US2488601A - Sectionalizing circuit breaker - Google Patents

Description

,V 22p i949 c. E. Mmmm ET AL SECTIONLIZING CIRCUIT BREAKER (5 Sheets-Sheet Filed May 8, 1948 Nm 22p c. E. MQSLEY ET AL.

SECTIONALIZING CIRCUIT BREAKER 3 Sheets-Sheet 2 Filed May 8, 1948 Nov. 22, 1949 c. E. MOSLEY ET Ar. 2,4889693?.

SECTIONALIZING CIRCUIT BREAKER Filed May 8, 1948 3 SheetswSneet 3 Patented Nov. 22, 1949 SECTIONALIZING CIRCUIT BREAKER Carl E. Mosley, Overland, Mo., and Kenneth R. Brown, Des Moines, Iowa, assignors to W. N. Matthews Corporation, St. Louis, Mo., a corporation of Missouri Application May 8, 1948, Serial No. 25,924

(Cl. ZOO-108) 8 Claims. l

This invention relates to circuit breakers, and more particularly to sectionalizing circuit breakers for isolating a permanently faulted branch line of a power distribution system from the remainder of the system.

Among the several objects of the invention may be noted the provision of an automatic sectionalizing circuit breaker for use in a branch line of a power distribution system and in association with an automatic circuit recloser in the main line of the system for isolating the branch line from the main line upon the occurrence of a fault of substantial duration in the branch line; the provision of a circuit breaker of the class described adapted automatically to lock out and permanently to open the branch line in response to a sustained overload condition caused by a permanent fault in the branch line, but to remain closed upon the occurrence of momentary overload conditions caused by temporary faults in the branch line; the provision of a current-relay-controlled circuit breaker of this class adapted for trouble-free operation even though subject to extreme overloads; and the provision of a circuit breaker such as described which is economical to manufacture and reliable in operation in exposed locations. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplied in the structures hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. l is a View in side elevation of a circuit breaker of this invention shown in solid lines in closed-circuit position;

Fig. 2 is a fragmentary plan view showing a control mechanism of the circuit breaker;

Fig. 3 is an enlarged vertical section taken substantially on line 3-3 of Fig. 2;

Fig. 4 is an enlarged vertical section taken substantially on line 4-4 of Fig. 2;

Fig. 5 is a vertical section taken on line 5-5 of Fig. 3, parts being broken away; and,

Fig. 6 is a schematic wiring diagram.

Similar reference characters indicate correspending parts throughout the several views of the drawings.

Referring to the drawings, particularly to Fig. 1, the circuit breaker of this invention, generally designated I, comprises a mounting base or arm 3 adapted to be bolted in vertical position upon a cross arm or any other suitable support. Arm 3 is a conductor so as to be connectible to neutral or ground. Insulators 5 and I extend horizontally from the upper and lower ends of the arm 3, respectively. The upper insulator 5 is clamped at one end in a split ring clamp 9 carried by the upper end of the mounting arm 3. The lower insulator I isclamped at one end in a split ring clamp I I carried by the lower end of the mounting arm 3.

The upper half I3 of the upper clamp 9 carries a grounding electrode I5. Supported by a clamp II around the middle Waist portion of the insulator 5 is an intermediate electrode I9. At the outer end of the upper insulator 5 is a split ring clamp v2l, the upper half of which supports a third electrode 25. The electrodes I5, I9 and 25 form in series two surge gaps for lightning arresting purposes. They ground transient highvoltage surges of current due to lightning or the like. The surge current is carried off through the mounting arm 3 to ground.

Similarly, the lower half I0 of the lower clamp II carries a grounding electrode 2l. Supported by a clamp 23 around the middle waist portion of the lower insulator I is an intermediate electrode 3|. At the outer end of the lower insulator 'I is a split ring clamp 33, the lower half 35 of which supports a third electrode 31. The electrodes v2'I, 3i and 3l form in series two surge gaps for lightning arresting purposes. They ground transient high-voltage surges of current due to lightning or the like, the surge current being carriedA oi through clamp II to ground. The lower half I0 of the clamp II is provided with a terminal 39 for connection of a ground wire.

, The split ring clamp 2l at the outer end of the upper insulator 5 comprises upper and lower jaws 4I and 43, respectively, held in clamping relation around the outer end of the upper insulator 5 by means of clamping bolts 45. The electrode 25 is xed in the upper jaw 4I. The lower jaw 43 is formed with extensions 41 in one of which is a feed line wire connector 49 (Fig. 2) The lower jaw 43 is formed with a horizontal bracket 5I having a bifurcated end portion 53. A platform 55 of insulating material is fixed upon bracket 5I by means of screws 51 and 59 extending through the platform into the legs of the bifurcated end portion 53 of the bracket. The lower jawA 43 (including bracket 5I) is an elec- 3 trical conductor for conduction of current from connector 49.

'Ihe clamp 33 at the outer end of the lower insulator 1 comprises the lower jaw 35 which carries electrode 31 and upper jaw 6|. These jaws are held in clamping relation around the outer end of the lower insulator by means of bolts 63. The lower jaw 35 of the clamp, which is an electrical conductor has an extension 65 for a line wire connector 61. The upper jaw 6| of clamp 33 is formed with a pair of spaced lugs 69 1`or the pivotal mounting of a movable switch member generally designated 1|. The latter comprises a hinge member 13 pivoted at 15 between the lugs 69. A switch bar 11 extends upward from hinge member 13. The switch bar is encased in an insulating tube 19, composed of a suitable material such as fiber. This makes it safe il' inadvertently touched. Hinge member 'I3 is provided with a hook 8| for application of a linemans stick for switch reclosing purposes. A pig-tail shunt from hinge member '|3 around the pivot to the upper jaw 6| of clamp 33 is shown at B3. A coil spring 05 biases switch member 1| toward the mounting arm 3 to its open-circuit position. At the upper end of switch bar 11 is a generally U-shaped terminal 01 for cooperation with a latch member 09 carried by the platform 55.

The switch bar 11 is latched in circuit-closing position by latch member 89, the latter having below the platform a hooked portion 9| engageable in notch 83 in the U-shaped terminal 81 to hold the switch bar 11 in vertical position against the bias ol' spring 85. When latch member 89 is actuated to release the switch bar, the latter swings toward mounting arm 3 under the bias oi` spring 85 until its terminal 81 engages a lug 95 struck out from the mounting arm 3, as illustrated in dotted lines in Fig. 1. Latch member B9 is pivoted at 91 in a U-shaped bracket 99 mounted on the bottom of platform 55. The latch member is generally of L-shape, having an arm extending upwardly from the hooked portion 9| through a slot |03 in platform 55.

A catch |05, pivoted at |01 at the upper end of a bracket |09 mounted upon the platform 55, cooperates with the upper end of the latch arm |0| to hold the latch member 89 in position to lock switch bar 11 in its vertical closed-circuit position (Fig. 4). Catch |05 has a notch on one side of its pivot |01 for receiving the upper end of latch arm |0|. The latch member 89 is biased to its released position wherein its hooked portion is raised out of notch 93 in switch bar terminal 81 by means of a spring ||3 compressed between a portion ll5 of bracket |09 and latch arm |0|. The catch |05 is biased toward its position for holding engagement of the upper end of latch arm |0| in notch (clockwise as viewed in Fig. 4) by means of a spring ||1. A link ||9 is pivotally connected to the catch |05 on the side opposite the notch for rocking the catch to release the latch arm |0|. Link ||9 is adapted to be pulled down to rock the catch |05 to release latch arm |0| by a step-bystep overload-responsive mechanism generally designated mounted upon platform 55.

As illustrated, the overload-responsive mechanism |23 comprises a current relay or solenoid |2| having a frame |23, a coil |25 and an armature or plunger |21 slidable within the coil. The frame |23 is mounted upon the platform 55 with the coil |25 in horizontal position for horizontal movement of the plunger |21. The vplunger extends out of the end of the coil toward the upper insulator 5 and carries at its outer end a shifter fork |29. Fork |29 engages the vertical arm of a bell crank lever 13| fixed on a rock shaft |33. Shaft |33 is journalled in a bearing lug |35 bent up from an electrically conductive plate |31 xed on platform 55, and in the vertical legs |39 and |4| of a bracket |43 of inverted U-shape xed upon the plate |31 (Fig. 3). A tension spring |45 is connected between the end of the horizontal arm of bell crank lever |3| and a lug |41 extending from the frame |23 of solenoid |2| to bias the bell crank counterclockwise as viewed in Fig. 4 to pull the solenoid plunger |21 out from coil |25. Spring |45 is shown completely in Figs. 1 and 3 but fragmentarily in Fig. 4. Outward movement of solenoid plunger |21 under the bias of spring |45 is limited by pin |49 extending upward from platform 55 (Figs. 2 and 3). The arrangement is such that when the coil |25 is energized by an overload current, plunger |21 is retracted into the coil, and shifter fork |29 at the outer end of plunger |21 rocks the vertical arm of bell crank lever |3| toward the solenoid, at the same time tensioning spring |45 so that it may act to pull the plunger out of the coil when the coil is subsequently deenergized.

A pawl arm |5| is rotary on rock shaft |33 next to the vertical arm of bell crank lever I3|. The pawl arm is biased in the direction toward the solenoid by a tension spring |53 connected between the upper end of the pawl arm and a lug extending from the solenoid frame |23. A finger |51 extends horizontally from the vertical arm of the bell crank lever |3| for engagement by the pawl arm |51 to control movement of the latter. Finger |51 extends through a notch |59 in pawl arm |5| adjacent its upper end in that side of the pawl arm toward the solenoid. The arrangement is such that ringer |51 normally holds pawl arm |5| in a retracted position determined by engagement of the pawl arm with a stop |6| against the bias of spring |53 (Figs. 1 and 4). When the vertical arm of bell crank lever |3| is rocked toward the solenoid upon energization of coil |25, pawl arm |5| is released and rocks toward the solenoid under the tension of spring |53. Stop 16| is conveniently constituted by a finger bent up from the material of plate |31. A pawl |63 is pivoted at |65 on pawl arm |5| for driving an indexing ratchet |61 forward upon rocking of pawl arm |5| in the direction toward the solenoid. A pawl spring |69 biases the pawl |63 toward ratchet |61.

Ratchet |51 is mounted upon a ratchet shaft 11| journalled at one end in a bearing lug bent up from plate |31 and at its other end in an extension |13 of leg |33 of bracket |43. Fixed on ratchet shaft |1| adjacent extension |13 is a holding ratchet |15. A holding pawl |11 is pivoted at |19 for engagement with holding ratchet |15. Pivot |19 is in a bearing lug |00 struck up from a stampingr l0| fixed to the top of bracket |43. Stamping |8| is L-shaped in plan (Fig. 2), having a transverse arm |83 extending toward pawl arm |5| fo11 engagement by a depending finger |85 of pawl |63 when the pawl arm is in its retracted position to raise the pawl. Stamping IBI has a longitudinal arm |81 from which the bearing lug |30 extends upward, and is provided at the end of longitudinal arm |81 with a portion |89 bent upward and then transversely to provide a stop for limiting upward movement of holding pawl |11 (Fig. 5). The latter is biased toward engagement with holdingratchet |15 by .a .spring |9|.

A portion of the plate |31is bent up as indicated at |93 to provide a mounting for a dashpot type ,timer |95. Other types of timers may be used. The time |95 shown comprises a cylinder |91 having Va cio-sed end fixed to the upper end of mounting |93, the cylinder extending horizontally toward the upper insulator r5. A piston rod |93 extends from a piston 29| in cylinder |91 out ofthe open end of the cylinder for engagement by a dashpot operating arm 293 xed at its lower end on rock shaft |33. The piston 29| and piston rod |99 are biased toward the operating arm 2.93 by a compression spring 205 reacting from the closed end cylinder |91 against the piston.

The cylinder Y|91 is provided with a checkvalve 201 adapted freeiy to permit escape of air from Within cylinder |91 when piston 29| -is moved toward the closed end of the cylinder, and to checkflovv of air into the cylinder Without entirely preventing such .o-w, when the piston is moved toward operating arm 293 by spring 205 to retard the return movement of piston 23| and piston rod |99 under the bias of spring 295. On piston rod |199 is a collar 299 for engaging a iinger `2|| extending upward from holding pawl |11 near the end Yof the return stroke of the piston. The arrangement is such that as piston `rod |99 nears the end of its return stroke, collar 269 engages nger'2ll to rock holding pawl |11 out of engagement with holding ratchet |15.

Ratchet shaft |1| has an arm 2 i3 iixed thereon for actuating the catch-operating link |9 through Y a lost-motion connection (Figs. 4 and 5). As illustrated, this connection is conveniently provided by means of a screw 2| 5 at the outer end of the arm 2! 3 extending through an elongate slot 2|1 in the link I9. A tension spring 2|9 is connected between the arm 2|3 and a finger. 22| bent from the material of bracket |43 for biasing the shaft |1| to rock arm 2|3 upward.

Screws. 51 and 59 by means of which the platform 55 is attached to bracket 5| are insulated from plate |31, the latter being suitably recessed and apertured for this purpose. Screw 51 is connected by a wire 223 to one terminal of vsolenoid coil |25. The other terminal of the coil is con- :nected by a wire 225 to conductive plate |31 at 221.

Plate |31 is in electrically conductive relation with respect to bracket |09, which is .made of conductive material. Bracket |99 has lower flanges 2:29 fixed to platform 55 by screws 23|. These screws extend through the platform and hold bracket 99 on the bottom of the platform. They provide for electrical connection from plate |31 through bracket |99 to bracket 99.

A contact member 233 is pivoted at 91 to bracket 99. This contact member is formed with a contact pad portion235 for engagement by the terminal 81 on the upper end of switch bar11 when the latter is in its circuit-closing position. When the switch bar is in this position, it holds the contact member 233 against the bias of a compression spring 231 reacting from the end of recess 239 in the bottom of platform 55 against an extension 24| of contact member 233. Con- .tact member 233 carries a pair of spring contacts 243 for engagement with the legs of the biiurcated end portion 53 oi bracket 5| when switch bar 11 is in circuit-opening'position. A pigtail A245 connectsbracket. 9,9 and contact member 233. A'llfthe parts above platformil are enclosed iby a protective-cover ,241.

The .circuit breaker .of this invention is par.- ticularly adapted for use ina branch line of a power distribution system in connection with a main or so-called back-up automatic circuit recloser in the .main line of the system for isolating the branch line from the remainder of the system upon occurrence of a permanent fault in 4the branch line, but not upon occurrence of a .temporary fault of short duration in the branch line. For this purpose, circuit breakers are connected in the branch lines of a power distribution system as illustrated'in Fig. 6. Main line L leads from substation S of the power distribution system and includes aback-up automatic circuit recloser CR of a usual type. Branch lines B lead from main line L and each includes a circuit breaker of this invention Each branch line B leads to line wire connector 49 and from line Wire rconnector 91 of the circuit breaker (Figs. l and 2).

The automatic circuit recloser CR, as known, is adapted automatically to operate through a predetermined number of cycles in response to occurence of a fault anywhere in the system, in each of which cycles it opens and recloses the main line L. If the fault has not been corrected by the time the recloser has operated through the predetermined number of cycles, the recloser locks out to open the main line until it is manually reclosed. Such reclosers are well known in this art and need no detailed description.

Each circuit breaker l is adapted automatically to disconnect its branch line B from the main line L upon occurrence of a fault in the branch line if the fault has not cleared by the time the recloser has operated through a number of cycles less than the number required to lock out the recloser. As herein illustrated, the circuit breaker l is adapted to lock out so as to disconnect the branch line after the third reclosure of recloser CR if the fault in the branch line has not cleared by-that time, and the recloser is adapted automatically to reclose at least one more time before locking out, so that the main line is closed after the faulted branch line is isolated from the main line. This maintains vservice upon theremainder of the system. Each of ratchets |61 and |11 accordingly has (for example) three teeth for threestep operation of the circuit breaker as will be made clear. Other numbers of teeth may be used, provided the number of operations to lock out a branch circuit breaker CB is one less than the operations required to lock out the main circuit recloser CR.

Operation is as follows:

Under normal operating conditions, theswitch bar 11 is latched in circuit-closing position by engagement of the hooked portion 9| lof the latch member 89 4in notch 93 in terminal 81 at the upper end of the switch bar (Fig. 1). The terminal 31 engages the contact pad 235 of contact member 233 and holds contact member 233 against the bias of spring 231 in a position wherein spring contacts 243 are disengaged from the legs of the bifurcated end portion 53 of bracket 5|. The branch line circuit is completed through the circuit breaker from the connector 49 through clamp jaw 43 and bracket 5|, screw 51, wire 223, solenoid coil |25, Wire 225, connection 221, plate |31, bracket |09, screws 23|, bracket 99, pigtail 24,5, contact member 233, terminal 81, switch bar 11, hinge member 13, pigtail 83, and clamp 33 to the line wire connector 61.

The latch hook 9| is retained in latching position in notch 93 in terminal 81 of the switch bar by the engagement of the upper end of latch arm in notch I I I of the catch |05. While line current is flowing through the solenoid coil |35, energization of the solenoid for normal current values is insufficient to draw the solenoid plunger |21 into the coil. Consequently, bell crank lever I3I, pawl arm |5|, and dashpot operating arm 203 are in their illustrated retracted positions. Rocker arm 2 I3 is in its uppermost position wherein the screw 2|5 at its outer end extends through the upper end of the elongate slot 2 I1 in the catch-operating link ||9 (Fig. 5). Piston rod |99 of the dashpot timer is fully extended by the spring 205 in dashpot cylinder |91.

Assuming that a permanent fault occurs in the branch line B in which the circuit breaker I is connected, both branch line B and main line L are overloaded. The resultant overload current in line B energizes solenoid coil |25 sufficiently to attract plunger |21 into the coil. Overload current in main line L causes circuit recloser CR to open the main line L. The recloser, however, does not open the main line until shortly after the solenoid plunger has been attracted into the solenoid coil.

When the solenoid plunger |21 is attracted into the coil, shifter fork |29 at the outer end of the plunger rocks the vertical arm of bell crank lever I 3| toward the solenoid. This releases the pawl arm for rocking movement toward the solenoid under the tension of its biasing spring |53. As the pawl arm rocks toward the solenoid, pawl |63 on the pawl arm rocks into engagement with ratchet |61 and indexes this ratchet forward for a distance of one tooth. Since holding ratchet |15 is fixed on ratchet shaft |1| along with ratchet |61, it is also indexed forward for a distance of one tooth. Meanwhile, bell crank lever |3| has rocked the rock shaft |33 to pivot dashpot operating arm 203 toward the dashpot to drive piston rod |99 into the dashpot cylinder |91. The collar 209 thereupon moves away from linger 2|| of holding pawl |11, so that pawl |11 rocks into engagement with holding ratchet |15 behind the first tooth thereon to prevent reverse rotation of ratchet |15, ratchet shaft |1| and ratchet |61. Rotation of the ratchets through one tooth rocks the rocker arm 2 I 3 on the ratchet shaft |`|I downward, but not far enough downward to operate the catcheoperating link I |9, due to the lost motion provided for by slot 2|1.

After the above-described operations have occurred, the solenoid plunger |21 is pull-ed away from the coil |25 by spring |45 acting through bell crank lever I3I and the shifter fork |29, the plunger moving to its normal retracted position against stop pin |49. This occurs upon deenergization of solenoid coil |25 upon opening of the main line L by circuit recloser CR. As the vertical arm of bell crank lever |3I returns to its retracted position, finger |51 thereon pulls pawl arm |5| back to its retracted position thereby tensioning pawl arm spring |53. Ratchets |51 and |11 remain in the position to which they have been advanced by pawl |53, however, due to the holding' action of pawl |11 on holding ratchet |15. When the bell crank lever |3| rocks to its retracted position, it rocks the rock shaft !33 to pivot dashpot operating arm 203 back to its retracted position to permit the spring 205 to drive the piston rod vI 99 out of the dashpot cylinder |91. Return movement of piston rod |99, however, occurs more slowly, due to the slow rate of return Cil of air into the dashpot cylinder through check valve 201. Consequently, the collar 209 on piston rod |99 delays engagement with finger 2|| of holding pawl |11 to release the holding pawl (for example, the delay is of the order of ten seconds).

The recloser CR immediately recloses the main line L. Since the fault in branch line B is a per marient fault, overload current again flows through the branch line and energizes solenoid I2I suiiiciently to attract plunger |21 into the coil. Pawl arm |5| is thereupon actuated in the same manner as above described to cause pawl |63 to index ratchet |61 forward through a second step. Holding pawl |11 engages behind the second tooth of holding ratchet |15 to hold both ratchets in advanced position. Rotation of the ratchets through this further step rotates ratchet shaft |1| to rock arm 2|3 further downward, but still not far enough to actuate the catch-operat ing link ||9. Piston rod |99 meanwhile is slowly moving out of dashpot cylinder |91, but has not moved far enough for collar 209 to engage linger 2|| on the holding pawl |11 to release the latter.

rFhe circuit recloser CR then opens for the second time, since the fault in branch B has not been cleared. This opens the main line and deenergizes solenoid coil |25. Bell crank lever I3I, pawl arm |5|, and dashpot operating arm 2|3 thereupon return to their retracted positions for the second time.

The circuit recloser CR then again recloses the main line L. Since the fault in branch line B has still not cleared, overload current again ilows through the solenoid coil |25. This pulls in the solenoid plunger |21 to rock bell crank lever I3| and release the pawl arm |5| for movement toward the solenoid so that pawl |63 engages the ratchet |01 and drives it forward through a third step. This rocks the arm 2 I 3 on ratchet shaft I1i suliiciently for screw 2|5 to engage the lower end of slot 2|1 and pull down the catch-operating link |I9. This raises the notched end of catch |05 to release the upper end of latch arm |0|. Latch member B9 is thereupon biased by springr ||3 to its released position wherein its hooked portion 9| is raised out of notch 93 in switch bar terminal 81. This releases the switch bar 11, which swings downward about pivot 15 under the bias of spring 05 until terminal 81 at the upper end of the switch bar engages lug 95. Upon such movement of the switch bar, contact member 233 is released and pivots about pvot 91 under the bias of spring 231 until spring contacts 243 engage the legs of the bifurcated end portion 53 of bracket 5|.

With switch bar 11 in its open-circuit position, the branch line D is isolated from lthe main line L. The circuit recloser CR, however, automatically recloses once more to close the main line L to maintain service on the remainder of the power distribution system Ultimately, piston rod |99 of the dashpot timer moves to its fully ex tended position, and collar 209 thereon engages finger 2|I of holding pawl I 11 to rock the pawl |11 out of engagement with holding ratchet |15. This releases both ratchets, the ratchet shaft |1| and the arm 2|3 on the ratchet shaft for return to their initial positions under the bias of spring 2I9. Pawl |63, at this time, is held in raised position above ratchet |61 by engagement of fin ger of pawl |63 with arm |83, to permit this return movement.

Assuming that the parts are in their initial illustrated positions and that a temporary fault, of momentary duration, occurs in the branch line 9 B, both the branchline and the main line L are momentarily overloaded. The overloadl current energizes the solenoid coil |25y sufliclently to attract plunger |21 into` the coil. This causes the ratchets |61 and |15" to be stepped forward through one tooth and held in this position by the' holding pawl |11 in the manner above defi scribed. Rocker arm 2l3 rotates downward, but

not far enough to operate the catch-operatingv link IIS. The dashpot operating arm 203 drives' the piston rod |99 intorthe dashpot cylinder |91.Y

The solenoid coil |25 is subsequently deenergized when main line L is opened by circuit recloser CR. This permits all the parts to return to their initial positions. Since the fault was' of momentary duration, and has now cleared, the solenoid coil is not re-energized sufliciently to attract the plunger, and recloser CRv remains closed to complete both the main line L and the' branch line B. Piston rod |99 moves slowlyv out of the dashpot cylinder |91 and ultimately the collar 209 on the rod engages nger 2|| of the holding pawl |11 and rocks it away' from the holding ratchet |15. to permit spring 2|9 to return the ratchets |61 and |15 and the rocker' arm 2 |3 to their initial retracted positions. This resets the step-by-step pawl and ratchet indexing mechanism for three-step operation for a subsequent permanent fault.

It will be understood that the temporary fault in the branch line may be of such duration as to cause operation of the pawl and ratchet indexing mechanism through two' steps without releasing the switch bar 11. Under such circumstances, theA solenoid operates twice, and the ratchet mechanism isstepped forward through two teeth, but as long as the fault is cleared before the circuit breaker has had time to operate through the third step, the bar 11 remains in circuitclosing position. The circuit breaker locks out to open the branchline only for faults of such duration as to give the circuit breaker time to' operate through three steps, as determined by the speed of the opening and reclosing operations of the back-up circuit recloser CR. As stated above, the number of steps may be varied simply by varying the number of teeth on the ratchets and the extent of lost motion at 2|5-2I1. The check valve 201 of the dashpot timer |95 is adjusted so that the collar 209 on the dashpot piston rod will not trip linger 2|| to release holding pawl |11 until the circuit breaker has had time to operate through the desired number of steps. To reclose the circuit breaker once it has locked out, it is merely necessary for the lineman to pull down on the hook 8| with a linemans stick to swing switch bar 11 upward into latched position. This swings latch member 89 so that the upper end of its latch arm catches in the notch in the catch |05.

It will be observed that as soon as the switch bar 11 moves to open-circuit position, spring contacts 243 move into engagement with the legs of the bifurcated end portion 53 of bracket 5|. If an arc should be drawn from the contact pad 235 to the terminal 81 of the switch bar, the resultant heavy arcing current will be shunted from the solenoid coil, flowing from bracket through spring contacts 243 to contact pad 235, rather than through screw 51 and wire 223 to the coil. Thus, heavy arcing current is prevented from damaging the coil. If such an arc is sustained, the line becomes grounded or connected to neutral through the arc when terminal 31 engages grounding lug 95. A flexible ber shield 249 may be provided on the clamp 33, as illustrated in Fig. 1 to prevent flash-over.

An important advantage of the above-described circuit breaker is that the force acting to move the pawl arm |5| and the pawl |63 thereon, to actuate ratchets |61 and |15, is independent of the overload current actuating the solenoid. This is because the bell crank lever |3| actuated by the solenoid functions merely as a detent for holding the pawl arm |5| in retracted position,

and is not mechanically coupled to the arm. When the solenoid is energized by overload current and its plunger rocks the bell crank'toward the solenoid, the bell crank releases the pawl arm so that the latter is rocked only by its spring |53 for indexingpurposes. The force with which pawl a-rm |5I, ratchets |61 and |15, ratchet shaft |1|, rocker arm 2|3, link ||9 and catch |05 are actuated depends only upon the bias of spring |53, and notupon the force with which plunger |21 of the solenoid is attracted into the coil |25. Thus, these parts are not affected by the jolt on the bell crank lever' |3| when the plunger is attracted into the coil with great force and rapidity by a high overload current, and may be made of relatively small size without being subject to breaking down. At the same time full force of the solenoid action is applied to setting the timing mechanism |95. This is desirable because most of such mechanisms require substantial driving force for setting them. Equivalent timing mechanism might be a spring-biased bellows, an escapement-controlled gear train or the like.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from' the scope of the invention, it is intended that all matter conta-ined in the above description or shown in the'accompanying drawings shall be interpreted asillustrative andl not in a limiting sense.

We claim:

l; A circuit breaker comprising a switch having a movable switch member biased to open-circuit position, ay latch for latching the switch member in closed-circuit position against its bias, a current relay operable in response to flow of overload currentY in the circuit in which the switch is connected, a resettabie indexing pawl and ratchet mechanism actuated by said relay and controlling said' latch through a' linkagek including a .lostmotion" connection to release the latch after a predetermined number of cycles of operation of the relay, said mechanism including a holding pawl for holding it in indexed postion, a timedelay mechanism for releasing the ho'dng pawl to reset the indexing mechanism a predetermined time interval after an initial cycle of operation of the relay, and an operating member controlled by the relay for initiating the operation of the time-delay mechanism.

2. A circuit breaker comprising a switch having a movable switch member biased to open-circuit position, a latch for latching the switch member in closed circuit position against its bias, a catch for releasably holding the latch in latching position, an indexing mechanism operable through a predetermined number of steps for releasing the catch, a movable actuating member for the ,indexing mechanism and biased to actuate the indexing mechanism, a current relay operable in response to ilow of overload current in the circuit in which the switch is connected, and a de- 11 tent controlled by the relay for holding said actuating member in a retracted position against its bias, said detent releasing said actuating member upon operation of the relay for movement of the actuating member under its bias to actuate the indexing mechanism through one step.

3. A circuit breaker as set forth in claim 2 wherein the indexing mechanism is biased to an initial position, and further including a releasable holding member for holding the indexing mechanism in its stepped positions, time control mechanism for releasing said holding member a predetermined time interval after an initial operation of the relay, and an operating member controlled by the relay for initiating the operation of the time control mechanism.

4. A circuit breaker comprising a switch having a movable switch member biased to opencircuit position, a latch for latching the switch member in closed-circuit position against its bias, a catch for releasably holding the latch in latching position, a ratchet mechanism biased to an initial position, a linkage including a lost-motion connection between said ratchet mechanism and catch for releasing the catch upon rotation of the ratchet mechanism from its initial position through a predetermined number of steps, a driving pawl for the ratchet mechanism, a current relay operable in response to flow of overload current in the circuit in `which the switch is connected, mechanism controlled by the relay to actuate the driving pawl to drive the ratchet mechanism forward through one step upon each operation of the relay, a holding pawl for holding the ratchet mechanism in its stepped positions against its bias, and time-delay mechanism for releasing said holding pawl a predetermined time interval after an initial cycle of operation of the relay to permit return of said ratchet mechanism to its initial position under its bias.

5. A circuit breaker comprising a switch having a movable switch member biased to opencircuit position, a latch for latching the switch member in closed-circuit position against its bias, a resettable step-by-step indexing pawl and ratchet mechanism controlling said latch through a linkage including a lost-motion connection to release the latch upon operation of the indexing mechanism through a predetermined number of steps, said mechanism including a driving pawl normally biased to a retracted position and a holding pawl for holding it in indexed position, a solenoid operable in response to flow of overload current in the circuit in which the switch is connected controlling said driving pawl to release it to operate the indexing mechanism through one step upon each operation of the relay, and timedelay mechanism for releasing the holding pawl to reset the indexing mechanism a predetermined time interval after an initial cycle of operation of the relay.

6. A circuit breaker comprising a switch having a movable switch member biased to open-circuit position, a latch for latching the switch member in closed-circuit position against its bias, a catch for releasably holding the latch in latching position, a ratchet mechanism biased to an initial position, a linkage including a lost-motion connection between said ratchet mechanism and catch for releasing the catch upon rotation of the ratchet mechanism from its initial position through a predetermined number of steps, a rock shaft, a pawl arm rotary on the rock shaft carrying a driving pawl for the ratchet mechanism, a rst spring biasing the pawl arm toward the ratchet mechanism for driving the latter through the driving pawl, a detent xed on the rock shaft for holding the pawl arm in retracted position against the bias of the spring7 a second spring coupled to the rock shaft for biasing said detent to position to hold the pawl arm in retracted position, a solenoid coupled to the detent and operable in response to flow of overload current in the circuit in which the switch is connected against the bias of said second spring to actuate the detent to release the pawl arm to drive the ratchet mechanism through one step, and a holding pawl for holding the ratchet mechanism in its stepped positions against the bias of said ratchet mechanism.

7. A circuit breaker as set forth in claim 6, further including a time-delay mechanism for releasing the holding pawl a predetermined time interval after an initial cycle of operation of the solenoid to permit return of the ratchet mechanism to its initial position under its bias, and an operating arm for the time-delay mechanism iixed on said rock shaft.

8. A circuit breaker as set forth in claim '7 wherein the time-delay mechanism comprises a dashpot having a cylinder and piston, a piston rod extending from the cylinder for engagement by the operating arm, and a member on the piston rod for engaging and releasing thc holding pawl.

CARL E. MOSLEY. KENNETH R. BROWN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,982,986 Garlington Dec. 4, 1934 2,387,372 Watkins Oct. 23, 1945 2,452,233 Gerard Oct. 26, 1948

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