US3250876A

US3250876A - Reset means for automatic protective devices

Info

Publication number: US3250876A
Application number: US369404A
Authority: US
Inventors: Blaine H Schultz; Kazuo H Date
Original assignee: McGraw Edison Co
Current assignee: McGraw Edison Co
Priority date: 1964-05-22
Filing date: 1964-05-22
Publication date: 1966-05-10
Anticipated expiration: 1983-05-10

Description

y 1966 B. H. SCHULTZ ETAL 3,250,876

RESET MEANS FOR AUTOMATIC PROTECTIVE DEVICES 2 Sheets-Sheet 1 Filed May 22, 1964 w w a I mm W mm; W mm w mg) fi 5 m a N M BK M m y 1966 B. H. SCHULTZ ETAL 3,250,876

RESET MEANS FOR AUTOMATIC PROTECTIVE DEVICES 2 Sheets-Sheet 2 Filed May 22, 1964 JNVENTORS. 5mm. H, 509 04 72 K0200 2/. 17/475 BY fiztorflgf United States Patent C 3,250,876 RESET MEANS FOR AUTOMATIC PROTECTIVE DEVICES Blaine H. Schultz and Kazuo H. Date, both of South Milwaukee, Wis, assignors to McGraw-Edison Company, Milwaukee, Wis, a corporation of Delaware Filed May 22, 1964, Ser. No. 369,404 16 Claims. (Cl. 200-89) This invention relates to automatic protective devices and, more particularly, to a hydraulic control mechanism for automatic protective devices, such as repeating circuit interrupters.

Because the majority of faults in electrical distribution systems are temporary in nature, and will clear in a relatively short time, it is common to protect such systems with repeating circuit interrupters, or reclosers, which are constructed and arranged to execute a series of successive opening and reclosing operations during which time such temporary faults will normally clear. If the fault does not clear during a predetermined number of such operations, usually three, it is considered permanent and the recloser lock-s itself open so that the permanent fault is isolated from the source.

It has been found, however, that in some systems up to 30% of the recloser lockouts experienced were due to rapidly successive, non-permanent faults. For example, during lightning storms the recloser may experience a series of rapidly successive non-permanent and self-clearing faults which will cause it to cycle to lockout even though no permanent fault exists in the system. Thus, unnecessary outages and circuit discontinuities may result even though it is not necessary for the recloser contacts to open permanently.

It is an object of the invention to provide an automatic protective device with means for distinguishing between permanent and non-permanent faults.

Another object of the invention is to provide an automatic protective device having lockout means and integrating means operable after a predetermined number of occurrences of an abnormal circuit condition to actuate said lockout means, means for resetting the integrating means after a time delay, and means operable to effect more rapid resetting of the integrating means if the abnormal condition does not reappear in the system after the appearance and disappearance thereof.

A more specific object of the invention is to provide a repeating circuit interrupter having overload responsive means for opening switch means upon the occurrence of an overload circuit condition, switch closing means operable after a switch opening operation, lockout means, operating counting means operable after a predetermined number of switch opening operations to actuate the lockout means, .and means coupled to the overload responsive means and to the operation-counting means for resetting the operation counting means if the main contacts close on a non-faulted system.

These and other objects of the instant invention will become more apparent from the detailed description thereof taken with the accompanying drawings wherein:

FIG. 1 is a side elevation view, with parts broken away,

of a repeating circuit interrupter incorporating the instant invention;

FIG. 2 is a view taken along lines 22 of FIG. 1; FIG. 3 is a view taken along lines 3-3 of FIG. 2; FIG. 4 is a view taken along lines 44 of FIG. 2; and FIG. 5 is a fragmentary sectional view illustrating the operation of the resetting means according to the instant invention.

Referring now to the drawings in greater detail, FIG. 1 shows a repeating circuit interrupter or recloser inice corporating the instant invention and including a metallic housing or tank 11 which is closed at its upper end by a .gasketed cover 13 from which the internal operating mechanism is suspended on insulating supports 14. The tank 11 is ordinarily filled with dielectric fluid, such as oil, to the level indicated by the dash line 15.

The cover 13 also supports a pair of insulating bushings 16, only one of which is shown in FIG. 1. The bushings 16 extend interiorly of the tank 11 and beneath the oil level 15 for serially connecting the recloser 10 in the system being protected. As seen in FIG. 1, the current path between the bushings 16 and through the recloser 10 constitutes a series circuit which includes an electromagnetic operating coil 17 and an interrupting switch assembly generally designated by the reference numeral 18.

In order to correlate the various portions of the repeating circuit interrupter 10 shown in FIG. 1, its operation will now be discussed in general terms. Each time an overcurrent occurs in the system being protected, an electromagnetic plunger 19 is attracted downwardly into the series connected operating coil 17 to move an operating rod 20, connected to its lower end, into engagement with an overcenter operating mechanism 24 of the interrupter switch 18. This pivots a movable contact arm 21 around a pin 26 and to its open position. With the interrupting contacts 18 open, the series coil .17 is deenergized so that the overcenter mechanism 24 elevates the electromagnetic plunger 19 to rotate the contact arm 21 counterclockwise into its closed position.

Although the details of the overcenter mechanism 24 form no part of the instant invention, it will now be briefly described so that the operation of those portions of the repeating circuit interrupter 10 which comprise the instant invention can be more easily understood. As seen in FIG. 1, the lower end of the rod 20 rests on a roller 99 carried at one end of a lever 100, the other end of which is pivotally mounted on a fixed pin 101. A longlink 102 is connected at one end to the lever and extends downwardly therefrom where its opposite end is connected by a pin 107 to one end of a short link 105 Whose other end is provided with an elongate slot 103 for slidably engaging a fixed pin 104. An overcenter spring 106 extends between the pin 107 and bracket members 108 extending upwardly from the contact arm 21. In addition, a link 110 pivotally mounted at 11-1 is coupled to the pin 107. When the circuit interrupter is in its closed position, shown in FIG. 1, the spring 106 exerts an upward force on spring 102 to hold the plunger 19 in its elevated position.

As will be described more fully hereinbelow, each time the magnetic plunger 19 is depressed upon the occurrence of an abnormal circuit condition, an insulating stem 22 connected to its upper end is operative through the agency of a bell crank 23 to depress a pump piston 25 so that a measured quantity of hydraulic fluid is delivered to a hydraulic integrating mechanism 27. Upon each pumping operation, a stem 28 extending outwardly from the integrating mechanism 27 is advanced a predetermined distance toward a trip finger 29. After a predetermined number of such switch opening and reclosing operations, the stem 28 will engage the finger 29 to release the overcenter lockout mechanism 30 which in turn will engage the crank 23. This rotates the crank 23 counterclockwise so that the magnetic plunger 19 is held in its depressed position to prevent closure of the main interrupting contacts 18 until they are manually reset.

Certain of the various details of the repeating circuit interrupter just discussed form no part of the instant invention and, accordingly, will not be discussed in detail for the sake of brevity. For a more complete description of these details, reference is made to Patent 2,926,228 which is assigned to the assignee of the instant invention.

As seen more particularly in FIG. 3, the magnetic plunger 19 descends through a bore 35 formed in a casting 31 which also contains the pump piston 25 and the integrating assembly 27. A dashpot cylinder 37 is disposed coaxially with the bore '35 for receiving magnetic plunger 19 and is formed by the insulating spool 38, upon which a series operating coil is wound. An aperture (not shown) is provided in the lower end of dashpot cylinder 37 to allow the operating rod 20 to pass therethrough for engagement with the overcenter assembly 24 as discussed hereinabove. The magnetic circuit for the flux emanating from the coil 17 includes the plunger 19, the metallic casting 31, the metallic base plate 32 and metallic support brackets 33 which extend between the casting 31 and the plate 32. .The brackets 33 and insulating rods 34 support the coil 17 and the base plate 32 which, in turn, support the interrupting switch assembly 18.

The pump piston is disposed for reciprocal movement within a cylinder formed in the casting 31 and has a stem 41 extending upwardly therefrom and connected at its upper end to a pin 42 carried by one arm 44 of the bell crank 23. The other end of crank arm 44 is pivotally connected at 45 to the upper end of the plunger stem 22.

The lower end of cylinder 40 is connected by a semicircular duct 48 formed in the bottom of the casting 31 (see FIG. 2) with the lower end of an. integrating cylinder 50 which is part of the integrating mechanism 27. The duct 48 is sealed by a flat gasket plate 51 held against the lower end of the casting 31 by a circular washer plate 52 which is disposed between the spool 38 and the lower surface of the casting 31 and which has an aperture 53 for passage of the magnetic plunger 19.

A discharge duct 58 connects a slide valve cylinder 59 with the dashpot cylinder 37. When'the plunger 19 is attracted downwardly, fluid in cylinder 37 is displaced and discharged through the duct 58 and into the slide valve cylinder 59. A slide valve 60 is disposed at the upper end of the cylinder 59 and is normally biased against a shoulder 61 by a compression spring 62. During opening operations of the recloser,.fluid pressure developed by the descent of plunger 19 causes a disc valve 64 mounted adjacent the lower surface of the slide valve 60 to close an orifice 63 provided through said valve, so that slide valve 60 is elevated in opposition to compression spring 62. The elevation of slide valve 60 opens an escape port 65 which leads from the slide valve cylinder 59 .to open the upper end of integrating cylinder 50 so that fluid from the port 65 is free to discharge into the body of fluid within the tank 11.

A ball check valve connects the lower end of integrating cylinder 50 to the duct 48 to permit the easy ingress of fluid into cylinder 50 and to prevent the discharge thereof back into the duct 48. The integrating assembly 27 also includes a piston 71 which carries the stem 28 at its upper end and which is biased for return toward the lower end of the cylinder 50 by a return spring 72.

As seen in FIG. 4, elevation of the slide valve 60 also exposes one of a plurality of orifices 74 formed in an orifice plate 75 and which may be rotated into registry with a passage 76 opening into the cylinder 59.

In order to more fully appreciate the instant invention, 6

4 to the point where the upper ends of the slots 81 move past a shoulder 82 formed in the upper end of the bore 35, the slots 81 will be closed by the walls of said bore, so that retarded descent of the plunger 19 begins. The fluid forced from the dashpot cylinder 37 when the slots 81 are closed passes through the duct 58 forcing the slide valve 60 upwardly and escapes through the escape port 65.

The downward movement of plunger 19 will also pivot crank 23 counterclockwise to force stem 41 downwardly, thereby moving the pump piston 25 into the pump cylinder 40. Upon the initial descent of the pump piston, the hydraulic fluid in the lower end of the cylinder 40 will be discharged through a relief port 84 until the lower end of the piston 25 has been depressed sufiiciently to cover this opening as seen by phantom lines in FIG. 3. Thereafter, as the piston 25 descends, the fluid in the lower end of cylinder 40 will be delivered to the lower end of the cylinder 50 through the duct 48 and past the ball check valve 70. This moves the integrating piston 71 a predetermined distance upwardly against the return spring'72, so that the stem 28 is elevated a predetermined distance toward the trip finger 29 of the lockout mechanism 30.

The downward movement of the plunger 19 will also rotate link clockwise to force

links

102 and 105 downwardly as the link pivots counterclockwise to swing pin 107 in an are about point 111. This action continues until the roller 99 impacts a second roller 112 carried by the bracket member 108 to pivot the switch arm 21 clockwise. Simultaneously, the line of action of spring 106 moves past the pivotal axis of switch arm 21 whereupon the main switches snap counterclockwise, opening the interrupting contacts 18. Upon the disappearance of line current in coil 17, the overcenter spring 106 will tend to move the

links

102 and 105 upwardly, thereby elevating the plunger 19. This will continue until the upward movement of pin 107 brings the line of action of spring 106 past the pivotal axis of switch arm 21, whereupon the switch arm will again be in an overcenter position and will snap into its closed position. Should the fault reappear upon the closing of the main interrupting contacts 18, the plunger 19 will again be attracted downwardly to open the main interrupting contacts 18 and to depress the pump piston 25 in the pump cylinder 40 to deliver a second measured quantity of hydraulicfluid below the integrating piston 71, so that it will be moved a second distance toward the lockout finger 29. This will move the piston 71 to the point where it covers the escape port 65 in the slide valve cylinder 59.

Should the fault reappear after the second closing operation, the plunger 19 will again be retracted downwardly into the dashpot cylinder 37. However, its descent will be further retarded by the closing of the escape orifice 65, since the fluid displaced from cylinder 37 must now discharge through the relatively small opening 74 in the orifice plate 75.

After the interrupting contacts have been opened for the third time, they will again be closed by the action of the overcenter spring 106 described above Should the overload current appear for a fourth time, the

plunger 19 will again be attracted downwardly, causing a fourth measured quantity of fluid to-be delivered g from the pump piston 25 to the integrating piston 71,

which moves the stem 28 into engagement with the trip finger 29, causing the main contacts 18 to be locked in open position.

After lockout, the return spring, 72 will force the piston 71 downwardly toward the lower end of the cylinder 50 as the fluid beneath the piston is forced between the piston and the cylinder walls at a rate governed by the clearance distance therebetween. Because this resetting action will also occur to some degree between successive pumping operations, the descent of piston 71 toward its reset position must necessarily be slow so that it will not lose a count during a succession of opening operations which terminatesin lockout.

In the foregoing discussion, it can be seen how the recloser cycles to lockout upon the occurrence of a fault in the system which is not self-clearing by a series of successive opening and reclosing operations. However, it can also be seen that because the resetting action of piston 71 is slow, a rapid succession of nonpermanent faults would also cause the recloser to cycle to lockout, thus causing an undesirable interruption in service. For this reason, the dump valve assembly 88 is provided. 1

The dump valve assembly 88 includes a dump valve cylinder 89 formed in the casting 31 and a dump valve piston 90 reciprocally mounted within the cylinder 89. A stem 91 extends axially upwardly from the piston 90 and has a pressure member 92 rigidly fixed intermediate its ends. The member 92 has an outwardly extending flange 93 the lower surface of which is engaged by the upper end of a return spring 85 whose lower end abuts against a shoulder 86 formed in the upper end of the cylinder 89. The other side of the flange 93 is engaged by the lower end of a hollow rod 94 whose upper end is pivotally connected to the pin 42 (see FIG. 1).

A first opening 95 on one side of the cylinder 89 is connected by a tube 96 to the underside of the integrating piston 71 and a discharge port 97 on the opposite side of the cylinder 89 opens directly into the ambient fluid within the tank 11. A third opening 98 is provided in the lower end of the cylinder 89 and is covered by an orifice plate 114.

Upon the occurrence of an overcurrent through the coil 17, the plunger 19 will be attracted downwardly as described hereinabove to simultaneously depress the pump piston and the dump valve piston 90. There will be no initial pumping action because of the opening 84 in the pump cylinder 40. The pump cylinder and the dump valve cylinder 89 are proportioned, so that when the opening 84 in the pump cylinder 40 is covered by the piston 25 whereby a pumping action commences, the dump valve cylinder 90 will also cover the

openings

95 and 97, as seen by phantom lines in FIG. 3. Further downward movement of the plunger 19, which acts to depress the pump piston 25 so that a measured quantity of fluid will be delivered below the integrating piston 71, will also depress the dump valve piston 90 toward the lower end of cylinder 89 as the fluid therein is expelled past the orifice plate 114.

After the interrupting contacts 18 have opened to interrupt the fault current in the coil 17, the plunger 19 will be elevated toward its initial position to elevate the pump piston 25 and the rod 94 from their positions shown .by phantom lines in FIG. 5 to their positions shown spring 85 will be retarded.

Should the fault be permanent in nature, so that it immediately reappears in the coil 17 upon the closing of the interrupting contacts 18, the plunger 19 will immediately be drawn downwardly to initiate a second pumping operation and to bring the lower end of the rod 94 into engagement with the flange 93 to return the partially raised piston 90 to the lower end of the cylinder 89. Thus, the

openings

95 and 97 in cylinder 89 will remain closed. As a result, the integrating piston 71 will remain in an elevated position after the first switch opening operation and will immediately be elevated at second increment upon the occurrence of the second switch opening operation. In this manner, the device will cycle to lockout as described hereinabove, upon the occurrence of a permanent fault in the system.

On the other hand, if the fault is not permanent and clears duringthe first switch opening operation, overload current will not appear in the coil 17 immediately upon the reclosing of the interrupting contacts 18 after the first switch opening operation. As a result, the dump valve piston 99 will continue moving upwardly under the influence of spring 85 after the interrupting contacts close so that the

openings

95 and 97 will be uncovered. This vents the lower end of the integrating piston 71 to the ambient fluid within the tank 11 so that the return spring 72 may immediately return the integrating piston 71 to its initial position. Thus, the integrating piston 71 is reset after the occurrence of a single non-permanent fault in the system, so that it will not be cycled to lockout upon the occurrence of a succession of such non-permanent faults.

The time required for the pump piston 90 to move from the lower end of the cylinder 89 and to uncover the

openings

95 and 97 will depend upon the force exerted by the spring and the leakage between the piston and the cylinder 89. This time will preferably be slightly longer than the normal time between successive opening operations during a permanent fault, so that the dump valve 88 will not prevent normal recloser operation. On the other hand, this resetting time delay will be much shorter than the time required for the spring 72 to reset the integrating piston 71.

While only a single embodiment of the invention has been shown and described, it is not intended to be limited thereby but only by the scope of appended claims.

Further, while the invention is illustrated with respect to a particular repeating circuit interrupter, it will be understood by those skilled in the art that it is also usable with other automatic protective devices such as automatic sectionalizing switches which employ similar hydraulic integrating means.

We claim:

1. An automatic protective device including switch means in circuit with the system being protected, lockout means operable to effect a continuous switch open condition, integrating means operable after a predetermined number of appearances and disappearances of an abnormal condition to-render said lockout means effective, resetting rneans normally operable to reset said integrating means, delaying means normally operable to delay the operation of said resetting means, and means including condition responsive means coupled to said system and operable to-render said delaying means ineffective to delay the operation of said resetting means if said abnormal condition does not reappear in said system after the appearance and disappearance thereof so that said integrating means is rapidly reset. p 2. An automatic protective device including switch means in circuit with the system being protected, abnormal condition responsive means coupled to said system, lockout means operable to elfect a continuous switch open condition, integrating means coupled to said abnormal condition responsive means and operable after a predetermined number of appearances and disappearances of an abnormal condition to render said lockout means eflective, reset means for resetting said integrating means, delaying means operable to delay the resetting of said integrating means by said reset means, and means coupled to said abnormal condition responsive means and to said integrating means and operable to render said delaying means inoperative to delay said resetting means to effect rapid resetting of said integrating means if said abnormal condition does not reappear'in said system after the appearance and disappearance thereof.

3. An automatic protective device including switch means in circuit with the system being protected, overcurrent responsive means coupled to said system, normally inactive lockout means operable to effect a continuous switch open condition, operation counting means having an initial position and being movable toward a final position for rendering said lockout means effective, means operable by said overcurrent responsive means to advance said operation counting means an incremental distance toward its final position upon each occurrence of overcurrent in said system, reset means for resetting said operation counting means in its initial position, delay means for delaying the resetting of said counting means by said reset means, and means coupled to said overcurrent responsive means and to said operation counting means and operable to render said delay means ineffective to delay the resetting of said counting means to effect the rapid resetting of said operation counting means if overcurrent does not reappear in said system after the appearance and disappearancethereof.

4. An automatic protective device including switch means in circuit with the system being protected, hydraulic integrating means, abnormal condition responsive means coupled to said system and to said hydraulic integrating means for actuating said integrating means upon each occurrence of said condition, normally inactive lockout means operable to effect a continuous switch open condition, said hydraulic integrating means being operable after a predetermined number of appearances of said abnormal condition to render said lockout means effective, reset means for resetting said integrating means, hydraulic time delay means for delaying the resetting of said integrating means, and valve means coupled to said overload responsive means and to said hydraulic integrating means for rendering said hydraulic time delay means ineffective to delay the resetting of said integrating means to effect the rapid resetting of said hydraulic integrating means if said condition does not reappear in said system after an appearance and disappearance thereof.

5. An automatic protective device including switch means in circuit with the system being protected, overcurrent responsive means coupled to said system, lockout means operable to effect a continuous switch open condition, a hydraulic cylinder, an integrating piston disposed in said cylinder, said piston being biased toward one end of said cylinder, means operable by said overcurrent responsive means to advance said piston an incremental distance toward the other end of said cylinder upon each occurrence of overcurrent in said system, said piston being effective to initiate the operation of said lockout means upon being moved a predetermined distance toward the other end of said cylinder, the biasing of said piston normally effective after a time delay to return said piston to the one end of said cylinder, and valve means disposed in said cylinder and coupled to said overcurrent responsive means and operable to effect more rapid resetting of said piston means if overload current does not reappear in said system after the appearance and disappearance thereof.

6. An automatic protective device including switch means in circuit with the system being protected, overcurrent responsive means coupled to said system, lockout means operable to effect a continuous switch open condition, a hydraulic cylinder, an integrating piston disposed in said cylinder, said piston being biased toward one end of said cylinder, means operable by said overcurrent responsive means to advance said piston an incremental distance toward the other end of said cylinder upon each occurence of overcurrent in said system, said piston being effective to initiate the operation of said lockout means upon being moved a predetermined distance, the biasing of, said piston being effective after a time delay to return said piston to the one end of said cylinder, and valve means coupled to said overcurrent rent in said system to prevent the operation of said valve means.

'7. An automatic protective device including switch means in circuit with the system being protected, hydraulic integrating means, abnormal condition responsive means coupled to said system and to said hydraulic integrating means for actuating said integrating means upon each occurrence of said condition, normally inactive lockout means operable to effect a continuous switch open condition, said hydraulic integrating means being operable after a predetermined number of appearances of said abnormal condition to render said lockout means effective, normally time delayed reset means for resetting said integrating means, and valve means having a valve element coupled to said overload responsive means and port means connected to said hydraulic integrating means, said valve element being movable into a position to close said port means upon the appearance of overload current in said system, means biasing said valve means away from said port means to effect more rapid resetting of said hydraulic integrating means if overload current does not reappear in said system within an interval which is shorter than the normal time delay of said reset means.

8. An automatic protective device including switch means in circuit with the system being protected, hydraulic integrating means, abnormal condition responsive means coupled to said system and to said hydraulic integrating means for actuating said integrating means upon each occurrence of said condition, normally inactive lockout means operable to effect a continuous switch open condition, said hydraulic integrating means being operable after a predetermined number of appearances of said abnormal condition to render said lockout means effective, normally time delayed reset means for resetting said integrating means, and valve means including a cyl nder and a piston disposed in said cylinder and coupled to said abnormal condition responsive means, discharge port means in said cylinder and connected to said hydraulic integrating means, said piston being movable into a position to close said port means upon the appearance of abnormal condition in said system, means biasing said piston away from port means to vent said hydraulic integrating means and thereby to effect more rapid resetting thereof if said condition does not reappear in said system within an interval which is shorter than the normal time delay of said reset means.

9. An automatic protective device including switch means in circuit with the system being protected, overcurrent responsive means coupled to said system lock-.

out means operable to effect a continuous switch open condition, a hydraulic cylinder, an integrating piston disposed in said cylinder, said piston being biased toward one end of said cylinder, pump means operableby said overcurrent responsive means for delivering a measured quantity of hydraulic fluid to the one end of said cylinder to advance said piston an incremental distance toward the other end of said cylinder upon each occurrence of overcurrent in said system, said piston being effective to initiate the operation of said lockout means upon being moved a predetermined distance, the biasing of said piston being effective after a time delay to return said piston to the lower end of said cylinder, and dump valve means having a valve element coupled to said overcurrent responsive means and port means connected to said cylinder, said valve element being movable into a position to close said port means upon the appearance of overcurrent in said system, means biasing said valve element away from port means to effect more rapid return of said piston to the lower end of said cylinder if overcurrent does not reappear in said system within an interval which is shorter than the normal time for said return.

10. A repeating circuit interrupter including switch means in circuit with the system being protected, switch opening means including overload responsive means coupled to said circuit, switch closing means operable:

after a switch opening operation, normally inactive time delay means for delaying the opening of said switch means, normally inactive lockout means adapted to be rendered effective for preventing the closure of said switch means, step-acting operation counting means coupled to said overload responsive means and operable after a first predetermined number of switch opening operations to initiate the operation of said time delay means, said operation counting means also being operable after a second predetermined number of operations to render said lockout means effective, normally time delayed reset means for resetting said operation counting means, first means normally effective to initiate rapid resetting of said counting means, and second means coupled to said overload responsive means and to said first means and operable to disable said first means after a switch opening and reclosing operation to effect delayed operation of said reset means if overload current reappears in said system, said second means being ineffective to disable said first means if overload current reappears in said system.

11. A repeating circuit interrupter including switch means in circuit with the system being protected, switch opening means including overload responsive means coupled to said system, switch closing means operable after a switch opening operation, normally inactive time delay means for delaying the opening of said switch means, normally inactive lockout means adapted to be rendered effective for preventing the closure of said switch means, operation counting means having an initial position and being movable a first predetermined distance to render said time delay means effective and a second predetermined distance to render said lockout means effective, means operable by said overload responsive means to advance said operation counting means incrementally away from its initial position upon each occurrence of overload in said system, normally time delayed reset means for resetting said operation counting means, first means normally operable to initiate the rapid resetting of said operation counting means, and second means coupled to said overload responsive means and to said first means and operable by said overload responsive means to disable said first means after a switch opening and a reclosing operation to effect delayed operation of said reset means if overload current reappears in said system, said overload responsive means being ineffective to operate said second means if overload current does not reappear in said system.

12. A repeating circuit interrupter including switch means in circuit with the system being protected, switch opening means including overload responsive means coupled to said system, switch closing means operable after a switch opening operation, hydraulic integrating means coupled to said overload responsive means and operable from an initial condition to initiate time delayed opening of said switch means after a first predetermined number of switch opening-operations and to prevent the reclosure of said switch means after a second predetermined number of operations, resetting means normally effective after a time delay to reset said hydraulic integrating means to its initial condition, valve means normally operable to initiate rapid resetting of said hydraulic integrating means, and disabling means coupled to said overload responsive means and to said valve means and operable by said overload responsive means to disable said valve means after a switch opening and reclosing operation to effect delayed operation of said resetting means if overload current reappears in said system, said overload responsive means being ineffective to operate said disabling means if overload current does not reappear in said system.

13. A repeating circuit interrupter having switch means in circuit with the system being protected, switch opening means including overload responsive means coupled to said system, switch closing means operable after a switch opening operation, hydraulic integrating means coupled to said overload responsive means and operable from an initial position to initiate time delayed opening of said switch means after a first predetermined number of switch opening operations and to prevent the reclosure of said switch means after a second predetermined number of operations, biasing means normally effective after a time delay to reset said hydraulic integrating means to its initial position, and valve means having a valve element coupled to said overload responsive means and port means connected to said hydraulic integrating means, said valve element being movable into a position to close said port means upon the appearance of overload current in said system, means biasing said valve element away from port means to effect more rapid operation of said hydraulic integrating means if overload current does not reappear in said system after the appearance and disappearance thereof.

14. A repeating circuit interrupter including switch means in circuit with the system being protected, switch opening means including overcurrent'responsive means coupled to said circuit, switch closing means operable after a switch opening operation, normally inactive time delay means for delaying the opening of said switch means, lockout means adapted to be rendered effective for preventing the closure of said switch means, a hydraulic cylinder, an integrating piston disposed in said cylinder, said piston having a normal position adjacent one end of said cylinder, means operable by said overcurrent responsive means to advance said piston an incremental distance toward the other end of said cylinder upon each occurrence of overcurrent in said system, said piston being effective to initiate the operation of said time delay means upon being moved a first distance toward the other end of said cylinder and said lockout upon being moved a second predetermined distance, resetting means normally effective after a time delay to return said piston to its normal position, valve means normally operable to initiate rapid resetting of said piston, and disabling means coupled to said overcurrent responsive means and to said valve means and operable by said overcurrent responsive means to disable said valve means after a switch opening and reclosing operation to effect delayed operation of said resetting means if overcurrent reappears in said system, said overcurrent responsive means ineffec tive to operate said disabling means if ovenload current does not reappear in said system.

15. A repeating circuit interrupter including switch means in circuit with the system being protected, switch opening means including overcurrent responsive means coupled to said circuit, switch closing means operable after a switch opening operation, normally inactive time delay means .for delaying the opening of said switch means, lockout means adapted to be rendered effective for preventing the closure of said switch means, a hydraulic cylinder, an integrating piston disposed in said cylinder, said piston being biased toward one end of said cylinder, means operable by said overcurrent responsive means to advance said piston an incremental distance toward the other end of said cylinder upon each occurrence of overcurrent in said'system, said piston being effective to ini tiate the operation of said time delay means upon being moved a first distance toward the other end of said cylinder and said lockout means upon being moved a second predetermined distance, the biasing of said piston being effective after a time delay to return said piston to the one end of said cylinder, and valve means coupled to said overcurrent responsive means and to said cylinder and normally operable after a switch opening and reclosing operation to vent said cylinder and effect the more rapid resetting of said piston, said overcurrent responsive means being operable upon the reappearance of overcurrent in said system after a switch opening and re closing operation to prevent the operation of said valve means.

16. A repeating circuit interrupter including switch means in circuit with the system being protected, switch opening means including overcurrent responsive means coupled to said circuit, switch closing means operable after a switch opening operation, normally active time delay means for delaying the opening of said switch means, lockout means adapted to be rendered effective for preventing tht closure of said switch means, a hydraulic cylinder, an integrating piston disposed in said cylinder, said piston being biased toward one end of said cylinder, pump means operable by said overourrent responsive means for delivering a measured quantity of hydraulic fluid to the one end of said cylinder to advance said piston an incremental distance toward the other end of said cylinder upon each occurrence of overcurrent in said system, said piston being effective to initiate the operation of said time delay means upon being moved a first distance toward'the other end of said cylinder and said lockout upon being moved a second predetermined distance, the biasing of said piston being effective after a time delay to return said piston to the one end of said cylinder, and dump valve means having a valve element coupled to said overcurrent responsive means and port means connected to said cylinder, said valve element beingmovable into a position to close said port means upon the appearance of overcurrent in said system, means biasing said valve element away from port means to efiect more rapid resetting of said piston after a switchopening and reclosing operation if overcurrent does not reappear in said system.

References Cited by the Examiner UNITED STATES PATENTS 2,891,121 6/1959 Date 20089 BERNARD A. GILHEANY, Primary Examiner.

R. N. ENVALL, JR., Assistant Examin

Claims

2. AN AUTOMATIC PROTECTIVE DEVICE INCLUDING SWITCH MEANS IN CIRCUIT WITH THE SYSEM BEING PROTECTED, ABNORMAL CONDITION RESPONSIVE MEANS COUPLED TO SAID SYSTEM, LOCKOUT MEANS OPERABLE TO EFFECT A CONTINUOUS SWITCH OPEN CONDITION, INTEGRATING MEANS COUPLED TO SAID ABNORMAL CONDITION RESPONSIVE MEANS AND OPERABLE AFTER A PREDETERMINED NUMBER OF APPEARANCES AND DISAPPEARANCES OF AN ABNORMAL CONDITION TO RENDER SAID LOCKOUT MEANS EFFECTIVE, RESET MEANS FOR RESETTING SAID INTEGRATING MEANS, DELAYING MEANS OPERABLE TO DELAY THE RESETTING OF SAID INTEGRATING MEANS BY SAID RESET MEANS, AND MEANS COUPLED TO SAID ABNORMAL CONDITION RESPECTIVE MEANS AND TO SAID INTEGRATING MEANS AND OPERABLE TO RENDER SAID DELAYING MEANS INOPERATIVE TO DELAY SAID RESETTING MEANS TO EFFECT RAPID RESETTING OF SAID INTEGRATION MEANS IF SAID ABNORMAL CONDITION DOES NOT REAPPEAR IN SAID SYSTEM AFTER THE APPEARANCE AND DISAPPEARANCE THEREOF.