US2785347A - Time delay trip circuit breaker - Google Patents

Description

March l2, 1957 B G, TREMBLAY ETAL 2,785,347

TIME DELAY TRIP CIRCUIT BREAKER TIME] DELAY TRIP CIRCUIT BREAKER Filed July 3. 195.5

:5 sheds-sheet 2 WITNESS INVENTORS @www and william H Stuellein.

March 12, 1957 s. G. TREMBLAY ETAL 2,785,347

TIME DELAY TRIP CIRCUIT BREAKER Filed July 5, 1955 3 Sheets-Sheet 3 /l l W 309 323 3l? 325 Fi .4. 267 g 269 w|TNEssEs: |Nvx-:NToRs f Bernard G.Trem`bloy {4W/afg' and william H. swenein.

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United States Patent O TIME DELAY TRIP CIRCUIT BREAKER Bernard G. Tremblay, Pittsburgh, and William H. Stuellein, East McKeesport, Pa., assignors to Westis Electric Corporation, East Pittsburgh, Pai, a corporation of Pennsylvania Application July 3, 1953, Serial No. 365,822

7 Claims. (Cl. 317-178) This invention relates to circuit breakers and more particularly to circuit breakers embodying electromagnetic tripping means for instantaneously tripping the circuit breaker in response to overload current above a predetermined value and after a time delay on lesser overload currents.

An object of the invention is to provide a circuit breaker embodying an improved time delay trip device having means for reducing the time required to trip the breaker and clear the fault in response to short circuit currents.

Another object of the invention is to provide a circuit reaker embodying a trip device including a time delay device of the fluid dashpot type in which the time delay in the operation of the trip device is controlled by varying the rate of admission of tluid to the dashpot.

Another object of the invention is to provide a circuit breaker having an electroresponsive trip device embodying a time delay device of the uid dashpot type in which time delay and instantaneous tripping is eiiected in the operation of the trip device by the operation of valve means to admit uid to the dashpot at different rates.

Still another object of the invention is to provide a circuit breaker having an electroresponsive trip device embodying a time delay device of the fluid dashpot type in which time delay in the operation of the trip device is controlled by an adjustable valve for admitting iluid 't to said dashpot which valve is movable in response to certain overload currents to increase the flow of duid to said dashpot and additional valve means operated by said adjustable valve to further increase the flow of fluid to said dashpot.

The invention both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of a preferred embodiment thereof, when read in conjunction with the accompanying drawings.

ln said drawings:

Figure l is a side elevational View, partly in section, of a circuit breaker embodying the principles of the invention.

Fig. 2 is an enlarged sectional view through the trip device taken substantially along line ll-ll ol Fig. 3 and showing the magnet structure and the time-delay device.

Fig. 3 is a front elevational view of thc time-delay device including the tripping armature with the intermediate housing, the magnet yoke and the coil removed.

Fig. 4 is a vertical sectional view through the valve for controlling the admission of air to the dashpot.

.Reterrin g to Fig. l of the drawings, the circuit breaker includes a plurality ot pole units each comprising a contact structure indicated generally at 11 and an overcurrent trip device indicated generally at 13. The contact structure and the trip device for each pole unit are mounted on a separate insulating base 1S which is rigidly secured to a metal supporting panel 17. Since the pole units are ali Le, only the center pole unit is illustrate-:l and described herein.

The Contact structure 11 comprises stationary main 2,785,347 Patented Mar. l2, 1957 and arcing contacts 19 and 21, both secured to the inner end of a terminal conducting bar 23, and cooperating movable main and arcing contacts 25 and 27. The movable contacts are rigidly secured to a contact-carrying member 29 pivotally mounted by means of a pivot pin 31 and a channel-shaped switch arm 33 which, in turn, is -tally supported by pivot means 3S and brackets .3"7 rigidly mounted on the base l5.

The movable contact-carrying member 29 is electrically connected by means of a liexible conductor to the energizing coil of the trip device 13. A spring 41 compressel between the member 29 below itsY pivot 31 and the insulating base 15 provides contact pressure in the closed position of the breaker and also biases the movable Contact structure in opening direction.

F4he movable contact structure is normally maintained in the closed contact position by means of an operating mechanism indicated generally at 43 supported in a U-shaped frame 45. The frame 4S is supported on a platform 47 which forms a cross member of a generally U-shaped main bracket comprising a pair of spaced side members 49 rigidly connected at their outer ends by the cross member or platform 47. The platform 47 extends substantially across the width ot the breaker and the side members #t9 and is suitably secured to the metal panel 17 on the outside of the tWo outer pole units of he breaker.

The operating mechanism includes a lever 51 mounted on a pivot 53 supported in the side members of the trame d5. The lever 51 carries a rod SS extending across all of the poles of the breaker and is connected by means of insulating connecting members YS7 to the pivot pins in the free ends of the switch arms 33 for the several poles in the breaker so that upon operation of the rod the movable contacts of all the poles move in unison.

An operating linkage comprising toggle links 59, 61 and 63 is provided to normally hold the lever 51 and consequently the movable contacts in the closed position and to operate the movable contacts to open and closed positions. The toggle link S9 is pivotally connected to the lever 5l by a pivot 65 and the toggle link 63 is pivoted on a fixed pivot 67 supported on the frame 45. The toggle link 6l is pivotally connected to the links d and 63 respectively by knee pivots 69 and 71. i

The linkage S9, 61, 63 comprises two toggles, one of which S?, 61 may be designated as the tripping toggle and the other 6l, 93 as the closing toggle. The triping toggle 59, 61 is normally slightly underset above a line through the centers of the pivots 65, Gil, and the closing toggle 6l, is normally underset below a line through the pivots 67, 69. rthe closing toggle is normally prevented from collapsing downward by a support member i3 pivoted on a pin .75 supported in the frame d5 and having a shouldered portion engaging under the knee pivot '7l of the closing toggle.

The tripping toggle 59, 61 is normally biased in a direction to cause its collapse by a component of the torce of the springs 41 which bias the movable contact structures for the three poles of the breaker in opening direction and bias the three connecting members 57 toward the left (Fig. l). rl`he tripping toggle is normally prevented from collapsing by a main latch member 77 pivoted on the pin 53 and connected by a link 79 to the knee pivot 69 of the tripping toggle.

The main latch member is held in latching position by an intermediate latch lever Si pivoted on the pin 75. The intermediate latch lever 31 at its upper end carries a latch roller 53 engaging the main latch 77 and at its lower end has a latching portion 8S engaging a latch member 87 on a channel-shaped latch 89 pivoted on a pin 91 in the frame 45. A spring 93 serves to bias the .cam member 101 mounted on the inner end of a handle shaft 103 journalled in a bearing 105 mounted in the front piece of the frame 45. The handle is not shown in the drawings but is rigidly secured to the outer end of the shaft 103 and biased in both directions to a central position in a well known manner by a spring 167.

Rotation of the handle shaft 103 in tripping direction causes the cam member 101 to engage and actuate the latch member 89 in unlatching direction to unlatch the intermediate latch lever 81, which, in turn, releases the main latch 77. This permits the tripping toggle 59, 61 to collapse upwardly to effect opening of the breaker contacts. During the collapse of the tripping toggle, a portion 169 of the toggle link 61 engages and actuates the support member 73 to a non-supporting position, thereby freeing the closing toggle 61, 63. The closing toggle thereupon collapses downwardly and during its collapse resets and relatches the tripping toggle 59, 61.

The breaker contacts may now be operated to the closed position by rotating the shaft 103 and the cam 191 in the direction opposite to the tripping direction. This causes the cam 101 to engage a projection 111 on the closing toggle link 63 and moves this link counterclockwise about its pivot 67. This action straightens the closing toggle until the support member 73 resumes its supporting position below the knee pivot pin 71 of the closing toggle 61, 63. During the closing operation, the link 79 and latch 77 prevents collapse of the tripping toggle 59, 61 which acts as a thrust transmitting means and moves the movable contact structure to the closed position.

The breaker is automatically tripped open by operation of the trip device 13 for any pole of the breaker. The trip device 13 is of the dead front type, that is, the energizing coil is insulated from all other parts of the trip device. This permits adjustments to be made to the trip device with safety and without opening the breaker or deenergizing the power circuit.

The trip device is of the type disclosed in application Serial No. 317,952, led October 3l, 1952, now Patent No. 2,691,709, by Harry I. Lingal and Jerome Sandin and assigned to the assignee of this application.

The housing for the trip device comprises three separate parts each of molded insulating material. The upper part 113 of the housing supports the magnet yoke 115 (Fig. 2) and a trip rod 117 and insulates the magnet yoke from the energizing coil 119 (Figs. l and 2). The upper housing 113 is secured to the base 15 (Fig. l) by means of a bolt 121 which passes through aligned openings in the base 15, the lower end of the iiexible conductor 39, one end 123 of the energizing coil 119 and threadedly engages a metal insert 125 (Fig. 2) molded into the housing 113. The other end 127 of the energizing coil 119 is secured by means of a bolt 129 to the base and to the inner end of a terminal conductor 131.

A center housing portion 133 (Figs. l and 2) of molded insulating material is secured by means of screws 135 (only one being shown) to the upper housing 113 and is rigidly secured to the base 15 by means of a bolt 137 which extends through an opening in the base 15 and threadedly engages a metal insert 139 (Fig. 2) molded in the housing 133.

Supported in the upper housing 113 is the U-shaped laminated magnet yoke 115 having its legs 143 and 1415 extending downwardly through openings in the upper housing 113 and corresponding openings in the center housing portion 133. The top portion (Fig. 2) of the magnet yoke rests in a channel formed by side portions of the upper housing 113.

Mounted on the bottom of the center housing 133 and secured thereto by means of screws 163 (Fig. l) is a base or support 165 of molded insulating material on which is mounted the other parts of the trip device and the time delay device. Secured to the base 165 by means of screws 1169 (Fig. 2) is a diaphragm clamp and armature support member 171 of molded insulating material. Space/ members 173 molded integral with the member 171 extend upwardly therefrom and are joined by an integral cross member 175 (Fig. 2).

All of the parts mounted on the base 165 are assembled thereon before the member is mounted on the center housing member 133 (Figs. l and 2). These parts include a main armature 177 for cooperating with the magnet yoke 115 (Fig. 2). The main armature 177 is of laminated construction and has a bearing sleeve 17S mounted therein and a pin 179 extends therethrough (Fig. 5). The ends of the pin 179 are disposed in recesses 181 (Fig. 3) formed in the upper ends of the spaced members 173. When assembled in the lower support member the armature 177 is biased upwardly, biasing the ends of the pin 179 into the recesses 131 and retained in the position shown by a spring 133 (Fig. 2) compressed between the cross member 175 and the bottom surface of the armature. The spring 1&3 engages a spring guide on the cross member 175 and a spring guide 187 on the armature.

The outer laminations 136 of the magnet yoke 115 extend downwardly from the lower end of the leg 145 of the yoke and are provided with recesses 133 therein. After the magnet yoke 115 is inserted into the upper housing member 133 with an energizing coil 119 between the upper and center housing members, the base 165 with all of the parts mounted thereon is inserted upwardly into the center housing portion 133 and is secured thereto by the screws 163 (Fig. l).

As the bottom assemblage oi parts is placed in position in the center housing 133, bushings 199 (Figs. 2 and 3) mounted on the bearing 178 and disposed one on each side ot' the armature 177 engage the recesses 133 in the outer laminations 136 of the magnet yoke 115. The base 165 is moved into the center housing member 133 slightly beyond the point where the bushings 19h engage the recesses 183. This causes the ends of the pin 179 to separate slightly from the upper walls of the rccesses 131 in the members 173, slightly compressing the spring 183 and accurately locates the armature 177 relative to the magnet yoke 115 and the armature, when actuated, will cause the bearing sleeve 178 to pivot in the bushings 190.

As seen in Fig. 2 when the lower assemblage of parts is placed in position and the bushings 19t) are seated in the recesses 183, an arcuate surface 192 on the armature 177 adjacent the pivoted end thereof cooperates with an arcuate surface 194 on the lower end of the leg 145 of the magnet yoke to provide a constant predetermined air gap between the pivoted end of the armature and the magnet yoke in all positions of the armature.

The armature 177 is actuated to etect tripping of the breaker under the control of a time delay device 139 (Fig. 2) which comprises generally a tiexible diaphragm 191 anda valve device 193 (Fig. 4) for admitting air to the space below the diaphragm at various rates. The iiexible diaphragm 191 is disposed in -a chamber 195 formed in the base 165. The outer edge of the diaphragm 191 is clamped between the rim of the member 171 and the base 165 with a sealing gasket disposed between the diaphragm and the base 165. The central portion of the diaphragm 191 is clamped between upper and lower clamp members 197 `and 199, respectively, the lower clamp member 199 having a central threaded stud 2611 extending upwardly through an opening in the upper aes-5,347

clamp member. A nut 203 is threaded onto the stud 201 and securely clamps the parts together. The armature 177 is connected to the diaphragm by means of a linkage indicated generally at 205 (Fig. 2) which comprises a pair of spaced links 207 (only one being shown) disposed one on each side of an ear 209 on the armature 17 7 and pivotally connected thereto by means of a pin 211. A single link 213 disposed between the links 207 is pivotally connected by means of a pin 215 to the bifurcated upper end of the stud 201. rl`he link 213 carries a pin 217 which extends laterally on both sides thereof through slots 219 (only one being shown) in the links 207. The links 207 at their ends adjacent the diaphragm are provided with retaining lugs 221 and a coil spring 223 surrounding the linkage is compressed between spring retainers 225 supported on the pin 217 and the lugs 221 with a predetermined initial compression. Guide links 227 (Fig. 2) have one end pivoted on a fixed .pivot pin 229 supported in spaced bosses 231 formed on the base of the member 171 and are pivotally connected at their other ends to the pin 215 which connects the linkage 205 to the stud 201 to guide the movement of the diaphragm.

A U-shaped follower lever 233 (Figs. 2 and 3) comprising spaced levers 235 joined at one end by an integral yoke portion 237 straddles the armature 17'7 and is pivotally supported on opposite sides of the armature on the pin 179. Each of the levers 235 has a depending portion 239 formed inwardly toward each other below the armature 177 (Fig. 3) and the lower ends of the portions 239 rest on the pin 217 (see also Fig. 2), so that upward movement of the pin 217 causes clockwise movement of the follow lever 233 about the pin 179 to eiect tripping operation of the trip rod 117.

The trip rod 117 is rigidly mounted on the yoke portion 241 of an inverted U-shaped member 243, the legs 245 of which straddle the leg 143 of the magnet yoke 115. The member 243 is disposed for vertical movement and is guided by pins 247 projecting from opposite .sides of the leg 143 of the magnet yoke engaging elongated slots 249 in the legs 245 of the U-shaped members 243. Ears 251 formed outwardly from the lower ends of the legs 245 are disposed in the path of upward movement of the follow levers 235 (see Fig. 3) so that actuation of the follow levers 235 causes the free ends of the levers 235 to engage the ears 251 and move the member 243 and the trip rod 117 upwardly to cause a thimble 262 thereon to engage and actuate the strip bar 95 (Fig. 1) and trip the breaker.

The rate of tripping movement of the armature 177 and the follow lever 233 is controlled by the movement of the diaphragm 191 which, in turn, is controlled by the rate or" admission of air to the chamber 195 (Fig. 2) below the diaphragm. Air is admitted to the chamber 195 upon upward movement of the diaphragm by means of the valve device indicated generally at 193 (Figs. 1, 3 and 4). As best shown in Fig. 4, the valve device 193 comprises a tapered valve element 253 slidably disposed in the tapered bore 255 of a metallic valve insert 257 mounted in an opening in the base member 165. The valve element 253 is biased upwardly to a predetermined adjustable position by means of a. coil spring 259 compressed between the bottom of the valve element 253 and a valve cap 261 threaded onto a projection of the base 165.

A valve operating rod 263 attached to the valve element 263 extends upwardly from the valve element through a plurality of openings 265 in the top portion of the valve insert 257 and has a rounded upper end which bears against a concave portion 267 of a channel-shaped lever 269 (Figs. 2, 3 and 4). As seen in Figs. 2 and 3 the lever 269 is pivotally supported on a portion 271 of the support member 171 by means of a pin 273. The lever 269 is adjustable to vary the position of the valve element, as will be hereinafter described, to thereby vary the amount of time delay provided by the devices. When the armature 177 (Fig. 2), acting through the linkage 205, moves the diaphragm upwardly, air will be admitted at a rate determined by the adjusted position of the valve element to the chamber 19S through the openings 265 (Fig. 4), past the valve element 253 and through a passage 275 communicating the space below the valve element 253 with the chamber 195 below the diaphragm 191.

The amount of time delay provided in the operation of the trip device is determined by the rate of ow of air past the valve element 253. The rate of ow of air to the chamber 195 is varied by varying the position of the valve element 253 which varies the size of the opening between the valve element 253 and the bore 255 through which opening the air is required to ow. The position of the valve element 253 is varied by adjusting the channel-shaped lever 269. As shown in Fig. 3, the left-hand end of the lever 269 has a rounded portion 277 which is biased by the valve spring 259 (Fig. 4) into engagement with an angular portion 279 of a bracket 281. The portion 279 of the bracket threadedly engages a screw 283 rotatably mounted in the base of the lower housing 165. The screw 283 has a knob 285 secured to its lower end below the housing member and is retained in place by a spring washer 286 engaged in a groove in the screw just above the base 165.

By rotating the knob 285 and consequently the screw 283 the bracket 281 is moved up or down on the screw depending on the direction of rotation of the knob. This rotates the lever 269 which, through the engagement of the concave portion 267 (Fig. 4) thereon with the valve rod 263, positions the valve rod and the valve 253 accordingly.

The valve element 253 is also operated to full open position to provide instantaneous tripping in response to short circuit currents. The valve element 253 is operated to full open position by a secondary armature 287 (Figs. 2 and 3). The armature 287 is generally U-shaped and the two legs 239 thereof are pivotally supported in grooves 291 in the upper ends of the adjusting screw 283 and the upper end of a stud 293 (Fig. 3) rigidly mounted in the base 165. As best seen in Fig. 2, the armature 287 adjacent its right-hand end is provided with a clearance opening 295 for the spring 183 and the spring guide 185, the armature 287 in its retracted position resting on the cross member of the armature support 173. The armature 287 is connected to the lever 269 at the left of the pivot pin 273 (Fig. 3) by means of a link 297 so that upon operation of the armature 287 in a counterclockwise direction (Fig. 2) the lever 269 will be rotated clockwise to move the valve element 253 (Fig. 4) to its open position. When the valve 253 (Fig. 4) is thus moved downwardly it increases the opening between the valve and the bore of the valve insert 257 thus increasing the flow of air to the chamber so that the trip device functions substantially instantaneously to trip the breaker.

The main armature 177 is biased to its unattracted position by means of a spring 299 (Figs. 2 and 3) having one end connected to a projection 301 on the end of the armature and the other end connected to an adjustable member 303. The member 303 threadedly engages a screw 305 mounted for rotation in the base 165 and having an insulating knob 307 secured to the lower end thereof below the base, the screw 305 being held in place by a spring washer 309 engaging a groove in the screw just above the base. By rotating the screw 305 the member 303 travels up or down the screw depending upon the direction of rotation of the screw, thus varying the tension of the spring which varies the magnitude of overload current required to pick-up the armature 177.

The pick-up point for the secondary or instantaneous armature 287 may be similarly adjusted. The armature 287 is biased to its unattracted position (Fig. 3) by means ofaspring 313 (Fig. 3) having `oneend connected to the armature andthe other end connected to an adjustable member315threadedlyengaging a screw 317 rotatablyy mountedin the'b'ase 165; The screw 317 has-a knob 319 secured to the lower end thereof and is held in place by a spring washer"(not shown) engaging a groove in the screw317 just above the base 165. Rotation of the screw 317 vby the knob-3119 moves'the member 315 up and down according to the direction the screw is turned to vary the tension of theispring`313'which varies the pick-up pointof the armature 287.

The adjustable members Z, 303, and 3315 respectivelyl areI provided with Y indicating' means comprising projections 1321; 323'and- 325 (Fig. 3) which engage vertical slots 4327 (Fig.Y 2)`-inv an vindex plate 329"supported between theAcenter housing'133 andthe lower housing 165i Means is provided to exhaust the air from the chamber 195-`below the Vdiaphragm'lii following a tripping operation to'permit resetting of the parts to their normal positions. This-'means comprises afreset valve device disposedin a recess inthe bottom of the valve cap 261 (Fig. 4). The reset vaive device comprises a valve Velement 331 of thin resilient material supported on a. metal washer 333 having its periphery serratedas shown at 335 (Fig. 4). The washer 333 is biased against a shoulder in the valve cap 261 by a light spring 337 compressed between'the washer 333 and a retaining disc'339. The retainingdis'c 339 is rmly held in place Vby forming over the thin lower end of the valve capr261 against the bottom of the disc.339 as shown at 341 (Fig. 4). During a tripping operation, `air attempting to ow through the serrations 335moves the valve element 331 up against the central portion of the valve cap thus sealing oi'r the cen-V trai opening Atherethrough and forcing the air admitted to the chamber 195m' pass thel valve 253 which controls the amount of time delay in the operation of the tripdevice.

After the circuit breaker has been tripped open, or if a fault'has occurred and cleared before the breaker is tripped, the parts of the tripV device are reset by the weight of Vthe armature A77 and the force of the springr 279 -(Fig. 2) applied to the diaphragm 191. This forces the air from the chamber 195 out through the passage 275 (Fig 4), through the central opening in the valve cap 261, around the reset valve element 331, through the serrations on the washer 333 and through the opening in the retainer disc 339 to atmosphere. The resetting actionr does not unseat the washer 333 since there is amplespacefor the air to ow around the valve element 331'and through the serrations 335 in the washer to provide'for quickresetting of the parts.

Means is provided for admitting additional air tothe chamber 195 to'permit high-speed operation of the trip device and opening Yor" the breaker in response to certain shortcircuit currents. This means comprisesV the reset' valve 331 (Fig. 4) and an extension M3 on the valve element.v 253. When the secondary armature 2E? (Figs. 2 and3) '.is actuated in response to such a short'circuit current it operates the let/e122@ to move the valve element 253 .to its'openposition. lnits open position the valve element253 still.' so- .ewhat restrictsthe fiowof air to the chamberr195. Hor/ever, when: the valve element 253 moves to its open position the extension 3431thereon en-v gages-thereset-valve element`331 and moves this element.

' together `'with the washer 333 downward to greatly innur the reset valve element 333i to'their nor lpositions The invention provides Vmeansresponsive to excessive fault currents for increasing the'admissionof iiuid to a finiti dashpot timeV delay device for a-circuit'breaker whereby' the time required -to instantaneouslytrip thebreaker open and clear-the fault is greatiy reduced.V

While thelvform of mechanism shown and'desc-ribed' herein is admirably adapted to fulfill the objects primarily stated, it to be understoodfthat it is not intended to confinethe invention to the form of embodiment disclosed herein, for it is susceptible et embodimentin various forms without departing from the spirit of the invention.

v'e claim as our invention:

i. in anelectroresponsive trip' device for a circuit breaker having a timedelay device comprising a uid position for admitting iiuidat a predetermined rate to said dashpot, adjusting means for ad'iusting'the i i l position of said valve means `to vary the rate or admission of tluidrfto said dashpot, means responsive to overcurrents for Vmoving said valve means to another position to increase the rate of v'admission of fluid to said dashpot, and additional valve means Voperative by lmovement of said iirst mentioned vaive means to said other position.

to furthery increase the rate of admission of fluid to said dashpot.

2. In an electroresponsive trip device for a circuit open position for admittingV duid at a predetermined ratevto said dashpot to effect a time delay in the operation of said trip device, reset valve means for venting to said dashpot to effect atime delay in the operation of said trip device, reset valve means having a normal open position for venting said chamber to permit resetting o said trip device,.means responsive to overioad currents ofcertain value for moving said valve means to another position to increase the rate of admission of Huid to said chamber, and means operative.

by movement of said valve means to said other position for moving said `resetvalve to another open position to further increase the rate ofadmission of fluid to said chamber.

4. inv an electroresponsive trip device for a circuit breakery having` a time deiay device comprising a fluid dashpot, means definingy a chamber in said dashpot, a valve having an initiai open position for admitting duid to said chamber at apredetermined rate to eti-ect a time delay in the operation of said trip device in response to certain overload conditions, venting means for venting saidchamb'er to permit resetting said trip device, a normally open reset valve for controlling said venting means, means responsive to certain other overload conditions for movingrsaid valve means to another position to increase the now of fluid to said chamber, and means' operable Vby movement of said valve means to said other position'torrengagingvandmoving 'said reset valveA to a further open position to further increase the tlow of liuid to said chamber.

5. In an electroresponsive trip device for a circuit breaker having a time-delay device comprising a iiuid dashpot, valve means having an initial open position for admitting fluid to said dashpot at a predetermined rate to eitect a time delay in the operation of said trip device, means deiining a vent for venting fluid from said dashpot to permit resetting of said trip device, a reset valve having a normally open position for controlling said vent, said reset valve being movable in one direction to close said vent upon operation of said trip device in response to certain abnormal circuit conditions, means responsive to certain other abnormal circuit conditions for moving said valve means to another position to increase the flew of duid to said dashpot, and means operable by said valve means when valve means is operated to said other position for engaging in moving said reset valve in another direction to further increase the iiow of fluid to said dashpot.

6. In an electroresponsive trip device for a circuit breaker having a time delay device comprising a uid dashpot, valve means having an initial open position for admitting uid to said dashpot at a predetermined rate to effect a time delay in the operation of said trip device in response to overload currents below a predetermined value, reset valve means for venting said dashpot to permit resetting of said trip device, means comprising an armature operative in response to overload currents above said predetermined value for moving said Valve means 10 from said initial position to another position to increase the rate of ow of uid to said dashpot, and means on said valve means operative upon movement of said valve means to said other position for engaging and moving said reset valve means to further increase the rate of ow of fluid to said dashpot.

7. In an electroresponsive trip device for a circuit breaker having a time delay device comprising a uid dashpot, valve means having an initial open position for admitting tiuid to said dashpot at a predetermined rate to effect a time delay in the operation of said trip device in response to overload currents below a predetermined value, adjusting means for adjusting the initial open position of said valve means to vary the amount of time delay in the operation ol said trip device, reset valve means for venting said dashpot to permit resetting of said trip device, means comprising an armature operative in response to overload currents above said predetermined value for moving said valve means from said initial position to another position to increase the rate of ow of iiuid to said dashpot, and means on said valve means operative upon movement of said valve means to said other position for engaging and moving said reset Valve means to further increase the rate of flow of iiuid to said dashpot.

References Cited in the file of this patent UNiTED STATES PATENTS

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