US2846621A

US2846621A - Closing mechanism for an electric circuit breaker

Info

Publication number: US2846621A
Application number: US610736A
Authority: US
Inventors: Thellwell R Coggeshall; Ugo R Tognella
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1956-09-19
Filing date: 1956-09-19
Publication date: 1958-08-05
Anticipated expiration: 1975-08-05

Description

Aug. 5, 1958 T. R. COGGESHALL ETAL 2,846,621

CLOSING MECHANISM FOR AN ELECTRIC CIRCUIT BREAKER Filed Sept. 19, 1956 3 Sheets-Sheet l Inventors: Th el 1 we I I P. Co ggesh al I,

Ugo R. T021": e l I a by W Th ei rthorn e9.

Aug. 5, 1958 T. R. COGGESHALL ET AL 2 CLOSING MECHANISM FOR AN ELECTRIC CIRCUIT BREAKER Filed Sept. 19, 1956 3 Sheets-Sheet 2 Inventors:

Thelivvell F2. Goggeshall,

Ugo -R'l o gfiella,

Attorney.

1958 T. R. COGGESHALL ETAL 2,846,621

CLOSING MECHANISM FOR AN ELECTRIC CIRCUIT BREAKER Filed Sept. 19, 1956 3 Sheets-Sheet 3 Inventors: TheHweH R.Coggeshall Ugo FlTognHa,

The I -rttoP'r-v e H United States Patent CLOSING MECHANISM FOR AN ELECTRIC CIRCUIT BREAKER Thellwell R. Coggeshall, Cynwyd, and Ugo R. Tognella,

Philadelphia, Pa., assignors to General Electric Company,.a corporation of New York Application September 19, 1956, No. 610,736 7 Claims. (Cl. 317-54) This invention relates to a closing mechanism for an electric circuit breaker and, more particularly, to a control arrangement for controlling the operation of such a mechanism.

As a general rule, if a circuit breaker is closed on a fault and automatically trips open in response to the presence of the fault, it is most important that it remain open and not repeatedly attempt to close. As is well known. such repeated reclosing operations, commonly termed pumping, can lead to serious damage both to the breaker and the system, especially if allowed to continue.

Numerous control schemes heretofore have been devised "for preventing such pumping action, but, most frequently, they have been complicated and expensive and have involved the use of a number of costly multiplecontact relays.

Accordingly, an object of our invention is to provide for a circuit breaker a simple and inexpensive control scheme which operates to prevent circuit breaker pumping.

Another object is to provide an anti-pump control scheme which does not require the use of expensive relays.

Another object is to construct the control scheme in such a manner that it can utilize a small, inexpensive and non-continuously-rated electromagnetic device for initiating circuit breaker operation.

In carrying out our invention in one form, we provide an electric circuit breaker which has motive means operable to produce closing of the breaker. This motive means is controlled by the action of an electromagnetic device having a driving part operable from a neutral to an operated position- This movement of the driving part is transmitted to a control linkage which responds thereto by causing the motive means to operate to produce cir' cut breaker closing. The control linkage is so constructed that it is inelfective to again cause a breaker closing operation so long as said driving part is held in its operated position. The driving part is moved into its operated position by closing a selectively-operable switch in an ene'rgizingcircuit for the electromagnetic device. This also results in a seal-in circuit being established for the electromagnetic device, and this seal-in circuit holds the driving part in its operated position. The seal-in circuit is maintained so long as the selectively-operable switch is held closed, and, as a result, further closing operations of the circuit breaker are precluded so long as the switch is held closed.

For a better understanding of our invention, reference may be had to the accompanying drawings taken in connection with the following specification, wherein:

Fig. 1 is a perspective view illustrating one form of circuit-breaker closing mechanism embodying our invention. The mechanism is shown in the breaker-open position.

Fig. 2 is a wiring diagram schematically illustrating a control circuit for the mechanism of Fig. 1. The various components of the control circuit are shown in the position which they would occupy when the mechanism is in the position of Fig. 1.

Patented Aug. 5, 1958 "ice Fig. 3 is a cross-sectional view illustrating certain details of the closing mechanism.

Fig. 4 is an exploded schematic view illustrating the mechanism and its control circuit upon the completion of a closing operation.

Fig. 5 is a wiring diagram illustrating a modified form of our invention.

Fig. 6 schematically illustrates another modified form of our invention.

Referring now'to Fig. l, the circuit breaker shown therein comprises a reciprocable contact-actuating rod, or switch member 8, which is biased to the open-circuit position shown by means of a suitable opening spring 9. For transmitting closing thrust to the actuating rod 8, there is provided aconventional trip-free linkage L which comprises a pair of

toggle links

10 and 12 pivotally joined together at a knee 14. One of the toggle links 12 is pivotally connected at its opposite end to a bell-crank 15, which, in turn, is pivotally connected to the reciprocable contact-actuating rod 8. The other toggle link 10 is connected by a pivot pin 18-tothe upper end of a guide link 19'. This guide link 19 is pivotally supported at its lower end on a fixed fulcrum 20. Thepivot pin 18 carries a latch roller 21 which cooperates with a suitable trip latch 22, which is arranged to be operated in response to predetermined circuit conditions by means of a suitable conventional tripping solenoid 23. So long as the trip latch remains in the latched position shown in Fig. 1, the

toggle

10, 12 is capable of transmitting thrust to the movable contact-actuating rod 8. Thus, when the knee 14 is lifted from the position shown in Fig. 1, the

toggle

10, 12 is extended and drives the contact-actuating rod 8 to the left toward closed position against the bias of opening spring 9.

This lifting of the knee 14 is accomplished by the action of a rotatable cam 24 cooperating with the usual roller 25 which is mounted at the knee 14. When the cam 24 is rotated clockwise through a complete revolution by means soon to be described, it moves from the position of Fig. l to the position of Fig. 4 and lifts the knee 14,

. thereby extending the

toggle

10, 12 and closing the breaker. Fig. 4 shows this toggle portion of the breaker mechanism in closed position, where it is held by the force of the cam acting through the knee 14 to maintain the

toggle

10, 12 extended.

Should the trip latch 22 (Fig. 1) be tripped when the breaker is closed, or even during the closing stroke, the

toggle

10, 12 will be rendered inoperative to transmit closing thrust to the contact-actuating rod 8. As a result, the opening spring 9 will be free to drive the contactactuating rod 8 to its open-circuit position. A suitable resetting spring 27 cooperates with the guide link 19 to reset the mechanism L to the latched position (shown in Fig. 1) after it has been tripped.

For rotating the cam 24 to drive the circuit breaker closed, there is provided a stored-energy closing device which comprises a torsion spring 30 suitably coupled at one end to the cam 24. As shown in Fig. 1, this coupling comprises a disc 31 attached to the cam shaft 32 and carrying a pin 34 to which the forward end of the spring is suitably anchored. The rear end of the spring is anchored by a suitable pin 34a to a rotatable sprocket 35.

Charging of the spring 30 is accomplished by rotating the sprocket 35 in a clockwise direction by means of a suitable charging motor 36 coupled to the sprocket 35 by means of a conventional chain drive 37. The manner in which this charging motor is controlled will appear more clearly hereinafter. Unwinding of the spring 30 at its rear end by possible back-tracking of the sprocket 35 is prevented by means of a suitable holding pawl 38.

For controlling the rotation of the cam 24, there is provided a latch or closing release prop 40 which cooperates with an abutment such as the roller 41 suitably secured to the cam 24. This prop 40 is keyed to an actuating shaft 42 which is journaled within a U-shaped bracket 43. The prop is biased into its holding position shown in Fig. 1 by means of a prop-resetting spring 44 surrounding the shaft 42. When the prop 40 is released, i. e., moved clockwise out of the path of the abutment 41, the main spring 30-is free to drive the cam 24 clockwise at high speed from the breaker-open position of Fig. l. The prop 40 is reset to its holding position immediately and in ample time to arrest the movement of the cam 24 after it has rotated through a complete revolution to drive the breaker into the closed position shown in Fig. 4.

For releasing the prop 40 to produce the above-described breakerclosing action, a releasing device 50 is provided. This releasing device 50 is claimed in application Serial No. 612,007, now Patent No. 2,820,119, Miller et al., filed September 25, 1956, and assigned to the assignee of the present invention, and reference may be had to that application for a complete description of its details and advantages.

The following brief description of the releasing device 50 is believed to be adequate to convey an understanding of the present invention. Referring to Fig. 1, the releasing device comprises a guide link 51 mounted for pivotal movement about a fixed pivot 52 and carrying at its lower end a transversely-extending actuating pin 53. Pivotally mounted on this pin 53 is an actuating pawl 54, which has a transversely projecting portion 55 contacting the rear side of the guide link 51. The projecting portion 55 is releasably held in this position by a spring 57 which allows the pawl to rotate counterclockwise about the pin 53 of Fig. 1 under certain conditions, which will soon be described. The actuating pawl 54 cooperates with a pin 59 carried by a crank 60 secured to the prop actuating shaft 42. When the actuating pin 53 is moved in a counterclockwise direction about its pivot 52 from the position of Fig. l, the actuating pawl, with its lower surface 54a acting through the crankpin 59, rotates the crank 60 in a clockwise direction and thereby releases the prop 40. The lower surface 54a of the actuating pawl is so shaped that as soon as it effects this releasing action, it moves free of the crankpin 59 and permits the crank 60 to be returned to its original position by means of the prop resetting spring 44. This, of course, results in the prop being immediately reset in time to arrest the movement of the main cam 24 after it had been spring driven through a complete revolution to effect breakerclosing. The parts of the releasing device would occupy the position shown in Fig. 4 immediately after the prop had been released and had reset.

This prop-releasing action ,of the pawl 54 is produced by means of a slidable, suitably-guided L-shaped operating rod 62 which is coupled to the actuating pin 53 by means of a connecting link 63. This connecting link 63 at one end is pivotally mounted on the actuating pin 53 and at its other end has a slot 64 which receives the outer leg of the operating rod. A compression spring 65 acting through the operating rod 62 maintains the parts of the releasing device in the normal or neutral position of Fig. 1 against the opposing bias of a weaker tension spring 66, which tends to move the actuating pin 53 counterclockwise about its pivot 52.

For actuating the operating rod 62, a solenoid 67 having its armature, or driving part, 67a secured to the outer end of the operating rod 62 is provided. When this solenoid 67 is sufficiently energized, it acts, with the aid of spring 66, to move the operating rod 62 through its normal stroke to the right from the neutral position of Fig. 1. This motion is transmitted through the connecting link 63 to move the actuating pin 53 counterclockwise about its pivot 52. This drives the pawl surface 54a into engagement with the crankpin 59 and produces the propreleasing action described above. After release, the prop 40 immediately resets, as described above, and the parts of the releasing device 50 are then in the position of Fig. 4. When the operating rod 62 is thereafter released, the releasing device 50 resets under the influence of its spring 65, and the parts thereof are restored to their position of Fig. 1. During prop-releasing action, the pawl 54 acts against the pin 59 in an essentially unyielding manner due to engagement between the projection 55 and the guide link 51 as the actuating pin 53 moves counterclockwise. When the device is reset from Fig. 4, however, the pawl yields when it engages the crankpin 59, since the crankpin is then on an opposite side of the pawl. This yielding action continues until near the end of the resetting stroke, at which time the pawl has been dragged clear of the crankpin 59 and is free to reset under a the influence of its own spring 57.

It should be apparent from Fig. 4 taken in connection with the above description that the releasing device 50 is incapable of again releasing the prop 40 so long as its driving part, the armature 67a, is held in the position of Fig. 4 inasmuch as the crankpin 59 is then behind the pawl 54. To again release the prop 40, it is necessary to first reset the releasing device 50 along with its driving part 67a at least partially to the position of Fig. l, as described in the preceding paragraph.

For controlling the charging motor 36 and for ensuring against operation of the releasing device 50 before the motor 36 has charged the spring 30 to a safe energy level, a controlling arrangement 70 has been provided. This controlling arrangement is claimed in application S. N. 611,331, Miller et al., and its details form no part of the present invention. It is "believed, however, that a brief description of its construction and operation would facilitate an understanding of the present invention. Referring to Fig. 3, this controlling arrangement 70 comprises a nut or nut-like member 72, which preferably is formed as a tubular sleeve having a screw 72:: projecting radially into its bore. As shown in Fig. 3, the nut is coupled to the breaker-operating cam 24 by means of a calibrating rod 73, coaxial with the tubular cam shaft 32, and pinned at 74 and 75 to the nut 72 and the cam shaft 32, respectively. Meshing with the nut 72 is a threaded controlling rod 76 which is coupled to the spring-charging sprocket 35 for rotation therewith but is free to move axially with respect to the sprocket. The coupling between the sprocket 35 and the threaded member 76 comprises a crank 77 shown welded to the threaded member 76 and carrying at its outer end a crankpin 78 which is slidably received in a boss 79 carried by the sprocket.

Referring to Fig. 3, if the sprocket 35 together with the threaded controlling member 76 is rotated in a springcharging direction, then the nut 72 will act to shift the threaded controlling member axially outward. Conversely, if the breaker operating-cam 24 is thereafter released, its rotation will cause nut 72 to return the controlling member 76 axially inward to the position shown in Fig. 3. The manner in which this axial movement of the controlling member 76 is utilized will soon appear more clearly.

As will "be apparent from Fig. 3, the threaded controlling member 76 has a tubular outer end which is slidably supported on the inner end of the sprocket shaft 26. A push rod 85.is loosely mounted in the coaxial bores of the tubular shaft 25 and the tubular controlling member 76. Cooperating with the push rod and formingan additional part of the controlling arrangement 70 is a T-shaped switch-actuating lever 88. As shown in Fig. 3, this actuating lever 88 is pivotally mounted on the stationary framework 27 by means of a pivot 89 and is biased in a counterclockwise direction by a torsion spring 90. For reasons which will soon appear, this lever 88 serves to actuate a pair of switches 92 and 94 in response to appropriate'axial movement of the push rod 85.

As shown in Fig. 4, the switch 92 is a normally biasedv closed switch which is connected in series with the charging motor 36 across a suitable current source 95. The switch 94, on the other hand, is a normally biased-open switch which is connected across the current'source in series with the coil of solenoid 67 and with a manuallyoperable switch 96. Because of their respective functions, the switch 92 is hereinafter termed the motor-controlling switch and the switch 94 is termed the releasing-device controlling switch.

As shown in Figs. 2 and 4, the releasing-device controlling switch 94 is shunted by means of an impedance in the form of a resistor 105. This resistor 105 is of such a size that when the control switch 94 is open, the resistor allows sufficient current to flow through the coil of solenoid 67 to maintain its armature 67a sealed-in should the armature then be in its operated position of Fig. 4. Thus, so long as an operator holds the switch 96 closed, the releasing device 50 remains in the position of Fig. 4 in spite of opening of the control switch 94 during spring-discharge. As long as the releasing device 50 is held in this position of Fig. 4 and is not permitted to reset, it is incapable of reinitiating another operation of the stored-energy device 30-35, as previously described.

The resistor 105 is also of such a size that, should the control switch 94 be open, the resistor limits the current flowing through the coil of solenoid 67 to a value which is insufiicient to cause pick-up of the solenoid armature, i. e., movement from its normal-deenergized position of Fig. 1 to its operated position of Fig. 4. As a result, if the solenoid armature 67a is in its normal deenergized position of Fig. 1 and the control switch 94 is then in its open position, closing of the switch 96 will be ineffective to produce solenoid operation.

Operation of the control arrangement 70 is as follows. Assume first that the main spring 30 has been discharged and the operating mechanism has just moved into the position of Figs. 3 and 4. The normally-closed motor switch 92 would then be closed and the motor would be driving sprocket 35 in such a direction that the threaded controlling member 76 would be moving axially outwardly due to its meshing engagement with the nut 72. This axially-outward movement of the controlling member 76 is transmitted through the push rod 85 to the switch actuating lever 88 and acts to open the motor-controlling switch 92 when the spring has been charged to a predetermined safe energy level. This motor cut-otf terminates the charging operation, except for a slight amount of overtravel, after which the parts occupy the neutral position of Fig. 1.

As shown in Fig. 4, during the time that the main spring 30 was in the above-described discharged condition, the releasing-device control switch 94 was open and, thus, the manually-operable switch 96 was rendered inefiective to produce energization of the closing-release coil 67. Accordingly, electric operation of the releasing device 50 was prevented during this interval, and thus the danger of premature release of the main spring 30 was obviated. The releasing-device control switch 94 is so adjusted that just prior to motor cut-off during a springcharging operation, it is closed by the action of the switch-actuating lever 88. As a result, when the parts have been motor-driven from position of Fig. 3 into the position of Fig. 1, as described in the preceding paragraph, the releasing-device control switch 94 is closed and no longer acts to disable the manually-operable switch 96. With the control switch 94 closed (assuming the switch 107 also to be closed), the manually-operable switch 96 can be selectively operated to again release the mainv spring 30 and close the breaker if it is then open.

When the releasing device 50 is operated to permit the main spring 30 to discharge, the resultant rotation of the nut 72 quickly withdraws the controlling member 76 from its extended position of Fig. 1. This allows the torsion spring 90 to drive the control-switch actuating lever 88 together withthe push rod 85 into the position 6 shown in Figs. 3 and 4. This closes the motor control switch 92 and thereby initiates a spring-charging operation of the typedescribed above.

In order to prevent attempted closure of a circuit breaker whenever it is already closed, it is customary to provide the breaker with a b switch connected in series with the breakers closure-initiating device. Such switches are customarily actuated by the circuit breakers operating mechanism and are open when the breaker is closed and closed when the breaker is open. We have shown such a b switch in Figs. 1, 2 and 4 at 107. As can be seen in Figs. 2 and 4, this b switch 107 is connected in series with both the manually-operable switch 96 and the coil of the closing-release solenoid 67 and in parallel with the seal-in resistor 105.

When the circuit breaker is in the open position illustrated by Fig. 2, the manually-operable switch 96 can be closed to energize and operate the closing-release solenoid 67 thereby producing breaker closing. When, however, the breaker is in a closed position with its b switch 107 open, the manually-operable switch 96 is ineffective to produce operation of the solenoid 67. This is the case because with the b" switch 107 open, the seal-in resistor limits the current through the solenoid coil to a value which is insufiicient to cause pick-up of the solenoid. Thus, with the breaker closed, the b switch 107 prevents operation of the solenoid 67 and thereby prevents attempted closure of the breaker, as is desired.

The seal-in resistor 105 cooperates with the closingrelease device 50 to prevent circuit-breaker pumping in the following manner. Assume that the breaker is open with the various control switches in the position of Fig. 2 and that the operator closes switch 96 and holds it closed for a protracted period. The closing release solenoid 67 would be operated to produce breaker closing, thereby opening the b switch 107 and the control switch 94. This would divert current through the seal-in resistor 105, which, in turn, would allow sufficient current to flow through the coil of solenoid 67 to maintain its armature 67a sealed-in, as shown in Fig. 4. Since the releasing device 50 cannot reset so long as the armature of the solenoid 67 is sealed-in and since the releasing device 50 is inoperative to produce another closingoperation until reset, it will be apparent that so long as the manually-operable switch 96 is held closed, the releasing device will be incapable of initiating another closing operation. Thus, if the breaker should be closed on a fault and should automatically trip open in response thereto while the operator was still holding the switch 96 closed, there would be no repeated closure even though the b switch 107 reclosed in response to reopening of the breaker. In other words, pumping would be effectively prevented.

The importance of resistor 105 will be apparent when the operation of the control scheme is considered without the resistor. For example, Without the resistor 105, when the control switch 94 and the b switch 107 would be open in response to breaker-closing, they would deenergize the solenoid 67 and allow the closing release device 50 to reset even though the operator was holding the switch 96 closed. If the breaker then opened in response to a fault and the operator was sitll holding the switch 96 closed, the b.switch 107 followed by the control switch 94 would close to produce energization and operation of the solenoid 67, thus producing the repeated closing operations, or pumping, which our invention avoids.

Fig. 5 illustrates a slightly modified form of our invention which permits us to use a small non-continuously rated solenoid for producing the desired operation of the releasing device 50. This modified form of our invention difiers from that of Figs. l-4 only in its inclusion of a normally-closed switch 110 connected in parallel with the seal-in resistor 105 and operated 7 to open position by the solenoid armature 67a near the end of its operating stroke. This switch 110 serves to prevent continuous full-voltage energization of the solenoid 67 under those conditions in which the operator fails to promptly open the' manually-operable switch 96 after the breaker has closed and then tripped open. Under such conditions, the solenoid armature 67a would remain sealed-in, as described in connection with Figs. 1-4, and the switches 94 and 107 would be closed. Without the switch 110, the resistor 105 would be shorted out and full control voltage would then be applied to the solenoid coil; but with the switch 110, which is then open, the resistor 105 is effectively maintained in series with the solenoid coil, thus desirably limiting the voltage and current to which the coil is subjected. Thus, since the solenoid is subjected to full-voltage only during the short interval required for operating it from its neutral to its operated position, we are able to utilize an intermittantly-rated solenoid smaller than would otherwise be possible. Thus, the switch 110 enables us to utilize the seal-in resistor 105 not only to prevent circuit breaker pumping but also as a means for protecting the solenoid from prolonged overcurrent.

Although we have illustrated our invention in connection with a stored-energy type of closing mechanism, it is to be understood that its application is not limited to such mechanisms. For example, Fig. 6 shows an electric motor-driven mechanism utilizing certain features of our invention. For convenience, those parts of Fig. 6 which correspond to similar parts in Figs. 1-4 have been given corresponding reference numerals.

Referring to Fig. 6, the rotatable cam 24 when driven clockwise by the electric motor 112 lifts the roller 25 to extend the

toggle

10, 12 and drive the switch member 8 toward closed position. When the cam 24 has been driven through approximately a complete revolution from the position of Fig. 6, the breaker will be fully closed.

The motor 112 is arranged to be energized from a suitable current source 114, 115 upon closure of a normallyopen control switch 117, which is connected in series with the motor. As will soon appear more clearly, the switch 117 acts only to initiate motor operation inasmuch as it is closed for only a short interval. Thereafter, a seal-in switch 120 connected in parallel with the control switch 117 acts to continue operation of the motor when the control switch 117 is opened. This switch 120, which is controlled by an auxiliary cam 121 connected to the rotatable shaft of main cam 24, is closed in response to initial motor operation and is opened near the end of a complete revolution of the main cam 24 to terminate motor operation.

For initiating a closing operation, a device 50 corresponding to the closing release device 50 of Figs. l-4 is utilized. This device 50 comprises a solenoid 67 which can be operated when the breaker is in the open position of Fig. 6 by closing the manually-operable switch 96. This completes an energizing circuit extending through the switch 96, the b switch 107, and the coil of the solenoid 67. The solenoid responds by moving the actuating pawl 54 to the right into driving engagement with the crankpin 59. This pivots the crank 60 clockwise about its pivot 42 causing the crank to close'the switch 117. When the solenoid stroke has been completed, the parts of the initiating device 50 are in a position corresponding to that of Fig. 4. That is, the pawl 54 has been moved free of-the crankpin 59, permitting the spring 44 to return the crank 60 back to its original position thereby causing the switch 117 to be opened.

This momentary closing of the control switch 117, which results from a full stroke of the solenoid 67, is suificient to cause the motor 112 to drive the cam 24 through a complete revolution in the manner previouslydescribed, thereby producing a breaker-closing operation.

When the breaker closes, the b switch 107 is opened and control current is thereby diverted through the sealin resistor connected in shunt with the b switch 107. This maintains the solenoid sealed-in, holding the parts of the initiating device 50 in a position corresponding to that of Fig. 4. In this position, the initiating device is incapable of actuating the crank 60 to initiate another closing operation. As previously pointed out, it is necessary to reset the initiating device 50 at least partially to the position of Fig. 6 before it is again capable of actuating the crank 60 to effect another breaker-closing operation.

Thus, if the breaker, after closing as above-described, trips open in response to a fault or the like and the operator is still holding the manually-operable switch 96 closed, no additional closing operations would be initiated inasmuch as the initiating device 50 would then be held in its sealed-in inoperative position corresponding to that shown in Fig. 4. Thus, circuit breaker pumping would be prevented in the modification of Fig. 6 in essentially the same manner as in that of Figs. l-4.

Although our invention has been illustrated only in connection with the operation-initiating device 50, it is to be understood that it is applicable to other forms of operation-initiating devices, such as, for example, those shown in our application S. N. 512,638, filed June 2, 1955,. now Patent No. 2,769,874. All of these devices are characterized by their ability to initiate operation of a closing mechanism in response to movement of a driving part from a neutral to an operated position and by their incapability of initiating another closing operation so long as the driving part is held in its operated position.

While we have shown and described a particular embodiment of our invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the invention in its broader aspects and we, therefore, intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of our invention.

What we claim as new and .desire to secure by Letters Patent of the United States is:

1. In an electric circuit breaker, motive means operable to produce closing of the breaker, electromagnetic means having a driving part operable from a neutral to an operated position, control means responsive to movement of said driving part from said neutral to said operated position for causing said motive means to operate to produce circuit breaker closing, said control means being ineffective to again cause a breaker-closing operation of said motive means until said driving part is returned at least partially to its neutral position, a selectively-operable first switch connected in series-circuit relationship with said electromagnetic means and closable to produce operation of said electromagnetic means, a second switch connected in series-circuit relationship with said electromagnetic means and with said first switch, switch-actuating means responsive to the operative position of said breaker for closing said second switch when the breaker isopen and for opening said second switch when the breaker is closed, said switch actuating means acting to hold said second switch open so long as the breaker is closed, and means etfective when said breaker is closed for maintaining said electromagnetic means sufliciently energized to hold said driving part in said operated position in the event that said first switch is held closed during the time said second switch is open, said switch-actuating means acting to close said second switch in response to those breakeropening operations which occur even while said first switch is being held closed.

2. In an electric circuit breaker, motive means operable to produce closing of the breaker, electromagnetic means having a driving part operable from a neutral to an operated position, control means responsive to movement of said driving part from said neutral to said operated position for causing said motive means to operate to produce circuit-breaker closing, said control means being inetfective to again cause a breaker-closing operation of said motive means until said driving part is returned at least partially to its neutral position, a selectively-operable first switch connected in series-circuit relationship with said electromagnetic means, a second switch connected in series-circuit relationship with said electromagnetic means and with said first switch, means for closing said second switch when the breaker is open and for opening said second switch when the breaker is closed, impedance means connected in shunt relationship with said second switch and in series relationship with said first switch to provide a seal-in circuit effective when said breaker is closed for maintaining the driving part of said electromagnetic means in its operated position in the event that said first switch is held closed during the time said second switch is open.

3. The combination of claim 2 in which said impedance means when connected in current-limiting series relationship with said electromagnetic means acts to limit the current through said electromagnetic means to a value which is insufiicient to produce operation of said driving part out of its neutral position.

4. In an electric circuit breaker, motive means operable to produce closing of the breaker, electromagnetic means having a driving part operable from a neutral to an operated position, control means responsive to movement of said driving part from said neutral to said operated position for causing said motive means to operate to produce circuit breaker closing, said control means being ineffective to again cause a breaker-closing operation of said motive means until said driving part is returned at least partially to its neutral position, a selectively-operable first switch connected in series-circuit relationship with said electromagnetic means, a second switch connected in series-circuit relationship with said .electromagnetic means and with said first switch, means for closing said second switch when the breaker is open, and for opening said second switch when the breaker is closed, impedance means connected in shunt relationship with said second switch and in series relationship with said first switch and said electromagnetic means to provide a seal-in circuit effective when said breaker is closed for maintaining the driving part of said electromagnetic means in its operated position in the event that said first switch is held closed during the time said second switch is open, a third switch connected in series with said second switch and in shunt with said impedance means, and means for closing said third switch whenever said driving part is in its neutral position and for opening said third switch whenever said driving part is in its operated position whereby to maintain said impedance means connected in current-limiting series relationship with said electromagnetic means whenever said driving part is in its operated position.

5. In an electric circuit breaker, motive means operable to produce closing of the breaker, electromagnetic means having a driving part operable from a neutral to an operated position, control means responsive to movement of said driving part from said neutral to said operated position for causing said motive means to operate to produce circuit-breaker closing, said control means being inelfective to again cause a breaker-closing operation of said motive means until said driving part is returned at least partially to its neutral position, a selectively-operable first switch connected in series-circuit 10 relationship with said electromagnetic means, a second switch connected in series-circuit relationship with said electromagnetic means and with said first switch, means for closing said second switch when the breaker is open and for opening said second switch when the breaker is closed, impedance means connected in shunt relationship with said second switch and in series relationship with said first switch and said electromagnetic means to provide a seal-in circuit effective when said breaker is closed for maintaining the driving part of said electromagnetic means in its operated position in the event that said first switch is held closed during the time said second switch is open, and means for maintaining said impedance means connected in current-limiting series relationship with said electromagnetic means whenever said driving part is in its operated position.

6. In an electric circuit breaker, motive means operable to produce closing of the breaker, electromagnetic means having a driving part operable from a neutral to an operated position, control means responsive to movement of said driving part from said neutral to said operated position for causing said motive means to operate to produce circuit-breaker closing, said control means being ineffective to again cause a breaker-closing operation of said motive means until said driving part is returned at least partially to its neutral position, a selectively-operable first switch connected in series-circuit relationship with said electromagnetic means, a second switch connected in series circuit relationship with said electromagnetic means and with said first switch, means for operating said second switch from closed to open position in response to initiation of a breaker-closing operation, and means comprising a seal-in circuit shunting said second switch and effective when said breaker is closed for maintaining said driving part in said operated position in the event that said first switch is held closed during the time said second switch is open.

7. In an electric circuit breaker, motive means operable to produce closing of the breaker, electromagnetic means having a driving part operable-from a neutral to an operated position, control means responsive to movement of said driving part from said neutral to said operated position for causing said motive means to operate to produce circuit-breaker closing, said control means being ineffective to again cause a breaker-closing operation of said motive means so long as said driving part is held in its operated position, a selectively-operable first switch connected in series-circuit relationship with said electromagnetic means, a second switch connected in series-circuit relationship with said electromagnetic means and with said first switch, means for operating said second switch from closed to open position in response to initiation of a breaker-closing operation, and means comprising aseal-in circuit shunting said second switch and effective even while said breaker is closed for maintaining said driving part in said operated position in the event that said first switch is held closed during the time said second switch is open.

References Cited in the file of this patent UNITED STATES PATENTS