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Publication numberUS3193632 A
Publication typeGrant
Publication dateJul 6, 1965
Filing dateJun 20, 1961
Priority dateJun 20, 1961
Publication numberUS 3193632 A, US 3193632A, US-A-3193632, US3193632 A, US3193632A
InventorsSprague Stephen B
Original AssigneeMc Graw Edison Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pry-off latch for disconnect switch
US 3193632 A
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Description  (OCR text may contain errors)

y 6, 1965 s. B. SPRAGUE 3,193,632

FRY-OFF LATCH FOR DISCONNECT SWITCH Filed June 20, 1961 IN VEN TOR.

STfPHE N B. SPRAGl/E @143 24/23/33 ATTORNEY United States Patent This invention relates to electric switches and more particularly to disconnect switches adapted to be operated by a hook stick.

Disconnect switches are usually mounted on elevated structures for safety reasons. They are operated, from the ground, by an insulated operator or hook stick which cooperates with portions of the switch in the opening and closing operations. Disconnect switches must be capable of safely carrying high currents and also overloads due to momentary faults. In order to assure continuity of the circuit and to guard against non-intentional opening of the switch latching means is provided to maintain the switch in the closed circuit position.

Disconnect switches must be capable of being operated under adverse weather conditions. Ice formation has been an acute problem. The switch must be capable of being opened even though encumbered by the heavy ice coating. Heretofore, disconnect switches have had separate latches and pry-off means for breaking the ice coating requiring separate operations. The latch means and operating means heretofore employed have had a large number of parts which, due to the ice coating, made opening of the switch difiicult. It is an object of this invention to improve the reliability of disconnect switches under severe weather conditions.

It is yet another object of the invention to provide a novel disconnect switch capable of being opened with a single continuous motion.

It is another object of this invention to provide an improved hook operated disconnect switch with increased ease of opening under icing conditions.

These and other objects and advantages are achieved in an illustrative embodiment of the invention described in detail below. In the illustrative embodiment of the invention, a hook-operated disconnect switch is provided having a movable switch blade and a companion contact. A combined latch and pry-off member is mounted on the switch blade for engagement with a portion of the companion contact structure. The mounting means for the combined member provides for the pivotal movement of the member in the plane of the switch blade and for the movement of the member along the longitudinal axis of the blade within said plane. Biasing means mounted on the blade urges the member in the latch retaining direction when the switch is closed.

For a better understanding of the invention, reference is made to the following description taken in conjunction with the accompanying drawings depicting an illustrative embodiment of the invention in which:

FIG. 1 is a perspective view of a disconnect switch embodying various aspects of the invention;

FIG. 2 is a fragmentary sectional view of a portion of the latch structure as viewed from the horizontal plane designated 22 in FIG. 1, drawn to larger scale;

Referring to the drawings, the disconnect switch It) "ice comprises a base channel 11 upon which are mounted a pair of insulator stacks 12, 14. The switch It is shown in FIG. 1 with the channel 11 mounted vertical. The switch blade 16 is pivoted to swing in the vertical plane about pin 18 carried by bracket 20 secured to the top of the insulator stack 14. Bracket 20 has bolt holes 22 for attaching the clamp of a transmission line conductor.

Highly conductive contact inserts 24 are secured to the legs 26, 28 of the switch blade 16. Legs 26, 28 are spaced apart at one end by the bracket 20 and connected together intermediate their ends by a spacer pin 30.

Contact bracket 32 is carried by insulator stack 12. Contacts 34 are formed on one end of the member 32 in the form of a pair of resilient separated fingers. Blade contacts 24 engage companion contacts 34 in the closed position of the switch. Bracket 32 is provided with bolt holes 36 for a cable clamp, to connect the other transmission line conductor to the swtich.

A combined latch and pry-cit member 40 is provided with an opening 42 for engagement by the hook stick 43 shown in phantom in FIGS. 4, 5 and 6. The combined pry-off member and latch 40 is mounted on the switch blade 16 by a pin 44 through the switch blade legs 26, 28. The inturned ends 45 of the legs 26, 28 center the member 40 with respect to the longitudinal axis of the blade 16. Latch 40 has a slot 46 which allows the latch to be moved along the switch blade 16 relative to pin 44 as well as allowing the latch to pivot about pin 44 in the plane of the axis of the blade. Slot 46 may be described as having a forward end 46a and rearward end 4612.

Referring to FIG. 2, catch 50 is mounted by bolt 52 on the companion contact bracket 32 adjacent the upstanding separated contact legs 34. The catch may be generally described as having the form of a truncated cone 54 on a cylindrical base 56 of smaller diameter. The cone has a top surface 58, inclined sides 60, lower peripheral edge 62 andan overhang 64 between the edge 62 and the base 56.

Latch 40 has an arm 66 adapted to engage the overhang 64 of the catch 50 when the switch is closed. The combined member 40 is resiliently urged into engagement with the catch 50 by tension spring 68. One end of spring 68 engages spacer pin 36 and the other end of the spring engages aperture 70 in leg 72 of member 40. Latch 40 does not form a significant part of the current path in the switch. Stop pin 74 is carried by the latch 49 and is engageable with the edge of switch blade 16 remote from bracket 32 when the switch is either being closed or opened as will be described in greater detail below.

The mode of operation of the illustrative embodiment will be more readily understood if the description is begun with the switch 10 in the closed position shown in FIG, 1. In the closed position the catch 50 is engaged by the combined member 40 and the resilient cont-act fingers 34 press against the contacts 24 carried by the switch .blade 16. Latch member 40 is held against the catch 50 by the spring means 68. Spring 68 has moved the latch downwardly, in FIG. 3, until the end 46a of the slot almost contact-s pin 44. Leg 66 of the latch 40 is hooked under the overhang 64 of the stop 50. In this position, catch 56 is firmly engaged by the latch member 40 since spring 68 acts along a line which passes through the center of the pivot pin 44. There is no component of the latching force present which would tend to drive the latch member 4% to the open position.

When it is desired to open the switch 10 a hook stick 43 is engaged in the opening 42 in the latch member 40. When the hook stick is pulled downwardly, as viewed in FIG. 1, the initial reaction of the latch 40 is to pivot clockwise about the pin 44 as viewed in FIG, 3 to the position shown in phantom FIG. 4. The initial movement of the latch about the pivot pin 44 causes the leg 66 to disengage the overhang 64 of the catchSt). Continued movement of the latch 49 by the hook stick'43 brings leg 72 into contact with the top surface 58 of the catch 50. This is illustrated in phantom in FIG. 4. Continued application of opening thrust by the hook stick forces the'leg 7-2 to push against the catch top 58 prying the blade 16 away from the closed position and causing separation of the contacts. The movement of the latch '46 which drives the leg '72. against the catch 53 may be described as a'pry-off operation. The leverage arrangement of the respective'lcverarms formed by the portions latch member 40 on opposite side of the pivot pin 44 is such that an effective multiplication of the separating effort is achieved. This prying effort has been found sufficient to break ice coatings formed .on the switch blade and contacts. Continued pivotal movement of the latch 49 about the pin 44 brings the stop 74 into contact with the upper'surfaceof the blade 16 as viewed in FIG. 5 'at which time continued pivotal movement of the latch 49 is arrested by the coaction of the pin. 74.

ing movement relative thereto, said latch member having a'lat-ch portion and a pry-off portion, catch means mounted on said contact means and having latch engaging means for engagement by said latch portion when said switch is closed and said lat-ch member moved in an engaging direction, the pry-off portion o-fsaid latch member engaging said catch means when said latch member is moved in a disengaging direction'to force said switchblade means out of engagement with said contact means.

2 A hook-operated disconnect switch comprising astationary contact annd a switchblade mounted in spaced relation from said stationary contact for movement into and out of resilient engagement therewith, said engagement establishing frictional forces in said members normally resisting the separation thereof, a unitary pry-off latch member mounted on said Switchblade for limited pivotal and sliding movement in the plane thereof, said latch member having a latch portion and a pry-off portion, a catch member having latch engaging means mounted on said stationary contact for engagement by said latch portion when saidswitch is closed and said latch 7 member is rotated in an engaging direction, biasing means last described, to the closed position shown in the drawings'by the use of the hook stick 43. When the switch is at rest in the open position the spring 68 causes the combined member 40 to pivot' on pin 44 on the blade until the pin 74 bears against the blade 16. When the hook stick 43 is used to drive the switch closed the stop 74 locks the lat-ch 40 against pivotal movement relative to the blade during the closing operation andthe latch 40 and blade 16 then move as a position. As the switch bladepivot-s about pin '18, the contact-s 34, 24 engage. Also, the end of the arm 66 of the latch 40 engages the inclined side 60 of the catch .50 at the start of the latching operation. Theapplication of the closing force through the hook stick 43 to the latch 40 causes the latch 40 to slide forward along the longitudinal axis of the catch 50. Stop pin 74 slides unit toward the closed forurginglsaid latch portion in the catch engaging direction, said lat-ch member engagingsaid catch in the closed position of said switch and being held :thereagainst by said biasing means, said pry-off portion of said 'latch member engaging said catch member when said latch member is pivoted in the disengaging direction to force said switchblade to move against said frictional forces and out of engagement withsaid stationary contact.

3. Aihook-operated disconnect switch com-prising a stationary cont-act and 'a switchblade mounted in' spaced relation from said stationary contact for movement into and out of resilient engagement with said stationary contact, said engagement establishing frictional forces in said members normally resisting the separation thereof, a unitary pry-off latch member mounted for limited movement on said switchblade and. having a hook-engaegable portion, said latch member having a latch portion and a pry-off portion, a catch member mounted on said stationary contact for overlapping engagement bysaid latch along the surface of the blade 16 and prevents the latch 1 member 49 from pivoting as arm'66 slides along the side 60 of the catch 54) (see FIG. 6). When the end of the arm 66 snaps over the edge 62 of the catch 50 the leg engages the overhang 64 and the latch snapsback along the longitudinal axis of the blade 16 to the latched position under the force of spring 68 (FIG. 3).

The combined lat-ch member 40 thus incorporates a latching function as well as aunitary pry-off mechanism. The described apparatus permits the opening or closing operation to be performed .by a single, continu ous push or pull, on the member 40. The pin-and-slot lost motion connection between the combined member 40 and' blade 16 allows the latch 40 to engage the catch 50 with a minimum numberlof moving parts, and stop pin 74 cooperates with the edge of switch blade 16 to provide for limited swing of latch member'4tl relative to the switch blade and to form a drive connection to the blade at both 'arcuate'limits of the swing for opening and closing the ing frictional forces in said members normally resisting the separation thereof, a unitary. pry-off latchmember mounted on said switchblade means for pivotal and'slidsaid stationary contact means, said engagement establish portion when said switch is closed, said mounting means also providing for relative sliding movement between said latch member and said switchblade in the direction of said overlapping engagement, resilient means urging said latch portion in an overlapping direction,.said pry-off port-ion cooperatively engaging said catch member when said latch member is pivoted in the disengaging direction to force said switchblade out of engagement with said stationary contact.

. 4. A hook-operated disconnect switch comprising a stationary contact :and'a switchblade mounted in spaced relation from said stationary contact for movement into and out-of resilient engagementwith said stationary contact, said engagement establishing frictional forces in said members normally resisting the separation thereof, a unitary pry-off latch member having a hook-engageable portion and being'mounted on said switchblade for pivotal and sliding movement relative thereto, said latch member having a latch portion on one side of said pivotal axis and a pry-off portion on theother side thereof, a catch member'mounted on said stationary contact for engagement by said latch portion when said switch is closed, a stop on said latch member for limiting the movement there-of relative to said switchblade in the catch- ,engaging direction, spring means'for urging said latch'portion in the catch engaging direction, said latch member engaging said catch in the closed position of said switch 7 itionary contact means and switchblade means movable into and out of resilient engagement with said contact means, said engagement establishing frictional forces in said members normally resisting the separation thereof, a unitary pry-01f latch member pivotally mounted on said Switchblade for forcing said switchblade out of engagement with said stationary contact means, said latch member having a latch portion on one side of said pivotal axis and a pry-oft portion on the other side thereof, a catch member having the shape of a truncated cone mounted on said stationary contact means for engagement by said latch portion when said switch is closed, a stop on said latch member for limiting the movement thereof relative to said switchblade in the catch-engaging direction, resilient means for urging said latch portion in the catch engaging direction, said latch member engaging said catch in the closed position of said switch and being held thereagainst by said resilient means, the pryofi portion of said latch member engaging the flattened top of said catch member when said latch member is pivoted in the disengaging direction to force said switchblade out of engagement with said stationary contact.

6. A hook-operated dis-connect switch comprising a pair of spaced insulators, a stationary contact mounted on one insulator, a switchblade mounted on the other insulator for pivotal movement into and out of resilient engagement with said stationary contact, said engagement establishing frictional forces in said members normally resisting the separation thereof, a unitary pry-off latch member having a hook-engageable portion, means for pivotally mounting said latch member on said switchblade adjacent the free end thereof, said mounting means also providing for relative sliding movement between said latch member and said switch-blade, said latch member having a latch portion on one side of said pivotal axis and a pry-ott portion on the other side thereof, a catch member having the shape of a truncated cone mounted on said stationary contact for engagement by said latch portion when said switch is closed, a stop on said latch member for limiting the movement thereof relative to said switchblade in the catch-engaging direction, a spring engaging said latch member and said switchblade for urging said latch portion in the catch engaging direction, said latch member engaging said catch in the closed position of said switch and being held thereagainst by said spring, said pry-01f portion engaging the flattened top of said catch member when said latch member is pivoted in'the disengaging direction to force said switchblade out of engagement with said stationary contact.

References Cited by the Examiner UNITED STATES PATENTS 1,535,778 4/25 Johnson et a1. 200-169 2,566,917 9/51 Armstrong 20048 X BERNARD A, GILHEANY, Primary Examiner. ROBERT K. SOHAEFER, Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1535778 *Jul 18, 1919Apr 28, 1925Allen Johnson JosephElectrical switch
US2566917 *Mar 16, 1950Sep 4, 1951Chance Co AbHigh-voltage electric switch
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3787654 *Feb 26, 1973Jan 22, 1974Square D CoBolted contact switch with cam means for overcoming magnetic pinch forces on contact blades
US3806687 *Sep 15, 1972Apr 23, 1974Gulton Ind IncToggle and latch mechanism for switches
US4707574 *Oct 23, 1986Nov 17, 1987Kearney-National, Inc.Disconnect switch with latch
Classifications
U.S. Classification200/48.0KB, 200/325
International ClassificationH01H31/28, H01H31/00
Cooperative ClassificationH01H31/28
European ClassificationH01H31/28