'20 and a supporting member 2|, to be described hereinafter, are clamped to insulator 2 by the use of a nut 22 threadedly engaged with lug 4. Flipper arm I2 is symmetrical about its center line and is provided with one'or-Y'more spring loops 23 wound therein in the vicinity of loop I9. The lengths of wire extending'from loops 23 are joined by brazing or otherwise to form a straight portion 24 which extends approximately one-half of the length of flipper arm I2. A pair of bands 24' provide additional fastening action at the ends of straight portion'24.

Beyond the end of straight portion, the free ends of the doubled wireforming arm I2 are formed intoapair of loops 24" spaced apart sumciently to receive therebetween a similar loop 25 formed in the lower end of switch arm II. In otherwords, flipper armil2- and switch armII arejoined in a-hinged relation by interlocking loops 24" and 25 with a screw. 26 and nut 21. A biasing spring'28 is attached to-arms II and I2 at thejunction: thereof. Spring 28' has a: tendency to bias arm II in a clockwise direction with respect to-arm I2. Spring loops-23 havea tendency to bias switch'arm I2 in a clockwisedirection about the center of loops 23".:-

- I A pair of latch mechanisms 29 and 30 are pro-.. vided to maintain flipper arm I2 .and switch arm II in predetermined positions. iLatch mcchae nisms 29 and 30 are supported atthe free end of supporting member 2I', which. may conven-.. iently take the form of a rigid plate of an insu-. lating material. Latch mechanism 29 comprises a current-responsive element, preferably a.bi-, metallic device 3I, and a latch 32. Latch mechanism 30 comprises a second current-responsive element, preferably an electromagnetlcdevice I33, and a second latch 34. 1 1 Latches32 and 34 are supported by a common supporting member 35 which is represented as a generally U-shaped member fastened to support 2I by one or more screws 36. Latches 32.. and 34 are supportedby'a pairof pins 31 loosely fitted to permit latches 32 and 34 to pivot freely thereabout. Support 35 ispositioned-so as to be substantially in a plane with straight portion. of flipper arm I2. Thus, as arm I2 is rotated in a counterclockwise direction against the biasing action of spring loops'23, straight portion 24 may be positioned within'support 35 where engagement is made between straight portion 24=a'nd latches 32 and 34. Theinside width of support 35 and the projection of latches 32 and 34 in support 35 are so arranged that arm I2 may be maintained in a latched position by either latch 32 or 34, provided the latches are maintained in latching positions-through external forces acting thereupon. It willbe noted that latch 34 is longer than latch 32'; 'I'hus, flipper.arm-I2 is maintained in a higher or more counterclock-v wise position by latch 32 than-by latch 34. Thermostatic element 3| and. electromagnetic element 33 are employed .to'control thelatching actions. of latches 32 ...and. .34, respectively. Thermostatic element .3 I. comprises amounting bracket 38 fastenedto support 2| by one ormore screws 39. A pair of: bimetallic strips: 49:: and 411 are. fastened. tor a block: 42: of insulating; material which, inaturn, is secured to support-38 byoneor, more suitable. screws 43.. Strips 40 and 41' are" insulated from each other: at the upper ends thereof but: are electricallyjoined. by a. generallyu-shaped. bracket 44, secured to thelower end thereoftby brazing. or otherwise. A screw 45, having an insulating head 46, is threadedly engaged with bracket 44.

Head 46 is arranged. to engage latch 32. relatively low temperatures; such as normal. at:- mospheric temperatures; bimetallic; strips 49 and 41- are; in agenerally flat. condition and, screw 45 isadapted. to maintain latch 32 in. its latched.

position. Heating of bimetallic-strips 49 and.4-i

causes bending thereof inv a clockwise direction about support 42. As: suchbending occurs,.screwhead 46 is caused to move away from latch 32, leaving; latch 32 free to pivot outwardly: withzrexspect tosupport 35, thereby releasing, straight portion 24 of arm I2 from further latching action by latch 32.

Electromagnetic device 33 may be of conventional solenoid design and is shown as com.- prising; principally a plunger. or armature, 41, a frame 48 and a winding 49. Plunger 41 and frame 43- are formed of a magnetic material, such as iron. Electromagnetic device 33 is mounted and adjusted in such a manner that when a. relatively high. current. flows. through winding 49, creating a substantial magnetic field in device 33, armature or plunger 41 is caused to engage ,latch 34 andmaintain it in its latching position. However, should the current through winding49 be-interrupted, thereby reducing the magnetic fleld to a negligiblevalue, then plunger 41 ceases to exert a force on latch 34, which is then free to move away from its latching position to permit flipper'arm- I2 to be unlatched.

The sequence of. latching and, unlatching' of flipper, arm Ills, as follows: When arm [2 is in. its freeposition, it is biasedby spring loop- 23 to aclockwiseposition shown inFig. 1 by abrokenline view 12' of arm. l2. As arm I2 is rotated in.a counterclockwise direction by an operator, straightportion 24 enters support, 35 at the opening thereof where it may be: guided by an angu larly disposed extremity 59. of support 35. Engagement is first made, withthe. lower: on cam- 1ike;surfaceof.latch; 34,.which causes latch 34 to be: forced. outwardly. to permit straight portion. 24-v to' pass thereby. Similarly, as straight portion 24 engages the lower or cam-like surface. of latch 32, latch 32. is forced outwardly against" the spring action of bimetallic strips 40 and 4 l to permit straight portion 24 to pass by latch 32. Thereafter, the spring action mentioned forces latch 32 inwardly with respect to support 35, thereby effectively'maintaining flipper arm 12 in its latched position, as shown in Figs; 1 and 2. Iflatch 321s now released, arm 12 is biased downwardly and if no force is exerted by plunger 41 on latch 34, arm- 12 is free to return to unlatched position. However, if a force is exerted inwardly on latch 34-; arml2 is engaged thereby, following release by -latch 32, and arm I2 is maintained in a lower latched position, indicated in Fig. 1 by abroken-line view 12'. The significance of having two latched positions of flipper arm [2' in addition to a free position thereof will become more apparent as the operation of switching mechanismsB "and 9 is described. Attentionis next 'directed to the structure of auxiliary: switching mechanism 9, which com prises principally" ascontact 511}: a switch: arm 52 and a. restraining: arm. 53. Contact 5:1 isv formed ofash'ort length. of wire secured by a screwidito hanger 5. Contact 51' is mounted in the principal. plane of cutout I and is normal thereto; Switch arm. 52 is supported by: an. insulating membern55 secured in. fixed. relation. to switch arm-1 H by clamping or otherwise. 5'2" pivotally. mounted insupp'ort 5.5; and: i arrange'd toxpivot: with respect to arm l:l...' 1'

The motion and. positions of: arm; 52i are-closely associated withzthe" latche'dzpositions: of; arm. I2- andwill beconsidered with respectitheretoai It; is first assumed that: arm. I2 is inlitszupperlatcheds or normal operating position, and: thatifarmi H2 is engaged with eyelet H of contact II as shown;

in Fig.1. Under this conditiomarm 52- does not: engage. contact'5i, but ismaintained in ansopen position by engagement of restraining arm- 53-with. catch portion l8 of contact 10.. Restraining arm 53%.andswitch arm 52mayconveniently=be formed of a single. piece of wire or rod. suitablybentto;

form switch arm 52,,a bearingportion 56Jmounted in. insulator 55,, restraining arm 53,,and .an:en-1 gaging, portion 53 formed at. the end of arm; 53 andarranged to engagecatch 18:. v.A biasjspring 51 is provided between arm 52 and support;,-55,-, tending to rotate arms 52 and 53- ina. clockwise direction with respect to arm, i I.

If latch 32 is released, vpermittingflipperarrrr i2'to: move to its lower latched position. 12 and beimain-tained-thereat by latch. 34; then-.arm this, dropp'ed'to a lower position and engagingportion 5310f, restraining, arm. 53 nov longer. engages catchesla. In other. words,.under thisconditionarm- 52 is freeto pivot and is biasedin a clockwise.- direction into engagement withcontact 5 l by; ac; tionof spring 51. The length of arm H is such that upper extremity 58 thereofis maintained in engagement with contact. Iii in the lowerlatched position ofarm 12-. -However, upon release. of. latch 34, flipper arm 12 is permitted tomove to its free position I2, thereby causingarm ll to,be freed from. engagement with contactlil and to drop away therefrom. The. motion of arm..l I is further aided by biasing spring.28.- .A s arm ll is caused-to drop, arm 52 is likewise disengaged from contact 51 and underthis condition switch .mech' anisms B and 9 are botheffectively opened. I

To; provide the desired conducting paths through cutout device. I a lead. 59 isv connected fromv terminal 4, through the use of a suitable conducting washer ,69 interposed between: support 21 and insulator2, to the upper end of bi.-v metallic strip 49. A second lead 61' i connected between the upper end of bimetallic: strip and one. end of. winding 49, which. also isconnected by theuse of aflexible lead 62 toswitchiarm 52. .=The other endof. winding 49 is. connectedtoflipper arm.l2. x Two principal conducting paths are provided: through cutout l. The first ornormal' path: is from terminal. 3 through contact" 10, switch. arm H, flipper arml2, magnetic winding 49, lead- 6|, bimetallic strips 41 and 40, and lead59 toterminal l. A second or short-circuiting path exists following release of arm 52 and engagement thereof with contact 51 The second path is fromtermina-l 3 through contact Ill, switch' arm ll, flipper arm l2, magnetic winding 49, flexible lead 62,-sw-itch arm 52, and contact 51 to auxili'aryterminalI5-J I I The electrical relationship ofelement's men tioned and the conducting paths therethrougli areashown schematically in 3, *in-whicmut:

out! is shownwithin a closed broken line. Main switching mechanism 8 is shown in a closed position in Fig. 3, while auxiliary switching mechanism 9 is shown in an open position. Switches 8 ,and 9 are shown, therefore, in their normal operating positions, indicating the normal conducting path through device'l from terminal 3 to terminal 4. Following release of flipper arm 12V to its lower latched position, switch 9 is closed by release of arm 52 and conducting paths exist through device I from terminal 3 to terminal 4 andfrom terminal 3 to terminal 5.

In the operation of the device described, it is assumed that cutout device I is inserted in a line in an electrical distribution system in combination with a reclosing circuit interrupter which is not shown. The incoming line is connected to terminal 3. The outgoing or load line is connected to terminal 4 and terminal is connected to a suitable return path, such as ground. For normal operation, flipper arm 12 is placed in its upper latched position. Arm H is placed in engagement with contact 10 in eyelet I1 and restraining portion 53' of arm 52 is placed in engagement with catch l8. Thus, the normal load current flows through switch 8 and through thermostatic element 3 I.

If -a fault condition occurs beyond device i causing an abnormal current to flow through thermostatic element 31, abnormal heating occurs therein. Under this condition, bimetallic strips 40 and 4| bendoutwardly, releasing latch 32 and causing flipper arm 12 to drop to its lower latched position 12". The fault current through winding 49 causes plunger 41 to lock latch 34 to maintain flipper arm [2 in its lower latched position l2". Arm II is likewise dropped by an amount sufficient to release arm 52 from catch [8, permitting arm 52 to bebiased into engagement with contact 5| by spring 51. Under this condition, a low-impedance short-circuit is created between terminals 3 and 5 or between the line and ground. The short-circuit current flows through switch 8, winding 49 of solenoid 33, flexible lead 62 and switch 9. As long'as this relatively high current continues to fiow through winding 49, it causes plunger 41 to continue to lock latch 34 to maintain flipper arm l2 in its lower latched position [2. Following the short-circuiting of the incoming line and the establishment of a relatively high short-circuit current, the external circuit interrupter is caused to open, thereby interrupting the current through device I and particularly through winding 49. Plunger 41, therefore, no longer exerts a force on latch 34 and flipper arm I2 is released, thereby to be biased to its free position [2 by spring loops 23. As arm 12 moves togit' free position, arm II is disengaged from contact 10 and moving clockwise under bias of spring 28 disengages arm 52 from contact 5|, removing the short-circuit. Also, the faulted line is isolated from the distribution system and the reclosing circuit interrupter may re-establish service on the remainder of the distribution system. Following the sequence of operation described, cutout i is in open position and may be reclosed by an operator, as previously described, following removal of the fault condition in the outgoing line.

By the use of a cutout device constructed in accordance with my invention, it is possible to impose a positive metallic short circuit on a line in response ,to a fault condition therein withoutan accompanying flaming are. Another feature: of

, fit in tubular portion 86' 8. my invention, as herein-embodied, is the 18018. tion of the faulted line fromground following opening of the cutout. faulted line is highly desirable since, in many distribution systems in common use, grounding of a. faulted line may cause undesired grounding/of other points in the system following restoration of service by reclosing action of the circuit interrupter.

Referring now to Fig. 4, there is hown, partially sectionalized, a fuseless cutout 15 of the enclosed type embodying certain features of my invention. Cutout'15 is provided with a housing 16, preferably formedof an inorganic material such as porcelain. Housing 16 forms the principal supporting member for the elements of device 15 and is arranged to form the top. back and side surfaces of the cutout. Cutout 15 i supported on an external supporting structure (not shown) by a hanger 11 fastened to a back surface' of housing 16 by'cementing or otherwise.

The operating elements of cutout i are for the most part supported on a door member 18, formed of an insulating material such asmolded compound. The operating elements and door member 18 form a door assembly 19 which is hinged with respect to housing 18 at a pivot 80, which may be a pin fixed to a bracket 8|, the latter being fastened as by cementing in the lower portion of housing 16. Door assembly 19 comprises principally, in addition to door member 18, a metallic supportin member 82, an electromagnetic device 83, a slidable rod 84, a toggle member 85, and a mounting bracket 86. Supporting member 82 is secured in fixed relation to door 18 by the use of a plurality of threaded studs 81 fastened as by inserts molded in member 18, and a plurality. of nuts 88.

Bracket 86 is secured in fixed relation as by welding to supportingmember 82. One function of bracket 88 is to form a support for slidable rod 84. Rod 84 and an insulative sleeve 89 are concentrically positioned in a tubular portion 86 of bracket 86. Sleeve 89 may be a relatively tight of bracket 86, but rod 84 is slidably supported in sleeve 89. Sleeve 89 is provided with a lip portion 98 at the upper end thereof to secure a definite position of sleeve 89 with respect to bracket 86.

Electromagnetic element 83 comprises a frame member 9| formed of magnetic material, such as iron, and a winding 92 wound thereon. Frame 91 is secured in fixed relation, as by welding, to bracket 86 or support 82, whichever is more convenient. Toggle member is pivotally mounted with respect to bracket 86 by the use of a pin 93 and is insulated from bracket 86 by the use of an insulating sleeve 94. Toggle member 85 is provided with a hook portion 95 which, in combination with pin 88, serves as a hinge for door assembly 19. Toggle member 85 extends beyond pivot point 93 is the vicinity of electromagnetic element 83 and this portion of member 85 is formed of a magnetic material, suchas iron, so that it constitutes an armature responsive to magnetic forces established in magnetic element 83.

It will be seen from the description thus far that the elements mentioned as forming door assembly 19 are mounted on support 18 and the entire assembly is arranged to pivot about pin 88 and be supported thereby through hook 85. A latch element 98 is provided at the free extremity of bracket 88 and is arranged to engage a catch element 91 fixed as by cementing in housing 16. The cooperating combination of Such isolation of the latch :96 and :catch :91 serves two principal functionsrj-The first 'is to form the elements of a main switch mechanism of cutout 15, and the second is .to serve asa latch to maintain door assembly 19 in: a closed position.

Catch 9?! serves as an incoming or line terminal for cutout 15. -In normal operation, latch 96 is "arranged to be maintained in latching engagementwith catch 91 to permit conduction of cur- :renttherebetween and to maintain door assembly 19 in closed position. An outgoing or load terminal for cutout 15 is provided by a lug 98 formed of a conducting material and secured in ifixed relation with respect to housing I6 by the use of a threaded stud '99 cemented therein and a .nut ltlil." Lug 9B is arranged to make sliding electrical-engagement with'toggle member 85 on iacontact portion of lug 88', indicated by numeral Slidable rod 84 forms one element of an auxiljiary switch mechanism, the function whereof is to short-circuit the incoming lin to a suitable return path, such as ground, through an auxiliary terminal. Such a terminal is provided by an angular bracket I02 secured in fixed relation to housing i6 by the use of a threaded stud I03 cemented therein and a nut HM. Contact [02 isof sufficient length to permit engagement therewith of slidable rod84. Sliolable rod 84 is pro- :vided on the upper portion thereof with a fixed collar 84' arranged to be engaged by the upper extremity of a helical spring I05, the lower extremity. of which engages lip 9B of insulating sleeve 8:9. The function of spring I05 is to force rcdii i into engagement with contact Hi2. Brack- Biiand bracket 86, tending to rotate. the assembly of elements mounted in fixed relation with respect to bracket 86 and support 82 in a counterclockwise direction with respect to toggle 85 about pivot-point 93. Such rotation is restricted by engagement of latch 161 with reduced portion [its or rod 84. A latch 'l laps/mm; mounted by a'pinll l in frame Si, is provided to enga e the outer extremity or armature portion of toggle membertii inthe vicinity of electromagnet 83. Latch H3 is provided with a hook-shaped end I arranged to engage a notched-out portion 1 l6 of toggle member 85. A biasing spring H1 is {provided between frame ii I and latch l l3, tending to rotate the latter in a counterclockwise direction about pin H4.

' There are two principal conducting paths throughdevice 15. One end of winding 92 is made electrically common with bracket 36 and frame "9! by the use of a screw 1 Hi. The other end of Q concluctingpath through device 15 is from the incoming terminal formed by catch 9"! through. latch 96, brackettd, winding '92, and toggle member=85to theToutgoin'g terminal formed by mg 098. The short circuiting"path through device 15 is. from incomingterminal 9! through latch 96,;bracket 18:8 and winding :92 to toggle member tion of toggle member 5-85 is in i1 0 and thence through flexible lead I2 I; and slidable-rod '8 to the auxiliary terminal formed by contact 192. The electrical relationship of the principal elements forming the conducting paths throughdevice I5 is shownschematically in Fig.5, in-which device I5; is shown within a closed broken :line. In Fig.5, the main conducting path through-device 15 is shown between terminals 91 and 98 and the short-circuiting path between terminals 9 1 and 102. It will be noted that in both cases the entire line current flows through winding 49-21 for electromagnet 83. 1 In considering the operation'of device 1531i: E15 assumed that device .15 is connected in .ailineiof an electrical distribution circuitv in combination with areclosing circuit interrupter, asin ithecase of the first embodiment described. The incoming line is connected to terminal 91,, the outgoing or load line is connected to terminal 98,, and terminal 102 is connected to suitable return path,

such as ground. 1 I

For normal operation, cutout device 15 isias represented in Fig. 4. Door assembly 19 :18 maintained in its closed position by latching. engagement between latch'96 and catch 91. 'Slidabl'emod B4 is maintained in its latched i-DOSltlOIlbY BIlgagement of latch Iii-l with redu'cedportion 1108. In other. words, the main switching mechanism of cutout 15 formed by latch .96 and catch '91: -.is

closed, thereby completing the conducting :path

from terminal 91 to terminal 98. The auxiliary switch mechanism formed by slidable rod Bland bracket I02 is in an open position and, accordingly, the conducting path between terminalsfl and 102 through device 154s incomplete, The biasing action of spring Ht serves to maintain latch mi in engagement with reduced-portion I08. Latch H5 is engaged with notched outzpdn tion I [6 of toggle member 85 andiis prevented from being biased away from :notchf I Hi 'by'interference therewith. I

If a fault condition'o'ccurs in the'loa'd line'l'ea'd ing fom terminal t8 of cutout 15, the current flowing through the normal conducting path thereof and particularlythrough winding 92' i's substantially .increased in magnitude.- Whenra predetermined magnitude is reached, "as determined by the magnetic air gap between .friame 91 and the armature portion of toggle member 85, and the biasing force of spring I H],- the magnetic force exerted on toggle member 85 causes rotation thereof :in a counterclockwise direction. Such rotation continues until the armature p'ortouching engagement With frame'QI. 1

The lengthof latch l'ill :is'such'that upon rotation'of toggle member 85, latch i0! is disengaged from reduced portion I08 of rod 84. Rod 84 1's thereby released from its latched position and is biased by action of spring I05 into touching engagement with bracket )2, as indicatedinl ig. 4 by a broken-line view of rod-84. ,As toggle member 85 is rotated by magnetic action, latch I ['3 is freed from engagement with notch :I Hi and ts biased-into its unlatched position, indicated in Fig. 4 by a broken-line view of latch I [3. In this position, latch H 3 no longer engages togglemember 85.

Upon engagement of rod 84 with bracket 102, the short-circui-ting path through cutout 15 is completed, thereby imposing a relatively=low-im current in the incoming line over its previous value and causes opening of an associated circuit interrupting device, such as an automatic reclosing circuit breaker (not shown).

Opening of an associated circuit interrupting device causes the current through cutout I5, and particularly through winding 92 to be reduced to -zero.. Accordingly, magnetic force ceases to be exerted by magnet 83 on toggle member 85. Toggle member 85, thus, is permitted to drop sufii- 'ciently to cause unlatching to occur between latch96 and catch 91. When-such unlatching action occurs, door assembly 19 is no longer -latched in its closed position and is permitted to drop open around pivot 80 to a position shown in Fig. 4 by a partial broken-line view of door 19. *When' door 19 drops open, both the main and auxiliary switch elements of cutout are opened :thereby interrupting the main and short-circuit- -ing conducting paths through device 15.

The faulted load line, which is connected to terminal 98 is isolated from ground following opening of door 19, as in the case of the first embodiment described.

Following clearing of the fault condition in the load line device 15 may be reset or again placed in condition for normal operation by an operator. Such resetting includes returning rod 84 and toggle member 85 to their latched positions, as shown in Fig. 4, and then returning door assembly 19 to. its closed position by pivoting it about hinge pin 80 and effecting latching engagement between latch 96 and catch 91. The latter step also effects closing of themain conducting path through device 15. A conventional eyelet I23 may be provided in door support 78 to aid in closing door assembly 19 by the use of an operating stick.

It will be noted that in the second embodiment of my invention herein described a fuseless cutout is provided wherein only a single currentresponsive element is employed. Such an element is made to cause a metallic short-circuit to be imposed on a distribution circuit in response to a fault condition therein and subsequently to cause opening of the cutout and isolation of the faulted line from ground, in response to current companying arcing conditions at the cutout device. By providing a short-circuit at a cutout device to force operation of an associated circuit interrupting device, a relatively low predetermined current may be employed to cause operation of the cutout device, thereby providing a relatively higher degree of protection that would otherwise be the case.

- While I have shown and described certain preferred embodiments of my invention, it will be understood that my invention may well take other forms and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention. 1

What I claim as new and desire to secure by connecting apparatus to be protected and supplied with current to a line leading from a cir- :cuit interrupter responsive to the flow of abnormal current in said line, comprising main switching means connected in series with said line and arranged to be closed in normal opera tion of said device, auxiliary switching means comprising a stationary contact electrically connected to an auxiliary return path for said current and a movable contact electrically connected to said line and engageable with said stationary contact, said contacts being unengaged in normal operation of said device, means responsive to a predetermined current flowing through said main switching means to cause engagement of said movable contact with said stationary contact and interconnection of said line and said return path to cause abnormal current to flow in said line, a magnetic winding connected electrically in series with said line and an armature for said winding, said armature being responsive to flow of said abnormal current to maintain said auxiliary switching means in said contact engaging position and thereafter to open said main and disengage said auxiliary switching means in response to subsequent interruption of said abnormal current.

2. An electrical protective device for use in connecting apparatus to be protected and supplied with current to a line leading from a circuit interrupter responsive to the flow of abnormal current in said line, comprising main switching means connected in series with said line and arranged to be closed in normal operation of said device, auxiliary switching means comprising a stationary contact electrically connected to an auxiliary return path for said current and a movable contact electrically connected to said line and engageable with said stationary contact, said contacts being unengaged in normal operation of said device, means including a thermostatic element responsive to a predetermined current flowing through said main switching means to cause engagement of said movable contact with said stationary contact and interconnection of said line and said return path to cause abnormal current to flow in said line, a latch movable to a holding position to maintain said auxiliary switching means in said contact engaging position and movable to a released position to permit disengagement of said auxiliary switching means, a magnetic winding connected electrically in series with said line and an armature for said winding engageable with said latch in response to flow of said abnormal current to maintain said latch in said holding position and said auxiliary switching means in said contact engaging position, said armature being responsive to subsequent interruption of said abnormal current to permit release of said latch and effect opening of said main and disengagement of said auxiliary switching means.

3. An electrical protective device for use in connecting apparatus to be protected and supplied with current to a line leading from a circuit interrupter responsive to the flow of abnormal current in said line, comprising main switching means connected in series with said line and arranged to be closed in normal operation of said device, auxiliary switching means comprising a stationary contact electrically connected to an auxiliary return path for said current and a movable contact electrically connected to said line and engageable with said stationary contact, said contacts being unengaged in normal operation of said device, and current responsive means including a magnetic winding and an armature therefor responsive to a predetermined current flowing therethrcugh to effect engagement of said movable contact with said stationary contact and interconnection of said line and said return path to cause abnormal current to flow in said line, said armature being responsive to said abnormal current to maintain said auxiliary switching means in said contact engaging position and responsive to subsequent interruption of said abnormal current to thereafter cause opening of said main and disengagement of said auxiliary switching means.

GEORGE F. LINCKS.

14 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 689,353 Cheatham Dec. 17, 1901 1,105,392 Wright July 28, 1914 2,334,571 Matthews Nov. 16, 1943 2,349,609 Brown et al. May 23, 1944 2,387,372 Watkins Oct. 23, 1945 2,472,657 Gay June 7, 1949 2,502,179 Smith Mar. 28, 1950 2,545,660 Graybill Mar. 20, 1951

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