US3182145A

US3182145A - Electric switch

Info

Publication number: US3182145A
Application number: US117674A
Authority: US
Inventors: Edmond B Gorman
Original assignee: McGraw Edison Co
Current assignee: McGraw Edison Co
Priority date: 1961-06-16
Filing date: 1961-06-16
Publication date: 1965-05-04
Anticipated expiration: 1982-05-04

Description

y 1965 E. B. GORMAN 3,182,145

ELECTRIC SWITCH Filed June 16, 1961 3 Sheets-Sheet 2 W" "w, ml

FIGJO FIG. ll

INVENTOR. BY [DMDND B. GORMAN ATTORNEY United States Patent 3,182,145 ELECTRHI SWITCH Edmond B. Gorrnan, Campbell, Calih, assignor, by mesne assignments, to McGraw-Edison Company, Elgin, ill, a corporation of Delaware Filed June 16, 1961, Ser. No. 117,674 17 Claims. (Cl. 290-48) This invention relates to electric switches and more particularly to disconnecting switches of the type used in high tension electrical transmission line circuits.

Disconnect switches generally comprise a relatively long, pivoted, switch blade and a companion contact. The switch blade is pivotally mounted on one insulator stack and the companion contact is mounted on another, similar insulator stack. Disconnect switches are used to sectionalize transmission lines which commonly comprise a plurality of parallel, spaced conductors carrying threephase current. The disconnect switches for a given transmission line are usually gang-operated in order to completely disconnect all the conductors of the transmission line at one time. The gang-operated switches are normally mounted so that a single operator or interconnection will, when operated, cause the switches to open simultaneously. For practical reasons, the switches are positioned adjacent to one another.

Transmission lines are subject to surges of high currents due to momentary faults and the like. Such surges cause damage to the contacts of a disconnect switch while the switch remains closed. Pursuant to the present invention, disconnect switches of novel construction are provided that are particularly well suited to withstand such conditions.

I have considered this damage as being due to the occurrence of significant mechanical deflection forces and vibrations caused by electrodynamic interaction between the switch blades. The novel switch construction is particularly well adapted to maintain firm contact pressure despite such mechanical deflection forces and vibrations. The notable success of the novel switch construction serves to demonstrate the seriousness of such deflection forces and vibrations, and it also demonstrates the eifectiveness of the novel switch construction in resisting such effects.

High voltage disconnect switches are normally equipped with arcing horns designed to function during the disconnecting operation. Arcing horns are intended to avoid arcing at the main contacts during opening of the switch. While the switch is closed, the arcing horns tend to carry part of the normal current, and during momentary surges of high current, there is a tendency of damaging arcing to occur at the arcing horn. A feature of this invention is aimed at minimizing this damage.

It is an object of this invention to reduce arcing between the switch blade and the companion contact when the switch is subjected to surge-current conditions while it remains closed. It is another object of this invention to reduce the arcing between the arcing horn and the cornpanion part of the switch blade caused by momentary surges of high current.

In known forms of disconnect switches, there has been a conflict between two design criteria, one design being directed to effect firm contact pressure and another directed to accommodate a range of mechanical misalignment between the blade and the companion contact.

It is a further object of this invention to provide a resilient mounting for the stationary contact element of a disconnect switch, to accommodate a degree of misalignment with the switch blade, and, at the same time, to provide firm contact pressure.

It is a still further object of the invention to reduce 3,182,145 Patented May 4, 1965 the stiffness of the coupling between the switch blade and the insulator stack carrying the stationary contact to thereby decrease the deflecting force on the insulator stack when the switch blade is displaced laterally by forces generated by surges of high current.

Yet another object of the invention is to provide a contact structure which allows the switch blade and the contact carrying insulator stack to vibrate at different frequencies after being subjected to a surge of high current without separation of the switch blade and the fixed contacts.

It is still another object of the invention to provide a contact element or shoe for receiving the switch blade of a high voltage disconnect switch wherein the contact pressure between the blade and the companion contact element is independent of the resilience of the mounting for the companion contact.

It is a still further object of the invention to provide a contact structure wherein the contact pressure generating means are out of the current path through the switch.

The foregoing objects are achieved in the illustrative embodiments of the invention described in detail below. The illustrative disconnect switches have a fixed contact and a relatively movable switch blade pivoted at one end and adapted to engage the contact at the other end in a closed circuit position and to be disengaged therefrom in an open circuit position. Operating means are provided for moving the switch blade between the open and closed positions. The fixed or companion contact includes a base terminal and a contact element for engaging the switch blade. Means are provided for producing firm contact pressure with the blade that is effective to suppress arcing during surge current conditions. Additionally, arc-induced damage to the arcing horn is reduced or eliminated in one of the embodiments detailed below.

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

FIG. 1 is a simplified side elevation view of an illustrative embodiment of the invention;

FIG. 2 is a plan view, on a smaller scale, of a group of disconnect switches according to FIG. 1 having gangoperating means;

FIG. 3 is an end view on a greatly enlarged scale of the contact structure of FIG. 1 with some parts broken away and other parts omitted in the interests of clarity and with the switch blade shown in phantom lines;

FIG. 4 is a sectional view of the contact structure taken along the broken line 4-4 of FIG. 3;

FIG. 5 is a side elevation view of another illustrative embodiment of the invention;

FIG. 6 is a perspective view on a greatly enlarged scale of the contact structure of the embodiment illustrated in FIG. 5 with some parts omitted in the interests of simplicity, as viewed in the general direction of the arrow 6 of FIG. 5;

FIG. 7 is a fragmentary vertical-plane sectional view taken along the line 77 of FIG. 6;

FIG. 8 is a fragmentary horizontal sectional view taken along the line 8-8 of FIG. 7;

FIG. 9 is a vertical-plane sectional view taken along the line 9-9 of FIG. 6 drawn to reduced scale; and,

FIGS. 10 and 11 are simplified diagrammatic representations of a contact structure, showing the behavior of the structure when at rest and when under stress, respectively.

Referring to FIGS. 1 and 2 the disconnect switch 20 illustrated is of the tail-twister type in which the switch blade 22 is moved into contact with a fixed contact 24, and rotated with respect thereto, by the movement of the operating means 26. The switch mounting base 28 carries the switch 24 and associated mechanism, and may be pole-mounted or secured to the superstructure of a substation, depending upon the particular application. Companion contact 24 and switch blade 22 are mounted on

fixed insulators

30, 32 respectively, secured to the base 28. The operating mechanism 26 includes a rotating insulator stack 34 driven by the interconnecting operating linkage 36. Switch blade 22 has a pivot 38 on the hinge structure 40 affixed at one end to the insulator 32. The other end of hinge structure 40 supports the rotating insulator 34 and also provides a mounting point 42 for a cable clamp, not shown.

The operating mechanism 26 is provided to swing the blade 22 about its pivot 38 to engage the fixed contact 24 and then to rotate the blade 22 about its longitudinal axis to produce contact pressure between the blade 22 and the contact 24. Operating mechanism 26 includes a pair of levers, 44, 46, secured to the switch blade 22 and rotating insulator 34, respectively. One end of lever 44 is connected by pivot 45 to the switch blade 22 and the other end is connected to rotating lever 46 by a ball joint 47.

Switch blade 22 carries raised opposed silver contacts 48 at its free end for engagement with portions of the fixed contact 24 (FIG. 3). Arcing tip 49 is atfixed to the free end of the blade 22 and extends outwardly therefrom.

Referring particularly to FIG. 2, three disconnect switches 20 are mounted parallel to one another on a cross-arm or portion of the sub-station structure, not shown. They are tied together for gang operation by interconnecting linkage 36. Lever 58 drives linkage 36 through a connection to the rotating insulator stack 34 of one of the switches.

As seen in FIG. 3, the companion or fixed contact 24 of each switch 20 includes a switch terminal and base 50 for securing the contact mechanically to the insulator stack 30. The base provides a connection point 52 for a cable clamp, not shown, and also carries the contact element 53.

Contact element or shoe 53 includes a pair of spaced

curved portions

54 and 56 to provide a central blade receiving pocket 60 (FIG. 3) having supporting

legs

61, 62 remote from the pocket. The contact element 53 may be characterized as yoke-shaped. The

internal legs

63 and 64 define walls of the pocket 60, and each leg supports a contact 66 for cooperation with the blade contacts 48. Contact pressure between the

contacts

48, 66 is provided by resilient means 68 that biases the

internal legs

63, 64 toward one another. The contact pressure producing means 68, as illustrated in FIG. 3, includes a tie bar 70 which extends through openings 72 in the

legs

63 and 64. Leaf spring groups 74, each group being united by a rivet 76, are held against

legs

63 and 64 by pins 78 (FIG. 4) that pass through the ends of tie bar 70. Rivet 76 of each spring group 74 contacts the

legs

63, 64, on the side thereof opposite the

contacts

48, 66. Each pin 78 acts as a fulcrum and effectively divides its leaf spring 74 into two lever arms, a short and relatively stiff lever arm 74a be tween rivet 76 and pin 78 and a long resilient lever arm 74b that bears against stop 80. A locating part 80a passes through each leaf-spring group 74. Spacer sleeve 82 on the tie-bar 70 between the two

legs

63, 64 limits the movement of

legs

63 and 64 toward one another when blade 22 is not present in the pocket 60. Spacer 82 also acts as a stop to limit the descent of the blade 22 with respect to the fixed contact 24, as viewed in FIG. 3, to insure alignment of

contacts

48 and 66. Little or no current flows between the spacer 82 and blade 22 since there is little contact pressure at this point.

Each of the

curved portions

54, 56, of shoe 53, together with their respective

external legs

61, 62 and

internal legs

63, 64 may be described as confronting inverted J-shaped contact elements' These elements are mounted on base 56 and have their free ends 63 and 64 joined together by a bight section 84. The entire shoe 53 as illustrated is fabricated from a continuous length of copper strip, and

' side of the blade.

4 stops 80 are held at a definite spacing by the relatively rigid section 84.

Arcing born 86 is secured to the bight portion 84 of the shoe 53 and is in contact with the arcing tip 49 as shown in FIG. 1.

The operation of the illustrative embodiment in FIGS. 1 to 4 may be described starting with the switch in the closed position. Referring to FIG. 2, when the common drive lever 58 is moved upwardly, each of the interconnected insulators 34 is caused to rotate counter-clockwise about its longitudinal axis. In each switch 20, rotation of insulator 34 causes lever 46, carried by the insulator, to rotate about the axis of the insulator. Lever 44, which is pivotally connected to the switch blade 22, is constrained to follow the rotation of lever 46 by the ball jont 47 between the levers. Rotation of lever 44 is first translated into rotation'of the switch blade 22 about its longitudinal axis to disengage the

contacts

48 and 66. Continued rotation of lever 46 then draws lever 44 to the right, raising the switch blade 22 from its resting place in the pocket 60 in the yoke-shaped contact element 53. After the contacts 48 of blade 22 separate from the contacts 60 of element 53, the arcing horn 86 and arcing tip 49 carry the whole current. Arcing usually occurs as arcing tip 49 swings out of contact with the upper end of arcing horn 86. In the fully open position, the switch blade 22 is at an angle of approximately 90 to the mounting base 28.

The switches 20 are closed by reversing the movement of the drive lever 58. The initial portion of the rotation of lever 46 returns blade 22 from the vertical open position to the horizontal position shown in FIG. 1. Continued movement of the

levers

44 and 46 causes the switch blade 22 to rotate about its longitudinal axis. The width of the pocket 60 is controlled by the spacer 82 and the separation between the

legs

63, 64 is normally less than the greatest width of the contact arm 22 measured across the contacts 48. The blade 22 first enters the pocket freely, with contacts 48 cocked at an angle. Then rotation of the blade causes the contacts 48 to wipe across the contacts 66 in the

legs

63, 64, forcing them apart against the bias of the leaf springs 74. The amount of contact pressure generated is substantially dependent upon the leaf springs and is largely independent of the resilience of the

legs

63, 64. The aforedescribed opening and closing operations are common to all the switches in a gang by virtue of the interconnecting linkage 36.

In typical prior art devices, the inherent resilience of the separate confronting contact carrying members produces the contact pressure with the blade. Under surges of high current I have found that the switch blade is attracted or repelled by adjacent switch blades in the gang, involving strong electromagnetic deflection forces and vibration. When the blade is subjected to the lateral shift due to electromagnetic attraction, the blade is driven out of contact with the companion contact element at one Those contact elements or elements at the other side of the blade, which do remain in contact with the switch blade, are severely overloaded since only one half the contact area is available and the switch is subjected to severe levels of surge current. Arcing occurs between the blade and the contact members, which results in contact damage and increased contact resistance. There is also a possibility that the contacts and the blade may weld together.

The effectiveness of the contact structure in maintaining contact pressure despite lateral deflection of the switch blade is demonstrated by FIGS. 10 and 11. The yokeshaped contact shoe 53 grips the blade 22 in the blade receiving pocket 60. This pocket, which includes contacts 66, legs 63, bight section 84 and the contact-biasing means including leaf-spring groups 74, is resiliently supported on

conductive legs

61 and 62. This resilient support promotes entry of the switch blade into the pocket despite minor misalignment. However, the pocket is capable of bodily shift toward either contact 66 without loss of Q contact pressure at the other contact 66. Under severe electromagnetic stress, the pocket 60 is able to move laterally with the blade 22 without either contact 66 becoming parted from its switch-blade contact 48 because the pocket is clamped to the blade. If the blade moves toward leg 61, pushing leg 63 before it, the tie bar 70, spring 74 and bight section 84 assure that the other leg 64 follows and maintains firm contact pressure. The natural resilience of the

external legs

61, 62 of shoe 53 accommodates the movement at the end of the switch blade 1 and restores the blade 22 to its initial location after the surge passes. The movements can occur without subjecting the insulator stack 30, which carries the fixed contact 24, to high deflecting stresses. Additionally the blade 22 and insulator stack 30 may vibrate at ditferent frequencies after the surge passes without separation of the contacts. The contact assembly thus forestalls any tendency of arcing and avoids arc damage to the contacts while, at the same time, retaining the desired resilience at the companion contact that receives the switch blade.

Another feature of the invention resides in the connection of the arcing horn 86 to the bight portion of the shoe 53. The path of current flowing between the arcing tip 49 and normal current-carrying portion of the contact shoe 53 is of higher impedance than the path of current directly from the blade 22 to shoe 53 through the

contacts

48, 66 since the current path through the arcing horn includes the portion of the arcing horn 86 between the tip 49 and the bight portion 84 and the

legs

63, 64 to the vicinity of the

contacts

48, 66. Therefore the current distribution is such that normally, and even if the tip 49 and horn 86 should lose contact pressure and separate slightly during a high current surge, there is little danger of arcing damage occurring at the arcing contacts. On the other hand, it has been found that when the switch 20 is opened normally, when it is required to interrupt only line-charging current, the relatively slight impedance represented by

portions

84 and 86 and

portions

63, 64 in parallel does not interfere with the normal function of the arcing horn 86 and tip 49.

Prior art arcing horns are purposefully of a design to have a minimum of impedance (often lower than the associated main contacts) with the intention that the arc that occurs as the switch is being opened shall be drawn only between the horn and tip. However, the low impedance of the arcing-horn contact in disconnect switches of usual construction causes damaging arcing to occur at the arcing contact under high current surges when the switch remains closed. This part of the arcing horn should remain in good condition so that it will provide a reliable contact to carry current when the switch blade twists and the main contacts separate. Arc-damage to this part of the arcing horn tends to produce damaging arcing at the main contacts during twist-parting of the main con tacts.

There is a common type of disconnect switch that uses separate confronting inverted-J conductors for the main stationary contacts, which are carried on the insulatorstack terminal, and in the closed condition of the switch the arcing contacts provide a current path directly between the switch blade and the arcing horn. The latter path is of lower impedance than the current path through the J-shaped conductors of the main contacts. Consefir quently there is a tendency of accentuated arcing occurring that the main contact of the switch blade twists and parts from the stationary contact remains in good condition and therefore effective to do its job. That there is greater impedance in the path through the arcing contact than through the main-contact path is of little concern in respect to transfer of the entire switch current through the arcing contact when the switch is being opened and is to interrupt line-charging current. It should be remembered that this current is of a far lower order of magnitude than the load and the surge currents that occur while the switch remains closed and when the relative inductances of the two paths through the novel switch are of special significance.

Another embodiment of the invention is illustrated in FIGS. -9. Parts corresponding to those described in connection with the embodiment of FIGS. 14 are designated by corresponding primed numbers. The disconnect switch is intended for use with higher voltage and current. In order to handle the higher currents, a plurality of yoke shaped contact elements 53 are provided in the stationary contact 24'. Each of the contact elements 53' is secured to the switch terminal and contact base by conventional means.

Referring to FIGS. 6 and 9 contact pressure in the blade receiving pocket is supplied by spring bias means 68'. In this embodiment, spring bias means 68' includes a coil spring 88 positioned about a rod 90 which passes through openings 92 in the legs 63', 4', of the element 53'. Spring 88 reacts against a pair of collars 94 slidable on the shaft 96. The collars 94 pass through the openings 92 in the

legs

63, 64 and each engages a lever 96 which has a fulcrum in the form of a pin 78' through the tie bar 7%). The opposite ends of levers 96 bear against the respective legs 63' and 64 opposite the contact areas 66 thereon. Each lever 96 is retained on the tie bar 70 by pin 78. Pins 98 which pass through the ends of the shaft limit pivotal movement of the levers 96 when spring 88 urges the collars 94 against the levers 96. Contact pressure in pocket 66 is produced by the actions of the springs 88 in this manner. Spacer 82' about the tie rod 70 and the pins 98 through shaft 99 limit the inward movement of the legs 63, 64' toward one another, and provide assurance that pocket 60' will admit the switch blade when the switch is to be closed, and further assurance that contact pressure is removed when the switch blade is twisted to carry contacts 48' away from contacts 66.

Referring to FIGS. 6, 7 and 8 a U-shaped arcing horn 100 having free ends 161 is secured by its bight portion 102 to the base portion 104 of blade stop 1%. Blade stop 106 includes a pair of erect, rigid, widely spaced arms 1%, 11h spanned by .a relatively resilient metal member 112 as of steel. The blade stop 105 is positioned intermediate the arcing horn 98 and the first of the aligned series of contact'elements 53 and receives the switch blade 22. This limits the movement of the switch blade into the receiving pocket 60 so as to assure alignment of contacts 48' and 66'. The blade stop 106 is insulated from the base 56' by insulation 114 which also surrounds and insulates the connecting bolts 116. The blade stop 106 and arcing horn 100 are connected to the bight 84 of the first adjacent contact element 53' by a flexible jumper 118.

The operation of the embodiment in FIGS. 5-9 is similar to that described in conjunction with the description of FIGS. l-4. The operating mechanism 26' drives the switch blades of disconnect switches 20 into and out of engagement with the stationary contact 24. Three switches 20 are mounted for gang operation in an arrangement similar to FIG. 2.

The operating mechanism 26 (FIG. 5) drives the switch blade 2-2 into the blade receiving pocket 60 where in the blade 22 encounters the horizontal portion 1-12 of the blade stop 106 thus limiting the movement of the switch blade into the pocket 60. The resilience of member 112 absorbs the closing shock. Each of the plural a yoke-shaped contact elements 53' functions as its singular counterpart 53 in the embodiment shown in FIGS. 1-4. In the current embodiment rigid levers 96 transmit the contact pressure generated by coil springs 38 to the area of contact engagement.

Under severe stress as caused by high current surges the blade receiving pockets 60' are all free to deflect in response to electrodynamic forces, to move with and adjust to the newly assumed lateral position of switch blade 22. Arcing horn 100 is connected to the bight 84' of the first contact element 53' and therefore provides a current path whose impedance is at least equal to, and actually greater than, the impedance of the current path from the contact area 66' to the base 50. Therefore, as in the earlier described embodiment, arcing will be suppressed between the switch blade 22 and the arcing horn 100 under momentary surges of high current.

Various additional modifications of the above embodiments of the invention will readily occur to those skilled in the art, and therefore the invention should be broadly construed in accordance with its full spirit and scope.

What I claim is:

1. A multi-pole switch comprising a plurality of aligned and coordinated single pole switches, each of said single pole switches having a stationary contact and a switch blade moveable into an out of circuit making engagement with said contact, said switch blades being swingable in respective parallel planes and operable in twist motions about their respective axes, means rnechanically coordinating the movements of said switch blades, said contact of each pole including a base terminal, a yoke-shaped contact element having a central switch blade receiving pocket, said pocket being fixed with its opening facing its switch blade during the swinging movement thereof, said yoke-shaped contact element including resilient means having a portion secured to said base terminal, said portion being located at a point on said element remote from said pocket and constituting the sole means of engagement between said element and said base terminal, means for maintaining minimum separation between the legs of said pocket means independent of said resilient means for resiliently urging said legs toward one another for producing contact pressure with said blade, said pocket being capable of lateral movement in response to the lateral movement of said switch blades due to high currents without loss of contact pressure in said pocket due to said lateral movement.

2. A multi-pole switch comprising a plurality of aligned and coordinated single pole switches, each of said single pole switches having a stationary contact and a switch blade movable into and out of circuit making engagement with said contact, said switch blades being swingable in respective parallel planes, and being operable in twist motions about their respective axes, means coordinating the swinging and twisting movements of said switch blades, said stationary contact of each pole including a base terminal, a pair of inverted opposed J- shaped contact elements, each of said contact elements having the long legs thereof secured at one end to said base, the other ends of said long legs being free for lateral deflection, means mechanically connecting the ends of the short legs of each of said opposed contact elements and thereby defining a blade receiving pocket, said pocket being fixedly disposed with the opening of the pocket being connected to the other ends of said long legs and facing said switch blade during the swinging movement thereof, and means independent of said long legs resiliently urging said short legs toward one another, the contact pressure produced between said contact elements and said switch blades being independent of the lateral deflection of said switch blades perpendicular to said planes under high current conditions.

3. A multi-pole blade type disconnect switch comprising a plurality of blade-type switches having a common mechanical interconnection for simultaneously opening and closing said switches, each of said switches having a fixed contact, a pivoted switch blade adapted to engage said contact in a closed circuit position and to be disengaged therefrom in an open circuit position, said fixed contact including a base portion and a generally Ushaped blade receiving pocket element, means urging the legs of said pocket toward each other to provide contact pressure between blades and said pocket in the closed position thereof, said urging means being disposed exteriorly of said pocket, and a pair of elongate resilient support means each having one end engaging one of the legs of said pocket element and another end afi'ixed to said base for resiliently mounting said pocket elements to provide for individual lateral shift of each of said switch blades during the flow of high current surges through said multi-pole switch, said another ends of said resilient support means being the sole means of engagement between said resilient support means and said base.

-4. A high voltage disconnect switch comprising a contact, a pivoted switch blade adapted to engage said contact in a closed circuit position and to be disengaged therefrom in an open circuit position, and moving means for moving said switch blade between said opened and closed circuit positions, said contact including a base terminal a plurality of yoke-shaped contact elements having aligned central U-shaped portions each forming a switch blade receiving pocket, said yoke-shaped contact elements having resilient outer legs secured to said base terminal, a tie bar extending through each said pocket from one leg of the pocket to the other, a spacer on said tie bar to control the minimum separation of the legs of said pocket, pivot points formed on said tie bar external to said blade receiving pocket, a leaf spring fulcrumed on each of said pivots for providing contact pressure between said legs of said U-shaped portion and said blade when received there'between, each said leaf spring having one lever arm bearing against the adjacent leg of the pocket, a stop between the other lever arms of said leaf springs, and an arcing horn, means securing said arcing horn to said base terminal but electrically insulating said born from said base terminal, a conductive jumper between said arcing horn and the bight portion of the first adjacent blade receiving pocket, the impedance of the conductive path from said arcing horn to said base being at least equal to the impedance of the conductive path from each of said pockets to said base and the contact pressure in said blade receiving pocket being determined predominantly by said leaf springs, and said pocket being movable laterally with said blade in response to short circuit currents without loss of contact pressure.

5. A switch comprising a contact, a pivoted switch blade adapted to engage said contact in a closed circuit position and to be disengaged therefrom in an open circuit position, and moving means for moving said switch blade between said opened and closed circuit positions, said contact including a base portion and a yoke-shaped contact element having a central U-shaped portion having legs forming a switch blade receiving pocket, a tie bar extending across said pocket from one leg to the other, a spacer between said legs to maintain a minimum separation of the legs of said pocket, pivot points formed on said tie bar external to said blade receiving pocket, a leaf spring fulcrumed on each of said pivots for providing contact pressure between said legs of said U-shaped portion and said blade when received therebetween, each said leaf spring having one lever arm in contact with the adjacent leg of the pocket and another lever arm spaced from said leg by a stop between said other arm of said leaf spring and said leg, said stop biasing said one lever arm of said leaf spring against said leg of the pocket, the contact pressure in said blade receiving pocket being determined predominantly by said leaf springs and said pocket being movable laterally with said blade in response to short circuit currents, said contact element including elongate resilient support members each having one end engaging one of said legs and another end secured to said base portion, said another ends constituting the sole means of engagement between said contact element and said base portion so that said contact element is free for limited lateral deflection.

6. A high-voltage disconnect switch comprising a fixed contact, a switch blade movable between open and closed circuit positions and being engageable with said fixed contact in the closed position, said contact blade being of a given width in one direction transverse its longitudinal axis, and having a contact portion of greater Width than said given width engageable with said fixed contact, said fixed contact including a resilient contact in the form of a switch blade receiving pocket, means urging the walls of said pocket toward each other and restraining said walls to a minimum separation greater than said given width and less than said greater width to provide contact pressure between said pocket and said switch blade substantially independent of the resilience of said element, means for moving said switch blade with its greater width parallel to the direction of blade movement into engagement with said blade receiving pocket and means for rotating said switch blade about its longitudinal axis to bring said contact portion of said switch blade into contact with said blade receiving pocket, said fixed contact also including a base portion, and means for resiliently mounting said resilient contact on said base portion at a point remote from the blade receiving opening in said pocket, said last mentioned means being the sole means of engagement between said base portion and said resilient contact so that said pocket is free for limited lateral displacement.

7. A high voltage disconnect switch comprising a contact, a pivoted switch blade adapted to engage and disengage said contact, and moving means for moving said switch blade between opened and closed circuit positions, said contact including a base terminal, a yoke-shaped contact element having a central switch blade receiving pocket including spaced legs for receiving said switch blade, and means supporting said yoke-shaped contact element resiliently to said base terminal at a point on said element remote from said pocket, said last mentioned means being the sole means of engagement between said base terminal and said contact element so that the end of said contact element remote from said base terminal is free for limited lateral deflection.

8. A high voltage disconnect switch comprising a contact, a pivoted switch blade adapted to engage and disengage said contact, and moving means for moving said switch blade between opened and closed circuit positions, said contact including a base terminal, a yoke-shaped contact element having a central switch blade receiving pocket including spaced legs for receiving said switch blade, and means supporting said yoke-shaped contact element resiliently to said base terminal at a point on said element remote from said pocket, said last-mentioned means being the sole means of engagement between said base terminal and said contact element so that the end of said contact element remote from said base terminal is free for limited lateral deflection, means for maintaining separation of said legs, means independent of said supporting means for resiliently urging said legs toward one another for producing contact pressure with said blade despite lateral deflection of said switch blade in response to high currents.

9. A fixed contact member for a blade-type disconnect switch including a base, a plurality of resilient contact members having aligned blade receiving pockets, each of said contact elements being provided with means constraining the legs of each of said pockets against separation to provide individual contact pressures between said pockets and said blade, and individual means resiliently mounting each of said contact elements on said base at a point remote from the openings in said pocket and being the sole means of engagement between said contact elements and said base so that said contact elements are free for limited lateral deflection and displacement.

10. A fixed contact member for a blade-type disconnect switch including a base, a plurality of resilient contact elements having aligned blade receiving pockets, an arcing horn, means for insulating said arcing horn from said base, and means for connecting said arcing horn I electrically to the bight portion of the pocket of said first adjacent contact element, the impedance of the current path through said arcing horn to said base thereby being greater than the impedance of the current path from said blade receiving pocket to said base.

11. A fixed contact member for a blade-type disconnect switch including a base, a resilient contact element formed to provide a blade receiving pocket, a tie bar spanning the legs of said pocket, contact means on the confronting surfaces of the legs of said pocket for engaging said blade, biasing means pivoted on said tie bar and engaging the outer surfaces of said legs opposite said contact means for urging the said contact means into engagement with said blade and to thereby produce contact pressure between said blade and said element, and a paid of elongate resilient members each having one end engaging one of said legs and another end engaging said base for resiliently mounting said contact element on said base, said another ends constituting the sole means of engagement between said resilient contact element and said base so that said resilient contact element is free for limited lateral deflection, said urging means being independent of said elongate means.

12. A fixed contact member for a blade-type disconnect switch including a base, a resilient contact element in the form of a blade receiving pocket, additional means to provide contact pressure including biasing means urging the walls of said pocket toward each other, means resiliently mounting said contact element on said base, an arcing horn secured to but insulated from said base, and a flexible jumper electrically connecting said arcing horn to said blade receiving pocket, the impedance of the current path through said arcing horn to said base being substantially equal to or greater than the impedance of the current path from said blade receiving pocket to said base.

13. A fixed contact member for a blade-type disconnect switch including a base, a resilient contact element in the form of a blade receiving pocket having walls resiliently bearing against the blade of the switch in its closed position, additional means urging the walls of said pocket toward each other to provide contact pressure, means resiliently mounting said contact element on said base, an arcing horn secured to but insulated from said base, and means electrically connecting said arcing horn to said blade receiving pocket whereby the impedance of the current path through said arcing horn to said base is at least equal to the impedance of the current path from said blade receiving pocket to said base.

14. A fixed contact member for a blade-type disconnect switch including a base, a resilient contact element in the form of a pocket having a blade receiving portion, means urging the walls of said pocket toward each other in addition to any bias due to the resilience of said walls to provide contact pressure between said pocket and said blade, conductive means engaging said element adjacent the blade receiving portion of said pocket for resiliently mounting said contact element on said base, an arcing horn electrically isolated from said base and electrically connected to said pocket at a point remote from said conductive means so that the impedance between said arcing horn and said base is greater than the impedance of the current path from said blade receiving portion to said base.

15. A fixed contact member for a blade-type disconnect switch including a base, a resilient contact element having a blade receiving pocket, an arcing horn, means for insulating said arcing horn from said base, and means for connecting said arcing horn electrically to the bight i 1 portion of the pocket of said contact element, the impedance of the current path through said arcing horn to said base thereby being greater than the impedance of the current path from said blade receiving pocket to said base.

16. A fixed contact structure for the switch blade of a high voltage disconnect switch, including a base terminal, a pair of inverted J resilient contact elements, the long legs of the J elements terminating at said base terminal and the short legs of the J elements providing confronting blade-engaging main contacts, and an arcing horn insulated from said base terminal and having an electrical connection to the short legs of said J elements which is more remote from said long legs than the blade-engaging portion of said J elements so that the impedance between said base and said arcing horn is greater than the impedance between said base and the blade-engaging portion of said J elements.

17. A fixed contact member for a blade-type disconnect switch including a base, a resilient contact element including a blade-receiving pocket having spaced legs and resilient support means engaging said base at a point remote from said pocket and constituting the sole means of engagement between said element and said base, means independent of said resilient means for urging the legs of said pocket toward each other to provide contact pressure between said pocket and said blade without dependence upon the resilience of said element, and means resiliently mounting said contact element on said base.

References Cited by the Examiner UNITED STATES PATENTS 2,894,101 7/59 Lindell et a1. 20048 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

Claims

15. A FIXED CONTACT MEMBER FOR A BLADE-TYPE DISCONNECT SWITCH INCLUDING A BASE, A RESILIENT CONTACT ELEMENT HAVING A BLADE RECEIVING POCKET, AN ARCING HORN, MEANS FOR INSULATING SAID ARCING HORN FROM SAID BASE, AND MEANS FOR CONNECTING SAID ARCING HORN ELECTRICALLY TO THE BIGHT PORTION OF THE POCKET OF SAID CONTACT ELEMENT, THE IMPEDANCE OF THE CURRENT PATH THROUGH SAID ARCING HORN TO SAID BASE THEREBY BEING GREATER THAN THE IMPEDANCE OF THE CURRENT PATH FROM SAID BLADE RECEIVING POCKET TO SAID BASE.