US2532258A - Electric circuit interrupter - Google Patents

Description

Nov. 28, 1950 G. F. LINCKS ELECTRIC CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Filed Feb. 16, 1944 Inventor: George F. Lincks,

His Attovney.

Patented Nov. 28, 1950 ELECTRIC CIRCUIT IN TERRUPTER George F. Lincks, Pittsfield, Mass, assignor to General Electric Company, a corporation of New York Application February 16, 1944, Serial No. 522,584

3 Claims. 1

My invention relates to electric circuit interrupters, and more particularly to such circuit interrupters which are adapted to be used in place of the conventional fuse cutout devices. Specifically my invention relates to a so-called fuseless cutout of the open type which may be either of the single element or reclosing type.

Fuse cutout devices have been used to a large extent in the protection of high tension electric distribution circuits. Devices of this kind in general heretofore have comprised replaceable fusible means usually located in close proximity to the high tension conductors. An abnormal electrical condition occurring on a circuit protected by a fuse cutout will destroy the fuse link and hence require replacement thereof. In modern practice on distribution systems several of these overcurrent protective cutout devices are connected in series thus demanding accuracy in order for proper correlation 'of such devices and so that each device performs its predetermined function. The need for renewal of the fuse link introduces the human element which, especially in a time of stress which is the time when fuse links blow, is apt to err by installing a fuse link of incorrect rating because the correct rating is not available. Also, although recent experimentation and research have reduced the cost of replaceable fusible elements, nevertheless such cost is still appreciable and it would be desirable to provide a fuseless cutout which would automatically interrupt the circuit under abnormal electrical conditions and yet wherein it is unnecessary to replace any fuse link after the protective operation of such cutouts, as is necessary with the fuse cutouts of the prior art. Also with reclosing fuse cutouts the clearing of temporary faults without service interruption is limited to the number of fuse links available for successive operation or to the abilityof the operator to discover and to renew blown fuse links before an outage occurs. With the reclosing fuseless cutout it is unnecessary to manually replace any fuse links so that an unlimited number of temporary faults can be cleared without any attention by the operator.

My invention is related to the inventions disclosed and claimed in the copending applications of Sidney R. Smith, Jr., Serial No. 334,629, filed May 11, 1940, now Patent No. 2,424,126, July 15, 1947, and Serial No. 459,791, filed September 26, 1942, now Reissue Patent No. 22,744, April 9, 1946, both assigned to the same assignee as the present application, as well as to my prior copending application, Serial No. 388,864, filed April l6,

2 1941, now Patent No. 2,379,729, July 3, 1945, and also assigned to the same assignee as the present application.

It is an object of my invention, therefore, to provide a new and improved electric circuit interrupter adapted to replace the fuse cutouts of the prior art.

It is another object of my invention to provide a new and improved fuseless cutout which is simple and compact, economical in construction and which may be substituted for conventional prior art fuse cutouts.

It is another object of my invention to provide a new and improved fuseless cutout of the reclosing type, as disclosed and claimed in my copending divisional application, Serial No. 536,872, May 23, 1944, now Patent No. 2,472,625, June 7, 1949.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying draw ings in which Fig. l is a side View, partly in section, of a fuseless cutout embodying my invention with the contacts in the closed current carrying position; Fig. 2 is an enlarged view with certain portions omitted, partly in section, looking in the direction of the line 22 of Fig. 1; Fig. 3 is a partial view of a fuseless cutout similar to the one disclosed in Fig. 1, illustrating a modification of my invention; Fig. 4 is a view similar to Fig. 2, taken along the line 4-4 of Fig. 3; Fig. 5 is a view similar to Fig. 1 of a fuseless cutout of the reclosing type embodying my invention, and Fig. 6 is a view similar to Fig. 2 taken along line G-6 of Fig. 5.

Referring now to Figs. 1 and 2 of the drawings, I have illustrated my invention in connection with an insulating support ll! of porcelain or other similar insulating material of a size and shape used in connection with the fuse cutouts of the prior art, such as is disclosed for example, in United States Letters Patent No. 2,354,907, Bennett et a1., granted August 1, 1944, and assigned to the same assignee as the present application. Insulating support, or insulator l0 may be suitably supported from a pole carrying the transmission line (not shown) as by a supporting strap, mounting bracket, or hanger construction generally indicated at H, which is adapted to surround a central portion of reduced diameter I2 of the'insulator I0. Supported from the lower end of insulator IE! is the lower terminal contact assembly i3, to be described in greater detail hereinafter, which includes a movable contact i=3. Cooperating with movable contact [4 is the stationary contact I5. In order to provide a satisfactory contact wipe the contact I4 is provided with a portion I4 biased toward contact I5 by spring It. Contacts I4 and I5 comprise the'relatively movable contacts of the circuit interrupter of my invention and contact I5 is illustrated as being mechanically supported from the upper end of insulator II] by means of supporting arm I'i. Contact I5 is furthermore-electrically connected to line terminal I8 :to which-anzexternal electric circuit such as conductor I9 may be connected.

It should be understood that insofar as myinvention is concerned the relatively movablecontacts I4 and I5 may be embodied in any suitable type of circuit breaker. As illustrated in Fig. 1, these contacts are embodied in an expulsion type circuit interrupter and contact I5 is mounted at the upper end of a tube of insulating material which is suitably supported from arm I1 either by a permanent or readily removable means. Tube 28 is preferably at least lined with amaterial from which an arc extinguishing gas is evolved when subjected to the heat-of an electric arc. Movable contact I4 is furthermore constructed in the form of a rod and reciprocally movable within insulating tube 20. Upon relative separation of contacts I4'and I5 by downward movement of rod contact I4 an arc is drawn in insulating tube 20. The heat of this are causes gas to be evolved from the gas'evolving surface within tube 20 to cause rapid extinction of the are drawn and expulsion of the arc gases from the lower end of tube2ll, which is open. 7

The lower terminal contact assembly 1300mprises a U-shaped support of conducting material 2|, which is suitably fastened'toinsulator Iii, as indicated at 2 I. Electrically and mechanically connected to U-shaped conducting support 2| is a resilient contact supporting arm 22. This resilient contact supporting .arm extends outwardly from insulator II! in the same direction as support I? and terminates in an upwardly extending portion 23 upon which rod contact I4 is supported. Resilient arm 22 might secure its resilience from a separate biasing means or may be formed of heavy wire preferably with a coiled portion 24 adjacent the supported end thereof to increase the resiliency and furthermore to constantly bias the contact I4 in a downward direction. Preferably resilient arm 22 is provided with a loop or eye 25 adjacent the contact supporting end thereof so as to be engageable by a switch stick for closing the circuit breaker, as will be described in greater detail hereinafter.

By virtue of the resilience of arm 22, means must be provided to latch the arm in the-closed circuit position since otherwise contacts I4 and IE will not remain in engagement. Supported from one end of the U-shaped conducting support 2! there is provided 'a latching means including thestationary backing member 26 which prevents the resilient member 22 from moving out-of its normally latched position with respect to latch 21. Latch 21 is pivotally mounted "to one end of U-shaped conducting support '2I as indicated at 28 and is biasedin a counter-clockwise direction as viewed in Fig. 2 by spring means '2 9. The freeendof'latchingmember 21 indicated at 21 and the free end of backing member 26 indicated at 26 are constructed in a diverging manner to insure movement of resilient arm 22 into latching position when moved upwardly by means of a maintenance tool, or the like, engaging eye 25.

A fuse cutout of the prior art will open the circuit on high currents due to melting of the fusible element. The fuseless cutout of my invention should operate in response to high currents and accordingly any suitable current responsive means may be provided for releasing latching means 21. This current responsive 'meanshas beenspecifically illustrated in Figs. 1 and 2 as of the electromagnetic type. Accordingly, in Fig. 1 there is disclosed electromagnetic means generally indicated at 30 comprising the magnetic structure 3|, the winding 32 and the armature 33 biased to the upward position by means of a spring 34. This electromagnetic .means :30 is supported on a suitable insulating .m'ember 35,-whichin turn is fastened to :the other end'of the u-shaped conducting support -2I as indicated at '35. One end of winding 32 is .electrically connected as by means ,of conductor 31 with U-shapedconductingsupport -2I, while :the other end of winding32 is connected to line terminal 38 which isconnectedto .a suitableexternal circuit as illustrated by conductor .39. The current responsive setting of electromagnetic .means 30 may be adjusted by varying :the adjustment of a screw '40 which in turnvaries the compression of spring 34 thereby :requiring a higher current to move;plunger, orarmature T33, :downwardly if the compression :of spring .34 is increased.

In order that electromagnetic means 30 may release latch 2.! upon the occurrence .of abnor- -mal current conditions flowing in the circuit I-939, armature 33 of electromagnetic means :30 is connected to a rod II which includes --at the upper end thereof anelongated slot 42. .An -extension 43 rigidly connected to latchingmember 21 extends through the slottedopening l2 in such "a manner that sufficien't-downward movement .of

.rod 4| will cause clockwise rotation vofextension .orarm'43 and consequently also of latch .21 ,to release resilient arm :22 and produce high-speed separation of contacts -I4and I5. Whenthe'current flowing through contacts ---I4 and .I5,resilient arm 22, U-shap'ed conducting support 2|, :con-

ductor 31 and winding 32, which'are all-in series, reaches a sufficiently high value asdetermined bythe electromagnetic means 30 and 'the'adjust- :ment-of screw 4!], armature 33 and consequently rod 4l are pulled downwardly sufiiciently-to itrip latching means 21 whereupon-resilient arm 22 .is no longer restrained and high'spee'd :separationof relatively movable contacts I4 and l;5-:results .Withthe consequent interruption of the circuit.

Although I have illustrated the resilient .arm 22 as .forminga part :of .the lower terminal contact assembly I3, it will besobvi-ous that itmight just as well form a part .of the upper terminal contact assembly. Also, althoughI have illustrated the tripping mechanism as :being :exposed totheweather, it is obviousthat a suitable'housjin umay be provided which could readily be sup- .ported on U-shaped conducting support 2|.

Manual opening of the circuit interrupter disclosedin Fig. 1 may be accomplished by pulling downwardly on resilient arm 22 with sufficient force to release latching means 21, or by pulling --downwardly on extension '43 An appropriate insulated maintenance tool would be used for this purpose. It would not be desirable, however, to open the circuit by pulling downwardly on a maintenance tool which engaged eye 25, since such action might interfere with the high speed opening of the circuit breaker after latch 21 has been released. The eye 25 is provided primarily for relatching the circuit interrupter in the closed position after it has operated. Such relatching is accomplished by merely moving resilient arm 22 upwardly until it is again latched in the position indicated in Figs. 1 and 2 with the contacts 14 and I5 in current carrying engagement.

It will be obvious that the electric circuit interrupter described above may replace the fuse cutouts of the prior art with the obvious advantage that a lineman can reclose the circuit upon operation thereof by merely pushing upwardly on resilient arm 22 without the necessity of replacing a part of the device, and without any reason for or opportunity to change the operating characteristics as by replacing an improperly rated fuse link in the fuse cutouts of the prior art. Furthermore, the downward po sition of resilient arm 22, which is visible from a considerable distance, will indicate that the circuit interrupter has operated and consequently no additional indicating means for this purpose is required.

It will be obvious that the current responsive mean for operating the circuit breaker might comprise a bimetallic element instead of the electromagnetic means described in connection with Fig. 1. Accordingly, in Figs. 3 and 4 there is illustrated a modification of my invention in which the current responsive means is bimetallic instead of electromagnetic The corresponding parts of Figs. 3 and 4 are designated by the same reference numerals as in Fig. 1. In this case the U-shaped member 2i of Fig. 1 may be replaced by an L-shaped member 44 with the lower end thereof terminating in a terminal 45 connected to an external circuit such as conductor 39. The resilient arm 22' is very similar to the resilient arm of Fig. 1. Supported from the end of conducting support 44 is a bimetallic latching means 46 which is quite similar in shape to the latching means 21 of Figs. 1 and 2. In order to insure that the current flows through the bimetallic means 46 the supported end of the resilient arm 22' is insulated from conducting support 44 as by insulating members 41 and 41. The current flowing through movable contact I 4 must therefore flow through the free end of resilient arm 22, then through bimetallic latching means 46 and conductin support 44 to terminal 45. A backing member 48 similar to the backing member 26 of Fig. 1 is provided. However, this backing member is provided with an insert 49 of insulating material which is normally in contact with resilient arm 22' so that when the circuit breaker is in the closed position no current can flow through the backing member 48 to conductin support 44 but all the current must flow through bimetallic latching means 46. However, between the time that bimetallic latching means 45 releases resilient arm 22' and the time that the arc is extinguished between relatively movable contacts l4 and I5, the backing member 48 must carry the current so that no arcing occurs between bimetallic means 46 and resilient arm 22'. Consequently the lower portion of backing member 48 is formed of conducting material electrically connected with conducting support 44. The length of backing member 48 is of course dependent upon the contact separation of contacts 14 and [5 at which are interruption is certain to have occurred.

With the circuitinterrupter of Figs. 3 and 4 in the closed position all of the current must flow through bimetallic latching means or member 46 by virtue of insulating members 41 and 41' and insulating insert 49. When the current reaches a predetermined amount bimetallic latching member 46 is deflected sufliciently to release resilient arm 22 which begins to move downwardly at high speed to separate contacts l4 and I5. Slight downward movement of resilient arm 22 will cause it to electrically engage the conducting portion of backing member 48 so that the only arcing which will occur is within the expulsion tube 20 and which will be extinguished at high speed.

The operation of the arrangement disclosed in Figs. 3 and 4 will be obvious in view of the detailed description included above.

Although in Fig. l a compression spring I6 is provided to furnish a contact wipe, it should be understood that such contact wipe might be provided by the inherent resilience of arms 22 or 22 or of the tube supporting arm II.

In the arrangement described thus far the fuseless cutout must be manually reclosed after a circuit operation which corresponds to replacing the fuse in the fuse cutouts of the prior art. However, my invention is also adapted to be embodied in a reclosing type of fuseless cutout and a reclosing circuit interrupter embodying my invention is illustrated in Figs. 5 and 6, the corresponding parts being indicated by the same reference numerals as in Fig. 1. The circuit interrupting device shown in Fig. 5 is essentially the same as in Fig. 1. The lower terminal contact assembly, generally indicated at 50, comprises a conducting support 5| very similar to the U-shaped support 2! of Fig. 1. Resilient conducting arm 22 is electrically connected to conducting support 5!, as indicated at 2!. The contacts l4 and I5 are held in the closed circuit position against the inherent action of resilient arm 22 which tends to move downwardly, by a latching means mounted on conducting support 5|. This latching means comprises a backing member 52 and the latching member 53 which is pivotally mounted as indicated at 54 and biased in a clockwise direction, as viewed in Fig. 6, toward backing member 52 by spring means 55. Rigidly mounted to latching member 53 is an extension member 56 which is adapted to be engaged in the slot 51 of rod 58 connected to armature 33 of electromagnetic means 35. The construction described thus far is substantially the same as that shown in Fig. 1. Electromagnetic means 39 is mounted on an insulating member 59 very similar to the insulating member 35 of Fig. 1. This insulating member 59 is supported from conducting support 5| as indicated at 60.

In order automatically to reclose the circuit through contacts [4 and [5 upon opening thereof, it is necessary to provide means for apply ing an upward force to resilient arm 22 to cause it to relatch in the closed position. To this end I have provided resilient arm 6| provided with a coiled portion 6| so as to tend to move arm 6| in an upward direction. Arm 6! might comprise a rigid arm with separate biasing means 7 but is gpreferably :made .of .heavy "wire, :heavier than that from which arm .-22;is :made,-.so that when :arm ,6! .is :free to move it .is capable of forcing arm 22 to .its closed circuit position. .Arm -6! may "be-supporteddirectly below arm 22 and as shown may be held in position by the 'same means which holds resilient -.arm 22 :in position. 'Supported'on the 'outer end of resilient arm .i-sa memberfiZ having forkedend fiZ for engag- "ing resilient-arm 2-2'-'during the circuit :re'closing operation. .In order to preventaresilient arm '6: from moving upwardly and continually holding resilient arm 22in the closed circuit ;position,.1 provide .a latch 63 comprising the pivotally mounted latching member 454 and the backing ,member .65. The latching member .64 is ;pro-

.vided'with-a pair of extensions 66 'and :61. The .extensiomfiti is adapted to be engaged by-spring .68 clearly shownin Fig. 6, which will hold the latching memberzod in either the open or closed position when moved toeitherof these positions. The latchtis adapted to'be operated by engagement of theextension Bl with a rod 69 pivotally mounted at one end, 'as .indicatediat llL'to conducting support 5| and pivotally mounted 'at the other end, as indicated at ill, to the free end of resilient arm 61.

A member 12 rigidly .fastened to rod 53 attached to the armature 33 of electromagnetic means .30 is adapted toqengagearm fill. Member 12 may be positioned as shown in solid lines so .as to cause downward movement of 'arm '69 immediately upon movement of rod 58 and armature '33 or may be positioned on rodr58eas indicated by-dotted lines '?2' so rod 58 can be pulled downmore quickly to trip latch -rnember 53 and free resilient arm'22 for opening con- .tacts UlandJS-and then member 5-2 canengage arm :69 so as to cause tripping of:latch 54. Upon the .occurrence of an abnormal current condition electromagnetic :means sll'will not:on1-y trip latching member 53 in the same imanner as occurred in Fig. 1 but in addition by virtue :of member 12 and armilg resilient armlfil-would be pulled downwardly, and stressed to an even greater extent than inthe position shown in-Fig..=5. Such .downwardmovement of arm --69--will cause it -to move latchingmember 6.4 to the-open position by virtue of vextension.G'Land thereafter latching member '62 will be maintained in theopen position until .again engaged by armed!) in its upward movement .to the positionindicated in Fig. 5. 'It can be seen-that .theposition-of member 52, whether .it .be the dotted line position indicated at 5.2 or .thefull line positionindicated at 32, will control the .initial tension of spring 34 armature "33 must overcome .inorder to pull rod 58 down and thus the time .to :eifect the tripping of. latchmember .53. This would permit instantaneous opening of contacts 1dand-liwith member F2 .in the dotted lineposition on vrod .53 and maximum time .delay with -member 1.2 vin the fullflineposition onrod 58. vA further control of the time delay is provided .by spring 43% and screw 48 in the same manner .as-.-shown. in Fig. 1.

It .willbe understood that means should ,be provided for delaying the reclosureof contacts i4 and following the extinguishing of the arc'therebetween. Accordingly,.in Fig. 5 Ihave generally indicated 'atime delay and totalizing mechanism which is operated by a lever 13 pivotally connected to arms "6! andE'Q as indicated at Ti. This time delay and totalizing mechanism, generally indicated at "14, may com- 'jrprise an escapement -mechanism for .any tether suitable timing .mechanism. I prefer :to use =a time-delay and totalizing mechanism-constructed in accordancewiththat disclosedin U.-S. Letters .Patent .-2,069=,082, granted January 26, 1937, :and assigned to thee-assignee :of the present applica- "tion. Sucha, time .delay and-totalizing mechanism, after a predetermined number 'of consecutive-operations would be arranged -=.to lock the .arm 69 in adownward position -and consequently .-lock the :circuit breaker in the open position, as :in the above mentioned U. :8. Letters Patent ..2:,069-,082. In certain cases, however, it might be desirable to lock the circuit breaker in the-closed 4positionas'disc1osed and claimedin my 'copend- .ing joint application, Serial No. 468,522, filed .December 10, 19.42, now Patent No. 241-45186, J an. 21,1947, and assigned to the same assignee .as the :present .application. -In accordance with the [teachings of this copending joint --app1ication, .=the arm 59 after a predetermined number of'consecutive operations-would cause the contacts A l and lfi to :be locked in the closed position. Itshould be understood that the time delayand totalizing mechanism M may be any .suitablmmechanism and forms no part of the .present invention :insofar as the specific :con-

struction thereof is ,concerned.

:In .view of the detailed description included above, the operation of the reclosing circuit interrupter illustrated in .Figs. .5 and 6 will back:- .vious. .Anabnormal current will cause armature .33 of electromagnetic :means 35 to move downwardly. This movement willnot-only-triplatch- .ing member 53 with the consequent interruption of the .circnitat contacts Hand 15 by the high speed downward movement of resilient arm 22 but will also .pull .resilient arm -.BI and arm -69 downwardly. Downward movement of arm .69 .will open .latching member 64. As soon as the .circuit is interrupted at contacts 14 and 15 armature .33 .is iree .to move upwardly and is moved in thatdirection under the-biasof spring .314. Howeventhe time .delay mechanism is prevents resilient .arm .81 and arm -69 from-moving upwardly at high speed, :sincea predetermined time'delayis introduced. When this predetermined time-has elapsed, arm .6! moves upwardly atlhigh speed .andsince latch :64 is open it does not impede or stop the upward movement of resilient arm I6"! whereupon resilient arm .22 is .moved .to..its latrjhedpositionand the circuit is .closed .at contacts 14 and 15. When arm .69 .moves upwardly past the :extensionfil of latching inemberiiill the latchingmember is moved to its latching .position so as .to.latch resilient ,arm "Si when it againlis moved to the position indicated in .Fig. 5. However, if excessive .current again .flows through the circuit interrupter, armature Z33 will .be pulled downwardly so as to again .trip openlatch .61! and the reclosing-and opening operations will function as hereinbe- .fore -..'c-.escrib.ed until the totalizing mechanism included inif'ilocks open or .locksclosed the-contacts Ji l and 15 .as described above. In performing .such subsequent opening operations immedialtelyfiollowing the initial .reclosing operaticn-whichwould occurin the-event of a per-- manent fault, armature-33 must pull arm 69 as well as.r.od Eilior agreater distancethan-onthe initial opening operation thereby introducing time ..delay..in such subsequent opening operations. .IInanyevent rod 258 andarm iiil :move downward .sufficientlyto permit resilient arm :22 quickly 'to.separatecontactsfi-l-d land [5 thenecessary amount before latch 53 is tripped as hereinbefore described. Electromagnetic means 30, member '12 and arms GI and 69 are so constructed that normal load current flowing through electromagnetic means 39 will be sufiicient to latch arm 69 so that the fuseless cutout will reset to the initial operating position, shown in Fig. 5, after clearing a temporary fault from the line. Whenever resilient arm 22 moves downwardly, it engages the forked end 62 of the member 62 and rests therein until the reclosing operation is performed. Preferably the time delay and totalizing mechanism 14 is such that after one, two or three successive reclosures and openings of the circuit breaker the arm 6| will be locked in either its open or closed position in accordance with the prior art referred to above.

While I have shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention 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.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A circuit interrupting device for use on high voltage distribution circuits comprising an insulating column-shaped support, a rigid arm fixedly mounted on and extending from one end of said support, an arc expulsion tube immovably fixed to the free end of said rigid arm, a resilient arm extending from said column-shaped support, one end of said resilient arm being immovably fixed to the other end of said support and extending outwardly therefrom, said arm being inherently resilient to cause relatively wide resilient movement of the free end thereof, a contact mounted on said rigid arm within said expulsion tube, another contact engageable with said firstmentioned contact mounted on said free end of said resilient arm so that the resiliency thereof constantly biases said contacts out of engagement, a support member of conducting material rigidly mounted on said other end of said columnshaped support and current responsive releasable latching means mounted on said support of conducting material and having an element electrically connected to said support, said latching means being engageable with said resilient arm to normally hold said contacts in engagement and responsive to a predetermined current through said contacts to release said resilient arm and permit separation of said contacts.

2. A circuit interrupting device for use on high voltage power distribution circuits comprising an insulating column-shaped support, a rigid arm fixedly mounted on and extending from one end of said support, a line terminal mounted on said rigid arm, an arc expulsion tube immovably fixed to the free end of said rigid arm, a resilient arm of conducting material extending from said colum-shaped support, one end of said resilient arm being immovably fixed to the other end of said support and extending outwardly therefrom, said arm being inherently resilient to cause relatively wide resilient movement of the free end thereof, a contact electrically connected to said line terminal mounted on said rigid arm within said expulsion tube, another contact engageable with said first-mentioned contact mounted on said free end of said resilient arm so that the resiliency thereof constantly biases said contacts out of engagement, a U-shaped support of conducting material electrically connected to said resilient arm mounted on said other end of said column-shaped support, a second line terminal mounted on and electrically insulated from said U-shaped support, a releasable latch pivotally mounted on the free end of one of the arms of said U-shaped support engageable with said resilient arm to normally hold said contacts in engagement, and electromagnetic means mounted on the free end of the other arm or" said U-shaped support and having a winding with the ends thereof connected respectively to said U-shaped conducting support and to said second line terminal, said electromagnetic means being responsive to a predetermined value or" current through said contacts to disengage said latch from said resilient arm and permit separation of said contacts.

3. A circuit interrupting device for use on high voltage distribution circuits comprising an insulating column-shaped support, a rigid arm fixedly mounted on and extending from one end of said support, a line terminal lted on said rigid arm, an arc expulsion tube ir ovably fixed to the free end of said rigid arm, a resilient arm of conducting material extending from said column-shaped support, one end of resilient arm being immovably fixed to the other end of said support and extending outwardly therefrom, said arm being inherently resilient to cause relatively wide resilient movement of the free end thereof, a contact electrically connected to said line terminal mounted on said rigid arm within said expulsion tube, another contact engageable with said first-mentioned contact mounted on said free end of said resilient arm so that the resiliency thereof constantly biases said contacts out of engagement, a support member of conducting material rigidly mounted on said other end of said column-shaped support, a second line terminal mounted on and electrically connected to said conducting support and bimetallic means mounted on and electrically connected to said conducting support engageable with said resilient arm for holding said contacts in engagement, said bimetallic means being responsive to a predetermined current fiowing through said contacts to effect disengagement from said resilient arm and permit separation of said contacts.

GEORGE F. LINCKS.

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

UNITED STATES PATENTS Number Name Date 254,099 Plush Feb. 21, 1882 493,380 Hammarstrom Mar. 14, 1893 1,393,344 Conrad Oct. 11, 1921 1,491,799 Haywood Apr. 29, 1924 2,057,093 Geisslinger Oct. 13, 1936 2,069,082 Walle Jan. 28, 1937 2,159,884 Crabbe May 23, 1939 2,315,618 Huiistutter Apr. 6, 1943 2,331,778 Hill Oct. 12, 1943 2,349,609 Brown et al May 23, 1944 2,381,294 Langstroth 1 7, 1945 2,401,656 Mosley June 4, 1946 2,424,126 Smith, Jr. July 15, 1947

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