US3582595A

US3582595A - Trip-free switch-operating mechanism

Info

Publication number: US3582595A
Application number: US872953A
Authority: US
Inventors: Manfred Stene
Original assignee: Erickson Electrical Equipment Co
Current assignee: Erickson Electrical Equipment Co
Priority date: 1969-10-31
Filing date: 1969-10-31
Publication date: 1971-06-01
Anticipated expiration: 1988-06-01

Abstract

A trip-free operating mechanism for a manual load break switch using an overcenter spring drive to open and to close the switch. On closing, the switch handle actuates the overcenter spring drive and charges a switch-opening spring, or other storage device, through an actuating mechanism that automatically latches both the opening spring and the handle as closed position is reached. An independent trip, which may be electrically operated by a solenoid and may also be manually operated, releases the opening spring to power the spring drive for opening of the switch; after the switch opens, the handle is released to fall freely to its open-switch position, serving as an external switch position indicator. The handle is not used directly to open the switch, but can be used as a means for manual operation of the trip mechanism; the handle can be moved to its fully open position only when the switch is fully open, and hence can be utilized in a safety interlock to prevent exposure of live switch parts.

Description

United States Patent [72] Inventor Manfred Stene Chicago, Ill. [2]] Appl. No. 872,953 [22] Filed Oct.3l, 1969 [45] Patented June I, 1971 {73] Assignee Erickson Electrical Equipment Co.

Chicago, Ill.

[54] TRIP-FREE SWITCH-OPERATING MECHANISM 9 Claims, 11 Drawing Figs.

[52] U.S.Cl 200/153, 335/25, 335/17 l [5]] Int. Cl H0lh 3/30, HOlh 3/54, H0lh2l/42 [50] Field of Search 200/153, 23, 67 B, 167; 335/24, 25, 76, 171; 337/74, 8; 185/37 [56] References Cited UNITED STATES PATENTS 3,073,929 l/l963 Hauser 335/25 3,l83,332 5/1965 Frink etal. 200/153(.23)

FOREIGN PATENTS 708,191 4/1954 Great Britain 200/l53(.23) 849,345 9/l960 Great Britain 200/1 53(.23)

Primary ExaminerRobert K. Schaefer Assistant ExaminerRobert A. Vanderhye Att0rneyKinzer, Dorn and Zickert ABSTRACT: A trip-free operating mechanism for a manual load break switch using an overcenter spring drive to open and to close the switch. On closing, the switch handle actuatcs the overcenter spring drive and charges a switch-opening spring, or other storage device, through an actuating mechanism that automatically latches both the opening spring and the handle as closed position is reached. An independenttrip, which may be electrically operated by a solenoid and may also be manually operated, releases the opening spring to power the spring drive for opening of the switch; after the switch opens, the handle is released to fall freely to its open-switch position, serving as an external switch position indicator. The handle is not used directly to open the switch, but can be used as a means for manual operation of the trip mechanism; the handle can be moved to its fully open position only when the switch is fully open, and hence can be utilized in a safety interlock to prevent exposure of live switch parts.

PATENTEU Jun 1 l97| SHEET 3 0F 6 m: vow \Q INVENTOR. MANFRE'D .S'TENE EFL L .5

PATENT-ED JUN SHEET 5 [IF 6 SWITCH OPENING L/-TRIP BY SOL- IoI 0R LEVER I26 TRIP LATCH H9 RELEAsED LEVER I32, SPRING I37 I EXPAND cw ROTATION DRIVEN BY SPRING I37 DRIVEN BY FOLLOWERS 75,76 C| cw ROTATION SPRING 53 TOGGLE CENTER7 SPRING 53 I coMPREss I EXPAND I LEVER 50 I cw ROTATION I LATCH I4I F'I-cw IMPETUS FROM I32 LE ER H5 UNLATCHEDq] w IMPETUS FROM SHINERTIAI HANDLE 5| cw CONTACTS 3I-33 CLOSED J FULL oPEN I Ff 8 SWITCH CLOSING J JRESET PosITIoN HANDLE 5| Icw I ccw RoTATIoN I LEVER H5 low I ccw RDTATIDN W LEVER I32} SPRING I37 I coMPREss-ccw RoTATIoN I DRIVEN BY HANDLE 5| DRIVEN BY SPRING 53

FoLLowERs

75,76 ccw I ROTATION I 'TOGGLE CENTER) sPRINesa I coIVIPREss ExPAND W LEVER 5o IROTATION ccwI -l43 LATCHED T0 N8 LATCH I4I LATcHED TO I32 LATCH H9 CONTACTS 3I-33S OPEN L CLOSED INVENTOR MANFRED TE/I/E TRIP-FREE SWITCH-OPERATING MECHANISM CROSSREFERENCES TO RELATED APPLICATIONS The switch-operating mechanism of the present invention utilizes, in its preferred form, the basic operating mechanism described and claimed in the copending application of Manfred Stene Ser. No. 667,044 filed Sept. 1, 1967 now U.S. Pat. No. 3,522,401, issued Aug. 4, 1970.

BACKGROUND OF THE INVENTION This invention relates to a new and improved trip-free operating mechanism for a load break switch and particularly to a switch-operating mechanism readily adaptable to both electrical and manual tripping.

Fused load break switches are frequently used as service en trance equipment and in other relatively high current applications; typically, multiple-pole switches of this kind may require interruption of currents of the order of 400 to 20,000 amperes. It is critically important that the contacts of these switches open and close rapidly to minimize arcing and thereby avoid pitting and deterioration of the switch contacts. The switches usually provide for latching of the switch contacts in closed position. The switch blades are relatively heavy and the mechanical forces entailed in opening and closing operations are often substantial.

In many applications, load break switches must include provision for opening of the switches from remote locations. The usual solution of this problem has been the provision of motor-operated switch mechanisms, even though it may not be essential to provide for remote actuation of the switches to closed position. Gear motors are often employed for this purpose but are slow in operation and delay contact separation by one-half second or more after the initial fault signal. In comparison, a spring-operated switch can effect contact separation in about one-tenth second.

There are other problems entailed in the operation of these heavy-duty switches, particularly where remote actuation is required. If the switches are constructed for manual as well as motor operation, there is a risk of injury to any personnel near the switches if the switch handles move unexpectedly and rapidly upon actuation of the switch mechanism from a remote location. Moreover, if the switch can be left in an intermediate position, internal arcing and consequent damage may occur.

SUMMARY OF THE INVENTION Accordingly, it is a principal object of the invention to provide a new and improved trip-free operating mechanism for a load break switch that is readily adaptable to remote actuation but that does not present a danger to personnel in the vicinity of the switch when remote actuation takes place.

A specific object of the invention is to provide a new and improved shunt trip mechanism for a load break switch that can be utilized with manually actuated switches or with motoroperated switches as the need arises.

Another specific object of the invention is to afford a new and improved quick-make quick-break switch suitable for ser vice entrance and other high-current applications that is inherently self-protected against teasing and against being left in an intermediate position in which the switch is neither fully open nor fully closed.

Accordingly, the invention relates to a trip-free operating mechanism for a load break switch of the kind comprising a fixed contact engageable by a movable contact that moves between fully closed and fully opened positions. The operating mechanism comprises a drive shaft rotatable in opposed switch-opening and switch-closing directions between closed and open positions. Overcenter spring drive means interconnects the drive shaft and the movable contact and is actuatable in two opposed directions across a center point in response to initial rotation of the drive shaft through a given minimum angle; this drive means quickly drives both the movable switch contact and the drive shaft to their respective open and closed positions. The mechanism includes an operating handle rotatable in opposed switch-closing and reset directions between open and closed positions. A switchopening energy storage device, preferably a spring, is connected to the drive shaft. Actuating means are provided for charging this storage device and for rotating the drive shaft through its minimum angle in its switch-closing direction to close the switch in response to rotation of the handle through a given are in its switch-closing direction. A first latch means is provided for releasably latching the handle to the drive shaft for conjoint movement of these members in their switchclosing directions. A second latch means is provided for automatically releasably latching the handle against movement in its reset direction as the handle approaches closed position. Trip means are provided for releasing the first latch means to permit the energy storage device to rotate the drive shaft in its switchopening direction and thus actuate the drive means to open the switch. The mechanism further includes means for releasing the second latch means to release the handle for movement in its reset direction, independently of the drive means, after opening of the switch. The handle is not used directly to open the switch, but, in one embodiment, can be used to actuate the trip mechanism.

Other and further objects of the invention will be apparent from the following description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation view of a load break switch equipped with a switch-operating mechanism constructed in accordance with the present invention, the switch itself being of known construction;

FIG. 2 is a side elevation view of the switch of FIG. 1;

FIG. 3 is a front elevation view, with the front wall of the housing removed, of the switch-operating mechanism for the switch of FIG. 1, with the switch in closed condition;

FIG. 4 is a plan view of the switch-operating mechanism with the switch in closed condition;

FIG. 5 is an elevation view like FIG. 3 but with the switch in open condition;

FIG. 6 is a plan view like FIG. 4 but with the switch in open condition;

FIGS. 7 and 8 are charts of the operating sequences for certain elements of the mechanism of FIGS. 1-6 for opening and closing the switch, respectively;

FIG. 9 is a detail plan view, like part of FIG. 4, of a modification permitting use of the handle for tripping the switch;

FIG. 10 is a detail elevation of the modification of FIG. 9; and

FIG. 11 is a section view taken approximately along line 11-11 in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 and 2 illustrate a load break pressure contact switch 10, having a contact mechanism of known construction, in its closed condition. Switch 10 is operated by a trip-free operating mechanism 20 mounted in a housing 19 supported on base 11 and constructed in accordance with the present invention, as described in detail hereinafter Switch 10 includes a base member 11 fabricated from a suitable insulating material. Across the top of base 11 there are mounted three

fixed contacts

21, 22 and 23. The

fixed contacts

21, 22 and 23 are provided with outwardly projecting

contact blades

21A, 22A and 23A, respectively, and each may be provided with an individual terminal lug (not shown) thus affording three input terminals for switch 10. Three are

chutes

25, 26 and 27 are mounted on

fixed contacts

21,22 and23, respectively.

Each of the fixed contacts 21-23 is one element of a pole for switch 10. Fixed

contacts

21, 22 and 23 are engageable by three

movable contacts

31, 32 and 33, respectively. Each of the movable contacts of the switch comprises a pair of contact blades, such as blades 31A and 318 for movable contact 31.

Movable contacts

31, 32 and 33 are pivotally mounted upon three electrical connector brackets 35, 36 and 37, respectively, by means of suitable pivot members such as the bolts 38.

Switch further includes an actuating bar 39 that extends transversely of the switch and that is also pivotally mounted upon the three fixed contact brackets 35-37 by means of the three bolts 38. Actuator bar 39 is connected to each of the movable contacts 31-33 by means of a connecting linkage, so that pivotal movement of bar 39 with respect to the aligned pivot pins 38 drives the movable contacts of the switch to move pivotally into and out of engagement with fixed contacts 21-23. Switch 10 is also provided with appropriate overload fuses and electrical connectors to afford a means to complete electrical connections to the movable switch contacts.

Switch 10, as thus far described, corresponds in construction to the load break pressure contact switch described and claimed in US. Pat. No. 3,213,247. The present invention is not directed to the switch structure per se, but pertains to the operating mechanism that is incorporated in the switch 10 and that is utilized to open and close the switch. The invention should not be construed as limited to the particular load break switch of US. Pat. No. 3,213,247, which is merely illustrative of a number of different forms of switch in which the invention may be incorporated.

The actuating bar 39 of switch 10 is connected to and operating rod 40 by means of a pivotal connection 41. More specifically, rod 40 has its upper end affixed to an upper yoke 45 and its lower end secured to a lower yoke 46. Lower yoke 46 is pivotally connected to an operating lever 50 that is a part of operating mechanism 20. In FIGS. 1 and 2, operating lever 50 is shown in its upper or closed-switch position with the manually operable handle 51 of the switch-operating mechanism 20 disposed at an angle of approximately 80coun terclockwise from the horizontal (FIG. 1). When the switch 10 is tripped to is open position, handle 51 pivots from the solid line position of FIG. 1 to the dash line position 51A. Opening of theswitch is effected by lever 50, which turns in a clockwise direction and pulls drive rod 40 downwardly to pivot actuating bar 39 outwardly and away from switch base 11. This pivotal movement of bar 39 simultaneously pivots the movable contacts 31-33 outwardly from the fixed contacts 21-23, to the open position 33A shown in FIG. 2, and thus opens the switch. It should be noted that the angular extent of the arcuate movement of bar 39 does not necessarily correspond to the arcuate movement of the switch contacts; in a typical instance, bar 39 may move through an arc of approxi mately 90whereas the blade contacts of the switch are pivoted only through an angle of approximately 45. However, this differential is not critical to the operation of the present invention and is a matter of design choice insofar as the construction of the switch contacts is concerned.

The number of poles in the switch 10, as well as the size of the contact elements of the switch, may be varied for different applications. However, for all switches of this general kind it is essential that the contacts separate rapidly and close rapidly in order to prevent excessive arcing, which would otherwise limit the useful contact life quite severely.

The internal construction of switch-operating mechanism 20 is best shown in FIGS. 3-6. As shown therein, the switchoperating mechanism comprises an overcenter spring drive device 52, sometimes referred to herein as a spring drive means, that is utilized to actuate the switch 10 in a quick-make quick-break operation as described more fully hereinafter. The overcenter spring drive means 52 also biases the switchoperating mechanism either to the closed position of FIGS. 3 and 4 or to the open position of FIGS. 5 and 6.

Drive means 52 includes a drive shaft 54. Shaft 54 is mounted in a bearing supported in the rear wall 56 of housing 19; housing 19 further comprises a bottom wall 55, a front wall 57, and end

walls

58 and 59. Lever 50 is freely pivotally mounted on shaft 54. Wall 59 is formed with an inwardly directed pyramidal-shaped embossure 60 having an aperture 61 through which a drive rod 62 projects. The apex of embossure 60 serves as a fulcrum for pivotal movement of drive rod 62 between the positions illustrated in FIGS. 3 and 5'. A collar 65 is freely slidably mounted on the right-hand portion of drive rod 62,just inside wall 59, and is maintained in engagement with the apex of embossure 60 by a toggle spring 53 mounted in encompassing relation to rod 62.

The left-hand end of spring 53 engages a collar 67. Collar 67 is held in fixed position upon drive rod 62 by the spring and by a pin 68 that prevents axial movement of collar 67 to the left along the drive rod as seen in FIGS. 3-6.

Drive means 52 further includes a connecting means 72 that affords an operating connection between lever 50, on the one hand, and shaft 54 on the other. Connection means 72 comprises a cam 73 that is affixed to shaft 54 for rotation with the shaft by appropriate means such as a pin 80. A pair

ofopposed follower plates

75 and 76 are rotatably mounted upon shaft 54.

Followers

75 and 76 are spanned by a pair of

pins

84 and 85, positioned for engagement by cam 73 and lever 50. Follower 76 is pivotally connected to the left-hand end of the tog glc spring drive rod 62 by a pin 88, the connection being made to a finger like extension 89 of follower 76. As best shown in FIG. 4, the end of drive rod 62 is bifurcated to receive extension 89.

Mechanism 20, particularly as illustrated in FIGS. 3-6, is intended for use with a rather low amperage switch, a switch in the lower or middle range of those normally utilized in heavy-duty service entrance requirements and similar applications. To afford the necessary operating power for toggle action of the switch-operating mechanism in a high-amperage switch, mechanism 20 may be provided with a second overcenter spring drive, including a drive rod and spring, that is a substantial duplicate of drive means 52 as described above. The second overcenter spring drive means may be connected to operating lever 50 in tandem with drive means 52, as generally described in the aforesaid copending application Ser. No. 667,044. If necessary, a third or fourth overcenter spring drive can be added to mechanism 20 to accommodate even larger switches. It is thus seen that the switch-operating mechanism provides for a modular construction to permit utilization of duplicate parts in mechanisms that can accommodate switches operable over a wide range of load currents. By way of example, mechanism 20 can be increased in size or decreased in size, as desired, to provide effective operation for switches used over a range as wide as 400 to 6000 amperes.

As thus far described, mechanism 20 is basically similar to the corresponding mechanism described in the aforesaid copending application Ser. No. 667,044; however, some modifications have been made. Thus, a counterweight 91 is incorporated in device 52, being affixed to shaft 54 for rotation therewith. An auxiliary switch drive lever 92, having a cam extension 93 that engages a cam follower roller 94, is rotatably mounted on shaft 54 and connected to lever 50. Roller 94 is mounted on the actuating arm 95 of an auxiliary switch 96 mounted to the rear wall 56 of housing 19. The electrical circuit for switch 96 is described hereinafter.

Switch-operating mechanism 20 includes an actuating mechanism 100 that embodies the principal features of the present invention. Actuating mechanism 100 includes a solenoid 101 that is mounted externally of wall 58, the solenoid including a downwardly extending armature 102. The lower end of armature 102 is pivotally connected to one end of a lever 103. Lever 103 extends through an aperture in wall 58 and the inner end of the lever is pivotally connected, by a pin 104, to a bracket 105 that is mounted on the bottom 55 of housing 19. Within the housing, an intermediate point on lever 103 is connected by a pin 106 to a trip link 107. Trip link 107 is guided for vertical movement, parallel to wall 58, by a guide bracket 108 having a horizontal portion 111. The upper end of trip link 107 terminates in a lug 109 located above the bracket portion 1 11.

The operating handle 51 is affixed to a handle shaft 112 that isjournaled in and supported by a bearing 113 mounted in the front wall 57 of housing 19. Shaft 112 is coaxially aligned with shaft 54 and includes a sleeve portion that projects inwardly of wall 57 and encompasses a reduced diameter section 54A at the end of shaft 54 adjacent front wall 57. Thus,

shafts

54 and 112 are coaxially aligned with each other but are free to rotate relative to each other.

A close lever 115 is mounted upon shaft 112 for rotation therewith. Close lever 115 carries a pivot pin 118 upon which a trip latch 119 is pivotally mounted. A pin 121 is mounted on the extreme left-hand of trip latch 119, as viewed in FIGS. 3 and 4. Trip latch 119 is positioned to be engaged by lug 109 on the upper end of trip link 107, during operation of mechanism to open switch 10, as described more fully hereinafter. Pin 121 is positioned to be engaged by a manual trip cam 122. Cam 122 is affixed to the inner end of a trip lever shaft 123 that is journaled in and supported by a bearing 125 mounted in the front wall 57 of housing 19. Shaft 123 projects externally of housing wall 57 and the outer end of the shaft has a manual trip lever 126 affixed thereto.

When operating mechanism 20 is in its closed condition, as shown in FIGS. 3 and 4, a pin 127 mounted on trip latch 119 extends across close lever 115. Pin 127 is engaged by a spring 128 that is anchored to the trip latch pivot pin 118. Still referring to the closed condition of the mechanism, FIGS. 3 and 4, a lug 129 on trip latch 119 is seen to engage a lug 131 on an opening spring lever 132. Lever 132 is mounted upon a hub 133 that is affixed to shaft 54 for rotation with the shaft by appropriate means such as a roll pin 134 (FIG. 4). Lever 132 is a crank having two projecting ends, one of which comprises lug 131. The other end of lever 132 is pivotally connected, by appropriate means such as a pin 135, to an opening spring guide rod 136. There is a lug 146 on the bottom oflever 132.

An opening spring 137 is mounted in encompassing relation to rod 136. The left-hand end of spring 137 engages a washer 138 that is held in position on the rod by action of the spring and by a stop pin 139. At the other end of spring 137, the spring engages another washer 140 that contacts the apexial portion of a pyramidal embossure 139 in the end wall 59 on the operating mechanism housing. Embossure 139 is provided with an opening through which rod 136 projects. Spring 137 constitutes an energy storage device for actuating drive shaft 54in opening switch 10, as described hereinafter.

Actuating mechanism 100 further comprises a close latch 141 that is pivotally mounted upon a short pivot pin or shaft 142 projecting inwardly from the front wall 57 of the operating mechanism housing. With the operating mechanism in its closed position (FIGS. 3 and 4), a lug 143 on the upper end of close latch 141 engages the trip latch pivot pin 118 that is mounted upon close lever 115. The lower end of close latch 141 comprises an extension 145 positioned to be engaged bya cam surface 150 on the lower edge of lever 132 during operation of the mechanism to open the switch, as described more fully hereinafter. The lower part of close latch 141 is engaged by a close latch spring 147, which is a leaf spring having one end mounted upon the bottom 55 of the operating mechanism housing and extending upwardly therefrom particularly as shown in FIGS. 3 and 5.

In considering operation of mechanism 20, and particularly its actuating mechanism 100, it may be assumed initially that the switch is in closed condition, with the elements of the operating mechanism in the latched condition illustrated in FIGS. 3 and 4. Auxiliary switch 96 is connected in series in the operating circuit for trip solenoid 101. Switch 96 is in its normal closed condition; accordingly, it is possible to complete an electrical circuit to solenoid 101 to initiate opening of load break switch 10.

When trip solenoid 101 is energized, its armature 102 is pulled upwardly (FIGS. 1 and 3), pivoting lever 103 in a clockwise direction about its pivotal mounting at pin 104. This movement of lever 103 pushes trip link 107 upwardly and drives lug 109 into engagement with the end portion of trip latch 119. Consequently, trip latch 119 is pivoted in a clockwise direction about its pivot pin 118.

As trip latch 119 begins to rotate in a clockwise direction, lug 129 on the trip latch is released from its engagement with lug 131 on opening spring lever 132. When lug 129 clears lug 131, opening spring lever 132 begins to rotate in a clockwise direction in response to the force exerted upon it by the compressed opening spring 137. Stated differently, upon release of the engagement between lugs I29 and 131 (FIG. 3), the latch means that has previously latched handle shaft 112 to drive shaft 54 and that has held opening spring 137 in its compressed condition is released; consequently, the spring expands, driving opening lever 132 and shaft 54 in a clockwise direction.

As shaft 54 begins to rotate in a clockwise direction, from the position illustrated in FIG. 3, cam 73, which is mounted on shaft 54, engages

pin spanning followers

75 and 76. Consequently,

followers

75 and 76 begin to rotate in a clockwise direction. The rotational movement of

followers

75 and 76 compresses toggle spring 53, due to the connection between follower 76 and toggle spring drive rod 62. At the same time, the rotational movement of

followers

75 and 76 pivots drive rod 62 in a counterclockwise direction about the fulcrum of drive rod 62 at embossure 60. That is, drive rod 62 is driven axially to the right, from the position shown in FIG. 3, while at the same time the left-hand end of drive rod 62 is forced downwardly in response to the clockwise rotation of

followers

75 and 76.

With continuing movement of drive rod 62 and spring 53, as described above, the left-hand end of the drive rod passes the horizontal centerline 151 for the mechanism. Thereafter, with continued pivotal movement of rod 62 and spring 53, spring 53 expands, applying a driving force to drive the mechanism toward the switch open position of FIGS. 5 and 6. The resulting continued clockwise rotation of

followers

75 and 76 brings pin 84 into engagement with cam 73. Accordingly, the clockwise rotation of cam 73 and shaft 54 is continued, under the impetus afforded by the action of operating spring 53, rapidly driving the switch-operating mechanism to the open condition illustrated in FIGS. 5 and 6.

During the opening movement of mechanism 20, as described above, operating lever 50 is engaged by pin 84 between

followers

75, 76 and is rotated in clockwise direction to the position shown in FIG. 5. Consequently, rod 40 is pulled downwardly and to the right to the switch openposition illustrated in FIG. 5. It is this movement of rod 40 that opens load break switch 10. Counterweight 91, on shaft 54, smooths the action of the driving members, absorbing energy during slack periods and delivering energy back into the linkages when loads are picked up. The free end of counterweight 91 also engages the upper edge of housing wall 56 (FIGS. 5 and 6) to absorb residual energy of spring 53 that could otherwise cause impact damage to the drive pins and mating surfaces in the mechanism.

As opening spring lever 132 rotates in a clockwise direction, as described above, its cam edge 150 engages the lower extension portion 145 of close latch 141. This starts close latch 141 rotating in a clockwise direction about its pivot 142, from the position illustrated in FIG. 3. The clockwise rotation of close latch 141 releases the close latch from engagement with pin 118 on close lever 115. This releases the handle shaft 112, to which close lever is affixed, for rotation in its clockwise reset direction, independently of drive means 52.

With continuing clockwise rotation of opening spring lever 132, responsive to the force applied by expansion of opening spring 137, the lug 146 on lever 132 ultimately engages the lower surface of close lever 115. Thus, the residual energy of opening spring 137 is utilized to initiate rotation of close lever 115 in a clockwise direction. Since close lever 115 is affixed to shaft 112, the resulting clockwise rotation of shaft 112 starts handle 51, which is affixed to shaft 112, to rotating in a clockwise or reset direction. Only a limited initial impetus is required or desired; once the inertia of handle 51 is overcome, it continues the reset rotation of shaft 112. The handle falls freely and gently to the position 51A illustrated in FIG. 1. Thus, there is little or no possibility of injury to anyone who may chance to be near switch 10 when the switch is tripped electrically from some remote location.

Auxiliary switch drive lever 92 is connected to and rotates with operating lever 50. Lever 92 engages roller 94 on auxiliary switch 96 to open the trip coil circuit and prevent useless energization of solenoid 101 when lever 50 is in its switch open position.

Electrical tripping of switch operating mechanism 20, and particularly its actuating mechanism 100, can be duplicated manually. For manual trip operation, with the mechanism in the closed position illustrated in FIGS. 3 and 4, trip lever 126 is pushed downwardly, rotating trip lever shaft 123 in a clockwise direction. The clockwise rotation of shaft 123 imparts a similar rotation to trip cam 122. As trip cam 122 rotates clockwise from the position illustrated in FIG. 3, it engages pin 121 on trip latch 119. As a consequence, trip latch 119 is pivoted in a clockwise direction to release its lug 129 from engagement with lug 131 on opening spring lever 132, initiating opening of the switch. Since the switch-opening operation is powered by

springs

137 and 53 and is controlled completely by the operating mechanism itself, the opening of switch 10 proceeds as described above for electrical actuatron.

When switch 10 is open, switch handle 51 is in a generally lowered position as indicated by dash outline 51A in FIGS. 1 and 6. The positions of the individual elements of the switchoperating mechanism and of actuating mechanism 100 are as shown in FIGS. 5 and 6. To close the switch, handle 51 is first turned though a short arc, in its clockwise reset direction, to a reset position 518 (FIG. 1), which, in this particular switch mechanism, is at an angle of approximately 46from the horizontal.

The limited additional clockwise rotation of handle shaft 112 that is effected by rotation of handle 51 to its reset position, as described above, moves close lever 115 clockwise from the position shown in FIG. 5. The upper end of close lever 115 engages pin 127 on trip latch 119 and pivots the trip latch in a clockwise direction about its pivot 118. At the same time, trip latch 119 moves downwardly and to the right from the position shown in FIG. 5, since the trip latch pivot 118 is mounted on close lever 115.

This movement of trip latch 119 downwardly and to the right from the position illustrated in FIG. 5 brings the trip latch lug 129 into engagement with lug 131 on opening spring lever 132. When the manual operating handle 51 is released, at the reset position, trip latch spring 128 imparts a quiet limited counterclockwise rotation to trip latch 119 and engages trip latch lug 129 firmly with opening spring lever lug 131. Moreover, the trip latch spring maintains lugs 129 and 131 in engagement during closing movement of the switch operating mechanism. Thus, the latch means comprising lugs 129 and 131 releasably latches handle 51 to drive shaft 54 for conjoint movement of the handle and the drive shaft in their counterclockwise switch-closing directions.

AFter the initial clockwise reset movement of handle 51, as described above, the handle is rotated manually, counterclockwise, driving shaft 112 with it. Because close lever 115 is latched to opening spring lever 132 by trip latch 119, and because opening spring lever 132 is pinned to shaft 54, shaft 54 is rotated counterclockwise with shaft 112. The counterclockwise rotation of shaft 54 pivots cam 73 counterclockwise from the position illustrated in FIG. 5 and brings the cam into engagement with pin 84 spanning

followers

75 and 76. Accordingly,

followers

75 and 76 also are turned in a counterclockwise direction.

As

followers

75 and 76 turn counterclockwise, operating spring drive rod 62 is driven upwardly and to the right, from the position of FIGS. 5 and 6, compressing toggle operating spring 53. The point of maximum compression is reached when the Ieft-hand end of drive rod 62 crosses center line 151. Once this point is passed, toggle spring 53 expands, continuing the counterclockwise rotation of

followers

75 and 76. This rotation of the followers drives pin 85 into engagement with cam 73 to continue the counterclockwise rotation of drive shaft 54. Pin 85 engages the lower surface of operation lever 50 and drives lever 50 in a counterclockwise direction to the closed position illustrated in FIG. 3. As operating lever 50 rotates counterclockwise, it drives rod 40 upwardly and to the left and closes switch 10.

As shaft 54 rotates counterclockwise in closing of the switch, as described above, opening spring lever 132 rotates with the shaft, carrying trip latch 119 along with it. Furthermore, the counterclockwise rotation of opening spring lever 132 compresses opening spring 137 by pushing rod 136 upwardly and to the right from the position shown in FIG. 5 to that illustrated in Flg. 3. The counterclockwise rotation of trip latch 119 and close lever 115 continues with the continuing counterclockwise movement of handle 51. Indeed, until toggle spring 53 passes its center point, the entire impetus toward closing movement of the mechanism and the switch is pro vided by rotation of the handle 51, the force applied by the operating acting to compress both of the

springs

53 and 137.

As opening spring lever 132 moves away from its engagement with close latch 141 (FIG, 5) close latch 141 rotates in a counterclockwise direction about its pivot 142 in response to the biasing force exerted by close latch spring 147. Near the end of the counterclockwise rotation of close lever 115, pin 118 passes over and engages lug 143 on lever 141, which is pivotally mounted on the sidewall 57 of housing 19. Lug 143 and pin 118 afford a second latch means that automatically releasably latches handle 51 against movement in its reset direction as the handle approaches its fully closed position, illustrated in FIG. 3.

As trip latch 119 nears the end ofits counterclockwise rotation, pin 121 on the trip latch engages manual trip cam 122, pivoting manual trip cam 122 and trip lever 126 back to the closed position of FIG. 3. Lug 129 on trip latch 119 remains engaged with lug 131 on operating spring lever 132 so that actuating mechanism ends up in the completely latched con dition illustrated in FIGS. 3 and 4. As the closed and latched position is reached, auxiliary switch drive lever 92, driven by and moving together with lever 50, releases roller 94 and closes auxiliary switch 96. Thus, the mechanism reaches its closed position conditioned for either manual or electrical trip operations.

FIGS. 7 and 8 illustrate the sequence of operations for the principal components of mechanism 20 on switch opening and switch closing, respectively. These operational charts are based on rotational positions of the operating elements, and not on time. Thus, in the switch-opening operation, FIG. 7, the expansion of drive spring 53 takes considerably less time than compression of that spring. The same is true of the operation of the toggle drive spring 53 in the switch-closing operation. FIG. 8.

Operating mechanism 20 assures both quick-make nd quick-break operation for switch 10, minimizing arcing and consequent damage to the load break switch. When tripped, switch 10 snaps open, in response to the combination of forces exerted by opening spring 137 and toggle spring 53, but handle 51 is released only after the switch has opened. The handle falls gently by gravity to position 51A and cannot endanger personnel in the vicinity. The initial impetus to handle 51 is limited to the residual energy of spring 137 when that spring is nearing full expansion and hence presents no danger. Counterweight 91 stores the initial energy from opening spring 137 to assure actuation of drive spring 53 past its center position.

The closing operation (FIG. 8) is arranged so that the toggle drive spring 53 goes overcentcr center just before opening spring 137 is latched, effectively rendering the mechanism teaseproof. That is, the mechanism has no dead" range in which it could hang up with the switch contacts neither fully open nor fully closed.

It will be recognized that other forms of energy storage can be substituted for spring 137. Thus, a torsion spring can be readily utilized for this purpose. In large switches, if the manual effort required to close the switch becomes excessive, a ratchet may be utilized to afford a mechanical advantage in closing, with plural movements of the handle at reduced force being employed to close the switch.

FIGS. 9,10 and 11 illustrate a modification of the present invention that makes it possible to use handle 51 to actuate the trip apparatus of operating mechanism 20, although the handle still does not provide a direct drive for opening the switch in normal operation. In these figures, reference numerals for corresponding parts remain unchanged from those employed in the embodiment described above.

In the modification shown in FIGS. 9-11, the mounting for handle 51 is changed to some extent. The handle is affixed to a hub 230 having an axial slot for receiving the projecting portion of shaft 112. The inner end of hub 230 is provided with a pair of opposed arcuate slots 232, each slightly more than 45in length. The inner end of hub 230 is brazed or otherwise fixedly mounted to a cam plate 231 that closes off the inner ends of the slots 232. Hub 230 is mounted upon shaft 112 by means of a pin 233 driven through a transverse opening in the shaft and projecting through both of the slots 232. Pin 233 serves to retain hub 230 on shaft 112 but permits relative arcuate movement of the hub 230 with respect to shaft 112 through an angle of about 45.

Cam 231 has a flat edge surface 234 that is aligned with a flat surface 235 on a cam follower lever 236. Lever 236 is pivotally mounted upon a pin or shaft 238 that is in turn mounted to the front wall 57 of the switch-operating mechanism housing. Surface 234 clears surface 235, allowing cam 236 to pivot to its maximum counterclockwise position when handle 51 is in closed position (FIG. 10).

In the construction illustrated in FIGS. 911, the manual trip lever 126 of the previous embodiment is replaced by a smaller trip lever 226 having a projection 227 positioned to be engaged by a portion 237 of lever 236. As before, manual trip lever 226 is mounted upon the shaft 123 that carries the manual trip cam 122 (FIG. 9). Thus, cam 231, lever 236, and lever 226 afford a linkage between handle 51 and the trip means, comprising cam 122, for the switch-operating mechanism. This internal apparatus of operating mechanism 20, including the alignment of main shaft 54 and handle shaft 112, remains essentially unchanged.

In FIGS. 911, the operating mechanism is shown in the switch-closed condition. When it is desired to actuate the switch to open condition, handle 51 is pivoted in a clockwise direction, rotating hub 230 clockwise. Rotation of hub 230 causes a corresponding rotation of cam 231, engaging its cam surface 234 with the cam follower surface 235 of lever 236. Consequently, lever 236 rotates in a clockwise direction, engaging trip lever 226 and pivoting the trip lever toward its tripped position 226A. The clockwise rotation of lever 226 to position 226A causes a corresponding rotation of its shaft 123 and drives the manual trip cam 122 from its initial closed position (FIG, 3) to its tripped position (FIG. 5). This trips the switch in the same manner as described in detail above.

When the switch is tripped manually by operation of handle 51 as described above, latch 129 (FIG. 3) is disengaged from lever 150, allowing spring 137 to drive follower 75 and operating lever 50 to the switch-open position. When the switch open position is reached, handle 51 is freed to move to its switch open position in the manner described above. As before, the handle is recoupled to lever 150 when the handle is moved to its reset position.

Indicator markings, such as the closed indicator 241 and the Open indicator 242, can be used to afford a precise indication of the operating condition of the switch in accordance with the position of pin 233, as shown in FIGS. and 11. Pin 233 can point to indicator 241, as in FIGS. 10 and 11, only when the switch is fully closed and latched. It points to indicator 242, at the right-hand end thereof, when the switch is open.

Handle 51, nevertheless, continues to serve as a reliable indicator of the switchoperating condition. The handle position shown in FIG, 10 is possible only when the switch is closed and latched. And the handle moves clockwise to position 51A (FIG. 1) whenever the switch opens. Thus the handle position affords a basic indication of the switch position visible from a substantial distance.

The specific embodiments of the invention illustrated and described herein each afford a manually operable mechanism with a spring trip attachment. It will be apparent, however, that the spring trip can be incorporated in the motor-driven mechanism described in the aforesaid copending application SEr. No. 667,044 to provide quick-make and quick-break blade action with a spring loaded closed position. Tripping of the switch, in the motor-driven arrangement, would require only a very short time, ofthe order of one-tenth second.

When the switch is closed, the opening spring 137 and the switch mechanism are effectively disengaged from handle 51, leaving spring 137 free to actuate the switch to its fully open position. Because handle 51 is operably connected in the switch-opening direction only, and cannot be moved to its open" position without fully opening the switch, the handle can be used as a positive interlocking'means to block access to the switch, and particularly the fuses, unless the switch is open. Installations of these switches normally have a front wall, with a cover door for each switch, through which the switch handles project; operator safety is assured by inter locking the door with the handle so that the switch cannot be closed when the door is open and the door cannot be opened unless the switch is open.

With the modification of FIGS. 9-11, actuation of the switch from its open condition to its closed condition is effected by means of handle 51 as described above, without change.

I claim:

1. A trip-free operating mechanism for a load break switch of the kind comprising a fixed contact engageable by a movable contact operable between a full-closed position and a fullopen position, said operating mechanism comprising:

a drive shaft rotatable in opposed switch-opening and switch-closing directions between closed and open positions;

overcenter spring drive means interconnecting said drive shaft and said movable contact and actuatable in two opposed directions across a center point in response to initial rotation of-said drive shaft through a given minimum angle, for quickly driving said movable switch contact and said drive shaft to their respective open and closed positions;

an operating handle rotatable in opposed switch-closing and reset directions between an open position and a closed position;

a switch-opening energy storage device connected to said drive shaft actuating means for charging said energy storage device and for rotating said drive shaft through said minimum angle in said switch-closing direction to actuate said drive means and close said switch, in response to rotation of said handle through a given minimum arc in its switchclosing direction;

first latch means, in said actuating means, for releasably latching said handle to said drive shaft for conjoint movement of said handle and said drive shaft in their respective switch-closing directions;

second latch means, in said actuating means, for automatically releasably latching said handle against substantial movement in said reset direction as said handle approaches its closed position;

trip means for releasing said first latch means;

said energy storage device being effective to rotate said drive shaft in its switch-opening direction and actuate said drive means to open the switch upon release of said first latch means;

and means for releasing said second latch means to permit movement of said handle in its reset direction, independently of operation of said drive means, after opening of said switch.

2. A trip-free operating mechanism for a load break switch,

according to claim 1, in which said energy storage device is a spring.

3. A trip-free operating mechanism for a load break switch, according to claim 1, in which said trip means comprises an electrically operated device that may be energized from a remote location.

4. A trip-free operating mechanism for a load break switch, according to claim 3, including a second trip means, manually actuatable, that is independent of the electrically operated trip means.

5. A trip'free operating mechanism for a load break switch, according to claim 4, in which said second trip means includes a linkage for actuating said second trip means in response to limited movement of said handle, in said reset direction, from its closed position.

6. A trip-free operating mechanism for a load break switch, according to claim 5, in which said handle is mounted on a handle shaft aligned coaxially with said drive shaft but rotatable relative thereto, and in which said switch-closing and reset directions for said handle coincide with said switch-closing and switch'opening directions, respectively, for said drive shaft, the mounting of said handle on said handle shaft affording angular slack of about 45to enable actuation of said second trip means by said handle when latched by said second latch means.

7. A trip-free operating mechanism for a load break switch, according to claim 1, in which said first latch means is actuated by movement of said handle, in said reset direction, from a tripped position to a reset position.

8, A trip-free operating mechanism for a load break switch, according to claim 1, in which said handle is mounted on a handle shaft aligned coaxially with said drive shaft but rotatable relative thereto, and in which said switch-closing and reset directions for said handle coincide with said switch-closing and switch-opening directions, respectively, for said drive shaft.

9. A trip-free operating mechanism for a load break switch, according to claim 1, in which said second latch means is actuated to latched condition immediately after said drive means passes its center point in closing said switch.

Claims

1. A trip-free operating mechanism for a load break switch of the kind comprising a fixed contact engageable by a movable contact operable between a full-closed position and a full-open position, said operating mechanism comprising: a drive shaft rotatable in opposed switch-opening and switchclosing directions between closed and open positions; overcenter spring drive means interconnecting said drive shaft and said movable contact and actuatable in two opposed directions across a center point in response to initial rotation of said drive shaft through a given minimum angle, for quickly driving said movable switch contact and said drive shaft to their respective open and closed positions; an operating handle rotatable in opposed switch-closing and reset directions between an open position and a closed position; a switch-opening energy storage device connected to said drive shaft actuating means for charging said energy storage device and for rotating said drive shaft through said minimum angle in said switch-closing direction to actuate said drive means and close said switch, in response to rotation of said handle through a given minimum arc in its switch-closing direction; first latch means, in said actuating means, for releasably latching said handle to said drive shaft for conjoint movement of said handle and said drive shaft in their respective switchclosing directions; second latch means, in said actuating means, for automatically releasably latching said handle against substantial movement in said reset direction as said handle approaches its closed position; trip means for releasing said first latch means; said energy storage device being effective to rotate said drive shaft in its switch-opening direction and actuate said drive means to open the switch upon release of said first latch means; and means for releasing said second latch means to permit movement of said handle in its reset direction, independently of operation of said drive means, after opening of said switch.

2. A trip-free operating mechanism for a load break switch, according to claim 1, in which said energy storage device is a spring.

5. A trip-free operating mechanism for a load break sWitch, according to claim 4, in which said second trip means includes a linkage for actuating said second trip means in response to limited movement of said handle, in said reset direction, from its closed position.

6. A trip-free operating mechanism for a load break switch, according to claim 5, in which said handle is mounted on a handle shaft aligned coaxially with said drive shaft but rotatable relative thereto, and in which said switch-closing and reset directions for said handle coincide with said switch-closing and switch-opening directions, respectively, for said drive shaft, the mounting of said handle on said handle shaft affording angular slack of about 45*to enable actuation of said second trip means by said handle when latched by said second latch means.

8. A trip-free operating mechanism for a load break switch, according to claim 1, in which said handle is mounted on a handle shaft aligned coaxially with said drive shaft but rotatable relative thereto, and in which said switch-closing and reset directions for said handle coincide with said switch-closing and switch-opening directions, respectively, for said drive shaft.