US2420485A - Electrical switch with kinetic energy dissipating means - Google Patents

Description

S. H. KAST May 13, 1947.

ELECTRICAL SWITCH WITH KINETIC ENERGY DISSIPATING MEANS 2 Sheets- Sheet 1 Filed Aug. 5, 1942 GKOUND/NG 3 WITCH 1 0 5 CONNECT SW/ TCH May 13, 1947. s. H. KAST 2,420,485

ELECTRICAL SWITCH WITH KINETIC ENERGY DISSIPATING MEANS Filed Aug. 5, 1942 2 Sheets-Sheet 2 ii j: a

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Patented May 13, 1947 UNITED" STATES PATENT OFFI ELECTRICAL SWITCHW'ITH'KINETIC ENERGY DISSIPATING MEANS Samuel H-. Kast; Greensburg. Pa., assignor to Railway and Industrial Engineeringpompany, Greensburg, 1a., a corporation of Delaware Application August 5, 1942-; Serial No-4'53;711

Claims. 1

This invention relates to electrical switches and to constructions that are appropriate for use-in disconnect switches but that are particularly'use ful in grounding switchesthat are closedautomatically by heavy springs ina time interval of the order of 8 to 10 cycles on a 60 cycles per second distribution circuit.

The switch blade must be of relatively light weight topermit rapid acceleration whenthe operating. mechanism is tripped; and the kinetic energy of the rapidly-moving rblade can best be absorbed bycontact elements that engage *under appreciable pressure tobringthe blade to --a slid ing stopi Th'eopening movement of the blade must overcome-the friction of the blade onthe jawi element but it is possible to reduce-this frictional resistance of'the contact membersduring the opening of the blade.

An object of this invention is to provide an electrical switch in which the blade contact hasa relatively long travel within aresilient jaw contact whose opposed contact elements establish a substantial pressure upon the blade contact; thereby dissipatingthe-kinetic energy of the moving blade and establishing a contact engagement of low resistance, the blade contact being of suchdesign that itcollapses upon an opening movement of the "switch blade to reduce or eliminate the pressure exerted on-the movable contact by the jaw contact. An objectisto provide a switch including a blade contact of two sections pivotally connected to form a toggle that is spread during a closing-movement of the switch blade to establish a high pressure engagement with the opposed contact elements of a jaw contact, and is collapsed upon an opening movement of the blade to relieve the contact pressure and the frictional resistance to movement of the switch blade. Another object is to provide aswitch jaw contactincluding opposed contact elements of relatively great length, as measured along the path of move ment'of the bladecontact,- that are pivotally connected and'spring pressed-towards each other toexert upon amovable blade contact a pressure that is substantially: independent of the position of the blade contact within the jaw contact. More specifically, anobject is to provide a jaw contact of the type stated in which the elongated contact elementsof the jaw contact are pivotall-y connected forangular movement about an axis or axes substantially parallel to the pathof movement of the blade'contact asit moves into the jaw contact.

These' an'd' otheriobjects" and advantages of the invention' will be-apparent from the following 2.. specification when-taken with the accompanying; drawings in'which:

Fig; 1 is-a fragmentary front elevation of a grounding :switch embodying the invention;

Fig. 2 is a fragmentary top planview of the switch; with the switch blade shown in position approaching, but outside of, the jaw contact;

Fig. 3 -is aside elevation of the jaw contact;

Fig; 4 is a fragmentaryperspective view of the contact end of the blade; and

Figs- 5 and-6 are end views of the-contact blade showing; the contact members in spread and in collapsed positions, respectively.

In the drawings, the reference numeral identifies a-stationary insulating column that supports the-base 2 of the hinge terminal of a disconnect switch 3 that is to be grounded by the switch that embodies the present invention. I-he jawcontact of thegrounding switch is mounted upon the terminal base '2, and the blade 4 of the grounding switch is supported upon an operating. shaft 5 that is journalledupon thesteel framework 6 on which the insulator column I is mounted.

The operating shaft 5' is preferably actuated by a strong spring, not shown, that accelerates the blade 4 rapidly to effects, quick closure of the groundingrswitch, Whether operated by a strong springor manually; the blade 4 is moving rapidly asit reaches the contact jaw, and its kinetic energymust-be dissipatedat a relatively slow rate to-avoid excessive stresses in the-blade 4.- The kinetic energy is dissipated by a relatively long travel of the switch blade within the jaw against africtional resistance that is substantially constant over the entire range of movement of the blade within the jaw.

The switch'jawcomprises a yoke or U-shaped base i thatis-bolted to the disconnect switch base 2, and'apair of opposed contact elements- 8, 8' that-are pivotallysupported upon the base I on shafts 9 that are substantially parallel to a tan ent :to the arcuate-path of-movement of the contact end of the blade as it enters the switchjaw: The elongated contact surfaces 8' of the contact elements 8 are-substantially parallel to eachotherand to the shafts 9, and-areurged toward each other by a pair of springs l0= that are supported on and between flanges ll of the contact elements. The springs are seatedin recesses inone of the flanges l l and are-mounted on shouldered studsi 2-that-are threaded into theother flange ll 'foradjustment to determine the pressure exerted upon the switch blade by'the jaw-contact elements. A bolt I3- extends through the flanges H and carries a nut [4 that may be turned down upon the bolt to determine the minimum width of the contact jaw when the grounding switch is open. Flexible current-carrying jumpers [5 are connected between lugs IS on the contact elements 8 and the jaw base I, the jumpers being preferably fitted over the shafts 9 and clamped to the base 1 by nuts I! that are threaded upon shafts 9. A rubber stop I8 is supported below the contact surfaces 8 by an inverted T-shaped member [9 that is secured to the base I but, in normal operation, the blade 4 will be arrested by frictional resistance before it reaches the stop [8.

The contact means of the switch blade 4 has a normal width somewhat in excess of the spacing of the jaw contact surfaces 8' when the switch is open, and the springs It! therefore establish a high pressure contact engagement that provides the frictional resistance for arresting the rapidly moving switch blade and affords a high pressure contact engagement of low electrical resistance. The blade contact means comprises a pair of laterally alined contact members 20 that are pivotally mounted on the reduced diameter end 2| of the blade 4 for rocking movement about the axes of the blade. Torsion springs 22 are connected between the contact members 20 and flanges 23 on the blade 4 to urge the contact members in opposite directions to engage the arcuate stop 24 that positions the contact members in diametrical alinement corresponding to a maximum width of the blade contact means.

The frictional resistance to movement of the blade into the resilient contact jaw establishes forces on the contact members 20 that act in the same sense as the springs 22 to hold the contact members in spread or maximum width position. The frictional resistance operates in opposition to the springs 22 upon an opening movement of the switch, and the springs 22 yield to permit a rocking movement of the contact members to reduce the pressure exerted upon the blade contact members by the contact jaw elements, thereby reducing the frictional resistance to an opening movement of the switch.

The switch blade assembly is of relatively light weight and can be closed quickly by a spring mechanism, not shown, and the high speed movement is gradually slowed down by friction between the jaw contact elements 8 and the blade contact members 20. This frictional resistance may be substantially constant over the full range of movement of the blade within the jaw, but it can be increased or decreased with the movement of the blade contacts by appropriate design of the contact surfaces 8' of the jaw contact elements. The frictional resistance is substantially reduced upon an opening movement of the switch by the rocking of the blade contact members in opposition to the forces exerted by the springs 22.

A preferred embodiment of the invention has been illustrated and described but it is to be understood that the invention is not limited to automatic grounding switches and that various changes may be made within the spirit of my invention as set forth in the following claims.

I claim:

1. In an electrical switch, a blade pivotally supported for angular movement in opposite directions for switch closing and switch opening movements respectively, contact means at the outer end of the blade, a jaw contact for engagement by said blade contact means and including opposed relatively movable contact elements having elongated contact surfaces substantially parallel to each other and to a line parallel to the arcuate path of the blade contact means as it enters the jaw contact, elongated pivot means supporting at least one of said contact elements for rocking movement about an axis parallel to said contact surfaces, spring means urging said contact elements towards each other to exert a substantial pressure upon the blade contact means as it moves into and along the jaw contact, and means limiting the relative rocking movement of said contact elements to determine the minimum spacing of said contact surfaces upon movement of blade contact means out of the jaw contact.

2. In an electrical switch, the invention as claimed in claim 1, wherein said jaw contact includes a base member and said elongated pivot means supports each of said contact elements on said base member for rocking movement about spaced axes each parallel to said contact surfaces.

3. In an electrical switch, the invention as claimed in claim 1, wherein said jaw contact includes a base member and said elongated pivot means supports each of said contact elements on said base member for rocking movement about spaced axes each parallel to said contact surfaces, and said spring means is supported on and between said contact elements to exert pressure thereon to urge the blade-engagin contact surfaces of said contact elements towards each other.

4. In an electrical switch, the invention as recited in claim 1, wherein said blade contact means include contact members supported on said blade for relative movement, under the frictional drag exerted on said contact members by the springpressed contact elements during a switch opening movement of said blade, to decrease the eifective width of the blade contact means, thereby automatically to reduce the frictional resistance to movement of the blade contact means out of said jaw contact to a value substantially lower than that of the frictional resistance to movement of the blade contact means into and along the jaw contact.

5. In an electrical switch, a jaw contact including opposed and relatively elongated contact elements resiliently pressed towards each other, a switch blade and means supporting the same for angular movement in opposite directions to carr the contact end thereof into and out of said jaw contact, and contact means on said blade for engagement with said contact jaws; said contact means including a contact member pivoted upon said blade for angular movement about the axis thereof and movable to vary the effective width of the contact means, and spring means urging said contact member into position to present a maximum width of said contact means for wedging engagement with said contact jaw.

6. In an electrical switch, the invention as recited in claim 5, wherein said spring means exerts a force on said contact member lessthan that arising from the frictional resistance to movement of the contact means out of said contact jaw upon an opening movement of the switch blade, whereby said contact is automatically rocked to reduce the frictional resistance to movement upon switch opening movement of the switch blade.

'7. In an electrical switch, the invention as recited in claim 5, wherein said contact means comprises two contact members alined transversely of the switch blade and pivoted thereon for rocking movement about the axis of the blade, and said spring means exerts forces upon said contact members in the same sense as that of the forces developed upon said contact members by the frictional resistance to movement of said contact members into said contact jaw.

8. A switch jaw for cooperation with a pivotally mounted switch blade and comprising a base, a pair of contact elements, each contact element having an elongated contact surface substantially parallel to a tangent to the arcuate path of movement of a switch blade as it enters the switch jaw, elongated shafts pivotally mounting said contact elements upon said base for rocking movement about axes substantially parallel to the associated contact surface, and spring means urging said contact surfaces towards each other.

9. A switch jaw as recited in claim 8, wherein said contact elements each includes a flange extending to the side of their respective supporting shafts opposite their elongated contact surfaces, and said spring means comprises compression springs supported between said flanges of the contact elements.

10. A switch jaw as recited in claim 8, wherein said contact elements each includes a flange extending to the side of their respective supporting shafts opposite their elongated contact surfaces, and said spring means comprises compression springs supported between said flanges of the contact elements, in combination with a bolt extending through said flanges to limit the minimum spacing of said elongated contact surfaces SAMUEL H. KAST.

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

UNITED STATES PATENTS Number Name Date 2,095,554 Maseng Oct. 12, 1937 888,760 Smythe May 26, 1908 1,935,597 Koppitz Nov. 14, 1933 792,860 Sundh June 20, 1905 856,737 Sill June 11, 1907 2,254,914 Rugg Sept. 2, 1941 638,036 White Nov. 28, 1899 615,665 Guett Dec. 6, 1898 2,309,909 Koppitz Feb. 2, 1943 2,306,117 Dunlap Dec. 22, 1942 964,037 Lux July 12, 1910 981,452 McNally Jan. 10, 1911 FOREIGN PATENTS Number Country Date 603,820 Germany Oct. 9, 1934 378,567 Great Britain 1932

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