US2789189A - Disconnect switch - Google Patents

Description

April-16, 1957 Filed Oct. 20, 1952 4 Sheets-Sheet 1 INVENTOR$ Haw/14w d-e/wi/z Jen/0e #1517 BY April 16, 1957 H. w. GRAYBlLL ET AL 9 DISCONNECT swz'rcn Filed Oct. 20, 1952 4 Sheets-Sheet 2 April 16, 1957 Filed Oct. 20, 1952 GRAYBILL ET AL DISCONNECT SWITCH 4 Shets-Sheet a IN V EN TOR5 #04024; M- fiewyiru.

lmwe Allin? April 16, 1957 H. w. GRAYBILL ETAL DISCONNECT SWITCH 4 Sheets-Sheet 4 Filed Oct. 20, 1952 Irma/rm United States ?atent (l 2,789,189 DISCONNEQT SWITCH Howard W. Graybill and Arthur M. Zeth, Greenshnrg, Pa., assignors, by mesne assignments, to I-T-E Circuit Breaker Company, Philadelphia, Pa, a corporation of Pennsylvania Application Gctoher 20, 1952, Seria 315,629 8 Claims. (Cl. 200176) Our invention relates to disconnect switches and is more particularly related to a novel switch for a uniform and consistent high pressure spot contact which has advantages over the prior art switch when subjected to a short circuit condition.

Our invention relates to disconnecting switches of the high voltage hook-stick operated type. These switches have one or more contact blades, usually rectangular in cross section, which have one end attached to a hinge terminal and which rotate about the hinge terminal into and out of engagement with a second terminal or break jaw to close and open the switch. This operation is usually accomplished from a remote point by means of an insulated switch stick which engages a pull ring at the break end of the blade.

The prior art disconnect switches have a Single or plurality of high pressure spot or line contacts in preference to surface to surface contact. That is spot or line contact of high pressure and limited area, permits metal to metal contact through dust, oxide, and sulphide films and ice.

However, heretofore, in order to obtain high pressure spot contacts the switch blades to be used in the disconnect switches were subjected to a coining operation at the break jaw end of the contact blades. That is the blade was coined on diametrically opposite sides in order to obtain protrusions which would act as contact buttons for the switch blade. extra metal which would form a portion of the contact button, it was necessary to reduce the cross sectional area of the blade immediately adjacent to the contact button. This type of switch blade had several disadvantages. For example, during short circuit conditions the heat generating thereby at the contact spots had to pass through the constricted area which resulted from the coining operation. The constrictions not only increased the heat generated but also limited the heat flow and thereby resulted in increased temperature rise of the coined con-, tact spot.

Furthermore, the fact that the coined contacts were in diametrically opposite sides of the blade arm resulted in extreme concentration of the heat generated thereby causing possible damage to the blades.

Accordingly, the net result is a marked limitation of the short circuit current the disconnect switch will carry without damage thereto.

It is also noted that the disconnect switches of the prior art use annealed copper stationary contact fingers which are backed up by phosphorous bronze springs in order to achieve resilient means to obtain high contact pressure. However, this system results in a switch having indeterminate contact pressure which could not be calculated due to the fact that stresses in the copper fingers are unknown. Furthermore, the copper fingers are subjected to cold flow so that the contact pressure does not remain constant and even when the switch is first assembled it is possible to have a wide variation in the contact pressure depending on how the pressure is adjusted.

However, in order to obtain the.

In the novel disconnect switch of our invention, we

propose to obtain high pressure spot contact by providing the blade member with two or more raised contacts of spherical radius on one side to touch the break tongue and one or more raised contacts of spherical radius on the other side to touch the contact spring member wherein ice the raised contacts are spaced apart along the axis of the blade. The raised contacts are created by a forming operation rather than a coining operation and hence are created without the necessity of reducing the cross sectional area of the blade.

Thus with this novel construction for the switch blade the short circuit capacity of the disconnect switch will be materially increased due to the fact:

1. That the contact spots on either side of the blade are spaced from each other:

2. That the contact surfaces are raised contacts of spherical radius with no constrictions on reduced cross sectional area.

Hence with the above mentioned changes, the heat generated will be:

1. materially reduced due to the increased cross sectional area available and 2. more readily dissipated due to the fact that the raised contacts are spaced from each other.

Our novel disconnect switch also difiers from the switch of the prior art by providing stationary spring contact members of a precipitation hardened alloy which are cantilevered from the base of the switch to replace the annealed copper fingers backed up by phosphorous bronze springs used in the prior art arrangement. Our invention also includes precision spacers positioned between the break tongue and the above mentioned spring contact members to insure a controlled distance between these two units, to enable the blade members to impart a predetermined cantilever stress on the spring contact members to supply proper contact pressure.

A novel latching device, to maintain the switch in closed position during the occurrence of a short circuit, used in connection with our novel disconnect switch, is described and claimed in co-pending application Ser. No. 315,619, filed October 20, 1952.

Accordingly, it is a primary object of our invention to provide a high pressure spot contact disconnect switch of maximum short circuit capacity which is consistent with practical and economical design practice.

It is a further object of our invention to provide a novel disconnecting switch which is relatively inexpensive to construct and eliminates unnecessary brazing and milling operations.

It is a further object of our invention to provide a disconnect switch in which the contact pressure can be readily calculated and held within close limits by simple test during assembly operations.

Another object of our invention is to provide a switch construction in which the contact pressure is independent of the switch assembled and which can be readily inspected to determine contact pressure.

Still another object of our invention is to provide a disconnect switch in which stationary contact springs which carry a portion of the current, are made from high strength, high conductivity precipitation hardened alloy (such as beryllium copper) which are not subject to annealing at temperatures encountered in this type of switch.

Still a further object of our invention is to provide a simple switch construction in which contact pressure can be readily determined by checking the thickness in the contact spring spacers.

Still a further object of our invention is to provide a novel switch blade in which the contact points are spaced apart so that heat generated under short circuit conditions will be distributed over a greater area.

Still another object of our invention is to provide a novel switch blade for a disconnect switch wherein there are no constrictions in the blade to restrict the flow of heat.

A still further object of our invention is to provide cantilevered type spring contact members which are arranged to carry a portion of the-switch current as well as to supply contact pressure.

A still further object of my invention is to provide a novel switch blade for a disconnect switch in which the raised contacts therein are created by a forming operation rather than a coining operation.

These and other objects. of our invention will be ap.- parent from the following description in which:

Figure l is a side view of our novel disconnecting switch mounted on a frame and showing same in closed position with heavy-line, and in open position with dotted lines.

Figure 1a 'is an enlarged side view of the disconnect switch showing the hinge terminal, blade assembly and jaw terminal. a

Figure '2 is a top view of Figure 1.

Figure 3 is a view taken along the line 3'-3 of Figure laand-shows the engagement ofthe spherical radius contacts of the switch blade with the break tongue and the cantilevered stress on the-spring contacts. 7

Figure 4 is a view taken along the line'kd of Fig ure' la and-shows the engagement of the switch blades with the bladelatch.

Figure 5 is a top view of the switch blades used in ourswitch and illustrates the novel spherical radius contacts which are formed therein, the indentations ofblade for latching engagement with the short circuitlatch, and the-inwardly protruding cam surfaces.

Figure 6 is a side view of the switch-blade of'Figure 5.

Figure 7 is a view taken along the line 77 of Figure 6 showing the details of the spherical radius contactsand the cammed surface for separation ofthe blades by means of the pull ring.

' Figure 8 is a view taken "along the line 3' 8 of Figure 5 showing a side view of the camm'ed surfaces of the switch blade. 7

Figure 9 is-a view taken along the lines 99 of Figure 5' showing the indented upper portion of the switch blade for engagementwith the short circuiting latch,

Figure It) is a perspective view showing the jaw end of our novel disconnecting switch.

'Referring to Figure 1, the insulator units '10 and 11 are mounted on the base 12 by means of bolts 13. The upper ends of the insulator units 16 and 11 support the terminal contacts 14 and 15 which are attached thereto by means of bolts 17 and 13. The terminal connector 14 is provided with a horizontal extension 16 in which openings 17 and 18 are provided to permit connectionof the electrical'lir ie thereto.

'A verticahextension E of the terminal connector 14.

has -the hinge ends of the blades 30 and 31 rotatably n s the eqn by m ans to. pin 2-. e r inal onnector is ate t th j w nd. o e conn ng switch is provided with ahorizorital extension 33. and

34in which openingsSS and 26 are provided for proper connection to the line. i

As'best'seen in Figure 1, 1a, 3 and 10, the terminal connector 15 has a vertical extension 40 which forms the-break tongue of our novel disconnecting switch. Thev entire terminal connector 15, comprising the horizontal extensions 33 and 34 and the vertical extension 49 may be copper casting with the vertical sides of the break tongue ddmachined to obtain parallel finished surfaces.

It is necessary to machine the sides 40a and 40b of the break tongue 40:

1. So that they are parallel and have smooth surface for proper electrical engages with the spherical radius contacts.

'2. To provide a flat surface for the accurately chined spacers 44' and 45 so that the resilient spring contacts41wand 42 can be properly spaced from the parallel sides.

By' this means, an accurately predetermined consistent contact pressure can be obtained.

Sprlng :contact'arms 41 and 4.1 as best seen in Fig-..

strength, high conductivity precipitation hardened alloy such as beryllium copper which is not subject to annealing at temperatures encountered in the operation of-the disconnecting switch. As seen in the figures, thespring contacts 41 and 42 are cantilever mounted so that the contact blade will place a cantilever stress on themwhen it is closed over and touches the parallel sides of the break tongue 40.

The spacer units 44 and 45 are machined members which accurately position thespring contacts 41 and 42 to control the distance between them and the sides'40u and 49b of the break tongue 40 are machined finished to insure that these units are smooth-and parallel't'o each other.

As best'seen in Figures 3 and 10 the spring'contact members 41 and 42 are mounted by means of the bolt and nut 46-47 at their lower end so that the engagement of the knife blades 3! and 31 with the break tongue 48; as indicated, will cause a cantilevered stress to be placed on the spring contact arms. By this arrangement, highuniform consistent and predetermined'contact pressure is insured.

As seen in Figure la, 4 and 10, the break tongue 40 has a step extension 46; a short circuiting latch 50, comprising U-shaped legs 51 and 52 which straddle the step extension 49; and is attached thereto by means of connecting member 53. e short circuiting latch 50'has an'up ward extending step section 55' which serves as 'a step'or foundation for the pry out extension 81 of the pull ring as will hereinafter be more fully explained.

The short circuiting latch member 59 is also provided with a second upwardly extending portion 57 which has a latching portion 58 with a step section 59 and 6!). The;

1. Raised'contacts 7s, 74, 7s, 7s, 77, '78 of spherical radius on a. Be-75 and 76--78 on one side to engage break ns l-e40 I2. 74 and 77 on the other side to engage spring contacts '41 and v42. 7

Z. Inwardly protruding portion 94 and 95 to torrnn canimdsurface by which the blades can be separated to'enable their removal from latch engagement with a short circuited latch 53.

3., Indented upper section and 91 at the jaw end inorder to. enable the blades to belatched by the short circuited latch member 58.

As best seen in Figures 5 and 7, the contacting sur faces 73 through 78 for the switch blade are formed by providing a plurality-oi spherical radius protrusions havingapproximately a /3" radius. This spherical radius contacts are made by a forming operation on the switch blades. 30'and 31; so that no reduced cross-section or constrictions result from their formation. Thus as seen in Figures-5 and 7, the switch blade fifl is providedwith raised .contacts73 and 74 and 75. The, raised contacts 73.,and 75. protrude approximately 1 on one side of. the. blade and; the raised'contact 74 protrudes-the same distance from theopposite side of the switch blade. In

like manner the switch blade 31 is formed with raised contacts 76 77 and 78. Thus as seen-in. Figure 6,-the.

plurality of spherical radius contacts 73, 74 and 75 may be positioned in alignment with the long axis of the switch blade 30. Figure 3, which is a view taken along the line 33 of Figure la, and Figure 10 illustrates the manner in which the inwardly protruding spherical radius contacts 74 and 75 engage the break tongue 40 and the manner in which the outwardly protruding spherical radius contacts 74 and 77 engage the vertical extending spring contacts 41 and 42 respectively.

It will therefore be apparent that the engaging area of the inwardly protruding spherical radius contacts 73-75 and 76-78 are axially spaced from the outwardly protruding spherical radius contacts 74 and 77 to thereby increase the area of the switch blade which will be exposed to the low excess heating in the event of a short circuit condition. Furthermore, these contact surfaces are provided from the original material of the switch blades 30 and 31 without the necessity of reducing its cross-sectional area and thereby prevents any possibilty of heating due to any constriction of the conducting material.

As above noted, the switch blades 30 and 31 are pro vided with an inwardly extending cammed means 90 and 91 as seen in Figures 5, 7, 8 and 10. These inwardly extending cammed sections 90 and 91 are positioned to the left of the switch blade connecting studs 92 and 93 as seen in Figures 2 and 6. As will hereinafter be apparent, the cammed means 90 and 91 are provided to enable the pry out blade 81 of the pull ring 80 to wedge therebetween in order to cause a separation of the switch blade 30 and 31 to enable release from the short circuited latch 58.

As above noted, the switch blades 30 and 31 are also provided with inwardly extending indentations 94 and 95 positioned at the upper end thereof near the jaw end of the blade. As best seen in Figure 9 and 10 the indentations 94 and 95 protrude inwardly approximately and as seen in Figure 5 are positioned on the switch blade 30 and 31 between the spherical radius contacts 7578 and cammed surfaces 90 and 91. The indentations 94 and 95 are provided to enable latch engagement between the switch blade 30 and 31 and the latch means 58 as will hereinafter be more apparent.

Referring now to Figures 1, la, 2, 3 and 4 and'lO, the disconnect switch is shown in the closed position. In this position the inwardly extending indentations 94 and 95 at the upper end of the switch blade are positioned under the latching surfaces 59 and 60 of the latch means 58. In this position the lower ends 101 and 102 of the switch blade 30 and 31 are seated on the horizontal ledges 103 and 104 at the lower end of the latch unit 55. Thus it will be apparent that the blades 30 and 31 of the disconnect switch are sandwiched between the latching surfaces 59 and 60 of the latch head 58 and the horizontal ledges 103 and 104 of the latch means 55 to prevent vertical movement thereof. On the occurrence of a short circuit condition, the loop circuit created at the contact points will create an electromagnetic force to blow the switch blades upwardly. However, due to the latch engagement between the indentations 94 and 95 of the switch blades 30 and 31 with the latch surafces 59 and 60 of the latch unit 58, the disconnect switch blades 30 and 31 will remain in closed or latched position.

The manner in which the switch blades 30 and 31 are moved from the closed position of Figure l and la to the open position (indicated by the dotted lines in Figure 1) will now be described. The pull ring 80 is pivoted on the pin 92 between the switch blades 30 and 31 and is provided with a pry out extension 81 positioned between the connecting pins 92 and 93. When the operator desires to open the switch, an upward continuous pulling force is supplied to the pull ring 80 by means of a hook stick of any other desirable means. This causes counter-clockwise rotation of the pull ring 80 about its point 98 resulting in: 1

d 1. The wedging of the pry out fingers 81 between the cammed surfaces and 91 of the switch blade 30 and 31 respectively. Due to the resiliency of the blades 30 and 31, they will be separated due to the above mentioned wedging action resulting in the removal of the blade indentations 94 and from the latch surfaces 59 and 60 of latch 58.

2. The pry out finger 81 will engage the surface of the latch means 55 and thereby be prevented from further downward movement thereof.

As best seen in Figure 1, the pull ring is constructed with approximately a two to one mechanical advantage. Thus as the pry out finger 81 engages the horizontal switch 110 of the latch means 55 the pulling force on the pull ring 80 which previously resulted in mere rotation of the ring about the pivot 98, will now result in both rotation and upward movement of the pull ring 80 due to the seating of the pry out finger 81 on the horizontal flat base 110. Hence by a single continuous motion the switch blade 30 and 31 can be moved from the closed position of Figures 1 and 1a to the open position indicated by the dotted lines. Accordingly, with this novel latch and pry out mechanism, the switch blade is positively located in the closed position, and the disconnect switch may be moved to full open position with a single continuous motion of only one moving part other than blade members themselves.

Pin means 92 and 93 are positioned through the contact blades 30 and 31 to limit the movement of the pull ring 80.

Accordingly, in summary, we have provided. a novel disconnect switch to obtain high pressure point contact by providing blade members with raised contacts of spherical radius on one side to touch the break tongue and one or more raised contacts of spherical radius on the other side to touch the spring contact member where in the raised contacts are spaced apart along the axis of the blade. The raised contacts are created by a forming operation rather than a coining or dying operation and hence are created without the necessity of reducing the cross-sectional area of the blade. Thus with this novel construction for the switch blade the short circuit capacity of the disconnect switch will be materially increased due to the fact:

1. that the conducting surfaces on either side of the blade are spaced from each other.

2. that the contact surfaces are raised contacts of spherical radius with no constriction on reduced crosssectional area.

Hence with the above mentioned changes, the heat generated will be:

1. materially reduced due to the increased cross-sectional area available and raised contacts are spaced from each other.

Our novel disconnect switch provides stationary spring contact members of a precipitation hardened alloy which are cantilever from the base of the switch to replace the annealed copper fingers backed up by phosphorous bronze springs used in the prior art arrangement. Our invention also includes precision spacers positioned between the break tongue and the above mentioned spring contact members to insure a controlled distance between these two units, to enable blade members to impart a predetermined cantilever stress on the spring contact members to supply proper contact pressure.

In the foregoing, we have described our invention only in connection with preferred embodiments thereof.

Many variations and modifications of the principles of our invention within the scope of the drawings are herein obvious. Accordingly, we prefer to be bound not by the specific disclosure herein, but only by the append ing claims.

We claim: 1. In disconnect switches comprising a switch blade,

a breaktonguei spacer means and'a spring contacn'naid closed over and touching said parallel side of-said break tongue-causing a cantilevered stress on said spring contact to supply contact pressure, said spacer means con nected between said spring contact'and a parallel side of said break tongue'to accurately. govern the distance therebetwcen, said spacer-means providing an accurate predetermined distance between said parallel side of said break-tongue andwsaid spring contact to'insure a predetermined contact pressure from said cantilevered stress onsaid spring contact,

2. In a disconnecting switch having an open and closed positionucomprising a break tongue,aswitch blade and a spring contact, said break tongue being a single relativelyheavy member finished so thatthe two sides thereofi are parallel, said switch blade rotatably mounted to close over and touch a parallel side of said break tongue; said spring contact being made of a high-strength highconductivity alloy and mounted on said disconnecting switch at one end thereof, said spring contact positioned to-supply contact pressure between said switch blade and said break tongue, said switch blade being formed with a plurality of raised contacts ofzspherical radius, at. least one raised contact on one side of said switch blade to engage said fiat side of said tongue and at leastone raised contact on the opposite side of said. switchblade to engage'said contact; said plurality of .raisedcontacts permitting high: pressure spot contact between said switch blade, said tongue and said contact; said raised contacts being:formed on said. switch blade without reducing the a cross-sectional area of said switch blade to thereby preventaoverheating at any constriction therein, said raised contacts on opposite sides of said switch blade being spaced along the axis of said switch blade to further insure that heating of the contacting surfaces due to fault current will occur at widely separated points.

3. In adisconnecting switch having an open and closed position comprising a break tongue, a switch blade and a spring contact; said break tongue being a single relatively heavy member machined so that one surface thereof is flat, said switch blade rotatably mounted to close over and touch said flat side of said break tongue; said spring contact being made of a highsstrength high-con ductivity alloy, said spacer means positioned between said flat side of said. break tongue and said spring contact, 7

said spring contact being secured to said spacer means andsaid break tongue, said spacer means accurately controlling the distance between said fiat side of said break tongue andsaid'spring contact; said spring contact supplying contact pressure between said switch blade and said' break tongue, said .spacer means controlling the magnitude of said contact pressure.

4. In adisconnecting switch having an open and closed position comprising a break tongue, switch blades and stationary contacts; said break tongue being a single relatively heavy member finished so that the two sides thereof are parallel, said switch blades rotatably mounted to close over and touch said parallel'sides of said break tongue; said stationary contacts being made of a resilient position, comprising a first and second switch blade-with at hingedendand a jaw end,saidtswitch.blades-rotatablY mounted at saidhingezendand-positioned for contact engagement and disengagement at saidjaw end; a break tongue, a -pair of springcontacts, and spacermeans located. at said jaw end,-said break tongue havingparallel sides and positioned to have said-pairof blade-members close over and touch said parallel sides oi said break tongue when. said disconnecting-switch is in said closed position, said spring contacts being mounted on said spacer means andrpositionedparallel to said parallel sides of said break tongue, .said spring-contacts arranged to urge said switch blades against said parallel surfacesof said break tongue at apredeterrninedpressure, said spring contacts .postioned from said parallel surfaces by said spacer means.

6. In a disconnecting switch having'an open and closed position, comprisinga. first and second. switch blade with a hinged end and a. jaw vend, said switch blades'rotatably mounted at said hinged-.endand positioned for contact engagement sin-disengagement at said-jaw end; a tongue, a pair of spring contacts, and spacer means located at said jaw end, said tongue having parallel sides and po-- sides of Said-tongueand at least one raised contact on the opposite -side-of saidswitch blades to engage said spring contacts; said plurality of raised contacts permitting high pressure .spotcontact between said switch blades, said tongue and said spring contacts.

7..In disconnect switches comprising switch blades, a tongue, spacer means and spring contacts; said tongue being 'a single relatively heavy .member with parallel sides, said switch blades connected to close over and touch the parallel sides of said tongue, said spring contacts positioned parallel to said parallel sides of said tongue, said switchblade members when closed over and touching said parallel sides of said tongue causing cantilevered stress on. said spring contacts to supply contact pressure, said spacer means connected between said spring. contacts. and said'parallel sides of said tongue to accuratelygovern thedistance therebetwcen, said spacers providing an accurate predetermined distance between said parallel sides of said tongue and. said spring. contacts to insure a predetermined contact pressure from said cantilevered stress on said. spring contacts.

8. In disconnect switches comprising switch blades, a tongue, spacer means andcontacts; said tongue being a single relatively heavy member with parallel sides, said switch blades connected to close over and touch the parallel sides of said tongue, said contacts being made of a resilient material andpositioned parallel to said parallel sides of said tongue, said switch blade members when closed over and touching said parallel sides of said tongue causing a cantilevered stress on said contacts to supply contact pressure; said spacer means positioned to control the distance between said parallel sides of said tongue and said contacts to insure thatsaid cantilevered stress supplies apredetermined contact pressure.

ReferencesCited inithe. file of this patent UNITED STATES PATENTS 1,898,135 Massey- Feb. 21, 19.33 1,935,516 -M'u'sgrave .Nov. 14, 1933 2,157,174 Hoyej May 9, 1939 2,521,826 Caldwell et a1. Sept. 12,1950

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