US2886663A

US2886663A - Electric circuit interrupter

Info

Publication number: US2886663A
Application number: US586233A
Authority: US
Inventors: Alric H Powell
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1956-05-21
Filing date: 1956-05-21
Publication date: 1959-05-12
Anticipated expiration: 1976-05-12
Also published as: JPS336716B1

Description

May 12, 1959 A. l ow LL I 2,886,663

ELECTRIC CIRCUIT INTERRUPTER Filed May 21, 71956 2 Sheets-Sheet 1 33 Inventor:

. Alric H. 'Pow'll,

by W K I His ttorneg.

May 12, 1959 A. H. POWELL 2,886,663

ELECTRIC CIRCUIT INTERRUPTER Filed May 21, 1956 2 Sheets-Sheet. 2

Fiji/a.

Inventor: Alric H. Powell,

United States Patent O ELECTRIC cnzcurr INTERRUPTER Alric H. Powell, Lans downe, Pa., assignor to General Electric Company, a corporation of New York Application May 21, 1956, Serial No. 586,233 15 Claims. (Cl. 200-48) This invention relates to an electric circuit interrupter and, more particularly, to an interrupter of the type which can operate both as a disconnecting switch and as a device for interrupting substantial currents in the form of line charging currents, transformer magnetizing currents, and the like.

In certain known interrupters of this type, interrupting ability is imparted to an outdoor air-break disconnecting switch by providing the switch with an auxilary device which operates to produce contact separation at extreme high speeds. My invention is applicable to such an interrupter and especially to such an interrupter where in the speed and the extent of contact separation are the primary factors which determine the interrupting capacity of the switch.

Prior interrupters of this particular type of which I am aware have been subject to one or more of the following shortcomings. They have either had unsatisfactory operating characteristics under ice conditions; their interrupting ability has been limited by unduly low speeds of contact separation; or, contact-rebound or erratic operation has produced arc-reestablishment.

Accordingly, one of the objects of my invention is to provide a new and improved load-break disconnecting switch in which the above shortcomings have been obviated.

Another object is to produce the desired high-speed contact separation by means of a stored-energy type of auxiliary device which is charged during initial switchopening movement and in which the torque required for charging the device 'does not have extreme variations. By obviating the need for widely-varying amounts of charging torque, it is possible to minimize the peaktorque requirements for opening the switch. This is especially desirable where the switch is motor-operated, as it permits the use of a smaller motor than would otherwise be required.

Another object is to terminate opening movement of the high-speed parts of the switch in such a manner that the resulting forces do not subject the switch-supporting insulators to harmful cantilever loadings.

In carrying out my invention in one form, I utilize a switch of the type which comprises a main blade which is pivotally mounted on a hinge for swinging movement into and out of engagement with suitable stationary contact structure. An interrupting device which comprises an auxiliary blade electrically connected to said contact structure is stationarily mounted with respect to said contact structure. The auxiliary blade is mounted for pivotal motion about an axis located generally between the hinge and the contact structure, considered along a line joining the hinge and the contact structure, and is biased into a neutral position by spring means provided in the interrupting device. Force-transmitting means driven by opening motion of the main blade is provided for pivoting the auxiliary blade away from said neutral position to charge the spring means. During this springcharging interval the power circuit extends between the two blades. After a predetermined opening movement of the main blade, the auxiliary blade is released fromv driven relationship with the main blade. Such release allows the spring means quickly to discharge and separate the auxiliary bladefrom the main blade at high speed. This blade-separation produces an are which is quickly extinguished and prevented from harmfully restriking primarily as a result of the high-speed at which bladeseparation occurs.

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

Fig. 1 is a side elevational view showing a circuit interrupter constructed in accordance with one form of my invention.

Fig. 1a is an enlarged sectional view taken along the line 1a-1a of Fig. 1.

Fig. 2 is an enlarged plan view, partly in section, of a portion of Fig. 1 showing certain details of the interrupter.

Fig. 3 is a cross-sectional view taken along the line 3-3 of Fig. 2 and showing certain parts of the interrupter in a neutral position.

Fig. 4 is a cross-sectional view similar to Fig. 3 but showing the interrupter parts in a position through which they pass during a switch-opening operation.

Fig. 5 is an enlarged end view similar to Fig. 1 but illustrating a slightly modified form of my circuit interrupter.

Fig. 6 illustrates a further modification of my circuit interrupter.

Referring now to Fig. 1, the circuit interrupter shown therein comprises an outdoor air-break disconnecting switch 10. This switch 10 can be of any suitable conventional form but is illustrated as being of the type shown and claimed in Scheuermeyer Patent No. 2,531,165, assigned to the assignee of the present invention.

In general, this switch 10 comprises a plurality of spaced-apart insulating columns 11, 12 and 13 preferably formed of porcelain. The insulating columns 12 and 13 are stationary, whereas the column 11 is suitably mounted for rotation about its own vertical axis. The columns 11 and 12 support a conductive cross-brace 15 which is provided with a line terminal 16. The column 11 is rotatable relative to this cross-brace 15. The other column 13 supports a stationary jaw-type contact 18 which is provided with a line terminal 19.

The conductive members 15 and 18 are bridged by means of a main blade 20 which in Fig. 1 is shown in closed-circuit position. This main blade 26 is mounted for swinging movement about a stationary pivot or hinge 21 contained within a hinge joint 22 provided atop the column 12. Since the details of this hinge joint form no part of the present invention and are fully disclosed in the above cited Scheuermeyer patent, they have not been disclosed in the present application. It is believed sufficient merely to point out that the main blade 20, in addition to being mounted for swinging movement, is also mounted for rotation about its own axis within a blade-supporting hinge member 23 and that suitable means (not shown) are provided within the hinge joint 22 for maintaining the blade 20 and the cross-brace 15 in electrically-connected relationship.

Movement of the blade 20 is controlled by means of an operating mechanism generally indicated at 25. This mechanism 25 includes a crank 26 attached to a shaft 27 which is anchored to the rotatable insulating column 11 for rotation therewith. The mechanism 25 also includes a swivel link 28 universally connected to the crank 26 and pivotally joined to the hinge member 23 so as to form a toggle with the crank 26. If the main blade 20 is in its fully-closed position of 1 and the insulator 11 is rotated in the proper direction, the operating mechanism acts first to twist the blade 20 about its longitudinal axis and then to swing the blade in a counterclockwise opening direction about its pivot 21, all as described in detail in the above-cited Scheuermeyer patent. The blade-twisting action acts. to release the flattened outerend 20a of the blade from the pressure of the jawtype stationary contact 18' andalso acts to breakup any ice which might be formed on the stationary contact, thus permitting the blade to be swung relatively freely toward its open-circuit position.

For rendering the switch capable of interrupting substantial line currents, an auxiliary device constructed in accordance with one form of my invention, is provided and is supported upon the insulating column 13. This interrupting device 30 is electrically connected to the stationary contact 18 but is normally shunted out of the circuit when the switch blade 20 is in the closedcircuit position of Fig. 1.

The interrupting device 30 comprises an auxiliary blade in the form of a long tapered rod 32, preferably of high strength aluminum, which is electrically connected to the stationary contact structure. As shown in Fig. 2, this auxiliary blade 32 is suitably secured to a rotatable shaft 33 which is journaled at its opposite ends within a metallic housing 34 to provide a pivot axis 35 for the auxiliary blade. The housing 34 is mounted in laterally offset relationship to the stationary contact 18 by means of a metallic framework 31. This framework 31 in combination with the housing 34 electrically connects the auxiliary blade 32 to the stationary contact structure 18.

The auxiliary blade 32 is normally maintained in a neutral position, which is shown in Fig. 1, by the counterbalancing action of a plurality of

springs

36 and 37 located within the housing 34. In this neutral position of Fig. 1, the auxiliary blade 32 projects from its pivot axis 35 in a direction generally away from the main-blade hinge 21. As shown in Figs. 2 and 3, these springs act upon a crank 38 having a hub 33a which is pinned to the rotatable shaft 33. The springs 36 are heavy tension springs each having one end secured to the housing 34 and the other end secured to the outer end of the crank arm 38 through an adapter 39. This adapter 39 is piv otally mounted on the crank arm 38 by means of a pivot pin 40 and has suitable apertures for receiving the hooklike inner ends of the heavy tension springs 36. The other springs 37 are torsion springs each having one end anchored to the housing 34 and another end bearing against a thrust pin 41 secured to the crank 38. In the neutral position of Fig. 3, the torsion springs 37 tend to rotate the crank 38 together with the auxiliary blade 32 in a counterclockwise direction whereas the tension springs 36 tend to rotate the crank and auxiliary blade in an opposite or clockwise direction. For reasons which will soon appear, the torsion springs 37 are designed to have sufiicient strength to assure that the neutral position of the crank 38 will be located appreciably beyond dead-center position with respect to the tension springs 36, as can be seen in Fig. 3.

For interrelating the main blade 29 and the auxiliary blade 32, the main blade is provided with an L-shaped arcing horn 42 which is securely clamped to the tip of the main blade. When the main blade is in its fully closed position of Figs. 1 and 1a, the outer leg 43 of the arcing horn 42 extends generally downward and is spaced from the auxiliary blade 32. However, when switch-opening movement is initiated by twisting the main blade 20 about its longitudinal axisto release it,

from the jaw contact, the leg 43 moves into a horizontal position with its grooved outer end disposed in vertical alignment with the auxiliary blade 32 but still spaced apart from the blade 32. As the opening operation continues and the main blade 20 swings upward and counterclockwise about its pivot 21, it drives the grooved portion of the arcing horn 42 into engagement with the underside of the auxiliary blade 32. During the above interval, i.e., after the jaw contact has been released, the circuit between the blade 20 and the line terminal 19 had been maintained by the action of a hairpin-like resilient horn 44 bearing against the inner leg of the L- shaped arcing horn 42. Shortly after engagement with the auxiliary blade 32 occurs, however, the arcing horn 42 moves clear of the hairpin-like horn 44, and the circuit isthcn transferred to a path extending from the main blade 29, through the L-shaped arcing born 42 and then through the auxiliary blade 32. I

After engagement between the arcing horn 42 and the auxiliary blade 32 has occurred and counterclockwise swinging movement of the main blade 20 continues, the main blade 20 acting through the arcing-horn 42 lifts the auxiliary blade from its neutral position of Figs. 1 and 3 and begins to rotate it counterclockwise about its pivot axis 35. This counterclockwise rotation of the auxiliary blade begins to charge the heavy tension springs 36, which are coupled to the auxiliary blade, and such charging continues as counterclockwise rotation of the auxiliary blade continues. This charging operation is considerably aided by the fact that continued counterclockwise movement of the main blade causes the arcing horn 42 to slide progressively outwardly along theblade 32, thus progressively lengthening the efiective lever arm through which the main blade is acting to charge the tension springs 36.

When the two

blades

20 and 32 reach the dotted line position of Fig. l, tension springs 36 are then fully charged, as illustrated in Fig. 4, and continued counterclockwise motion of the main blade 20- will release the auxiliary blade 32 from driven relationship with the main blade. When such release occurs, the then-charged springs 36 drive the auxiliary blade 32 at an extreme high speed in a reverse or clockwise direction. The arc which is established between the tips of the two blades 29 and 32 is rapidly extinguished and harmful restrikes are prevented as a result of the insulating gap which is quickly introduced into the circuit by the high speed clockwise motion of the auxiliary blade 32.

An important factor which contributes in my switch to the extreme high speed at which the insulating gap is established is the particular location of the pivot axis of the outwardly-extending auxiliary blade 32. By locating this pivot axis 35 in a region generally between the mainblade hinge 21 and the stationary contact 18 considered along a line joining the hinge and the contact, the tip of the auxiliary blade, upon release, is permitted to move away from the entire length of the main blade at a nearmaximum speed. This is in contrast to certain prior designs wherein a similar blade, being pivoted at a point axially beyond the tip of the main blade, has moved in such a path that, upon release, its tip has first moved in a direction toward the main-blade hinge joint. This latter type of movement not only detracts from the effective speed at which the insulating gap can be established, but also tends to cause the upper terminal of the arc to run down the blade toward its hinge under heavycurrent interrupting conditions.

It will also be noted from Fig. 1 that the pivot axis 35 for the auxiliary blade 32 is located in the same region as the main blade when in its closed-circuit position. This factor permits the use of a longer auxiliary blade than would be possible if the blade pivot axis were located appreciably above the closed-circuit position of the main blade. Such added blade length also contributes to the blade tip velocity and hence to the effective speed at which the insulating gap is established.

Another factor which contributes to my extreme high blade speed is the fact that I use tension springs for accelerating and driving the blade 32. Such springs, as contrastedto, say, torsion. springs, can discharge their stored energy at an extremely high rate with a minimum of frictional resistance from the relatively-moving turns of the spring. The fact that the blade is of a tapered configuration and is of aluminum also contributes to the high rate at which the blade can be accelerated because of the low inertia properties of such a construction.

The kinetic energy of the high-speed auxiliary blade 32 is dissipated at the end of its clockwise opening travel by allowing it to swing past its neutral position and strike a buffer 50 secured to the top of the insulating column 13. This buffer 50 is preferably in the form of an angleiron 51 which is shown extending generally horizontally from the top of the insulating column 13. The upper surface of this angle iron 51 carries a facing 52 formed of a yieldable material, such as a suitable synthetic rubber or the like, and this yieldable facing 52 is adapted to be encountered by the auxiliary blade 32 along a major portion of the blade length. From Fig. 1 it will be apparent that the butter 50 is so located that those forces produced by the impact of the auxiliary blade 32 striking the buffer 50 act in a direction generally parallel to the longitudinal axis of the porcelain supporting column 13. This assures that the impact forces will load the porcelain column 13 for the most part in compression rather than in bending or tension. This is especially desirable in view of the well-known weakness of porcelain in bending and tension as compared to compression.

The angle-iron 51 of the buffer 50, as can be seen in Fig. 1, extends in a slightly inclined path for two reasons. First, this minimizes ice-formation on the buffer 50 by tending to prevent water from collecting on its top surface. Second, this slope assures that the auxiliary blade 32 will contact the yieldable face 52 in the region adjacent the insulating column 13 before contact occurs further out toward the blade tip. This assures that the brunt of the impact-produced forces will be applied in a region adjacent the insulating column 13, thus further reducing any tendency toward cantilever loading of the insulating column 13.

Dissipation of the kinetic energy of the high-speed auxiliary blade 32 is considerably aided by the presence of the torsion springs 37. As can be seen in Fig. 4, these torsion springs 37 follow the crank 38 through only a minor portion of the counterclockwise charging motion of the tension springs 36 (as a result of the interference provided by the side wall of housing 34). Thus, when the auxiliary blade is subsequently released, as previously described, these torsion springs 37 do not interfere with the desired high-speed initial opening-movement of the auxiliary blade 32. However, near the end of the opening stroke, the inner ends of the torsion springs are encountered by the thrust pin 41 attached to the crank 38, thus permitting the torsion springs to cushion the opening impact by absorbing some of the excess opening energy.

In addition to their shock-absorbing functions, the torsion springs 37 act to position the auxiliary blade 32 in the neutral position shown in Fig. 3, where the crank 38 is shown located considerably beyond its dead-center position with respect to the tension springs 36. By locating the initial crank position beyond dead-center instead of on or ahead of dead-center, initial counterclockwise movement of the auxiliary blade 32 is effective to significantly charge the tension springs 36, whereas if the opposite were the case, this initial movement would be essentially wasted insofar as charging of the tension springs 36 is concerned.

Although the tension springs 36 exert more opposition to initial blade movement in this beyond-center position than they would in a dead-center position, this difiiculty is overcome by the counterbalancing action of the torsion springs37. As a result of the aid provided by this counterbalancing action, little external eifort is normally required to initiate movement of the auxiliary blade in a direction to charge the springs 36. Thus, even with ice formed about the auxiliary blade 32, the peak-torque required for initiating movement of the blade 32 is not unduly high.

Once the tension springs 36 have been initially overcome with the aid of the counterbalancing torsion springs 37, the main blade exerts its efiort through a progressively lengthening lever arm, as previously described. Thus, as the tension springs are charged and their opposition increases, the elfective mechanical advantage increases, thus allowing the spring-charging operation to be performed without major variations in the torque required at the input end of the disconnect switch 10. This is especially desirable where the switch is motor-operated as it permits the use of a smaller operating motor than would otherwise-be required.

If desired, further reductions in the torque required for charging the tension springs 36 can be attained by reducing the friction between the arcing horn 42 and the auxiliary blade 32. To this end, I have shown in Fig. 5 an embodiment of the invention wherein the arcing horn 42 is provided with a roller bearing 53 for contacting the underside of the auxiliary blade 32 as the arcing horn moves therealong during a spring-charging operation.

Fig. 6 illustrates a modified form of my invention which enables me to obtain still higher speeds of initial contact separation. This modified form of the invention differs from the previously-described embodiment only in that a flexible arcing tip 32a has been applied'to the outer end of the auxiliary blade 32. This arcing tip is preferably constructed of a rod of spring copper alloy having a body 32b wound into the form of a torsion spring and a rod-like portion 320 projecting therefrom. The body portion 32b is suitably attached to a transverse pin 60 carried by the outer end of the auxiliary blade 32. A suitable stop 61 carried by the blade 32 is disposed beneath the rod-like portion 32c for engagement therewith,

The inclusion of this arcing tip 32a modifies the previously-described mode of operation only in the following respect. In the modified embodiment, when the L-shaped arcing horn 42 has completed its spring-charging operation and has released the blade 32 to permit clockwise opening movement of the blade, contact separation does not instantly occur. Actual electrical separation is delayed until the released auxiliary blade 32 has moved a suflicient distance to free the flexible arcing tip 32a from the L-shaped horn 42. Movement of the auxiliary blade 32 prior to this point wipesthe rod portion 320 of the arcing tip 32a along the horn 42, flexes the arcing tip, and also provides sufiicient time for the auxiliary blade 32 to be accelerated'to a relatively high speed. When the arcing tip 32a is finally freed, it whips open at an extremely high speed whichis equal to the instantaneous speed of pin 60 plus the speed of the arcing tip 3211 measured with respect to the pin 60. Even though the arcing tip 32a tends to rebound about the pin 60 at the end of its opening swing, any tendency of such rebound to shorten the insulating gap is more than ofiset by the high speed at which the pin 60 is then moving in a generally opposite, or contact-separating, direction.

It is to be understood that the auxiliary blade 32 does not significantly interfere with closing movement of the main blade 20. This is the case because the auxiliary blade 32 has sufficient yieldability in a direction parallel to its pivot axis 35 to permit the arcing horn 42, during closing, to slightly displace the auxiliary blade in the direction of its yieldability, thus allowing the main blade 20 to sweep by the auxiliary blade as it moves into closed position.

It will be further, apparent that the auxiliary device 30 is a self-contained unit which can be readily added to existing switches for the purpose of imparting interrupting ability to such switches.

While I have shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its 7 broader aspects and I, therefore, intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

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

1. In a circuit interrupter comprising contact structure and a hinge mounted in spaced-apart relationship, a conductive main blade pivotally mounted on said hinge for movement into and out of engagement with said contact structure, an interrupting device stationarily mounted relative to said contact structure and comprising a conductive auxiliary blade which is electrically connected to said contact structure, said auxiliary blade being mounted for pivotal movement about an axis which is located generally between said contact structure and said hinge considered along a line joining said hinge andsaid contact structure, spring means biasing said auxiliary blade into a predetermined neutral position wherein said blade projects from its pivot in a direction generally away from said hinge, means driven by pivotal movement of said main blade in an opening direction for pivoting said auxiliary blade away from said neutral position to charge said spring means, and means operable after a predetermined opening movement of said main blade for releasing said auxiliary blade from driven relationship with said main blade to permit said spring means to discharge and separate said auxiliary blade from said main blade at high speed.

2. The circuit interrupter of claim 1 in combination with energy-storing arcing-tip means mounted on said auxiliary blade for carrying current between said blades during initial movement of said auxiliary blade in a bladeseparating direction, said initial blade movement acting to charge said arcing-tip means and to cause said tip means to snap open after the occurrence of a predetermined amount of said initial blade movement.

3. The circuit interrupter of claimil in which the pivot axis for said auxiliary blade is located in the same region as the main blade when said main blade is in closedcircuit position. i

4. The circuit interrupter of claim 1 in which the pivot axis for said auxiliary blade is spaced no more than a minor distance from the longitudinal axis of said main blade when said main blade is in closed-circuit positron.

5. In a circuit interrupter comprising contact structure and a hinge mounted in spaced-apart relationship, a conductive main blade pivotally mounted on said hinge for movement into and out of engagement with said contact structure, an auxiliary blade electrically connected to said contact structure, a shaft located generally between said contact structure and said hinge considered along a line joining said hinge and said contact structure and providing a stationary pivot axis about which said auxiliary blade is pivotable, a crank mounted on said shaft and coupled to said auxiliary blade, at least one tension spring connected to said crank and biasing said auxiliary blade into a predetermined neutral position wherein said auxiliary blade projects from its pivot in a direction generally away from said hinge, means driven by pivotal movement of said main blade in an opening direction for pivoting said auxiliary blade away from said neutral position to charge said tension spring, and means operable after a predetermined opening movement of said main blade for releasing said auxiliary blade from driven relationship with said main blade to permit said tension spring to discharge and separate said auxiliary blade from said main blade at high speed.

6. In a circuit interrupter comprising contact structure and a hinge mounted in spacedapart relationship, aconductive main blade pivotally mounted. on said hinge for swinging movement into and out of engagement with said contact structure, a conductive auxiliary blade electrically connected to said contact structure, a shaft located generally between said contact, structure and saidv hinge and providing a stationary pivot axis about which said auxiliary blade is pivotable, a pivotally-mounted crank coupled to said auxiliary blade, at least one tension spring connected to said crank,.additional spring means counterbalancing said tensionvspring and positioning said auxiliary blade in a neutral position wherein said crank is located appreciably beyond dead center position with respect to said tension spring, means driven by pivotal movement of said main blade in an opening direction for pivoting said auxiliary blade away from said neutral position in a direction which moves said crank away from said dead center position thereby to charge said tension spring, and means operable after a predetermined opening movement of said main blade for releasing said auxiliary blade from driven relationship with said main blade to permit said tension spring to discharge and separate said auxiliary blade from said main blade at high speed.

7. In a circuit interrupter comprising contact structure and a hinge mounted in spaced-apart relationship, a conductive mainblade pivotally mounted on said hinge for swinging movement into and out of engagement with said contact structure, a conductive auxiliary blade electrically connected to said contact structure, a shaft located generally between said contact structure and said hinge and providing a stationary pivot axis about which said auxiliary blade is pivotable, a pivotally-mounted crank coupled to said auxiliary blade, first spring means connected to said crank, additional spring means counterbalancing said first spring means and positioning said auxiliary blade in a neutral position wherein said crank is located appreciably beyond dead center position with respect to said first spring means, means driven by pivotal movement of said main blade in an opening direction for pivoting said auxiliary blade away from said neutral position in a direction which moves said crank away from said dead center position thereby to charge said first spring means, and means operable after a predetermined opening movement of said main blade for releasing said auxiliary blade from driven relationship with said main blade to permit said first spring means to discharge and separate said auxiliary blade from said main blade at high speed.

8. In a circuit interrupter comprising contact structure and a hinge mounted in spaced apart relationship, a conductive main blade pivotally mounted on said hinge for swinging movement into and out of engagement with said contact structure, a conductive auxiliary blade electrically connected to said contact structure, means for mounting said auxiliary blade for pivotal movement about an axis which is stationarily located with respect to said contact structure, a pivotally-mounted crank coupled to said auxiliary blade, first spring means connected to said crank, additional spring means counterbalancing said first spring means and positioning said auxiliary blade in a neutral position wherein said crank is located appreciably beyond dead center position with respect to said first spring means, means driven by pivotal movement of said main blade in an opening direction for pivoting said auxiliary blade away from said neutral position in a direction which moves said crank away from said dead center position thereby to charge said first spring means, and means operable after a predetermined opening movement of said main blade for releasing said auxiliary blade from driven relationship. with said main blade to permit said first spring means to discharge and separate said auxiliary blade from said main blade at high speed.

9. The circuit interrupter of claim 8 in combination with means for freeing said crank from the bias of said second spring means after a predetermined movement of said crank away from said neutral position.

10. A circuit interrupter comprising an insulating column, contact structure mounted on said column, a conductive-main blade pivotally mounted for movement into and out of engagement with said contact structure, an interrupting device stationarily mounted relative to said contact structure and comprising a pivotally-mounted auxiliary blade which iselectrically connected to said contact structure, spring means biasing said auxiliary blade into a predetermined neutral position, means driven by pivotal movement of said main blade in an opening direction for pivoting said auxiliary blade away from said neutral position to charge said spring means, and means operable after a predetermined opening movement of said main blade for releasing said auxiliary blade from driven relationship with said main blade to permit said spring means to discharge and drive said auxiliary blade away from said main blade and toward said neutral position at high speed, yieldable buffer means mounted on said insulating column and operable after said spring-driven auxiliary blade has passed through said neutral position for intercepting said spring driven auxiliary blade in a position wherein the force produced by said interception acts in a direction generally parallel to the longitudinal axis of said insulating column, said buffer means projecting laterally from said column and being positioned to engage said auxiliary blade along a major portion of the blade length but first in a region near said longitudinal axis and then in a region more remote from said axis.

11. A circuit interrupter comprising an insulating column, contact structure mounted on said column, a conductive blade pivotally mounted for movement into and out of engagement with said contact structure, an interrupting device stationarily mounted relative to said contact structure and comprising a pivotally-mounted auxiliary blade which is electrically connected to said contact structure, spring means biasing said auxiliary blade into a predetermined neutral position, means driven by pivotal movement of said main blade in an opening direction for pivoting said auxiliary blade away from said neutral position to charge said spring means, means operable after a predetermined opening movement of said main blade for releasing said auxiliary blade from driven relationship with said main blade to permit said spring means to discharge and separate said auxiliary 'blade from said main blade at high speed, and bufler means mounted on and projecting laterally from said insulating column and having a yieldable abutment surface against which the auxiliary blade strikes along a major portion of the blade length after a predetermined blade-separating movement, said abutment surface extending in a direction generally perpendicular to the longitudinal axis of said insulating column and adapted to intercept the auxiliary blade in such a position that the forces produced by the impact act in a direction generally parallel to said longitudinal axis, engagement between said auxiliary blade and said abutment surface occurring in a region near said axis prior to its occurrence at more remote points.

12. An aum'liary device which is adapted to be mounted adjacent the stationary contact of a disconnecting switch for imparting interrupting ability to the switch comprising: A housing which is adapted to be connected 10 to said stationary contact, an elongated auxiliary blade located externally to said housing, means for pivotally mounting said auxiliary blade on said housing, a pivotally mounted crank located within said housing and coupled to said auxiliary blade, first spring means connected to said crank, additional spring means counterbalancing said first spring means and positioning said auxiliary blade in a neutral position wherein said crank is located appreciably beyond dead center with respect to said first spring means.

13. The auxiliary device of claim 12 in combination with means for freeing said crank from the bias of said second spring means after a predetermined movement of said crank away from said neutral position.

14. In a circuit interrupter comprising contact structure and a hinge mounted in spaced-apart relationship, a conductive main blade pivotally mounted on said hinge for movement into and out of engagement with said contact structure, an interrupting device stationarily mounted relative to said contact structure and comprising a conductive auxiliary blade which is electrically connected to said contact structure, said auxiliary blade being mounted for pivotal movement about an axis which is located generally between said contact structure and said hinge, spring means biasing said auxiliary blade into a predetermined neutral position wherein said blade projects from its pivot in a direction generally away from said hinge, means driven by pivotal movement of said main blade in an opening direction for pivoting said auxiliary blade away from said neutral position to charge said spring means, means operable after a predetermined opening movement of said main blade for releasing said auxiliary blade from driven relationship with said main blade to permit said spring means to discharge and separate said auxiliary blade from said main blade at high speed, an insulating column on which said contact structure is mounted, and buffer means also mounted on said insulating column and operable to intercept said springdriven auxiliary blade in a position wherein the impact forces produced by said interception are applied to said bufier means in a direction generally parallel to the longitudinal axis of said insulating column.

15. The circuit interrupter of claim 14 in which the pivot axis for said auxiliary blade is spaced no more than a minor distance from the longitudinal axis of said main blade when said main blade is in closed-circuit position.

References Cited in the file of this patent UNITED STATES PATENTS 1,919,065 Jacobs July 18, 1933 2,750,460 Kast June 12, 1956