US2785345A - Circuit interrupters - Google Patents

Description

March 12, 1957 v. cHiABALA 2,785,345

CIRCUIT INTERRUPTERS Filed Nov. 27, 1953 2 Sheets-Sheet l Fig.|.

WITNESSESI INVENTOR /.Wy Leonard v Chobolo.

@WAN/Umain March 12, 1957 l.. v. CHABALA 2,785,345

CIRCUIT INTERRUPTERS Filed NOV. 27, 1953 Fig.3.

Rated Trip Current o Trip Current 2 Sheets-Sheet 2 VFig..4.

Normal Operating Temp.

Temperature 0 Temp. Drop from Operating Level.

Time

@7:35345 -cnzcnlr INTERRUPTERS Leonard yV. Chabala, Pittsburgh,-Pa., assigner to Westinghouse Electric CorporatiomfE'ast Pittsburgh, Pa.,.a

corporation of Pennsylvania .My invention relates generally to circuit interrupters, 4and it has .reference r in 'particularto Vautomatic reclosing circuit breakers. r

Generally stated, it isran object of my invention to provide for increasing the current rating of a reclosing circuit breaker when it has been open for a predetermined tirne, to permit it to handle increased currents upon reclosing, such as may be due-to loss of diversity of demand on the system.

lMore specifically, it is an object of my inventionto provide for changing the effective ampere turns of the operating coil of arecloser when the recloser is reclosed after-it has been A'open'for a predeterminedtirne.

/`Another object of my invention is to provide for decreasing the effective `ampere 'turns of the operating coil of a recloser when it opens, and formaintaining such decreasedcondition when the recloser recloses, only if 'the recloser remains open for a predetermined time.

Yet another objectof my invention is to provide for shunting a portion of the .ampere turns of the operating coil of Va re'closer whenit opens, and using a thermal latch for maintaining said shunted conditionif the temperature of the recloser falls below al predetermined level.

It is an important object of my invention to provide vfor shunting'the series operatingrcoil'of a reclosing circuit breaker when it locks lopen,vand f'orutilizing a latch having a bimetallicmember responsive to the temperature of the oil to maintaihrrsuch shunt in the eventthat the breaker remains open for a Asuliicientftime foruthe `temperature thereoffuto drop to a predetermined value.

Other objects will in .part be obvious, and will-in part be explained hereinafter.

-In' practicing my. invention in accordance with oney of itsembodime'nts, an auxiliaryswitch is disposed to -be .actuated vfrom the lockoutstoggle linkage of a reclosing vcircuit .breaker to `connect aJresistor in shunt withthe solenoid coil of the .breaker to increase its effective trip rating. `So as Ito'enable .the breaker to attain this increased rating when .reclosed-after arelatively long delay oftwenty minutes orso, .a bimetallic latch is provided that becomes effective only .when the breaker is open -for a .relatively long interval,.otherwise the switch opens and-removes the shunt vvwhen the recloser is reclosed.

vFor a more complete understanding of the nature and scope of my invention, reference may be made tothe yfollowing description which may be read in connection with the :drawings inwh'ich:

:Fig l.is..arsubstantially central vertical sectionfview of `a circuit breakeremb'odyingthe invention .in one of its forms; v:Fig l2 is an ,enlarged vertical sectional view in part of the vbreakcrshown in 'Fig. 1 taken to the .rear of the counter and atan angle to Athe section of Fig. 1;y

Fig. :3 is a .characteristic temperature-current Acurve .for the breaker shownyin-Fig. 1; and

`Fig. 4 is a characteristic -time-temperature .curve :for

, the same; breaker.

United States Patent ICC issubstantially the same as that described ,in Patent No.

2,622,167 of H. L. Rawlins etal. except that the dash- .erably a liquid having arc extinguishing ability suchras oil, Therupper end of tank 2 is provided with an out- `vvardlyextending flange 4 on which the flange 8 of a cover casting -6 is adapted to be seated, preferably, Awith a gasket 1 9 interposed therebetween. Cover casting 6 may be secured to the tank in any desired manner, such for example, as by bolts (not shown) secured torsuitably formed brackets on the tank.

The breaker contacts and certain of the contactactuating mechanismare adapted to be supportedin tank 2 from cover casting 6 by means of a pair of inte/gral supporting lugs 16 (only one of which is shown) depending from the top wall of the cover casting and adapted to engage insulating spacer rods 18 having threaded studs (not shown) engaging threaded openings in the rods, lugs 16 and a supporting casting 2i). A supporting plate 22. may be supported in a similar manner from casting 2li, so that a solenoid coil 24 may be mountedtbetweren casting 2) -and supporting plate 22, whichact 'as pole pieces with thevcentral opening in the coil aligned with openings provided in casting 20 and plate 22.

:Spaced stationary contacts 26 ofthe breaker are each ysupported from plate 22 by a support tube 28 of insulating material, such ,astiben with the stationary con- Ytacts being mounted on support 2S, by means of screws 3Q Aand with the upper end vof thesupport 28 having brackets 32Ybly means of which the support is securedto supporting plate 22.

vlimited pivotal movement about atransverse axis on con- `tact actuating rod 44. Contact rold744 should be of an insulating material such as ber or a molded insulating material.

The upper end ofgcontact actuating rod 44 has apair of connecting links 46 positioned one at each side thereof `and pivoted thereon as by a pivot pin 48, with the upper ends of these connecting links mounted on y,a `V` common pivot pin Stifor a pair of toggle levers 5,2 and 54. Toggle leverswSNZ and 54 are both formed of sheetmaterial, with lever 54being bent tosubstantially'channel form with outwardly extending flanges 56 adapted to be received at the free ends thereof in recesses S8 provided inuthe Vspaced downwardly depending fingers of yan angled supporting bracket 60 which, `in turn, is secured to a lug 62 integral with the coverfcasting. Preferably, v the base of the channel part of toggle lever 54 isgextended at 66 through the space between the supporting lingers of vbracket 69, 4and the other end oflever 54 the sides .of the channel formation thereof areextendedto be mounted on pivot pin 50. Lever 52 has avhooked extension 69 extending through lever :5,4 to limitseparation therefrom. A coil tension spring 68 has oneeud hookedrinto an opening provided in toggle lever 5.2, and has the opposite end thereofhooked over a spring support on the cover casting. Y i

Solenoid coil 24 previously mentioned is adapted to be opening the circuit .breaker-contacts. The central open- 3 ing through coil 24 preferably is provided with a cylindrical sleeve 74 in which a solenoid core 76 is adapted to be slidablyV mounted in a piston-like manner. The sleeve 74 communicates with an annular passage 73 in the casting, which connects with a passage Sti having a threaded end opening 81 for receiving a plug (not shown) if all time delay operation of the breaker is desired.

. A contact actuating sleeve S2 is telescoped over contact actuating rod 44 and its lower end is received in core 76 and preferably threadably mounted therein. A coil compression spring 83 is provided within actuating sleeve 82 on contact actuating rod 44 and is adapted to react between a shoulder in the core and a pin 84 extending transversely through actuating rod 44. A bushing 85 surmounts the sleeve 82 and is provided with a ange Se'.

The circuit through the circuit breaker thus far described may now be traced from the point where it enters tank 2 through one of a pair of terminal bushings 96 (only one being shown), each being provided with a conductor element which extends through the bushing seated in an opening provided in the top wall of cover casting 6, andv proceeds by conductor 98 directly to one fixed contact 26 of the breaker. When the contacts are in engagement, the circuit then proceeds through bridging contact 36 to the other fixed contact 38, and then by way of a conductor 166 to one terminal of solenoid coil 24.

' The other terminal of coil 24 is adapted to be connected by a conductor 102 to the conducting means in the other terminal bushing 90. It will be apparent that solenoid coil 24 in this embodiment of the invention is connected in series in the circuit through the circuit breaker so as to be energized at all times when the circuit breaker is closed, an amount dependent upon the value of current owing in the circuit.

For any given rating of circuit breaker, solenoid coil Y 24 is designed to become sufficiently energized when the load current in the circuit exceeds its rating sufficiently to attract core 76 and move it upwardly within sleeve 74. Core 76 will move upwardly relatively rapidly if the passage 80 is open, and slowly if it is closed, since it is necessary to displace the liduid in sleeve 74 above the core either through the opening 8l or through relatively small clearance between the core and sleeve '74. Accordincly if the opening 81 is open, as shown, opening f movement of the core will not be slowed up appreciably V`by the aforesaid dashnot action, and opening movement thereof maybe relatively ranid. When core 76 commences its upward travel. bridging contact 36 being engaged by toggle spring 63 does not move, so that spring .83 is compressed until it is substantially solid, at which point the upper end of bushing 85 strikes a collar 87 n secured torcd 44. Thereupon, actuating rod 44 moves l overcome the closing bias of toggle spring 63, preferably at some point during initial movement of core '76 before bushing SS engages collar 87 on actuating rod 44. However, collar 87 is provided to obtain a positive contact separation in the event there is any sticking or welding of the bridging contact to stationary contacts 26. In either case, it is apparent that toggle levers 52 and 54 will be moved to their on-center position in the manner previously described, and bridging contact 36 will be moved by spring 83. When the breaker contacts have attained their full open circuit position, the parts associated therewith are'biased to return by gravity.

In order to -limit the number of operations of the circuit breaker in close succession upon the occurrence of a continuing overload on the circuit, and to provide for manual operation, meansare provided for holding the reaker contacts open in response to the occurrence of a predetermined number of closely succeeding circuit interrupting operations, which means can be manually actuated. This means comprises a toggle lever 104 pivoted at one end as at 196 on a U-shaped spring lever 108 which, in turn is pivotally Supported as at 11% between the legs of a U-shaped supporting bracket 111 secured to cover casting 5. The other end of toggle lever 164 is pivoted, as by a pivot pin 112, to the adjacent end of a second toggle lever 114, and this, in turn, is mounted on a pivot pin 116 intermediate its ends, with the pin 116 being mounted in a bracket 118 secured to the adjacent wall of cover casting 6. A slot 120 is provided through the cover casting 6 for receiving the other end of toggle lever 114, which acts as a manual operating handle at the exterior of the circuit breaker casing, being provided with an angled hook end 122. A coil compression spring 124 is mounted to react between the bight of lever 168 and cover casting 6. Normally, toggle levers M34 and 114 are held by spring 124 with pivot 112 below the center line connecting pins 106 and 116, with the outer end of lever 114 positioned in and beneath an integral hood 126 on cover casting 6, in engagement with an adjustable stop screw 128 mounted in the hood.

In the position of toggle levers 104 and 114 illustrated, they have no eect on operation of the circuit breaker as previously described, being normally inactive in this respect. However, lever Hi8 has a connecting pin 113 extending beneath toggle levers S2 and 54. Accordingly, if it is desired to manually open the circuit breaker contacts, a hook stick or similar operating member may be engaged with the upper side of angle hook 122 of toggle lever 114 and pulled downwardly to rotate the toggle lever in a counter-clockwise direction about its supporting pivot 116 to move toggle levers 104 and 114 overcenter in an upward direction, and in doing this, pin 113 engages toggle levers S2 and 54 and moves them upwardly in a counterclockwise direction, thus carrying contact actuating rod 44 upwardly to separate bridging contacts 3S from stationary contacts 26. The contacts will be held open by spring 124, which maintains toggle levers 104 and 114 in their upper over-center position.

In thus manually opening the circuit, after toggle spring 68 is moved to its on-center position, it will be observed ythat the spring 124 is only required to maintain the contacts of the breaker open against the relatively light closing bias duc to gravity, and such light bias as may be due to toggle spring 68 in the event that toggle levers 52 and 54 are stopped just prior to reaching their on-center position. With the breaker contacts maintained at their open circuit position following the manual circuit opening operation described above, it will be apparent'that the outer end of toggle lever 114 projects below hood 126 of cover casting 6 so as to provide a readily visible indication that the breaker contacts are maintained at open circuit position. It will further be apparent that the breaker contacts may then be closed only by manual operation of toggle lever 114 in the opposite direction, that is, by exerting an upward force on the outer end ot the toggle lever by engagement of a hook stick or the like with the underside of hook 122,V to rotate lever 114 in a clockwise direction to move it and toggle lever 1434 back over-center to the full line position illustrated on the drawings. An integrating mechanism is provided for automatically moving toggle levers 104 and 114 upwardly over-center and thus preventing reclosure of the circuit breaker in response to a predetermined number of closely successive circuit interrupting operations, comprising a cylinl drical tube 130 clamped or otherwise secured in a lateral extension of casting 20 at the top of solenoid coil 24, and

l this tube has a plug 132 threaded into the lower end generally by the numeral 16d. As best shown in Fig.. 2

trolled by a ball check valve 134, which permits ow of :iluidiiiito thelowerendof-t11be.130.but prevents outow. .Anfintegrating .piston-13 6.is.mounted in tube 130 .and ,normally restsonthe upper endof plug 132, being provided with a reduced extension 138 atthe upper end .thereofhaving a .plurality of spacedcircular flanges 140 forming rack teeth thereonVandfhaving an elongated ex- A.tension 142 of insulating material .on the extreme .outer endthereofwhich is positionedbelow an extension 143 ontoggle leverlld. A pawl lever144ispivotally mount- .ed at one end asat 146, this end of .pawl lever being .split with legs located at each side of tube 13@ and with .pivot 146 .supported on spaced supporting flanges 145 integral with casting 2l). Pawl lever 144 has a conncctingweb intermediate its ends, and at the other end .t'hereofthesides .of theflever are extended outwardly and .laterally as at 148, to normally be in engagement with -ltlange.86.of.actuatingtube- 82 adjacentthe outer end of thistube. Pawl lever 144 is normally biased into engagement with flange. 6 by a coil tension spring 152 hooked over the remote edge of the web ofthe pawl lever at one end and anchored to an ear integral with casting 2i) at l.its other end. Pawl lever 144 is provided with a pawl member pivoted thereon as at 156, and biased by a spring A158'in a counterclockwise direction to a position 'Awhereina portion of pawl member 154 engages the connecting web of pawl-lever 144.

The tube 130 intersects the passage Sil of the dashpot,

and the piston y13rd acts as a valve to control venting thereof, so that with the piston as shown the dashpot .vents freely and. operation of the breaker is rapid. When the piston 136 isrmoved upwardly by the pawl 154, it lirst partially and then completely blocks the passage Si) so as to -delay operation of the armature '76 slightly, and then withl an inverse time current characteristic.

In order to permit 'the breaker to be reclosed and handle the additional load which accumulates due to loss of diversity of load after an extended outage, such as will occur when the breaker is reclosed after having locked open for a relativeiy long time of, say, twenty minutes or lmore, recalibrating means may be provided, designated 'a resistor 161 may be mounted adjacent coil 24, being, 'for example, secured to the lower plate 22 by a bolt 162 andinsulating spacer 163. An arm 165 may be pivotally nmounted,on plate 212 as by a pivot 166, having a contact for engaging a lixed contact 168 mounted on the upp'erfendof resistor 161 and spaced therefrom by insulation 159.v AV spring 17d biases arm away from casting 20.

The lower end of resistor y161 may be connected to the lower terminal of coil '24 by connector 171, while the upper Aend isconnected by a llexible connector 172 to y,Contact 167. Connector 173 connects fixed contact 168 .to the upper terminal of'coil 24, so that resistor 161 is connected in shunt with coil 24 when the switch arm is actuated to the closed position.

To actuate 165, a bellcrank 175 is pivotally mountedon projection 176 of casting 2), and connected to .toggle lever 114 link 177 and clevis 177 (Fig. l), so as ,toi be operated to close switch arm 165 each time the toggle relation of levers114, 104 is broken. A latch 178l having a bimetallic actuating portion 179 is mounted on casting 2l) so as .to be actuated downwardly to a position to retain arm 165' in the closed position, if the 'interruptor has been open for a1-predetermined time of say, abouttwenjty minutes or more, andH has cooled down sufficiently below thevnormal operating temperature, Ternerature'compensation may be elected by connecting a y ersely disposed bimetal element 186 (Fig. 1) positilo'ncd on `support rod 13 above the oil L to latch 173, as VVby imkl 182, that changes in ambient temperature will not the operation of the latch.

" f lien' the circuit breakerop'e'rates to open Vthe circuit, :jflaglge` 86` wi ll be carried upwardly with actuating sleeve 82 and thus carry the free end of pawl lever 144 upwardly V.with it to .move pawl member-,154 iuQ-.CngagementMith vbreaker remains closed, integrator pistonfldwillslowly reset to the position shown in Fig. l dueto leakageof lio id in cylinder Silbelow piston-136 through the relatively small clearance between the cylinder and piston.

vHowever, if the breaker immediately reopens after. .afirst opening and reclosing operation, pawl memberf154this time will engage the next lower circular ilangei on. the integrator piston and raise the piston afurther1 amount. Subsequent reclosing will resultA then .in leavingpiston 136 at this further advanced position from which .it eventually `will reset if the breaker remains closed. However, in the event of a continuing overload, f-the breaker will again open and reclose, and the pawl.member 154 advances integrator piston 136an amount sufficient to cause theupper extension 142 thereof to engage .the extension 143 .of toggle lever 164 and move vthis lever upwardly overcenter, so that toggle spring 124 will maintain the contacts separated in the manner previously described. It is thus apparent that toggle levers 104 and 11,4 will be automatically moved upwardly over-center to maintain the breaker contacts separated, only in responseto a predetermined number of closely successive circuitopening and closing operations, usually four such operations. However, in the event a lesser number of closely successive opening and closing operations occurs, the integrating mechanism will reset and the breaker contactswill be automatically held open only when the aforesaid predetermined number of opening and closing operationsoccurs in close succession. AObviously, after the breakercontacts have been automatically actuated toa position where they are held open by toggle spring124, theyv can be reclosed only by manual operation of toggle lever 114 in the. manner previously described.

When toggle levers 1 tl4rand3114are movedover-center, .link.177 vactuates bellcrank lever 175 counterclockwiseto Vclose switch arm 165. Resistor 161 is thereby placed in shunt with coil 24 so as to requirea greater value of .current to effect a subsequent trip operation.

Should the recloser be reclosedshortlyafter such locking open,V and before the usual diversity of load is lost, the operating temperature of the recloser, which will run on the order of 25 to 30 degrees centigrade abovearnbient, will not have dropped ksufficiently for latch178 to become effective, and spring 170will open switch arm 165 as bellcrank 17S is rotated clockwise by handle122. The interruptor will therefore have its. normal trip rating.

Should the recloserremain open forabout twenty minutes or more, so that the usual diversity of load is. lost, the temperature of the recloser willdrop as shown by ,curve (a) of 4, and latch 178 will be actuated downwardly by bimeta 1W so as to be effective to latch. arm

closed. Thus when the recloser is reclosed,.switch arm 165 will remain closed, and coil 24 will` be shunted by resistor 161, thus reducing `the effective Yampere turns thereof. Accordingly, the trip current rating of -Athe recloser will be increased, as'shown by curve (b) of Fig.

3, and the recloser will beA able tohandle theincreased load current due .to loss of diversity. v

From .the l'above description and the accompanying drawings it will beapparentthlat 1 have provided a reclosing circuit breaker with increasedcold load pickup, Vwhich .means thatthe. normal trip current may be much closer to the normal rating, .while stillpernii'tting `greater yovercurrents to behandled ifthe breaker has been .open for .some time soas to permitloadtoaccumulate. v.ing fthe arm 165 of vav magneticmat e rial,. ,the ,magnetic attraction between arm 165 and casting 20 may be utilized to prevent interrupting excessively heavy currents at the switch arm contacts, such as might occur should latch $.76

be released during an overload. Existing breakers may be readily modified according to my invention with a minimum of labor and expense.

Having described a preferred embodiment of the invention in accordance with the patent statutes, it is desired that this invention be not limited to this particular construction inasmuch as it will be apparent, particularly to persons skilled in this art, that many modifications changes may be made in this particular structure without departing from the broad spirit and scope of this invention. Accordingly, it is desired that the invention be interpreted as broadly as possible and that it be limited only as required by the prior art.

I claim as my invention:

1. A circuit interrupter comprising, separable contacts, an operating mechanism therefore, electrorcsponsive means operable to actuate said mechanism to eiect separation of said contacts, lockout means actuated by a predetermined number of operations of the electroresponsive means to maintain said contacts separated, switch means actuated by the lockout means operable to vary the etico tiveness of said electroresponsive means when the contacts are maintained separated, and releasable means operable in accordance with a predetermined temperature condition of the interruptor to maintain said switch means operated.

2. In a circuit interrupter, separable contacts, an operating mechanism for said contacts, a solenoid having an armature movable to actuate said mechanism to separate the contacts in response to a predetermined value of cur rent, lockout means operable to hold said contacts separated, switch means operable in response to said lockout means to decrease the effective ampere turns of said solenoid, and releasable means for retaining said switch means operated when the temperature of the interrupter is below a predetermined value.

3. A circuit interrupter comprising, separable contacts, an operating mechanism for said contacts, electroresponu sive means having an armature movable in response to a current above a predetermined value to actuate said operating mechanism to effect separation of said contacts, lockout means actuated by a predetermined number of closely consecutive operations of said electroresponsive means to maintain said contacts separated, means operable to reduce the effectiveness ot the electroresponsive means actuated by operation of the lockout means, and releasable means operable in accordance with the temperature of the interrupter for maintaining the aforesaid means operated it the contacts are maintained separated for more than a predetermined time;

4. In a circuit interrupter, separable contacts, an operating mechanism therefor, electroresponsive means for actuating said mechanism to effect separation of said conv tacts in response to an overcu rent, lockout means actuated by a predetermined number of separations of said contacts operable to maintain said contacts separated in response to a predetermined number of closely consecu tive separations, recalibrating means actuated by operation of said lockout means to recali'orate said electroresponsive means and increase the value of overcurrent Y required to operate the electroresponsive means, and latch means operable in response to said contacts remaining open for a predetermined time to retain the recaiibrating i means operative when the contacts are closed.

l of the electroresponsive means in response to overcurrent conditions, recalibrating Ymeans operated by the lockout means when it operates to maintain said contacts separated to reduce the effectiveness of said electroresponsive means, biasing means for rendering the recalibrating means non-operative, and thermally responsive latch means for retaining the recalibrating means operated after the temperature of the interrupter reaches a predetermined minimum value.

6. in a circuit interruptor, separable contacts, an o'perating mechanism for said contacts, electroresponsive means operable to actuate said mechanism for separating said contacts, lockout means operated by a predetermined number of contact separations to maintain said contacts separated, recalibrating means operated by the lockout means when it acts to maintain separation of said contacts to reduce the effectiveness of the electroresponsive means, biasing means normally making the recaiibrating means inoperative when the contacts are closed, and thermoresponsive releasable means operable to retain the recalibrating means operative against the effect of said biasing means when the temperature of the interruptor reaches a value a predetermined amoun below the operating level.

7. In a circuit interrupter, separable contacts, operating means therefor including a solenoid having a movable armature for separating the contacts, lockout means operated by closely successive contact separations to maintain the contacts separated, switch means connected in circuit relation with the solenoid operable to reduce the effective ampere turns of the solenoid, actuating means operated by operation of the lockout means to eifect operation ot the switch means, biasing means normally' effective to open the switch means when said contacts are closed, and releasable means maintaining the switch means operated when the contacts remain open for greater than a predetermined time.

S. A circuit interrupter comprising, separable contacts, operating means for said contacts, electroresponsive means for actuating said operating means and separating said contacts including a solenoid having au armature responsive to a predetermined value of current, lockout means for biasing the operating means and maintaining the contacts separated, a counter having a member advanced by closely successive operations of the electroresponsive means to effect operation of the lockout means to eventually lock said contacts open, an impedance device, means including a switch actuated by the lockout means connecting the impedance device in circuit relation with the solenoid, and releasable means operable when the ternL erature of the interruptor mls below a predetermined temperature to maintain said switch in the actuated position.

9. in a circuit interrupter, separable contacts, means including a solenoid having an armature for electing separation of said contacts, lockout means for maintaining said contacts open, a counter operated by closely successive separations of said contacts to effect operation of the lockout means, a resistor, a switch, operating means operable in response to operation of the lockout means to eiiect operation of the switch to connect the resistor in circuit with the solenoid to reduce the effective ampere turns of the solenoid, said switch being normally disposed to open when the interrupter is closed, and a latch having a bimetallic member for retaining the switch closed when the temperature of the oil drops below a predetermined value while the interrupter is open.

1G. A circuit interrupter comprising, separable contacts, operating mechanism therefore, a solenoid having armature operable in response to a predetermined value of current to operate said mechanism to separate said contacts, said contacts being biased to reclose, lockout means operable to maintain said contacts separated against the reclosing bias, a counter operable in response to closely successive operations of the armature to effect operation of the lockout means, a resistor, a switch actuated by operation of' the counter to connect ythe re sistor in shunt with'at least a portion of the solenoid,

and latch means including a temperature responsive member retaining said switch closed, only if the interrupter remains open for sufficient time for the temperature thereof to fall below a predetermined level.

ll. A circuit interrupter comprising, separable contacts, an operating mechanism for said contacts, electroresponsive means for operating said mechanism and separating said contacts in response to a current above a predetermined value, a lockout mechanism for locking said contacts open, a counter operated by a predetermined number of closely successive operations of the electroresponsive means, a switch actuated by the lockout mechanism to reduce the effectiveness of the electroresponsive means, and a bimetallic latch for engaging a portion of the switch and retaining the switch actuated when the contacts are closed, provided the temperature of the interrupter has ldropped below a predetermined value.

l2. In a circuit interrupter, separable contacts, an operating mechanism for said contacts, electroresponsive means including a solenoid having an armature for opterating said mechanism and etecting separation of said contacts, lockout means for maintaining said contacts separated, a counter actuated by a plurality of contact yseparations to effect operation of the lockout means, a resistor, a switch actuated by the lockout means to connect the resistor in shunt with at least a portion of the solenoid, a bimetallic latch element for engaging a portion of and retaining the switch closed if the temperature of the interrupter is below a predetermined value, and a bimetallic element opposing said latch element compensate for changes in ambient temperature` l3. In a circuit interrupter, separable contacts, means including a solenoid having an armature movable to eiTect Separation of said contacts, a magnetic circuit for said solenoid including pole pieces of magnetic material, lockout means for maintaining said contacts separated, a counter operated by a predetermined number of closely successive separations to eifect operation of the lockout means, means shunting said solenoid including a switch having an armature of magnetic material extending between said pole pieces so as to be held closed for eX- cessive currents by magnetic attraction to at least one of the pole pieces, actuating means for closing said switch only when the lockout means operates, and latch means including a bimetallic element for holding the switch closed so iong as the temperature is below a predetermined level.

lfi.. A circuit interrupter comprising, a container having insulating oil therein, a cover for said container, separable contacts supported in said oil from said cover, means for separating said contacts including a solenoid supported from the cover in said container responsive to current above a predetermined value, means biasing said contact-s closed, lockout means operable to maintain said contacts separated, a counter actuated by closely successive separations ot" the contacts for operating the lockout means to maintain said contacts separated after a predetermined number of such operations, a. resistor, a switch connecting the resistor in shunt with the solenoid, actuating means for said switch operated by the lockout means, a spring biasing the switch open, and a latch having a bimetallic operating member mounted adjacent the solenoid disposed to engage and latch the switch closed when the temperature of the solenoid and oil falls a predetermined amount below a normal operating temperature.

References Cited in the tile of this patent UNITED STATES PATENTS 2,274,135 Frank et al Feb. 24, i942 2,349,632 May May 23, 1944 2,361,221 Ludwig et al. Oct. 24, 1944 2,468,498 Kyle et al Apr. 26, 1949 2,468,851 Wallace May 3, i949 2,655,575 Wallace et al. Oct. 13, 1953

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