US2680170A - Dashpot controlled circuit interrupter - Google Patents

Description

June 1954 J. M. WALLACE DASHPOT CONTROLLED CIRCUIT INTERRUPTER Filed March 50, 1950 2 Shets-Sheet l Fig.3.

FgJ.

INVENTOR James M. Wclloce:

ATTORNE J 1954 J. M. WALLACE 2,680,l70

DASHPOT CONTROLLED CIRCUIT INTERRUPTER Filed March 30, 1950 2 Sheets-Sheet 2 Fig.2.

WITNESSES:

INVENTOR James M Wollace.

Patented June l, 1954 DASHPOT CONTROLLED CIRCUIT IN TERRUPTER James M. Wallace, East McKeesport, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporat'ion of Pennsylvania Application March 30, 1950, Serial No. 152383 7 Claims.

This invention relates to electric circuit interrupters and particularly to such interrupters having a fluid dashpot or the like, for controlling operation of the interrupter.

This application is a continuation in part of the 'copending application of J. M. Wallace, Serial No. .542,681, filed June 29, 1944, now Patent No. 2,528,l97, October 31, 1950, on Circuit Interrupters, and assigned to the same `assignee as this application. The divisional part of this application illustrates how the invention is applied to one type of automatic reclosing circuit breaker, and in addition there is also illustrated herein the manner in which this invention is applied to a circuit breaker of the type shown in the copending application of J. M. Wallace et ai., Serial No. '719,524, filed December 31, 1946, now Pa'tent No. 2,626,329, January 20, 1953, on Circuit Interrupters, and also assigned to the same assignee as this application.

It is often desirable to impose delay on circuit opening operations of a circuit interrupting device, and in the case of an automatic reclosing circuit breaker, it may also 'be desirable to impose delay between an opening operation and the subsequent automatic closing, all for the purpose of Coordination with other circuit interrupters in the same circuit. One type of device which has desiraloly been employed for imposing time delay is a .fluid means, such as a dashpot, because of its mechanical simplioity. However, such a time -delay means has the characteristic of providing a time delay period which varies with temperature and viscosity of the fluid employed, so that proper coordination with other inter-' rupting devices is not always obtainable under conditions oi wide temperature'variations.

Accordingly, one object'of this invention is to provide a novel 'circuit interrupter having fluid means for controlling operation thereof which is not substantially affected by temperature variations.

'Another object of this invention is to provide an automatic reclosing circuit breaker with fluid means controlling both circuit opening and closing Operations thereof in a substantially uniform manner irrespective of temperature variations.

Another object of this invention is to provide in an automatic reclosing circuit breaker having fluid means which is rendered operative to delay operation of the breaker only in response to the occurrence of a predetermined number of closely successive Operations thereof, additional means for rendering said 'fluid means capable of imposing a substantially constant delay period, irrespective of temperature Variations.

Still another object of this invention is to provide temperature compensating means for circuit interrupters having fluid means controlling one or more Operations thereof.

These and other objects of this invention will become more apparent upon consideration of the following cletailed description of preferred embodiments thereof when taken in connection with the attached drawings, in which:

Figure 1 is a longitudinal -sectional View of a circuit breaker embodying this invention;

Fig. 2 is a longitudinal sectional viewof amodified form of circuit breaker which embodies a modified form of this invention;

.Fig. 3 is an enlarged plan `View of a part of the circuit breaker shown in Fig. 2; and

Fig. 4 is a cross-sectional view of a part shown in Fig. 3, taken substantially on the line IV-IV of Fig. 3.

The embocliment ;of the invention illustrated in Fig. 1 is included in a circuit breaker of the type shown in J. M. Wallace Patent No. 2,333,604, issued November 2, .1943, to the same assignee of this invention, and consequently reference is hereby made to this patent for a more complete description of the circuit breaker Construction and operation.

Generally, this type of automatic reclosing circuit breaker comprises, in general, atubular cas-` ing 2 of insulating material, such, for example, as porcelain or the like, which may be supported at a mici-portion thereof, for example by a supporting bracket i. The casing 2 illustrated, is provided with a closed lower end having an aperture for receiving a terminal bolt 6, having an enlarged head ll] positioned 'interiorly of the casing, and adapted to have a line conductor 3 secured thei-eto exteriorly of the casing.

The upper end of casing 2 is open, and is adapted to be closed by a terminal cover structure 12 having a flange adapted to be seated on the upper end of casing 2, and cover [2 may be Secured to the casing in any desired manner, such, for example, as by securing means (not shown) connecting the cover to a securing ring !3 fixed to the 'upper end of 'the casing. Cover [2 is preferably hollow and may be provided With a threaded filler plug I 4, and with a wire conneetor !5, for connection to another circuit conductor. Within hollow cover l 2 there is provided a supporting shaft E extending transversely thereof and mounted at its opposite ends in opposite walls 'of the hollow portion of the cover, for supporting a generally U-shaped spring support IS. Spring support !8 preferably has the leg portions thereof rotatably *mounted on shaft 16,

and a lockout spring 20 is coiled about shaft l, and has one end 22 thereof reacting against the bight portion of spring support !3, with the other end 24 thereof reacting against a part of cover !2, to bias spring support i& in a counterclockwise direction about the shaft 16. l-lowever, spring support l l is normally prevented from rotating counterclockwise on shaft !E by an overcenter toggle, comprising pivotally connected toggle levers 25 and 28 which are pivoted to spring support !8 and to cover 12, respectively. Toggle lever 28 is fixed on a rotatable shat 35. for pivotally mounting toggle lever 28 on the casing and toggle levers 26 and 23 are held at the overcenter position shown in full lines in Fig. 1, by an indicating handle 32 which is also rigidly mounted on shaft 30, and engages an adjustable stop screw 3@ mounted beneath a hood 35 integral with cover !2. The outer end of handle 32 is provided with a hook eye aperture 36, so that it may be actuated by a hook stick Operating member or the like.

shalt is within the hollow portion of cover iz also supports a reclosing spring 37 of smaller diameter and mounted within lockout spring 2%,

with one end 38 of this spring reacting against the b ight portion of spring support is, and with the other end M! of the reclosing spring reacting against an actuating lever 42 which is pivotally mounted on shalt l. The breaker Contacts are adapted to be actuated at least to Close the circuit by spring S'i and actuating lever 42, and for this purpose the lever is connected to a contact actuating rod 46, by means or" a pair or" connecting links t of insulating material, such, for example', as fiber or the like. Contact actuating rod 46 extends through casing 2, passing through a solenoid coil supporting frame 48 and into an are chamber 50 located adjacent the closed lower end of the casing. All of the parts within casing 2 are supported from cover !2, since coil supporting frame &18 is secured to the cover by spaced supporting posts 52 of insulating inaterial, such, for example, as fiber or the like, and are chamber 50 is supported from coil supporting rame ti! by spaced supporting plates ti (only one shown), which are Secured to rame 43 and to arc chamber 55. The lower end of arc chamber 59 is provided with a terminal cap 55 threadedly mounted thereon, and a coil compression spring 58 of conducting material, is adapted to be compressed between terminal cap 55 and head !El of terminal bolt (i, when cover !2 is assembled in operative position with the casing, to conduct current from terminal bolt 6 to terminal cap 56.

Arc chainber is preferably forrned by a tube of insulating material, such as fiber or the like, and has, in addition to terminal cap 56, an upper cap 62 threadedly mounted on the upper end thereof. Terminal cap 55 of the arc chamber is provided with a contact screw 84 substantially centrally thereof, and also has a plurality of inlet openings 555 adapted to be controlled by a valve ring 533 freely movable between terminal cap 55 and the adjacent end of tube te. Upper cap 62 for the arc chamber is provided with at least one outlet opening 12 adapted to be controlled by a valve plate 'i l inovable between the upper end of tube Sii and cap 52, but normally held at a position uncovering opening 12, by a coil compression. spring lt.

Contact actuating rod i& is provided with an end section 78 which extends through a central aperture in arc chamber cap 62, and section ta is provided with a sheath 80 of insulating material, such, for example, as a molded insulating material, for engagement with the aperture in cap 82. Section 'IS of the contact rod is provided with a contact head 82 at its outer end for engagement with fixed contact screw %4.

Because of the particular construction of arc chamber 50, when movable contact 32 is moved away from fixed contact 8 1 to strike an arc, such an arc will create pressure within the arc chamber such as to cause valve disk 63 and valve plate 'M to close both the inlet and outlet openings. Preferably casing 2 is filled with an arc extinguishing liquid, such as oil, up to the level L shown in Fig. 1, so that arc chamber 50 will be submerged in such liquid and will always be filled with liquid. Accordingly, an arc ormed within chamber 50 will cause deterioration of the arc extinguishing liquid, and form gases to further increase the pressure within the chamber. This pressure within the chamber acts on section 18 of the contact actuating rod, together with its sheath 80, in a pisten-like manner to aid in moving contact sa away from fixed contact 64, and may even cause overtravel of the movable contact with respect to its actuating mechanism. As soon as the arc is extinguished, pressure will drop within the arc chamber, and spring 16 will be operative to move valve plate 14 to a position uncovering outlet opening 72. This will per-mit the gas bubble formed within the arc chamber during arcing to escape from the upper end of the chamber, and the head of liquid outside the are chamber will cause Valve disk 68 to be displaced, thereby permitting fresh liquid to flow in through inlet openings 66. This provides an automatic fiushing of arc chamber 55) after each circuit interrupting operation, during reclosure of the breaker contacts by reclosing spring Bl.

In order to cause an initial separation of mov able contact 82 from fixed contact 64, which is at least suicient to establish an arc within the arc chamber, there is provided a solenoid coil 84 mounted within the supporting rame 48. This coil is annular in form, and is provided with a dashpot sleeve 86 which extends through the center of the coil, with the sleeve preferably being of an insulating material such, for example, as a molded insulating material. Dashpot sleeve 86 is held in engagement with a cup-shaped Washer member 961 reacting against the top of frame 48, by engagement of a cross frame member 88, which is integral with supporting plates 54. A tubular core 92, of any desired magnetic material such as iron or the like, is provided for coil 84, and the core is slidably mounted within dashpot sleeve 86 and has a close fit therein to act as a dashpot pisten. The lower end of core 92 is preferably closed and provided with a central aperture for closely slidably receiving contact actuating rod 45, and has vent apertures 93 through the side wall thereof adjacent the closed lower end. Core 92 is provided with an internal wear ring 94 adjacent the other end thereof having a close sliding fit With an enlarged portion 95 of an actuating sleeve 93 which is slidably mounted on contact actuating rod 45. Actuating sleeve 98 is provided with a fiange !GB at the upper end thereof above frame ili), for engagement with a shoulder oa on the contact actuating rod. A coil compression spring !532 reacts between the closed end of solenoid core 92 and the enlarged portion 953 of actuating sleeve 88, to bias the core to the lower position shown in Fig. 1.

In order to hold the contacts separated to prevent too rapid a reclosure thereof following a .circuit interrupting operation, contact actuating rod 46 has mounted thereon a transversely .ex- -tending supporting plate 104, and a latch plate 'I OS is pivotally mounted at one end on this supporting plate. Latch 'plate His is provided with an aperture for receiving contact actuating rod 46 which is large enough to permit pivotal movement of the latch plate, and with another aperture adjacent its mounting on supporting plate 104, for relatively closely receiving a latch rod !08 supported between frame 48 and cap '62. Latch rod me is provided at the lower endthereof with a portion Hil which is reduced in section, for a purpose to be described, and latch plate 106 is normally biased upwardly by a compression .spring 512.

The electrical circuit through the breaker illustrated in Fig. 1 extends from Connector |5 on cover !2, by way of a conductor I I 4 to solenoid coil 48, then by a flexible eonductor l 6 to contact actuating rod as, to fixed contact 64, conducting spring 58, then to terminal bolt 6 and line conductor 8. It is thus apparent that solenoid coil 64 is connected in series in the circuit through the breaker so that it will be responsive to Currents above a predetermined value to attract core 92 upwardly into the coil, while compressing spring !02. This movement of core 92 will be delayed due to the dashpot action thereof in dashpot sleeve 35, and will not cause separation of the contacts because spring !02 is considerably weaker than closing spring 37. When core 92 finally engages the lower end of actuating sleeve BE, the latter will be moved upwardly into engagement with shoulder ll on actuating rod 46, to cause separationof contact -82 from fixed contact 64. This establishes an arc in arc chamber 50, which is extinguished as previously eXplained, and due to the lost motion of core 92 on the contact actuating rod, pressure 'within the arc chamber may cause overtravel of contact 82 and contact actuating rod 4%, beyond the point to which it is moved by core 92. During opening move ment of contact 82, latch plate 106, which is carried up with contact actuating rod 46, slides over latch rod 238, and any 'tendenoy of latch plate !56 to bind on latch rod me is overcome by pivotal movement of the latch plate in a clockwise direction, while oompressing spring 2. However, as soon as the arc is extinguished and reclosing spring 3? attempts to move contact 82 towards fixed contact sa, latch plate 106 will bind on latch rod i ha due to counterclockwise rotation thereof under the influence of spring 2. In order to release latch plate !06, it is necessary to depress the free end of the plate to rotate it in a clockwise direction. This is 'done by solenoid core 92 during its return movement under 'the influence of gravity and compression spring !02. However, return movement of solenoid core 92 'is quite slow, because of the dashpot action of the core in sleeve 86, and consequently movable contact a will return substantially at the same speed as core 82, until latch plate !85 arrives at reduced portion t iii or latch rod 308 where it can `no longer bind on the latch rod, and at this point contact 82 will be rapidly moved into engagement with fixed contact 'M by reclosing spring 31. It should be noted that in a circuit opening operation, movement of solenoid core 92 upwardly is delayed by its dashpot action in sleeve 36 only until ring M reaches the upper end of enlarged portion 96 of the actuating sleeve. Thereafter liquid trapped in the upper end of the .sleeve 86 may escape through the core and its vent open- 3 extends across the open side ings 93, so that the final movement *of core ;92 into engagement with actuating sleeve .98 toseparate contact 82 from fixed contact 64 takes place rapidly, to obtain at least a predetermined separation of the contacts on each circuit interrupting operation at a relatively rapid rate.

Lockout means are ,provided for counting the number of closely successive circuit interrupting Operations, such as a lockout piston and cylind'er l l8 mounted on coil supporting frame 48, which is adapted to be actuated by a lockout pawl 120. The pawl 120 is tiltably and slidably mounted .on a guide rod ll, and is adapted to be actuated by flange IM on actuating sleeve 88 each time it moves upwardly during a circuit interrupting operation, to advance 'the lockout piston, until after a predetermined number of closely succeeding circuit interrupting Operations, the piston is finally advanced sufiiciently to 'engage toggle lever 23 adjacent the knee of the toggle 'to move the toggle levers overcenter, and thereby permit lockout spring 20 to rotate spring support 18 counterclockwise. This causes the bight portion of spring support Is to engage an extension H'9 on actuating lever 42 to also rotate the actuating lever counterclockwise and hold the breaker contacts in open circuit position. It will be observed that counterclockwise rotation of spring support l'8 removes the reaction point for end 33 of reclosing spring 31, so that this spring will be inoperative to reclose the contacts. When the toggle formed by levers 26 and 28 is moved overcenter and breaks, handle 32 rotates with lever 28 in a clockwise direction and extends 'below hood 35 to give a readily visible indication of the lockout condition of the breaker. The breaker will remain in a lockout position until manually reset 'by operation of handle 32 back to the position shown in Fig. l, wherein toggle levers 26 and 28 are moved back to the overcenter position shown, to prevent operation of lockout spring 20.

The parts of the breaker described thus far are substantially all more particularly disclosed in the aforementioned Wallace patent.

One diiculty with dashpot time delay means, especially those designed to operate in a liquid, such as oil, is the variation in time encountered with temperature variations due to the change in viscosity of the oil with such temperature changes. It is of particular importance in automatic reclosing circuit breakers that the time of operation, including both opening and reclosing of the Contacts, be a predetermined value which does not substantially vary, due to the necessity of coordinating such circuit breakers with 'other circuit interrupting apparatus, such as fuses and other circuit breakers having definite time -characteristics In order to improve the time characteristc of the dashpot time delay means described above, the upper end of dashpot sleeve 86 is provided with vents which are opened gradually in re-` sponse to a decrease in temperature and consequent increase in viscosity of the arc extinguishing fluid. For this purpose, a closure disk :35 is threaded into the upper end of coil supporting fram'e 48, and has threadedly mounted in a central aperture thereof, a plug 933 adapted -to be held in engagement with a shoulder provided in the upper end of frame 48. Plug 138 is provided with a plurality of channels .w communicating the upper end of sleeve with the space within cup Washer 296. Closure disk [36 of -cup washer 90 and is provided with vent apertures !42, communicating the space within cup Washer 90 with a space !44, provided within the upper end of rame 48. The space !44, in turn, opens to the interior of casng 2 by means of vent apertures !46, preferably aligned with the vent apertures !42. Both sets of vent apertures !42 and !49 are adapted to be controlled by a bimetal valve disk !48, mounted in space !44. Bimetal valve disk !48 is provided with a central aperture for freely receiving plug !38, so that the valve disk is reely movable to cover and uncover vent apertures !42 and !46. Bimetal valve disk !48 is constructed in a well-known manner of laminations !50 and !52 intimately Secured together as by welding or the like. Lamination !50 of the disk is of a material having a relatively high coefficient of thermal expansion, such as brass, and the other lamination !52 is of a material having a relatively lower thermal coeicient of expansion, so that at normal temperatures the disk !48 will be substantially fiat, as shown in Fig. 1, and will assume an upwardly ooncave shape upon lowering of the temperature. Valve disk !48 is positioned below the level of are extinguishing fluid within casing 2, so that it is responsive to the temperature of such liquid to more or less cover vent apertures !42 and !46.

During operation of the circuit breaker, if it be assumed that the arc extinguishing liquid is at a normal temperature so that valve disk !48 is in flat condition, as soon as solenoid core 92 moves upwardly, it will cause a fiow of fluid through vent apertures !42 and move valve disk !48 upwardly to cover vent apertures !46, and the rate of movement of core 92 will be governed by the rate of escape of fluid trapped in the upper end of dashpot sleeve 86 through the relatively small clearances between the core, sleeve 86, and enlarged sleeve portion 96. Now, if the temperature of liquid within c-asing 2 drops so that its vscosity increases, valve disk !48 will assume an upwardly concave curved shape, so that when core 92 moves upwardly, there will be an additional path opened for fluid to escape, through vent openings !42 and through the central opening in valve disk !48 and out vent openings !45, even though the valve disk be moved up by the flow of fluid outwardly into engagement with the upper wall of space !44. Similarly, upon return movement of core 92, valve disk Me will be drawn down to cover vent openings !42 if the valve disk is in a fiat condition, but if it is curved, an additional path for the flow of fluid into the upper end of dashpot sleeve 85 will be provided through vent openings !46, and around the outside edge of the valve disk and through vent openings !42 and channels !40 into the dashpot sleeve, to there-' by compensate, both during circuit opening and circuit closing, for any increase in visccsity of the arc extinguishing liquid, by increasing the openings for inlow and outfiow of liquid with respect to dashpot sleeve 86.

The modification shown in Figs. 2 to 4 is illustrated in connection with a circuit breaker of the general type disclosed in the aforesaid Wallace et al. application, which is mounted in a metal tank 54! having a closed bottom wall and an open top. Preferably, the tank is adapted to be lined at least over the bottom wall and u to a point adjacent the open top of the container with a liner !43 of insulating material such as fiber, or the like, and is adapted to be filled with an insul'ating liquid, preferably a liquid having arc ex'- tinguishing ability,'such as oil or the like up to the level L. The upper end of tank !4! is provided with an outwardly extending fiange !45 on which the flange !41 of a cover casting !49 is adapted to be seated, preferably, with a gasket 15! interposed therebetween. Flange !45 of cover casting !49 may be provided with an integral lip !53, and the cover may be Secured to the tank in any desired manner, such for example, as by bolts (not shown) extending through openings in cover flange !41 and Secured to suitably formed brackets on the tank.

The breaker contacts and certain of the contact actuating mechanism are adaptecl to be supported in tank 2 from cover casting !49 by means of a pair of integral supporting lugs !54 (only one shown) depending from the top wall of the cover casting and each is adapted to be Secured to a spacer rod !56 of insulating material which in turn is Secured to a supporting casting !58. A supporting plate !60 may be supported in a similar manner from casting !58, so that a solenoid coil 62 may be mounted between casting !58 and supporting plate !60, with the central opening in the coil aligned with openings provided in casting !53 and plate !60.

Spaced stationary contacts !64 of the breaker are each supported from plate !60 by supports !66 of insulating material, such as fiber, formed in a U shape, with the stationary contacts being mounted in openings provided in the base portions !68 of each support !66, and with the upper ends of each support !66 having laterally extending anges !19 by means of which each support is Secured to supporting plate !30. As illustrated, each contact !64 is formed as the head of a bolt to which a conductor may be Secured, as by the nuts !12.

stationary contacts !54 are adapted to be closed by engagement therewith of a bridging contact l '14 having contact tips !16 at opposite ends thereof for engagement with the stationary contacts, respectively. Bridging contact !74 is supported substantially centrally thereof on slidable contact actuating rod !78 by a pivot pin sc for limited pivotal movement about a transverse axs. Contact rod !78 being mounted for longitudinal sliding movement through coil !62 and the aligned openings in plate !69 and casting !58, it will be observed that bridging contact !14 is free to adjust itself to the stationary contacts by restricted pivotal movement about its pivotal mounting !80. Contact rod !18 should be of an insulating material such as fiber or a molded insulating material.

The upper end of contact actuating rod !18 has a pair of eonnecting links !82 positioned at each side thereof and pivoted thereon as by a pivot pin !84, with the upper ends of these connecting links mounted on a common pivot pin !SG for a pair of toggle levers :89 and E 90. Toggle levers !88 and !99 are both formed of sheet material, with lever !88 bent to substantially channel form with outwardly extending flanges !92 adapted to be received at the free end thereof in recesses !94 provided in the spaced down- Wardly depending fingers of an angled supporting bracket !96 which, in turn, is Secured as by a screw !98 to a lug 299 integral with the cover casting. Preferably, the base of the channel part of toggle lever !88 is extended as at 282 through the space between the supporting fingers of bracket !96, and at the other end of lever !88 the sides of the channel formation thereof are extended to be mounted on pivot pin !86. A coil tension spring 204 has one end hooked into an' 9 opening' provided in to'ggle lever !90, and'has'the opposite end thereof hooked over an integral spring support (not shown) on the cover casting. It will be observed that' in the closed circuit position of the br'eaker illustrated in Fi 2 of the drawings, the line of action of toggle spring 20&

appr'oach that pivot point so' that in response toa very small contact separation the line of action of toggle spring ZM will pass through pivot recesses !94 which is the omcenter position of the resilient toggle a'rrangement comprising toggle levers" !88` and !96 and togglespring 204. As apractical matter, the opening movement of the contacts'necessary to move toggle levers !88 and !ISO to the on-center position mentioned above may be made very small, in oneoperative-device being'on the order of one-quarter of an inch. When toggle levers ISS; and !60 reach-their' oncenter position referred to above; further relative movement of the two toggle levers in the same direction is prevented because' the upper edgeof toggle lever' 99 engages' the base of the central channel formation of toggle lever !88. Moreover, since the point at which toggle spring ZM is hooked into' lever i 90 then substantially coin'cides with recesses !94 in whichtoggle lever !88 pivots during contact opening movement, it will be apparent that the remainder and major' part of contact opening movement will occur substantially uninfiuenced by toggle spring' 204; Substantially the reverse of the above operation occurs' when contact' Operating rod !78 moves downwardly to close the circuit from the full open contact position, because during the first and major part of contact closing movement levers !83 and* !90 will be in engagement so that such movement will' be uninfluenced by toggle spring 204'. However, as soon as pivot !86 passes" below a line drawn from' th'e'remote end oftoggle spring 2'84 through pivot recesses !94 for link ist, toggle spring 204 will then be effective to move the toggle levers' toward the position shown in Fig. 2, and the force exerted by toggle spring %i thus tending to close the Contacts will continue to increaseas toggle levers !Bilanci !90 move further away from their On-Center positions.

Solenoid coil !62 previously mention'ed is' a'dapted to be energized under certain' condi tions for'automatically opening the circuit'break-' er Contacts. The central opening through coil !62 preferably is provided' with a cylindric'al sleeve 296 in'- which a solenoid core 268 is adapted to b'e slidably mounted in a piston-like manner. Core 208 is in the form of a cylindrical' sleeve having opposed slots 2!'G in the-upper'portions' thereof adapted in the normal closed circuit position of the device illustrated to extend' partly above and' partly below supporting plate 169, by engagement of an exterior shoulder adjacent the'` upper end of the core with a sleeve 2!2 'which has anex-' ternal rib held between the sleeve 206 for the coil and supporting plate see; The lower' end of core` 208 is provided with opposed holes 2 !4, for a purpose to be hereinafter described.

A contact actuating sleeve!! 6 is telescoped over contact actuating rod !78' and its lower end is received in core 208 and threadably mounted the'rin. A coil compression spring 2!'8 is provided within actuating sleeve 2 i ii on contact actuating rod :te and is adapted to react between an inner shoulder in the core pin *228 extendingtransversely through actuating rodl'ia.

The circuit through the circuit breaker thus far described may now be traeed from the point where it enters tank !M through one of a pair of terminal bushings 222- (only one being shown), with each bushing Secured to cover casting ME! as by bolts 22 5, and each being provided with a terminal fixture 225 at the upper end thereof mounted on a conductor element which extends through the bushing and emerges from a re"- duced extension 223 of the bushing seated in an opening provided in the top wall of cover casting !48, and proceedsby conductor 2353 directly to one fixed contact !64 oi' the'breaker. When the Contacts are in engagement, the circuit then p'roceeds through bridging contact !14 to the other fixed contact !64, and then by way of a conductor 232' to one terminal of solenoid coil !62. The other terminal of coil !62 is adapted to be connected by a conductor 234' to the conducting means in the other terminal bushing 222. It will be apparent that solenoid' coil !62 in this embodiment of 'the invention' is connected in v series in the circuit through the circuit breaker so as to be energized at all times dependent upon the value of the load current flowing in the circuit;

For any given rating of* circuit breaker, so1e-' noidcoil !62 is designed to become suiciently energized when' the load current in the' circuit exceeds its rating as to attract core 208 and move it upwardly. Assuming the upper end of sleeve 206 to be' closed` except for the small clearance between sleeve 2l6 and casting !58, so that substantially no fiuid can escape, core 288 will move upwardly relatively rapidly until the bottom of slot Zlii reaches sleeve 2!2, whereupon there is no longer any vent for fluid contained in cylindrical sleeve 206, and it then' becomes' necessary upon further upward movement of core 208 to displace the liquid in sleeve 286 above the core through the relatively' small clearan'ce between the core' and sleeves 212 and 2!6 and between sleeve 2|6 and casting !58. Accordingly, opening movement of the core will be slowed up by the aforesaid dashpot action an amount determined by the current value of the overload, and, therefore, an inverse time-current characteristic on opening is obtained. This is due to the fact that the force exerted on core 208 by coil !62 will vary substantially directly in accordance with the value of overloa'd current, and consequently the greater force exe'rted on higher Currents will result in less time delay than on lower values of overload currents. Finally, when the upper ends of holes Zl i clear' the upper edge of sleeve 2 !2, core 208 will no longer be restrained by the dashpot action because fluid may then relatively freely escape, and the final opening movement thereof may be relatively rapid. As soon as core 208 commences its upward' travel; bridging contact !74` being held engaged by toggle spring 204 does not has substantially no value at all, so that the remaining major part of the circuit opening movement of the bridgng contact !14 is easily efiected by expansion of spring 2 !8. However, fiange 236 is provided to obtain a positive contact separation in the event there is any sticking or welding of the bridging contact to stationary contacts !64. In either case, it is apparent that toggle levers !88 and !90 will be moved to their on-center position in the manner previously described, and bridgng contact !14 will be moved by spring 2!8 to its full open circuit position. When the contacts separate and an arc is struck, with the resultant pressure developed thereby in the region beneath core 208, it will be observed that Washer 238 will be moved upwardly to seat on the lower end of core 208 to close off the clearance space between core 288 and rod !18 and thus prevent gases and other contaminating elements developed by the arc from entering dashpot sleeve 206.

When the breaker contacts have attained their full open circuit position, the parts associated therewith are biased to return by gravity. This closing bias is relatively light and will be immediately opposed by the dashpot action of core 200. Accordingly, the return movement will be relatively slow until pivot point !86 moves below the line of action of toggle spring 204 when toggle levers !88 and !90 are in engagement, whereupon bridging contact !14 will be rapidly moved to effect a snap-action closing of the breaker contacts by toggle spring 204. Moreover, at about this same time the lower ends of slots 2 in core 208 will clear the lower edge of sleeve 2!2 so as to vent the dashpot comprising sleeve 206 and core 208.

In order to provide means for maintaining the breaker Contacts separated and to also provide for manual operation thereof, spring means are provided for holding the breaker Contacts open, which means can be manually actuated. This means comprises a toggle lever 240 having a slot 242 at one end thereof for receiving a pin 244 mounted between spaced supporting arms 246 integral with cover casting !40. The other end of toggle lever 240 is pivoted, as by a pivot pin 248, to the adjacent end of a second toggle lever 250, and this, in turn, is mounted on a pivot pin 252 intermediate its ends, with the pin 252 mounted on the adj acent wall of cover casting !48. A slot 254 is provided through the cover casting !49 for receiving the other end of toggle lever 250 which acts as a manual Operating handle at the exterior of the circuit breaker casing, being provided with a hook eye 256 in its outer end. A coil compression spring 258 is mounted on toggle lever 240 and reacts between washers mounted on the toggle lever, one of which engages supporting pin 244, and the other of which engages a shoulder located acljacent pivot 248. Normally, toggle levers 240 and 250 are held with pivot 248 below the center line connecting pins 244 and' 252, with the outer end of lever 250 positioned in and beneath an integral hood 25! on cover casting !48, in engagement with an adjustable stop screw 260 mounted in the hood.

In the position of toggle levers 240 and 250 illustrated, they have no effect on operation of the circuit breaker as previously described, being normally inactive in this respect. However, the common pivot pin 248 of toggle levers 240 and 250 is extended at one side toward toggle levers !88 and !90 and in the normal position of the parts extends beneath the adjacent fiange !92 of toggle lever !88. Accordingly, if it is desired to manually open the circuit breaker Contacts, a hook stick or similar Operating member may be inserted in hook eye 256 of toggle lever 250 and pulled downwardly to rotate the toggle lever in a counterclockwise direction about its supporting pivot 252 to move toggle levers 240 and 250 overcenter in an upward direction, and in doing this, the common pivot pin 248 engages the adjacent flange !92 of toggle lever !88 and moves it upwardly in a counterclockwise direction, thus carrying contact actuating rod !18 with it to separate bridging contact !14 from stationary contacts !64. The contacts will be held open by spring 258 which maintains toggle levers 240 and 250 in their upper overcenter position. In thus manually opening the circuit after toggle spring 204 is moved to its on-center position, it will be observed that the spring 258 of toggle lever !04 is only required to maintain the Contacts of the breaker open against the relatively light closing bias due to gravity. 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 250 projects below hood 25! of cover casting !49 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 250 in the opposite direction, that is, by exerting an upward force on the outer end of the toggle lever to rotate it in a clockwise direction to move it and toggle lever 240 back overcenter to the position illustrated in the drawings. This manual operation of toggle lever 250 does not directly close the breaker oontacts but merely permits closure of the contacts in the manner previously described.

An integrating mechanism for automatically moving toggle levers 240 and 250 upwardly overcenter and thus preventing reclosure of the circuit breaker only in response to a predetermined number of closely successive circuit interrupting Operations, and at the same time for automatically controlling the circuit opening and closing times in a predetermined manner in any sequence of a plurality of closely successive circuit opening Operations, is provided comprising a cylindrical tube 259 is clamped in a lateral extension of casting !58 at the top of solenoid coil !62, and this tube has a plug 262 threaded into the lower end thereof with the plug having a small central opening controlled by a ball-check valve 264, which permits flow of fluid into the lower end of tube 259 but prevents outfiow. An integrating pisten 266 is mounted in tube 259 and normally rests on the upper end of plug 262, being provided with a reduced extension 283 at the upper end thereof, having a plurality of spaced circular flanges 210 forming rack teeth thereon, and having an elongated insulating extension 212 on the extreme outer end thereof which is positioned below an extension 214 on toggle lever 240. A pawl lever 216 is pivotally mounted at one end as at 218, with this end of pawl lever 216 being splt with legs located at each side of tube 259 and with pivot 218 supported on spaced supporting anges 280 integral with casting !58.

Pawl lever 218 has a connecting web intermediate its ends, and at the other end thereof the sides of the lever are extended outwardly and laterally as at 282, to normally be in engagement with a Washer 284 mounted on actuat- 1-3 ing sleeve 2| 6 in engagement with a shoulderadjacent the outer end of this tube. Pawl lever 216 is normally biased into engagement with Washer 284 by a coil tension spring 286 hooked over the remote. edge of the Web of the pawl lever at one end and" anchored to an ear integral with casting !5.8 at. its other end; Pawl lever` 216 is provided with a. paWl member 288 pivoted there on` as at 290.', and biased by a spring 232 in a` counterclockwise direction to a positionwherein a portion of pawl member engages the. connect'- ing web of pawl lever 216.

In order to. control the opening and closing times of the circuit breaker Contacts to. provide for different opening and closing times on prede-termined circuit opening and closing operations in any sequence of closely successivo operations, as on continuing overloads, the dashpot ormed by sleeve 2,06' and solenoid core 206 has a vent 294 at the uper Ll'ld thereof which is annular in form being provided in casting [58 about actuating sleeve 2l6. Annular vent 204 eommunicates `with a latterally extending passage: 296 also formed in casting I 58', so that,

fluid may escape from the upper end of sleeve 20.6 through annulavent 294' and passage 296, and then through. a pair of. opposed openings 298 in tube 250 from whence it may escape through a discharge opening 300, also forned in casting l58.. Theopenings 238 in integrator tube 259 are aligned with passage 296 and discharge opening 300.

In order to compensate for the efiect of temperature changes on the action of the fluid time delay means in this embodiment of the invention, passage 296 in casting [58 is provided with a tapped' opening (Fig. 4) adapted to receive a plug 302 containing a thermal valve arrangement. The plug 302 has a reduced threaded extension 304 adapted to be threadedly received in the tapped opening of casting [58. The reduced inner end of plug 3552 has a central passage formed therethrough for receiving a check valve member in the form of a rivet 300 having a head 3I3 adapted tobe seated on an internal shoulder formed in the reduced extension 304 of the plug. Check valve member 368 has a small` central' passage sis fcrmed therethrough for a purpose: to be described; The ou ter enlarged end 306: of. plug 302 is internally threaded for threadedly receiving a partition disk 312 which is threaded into engagement with an internal shoulder formed` in the enlarged outer end 306. Partition 3l2 is formed With diame trically opposed. outlet openings 3i4, and the passage of fluid through these, openings is controlled. by a valve disk 3l6 mounted beneath partition 3 I 2, and having a plurality of openings including relatively small openings 3|8- at diametrically opposed positions, and large openings 3'10 of substantially the sam size as outlet openings 354 in the partition, and also located at diametrically opposed positions With all of the openings in valve 316 located on the circumference of the same circle as openings 314 in partition 312, and with such circle having its center on -the central axis of` plug 302. Valve disk 316 is mounted for rotation by means of a valve stern 322 Secured centrally thereof and projecting through an opening in partition 3l2 to have Secured at its outer end one end of a spiral bimetal element 324, the other end of which is secured to a stationary post 326 securecl in partition 312.

With the parts of the circuit breaker at their normal positions. illustrated in Fig. 2, i-t will be apparent that when the circuit breaker operates to open the circuit, the upper. endof dashpot sleeve 200 being open. through annular vent 2:94; passage 296, openings 268 and discharge opening 360, that solenoid cor 206 will be moved very rapidly upwardly since the liqud in dashpot sleeve 206 above the coremay be freely' vented through the vent passages mentioned above, and consequently the initial circuit opening: operation of the breaker will occu` substantially in.- stantaneously. As solenoid core '16 moves up.- wardly, Washer 284 will be carried upwardly with actuating sleeve 2i6 and' thus carry the free: end of pawl.- lever 216. upwardly with` it to move pawl member 283 into engagement with. the upper one of fianges 270 on integrating piston 266, to thus carry the piston upwardly a predetermined clstance throughout opening movement of sleeve 216, and due to interlockng of the pawl lever and fiange 270, no overtravel of piston 266' is possible. Integrating piston 266 is not, however, carried upwardly a distance sufiicient to entirely remove reduced portion 268' thereof from between openings 225 in cylinder 258, so that the vent passageway from the upper end of dashpot cylinder 206 will not be blocked off by integrating piston 266. When. the breaker recloses following such a first circuit interrupting operation, such reclosu'e will also occur extremely* rapid ly because core 208 does not' have any dashpot action in its dashpot sleeve 200 due to theuppervent for the sleeve still being open. Accordingly, the first opening and reclosing of the circuit breaker Contacts will both occur substantially instantaneously with no time delay interposed due` to the dashpot action of core 208 in dashpot sleeve 206. During reclosing of th breaker the first time, integrating piston 266 is left at the position to which it was advanced, since pawl member 288 is free to disengage the. circular fianges 27 0, and if the breaker remains closed, integrator piston 266 will slowly reset to the position shown, this resetting movement being relatively slow due to the necessity of. displacing liquid drawn into the lower end of cylinder 253` by advancement of piston 266 during the opening operation, past the relatively small clearance between cylinder 258 and, piston 266. This means; of course, that if an overload appears on the-circuit at a later time', the breaker contacts will then be substantia-lly instantaneously opened and closed in the inanner described above. However, if the breaier* immediately reopens after a first opening and reclosing operation, pawl member 200 this time will engage the next lower circular fiange 210 on the integrator piston 266 and raise the piston a further amount sufiieient to bring the piston between side openings 263 in integrator cylinder 268 so that the integrator piston acts as a valve to close ofi the vent passage 266 from the upper end of dashpot cylinder 206'. Inasmuch as the integrator piston 266, does not close the vent passag until core 200 is substantially at the end of its circuit opening movement at which time the core vents dashpot sleeve 206, this seccnd closely successive circuit opening operation will, like the first, occur substantially instantaneously with substantially no delay due to dashpot cylinder 206 and core 208., However, on the succeeding reclosing operation, integrator piston 266 having closed the vent at the top of: dashpot cylinder 206, this reclosing operation will be delayed in the mannepreviousl'y de.- scribed by the dashpot action of core 208111 oylinder 206.

' This second reclosing operation will result in leaving piston 256 at the further advanced position described above, from which it eventually will reset in the manner previously described if the breaker remains closed, so that an overload appearing on the circuit at a later time will result in th breaker Operating in the manner described above for the first and second closely succeeding circuit opening and closing operation. However, in the event the overload continues after the second closely succeeding circuit opening and closing operations, the breaker will again open, and this time the opening operation will be delayed by the dashpot action of core 208 in dashpot sleeve 206, since integrator piston 206 has not had time to recede from the position to which it Was advanced on the second opening operation of this series of closely succeeding circuit opening operations, where it blocks the vent passage from the upper end of dashpot sleeve 206. A vent opening 200 is preferably provided in cylinder 259 to prevent fluid being forced through the clearance space between piston 206 and cylinder 259 and into the bottom of cylinder 259 beneath piston 200 during a time delay circuit opening operation, and thereby preventing undesired advancement of piston 266 at such time. The circuit closing operation of the breaker following the third opening will be delayed in the manner previously described, inasmuch as such third opening operation results in further advance of integrator piston 265 where it still blocks th vent passageway from the upper end of dashpot sleeve 206 The breaker may then continue to open and reclcse if the overload continues, with each opening and closing being delayed by the dashpot action of core 208 in dashpot sleeve 206 until finally pawl member 288 advances integrator piston 206 an amount sufficient to cause the upper extension 212 thereof to engage the extension 2l i of toggle lever 240 and move this lever upwardly overcenter so that toggle spring 258 will maintain the Contacts separated in the manner previously described. It is thus apparent that toggle levers 200 and 250 will be automatically moved upwardly over-center to maintain the breaker Contacts separated only in response to a predetermined number of closely successive circuit opening 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 contac-ts will be automatically held open only when the predetermined number of opening and closing operations occurs in close succession. Obviously, after the breaker contacts have been automatically actuated to a position where they are held open-by toggle spring 258, they can be reclosed only by manual operation of -toggle lever 250 in the manner previously described.

When the breaker contacts are held open inthe manner described above, it will be apparent that integrator piston 286 is held at its uppermost position by pawl lever 216 which is held at its upper position by actuating sleeve 2l'6. Accordingly, when the breaker is manually reclosed, the first inrush of current may be of a value in excess of the rating of the breaker, but since this current is due mainly to the sum of the starting currents of apparatus connected on the circuit, it will be of short duration and it is not desirable that the breaker should open on such initial high currents. Accordingly, it will be observed that 'when the breaker is manually closed following automatic operation to be held open, integrator piston 260 will be at a position where it blocks the vent passage from the upper end of dashpot sleeve 208, so that any attempted opening operation of the breaker will be delayed by the dashpot action of core 203 in dashpot sleeve 206. This clelay is long enough to permit the high value of starting currents encountered on reclosing the circuit to be dissipated, so that solenoid core 208 will reset before it has moved upwardly far enough to cause the breaker contact to open. Integrator piston 268 will also gradually reset and eventually be restored to the position shown in Fig. 2, so that when an overload comes on the circuit at a later time, it can operate in the manner described above to permit the circuit breaker to open and close the circuit, the same predetermined number of times before the breaker contacts are maintained open, and it will control the times of predetermined circuit opening and closing operations in any such sequence of closely succeeding opening and closing operations in the same manner. In the preferred sequence of operations leading to the breaker contacts maintained in open circuit position mentioned above, that is, a sequence of four operations in number, it will be apparent that with the apparatus described above, the first two opening operations will occur substantially instantaneously and the second two opening operations will be delayed with an inverse time-curent characteristic due to the dashpot action of core 208 in dashpot sleeve 206. Moreover, the reclosing times in any such sequence of four closely successive opening and closing operations will comprise a first substantially instantaneous closing operation with the remaining circuit closing operations being delayed by the dashpot action of core 208 in dashpot sleeve 206. The only time that the first circuit opening is delayed is when such an operation occurs immediately following manual reclosirg of the Contacts after they have been automatically held open.

A protective gap device 30! of the expulsion type may be provided to prevent operation of the breaker on voltage surges, with the outer tube of the protective device mounted intermediate its ends on an extension 3!! of supporting plate !60 at the underside of solenoid coil 162, being Secured thereto as by nuts threaded on the arrester tube. One terminal of the protective device may be connected with conductor 232 and one terminal of solenoid coil !62, with the other terminal of the protective device (not shown) connected with the other terminal of coil 152 and eonductor 234. This protective device and its particular manner of mounting and connection with this type of apparatus is more particularly disclosed and claimed in the copending application of H. L. Rawlins and J. M. Wallace, Serial No. 694374 on Overvoltage Protective Devices, filed August 30, 1946, now Patent No. 2,550,124, Apr. 24, 1951, and assigned to the same assignees of this invention.

It Will be observed that the thermally operated valve shown in Figs. 3 and l operates in a manner somewhat similar to that shown in the embodiment of the invention illustrated in Fig. l in that it controls a vent passage for the dashpot controlling circuit opening and closing operation of the circuit breaker When the valve formed by integrator piston 2 65 is in its closed position where the dashpot becomes effective to perform its delaying functions. Thus, the thermal valve shown in Figs. 3 and 4 includes a valve member 3l6 -which is loosely mounted so that when dashpot piston core 208 rises during a circuit opening operation valve disk 355 will be forced into engagement with partition 3l2 to thus seal of the' outlet openings 3l i in the partition (assuming a relatively high temperature with the valve positioned by binetal element 324 as shown in Figs. 3 and 4:). During a circuit opening operation, check valve rivet 303 cannot exert any fluid restriction because any tendency to do so would result in movement of this member upwardly to unseat its head from the shoulder inside reduced extension 304 of plug 302. However, when dashpot piston core 208 descends during a circuit closing operation, valve disk 316 will be moved back to the position shown in Fig. 4 where outlet openings sm in partition 312 are uncovered, and check valve 308 will then settle down to seat its head on the internal shoulder in extension 364 of the plug so that the rate of closing movement will be deterrnined by the size of passage 316, which in turn will determine the rate of flow of fluid into dashpot sleeve 206. Bimetal element 324 is, like element MS shown in Fig. l, formed of a strip of laminated material, with the lamination having the greater coeflicient of expansion arranged at the outside of the spiral formation. It will be apparent then that upon the occurrence of lower temperatures of the fluid in tank i ii, bimetal element 324 will act to rotate valve disk 316 in a clockwise direction as viewed in Fig. 3, to first align small openings 3 I& with outlet openings i i in partition sia, and as the temperature further decreases to ultimately align one or both pairs of large openings 32@ with the outlet openngs am to thus compensate for the increased viscosity of the fluid accompanying such lowered temperatures.

From the foregoing it is believed apparent that there is disclosed herein two modifications of means for rendering two forms of circuit breakers employing fluid time delay means substantially constant in their timing periods, irrespective of variations in temperature. It will thus be apparent that these fluid controlled circuit breakers can thus be more readily made to coordinate with other circuit opening means connected in the same circuit with them which have time characteristics substantially unaffected by temperature variations. Both forms of the particular temperature compensating means disclosed herein are arranged so that they are exposed to the fluid contained within the cirouit breaker casing, which fluid is also employed to assist in extinguishing 'the arcs formed when the circuit breakers open. Moreover, both forms of temperature compensation employ check valve like members operated by pressures developed in fluid dashpots to control vent openings from the dashpot, with the extent of such control being determined by the extent of deformation of a birnetal Construction. In the embodiment of the invention shown in Fig. 1, the temperature compensation applies to both circuit opening and circuit closing Operations, whereas that shown in Figs. 2 to l applies only to the circuit opening operation, because it is the time delay imposed on this operation which is most important in obtaining proper Coordination with other circuit opening apparatus.

Having described preferred embodiments of the invention in accordance with the patent statutes, it is desired that the invention be not limited to these particular constructions, inasmuch as it will be apparent, particularly to persons skilled in the art, that many modifications and changes may be made in these structures without departing from the broad spirit and scope of this invention. For example, the particular fluid control means disclosed may be employed with still other forms of circuit breakers. Accordingly it is desired that this invention be interpreted as broadly as permitted by the prior art.

I claim as my invention:

1. In an automatic reclosing circuit breaker, casing adapted to contain an aro extinguishing fluid, separable contacts in said casing, electromagnetic means in said casing for separating said contacts to interrupt the circuit in response to a predetermined electrical condition of the circuit, means for automatically reclosing said contacts in response to a circuit interrupting operation, fluid time delay means utilizing said arc extinguishing fluid for controlling movement of said contacts, said time delay means including an enclosure having a vent at one end and variable vent means including temperature responsive means providing the vent of said time delay means with a variable orice oflering substantially the same resistance to movement at all temperatures.

2. In an automatic reclosing circuit breaker, a container for an arc extinguishing fluid, separable contacts disposed in said container, means in said container for separating said contacts to interrupt the circuit in response to a predetermined electrical condition of the circuit, means for automatically reclosing said contacts in response to a circuit interrupting operation, fluid dashpot. means utilizing said arc extinguishing fluid for controlling operation of said contacts, said dashpot means having at least one vent opening located beneath the level of said fluid, check valve means movable into engagement with said vent opening by fluid displaced by said dashpot means during a circuit opening operation and movable away from said vent opening by fluid attempting to enter said dashpot means during a circuit closing operation, including a bimetal element res onsive to temperature conditions so that said valve means is movable in a different direction responsive to the temperature of said fluid to vary the extent it covers the vent opening during a circuit opening operation.

3. In an automatic reclosing circuit breaker, a casing adapted to contain an arc extinguishing fluid, separable contacts located in said casing, means in said casing for separating said contacts to interrupt the circuit in response to a predetermined electrical condition of the circuit, means for automatically reclosing said contacts response to a circuit interrupting operation, fluid dashpot means utilizing said arc extinguishing fluid for controlling operation of said contacts, said dashpot means including an enclosure having at least one vent opening adjacent one end thereof and located beneath the level of said fluid, check valve means movable into engagement with said vent opening by fluid displaced by said dashpot means during a circuit opening operation and movable away from said vent opening by fluid attempting to enter said dashpot means during a circuit closing operation, said valve means being movable in a different direction to vary the extent it covers the vent opening during a circuit opening operation, and bimetal actuating means responsive to the temperature of said fluid for moving said valve means in said diflerent direction.

i. In an automatic reclosing circuit breaker, a casing adapted to contain an arc extinguishing fluid, separable contacts in said casing, electro responsive means in said casing having a movable armature for separatng said contacts to interrupt the circuit in responsive to a predetermined electrical condition of the circuit, means or automatically reclosing said contacts in response to a circuit interrupting operation, fluid dashpot means including said armature and utilizing said arc extinguishing fluid for controlling operation of said contacts, said dashpot means having vent means comprising opposed inner and outer openings located beneath the level of said fluid, check valve means novable into engagement with said outer vent opening by fluid displaced by said dashpot means during a circuit opening operation and away from said inner vent opening, and movable away from said outer vent opening by fluid attempting to enter said dashpot means during a circuit closing operation and into engagement With said inner vent opening, said check valve means including a temperature responsive element so that at least the part of said valve means engageable with said outer vent openings is movable in a different direction in response to the temperature of said fluid to vary the extent it covers the vent opening during a circuit opening operation.

5. In an automatic reclosing circuit breaker, a casing adapted to contain an arc extinguishing fluid, separable contacts in said fluid, means in said casing for separatng said contacts to interrupt the circuit in response to a predetermined electrical condition of the circuit, means for automatically reclosing said contacts in response to a circuit interrupting operation, fluid dashpot means utilizing said arc extinguishing fluid for controlling operation of said contacts, said dashpot means having vent means comprising opposed inner and outer openings located beneath the level of said fluid, check valve means movable into engagement with said outer vent opening by i fluid displaced by said dashpot means during a circuit opening operation and away from said inner vent opening, and movable away :from said outer vent opening by fluid attempting to enter said dashpot means during a circuit closing operation and into engagement With said inner vent opening, and a bimetal element connected to said valve means to move it in a different direction in response to the temperature of said fluid to vary the extent it covers the vent opening during a circuit opening operation.

6. In an automatic reclosing circuit breaker, an arc space adapted to be filled With an arc extinguishing fluid, separable contacts adapted When separated to draw an arc in said space, means for separating said contacts to interrupt the circuit in response to a predetermined electrical condition of the circuit, means for automatically reclosing said contacts in response to a crcuit interrupting operation, fluid dashpot means utilizing said arc extinguishing fluid for controlling operation of said contacts, said dashpot means having a pair O separate vent means located beneath the level of said fluid, a normally open valve for one of said vent means, means for counting the number of Operations of said breaker which occur in close succession, means operated by said counting means or closing said normally open valve after a predetermined number of operations of the breaker in close succession, and a thermally responsive valve member for the other vent means to vary the flow of fluid therethrough in accordance with the temperature of said fluid.

7. In an automatic reclosing circuit breaker, an arc space adapted to be filled with an arc eXtinguishing fluid, separable contacts adapted when separated to draw an arc in said space, means for separatng said contacts to interrupt the circuit in response to a predetermined electrical condition of the circuit, means for automatically reclosing said contacts in response to a circuit interrupting operation, fluid dashpot means utilizing said arc extinguishing fluid for controlling operation of said contacts, said dashpot means having a pair of separate vent means located beneath the level of said fluid, a normally open valve or one of said vent means, means for counting the number of Operations of said brealer which occur in close succession, means operated by said counting means for closing said normally open valve after a predetermined number of operations of the breaker in close succession, a thermally responsve valve member for the other vent means to vary the flow of fluid therethrough in accordance with the temperature oi said fluid, and said thermally responsive valve member comprising check valve means movable into engagement with said vent opening by fluid displaced by said dashpot means during a cirouit opening operation and movable away from said vent opening by fluid attempting to enter said dashpot means during a circuit closing operation, and said valve means being movable in a different direction in response to the temperature of said fluid to vary the extent it covers the vent opening during a circuit opening operation.

References cited in the file Of thi patent UNITED STATES PATENTS Number Name Date 1,058,290 Corey Apr. 8, 1913 1,748A97 Scott et al Feb. 25, 1930 2,308,660 Kouyoumjian Jan. 19, 1943 2333504 Wallace Nov. 2, 1943 2,35'7,959 Kouyoumjian Sept. 12, 1944 2,528,197 Wallace Oct. 31, 1950

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