US2549350A - Circuit interrupter - Google Patents

Description

April 17, 1951 J. M. WALLACE ET AL CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Fig.2

Filed Sept. 14, 1944 Fig. 3.

d n MM 0 c 2 M a a N l. R V Z 0 m n M n MJ 5 B e 2 MW J April 17, 1951 J. M. WALLACE ETAL CIRCUIT INTERRUPTER 2 Sheets-Sheet 2 Filed Sept. 14, 1944 WITNESSES:

' INVENTORS James M. Wallace and Weldon L. Mezi.

Patented Apr. 17, 1951 UNITED STATES PATENT OFFlCE CIRCUIT INTERRUP'IER James M. Wallace, Braddock, and Weldon L.

Metz, Willrinsburg', Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 14, 1944, Serial No. 553,996

9 Claims. 1

This invention relates generally to electric circuit interrupters, and more specifically to circuit breakers of the automatic reclosing type.

In circuit interrupters of the type having electroresponsive means for separating the interrupter contacts which are biased into engagement in order to automatically reclose the circuit when the opening means is deenergized, a rapid pumping action of the contacts is encountered under conditions where the electrical condition to which the contact separating means responds is relatively low in value. Under such conditions, the interrupter contacts separate, but before they can separate any appreciable distance, interruption occurs thus deenergizing the contact separating means and. the contacts immediately reclose. Although interruptcrs of this type are generally provided with means for delaying reclosing of the contacts, the time delay means is usually arranged to be ineffective just prior to actual engagement of the contacts in order to permit a relatively rapid final movement of the contacts into engagement. This means that such time delay means are ineiiective to prevent rapid contact pumping under the conditions stated above, and even integrating means usually provided for preventing more than a predetermined number of closely successive operations generally require appreciable contact separation to be effective, so that such means may fail to operate under conditions of very small contact separation. therefore obvious that if such electrical conditions persist, a rapid pumping action of the contacts also persists, resulting in excessive arcing at the contacts, and no opportunity is given for the condition to clear. Such a pumping action of the contacts may continue until the interrupter eventually destroys itself.

One method of solvin this problem by alteration of the contact actuating mechanism is disclosed in the copending application of J. M. Wallace and A. W. Ogg, Circuit Interrupters, Serial No. 40,958, filed July 27, 1948, as a continuation of their abandoned application Serial No. 540,192,.

filed June 14, 1944, both of which are assigned to the same assignee of this invention.

One object of this invention is to prevent pumping of the contacts of an automatic reclosing circuit interrupter of the type described, by providing for the first time in association therewith, a contact structure which will insure contact separation at least a predetermined distance on each circuit interrupting operation.

Another object of this invention is to provide in an automatic reclosing interrupter of the type It is 2 described, novel means for insuring time delay in reclosing the interrupter contacts, irrespective of the current or voltage interrupted.

Another object of this invention is to prevent pumping in an automatic reclosing circuit interrupter of the type described by the provision of a relatively stationary contact structure which will insure at least a predetermined amount of con tact separation on each circuit interrupting operation.

Another object of this invention is to provide in an automatic reclosing interrupter of the type described, a novel contact arrangement which is capable of providing at least a predetermined amount of contact separation on each circuit interrupting operation, at a rate which is independent of the rate of movement of the electroresponsive contact separating means.

These and other objects of this invention will become more apparent upon consideration of the following detailed description of a preferred embodiment thereof, when taken in connection with the attached drawing, in which:

Figure 1 is a substantially central longitudinal section view of a circuit interrupter embodying this invention;

Fig. 2 is an enlarged view of a portion of the interrupter shown in Fig. l, with the parts at a different position;

Fig. 3 is a view like Fig. 2, but illustrating the parts at still another position.

Fig. 4 is a substantially central longitudinal sec tion view of a modified form of circuit interrupter embodying this invention; and

Fig. 5 is a substantially central longitudinal section view through the outer casing of the circuit interrupter shown in Fig. 4, but taken substantially at right-angles to the section of Fig. 4, and illustrating the mechanism in elevation with one supporting plate removed to better illustrate the parts.

This invention is illustrated in Figs. 1 to 3 of the drawings as being embodied in a circuit breaker of the general type described in J. M. Wallace Patent No. 2,333,604, issued November 2. 1943, to the same assignee as this invention. Since most of the parts of the circuit breaker illustrated are identical with corresponding parts of the circuit breaker disclosed in the Wallace patent, reference is hereby made to this patent for a more detailed description of the construction and operation of such parts. In general, the circuit breaker illustrated is mounted in a tubular casing 2 of any desired insulating material, preferably a weatherproof insulating material, such as porcelain or the like. Casing 2 has a closed bottom apertured to receive a terminal bolt 4 adapted to be secured in position and to secure a line conductor 8 thereto by nuts 6.

A supporting bracket 5 may be secured about a mid-portion of easing 2, with packing material "I interposed therebetween. The top of casing 2 is open, and is adapted to be covered by a cover casting l having a terminal fixture H thereon, for receiving another line conductor. An anchor ring 9 is secured on casing 2, as by cast metal l3, and casting [0 may be secured to ring 9 in any desired manner (not shown). Cover casting ID has a hollow portion I 2 to which access may be had by a threaded filler plug [5, and in which a shaft [4 is journaledl The shaft l4 extends transversely of the cover casting, and rotatably supports a generally U-shaped spring support it, the leg portions of which are rotatably mounted on shaft 54. A spring 22 is coiled about the shaft, and reacts on spring support [6 and the cover casting, to bias the spring support in a counterclockwise direction. Spring support it, however, is normally prevented from rotating counterclockwise under the influence of spring 22, by toggle links l8 and 2G pivotally mounted on the spring support and cover ID as by a pivot pin I9, and by a shaft 2|, respectively, and normally maintained at an overcenter position by engagement of a handle 14 rigid on shaft 2|, with a stop screw 18 mounted beneath a hood portion '52 integral with the cover casting. A reclosing spring 24 is also coiled about shaft I4, and reacts between spring support [6 and an actuating lever 26, to normally bias lever 26 in a clockwise direc tion, for a purpose to be described. Actuating lever 26 is connected by links 28 of insulating material, to a contact rod 30 which extends down through casing 2 into a tubular arc chamber 32.

Are chamber 32 is preferably of an insulating material, such for example as fiber or the like, and is provided with caps 34 and 36 threadedly mounted on opposite ends thereof. Contact rod 3c is provided with a sleeve of insulating material 38 on the portion thereof which passes through an opening in cap 34 of the arc chamber. Cap 36 of the arc chamber is electrically connected with terminal bolt 4 by means of a coil compression spring 40 of a resilient electrical conducting material, such for example as a copper alloy, which engages between cap 3% and the enlarged head 42 of bolt 4.

A solenoid coil 44 is provided about contact rod 30 adjacent the upper end thereof. Contact rod 30 has an actuating sleeve 45 slidably mounted thereon within solenoid coil 44, and this actuating sleeve is provided with a flange 43 at the upper end thereof for engagement with a shoulder on contact rod 30, for actuating the contact rod. Dash-pot cylinder 52, in the form of a sleeve of insulating material, is positioned within solenoid coil 44, and a tubular core 55 for the coil is slidably mounted between dashpot sleeve 52 and actuating sleeve 46.

At the top of solenoid coil 44 there is mounted integrating means for counting closely succeeding circuit interrupting operations, and this means comprises a pawl 54 which is generally of U-shape, having one leg seated on top of the supporting frame for coil 44 and slotted so as to overlie flange 48 of actuating sleeve 45, and so as to be raised each time a circuit interrupting operation occurs. A coil compression spring 5B is provided on a pawl guide 51 for returning the pawl to the position shown, and a notched piston 58 is provided in a cylinder sleeve 60 adjacent the pawl, and the piston is accessible through an opening in sleeve 60 provided adjacent the upper leg of pawl 54, so as to be engaged thereby when the pawl is raised,

Solenoid coil 44 is connected in series with the circuit through the interrupter, and this circuit may be traced from one terminal I I through cover casting l0 and a conductor 62 to one of the taps 64 of coil 44, by way of a conductor 66 to actuating rod 30, and thence to a stationary contact structure (to be described), cap 36, spring 40, to terminal bolt 4 and line conductor 8. When currents above a predetermined value are present in the circuit sufiicient to energize coil 44 enough to attract core 50 upwardly, initial upward movement of the core occurs without any movement of contact rod 30. After movement of core 5!] sufficient to engage the lower end of actuating sleeve 46, this sleeve is then moved upwardly, thereby carrying pawl 54 upwardly and notched piston 58 along with it, until flange 48 on the actuating sleeve engages shoulder 5| on contact rod 30, to finally move the contact rod upwardly to disengage the stationary contact structure and interrupt the circuit. Upward movement of contact rod 30 results in stressin reclosing spring 24, so that when the circuit is interrupted this spring acts automatically to move contact rod 30 back downwardly to reclose the circuit.

Reclosing movement of contact rod 30 is delayed, however, by a wedge-type latch plate 61 pivotally mounted on the contact rod as at 69. A latch rod 13 is received in an aperture provided in latch plate 51, so as to cooperate with the latch plate to latch the contact rod at whatever position it is moved in opening the circuit due to the wedging action of plate 61, under the influence of a coil compression spring II. It will be observed that latch plate 61 is effective to latch the contact rod at all positions, except positions closely adjacent the closed circuit position illustrated in Fig. l, where latch rod 13 is provided with a reduced section 15, too small to be wedged by the aperture in latch plate 6?. Accordingly, after the circuit is opened, contact rod 30 is held latched at the position to which it has been moved during the circuit interrupting operation, even though it is biased closed by reclosing spring 24. Latch plate 6! can be released only by return movement of core 50, which is necessarily slow because of the dashpot action thereof between dashpot sleeve 52 and actuating sleeve 46. This dashpot action is also effective to delay opening of the contacts after energization of solenoid coil 44 sufficient to attract core 50 upwardly. Solenoid core 50 thus constitutes a dashpot piston which is eifective to delay opening of the circuit, and also to delay reclosing.

On certain overload conditions, such for example as very small overloads, or on operation of the breaker on low voltages where interruption of the circuit occurs substantially as soon as the breaker contacts separate, the travel of contact rod 30 may be insufiicient to cause engagement of latch plate 61 on the large section of latch rod 13, and may even be insufiicient to move pawl 54 upwardly any substantial amount. This means that reclosing spring 24 is effective to immediately reclose the circuit, and if the electrical condition which caused opening still exists, the breaker willagain operate to separate its contacts substantially the same amount with no time delay this time, because solenoid core 50 has not had time to return to its normal position shown in Fig. l, and therefore, so long as this electrical condition persists, the breaker will operate with a rapid pumping action. This is extremely undesirable, because if the electrical condition does not clear in a short time, excessive arcing occurs at the breaker contacts, and the breaker may eventually destroy itself.

On heavier overloads, the breaker operates as described above with a time delay both on opening and on closing the breaker contacts for each circuit interrupting operation. If such heavier overloads are transient in nature, this time delay permits them to clear before the circuit is reclosed. In this event, notched piston 58 slowly returns to its normal position by displacement of the liquid drawn into sleeve 60 past the nar row clearance between the piston and sleeve. However, if such heavier overloads are continuing in nature, a second circuit interrupting operation will succeed the first, and this time notched piston 58 will be raised a further amount, and finally will be raised into engage ment with the knee of toggle levers l8 and 20 to move the knee of the toggle overcenter, and per mit lockout spring 22 to rotate spring support I 6 in a counterclockwise direction, thus removing. the reaction point for reclosing spring E i, and preventing reclosure of the contacts. This results in clockwise movement of handle H on shaft 24, so that the handle projects below hood l2 and gives a visual indication of the condition of the breaker. by manually moving handle M by the use of a hookstick or the like inserted in hookeye 16 of the handle, to rotate the handle in a counterclockwise direction and move toggle levers l 8 and 20 back overcenter to the position shown in Fig. 1.

Preferably, all parts of the breaker are suspended from cover casting ill, for example as by supporting columns 1'! connecting the cover casting with the supporting frame for solenoid coil 44, which in turn has spaced supporting plates 19 for supporting cap 35 of the arc chamber. Breaker casing 2 is adapted to be filled with an arc-extinguishing liquid, such as oil, up to the level indicated by the dot and dash line, and there is preferably provided a float 68 having an indicating rod thereon adapted to extend into a sight glass H3 supported beneath hood [2 of the breaker, so as to visually indicate the liquid level at the exterior of the casing.

As previously indicated, this invention is concerned with the elimination of the undesirable pumping action in a breaker or" the type thus far described, which may occur under certain conditions as described in the operation thereof. This is accomplished in accordance with this invention in an extremely simple manner by the use of the particular contact construction illustrated. This contact constructionincludes what may be termed the fixed contact of the breaker comprising a contact screw 80, threadedly mounted in an aperture provided in cap 36 of the arc chamber. Contact screw 80 is provided with a reduced portion within the arc chamber on which is threadedly mounted a contact cap 84. Contact rod 30 is provided at its lower end with a bore in which is threadedly received a contact screw 86, having a flanged head 88 adaptedto engage the contact head 84 in the closed circuit position of the breaker. The stationary contact structure is provided with a genbreaker y Obviously be reset 1 between them. As soon as the arcing contact (ill erally U-shaped arcing contact of resilient material having its bight portion apertured as at 9|, so as to be slidably mounted on the reduced portion 82 of contact screw ea. The leg portions of the arcing contact structure extend upwardly and are provided at their free ends with opposed arcing contact portions $2 of some good arc-resistant material, such for example as a tungsten alloy. The arcing contact is normally maintained at the position shown in Figs. 1 and 3 by a coil compression sprin 94 which reacts between contact head 84 and the bight portion of the arcing contact structure to bias the latter downwardly into engagement with a flange on contact screw 80.

The closed circuit position of the arcing contact structure is illustrated in Fig. l, and the operation thereof in opening the circuit is such that when contact rod 30 is moved upwardly, contact head 88 thereon moves away from stationary contact cap 84, but the circuit is not interrupted because the flange on contact head 88 is engaged beneath arcing contact portions 92, which results in raising the arcing contact structure while compressing spring as to the position shown in Fig. 2. When the parts reach the position illustrated in Fig. 2, further upward movement of the arcing contact structure is prohibited by reason of spring e4 going solid, or by engagement of the bight portion of the arcing contact structure with the lower end of contact cap 84, .so that continued upward movement of contact rod 30 causes the flange on contact head 88 to separate arcing contact portions 52 and to move upwardly structure is free of contact head 88, spring 94 will return it to the position illustrated in Fig. 3, thus introducing a gap between the stationary and moving contact structures of the breaker which is of a predetermined length, and at a rate independent of the rate of movement of solenoid core 5%, because it is produced solely by spring 94. The amount of movement of contact rod 30 necessary to produce this separation of thebreaker contact structures should be at least enough to move latch plate 6'! onto the enlarged portion of latch rod 13, so that there will be a time delay interposed before the breaker contacts are reclosed.

By thus providing the particular stationary contact structure disclosed herein, a predetermined amount of contact separation is obtained on each circuit interrupting operation, entirely independently of the degree of energization of solenoid coil 4%, and at a rate which is also independent of the condition causing interruption. The fact that the contacts must be separated an amount sufficient to cause operation of time delay means for the reclosing operation, means that undesirable pumping of the breaker contacts is prevented, and sufficient time is provided for faults of a transient nature to clear themselves between a circuit opening and succeeding closing operation of the breaker. Moreover, the structure by which this result is obtained is quite simple and economical to manufacture, and may even be readily installed in existing breakers by merely changing the contact structure.

This invention may also be incorporated in the type of interrupter shown in Figs. 4 and 5 of the drawings. This interrupter is in many respects similar to that shown in J. M. Wallace Patent No. 2,352,048, issued on June 20, 1944, to the same assignee of this invention. Accordingly, for more detailed description of the construction and operation of certain of the parts, reference may be had to the aforesaid Wallace patent, while this description will be mainly confined to pointing out the application of this invention to a circuit interrupter of the type shown in the Wallace patent, and to such other diiferences as will be apparent. Certain of the parts of the interrupter shown in Figs. 4 and 5 which are like certain of the parts previously described in the interrupter shown in Figs. 1 to 3, will not be described again in detail, however like reference numerals are employed to designate such like parts.

The interrupter shown in Figs. 4 and 5 has a casing 2 like the interrupter of Figs. 1 to 3, and this casing has a cover casting 96 for the open top thereof, which casting is provided with a hollow portion across which extends a shaft 98 to be journalled in opposite side walls thereof. An actuating crank I80 is secured on actuating shaft 98, and is biased in a counterclockwise direction as viewed in Fig. 5, by reclosing springs I02 coiled about shaft 98. The reclosing springs thus act to bias actuating links I04 downwardly, the links being connected to actuating crank I by a pivot bolt I06, and being pivotally connected with contact rod 30 by a pivot pin I88, to bias the contact rod toward stationary contact cap 84. Pivot pin I88 has the ends thereof extended on opposite sides of contact rod '38, to be received in guide slots II8 provided in supporting plates II2, which, in turn are secured to the cover casting in insulated relation. Supporting plates II2 are secured at their lower ends, as by screws I I3, to a collar I I5 integral with an upper supporting plate structure II4 for a solenoid coil I28. The solenoid coil is supported between plate H4 and a lower supporting plate IIB, by bolts II8 (only one of which is shown) which clamp the coil between plates I I4 and I E6.

Solenoid coil I28 is provided with a. central bore in which is received a cylindrical solenoid core I2I, slidably mounted on contact rod 38. The upper end of solenoid core I2I has secured thereto an actuating sleeve I22 which terminates at its upper end in a cup-shaped portion I24. A guide bracket I2 5 is secured to cup-shaped portion I 24 and has an extension positioned in a guide slot III), for preventing rotation of actuating sleeve I22. A complementary cup-shaped portion I28 is secured to the upper end of contact rod 38, and a coil compression spring reacts between actuating sleeve I22 and contact rod 38, having the ends thereof received in cupshaped portions I24 and I28, respectively.

The circuit interrupter disclosed in the afore said Wallace patent is adapted to have the closing movement delayed by mechanical ticker means associated with actuating sleeve I22 and solenoid core I2 i. The interrupter illustrated in Figs. 4 and 5 difiers from the structure of the aforesaid Wallace patent, in that the time delay means is directly associated with the contact rod 38, by means of a supporting bar I32 which is rigidly mounted on pivot pin E08. Bar I32 supports a rack I34 by means of a pivot pin I36, for engaging and driving mechanical time delay ticker mechanism. For this purpose, rack I34 is biased by a spring I4! toward a pinion !42 secured on a shaft I44. Rack I34 is provided with teeth I38 for engaging pinion I42, and with a smooth portion I48, for a purpose to be described. A gear I46 is also mounted on shaft I44, and it is adapted to mesh with a pinion I48 to drive a escape gear I58, the movement of which is controlled by an oscillatable escapement ticker I52, pivotally mounted as at I53.

It will be observed that in this interrupter the electric circuit may be traced from cover casting 98, by Way of a conductor I54 to solenoid coil I20, then by a flexible conductor I56 to pivot pin I88 and contact rod 30, to contact screw 88 and fixed contact 80, to terminal screw 4. The solenoid coil is therefore connected in series in the circuit through the interrupter, so that upon the occurrence of an overload on the circuit which energizes coil I20 sufficiently to attract core I 2I, the core will be moved upwardly while compressing spring I38, with contact rod 30 being held in closed circuit position by reclosing springs I02. Upward movement of solenoid core I2I continues until the cup-shaped portion I24 on actuating sleeve I22 engages the cup-shapedmember I 28 on contact rod 30. Thereafter, continued upward movement or core I2I results in moving contact rod 30 upwardly to disengage the contacts and interrupt the circuit. In the normal closed circuit position of the interrupter shown in Fig. 4, the smooth portion I48 of rack I34 is positioned in engagement with pinion I42, so that no time delay effect is had on reclosing the contacts unless contact rod 30 is moved upwardly a distance sufiicient to engage teeth I38 of the rack with pinion I42. This movement of contact rod 30 is insured by use of the particular contact structure constituting this invention. In other words, since the contacts actually do not separate until contact rod 38 has moved from the position shown in Fig. 4 to the position shown in Fig, 5, this movement is taken advantage of to engage teeth I38 of the rack with pinion I42, so that if the overload condition is such that the arc is extinguished substantially as soon as the contacts are separated, the circuit will not reclose until a predetermined time thereafter, due to the engagement of rack teeth I38 with the ticker mechanism.

The circuit is automatically reclosed following a circuit interrupting operation by reclosing springs I82 which bias contact rod 38 in a direction to reclose the contacts; such reclosing movement, however, is delayed by operation of the time delay ticker mechanism. It is necessary, in order to prevent arcing during the circuit closing operation just prior to the time the contacts actually engage, that the final movement of contact screw 86 into engagement with fixed contact be relatively rapid, and it is for this reason that rack I34 is provided with smooth portion I48, so that it will disengage pinion I42 just prior to final engagement of the contacts in a circuit reclosing operation. It will be readily apparent that, without a contact structure, such as that illustrated in the drawings, on interruptions on low current, or low voltage, or both, where interruption occurs substantially as soon as the contacts separate, rack I34 would never be moved upwardly a distance sufficient to engage the teeth I38 thereof with pinion I42, and this would result in the undesirable pumping action of the breaker previously described. However, with the contact structure incorporated in the interrupter in accordance with this invention, the time delay means is always rendered effective to delay a circuit reclosing operation, because contact rod 38 always travels from the position shown in Fig. 4 to that shown in Fig. 5, a distance which is sufficient to cause rack teeth !38 to engage pinion I42 before the breaker contacts are separated. This conditions the time delay ticker mechanism for control of each reclosing operation under the influence of reclosing springs I02.

The interrupter shown in Figs. 4 and 5 may be provided with means such as an extended solid toothed portion of gear I46 which is adapted to engage pinion Mil after the gear has been advanced by a predetermined number of closely successive circuit interrupting operations to prevent further reclosure of the breaker, as in the aforesaid-Wallace patent. Also, in order to reset such lockout means in the event the overload condition clears before the breaker operates through such predetermined number of closely succeeding circuit interrupting operations, a return spring I55 is provided on gear shaft M4 to return gear I46 to a normal position. Such return of the time delay ticker mechanism by return spring I55 can occur when the breaker contacts are closed, because at this time rack smooth portion I40 presented to pinion I42. The interrupter, like that shown in the aforesaid Wallace patent, may also be provided with an actuating handle I58 at the exterior of cover casting 96 and rigidly mounted on shaft 98.

Having described preferred embodiments of the invention in accordance with the Patent Statutes, it is desired that the invention be not limited to these particular embodiments, inasmuch as it will be obvious, particularly to persons skilled in the art, that many changes may be made therein without departing from the broad spirit and scope of this invention. It is therefore desired that the invention be interpreted as broadly as pos sible, in accordance with the following claims.

We claim as our invention:

1. In an automatic reclosing circuit breaker, separable contacts mounted on relatively fixed and movable supports, respectively, electroresponsive means for moving said movable contact support in a direction to separate said contacts, said movable contact support being biased for movement in the opposite direction to automatically reclose the circuit in response to a circuit interrupting operation, means effective to delay reclosing movement of said one contact except for a small distance in its path of movement adjacent the other of said contacts, one of said contacts having lost motion relative to its support a distance greater than the aforesaid distance, means releasably connecting said contacts in the closed circuit position, resilient means associated with said one contact and adapted to be stressed by relative movement of said one contact and its support in response to movement of said movable contact support in a direction to separate said contacts, whereby when said connection is released at the end of said relative movement said resilient means will move said one contact away from the other a predetermined distance at least greater than the aforesaid small distance and at a rate which is independent of the rate of movement of said electroresponsive means to insure operation of said time delay means on each circuit reclosing operation.

2. In an automatic reclosing circuit breaker, separable contacts, electroresponsive means for moving one of said contacts away from the other, said one contact being biased toward the other of said contacts to automatically reclose the circuit in response to a circuit interrupting operation, a substantially U-shaped arcing contact member having the bight portion thereof slidably mounted on one of said contacts, the legs I34 has its of said arcing member having contact portions adapted to yieldably engage the other of said contacts in the closed circuit position, resilient means opposing relative movement of said arcing contact member and said one contact in a circuit opening operation, whereby relative movement occurs between said arcing contact member and said one contact during a circuit interrupting operation While stressing said resilient means until the limit of said relative movement is reached, whereupon said arcing contact mem-- her and other contact are pulled apart and separated at least a predetermined distance b said resilient means, and in reclosing the contacts said contact support is required to travel at least said predetermined distance beyond the point in its opening movement Where contact separation occurred before said contacts are engaged.

3. Contact structure, comprising an elongated main contact member having a contact portion at one end thereof, a substantially U-shaped arcing contact member having the bight portion thereof apertured so as to be slidably mounted between spaced limits on said main contact mem ber, resilient means biasing said arcing contact member to the limit of its movement awayfrom said one end of said main contact member, and said leg portions having arcing contact portions on the outer ends thereof which are located adjacent said contact portion when said arcing contact member is at said one limit of its movement.

4. Contact structure, comprising an elongated main contact member having a contact portion at one end thereof, a substantially UShaped arcing contact member having the bight portion thereof apertured so as to be slidably mounted between spaced limits on said main contact member, resilient means biasing said arcing contact member to the limit of its movement, away from said one end of said main contact member, said leg portions being resilient and having arcing contact portions on the outer ends thereof which are located adjacent said contact portion when said arcing contact member is at said one limit of its movement, and said arcing contact portions projecting from said leg portions toward each other to embrace a cooperating contact.

5. In an automatic reclosing circuit breaker, separable contacts, electroresponsive means for moving one of said contacts away from the other, said one contact being biased toward the other of said contacts to automatically reclose the circuit in response to a circuit interrupting operation, time delay means, means independent of said electroresponsive means for coupling said time delay means for movement with said movable contact at least during a portion of the circuit closing movement of said moving contact, means for rendering said time delay means ineffective to delay the final part of the closing movement of said moving contact, and means cooperable with said contacts and responsive during an attempted circuit opening operation to conditioning of said time delay means to delay closing movement of the movable contact for preventinga circuit interrupting operation of said contacts unless said time delay means is conditioned to delay closing movement of said movable contact 6. In an automatic reclosing circuit breaker, separable contacts, electroresponsive means for moving one of said contacts away from the other, said one contact being biased toward the other of said contacts to automatically reclose the circuit in response to a circuit interrupting operation, time delay means, means independent of said electroresponsive means for coupling said time delay means for movement with said movable contact at least during a portion of the circuit closing movement of said moving contact, means for uncoupling said time delay means and movable contact during the final part of the closing movement of said moving contact, and mechanical means cooperable with said contacts and responsive during an attempted circuit opening operation to conditioning of said time delay means to delay closing movement of the movable contact for preventing separation of said contacts until the portion of said movable contact to which said time delay means is coupled has moved at least a distance greater than that corresponding to said final part of the closing movement of said moving contact.

7. In an automatic reclosing circuit breaker, separable contacts, electroresponsive means for moving one of said contacts away from the other, said one contact being biased toward the other of said contacts to automatically reclose the circuit in response to a circuit interrupting operation, time delay means, means independent of said electroresponsive means for coupling said time delay means for movement with said movable contact at least during a portion of the circuit closing movement of said moving contact, means for uncoupling said tim delay means and movable contact during the final part of the closing movement of said moving contact, and at least one of said contacts having a lost motion mounting for preventing separation of said contacts until the portion of said movable contact to which said time delay means is coupled has moved at least a distance greater than that corresponding to said final part of the closing movement of said moving contact.

8. In an automatic reclosing circuit breaker, separable contacts, electroresponsive means for moving one of said contacts away from the other, said one contact being biased toward the other of said contacts to automatically reclose the circuit in response to a circuit interrupting operation, time delay means adapted when rendered effective to delay closing movement of said movable contact, said time .delay means being ineffective to delay contact closing movement for a predetermined distance at the end of said closing movement, means for rendering said time delay means effective only in response to movement of said movable contact in a direction to open the circuit at least said predetermined distance, and means cooperable with said contacts and responsive during an attempted circuit opening operation to conditioning of said time delay means to delay closing movement of the movable contact for preventing a circuit interrupting operation by said contacts until said time delay means is rendered effective.

9. In an automatic reclosing circuit breaker, separable contacts, electroresponsive means for moving one of said contacts away from the other, said one contact being biased toward the other of said contacts to automatically reclose the circuit in response to a circuit interrupting operation, time delay means adapted when rendered effective to delay closing movement of said movable contact, said time delay means being ineffective to delay contact closing movement for a predetermined distance at the end of said closing movement, means for rendering said time delay means eiTective only in response to movement of said movable contact in a direction to open the circuit at least said predetermined distance, and at least one of said contacts having a lost motion mounting for preventing a circuit interrupting operation by said contacts until said time delay means is rendered eiiective.

JAMES M. WALLACE. WELDON L. METZ.

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

UNITED STATES PATENTS Number Name Date 508,652 Thomson Nov. 14, 1893 896,210 James Aug. 18, 1908 1,519,403 Graves et a1 Dec. 16, 1924 1,745,717 Sadler Feb. 4, 1930 1,855,579 MacNeill Apr. 26, 1932 2,069,082 Walle Jan. 26, 1937 2,333,604 Wallace Nov. 2, 1943 2,352,048 Wallace June 20, 1944 2,414,796 Bresson Jan. 28, 1947 FOREIGN PATENTS Number Country Date 598,137 France Sept. 19, 1925

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