US1954849A - Automatic reclosing circuit breaker - Google Patents

Description

April 17, I934. R. s. SEESE 1,954,849

AUTOMATIC RECLOSING CIRCUIT BREAKER Filed Aug. 27', 1950 3 Sheets-Sheet l I INVENTOR ATTORNEYS April 17, 1934.

a a 22 42 94 y R. S. SEESE AUTOMATIC RECLOSING CIRCUIT BREAKER Filed Aug. 27, 1930 3 Sheets-Sheet 3 INVENTOR flAEr/S 59659) ATTO R N EYS Patented Apr. 17, 1934 PATENT -OFFECE 1,954,849 AUTOMATIC aacnosnvc. omourr BREAKER Robert S. Scene, Detroit, Mich. Application August 27, 1930, Serial No. 478,007

11 Claims. (Cl. 175-294) My invention relates to mechanism "for the automatic operation of a circuit breaker.

The object'of my invention is to provide a simple, inexpensive, and reliable device which will open a circuit breaker upon the occurrence of abnormal conditions in circuit, reclose the circuit breaker after a predetermined time interval, repeat the above operations if the abnormal conditions continue, and finally, if the abnormal conditions persist, leave the breaker in open position after a predetermined number oi. opening and closing operations.

A further object of my invention is to provide a device, as described above, without any relay or relays to control the reclosing function, or to limit the number of reclosing operations, but with mechanical features to control such reclosing and limiting functions, thus decreasing the liability of failure.

A further object of my invention, is to provide a device, as described above, in which the reclosing mechanism, the timing mechanism which controls the reclosing functiomthe limiting mechanism which limits the number of reclosures and, if desired, a resetting mechanism which resets the timing and limiting mechanism to their initial positions should the abnormal conditions in the circuit disappear before the limiting mechanism has functioned are all driven from a common 30 motor.

Other objects will appear in the further and more detailed consideration of the invention.

A circuit breaker is included in an electric circuit in order to interrupt such circuit when desired. An automatic circuit breaker, so-called, is designed to open automatically when overload or short circuit conditions of predetermined intensity appear in its circuit. An automatic reclosing circuit breaker not only opens automatically, as just described, but is provided with means for reclosing automatically after a predetermined time interval, .on the assumption that the abnormal conditions causing the breaker to open will have disappeared. If such conditions have not disappeared when the breaker recloses,

it will again open automatically, and again reclose after a certain elapsed time. Additional trippings and reclosures will occur as long as the abnormal circuit conditions persist, unless some limiting device is provided to limit the reclosures to a predetermined number. Usually there is a means of restoring the limiting device to its initial position should the abnormal circuit conditions disappear before the predeter mined number of reclosures has been made.

Such restoring. means will enable the circuit breaker to reclose the full predetermined number of times, should any abnormal circuit condition appear subsequently. If, however, the abnormal conditions persist until the full predetermined 00 number of reclosures has been made, the limiting device will cause the circuit breaker to remain in open position until it is restored manually, at which time the limiting device can be returned to its initial position. No invention is claimed for the elements described in this paragraph, the automatic reclosing circuit breaker with provision for locking open after a predetermined number of reclosures having been described fully in Thomson Patent No. 508,652 dated November 14, 1892. The invention about to be described is an improvement on existing methods of accomplishing these results, and eliminates certain undesirable features.

It is at once obvious that, from its very nature, the fully automatic reclosing circuit breaker will usually operate unobserved. Since it is designed to operate in emergencies, or under abnormal conditions, it is imperative that its operation be as reliable as possible. It is essential, therefore, that any delicate parts, such as small timing contacts, relays, dashpots, coil windings apt to be affected by lightning or abnormal voltages be omitted wherever possible, or at least replaced by sturdy parts not likely to cause trouble. In the invention under consideration, reliance is placed on simple mechanical parts not easily subject to climatic or circuit conditions, and operated by a common driving means of suflicient power to perform the various functions positive- 1y, even after long periods of idleness. The employment of common driving means, moreover, gives proper synchronization of the various elements of the mechanism where this is desirable.

Of the accompanying drawings, which serve to show schematically in side elevation my mechanical means for automatically-opening and closing a circuit breaker for limiting the number of reclosures on any single case of load circuit trouble, and for resetting the reclosure limiting device,

Figure 1 indicates the initial or "closed position of the circuit breaker and of its operating mechanism;

Fig. 2 shows the approximate position of parts just after circuit breaker is thrown into open position;

Fig. 3 also shows the breaker in open position just prior to being reclosed for the first time,

as indicated by Fig. 4 which shows the position of mechanism before a second opening of breaker takes place;

Fig. 5 shows the breaker locked in open position after the predetermined number of reclosures have taken place and before the mechanism has been returned to its normal or initial posi-' tion, as indicated in Fig. 1.

Similar parts of all drawings are indicated by the same reference figures, as follows:

With the exception of current transformers 5, tripping coils 30, and motor 24, no electrically energized elements are employed in connection with my breaker operating and controlling mechanism, which presents a combination of purely mechanical elements actuated from a powerful common source of motion, greatly decreasing the liability of failure.

As indicated by the drawings, an electric generator 1 supplies current to an external circuit 2 through a circuit breaker 3 to a load circuit 4 wherein current transformers 5 are placed. The circuit breaker 3, normally biased to open by gravity and by pull of spring 6, is held in closed position by a toggle joint 7, one end 8 of the joint being attached to bell-crank lever 9, while the other end 10 is connected to the end of a lever 11 held against upward movement by a stop 12. One end of lever 11 is bent upwardly to ride lightly on the circumferential surface of a timing disk 14 to which a concentrically-disposed notched actuating wheel 15 is fixedly attached. This wheel is normally moved in a clockwise direction against the pull of spring 16, while an oppositely-disposed notched resetting wheel 1'7 is moved in a counter clockwise direction against the pull of a spring 18. Both wheels are adapted to be independently rotated by the pawl 19 carried by a rod pivotally attached to lever 20, a retracting spring 21 normally holding lever 20 in contact with stop 22. I

The breaker closing mechanism comprises a cam member 23 adapted to be rotated in clockwise direction by the motor 24, which is driven from a conventionally illustrated source of energy 25, the motor circuit being closed through switch 26 when the breaker 3 opens. When overloading of predetermined intensity occurs, a pivotally-mounted hammer-like member 27, normally held in inactive position by latch member 28. is released, energization of the tripping coils 30 by current delivered thereto by the-current transformers 5 serving to pull the latch 28 away from the holding end of lever 27, which is then quickly forced upwardly by the spring 29, striking toggle '7, breaking it and thus allowing breaker 3 to open under the influence of gravity and pull of spring 6.

With the line protected by the circuit breaker in its normal condition, the elements represented by the schematic showing will be in the positions of Fig. 1, in which the circuit-breaker 3 is closed and held in such position by the linkage 11 which includes the toggle '7. Since both make and break points 26 and 3'7 are open, the motor circuit is inactive. Timing disc 14 and its wheel 15 are in the inactive position, having been returned by its spring at the close of the previous advance of wheel 17 by pawl 19 through the release action of latch 36, pawl 19 continuing to hold wheel 17 in such completed position with spring 18 under tension.

Assuming an abnormal condition developing in the line being protected, the trip mechanism represented by coils 30 are made active to release latch 28, whereupon spring 29 causes hammer 27 to move forcibly into contact with the toggle and break the latter, thus permitting the circuit breaker to move to open position, the support therefor provided by the linkage being made inactive as a support. The movement of the cir cuit breaker to open position operates arm 9 and through it, pawl 19 is shifted into contact with wheel 15, releasing wheel 1'7 and permitting the latter to return to its inactive position by action of spring 18, the movement of the pawl 19 having released a latch 38 from engagement with wheel 1'7.

The movement of the circuit breaker to its open position permits the latter to close make and break point 26 of the motor circuit, as indicated in Fig. 2, thus beginning operation of the motor 24 and cam 23 which, during its initial rotation returns hammer 27 to its latched position out of the path of travel of cam 23. Also, this movement of the cam, and each succeeding rotation, causes it to contact with and move arm 20 on its pivot against the tension of spring 21, thus moving pawl 19 downward a distance of a stepwhich may be one or more teeth of wheel I 15-50 that when the cam passes the arm, spring 21 serves to move the pawl upwardly and thus advance wheel 15 one step from its inactive position. This action continues with each cam rotation until the advance of wheel 15 brings the first of the slots 31 of the timing disk 14 into position where the upwardly-turned end 13 of the linkage is free to enter the slot, whereupon the weight of the collapsed linkage causes the linkage to collapse downwardly as permitted by the end 13 entering the slot, as indicated in Fig. 3, thus bringing the linkage also within the path of travel of 'cam 23 and at the same time straightening the toggle. As a result, the cam 23 during its rotation, contacts with-the linkage and raises it to the position of Fig. 4, thus moving the lower end of hell crank lever 9 in a direction to reclose the circuit breaker, and at the same time shift pawl 19 into engagement with wheel 1'7.

However, the parts are so arranged that pawl 19 remains in engagement with the tooth of wheel 15' sufliciently long as to permit spring 21 to give an upward impulse to pawl 19, after the cam has released member 20, this taking place before the cam disengages the linkage, the direction of movement of end 13 being such that advance of wheel 15 can be had without damaging of parts during upward travel of the linkage after the cam has left arm 20. Hence, wheel 15 will have been advanced one step, so that the end 13 does not re-enter the slot 31 when the cam has shifted the linkage to the position of Fig. 4.

At this point it should be noted that the motor circuit also includes a second make and break point represented by a pivoted arm 37 connected to one side of the circuit and extending into the path of travel of a pin 4'7 carried by disk 14, said arm 3'7 co-operating with a contact connected with the other side of the motor circuit. The two points 26 and 3'7 thus indicate a pair of make and break points in the motor circuit with the points arranged in parallel. In Fig. 1, arm 37 is shown as held out of contact by pin 4'7, so that under normal operating conditions, both make and break points are broken. When, however, wheel 15 begins its advance, pin 47 is moved from its supporting position to arm 3'7, the latter then moving to close this second make and break point, this point remaining closedand completing the motor circuit throughout the period during which wheel 15 and timing disc 14 remain out of the inactive position of Fig. 1.

Hence, when the circuit breaker has been reclosed by the movement of the linkage by the cam, as above describedthus opening the first make and break point 26, the motor circuit remains complete because of the closed second point 37. Hence, the motor continues in operation and cam 23 continues its operations on arm 20 and providing impulses to pawl 19; since the latter is now in contact with wheel 17, the latter will advance, a latch 38, heretofore referred to, being held in contact with the wheel by spring 41, to prevent return movement of the wheel under the action of spring 18. If the return of the circuit breaker finds the line free from the abnormality, wheel 17 will continue to advance step-by-step until its rotation brings a member 35 carried by the wheel into engagement with a latch 36-normally active to prevent retrograde movement of wheel 15 by the action of a spring 42whereupon member 35 operates latch 36 to release wheel 15, the latter then being free to return to its inactive position through the action of spring 16, the close of this movement causing pin 47 to raise arm 37 and break the motor circuit and thus stop the motor.

If, however, the return of the circuit breaker demonstrates that the abnormality persists, its presence will again render the tripping mechanism active to release latch 28, with the result that the toggle is again brokenand the cycle of operations described again repeated but with certain changed conditions. Since the repetition of the cycle begins before wheel 17 has completed its revolution, wheel 15 remains in the position it occupied when pawl 19 was previously released from engagement therewithbeing held by latch 36and hence make and break point 3'7 is still closed with the motor operating. Breaking of the toggle shifts pawl 19 into engagement with wheel 15, the movement releasing latch 38 from engagement with wheel 17 through engagement of arm 39 with pin 40 of the latch, with the result that wheel 1'7 is free to return under the action of spring 18, the return movement continuing until member 35 engages stop 46, this position representing the inactive position of wheel 17, the latter thus being in position to again advance to make the complete revolution previously referred to. It should be noted that wheel 17 can make such complete revolution only when the circuit breaker remains in its closed position sufliciently long to permit the wheel step-by-step advance to complete the revolution; if the advance is interrupted by the opening of the circuit breaker, the wheel automatically returns to its inactive position as above indicated, thus being ready to begin such advance for the complete distance. The wheel thus presents a definite time characteristic made manifest only when the line is free of abnormalities for a period designed to be sumcient to indicate stability of the line after temporary abnormality conditions. At the close of such complete period, it functions to re-set the operating system by opening the way to a return of the timing means to its inactive position and the breaking of the motor circuit at 37.

Another distinction is in the position of wheel 15, which, as before pointed out, has not returned to its inactive position-wheel 1'7 not having completed its revolution before the circuit breaker again opened. The end 13 of the linkage rides on the circular face of disk 14' beyond the first slot 31, so that as cam 23 continues to set up the pawl impulses by its actuation of arm 20, the engagement of pawl 19 with wheel 15produced by the breaking of the togglecauses the wheel 15 to again advance step-bystep until the second slot 31 comes into position to receive the end 13, whereupon the previous circuit breaker re-closing cycle again takes place, as before described, pawl 19 being shifted to wheel 1'7 to again begin the advance of the latter; the reclosing action removes end 13 from the slot, with the step advance of wheel 15, as before described, thus leaving the parts ready for the final re-setting action if the circuit breaker remains closed sufiiciently long to permit wheel 1'? to make it: complete revolution.

If however, the abnormality persists, the cycle referred to is repeated with end 13 passing into the third slot 31, as wheel 15 is further advanced, wheel 17 having again returned to inactive position, thus setting the mechanism for a third reclosing of the circuit breaker with the wheel 17 again beginning its advance. The time disk 14, as shown, is designed to permit three reclosures of the circuit breaker, and since the spacing of the slots 31 represents a definite time characteristic due to the conditions of the stepby-step advance of wheel 15, the reclosures well have a definite interval characteristic. It is considered with this arrangement that three reclosures would be sufficient to demonstrate the presence of a persistent abnormality which required manual correction, and hence the disclo sure simply indicates the three slots.

Should the reclosure, however, disclose the presence of a continued abnormality thus indicating a persistent condition, the succeeding development of the cycle by breaking the toggle causesadvance of wheel 15 until a stop 33 thereon contacts with a stop 34, thus preventing further advance of wheel 15, pawl 19 then idling until the system receives manual attention, arm 37 retaining the motor circuit active since wheel 15 prevents collapse of the linkage to the position of Fig. 3, and prevents activity of pawl 19 with wheel 17, thus preventing development of the cycle which would release latch 36 and permit wheel 17 to return wheel 15 to its starting or inactive position, essential if arm 3'7 is to open the motor circuit. The circuit breaker therefore remains open and the motor and cam continue their rotations awaiting the manual activities to restore the line conditions to normality and reset the operating mechanisms.

The schematic representation of pawl 19 in this manner indicates one of the characteristics of the invention, viz: the advancing activity of either wheel 15 or 1'7 can take place only during the similar inactivity of the other wheel, since, in the showing, pawl 19 can be active with but one wheel at a time. The two wheels provide essentially different timing activities, and the control of the start and ending of activities is therefore necessary to prevent concurrent advancing activities. Wheel 15 is active in its advance only when the circuit-breaker is open, while the advancing activity of wheel 1'7 is limited to periods when the circuit-breaker is closed, the service of wheel 15 being to determine howlong the breaker shall remain open before attempting to reclose it, while wheel 1'7 serves to determine if the line conditions have changed to such an extent as to presumably ensure continued line activity under normal conditions. It is obvious, of course, that if individual pawls for the wheels be employed, the same characteristic condition is provided by rendering one pawl inactive to advance its wheel during the period when the other pawl is active in advancing the other wheel, this being the teaching provided by the particular pawl arrangement shown, in which the double pawl is limited to activity with but one wheel at a time.

As will be understood, the system sets up the condition of a normal cycle which may or may not be completed, each cycle starting with the opening of the circuit-breaker and ending with the resetting operation provided after the circuitbreaker has remained closed for a definite period after re-closure. If but one cycle is required to restore the line to normal conditions, the cycle is completed from beginning to end after once starting. If the abnormality persists, the cycle development is interrupted and a new cycle started, the elements, with the exception of the timing disk and the motor and cam being restored to the initial positions prepared to perform its share in the cycle development. In effect, however, the only change with respect to the timing element at the beginning of the second cycle is that it has not returned to its initial starting position to open the motor circuit-otherwise, the cycle development is similar to the initial development, since the reclosing action has simply substituted a second segment of the wheel 15 for the first .segment used in the initial cycle, the cycle development thus being similar to the first. The other changed condition is in the motor circuit. At the start of the first cycle the motor and cam were inactiveat the start of the second cycle, the motor and cam are in active operation, having continued operation when the first cycle was interrupted.

This same condition will be present if the second cycle is interrupted, thus duplicating the initial cycle conditions withthe exception of the changes indicated. With the third reclosure of the circuit-breaker ineffective in presence of a continuance of the abnormality, the latter is considered as persistent and requiring manual attention, and when the cycle is then interrupted by contact of stops 33 and 34, no further attempts are made to produce automatic reclosing, the cycle remaining interrupted until manual attention restores the various elements to their in itial positions.

From this it will be seen that the elements are always ready to begin the cycle when the line conditions call for its development, with the cycle of similar characteristic in each case, except for the changes indicated. Consequently, it is possible to provide a predetermined variation in the cycle development by the spacing of slots 31, permitting a variation in the time-length during which the circuit-breaker will remain open in successive cycles. This is of advantage in that the second time-length can be made longer or shorter than the first, and the third be varied from the others, etc.; this is made possible by the fact that wheel 15 is not required to move to its initial position to develop the second cycle, so that the re-setting portion of the cycle can be interrupted at any point and yet serve to place the system ready for the beginning of a second and third cycle, if necessary. With the permanent interruption present, the line obviously requires manual attention and the completion of the cycle development is unnecessary.

This advantage is due in part to the fact that they motor-driven cam is itself no part of the timelength controlling structure-the cam simply acts to impart movements to certain elements, and hence can be rapidly rotated, so that its particular location at the instant of beginning the cycle is unimportant, it quickly reaching the position of the parts which it is to actuate and starting the cycle. And the fact that the motor and cam continue operation after reclosing ensures an instant response by the cam if the second cycle is required. Because the cam can be given these rapid movements, an additional advantage is present through the fact that the hammer is immediately re-set, and the re-closing movement of the circuit breaker is not only by motive power but is made quickly, giving assurance that the circuit breaker will remain in its open position the maximum length of time and then be snapped back to closed position. The cam itself thus presents characteristics of the inherent qualities of the motor as to timing action; since the motor runs at a substantially uniform speed, the cam completes its revolution in substantially uniform periods, ensuring that the step-by-step movements of the timing wheels will be at regular intervals of time, and thus ensuring greater accuracy in the timing.

As will be seen, the only solenoid controlling structure is the tripping solenoids 30, these being the only control elements of the system which are dependent for operation on the actual current flow; the two make and break points of the motor circuit are mechanical control elements which simply open and close the circuit mechanically. Make and break point 26 is an intermittent closure, while point 37 is a sustaining closure, the two points being arranged in parallel, point 26 determining the beginning of the initial motor operation and point 37 determining the ending of this operation, the motor remains active during the interim; when the system reaches the "lock-ou condition of Fig. 5, both points are closed and remain so until the system is manually restored.

Wheels 15 and 17 are both latch-controlled to prevent returning action after pawl advance. These latches-36 and 38-are made active at proper times, but rendered inactive when either wheel is to return to its initial inactive position. It is the control of these which determines the latter portion of the cycle development to ensure that wheel 15 will not return to its initial inactive position and break the motor circuit before wheel 1'7 has completed its time-length activities to indicate that the line conditions have returned to normal.

In these schematic views, a connection 45 connects bell-crank lever 9 with the arm which carries pawl 19, thus indicating a synchronous movement of the two elements to ensure that the pawl will be inactive with the timing wheel 15 when the circuit breaker is closed and active with this wheel when the circuit breaker is open, other than during the period in which the wheel is advanced the single step at the time the reclosing takes place, as heretofore pointed out.

As pointed out, the motor circuit remains open the initial contact at point 26 is made by the open circuit breaker. Assurance is thus had that none of the timing operations will begin in advance of opening of the circuit breaker initially and ensuring that the system activities may not be inaugurated excepting in presence of an actual break in the line circuit provided by opening the circuit breaker. In addition, assurance is had that the breaker will remain open for a definite time before re-closing, the time of reclosing being positively determined by the timing wheel 15, the actual reclosing movement being in immediate response to the entrance of end 13 into slot 31.

And it will be noted that while the motor circuit activity is initially dependent on the opening of the circuit breaker, the close of motor operation is not determined by the motor itself. The movement of arm 37 to open the motor circuit is dependent on the return of wheel 14 to its initial position after having been moved out of such position, and the movement back to initial position is in a direction opposite to the direction of movement of the wheel provided by motor activity. Hence, assurance is had that motor activity will continue until the system has been completely re-set under the automatic operation, or until rendered inactive by the manual re-setting activities. In other words, the motor is rendered active to operate the cam 23, the movements of the latter being utilized to produce certain activities within the system by the successive rotations of the cam, the number of which is immaterial since Other advantages are present, the above illustrating a few which are of especial importance.

What I claim is:

1. In automatic circuit breaker operating systems adapted for the protection of line circuits, wherein abnormal conditions in the line circuit will open the latter and concurrently establish a motor-operating circuit to produce activity of a motor, and wherein a trip mechanism rendered active by such abnormal conditions initiates the line circuit breaking action, a circuit breaker movable between open and closed positions, a cam driven by the motor, mechanism including a toggle for supporting the circuit breaker in closed position and co-operative with the cam in re-closing the circuit breaker, an element adapted to break the toggle when the trip mechanism is rendered active, a normally-inactive timing instrumentality rendered active by cam movements and co-operative with the breaker reclosing mechanism for controlling the movements of the latter into the path of cam travel, said instrumentality being operative to provide a succession of such mechanism movements with predetermined time intervals therebetween, a system re-setting instrumentality having a cycle to provide a predetermined maximum time period of activity with the cycle development provided by cam movements and responsive to reclosing movements of the circuit breaker, and mechanical operative connections between said instrumentalities to permit return of the timing instrumentality to its inactive position upon the completion of the cycle of the re-setting instrumentality.

2. A system as in claim 1 characterized in that the reclosing mechanism includes a linkage of which the toggle forms a part, said linkage normally supporting the circuit breaker in its closed position and permitting opening of the circuit breaker when the toggle is broken, said linkage being collapsible under timing instrumentality control to straighten the toggle and locate the linkage in the path of cam movement to reset the co-operative with the reclosure mechanism to permit a corresponding number of reclosures of the circuit breaker, the operative connections between the instrumentalities including a latch operative with the ratchet wheel to prevent return movement of the wheel prior to latch release by the re-setting instrumentality, said reclosing mechanism being operative to render the pawl inactive relative to the wheel when the circuit breaker is in closed position.

4. A system as in claim 1 characterized in that the re-setting instrumentality includes a ratchet wheel, a pawl for advancing the wheel step-bystep, an operating member for the pawl extending in the path of travel of thecam andoperamovable intdand'out-of engagement with the ratchet wheel and operative to prevent return of the latter when engaged therewith, activity of the pawl and latch being determined by the re clQSing mechanism with the pawl inactive with the wheel during periods of activity of the timing instrumentality.

5. In automatic circuit breaker operating systems adapted for the protection of --line circuits,

wherein abnormal conditions in the lihehircuit,

will open the latter and concurrently establish a motor-operating circuit to produce activity oi. a motor, and wherein a trip mechanism rendered active by such abnormal conditions initiates the line circuit breaking action, a circuit breaker for the line circuit, circuit-breaker position-retaining and reclosing means including a collapsible breaker-supporting instrumentality normally active to retain the breaker closed and movable to' collapsing position and permit breaker opening by trip mechanism activity, a rotatable actuator driven by the motor, a normally-inactive reclosure timing instrumentality adapted to be rendered active responsive to such abnormal line circuit conditions, a resetting instrumentality having a definite time period of normal activity in succession to reclosing movements of the circuit breaker and adapted to complete such period in presence of normal line circuit conditions, said instrumentalities being co-related mechanically to produce a normal succession of activities in which initial collapse of the supporting "instrumentality active for a predetermined period upon termination of which the supporting instrumentality is rendered active by the rotating actuator to reclose the breaker and begin activity of the resetting instrumentality, the co-relation oi the instrumentalities being such that a persistence of the abnormal line circuit conditions discontinues the activity 0! the resetting instrumentality and restores the latter to its initial position and repeats the normal succession of activities, said rotating actuator being active as the power source for timing activities with the activity limited to intermittent co-operation during instrumentality activity of the two timing instrumentalities to provide step-by-step movements of such instrumentalities during timing activities.

6. A system as in claim 5 characterized in that 100 tive in providing the ratcheting cycle, a latch the breaker supporting instrumentality movements between breaker-supportingposition and collapsed position in which the breaker is in lineopen position, present the following cycle: initial collapse of the instrumentality by the trip mechanism, cooperation with the timing instrumentality for a predetermined period to retain the supporting instrumentality inactive with the rotating actuator during a predetermined period at the close of which the timing instrumentality permits further collapse of the supporting instrumentality to become active with the actuator to concurrently restore the instrumentality to breaker supporting position and render it inactive with the timing instrumentality.

7. A system as in claim 5 characterized in that"the initial activity of the trip mechanism positions an element of the latter within the path or travel of the rotating actuator to immediately restore the trip mechanism to operative position by actuator movement'while the circuit breaker is in open position.

8. A system as in claim 5 characterized in that the timing movements of the timing instrumentality are rotative in constant direction away from the normally-inactive position of the instrumentality and include a succession of stages of definite time characteristic, the activity of each stage being dependent upon and made in response to the previous initial collapse of the supporting instrumentality.

9. A system as in claim 5 characterized in that the timing movements of the timing instrumentality are rotative in constant direction away from the normally-inactive position of the instrumentality and include a succession of stages of definite time characteristic, the activity of each stage being dependent upon and made in response to the previous initial collapse of the supporting instrumentality, return of the timing instrumentality to its normally-inactive position being dependent upon and responsive to completion of the time period of activity of the resetting instrumentality.

10. A system as in claim 5 characterized in that the step-by-step movements of the timing and resetting instrumentalities are responsive to rotative movements of the actuator and are nonconcurrent.

11. A system as in claim 5 characterized in that the timing movements of the timing instrumentality are rotative in constant direction away from the normally-inactive position of the instrumentality and non-responsive to the resetting instrumentality activity, the return of the timing instrumentality to normally-inactive position being dependent upon and responsive to completion of the time-period of activity of the re-setting instrumentality.

ROBERT S. SEESE.

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