US2644114A - Line-sectionalizer integrator - Google Patents

Description

June 1953 A. w. EDWARDS ETAL 2,644

I LINE-SECTIONALIZER INTEGRATOR Filed'July 21, 1950 2 Sheets-Sheet 2 Fig.2.

WITNESSES: INVENTORS Andrew W. Edwards 8 games M. Wallace.

6. 7c. g I ATTORNEY Patented June 30, 1953 LINE-'SECTIONALIZER INTEGRATOR Andrew W. Edwards and James M. Wallace, East McKeesport, Pa., assignors to Westinghouse Electric CorporatiomEast Pittsburgh, Pa., a corporation of Pennsylvania Application July 21, 1950, Serial N 0. 175,276

27 Glaims. (Cl. SPY-22) Our invention relates to novel time-delayed resetting-means for automatically resetting the integrators or counting-mechanisms of line-sectionalizers. With slight'modifications, however, the invention could be used in the countingmechanisms of reclosers or other devices.

Line-sectionalizers and reclosers are used on rural alternating-current distribution-lines, The recloser is used between the distribution -lineand the electric power-source. This recloser responds to predetermined overcurrent-conditions, indicative of a fault, and quickly opens its line-contact, after which it quickly recloses said contact, and if the faulthas not automatically cleared itself during the period of deenergization of the line, the recloser quickly again opens its linecontact, and keeps up this process for a predetermined number of rapidly repeating cycles, usually four, and if the fault still persists this time, the recloser opens up its line-contact and looks it open, thereby permanently deenergizing the line until the line can be repaired. The :lunction or the line-sectionalizer is to break up the line into tionaliz-er, which counts a. predetermined rapid succession of overcurrent-conditions, for a number of times which is less than the recloser-times,

and then opens itssectionalizer contact during a no-current period of the recloser. In this way, a faulted section is removed by the sectional'izer, before the recloser permanently trips out the entire distribution-system.

In the case of both the rec'loser and the sectionalizer, it is necessary for the integrator or automatic counting-mechanism to be self-resetting. Ordinarily, this resetting is accomplished by slowly biasing a forwardly-ratcheted countermember so that it will slowly return to its original unadvanced position whenever it is displaced at all. I'his requires some sort of time-delay device for resetting the counter-mechanism. Oil-dashpots for this purpose present problems of oilleahage, evaporation, etc. Mechanical timers are usually too expensive for these applications. Airdashpots' for resetting the counter-member have the disadvantage of an inherently short travel and considerable backlash, so that it is dii'ficult to use such airdashpots directly on the forwardly ratcheted. counter-member, so as to allow said counter-member to integrate its travel, and still allow resetting.

Our present invention is an improvement over an invention of Andrew W. Edwards and Earl F. Beach, Serial No. 175,273, filed concurrently herewith, relating to the broad idea of providing a holding-detent for the advanced positions of the counterrod, and releasing this holding-detent by means of any suitable form of light-weight timedelay means, such as an air-dashpot.

Our present invention relates to the provision of an electro-thermal time-delay means, such as a current-traversed bimetallic element, or other current-responsive time-delay means, for controlling the release of the holding-detent. Such a bimetallic member may be released either during its cooling cycle or during its heating cycle. Que feature of our invention provides a means which is responsive to the current traversing the magnetizing coil, for energizing the time-delay device with a currcnt'having a limited magnitude.

With the foregoing and other objects in view, our invention consists in the systems, combinations, apparatus, parts, and methods of design and operation, hereinafter described and claimed, and illustrated in the accompanying drawings,

wherein Figures 1 and 2 are somewhat diagrammatic elevational views, partly in section, showing two illustrative forms of embodiment of our invention.

The drawings are intended more to illustrate the principle of the invention, rather than its precise structure. While the invention is shown in the drawings, and will be described, as being embodied in a line-sectionalizer, it is to be understood that the counting-mechanism part of the illustrated structure, to which our invention particularly relates, may be used also in reclosers and perhaps also in other devices, with suitable modifications.

The illustrated. line-sectionalizer is shown in Fig. 1 as being mounted in a cylindrical porcelain insulator l, which normally stands in an essentially vertical position. One of the line-terminals, Li, is connected tothe top-plate 2 of the sectionalizer, while the other line-terminal, L2, is connected to the bottom plate .3 of the sectiona'lizer. The sectionalizer is supported by a centrally located mounting-bracket 4, which is usually secured somewhere up on a pole (not shown). 4

:On the underside of the top-plate .2 is shown the spring-pressed stationary contact-member 5 of the sectionalizer-contact or disconnect-switch, which is connected in series with the distributionline. The movable contact-member of this combination is shown in the form of a vertically movable contact-rod t, which normally presses up into contact with the stationary contact 5. The contact-rod 6 is normally biased downwardly, in a contact-opening direction, not only by its own weight, but also by a tension-spring l. The bottom end of the contact-rod extends down below the bottom plate and is provided with a looped operating-terminal or hookeye 8 which can be engaged by a switch-stick (not shown) for manually reclosing the sectionalizer-contact.

An intermediate portion of the vertically movable contact-rod 6 is provided with a shoulder IO which is engaged by the latch-pin I I of a pivotally supported latch-member I2, which is pro-- vided with a horizontally extending arm I 3 which has to be pushed up in order to release the latch pin II from its normal position under the rodshoulder ID.

The vertically movable contact-rod 6 is also provided with a flexible current-carrying cable M which is secured to one end of a magnetizing coil I5, the other terminal of which is connected to the base-plate 3, as indicated at I6.

The magnetizing coil I is a part of an electromagnet device which has upper and lower pole-piece plates 2! and 22, and also a vertically movable armature 23 which moves vertically inside of the coil I5. In the form of embodiment of our invention which is shown in Fig. 1, the armature 23 is biased upwardly, into its normal unattracted position, by means of a compressionspring 24. The armature 23 moves up and down between a predetermined retracted upper position, as shown, and an advanced lower position when the bottom of the armature 23 is attracted magnetically down to, or nearly to, the lower pole-face plate 22 of the electromagnet-struc ture.

Slidably mounted at one side of the magnetizing coil I5, is a vertically movable counter-bar 3B, which is normally biased, as by gravity, to its lowermost position, and which is upwardly advanceable, in discrete steps, until its top end 3I pushes up on the latch-arm l3 and unlatches the vertically movable contact-rod or trip-rod E. The lower end of the counter-bar extends below the sectionalizer-bottom 3, and is provided with a looped operating-terminal or hookeye 32, which may be engaged by a switch-stick (not shown) for manually pushing up on the counterrod 30 and tripping out the sectionalizer. The upper portion of the counter-rod 30 is provided with a series of vertically spaced notches or shoulders 33, which are used in the step-by-step vertical advancement of the counter-rod, and also in temporarily holding the counter-rod in advanced position, as will be subsequently described.

The top of the armature 23 in Fig. 1 carries a horizontal arm which is pivotally attached to a counter-advancing pawl or ratchet 38, which cooperates with the notched counter-rod 30. Each time the armature 23 returns upwardly to its unattracted position after having been pulled downwardly by a sufficiently strong over-currentenergization of the magnetizing coil I5, the horiaontal arm 35 rises and tilts the counter-pawl 26 into its operative position, as shown in Fig. 1, so that this pawl engages one of the lifting-notches or shoulders 33 on the counter-rod 30, and then lifts this shoulder through a predetermined distance, thus constituting the first movement in the step-by-step vertical advance-movement of the counter-rod 30.

The top end of the counter-rod 30 is held in any one of a plurality of advanced positions by means of a holding-detent or pawl 31, which is vertically spaced above the counter-pawl 36. In the form of our invention which is shown in Fig.

1, the holding-detent 31 is normally in an inoperative position, in which it does not engage under any of the notches or shoulders 33 on the counter-rod 30. This holding-detent 31 is actuated by means of an electro-thermal time-delay device, which is illustrated in the form of a bimetallic element 38 which is mounted on a suitable support 38'.

The bimetallic element 38 is supplied with a current-supply circuit 39 which preferably supplies a current which is approximately proportional to the line-current, or to the current through the magnetizing coil I5, but which is preferably limited as to its permissible overcurrent magnitudes. A convenient means to this end is associated with the electromagnet-struc ture, in which we have provided a small-crosssection core-portion or magnetizable-rod 4U. whichis disposed between the upper and lower pole-face plates 2I and 22, outside of the coil I5. This small-sectioned rod or core 40 in Fig. 1 saturates under overcurrent-conditions, which are in excess of the minimum overcurrent-condition necessary to actuate the magnetizing coil I5. This saturable core 40 is also magnetically shunted by means of a magnetic circuit-member 4| having an air gap 4| therein, so that, when the rod 40 saturates, the heavy magnetic flux is forced to travel across the air gap 4|. The saturable rod 40 is provided with a suitable secondary transformer-winding 42, which energizes the supply-circuit 39 for the bimetallic member 38.

The operation of the sectionalizer shown in Fig. 1 is as follows. Upon the occurrence of a sufficient overload, the magnetizing coil I5 draws the armature 23 downward and compresses its spring 2d. The increased alternating flux in the electromagnet, due to this overcur1'ent-condition, increases the output-current of the secondary coil 42 to the point where it quickly overheats the bimetal member 38 and causes it to be deflected into the dotted-line position shown in Fig. 1, wherein it moves the holding--detent 3'! into an operative position in which it is in readiness to hold the counter-rod 30 in advanced positions when it is advanced in the counting-direction. The downward attraction of the armature 23 moves the counter-advancing pawl 36 downwardly, in readiness to ratchet the counter-bar 30 one step upwardly on the return-stroke of the armature.

When the line-current is interrupted by the associated recloser (not shown), or from any other cause, the armature 23 of Fig. l immediately returns upwardly to its original position, under the bias of its spring 24, and the counteradvancing pawl 36 advances the counter-rod 3i! upwardl by a little more than the distance between successive notches or shoulders 33. During this upward advance of the COUIllIET-QOd 30, the holding-=detent 3"! is deflected. sufliciently by the contourof shoulder 33 so as to move under one of the notches or shoulders 33, in readi ness to hold the counter rod in the first step of its advanced position.

If a predetermined number (say three) of such operations occur in rapid succession, the counterrod 30 will be advanced upwardly, step by step, until the latch-arm I3 is tripped, and the disconnect rod 3 is released, to move downwardly and interrupt the circuit at 5.

The bimetallic element 38 has such a thermal capacity, or snap-action, or both, that it will not cool off sufliciently to inactivate the holding-detent 31 during brief no-current periods of the recloser (not shown) but if the linecurrent should permanently become zero, or even if the line-current should assume normal values, the bimetallic element 31 will gradually cool and return to its normal position, illustrated in full lines in Fig. 1, thus disengaging the holding detent 31 from the counter-rod 30, and permitting the counter-rod to immediately reset by gravity.

Since the line-sectionalizer must operate over a wide range of overcurrents, some of which may be several times the magnitude of the mini-- mum fault-current which will actuate the armature 23, it is usually desirable to limit the possible maximum value of the overcurrent which is applied to the bimetallic device 38, so as to avoid the danger of burning it out. This taken care of by using a small magnetic crosssection for the core as of the secondary coil 42, and putting a gap 4| in. parallel thereto. Thus, at some current-value which is slightly above the minimum operating current of the sectional izer, the limited-section core 40 will saturate,

over into its operative position in readiness to prevent the falling back of said counter-rod This adjustment of the holding-detent closes the heater-circuit 39 and causes the energization of the bimetallic element 38 for the brief moment during which an overcurrent-condition lasts. When the overcurrent is interrupte by the recloser or protective device (not shown), the armature 23' drops back, bringing with it the counter detent while the bimetallic element 3%" holds the holding-detent all in position, and the holding-detent holds the counterbar to up in its first advance-step. lhe brief impulse of overcurrent is far too small to heat the bimetallic element to its thermally respon sive temperature, particularly as the saturatin point of the saturable secondary core may now (in 2) be chosen to correspond to a normal current-value.

and any additional flux will be carried by the Fig. 2 illustrates a modification of our device in which the holding-detent 31' is released by the heating of the bimetallic element 38 on normal current-410w, rather than by cooling. In this case, the armature 23' is disposed so that it normally project's down below the lower end of the magnetizing-coil l5, and its biasing-spring it is disposed above it, to bias it downwardly. This armature ESQ-1h Fig. 2, is provided with an upwardly extending armature-rod 43, an in termediate portion of which carries the previously described arm for advancing the counter rod all.

The holding-detent 31', in Fig. 2, is shown as being horizontally displaceable in a guide-member 44, and as being normally withdrawn out of engagement with the counter-rod 39, by means of a spring 15. The rear end of the holdingdetent 3? is in engagement with a bellcrank which is rocked by the top of the armature-rod 53 when the latter moves up into its overcurrentposition, and this rocking of the bellcrank moves the holding-detent over into its operative position in which it can latch under one of the notches or shoulders 33 of the counter-rod This holding-detent 3'! is provided with a latchpin 4! which is adapted to be held over by a latch 48 on the bimetallic element 33" when the holding-detent 31' is in its operative position.

In Fig. 2, the terminals of the heater energia ing circuit 39 are connected respectively to the fixed end of the bimetallic element 38 and the holding-detent 3?. The energizing circuit 39 for the bimetallic element 38 is thus normally open, and is closed when the holding-detent 3' is pushed over to its operative position, wherein said circuit 239 is closed by the engagement of the latch. 48 of the bimetallic element behind the latch-pin l! of the holding-detent. There=- after said circuit 39' remains closed until the heating of the bimetallic element 38".causes it to deflect to its dotted-line heated. position, wherein it releases the latch-pin 41, permitting the holding-detent 31 to move back to its inoperative position under the pull of its spring to.

In the operation of the line sectionalizer of Fig. 2, the first occurrence of an overcurrentcondition advances the armature 23 upwardly, and thus advances the counter-rod 3G one notch upwardly, and also moves the -holding detent 3'! 11 the fault which caused the overcurrentcondition clears itself before the predetermined count for which the integrator or counter is set, in Fig. 2, the normal load-current oi the line will continue to energize the heater-circuit t9, hence the bimetallic elemen 33", for awhile; and after any suitable time-delay this bimetallic element 33 will heat up, release the holding detent 3?, and deen'ergize its energising circuit 3d at ll and The release of the holdingdetent lets the counter bar drop back immediately to its reset position.

If the fault persists, the sectionalizer of Fig. 2 will advance its counter-bar so for the predetermined number of steps, during recurrent overcurrent-ccnditions; and during the last overcurrent condition said counter-bar will trip-out the trip-lever i3, releasing the trip-pin H from its holding-engagement with the interrupter-bar 5. Since this tripping action, in Fig. 2, occurs during an over current -condition, it is now desirable, at least in sectionalizer applications of the integratormechanism, to prevent the immediate opening or downward movement of the interrupter-bar 6, until the recloser (not shown) has interrupted the line-current. To this end, we have shown a means for temporarily holding the interrupter bar in its upper (or closed) position, as described and claimed in the previously mentioned copending application of Andrew W. Edwards and Earl F. Beach.

Thus, as shown in Fig. 2 of our drawings, the horizontal arm 35, which is carried by the upstanding armature-rod is pivotally connected to a retainer-pawl Each time the armaturerod ifi moves upwardly to the overcurrent-position, the horizontal arm 35 rocks the retainerpawl 58 into position under a corresponding shoulder 55 on the interrupter-rod 6, and said horizontal arm 35 lifts this retainer-pawl up substantially to the underside of said shoulder 51. Thus, in the final integrator operation, when the rod-holding latch-pin H is unlatched, the interrupter-rod ii does not immediately fall, because this rod is temporarily held up by the retainerlatch H] as just described. This holding action I continues until the magnetizing coil [5 is deenergized, whereupon the interrupter-rod 3 moves downward under the bias of its spring 1, and the top end of this interrupter-rod is moved out of contact with the stationary line-contact 5, thus effecting the interrupter-action of the line-sew tionalizer.

The sectionalizer of Fig. 2 may be reset by reclosing the interrupter-rod 6 with a switch-stick (not shown), and holding it closed for the brief time which is required for the normal load-current in the line to heat up the bimetallic element or thermal time-delay device 38", whereupon the counter-rod 30 will be released and will reset itself by gravity, and the timer-circuit 39 will be opened by the disengagement of the holding-detent 31 from the latch 48 of the time-delay device. Then the integrator latch-pin ll will hold the interrupter-rod in its elevated or closed position, and the switch-stick can be disengaged from the interrupter-rod 6.

It will be observed that, in either of the il1ustrated forms of our invention, we have provided inexpensive, and yet reliable, current-responsive time-delay means for controlling the release of a holding-detent in an integrator.

While we have described but two illustrative forms of embodiment of our invention, we wish it to be understood that we are not limited to the precise illustrated structures or combinations, and we desire that the appended claims shall be accorded the broadest construction consistent with their language.

We claim as our invention:

1. An integrator-mechanism comprising: an electromagnet-device having a magnetizing coil and having an armature which is movable from a predetermined unattracted position to a predetermined attracted position to which it is attracted by the magnetic flux produced by a predetermined cvercnrrent in the coil; a movable counter-mermber which is biased toward an inoperative position; a one-way drive-mechanism for imparting one step of a step-by-step advance to said counter-member each time said armature moves in one direction of its aforesaid movement; a holding-detent for at times holding said counter member in advanced positions; and a currentresponsive thermal time-delay device operable independently of the armature for at times making said holding-detent inoperative.

2. The invention as defined in claim 1, in combination with means for energizing the timedelay device with current responsive to the current traversing said coil.

3. The invention as defined in claim 1, in combination with means responsive to the current traversing said coil for energizing the time-delay device with current having a limited magnitude.

i. An integrator-mechanism comprising: an electromagnet-device having a magnetizing coil and having an armature which is movable from a predetermined unattracted position to a predetermined attracted position to which it is attracted by the magnetic flux produced by a predetermined overcurrent in the coil; a movable counter-member which is biased toward an inoperative position; a one-way drive-mechanism for imparting one step of a step-by-step advance to said counter-member each time said armature moves in one direction of its aforesaid movement; a holding-detent for at times holding said counter-member in advanced positions, said holdingdetent being normally in an inoperative position; and a time-delay device, responsive to temporary overcurrent-values in said coil, for temporarily moving said holding-detent to an operative position independently of the armature.

5. The invention as defined in claim 4, char acterized by said current-responsive time-delay device being thermally responsive.

6. An integrator-mechanism comprising: an electromagnet device having a magnetizing coil and having an armature which is movable from a predetermined unattracted position to a predeiii) termined attracted position to which it is attracted by the magnetic flux produced by a predetermined overcurrent in the coil; a movable counter-member which is biased toward an inoperative position; a one-way drive-mechanism for imparting one step of a step-by-step advance to said counter-member each time said armature moves in one direction of its aforesaid movement; a holding-detent for at times holding said counter-member in advanced positions; a current-responsive time-delay device for at times making said holding-detent inoperative; means for closing an energizing-circuit for said time-delay device when said counter-member is first advanced; and means for interrupting said energizing-circuit when the time-delay device makes said holding-detent inoperative.

'7. The invention as defined in claim 6, characterized by said current-responsive time-delay device being thermally responsive.

8. An integrator-mechanism comprising: an electromagnet-device having a magnetizing coil and having an armature which is movable from a predetermined unattracted position to a predetermined attracted position to which it is attracted by the magnetic fiux produced by a predetermined overcurrent in the coil; a movable counter-member which is biased toward an inoperative position; a oneway drive-mechanism for imparting one step of a step-by-step advance to counter-member each time said armature moves in one direction of its aforesaid movement; a holding-detent for at times holding said counter-member in advanced positions; a current-responsive time-delay device for at times making said hclding-detent inoperative; and means for closing an energizing-circuit for said time-delay device when said armature first moves to its overcurrent position.

9. The invention as defined in claim 8, in coinbination with means for interrupting said energizing-circuit when the time-delay device makes said holding-detent inoperative.

10. The invention as defined in claim 8, characterized by said current-responsive time-delay device being thermally responsive.

3.1. An integrator-mechanism comprising: an electromagnet-device having a magnetizing coil and having an armature which is movable from a predetermined unattraoted position to a predetermined attracted position to which it is attracted by the magnetic flux produced by a predetermined overcurrent in the coil; a movable counter-member which is biased toward an inoperative position; a one-way drive-mechanism for imparting one step of a step-by-step advance to said counter-member each time said armature moves one direction of its aforesaid movement; a holding-detent for at times holding said counter-member in advanced positions, said holding detent being normally in an inoperative position; a current-responsive time delay device; a normaliy open timer-circuit adapted, when energized, to supply the time-delay device with a current which is responsive to the current traversing said coil; means for closing said timer-circuit and setting the holding-detent in its operative position when the counter-member is first advanced; and means for causing said tiine-delay device, at the end of its time-delay period, to open said timer-- circuit and set the holding-detent in its inoperative position.

12. The invention as defined in claim 11, characterized by said current-responsive time-delay device being thermally responsive.

13. An integrator-=mechanism comprising: an electromagnet-device having a magnetizing coil and having an armature which is movable from a predetermined unattracted position to a prede" termined attracted position to which it is at 5 tracted by the magnetic flux produced by a predetermined overcurrent in the coil; a movable counter-member which biased toward an inoperative position; a one-way drive mechanisin for imparting one step of a step-by-step advance 10 to said counter-member each time said armature moves to its unattracted position; a holding-detent for at times holding said countcrnnember in advanced positions, said holding-detent being normally in an inoperative position; and a time s delay device, responsive to temper rent-values in said coil, for temporariiy mom at, said holding detent to operative position independently of said armature.

14. The invention as defined in claim 13, char 3 acterized by said current-responsive tirnadelay device being thermally responsive.

15. The invention as defined in claim 13, combination with means responsive to the rent traversing said col for energ' a t e blink; delay device with current having Jed magnitude.

16. An integrator-mechanisin comp .ng: an electromagnet-device having magnet ing coil and having an armature which is movable from 3. a predetermined unattracted position to predetermined attracted position to which it is at tracted by the magnetic flux produced by a pre determined overcurrent in the coil; novable counter-member which. is biased towel i operative position, a one-way drive-meehan nri for imparting one step of a step-by-step advance to said counter-member each time said ature moves to its overcurrent position; a holdi. 2- detent for at times holding said counter=member 4;; in advanced positions; a current=responsive timedelay device for at times making said holdin detent inoperative; means for closing an en rgizing-oircuit for said time-delay device when said counter member is first advanced; and means for interrupting said energizing-circuit when the time-delay device makes said holding detent inoperative.

17. An integrator-mechanism comprising: an electromagnet-device having a magnetizing coil and having an armature which is movable from a predetermined unattracted position to a predetermined attracted position to which it is attracted by the magnetic flux produced by a predetermined overcurrent in the coil: movable counter-member which is biased toward an inoperative position; a one-way drive-mechanism for imparting one step of a step-by-step advance to said counter-member each time armature moves to its overcurrent position; a holding-de CO tent for at times holding said counter-1nember in advanced positions, said holding-detent being normally in an inoperative position; a currentresponsive time-delay device, a normally open timer-circuit adapted, when energized, to supply the time-delay device with a current which is responsive to the current traversing said coil: means for closing said timercircuit and. setting the holding-detent in its operative position when the counter-member is first advanced; and means 70 for causing said time-delay device, at the end of its time-delay period, to open said timer-circuit and set the holding detent in its inoperative position.

18. The invention as defined in claim 17, char- 75 10 acterized by said current-responsive time-delay device being thermally responsive.

19. The invention as defined in claim 17, in combination with: a response-member which is biased toward a responding position; a latch for normally holding said response-member from responding; means whereby the counter-member, at the termination of its predetermined step-bystep advance, releases said latch; and means whereby the armature, in its overcurrent position, interposes a temporary block against any substantial movement of the response-member in its responding direction,

20. An integrator-mechanism comprising: an electromagnet-device having a magnetizing coil and having an armature which is movable from a predetermined unattracted position to a predetermined attracted position to which it is attracted by the magnetic flux produced by a predetermined overcurrent in the coil; a movable counter-member which is biased toward an inoperative position; a one-way drive-mechanism for imparting one step of a step-by-step advance to said counter-member eachtime said armature moves to its overcurrent-position; a holdingdetent for at times holding said counter-memher in advanced positions, said holding-detent being normally in an inoperative position; a current-responsive time-delay device; a normally open timer-circuit adapted, when energized, to supply the time-delay device with a heating-current; means responsive to the current traversing said coil for providing a source of current of limited magnitude for said timercircuit; means for closing said timer-circuit and setting the holding-detent in its operative position when the counter-member is first advanced; and means for causing said time-delay device, at the end of its time-delay period, to open said timer-circuit and set the holdingdetent in its inoperative position.

, 21. The invention as defined in claim 20, in combination with: a response-member which is biased toward a responding position; a latch for normally holding said response-member from responding; means whereby the counter-member, at the termination of its predetermined step-by-step advance, releases said latch; and means whereby the armature, in its overcurrent position, interposes a temporary block against any substantial movement of the response-member in its responding direction.

22. Circuit interrupting apparatus comprising separable contacts, electroresponsive means operable in response to a predetermined value of current, a movable counter member, a one-way drive mechanism for imparting one step of a step-by-step advance to said counter member in response to operation of the electroresponsive means for eventually making it effective to re tain said contact means separated, and a thermally responsive time delay holding device for holding said counter member in an advanced position for a predetermined time, said time delay device having a thermal element responsive to the current of said electroresponsive means.

23. A circuit interrupter comprising, separable contacts, electroresponsive means operable in response to an overcurrent, a counter member operable to effect separation of said contacts, means operable in response to operation of said electroresponsive means for imparting one step of a step-by-step advance to said counter memher for effecting separation of said contacts upon a predetermined number of such steps, and a time delay detent actuated to retain said counter member in an advanced position including a thermal-responsive element disposed to be operated a predetermined time after cessation of the overcurrent in accordance with the current through said electroresponsive means to effect a delayed release of said counter member.

24. A circuit interrupter comprising, separable contacts, electroresponsive means operable in response to a current of a predetermined value, a counter having a member actuated by the electroresponsive means to advance in a step-bystep relation to effect retention of said contacts in a separated position, and means including a thermally responsive element having a releasable detent portion engaging the counter to hold it in an advanced position for a predetermined time.

25. A circuit interrupter comprising, separable contacts, electroresponsive means operable in response to an overload, means including a movable counter disposed to efiect retention of said contacts in a separated condition in response to a predetermined number of counting operations, a one-Way drive mechanism for imparting a one step advance of a step-by-step counting operation in response to each operation of the electroresponsive means, a holding detent for holding said counter member in an advanced position, and time delay means including a thermal responsive device responsive to the current in said electroresponsive means for rendering said detent inoperative a predetermined time after deenergization of said electroresponsive means.

26. In a circuit interrupter, separable contacts, electroresponsive means having an armature movable in response to an overcurrent, means biasing the armature to return to a normal position upon termination of the over-current, a counter member movable a predetermined distance to effect separation of said contacts, means imparting one step of a step-bystep movement to said counter member each time the armature returns to its normal position for eifecting advancement for said predetermined distance, and means including a thermal element responsive to current in said electroresponsive means, said thermal element having a detent portion for retaining said counter member in an advanced position for a predetermined time.

27. A circuit interrupter comprising, separable contacts, electroresponsive means having an armature movable in response to an overload, a counter member operable a predetermined distance to eifect separation of said contacts, means biasing said counter to return it to a normal position upon termination of the overload, means imparting one step of a step-by-step advance to said counter member each time the armature moves in response to an overload for eventually effecting movement for said predetermined distance, holding means operable to retain the counter member in an advanced position, means including a thermally-responsive time delay element operable to maintain the holding means in an operative position and actuated in response to current through the electroresponsive means to release said holding means to an inoperative position a predetermined time after normal energization of the electroresponsive means, and means for preventing separation of said contacts while the armature is moved in response to an overload.

ANDREW W. EDWARDS. JAMES M. WALLACE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,982,986 Garlington Dec. 4, 1934 2,308,660 Koujoumjiah Jan. 19, 1943 2,414,786 Lincks et al. -1 Jan. 21, 1947 2,452,233 Gerard et al. Oct. 26, 1948 2,468,851 Wallace May 3, 1949

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