US2357853A - Electric circuit breaker - Google Patents

Description

Sept. 12, 1944. s. R. SMITH, JR 2,357,853

ELECTRIC CIRCUIT BREAKER Filed Sept. 26, 1942 Invent or: Sidney R Smith Jr,

by 56 MWA., His Attorney Patented Sept. 12,' 1944 ELECTRIC CIRCUIT BREAKER Sidney R. Smith, Jr., Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Application September 26, 1942, Serial No. 459,'?91

19 Claim's.

a suitable holder and they are usually located in close proximity to the high tension conductors as a consequence of which they are relatively inaccessible for inspection and maintenance. Difiiculties have been encountered in providing fuse cutouts having an electric use convenient for installation and inspection and at the same time capable of being 'emovable and replaceable. In any event, an abnormal electrcal condition occurring on a circuit protected by a use cutout will destroy the use and hence require replacement thereof. Although recent experimentation and research have reduced the cost of the replaceable elements, nevertheless such cost is still appreciable and it would be desirable to provide a useless cutout which would automatically interrupt the circuit under abnormal electrical conditions and yet wherein it is unnecessary to replace any elements after the protective operation of such cutouts, as is necessary with the fuse cutouts of the prior art. h

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

It is another object of my invention to provide a new and improved fuseless cutout which is simple and compact, economical in construction, which gives an immediate and reliable indication of the actuation and condition thereof, and which may be used in connection with prior art housings for fuse cutouts.

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 theclaims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawing 'in which Fig. 1 is a side View, partly in section of my fuseless cutout in the normal operative position with the contacts in the current carrying position, Fig. 2 is a partial view similar to Fig'. 1 showing the device after the circut'has been interrupted, and Fig. 3 is an exploded view of a portion of the useless cutout of my invention.

Referring now to the drawing, I have illustrated my invention in connection with an insulating support or housing o of porcelain or similar insulating material, of the size and shape used in connection with the fuse cutouts of the prior art, such. as is disclosecl, for example, in United States Letters Patent 2,081,813, granted May 25, 1937, upon an application of B. R. Hermann and assigned to the same assignee as the present application. Housing iii is preferably provided with an integrally ormed electric creepage and gas barrer H, disposed between stationary contact assemblies generally indicated at az and !E supported in spaced relationship in housing lil. To the rear of the housing lil is Secured a mounting bar !4 for the attachment of the casing to an electric line pole and cross-arm structure or the like. A'hinge bracket is suitably secured to the ihner rear wall oi' .housing ic in the same manner as are the contact assem'blies iz and 63; preferably these members are cemented in the recesses in the rear Wall of the housing as shown in the drawing. Braclet t includes a pivot pin iii by means of which a circu't breaker to be described lereinaiter is pivotahy supported tnererom.

Contact assemblies ta and i3 include line terminals iz" and 83' respectively which are adapted to have line conductors or leads fastened thei-eto by means of suitable clamping screws or the like. The upper contact assembly iz comprises a contact finger i? backed up by means of a spring strip !8 which serves to press the finger ti downwardly. The upper contact assembly also includes a terminal clip !9 which is arranged to receive the terminal cap 20 l of my improved circuit 'breaken which is similar to the terminalcaps of the fuse holders of the prior art The lower contact assembly [3 also includes a Contacting surface 2! which is adapted to be engaged by e. pivotally mounted contact finger 22 similar to the pivoted contact members of prior art construction. In other words the housing I U described thus far is adapt- V ed te serve as the housing for the use cutouts of the prior art as well as the housing for my new and improved fuseless cutout so that prior art constructions employing fuse cutout devices .through which tubular casing 2S.is adapted to ai i pass. One end of tubular casing 25 isclosed by 'either case.

may be readily converted to useless cutout installationsstill-retaining the same housing in 'The openside at the front of housing w is closed by means oi a door or cover 23 preferably constructed of insulating material. This door 23 supports an electric circuit breaker generally'indicated at 2| -'tg5 be described in greater detail liere'inafter. 'On'the outer' face of' the 'door or cover 23, there is formed an eyelet han- 19 hreaker may be bodily removed from casing n whereupon the contact assembiles l2 and l3 are completely isolated frcmone anothen v Door mounted circuit breaker 24 preferably comprises a tohular casing 26 of insulating material such as fiber orthe like, which when sub-: 5

iected to the beat of an electric arc evolves anarc-extinguish'ng gas. Tubular casing is suitably supported in a castingz'l having aca'singu supporting opening 28 therein. Casting 21 is suitably bolted to door 23 as by means of bolts' or rivets passingthrough openings 29 bestshown in Fig. 3. The casting 21 cooperates with a'recess 30 in door 23 to form an enclosure within which certain parts of my electric 'circuit breaker generally indicated at 24, are located as willbe described in greater detail hereinafter. The upper end of tubular casing 26 is preferablysupported by an integral extension 3l of *door 23 which is provided with anopening 32 therein terminal cap 29 as was described above, which is thradedlymounted on 'the u'pper end thereof.

A lower terminal 33 for tubular casing 26 is fastened thei-'eto as by' any suitable means such' as 45 pin 34 and comprises an extension 35 for pivotally by spring means 36 in a direction to engage the' contact surface z of the lower contact assembly) |3.` In order to insure good electrical' connection 50 'between pivotally mounted contact flnger 22 and the lower contact terminal 33 of tubular casing 25, I i'nterconnect these members bymeansof a fiexible shunt 31.

Mounted within 'tubula" casing 26 a retract- 56, A

' 45 -protrudesthrough able assembly shown in Fig. '2-which comprises an upper terminal button 38, a lower terminal 39, tension spring 43, a metal tube 4land flexible shum n. e

adapted to seat on the up'pe'r end of tubular cass'o Upper terminal button 38 is ing 26 so as to be clampedin position by terminal cap 20 with which good electrical contact is made.

In order to sea the upper end of tubular-casing 25 a. suitable gasket as shown in Fig. 2 may be provided. The' lower terminal 39 of the retractable assembly forms' the .movable contact of elctric circuit breaker 24 and is adapted for -reciproca movement within the bore 44 of tubular e s zs from an extreme upper position 'against the lower end of metal tube ll as shown in Flg. 2

j 'to a position just`outside the. lower end of casing 26 ass hown in`Fig-.' 1. ;Upp'er terminal button 35 and movablcontact 39 are electrically inter- 'connected'by flexible Shunt 42:* Tension spring :40 tends to draw movable contact 33 ,into tubi'lar `75 casing 26 to the position indicate& in 2,- the jupward movement thereof *being stopped by a tubular liner such as'metal tube 4l whose purpose will be described hereinafter. Movable contact 39 which forms the lower terminal of the retractable assembly described above is provided with an annular groove and is adapted to be electrically engaged by means of an extension 45' on a hinged contact member 46 which although slightly movable about hinge or pivot 41 supported by casting 21 in recess 30 really formsthe stationary contact of my circuit breaker 24. In other words, movable contact 39 and cooperatingcontact 46 form the relatively movable contacts of circuit breaker 24 so that relative'separa-` -tion thereof *is adapted to draw an are thereadjustment of the catch of the latchin means V supporting contact flzger zz which is biased 'as ?in an- A outward a I provide an between within the bore 44' of tubularcasing 25.

The annular 'groove 45 in movable contact 39 together .with a projection 45' of hinged contact 45 which will'hereinater be referred to as stationary contact 45,'provides a latching means for holding the relatively movable Contacts 39 and 46 in current carrying engagement as shown in Fig. 1 against the action of the retractable assembly including tension spring 43 so long as some means is provided to hold hingecl 'contact member 45 in the position with the extension 46' protruding through opening 21' of casting 21 to ,engage the annular grcovjs .of 'movable concontact 45 which is adapted to engage with a catch supported at the free end of a bimetallic element 51. This bimetallic element ,5l is mounted in the recess 30 as by means of a bimetallic element terminal 52 which is adjustablymounted to a ledge 53 of door 23 in recess 30. The adjustable mounting comprises a slotted opening 54' in bimetallic elementi terminal 52 which permits 48 with relation to'tooth 49 supported by hinged contact 46. In order that no current may be carried by the latching'means '43 including tooth 49 and catch 50', tooth 49 is suitably insulated as indicated at 55 in Fig. 3 from hinged contact 46. A fiexible 'Shunt 56 interconnects hinged contact 43 with the free end of bimetallic element 5| to complete 'the electrical connection therebetween. The bimetallic element terminal 52 e on the' other hand is electrically intrconnected.- with-the lower terminal 33 of tubular casing 26' by means of flexible shunt 51.

.whenever the extension 46( of hinge contact opening 21' of casting 21 and is'held in the annular g'rcove45 of movable contact 39 by latching means ing engag'ement until release of the [latching means as by flexing of bimetallic element 5| occurs. Manual release of the latching'means 48 may be accomplished with the aid of a manualy operable plunger or-member samounted in the lower part of door,'or' cover 23, and'biased direction by spring means. 53. If plunger' 58 is moved in'wardly, it engages the catch 50 of the latchi'ng means 48 and releases it 'romtooth 49.' A

m order to aid in the extinguishment of the arc drawn withinthe bore 44 o! tubular casing 25 upon relative separation of cont'acts 35 and 45,

diameter substantiallyequal to the diameter of movable contact' 33 as best indicated in Fig; 2.

t'ct 39. In order toholdhinged contact mem-` ber 46 in the engaged position ;with movable contact 39, I provide latching means generally indicated at 48, which comprise a tooth 49 on hinged:

48, as shown in'- Fig. 1, the Contacts are held in current carryrod 50 having an outside position.

'tubular casing 26 whereupon an annular bore is dened between the outer surface of insulating rod 60 and the bore 44 of tubular casing 26. This annular bore provides an arc space for the arc drawn upon relative separation of contacts 39 and 46. Insulating rod 60 is preferably formed v of a gas-evolving insulating material so that the gas evolved therefrom aids in the rapid extin-. guishment of the arc drawn upon operation of circuit breaker 24. By virtue of the annular arc space, more rapid cooling of the arc is provided -which consequently speeds up the interrupting process and furthermore the arc is forced or confined into a relatively small space so as to engage with 'a large area of insulating -material from which gas is evolved when subjected to the heat of an electric arc.

To support door 23 and circuit breaker 24 from pivot pin l6 of bracket 15, a suitable hook-shaped member 62 is provided which is pivotally mounted to casting 21 as indicated at 63. Hook-shaped member 62 is adapted to engagewith the pin 16.

of bracket l whereupon the door mounted circuit breaker 24 is pivotaly mounted so that if terminal clip !9 is disengaged from terminal cap 26, door 23 would pivot about the pin !6 of bracket !5 to the open position' Hook 62 is provided with an extension 64 including a guide member 65 which engages with insulating rod 60 to guide it in its movement into tubular casing 26 during the circuit interrupting operation. -Hook 62 is also provided with another extension 66 which engages with a tooth 61 on hinged contact 46 so as to prevent pivotal movement of hook 62 relative to bracket 21 about pivot 63 when contacts 39 and 46 are in current carrying engagement. In other words the circuit must be broken between relatively movable contacts 39 and 46 before door 23 can drop open.

As soon as extension 66 is released from engagement with tooth 61 the circuit breaker assembly is permitted to move downwardly both by virtue of gravity and the force of spring backed contact finger 'l about pivot 63 so that terminal clip l9 is released from terminal cap by the downward movement of the entire door-mounted circuit breaker 24,- whereupon the door drops to the open position. If it is desired to prevent the door from moving to the open position on the occurrence of a circuit-interrupting operation, a suitable screw may be inserted in opening 68 of hook 62 to engage with casting 21 thereby preventing pivotal movement about pivot 63.

In the collapsed position of the retractable assembly as was mentioned above, movable contact 39 engages with the end of metal tube 41. The purpose of this is to prevent the high gas pressures formed within the bore 44, of tubular casing 26 upon a circuit interrupting operation, from acting on the upper surface of movable contact 39 to force the contact back to the closed circuit In order to aid in resetting the circuit breaker 24 hinged contact 46 is provided with a manual lever 69 which extends out of the enclosure fol-med between casting 21 and the door 23.

With the door mounted circuit breaker 24 in thepositionindicated in Fig. 2, reclosing ofthe circuit through the fuseless cutout is accomplished by first'removing the door 23 and circuit breaker 24 mounted thereon from housing ID. Next the insulating rod. 66 .which ;should preferably be formed at the lower end thereof so as to provide a suitable grip for resetting, is grasped and pulled downwardly at the same time that manual lever 69 of hnged contact 46 is moved upwardly so that extension 46' thereof may protrude through opening 21' of casting 21 to make contact with movable contact 39 by engagng the annular groove formed therein. The upward movement of manual lever 69 of hinged contact 46 will cause tooth 49 to engage with catch 50 of bimetallic thermal element 51. Flexing of bimetallic thermal element 5 I, either due to an abnormal current fiowing therethrough or manually by Operating plunger 58 will cause release of latching means 48 and consequent interruption of the circuit within the annular bore i'ormed between insulating rod 60 and the interior surface of tubular casing 26. The interrupting operation is always performed between relatively movable contacts 39 and 46 so that when the door '23 moves to the open position, taking with it door mounted circuit breaker 24, an isolating action between the contact assemblies including terminal assemblies l2 and 13 is provided. The position of insulating rod 66 with or without the opening of door 23 gives a clear visual indication of whether the fuseless cutout of my invention has operated and requires resetting. Also the open cover or door 23, when dropped out, gives indication of operation.

The operation of the fuseless cutout of my' in vention will be obvious from the detailed description included above and no further description will be made. As will be evident from the foregoing description the present invention provides pronounced advantages over 'fuse cutouts of the prior art in that it is unnecessary to replace any parts before the circuit may again be completed after circuit interruption, it being merely necessary for the lineman to reclose the circuit breaker in the manner described above. Also, an indication of the condition of the fuseless cutout is at all times evident to the lineman.

Furthermore, a suitable arc interrupting means r for efiiciently interrupting the relatively high voltages found on distribution circuits is incorporated in the device.

While I have shown and described a particular embodiment of my invention for a fuseless cutout, I do not desire my invention to be limited to .Letters Patent of the United States is:

1. In an electric switching device, the combination of a housing and a cover for closing an open side of said housing, a circuit interrupter mounted on said cover comprising a pair of relatively movable contacts, a recess in said cover, and bimetallic means mounted in said recess for initiating relative separation of said contacts to in terrupt the circuit associated with said device, said circuit interrupter being so constructed and arranged that said contacts may be reclosed to reestablish an electric circuit therethrough.

2. In an electric switching device, the combination of a housing and a cover for closing an open side of said housing, a circuit interrupter mounted on said cover comprising a pair of rela i side ofsaid housing, a circuit interrupter mountsaid bimetallic means being arranged upon predeternined current conditions to permit said first mentioned means to cause relative separa- 'tion of said contacts to interrupt the circuit associated with said device, said circuit interrupter being so constructed and arranged that said contacts may be reclosed to reestablish an electric circuit thereth'ough.

3. In an electric switching device, the cambi nation of a housing and a cover for closing an -open side of said housing, a circuit'interrupter mounted on said covercomprising a tubular cassing, a painof relatively movable contacts, one of which is mounted in said casing, a recess in' said cover, and bimetallic means inountedin said recess for initiating relative separation of said contacts to interrupt the circuit associated with said device, said circuit interrupter being so constructed and arranged that said contacts may be reclosed to reestablish an electric circuit therethrough. r

4. In an electric switching device, the combination of a housing and a door for closing an open side of said housing, a circuit interrupter mounted on said door comprising a tubular casing, a pair of relatively movable contacts, one of whichis mounted in said casing, means for defim'ng an annular arc space in said casing so" that the arc drawn upon relative separation of said contacts is confined in said annular arc space for rapid extnguishment thereof, a recess in said door, and bimetallic means mounted in said contacts to interrupt the circuit associated with said device, said circuit interrupter being so,constructed and arranged' that 'said contacts may be reclosed to reestablish an electric circuit ftherethrougn 5. In an electric switching device: the combi- "hation of a housing and a door for closing an 'when said movable contact is moved out of said casing, a retractable contact assembly in 'said casing for causing withdrawal'of said movable contact into said casing'and relative separation `of said contacts, a rod of arc extinguishing material connected to said movable contact so as to 'be drawn'into said casing to deflne an annular arcspace thei-ein upon relative separation of said contacts, latching means for holding said con- `tacts in current carrying engagement against ;the force of said retractable assembly, a recess in said door, and bimetallic means mounted in said recess for initiating relative separation of said contacts to interrupt the circuit associated movable contacts, a recessin said cover and means mounted' in said recess for initiating relative separation of said contacts to interrupt the circuit associated with said device, said circuit inj terrupter being so constructed and arrangedthat said ,contacts may be reclosed to reestablish an electric circuit therethrough.

4 7. In an electric switching device, the combination of aihousing and a cover for closing an open side of said housing, a circuit interrupter mounted on said cover comprising a pair of relatively movable contacts, a recess 'in said cover,

.means for causing relative separation of said ing said first mentioned means inefiective, said additional means being arranged upon predefor initiating relative separation of said contacts,

.said recess for initiating relative separation of termined current conditions to permit said first mentioned means to cause relative separation oi said contacts to interrupt the' circuit associated with said device, said circuit interrupter being so constructed and arranged that said contacts may be'reclosed to reestablish an electric circuit therethrough.

-8. In an electric switching device, the combination of a housing and a cover* for closing an open side of said housing, a circuit interrupter mounted on said cover comprising a tubular casing, a pair of relatively movable contacts, one of which is mounted in said casing, a recess in said cover, and `means mounted in said recess to interrupt the circuit associated with said device, said circuit interrupter being so construc'ted and arranged that said contacts may be reclosed .to reestablish an electric circuit therethrough.

9. In an electric switching device, the combina- .tion of a housing and a door .for closing an open side of said housing, a circuit' interrupter mounted on 'said door comprising a tubular casing, a

pair of relatively movablecontacts, on of which is mounted in said casing, means for defining an annular arc space in said casing so that` the arc' drawn upon relative separation of said contacts is confined in said annular arc space for rapid extinguishmentthereof, a recess in said door, and' means mounted in said recess for initiating relative separation of said contacts to interrupt the circuit associated with said device, said circuit interrupter being so constructed and arranged' that said contacts may be reclosed to reestablish* an electric circuit therethrough.

10. 'In an electric switching device, the combination of a housing anda. cover for closing an open side of' said housing, a circuit interrupter mounted on said cover comprising a tubular casing, a pair of relatively movable contacts comprising a. movable contact-mounted in said casing and a cooperating contact member located outside said casing and adapted tobe in current carrying engagement with said movable contact when said movable'contact is moved out of said casing, a retractable contact assembly in said casing for causing withdrawal'of said movable.

contact into said casing and relative separation of said contacts, a rod of' arc-extinguishing mate- ,with said device by causing release of said latch-' i ing means, said circuit interrupter being so constructed and'arrangd that said contacts may be reclosedtdreestablish an electric circuit thereed, on said cover comprising a pair of relatively rial connected to said movable contact so as to be drawn' into said casing to denne an annular arc space therein upon relative separation of said 1. tacts in current carrying engagement against the force of said-'retractable assembly, a recess in said j contacts,- latching means for holding said concover, and means mounted in said recess for initiating relative separation of said contacts to interrupt the circuit associated with said device by causing release of said latching means, said circuit interrupter being so constructed and arranged that said contacts may be reclosed to reestablish an electric circuit therethrough.

11. In an electric switching device, the combination of a housing and a recessed cover for closing an open side of said housing, a circuit interrupter mounted on said recessed cover comprising a pair of relatively movable contacts, means for causing relative separation of said contacts, and latching means including bimetallic means mounted in said recessed cover for rendering said first mentioned means ineffective, said bimetallic means being arranged upon predetermined current conditions to permit said first mentioned means to cause relative separation of said contacts to interrupt the circuit associated with said device, said circuit interrupter being so constructed and arranged that said contacts may be reclosed to reestablish an electric circuit therethrough.

12. In an electric switching means, the combinaticn of a housing and a recessed cover for closing an open side of said housing, a circuit interrupter mounted on said recessed cover comprising a pair of relatively movable contacts, and means mounted in said recessed cover for im'tiating relative separation of said contacts to interrupt the circuit associated with said device, said circuit interrupter being so constructed andarranged that said 'contacts may be reclosed to reestablish an electric circuit therethrough.

13. In an electric switching device, the combination of an insulating support, a circuit interrupter hingdly mounted on said support comprising a tubular casing, a pair of relatively movable contacts one of which is mounted in said casing, means for defining an annular arc space in said casing so that the arc drawn upon relative separation of said contacts is confined in said annular are space for rapid extinguishment thereof, an enclosure associated with said support, and means mounted in said enclosure for initiating relative separation of said contacts to interrupt' the circuit-associated with said device, said circuit interrupter 'being so constructed and arranged that said contacts may be reclosed to reestablish an electric circuit therethrough.

14. In an electric switching device, the combination of an insulating support, a circuit interrupter hingedly mounted on said support comprising a tubular casing. a pair of rclatively movable contacts comprising a V movable contact mounted in said casing and a cooperating contact member located outside said casing and adapted to be in current carrying engagement' with said movable contact when said movable contact is moved out of said casing, a retractable contact assembly in said casing for causing withdrawal of said movable contact into said casing and relative separation of said contacts, a rod of arc extinguishing material connected to said movable contact so as to be drawn into said casing to define an annular arc space therein upon relative separation of said contacts, latching means for holding said contacts in current carrying engagement against the force of said retractable assembiy, an enclosure associated with said support, and means mounted in said enclosure for initiating 'rela'ti -e separation of said contacts to interrupt the circuit associated with said device -by causing 'release of said latchng means, said circuit interrupter being so constructed and arranged that said contacts may be reclosed to reestablish an ele'ctric circuit therethrough.

15. In an electric switching device, the combination of a housing and ,a door for closing an open` side of said housing, a circuit interrupter mounted on said door comprising a tubular casing, a pair of relatively movable contacts comprising a movable contact mounted in said casing and a cooperating contact member located outside said casing and adapted to be in current car rying engagement with said movable contact when said movable contact is moved out of said casing, a retractable contact assembly in said casing for causing withdrawal of said movable contact into said casing and relative separation of said contacts, a rod of arc extinguishing material connected to said movable contact so as to be drawn into said casing to define an annular arc space therein upon relative separation of said contacts, latching means for holding said contacts in current carrying engagement against the force of said retractable assembly, and bimetallic means mounted in said housing for initiating relative separation of said contacts to interrupt the circuit associated with said device by causing release of said latching means, said circuit interrupter being so constructed andarranged that said contacts may be reclosed to reestablish an electric circuit therethrough.

16. In an electric switching device, the combi- .natic-n of a housing and a door for closing an open side of said housing, a circu't interrupter mounted on said door oomprising a tubular casing, a pair of relatively movable contacts one of which is mounted in said casing, means for defining an annular arc space in said casing so that the arc drawn upon relative separation of said contacts is confined in said annular arc space for rapid extinguishment` thereof, and bimetallic means .mounted in said housing for initiating relative separaticn of saidcontacts to interrupt the circuit associated with said device, said circuitinterrupter being so constructed and arranged that said contacts may be reclosed to reestablish an electric circuit therethrough.

17. In a electric switching device, the combination of an insulating support, a circuit interrupter hingedly mounted on said support comprising a tubular casing, a pair of relatively movable contacts associated with said casing, one of which is adapted for reciprocal movement in said casing, a tubular liner for a portion of said casing, means for causing relative separation of said contacts to draw an arc in said casing and to cause one of said contacts to ;nove into said casing to' engage an end of said tubular liner whereby high gas' pressures produced in said tubular casing upon the drawing of an arc in said casing cannot force said one contact toward the closed circuit position.

18. In an electric switching device the combination of a housing and a recessed cover for closing an open side of said housing, a circuit interrupter mounted on said recessed cover comprising a pair of relatively movable contacts, means mounted in said recessed cover for initiating relative separation of said contacts to interrupt the oircuit associated with said device, and means engageable exteriorly of said housing but extending into said recessed cover for causing release of said means mounted in said recessed cover 'when manually operated, said circuit interrupter being so constructed and arranged that said contacts may be reclosed to reestablish an electric circuit therethrough.

19. In an electric switching device the combination of a housing and a recessed cover for 6 w nam-853 closing an open side'of said housing, a oircuit inter upter mounted on said recssed cover cemprsing a 'pair of relatively movable contests', bimetallic means mounted in said recessed cover for initiating relative separation of said contacts to intel-nipi; 'the circuit associated with Saidi-device, and a spring bised member engageable extor y of sai d honsing' b'ut extendin into said recessed cover -for release of said bimetanic means i when manuany operabed, said circut inten'upter being so constructed and arranged that said conv tacts may be reclesed to reestablish an electric circuit therethrough.

. SIDNEY R. sxqn'n, JR.

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