US3145283A

US3145283A - Load break device having interrupting quick break blades of substantially same length

Info

Publication number: US3145283A
Application number: US62662A
Authority: US
Inventors: Date Kazuo Henry; Alwin G Steinmayer
Original assignee: McGraw Edison Co
Current assignee: McGraw Edison Co
Priority date: 1960-10-14
Filing date: 1960-10-14
Publication date: 1964-08-18
Anticipated expiration: 1981-08-18

Description

3,145,283 EAK 3 Sheets-Sheet 1 ING INTERRUPTING QUICK BR K. H. DATE ETAL CE HAV BLADES OF SUBSTANTIALLY SAME LENGTH Aug. 18, 1964 LOAD BREAK DEVI Filed'oct. 14. 1960 INVENToRs.

H9200 Has/Ry @972' BY/ua//fv e, 57am/Meri@ K. H. DATE ETAL Aug. 18, 1964 3,145,283 QUICK BREA ME LENGTH LOAD BREAK DEVICE VING INTERRUPTING BLADES OF' SUBSTANTIALLY SA 3 Sheets-Sheet 2 Filed oct. 14, 1960 Aug- 18, 1964 H. DATE ETAL y 3,145,283

LOAD BREAK DEVIC HAVING INTERRUPTING QUICK BREAK Filed Oct. 14. 1960 BLADES 0F SUBSTANTI'ALLY SAME LENGTH 3 Sheets-Sheet 3 INVENTORS. M4200 ivf/VAD B975 United States Patent O LOAD BREAK DEVHCE HAVHNG INTERRUPTING QUHCK BREAK BLADES F SUBSTANTIALLY SAME LENGTH Kazuo Henry Date, South Miiwaukee, and Alwin G.

Steinmayer, Milwaukee, Wis., assignors to McGraw- Edison Company, Milwaukee, Wis., a corporation of Beimvare Filed Utet. 14, 1960, Ser. No. 62,662 6 Ciairns. (Cl. 20h- 146) This invention relates to switching devices and, more particularly, to load break disconnecting switches.

Load break disconnecting switches generally comprise a disconnect switch having a circuit interrupter in parallel with its main disconnect contacts and which is adapted to interrupt the circuit after the switch has been opened. The provision of a parallel circuit around the main disconnect contacts while they are opening, eliminates the tendency for an arc to be struck between the stationary contact jaw and the movable switch blade if the switch is opened under load. The circuit interrupter usually comprises a movable contact coupled to the switch blade and actuable upon the movement thereof and a relatively xed contact disposed in arc extinguishing structure.

The type of disconnect switch to which the instant invention applies, is provided with a pair of quick break blades, one of which is pivotably mounted on the disconnect switch blade and the other of which is disposed in an arc chute. After the switch blade has been moved a predetermined distance toward its open position, the quick break blades are constructed and arranged to part and rapidly pivot in opposite directions thereby quickly elongating the arc to facilitate interruption.

In order to effectively interrupt an arc and prevent restrike after the system current has gone through current zero, the contact separation and dielectric build-up across the gap must increase at a suflicient rate to withstand the recovery voltage regardless of its rate of rise or the contact position when the current passes through zero. It can be seen, therefore, that contact speed is an important element in rapid current interruption. This is especially critical in capacitive circuits whereat one-halt cycle after current zero the voltage across the gap rises to twice peak line voltage because of the voltage across the charged capacitors.

It is an object of the invention to provide rapidly separating arc interrupting contacts for a load break disconnect switch.

It is a further object of the invention to provide a load break disconnect switch having a pair of low inertia quick break blades arranged for rapid pivotal movement in opposite directions for arc interruption.

Another object of the invention is to provide current interchange structure for the rotatable quick break blades of a load break disconnect switch.

A further object of the invention is to provide antirebound means for a load break disconnect switch having a pair of quick break blades adapted to rotate rapidly in opposite directions.

These and other objects and advantages of the invention will become more apparent from the detailed description of the invention taken with the accompanying drawings in which:

FIG. 1 is a side elevational view, with parts broken away, of the load break disconnect switch embodying the instant invention;

FIG. 2 is a top plan view of the device shown in FIG. 1;

FIG. 3 is a top segmented View, partly in section, illustrating the various current interchange and anti-rebound structures according to the instant invention;

FIG. 4 is an elevational view, with parts broken away,

3,145,283 Patented Aug. 18, 1964 ice of the disconnect switch self-aligning contact structure; and

FIG. 5 is a View taken along lines 5 5 of FIG. 4.

Referring to the drawings in greater detail, the invention is illustrated in connection with the combination of, an air disconnect switch, designated generally by the reference numeral 10, and a load interrupting device 11. The disconnect switch 10 includes a pair of parallel switch blades 12 pivotally mounted on a conductive hinge joint 14, which, in turn, is mounted atop a first porcelain bushing 16. A stationary contact jaw 18 is disposed atop a second porcelain bushing 20 and is engageable by the switch blades 12 when the latter are moved into their closed position seen in FIG. 1. Terminal pad 25 is also secured to the upper end of bushing 16 and is adapted to receive a line conductor (not shown). Contact jaw 18 may be provided with a releasable latch (not shown) for preventing unintentional movement of switch blades 12 under the iniiuence of magnetic forces incident to heavy currents.

The hinge assembly 14 includes a base portion 22 aixed to bushing 16 and a body portion 24 to which the switch blades 12 are hingedly mounted by means of a pivot bolt 26 and a nut 27. Current transfer between the body portion 24 of hinge member 14 and the switch blades 12, is accomplished by means of a pair of helically wound annular current interchange springs 28 composed of a suitable conductive material and disposed in a pair of annular grooves 29 formed in the lateral sides of body portion 24.

Body portion 24, switch blades 12, pivot bolt 26 and nut 27 are constructed and arranged so that the distance between the bottom of grooves 29 and the inner sides of switch blade 12 is less than the outside helical diameter of the current interchange springs 28. This forces the individual convolutions of spring 28 to lay over at an angle relative to their helical axis whereby the resiliency of said springs provides contact pressure with body portion 24 and switch blades 12. Thus, current transfer is elected between body portion 24 and switch blades 12, through a large number of parallel paths comprising the individual spring convolutions of springs 28. A more detailed description of the contact structure just defined may be found in copending application Ser. No. 847,263, tiled October 19, 1959, now Patent No. 3,056,101, and which is assigned to the assignee of the instant invention.

Referring specifically to FIGS. 4 and 5, the stationary contact jaw 18 is shown to include a body portion 30 and a base portion 32 which is aiiiXed to porcelain insulator 20. In addition, an interrupter mounting plate 33 is secured between base 32 and bushing 20 and includes an integral terminal pad 34 for connection to the other line wire (not shown).

Current interchange structure 35, for rendering contact' jaw 18 self-aligning relative to the switch blades 12, is disposed in recesses 36 formed in the opposite sides of the body portion 30 of stationary contact jaw 18 and each includes a helically wound conductive current interchange spring 37 and a contact plate 38. Each of the current interchange springs 37 is disposed in a circular groove 40 formed on the inner surface of recess 36. Contact plates 38 are also circular and each has an embossed rim 42 engageable with retaining rings 44 aflixed to the peripheries of recesses 36 and which hold plates 38 in engagement with the convolutions of their associated current interchange springs 37.

A plurality of dimples 46 are formed in the outer surface of each of the contact plates 38 and extend toward the switch blade 12 to provide points of contact therewith.

The lower portion of each of the grooves 40 is V-shaped so that they will contact each of the convolutions of their associated springs at two points. In this manner, a pair of parallel current paths are provided through each spring convolution thereby substantially lowering the voltage drop acrossl the interchange structure and also reducing the heat generated in the spring itself. Retaining rings 44 are so located relative to Agrooves 40 that the distance between contact plates 38 and the inner portion of grooves 49 is smaller than the outside helical diameter of the spring 37 so that each of the spring convolutions is forced to lay over at an angle relative to its helical axis. Here again, the inherent resiliency of springs 37 provides contact pressure with the contact plates 38 and the body portion of contact jaw 18.

When the switch blades 12 are in their open position the current interchange springs 37 force contact plates 38 outwardly until the rims 42 engage the retaining rings 44. This will allow the springs 37 to straighten out somewhat but the gap between contact plates 38 and grooves 4t) will be insuiiicient to allow them to assume a normal position relative to their helical axes. When switch blades 12 are returned to their closed position they are guided into alignment with the current interchange structures 3S by slanting surfaces 48 formed o n the upper end of body portion 3b. When dimples 46 are engaged, each of the Contact plates 38 will be forced inwardly toward grooves 40 thereby causing current interchange springs 37 to lay over at a greater angle which increases the contact pressure between dimples 46 and the switch blades 12 as well as between the current interchange springs 37 and the contact plates 33, on the one hand, and the body member 30 on the other.

It will be appreciated that the current interchange structure 3S just described allows a large degree 0f misalignment between switch blade 12 and stationary contact jaw 18 without a substantial reduction of its current transferring abilities because each of the contact plates 38 floats on its associated current interchange spring 37. As a result, the contact plates 3d arerockable as well as movable axially of grooves 40. ln addition, because each of the contact plates 33 is provided with three dirnples 46, three points of contact with each of the switch blades 12 will be maintained even through the switch blades 12 are closed in at an angle relative to contact jaw 18.

From the foregoing it will be apparent that the current path through the disconnect switch 1b is from terminal pad 25, through the body portion 24 of hinge member 14, the current interchange springs 28, the switch blades 12, the contact plate 38, the current interchange springs 37, the body portion 3i), and out of the rear terminal pad 34.

Turning now to the load interrupter 1i it is shown to include a first quick break blade 50 pivotally mounted on one of the switch blades 12 and a second quick break blade 52 pivotally mounted in an arc chute 54 disposed adjacent the stationary contact jaw 18. For purposes to be pointed out hereinbelow, each of the blades 50 and 52 is of substantially equal length and has a relatively thin cross-section. In addition, each of the blades 5t) and k52 is composed of a light weight material such as an aluminum alloy and is provided with a copper tungsten arcing tip 53.

The arc chute 54 comprises a pair of complementary plates 55 of any suitable insulating material and each is preferably lined with a substance capable of evolving an arc extinguishing gas when subject to an arc, such as, a fibre, synthetic resin, or the like. A spacer member '56 is provided between plates 55 and along three of the edges thereof for maintaining them in spaced relation when they `are secured together by any suitable means, such as rivets S7. The arc chute 54 is supported adjacent the stationary contact jaw'18 by a conductive supporting bracket 59 integral with mounting plate 33 and extending upwardly therefrom.

The first quick break blade 50 is pivotally mounted on one of the switch blades 12 by means of a hinge assembly 60 which is shown in FIG. 3 to include a rod 62 aiiixed to blade 5d and a cylindrical housing 64 aiiixed to switch blade 12. Current is transferred between rod 62 and housing 64 by means of a pair of current interchange springs 66 disposed in a pair of annular V-incross-section grooves formed on the inner surface of housing 64. The depth of grooves 68 are less than the outside helical diameters of current interchange springs 66 so that each of the convolutions of said springs are forced to lay over at an angle relative to their helical axes. This provides bearing pressure between the springs 66 and the shaft 62 and sleeve 64. A torsion spring 70 surrounds housing 64 and engages the switch blade 12 and quick break blade 56 for biasing the latter into engagement with a resiliently mounted stop 72.

Stop 72 includes a massive head portion 73, a reduced waist portion 74 and a stem portion 76 which extends through an aperture 78 in switch blade 12. The base 79 of waist portion 74 is resiliently urged against the side of switch blade 12 by a compression spring 30 which surrounds stem portion 76 between the opposite side of switch blade 12 and a washer S1 aiiixed to the end of stem portion '76.

A hinge assembly 83 identical to the hinge assembly 60 is aiiixed to conductive bracket 59 and extends through one of the plates 55 for pivotally supporting the second quick break blade 52 within arc chute 54. A torsion spring 86 in bearing assembly S3 (the end of which is shown in FIG. l) resiliently urges the second quick break blade 52 against a stop member 88 substantially identical with stop member 72 and which is resiliently supported on bracket member 59 and extends through an aperture in the side of plate 55.

When the disconnect switch is in its closed position, shown by full lines in FIG. l, the first quick break blade 50 is parallel to switch blade 12 and in engagement with stop 72. The second quick break blade 52 is in engagement with stop 88, also as shown by fuli lines in FiG. 1. The tips 53 of blades 'Sti and S2 are, however, spaced apart so that they carry no current when the switch blades 12 are in their closed position.

As the switch blades 12 are moved toward open position by exerting a force upon pull ring 90, the switch blades 12 will begin to move out of engagement with the stationary contact jaw 1d. Prior to the point at which the switch blades 12 become disengaged from stationary contact jaw 18, the quick break blades 50 and 52 will engage thereby providing an auxiliary current path around stationary contact jaw 18. This auxiliary path is from terminal pad 25, through hinge member 14, switch blades 12, hinge assembly dii, quick break blades 5d and 52, hinge assembly S3, bracket member 59, and out terminal pad 34. After the auxiliary load path has been established, further movement of switch blade 12 towards its fully open position disengages it from the stationary contact jaw 18.

Torsion springs 7d and 8e are so proportioned that as switch blade 12 rotates toward its open position, quick break blade 5'@ will remain in parallelism therewith and quick break blade 52 will be pivoted in a clockwise direction. This will continue until quick break blade 52 engages a resilient stop 32 identical with stops 72 and 8S, described above, whereupon further rotation thereof is prevented. When blade 52 is in this position, indicated by the reference numeral 52 in FG. l, the torsion spring 36 will be fully loaded. Continued rotation of switch blades 12 will then cause relative rotational movement between switch blade 12 and quick break blade 5d until they achieve their intermediate positions shown by phantom lines and indicated by reference numerals 12 and Sti respectively in FIG. l. When blade S0 is in this position, the torsion spring 70 will also be fully loaded and the tips 53 of blades Si? and 52 will just be in engagement. Additional pivotal movement of switch blades 12 will cause the tips 53 of quick break blades 5t) and 52 to disengage drawing an arc therebetween. Torsion springs 70 and 68 will then cause the blades t) and 52 to move rapidly in opposite directions and toward their respective stops 72 and 88 thereby rapidly elongating the arc so that interruption is enhanced. In addition, quick break blades 5t) and S2 will part at a point between plates 55 so that the arc will be confined and controlled within the are chute 54.

In addition, the massive heads and the resilient mountings of stop members 72 and 88 will absorb the energy of quick break blades 50 and 52 respectively thereby elimi nating the possibility that either will rebound which would bring them into proximity and thereby increase the possibility that the arc would be restruck.

Upon reaching its fully open position, the quick break blade Si) will again be in parallelism with switch blade 12 as shown by phantom lines and indicated by the reference I numerals Sil and 12 in FIG. 1. The second quick break blade 52, on the other hand, will return to its initial position shown by full lines.

When the switch blade 12 is pivoted toward its closed position the quick break blades Si) and 52 will engage thereby re-establishing the auxiliary current path, prior to the engagement of the switch blades 12 with the stationary contact jaw 18. Also, the spring which biases stop 72 is made to exert a greater force than the spring which 'biases stop 88 so that las switch blades 12 are moved into their fully closed position, quick break blade 5t) will force quick break blade 52 and stop 82 to deflect to their positions shown by phantom lines and indicated by the reference numerals 52 and 88 respectively. Arrter the tip of blade 5) passes the tip of blade 52, the resilient mounting of stop 88 returns quick break blade 52 to its initial position shown by full lines. The device is thereby reset for the next operation. In this manner, also, the auxiliary load path is opened so that all of the current is carried through the disconnect switch 1?. It can be seen, therefore, that current is carried through the quick break blades 5t) and 52 only during an opening or reclosing operation. It will be appreciated, too, that resilient stops 72 and 88 perform the functions of absorbing the energy of the quick break blades and also for allowing the resetting thereof.

It will be appreciated that in order to obtain the quickest possible acceleration of the quick break blades 5t! and 52, their moments of inertia must be as small as possible. Since these blades can be considered thin rods of mass M and length L their moments of inertia are given by the expression 1/sMLe Hence, in order to limit their moments of inertia, both the mass and length of each blade must be held to a minimum. However, in order to get the desired blade tip separation for any given angle of blade rotation, the pivotal axes of the two blades must be a predetermined distance apart at the moment of separation. It can be seen `from FIG. l that this distance is also the total length of the blades 50 and 52. As a result, the total length of the blades 50 and 52 is iixed by considerations other than acceleration. Therefore, because the total moment of inertia of blades 50 and 52 is proportional to the sum of the squares of their lengths, and because this value is the smallest for any given total length of the two blades when their lengths are equal, the smallest total moment of inertia and hence the most rapid contact separation is achieved when the lengths of the blades 50 and 52 are substantially equal. In addition, the mass of these blades is `further limited by fabricating them of an extremely light weight material and with a very thin cross section. For the latter reason, it is desirable that the blades 50 and 52 carry current only during a switch opening or reclosing operation.

Although only a single embodiment of the invention has been shown and described, it is intended to cover in the appended claims al1 modifications and embodiments of the various aspects of the instant invention that fall within the scope of the invention.

We claim:

l. In a load interrupting device, a disconnect switch, said disconnect switch including stationary contact means and switch blade means mounted for pivotal movement into and out of engagement with said stationary Contact means, a circuit interrupter mounted adjacent said disconnect switch and including an arc chute, a rst elongate contact element pivotally mounted about one end on said circuit interrupter with its other end disposed within said arc chute and electrically connected to said stationary contact means, a second elongate contact element pivotally mounted about one end on said disconnect switch externally of said are chute and with its other end disposed within said arc chute, said second contact element being electrically connected to said switch blade means, spring means resiliently urging said contact elements to pivot in opposite directions toward their positions when said switch blade means is in its closed position, said contact elements being in engagement to provide an auxiliary current path around said stationary Contact means prior to the disengagement therefrom of said switch blade means, pivotal movement of said switch blade means causing said contact elements to move against each other and said spring means and away from their initial positions, said Contact elements disengaging after said switch blade means has pivoted through a predetermined angle whereby saidV Contact elements are each free for rapid movement toward their initial positions under the influence of said spring means to interrupt said auxiliary current path, said contact elements being of substantially equal length.

2. In a load interrupting device, a disconnect switch, said disconnect switch including stationary Contact means and switch blade means mounted for pivotal movement into and out of engagement with said stationary contact means, a circuit interrupter mounted adjacent said disconnect switch and including an arc chute, a first elongate contact element pivotally mounted within said arc chute and electrically connected to said stationary contact means, a second elongate contact element pivotally mounted on said switch blade means, said contact elements being disposed in an initial angular position relative to each other with their free ends spaced apart when said switch blade means is in its closed position, spring means resiliently urging said contact elements to pivot in opposite directions toward said initial position, pivotal movement of said switch blade means toward its open position moving the free ends of said contact elements into engagement thereby providing an auxiliary current path around said stationary contact means, prior to the disengagement therefrom of said switch means, continued pivotal movement of said switch blade causing said contact elements to move against the influence of said spring means and away from their initial positions, said contact elements disengaging after said switch blade means has pivoted through a predetermined angle whereby said contact elements are each free for rapid movement toward their initial positions to interrupt said auxiliary current path, said contact elements being light weight and of substantially equal iength.

3. In a load interrupting device, a disconnect switch, said disconnect switch including stationary contact means and switch blade means mounted for pivotal movement into and out of engagement with said stationary contact means, a circuit interrupter mounted adjacent said disconnect switch and including an arc chute, a first contact blade pivotally mounted about one end and having its other end within said arc chute and electrically connected to said stationary Contact means, a second contact element pivotally mounted about one end on said switch blade means and having its other end disposed within said arc chute and spaced from the other end of said rst Contact blade when said disconnect switch is in its closed position, said contact blades being of substantially equal length, said first and second contact blades each having an initial position relative to said switch blade and said arc chute when said switch blade is in its closed position,

rst and second spring means resiliently urging said irst and second contact blades respectively to pivot in opposite directions and toward their initial positions, the initial pivotal movement of said switch blade means toward its fully open position moving the other ends of said contact blades into engagement thereby providing an auxiliary current path around said stationary contact means prior to the disengagement of said switch blade therefrom, continued pivotal movement of said switch blade causing said iirst and second Contact blades to pivot against the influence of said first and second spring means and away from their initial positions, said contact blades disengaging after said switch blade means has pivoted through a predetermined angle whereby said contact blades are each free for rapid movement toward their initial positions to interrupt said auxiliary current path, the pivotal movement of said switch blade toward its closed position engaging said contact blade prior to its reengagement with said stationary contact means, said contact blades moving out of engagement and into their initial positions after the re-engagement of said switch blade means and said stationary contact means.

4. in aload interrupting device, a disconnect switch, said disconnect switch including stationary contact means and switch blade means mounted for pivotal movement into and out of engagement with said stationary contact means, a circuit interruptor mounted adjacent said disconnect switch means and including an arc chute, irst and second resiliently supported mass means mounted within said arc chute and on said switch blade respectively, a first Contact element movably mounted within said arc chute and electrically connected to said stationary contact means, a second. Contact element movably mounted on said switch blade means, said first and second contact elements comprising relatively elongate thin members having equal lengths, spring means resiliently urging said contact elements into engagement with their associated mass means, said contact elements being normally disengaged and movable into engagement to provide an auxiliary current path around said stationary contact means prior to the disengagement therefrom of said switch blade means upon a switch opening operation, pivotal movement ot said. switch blade causing said contact elements to move against the inluence of said spring means and away from their associated mass means, said contact elements disengaging after said switch blade means has pivoted through a predetermined angle whereby said contact elements are each tree for rapid movement toward their associated mass means to interrupt said auxiliary current path, said resiliently supported mass means absorbing the energies ot said contact elements to prevent rebound thereof.

5. ln a load interrupting device, a disconnect switch, said disconnect switch including stationary Contact means and switch blade means mounted for pivotal movement into and out of engagement with said stationary contact means, a circuit interrupter mounted adjacent said stationary contact means and including an arc chute, iirst and second resiliently supported mass means mounted within said arc chute and on said switch blade respectively, a first quick break blade pivotally mounted within said are chute and electrically connected to said stationary contact means, a second quick break blade pivotally mounted on said switch blade means and spaced from said rst quick break blade when said disconnect switch is in its closed position, rst and second spring means resiliently urging said first and second quick break blades respectively into engagement with their associated mass means, pivotal movement of said switch blade means toward its open position moving the free ends of said quick break blades into engagement thereby providing an auxiliary current path around said stationary contact means, coneri' tinued pivotal movement of said switch blade means causing said quick break blades to pivot against the influence of their respective spring means and away from their associated mass means, said quick break blades disengaging after said switch blade means has pivoted through a predetermined angle whereby said quick break blades are each free for rapid pivotal movement toward their associated mass means to interrupt said auxiliary load path, said rst and second resiliently supported mass means absorbing the energies of said quick break blades to prevent rebound thereof, the pivotal movement of said switch blade toward its closed position engaging said quick break blades prior to the re-engagement of said switch blade means with said stationary Contact means, said first resiliently supported mass means being yieldable in a direction opposite to the direction of move- 'ment of said first quick break blade upon the interruption of said auxiliary load path so that said quick breal blades may move out or engagement and into their initial positions after the engagement of said switch blade means and said stationary contact means.

6. ln a load interrupting device, a disconnect switch, said disconnect switch including stationary contact means and switch blade means mounted for pivotal movement into and out of engagement with said stationary Contact means, a circuit interrupter mounted adjacent said stationary contact means and including an arc chute, first and second resiliently supported mass means mounted within said arc chute and on said switch blade respectively, a first quick break blade pivotally mounted within said arc chute and electrically connected to said station- Lry contact means, a second quick break blade pivotally mounted on said switch blade means, first and second spring means resiliently urging said rst and second quick break blades respectively into engagement with their associated mass means, pivotal movement of said switch blade means toward its open position moving the free ends oi said quick break blades into engagement thereby providing an auxiliary current path around said stationary contact means, said second spring means exerting a greater biasing force than said rst so that said rst quick break blade will be pivoted away from its mass means as said switch blade means moves toward its open position, stop means disposed in the path of said rst quick break blade to arrest the movement thereof so that said second quick break blade is forced to pivot relative to said -switch blade means, said quick break blades disengaging after said second quick break blade has pivoted through a predetermined angle whereby said quick break blades are each free for rapid pivotal movement toward their associated mass means to interrupt said auxiliary load path, said first and second resiliently supported mass means absorbing the energies of said quick break blades to prevent rebound thereof, the pivotal movement of said switch blade toward its closed position engaging said quick break blades prior to the re-engagement of said switch blade means with said stationary contact means, said iirst resiliently supported mass means being yieldable in a direction opposite to the direction of move- :lent ot said rst quick break blade upon the interruption of said auxiliary load path so that said quick break blades may move out of engagement and into their initial positions after the engagement of said switch blade means and said stationary contact means.

References Cited in the le of this patent UNITED STATES PATENTS 2,571,864 Graybill Oct. 16, 1951 2,683,875 Akelrad July 13, 1954 2,948,794 Fjellstedt et al. Aug. 9, 1960 3,064,107 Date Nov. 13, 1962

Claims

1. IN A LOAD INTERRUPTING DEVICE, A DISCONNECT SWITCH, SAID DISCONNECT SWITCH INCLUDING STATIONARY CONTACT MEANS AND SWITCH BLADE MEANS MOUNTED FOR PIVOTAL MOVEMENT INTO AND OUT OF ENGAGEMENT WITH SAID STATIONARY CONTACT MEANS, A CIRCUIT INTERRUPTER MOUNTED ADJACENT SAID DISCONNECT SWITCH AND INCLUDING AN ARC CHUTE, A FIRST ELONGATE CONTACT ELEMENT PIVOTALLY MOUNTED ABOUT ONE END ON SAID CIRCUIT INTERRUPTER WITH ITS OTHER END DISPOSED WITHIN SAID ARC CHUTE AND ELECTRICALLY CONNECTED TO SAID STATIONARY CONTACT MEANS, A SECOND ELONGATE CONTACT ELEMENT PIVOTALLY MOUNTED ABOUT ONE END ON SAID DISCONNECT SWITCH EXTERNALLY OF SAID ARC CHUTE AND WITH ITS OTHER END DISPOSED WITHIN SAID ARC CHUTE, SAID SECOND CONTACT ELEMENT BEING ELECTRICALLY CONNECTED TO SAID SWITCH BLADE MEANS, SPRING MEANS RESILIENTLY URGING SAID CONTACT ELEMENTS TO PIVOT IN OPPOSITE DIRECTIONS TOWARD THEIR POSITIONS WHEN SAID SWITCH BLADE MEANS IS IN ITS CLOSED POSITION, SAID CONTACT ELEMENTS BEING IN ENGAGEMENT TO PROVIDE AN AUXILIARY CURRENT PATH AROUND SAID STATIONARY CONTACT MEANS PRIOR TO THE DISENGAGEMENT THEREFROM OF SAID SWITCH BLADE MEANS, PIVOTAL MOVEMENT OF SAID SWITCH BLADE MEANS CAUSING SAID CONTACT ELEMENTS TO MOVE AGAINST EACH OTHER AND SAID SPRING MEANS AND AWAY FROM THEIR INITIAL POSITIONS, SAID CONTACT ELEMENTS DISENGAGING AFTER SAID SWITCH BLADE MEANS HAS PIVOTED THROUGH A PREDETERMINED ANGLE WHEREBY SAID CONTACT ELEMENTS ARE EACH FREE FOR RAPID MOVEMENT TOWARD THEIR INITIAL POSITIONS UNDER THE INFLUENCE OF SAID SPRING MEANS TO INTERRUPT SAID AUXILIARY CURRENT PATH, SAID CONTACT ELEMENTS BEING OF SUBSTANTIALLY EQUAL LENGTH.