US2854553A

US2854553A - In-line jaw

Info

Publication number: US2854553A
Application number: US389099A
Authority: US
Inventors: Foti Arem
Original assignee: ITE Circuit Breaker Co
Current assignee: ITE Circuit Breaker Co
Priority date: 1953-10-29
Filing date: 1953-10-29
Publication date: 1958-09-30
Anticipated expiration: 1975-09-30

Description

A. FOTl IN-LINE JAW Sept. 30, 1958 3 Sheets-Sheet 1 Filed Oct. 29. 1953 INVENTOR. AREM Fofl A. FOTl 2,854,553

IN-LINE JAW 3 Sheets-Sheet 2 Sept. 30, 1958 Filed Oct. 29. 1953 Sept. 30, 1958 Filed Oct. 29. 1953 A. FOTl IN-LINE JAW 3 Sheets-Sheet 3 Z H w INVENTOR. AKEM Fdn United States Patent 'Cfiice ,g

lN-LINE JAW Arem Foti, Greenshurg, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa.

Application October 29, 1953, Serial No. 389,099

6 Claims. (Cl. 200-166) My present invention rel-ates to a novel high pressure contact switch wherein the current path from the operating blade to its cooperating jaw is a straight line and is more particularly directed to a novel construction for disconnect switches having a blade with both rotating and revolving motion so that the electromagnetic forces created by short circuit will be ineffective in forcing the switch blade toward the open position. i

The type of switch to which my present invention is directed is shown in copending application, Patent No. 2,673,902, issued March 30, 1954, assigned to the assignee of the instant application. This disconnect switch has an angularly rotatable contact arm which is also rotatable on its own axis. That is, the movable contact arm is initially rotated into position between the cooperating contacts and the jaw and is subsequently rotated about its own axis to thereby create a high pressure contact.

In prior art arrangements, such as that shown in the above identified copending application, the jaw member had an L-shaped configuration thereby introducing an off-set in the current path of the switch.

It has been found that the magnetic forces caused by current magnitudes of short circuit value are suflicient to either violently force the contact arm toward the open position or cause severe damage thereto. That is, since the current flowing through an ofi-set path will tend to set up a crowded magnetic field at the ofi-set, an electromagnetic force will be exerted on the conductor in such a direction as to straighten out the off-set in the current ath.

P The magnitude of system short circuit currents has been greatly increased by new generating capacity and by interconnections. A few years ago, it was thought that the short circuit current available in any outdoor station, with its relatively wide phase spacings, was sufficiently low for its effect to be neglected in station design. The engineer was very careful to obtain proper electrical clearances and proper grounding but usually neglected the effect of electromagnetic forces on conductor sizes andsupporting insulators. Until recently, this practice has resulted in outdoor stations of reasonably safe design. However, with system growth necessitating breakers of 10,000,000 kva. and 15,000,000 kva. interrupting capacity at 161 kv., serious attention must be given to the effect of electromagnetic forces. 7

It is therefore a primary object of my invention to provide a novel design for a disconnect switch which has a dual movement blade to eliminate the undesirable magnetic forces on the switch and thereby eliminate the possibility of either a faulty forceful opening or damage to the contact blade. Thus, the necessity for the in-line jaw of my invention arose from the fact that the conventional type of jaw contacts fail under heavy short circuit currents due to the fact that the stresses set up by the heavy currents in the conventional jaw with the offset current path from the blade to the jaw terminal tended to straighten out the off-set of the current path.

Dueto the oif-set in the jaw, the reaction was such that the contact blade was forced out of the jaw contacts and thereby caused failure of the jaw contacts. That is, there was severe burning at the contacting members since the switch in effect was attempting to interrupt a heavy short circuit current without the aid of arc interrupting equipment.

With the switch construction of my invention wherein the jaw member is in alignment with the contact blade, the detrimental eflfects encountered in short circuit testing of the conventional type jaw have been completely eliminated.

It will be noted that several prior art arrangements have provided in-line jaws. However, no arrangement has been adapted or applied to disconnect switches in which the blade has two degrees of movement and in which a single straight-line path for the current is provided.

My present invention is specifically directed to a novel arrangement for switches wherein the blade has both angular rotation and rotation about its own axis wherein the current path through the switch is a straight-line which is achieved by means of a horizontal jaw instead of a vertical jaw as heretofore used. The novel jaw arrangement provides a single straight-line path for the current without the necessity of an auxiliary shunt loop path.

Furthermore, my novel switch achieves the straight- 7 line current path with a horizontal jaw having a plurality of cooperating contacts wherein equalized current dis tribution on each side of the multiple contacts is achieved by varying the length of the contact spring members. In addition, my invention of a novel switch with a horizontal jaw is readily adaptable for the desirable arrangement wherein the contact blade is a substantially rigid member cooperating with a resilient jaw unit.

Accordingly, a primary object of my invention is to provide a novel switch of the type having a contact blade with angular rotation about hinge and rotation about its own axis wherein the current path through the switch is a straight-line thereby completely eliminating undesirable magnetic forces which would ordinarily tend to force the switch blade open.

A still further object of my invention is to provide a novel'horizontal jaw arrangement for a dual motion blade switch wherein detrimental effects of forces created by short circuit current can be completely eliminated.

A still further object of my invention is to provide an in-line jaw for disconnect switches which eliminates the undesirable magnetic forces created by short circuit currents wherein the jaw is a resilient member containing a plurality of contacts.

Still another object of my invention is to provide a novel construction for an electrical switch having dual blade movement wherein a single straight-line path is provided for the current flow without the necessity of any shunt or parallel loop circuit.

A still further object of my invention is to provide an in-line jaw arrangement for a disconnect switch in which equalized current distribution on each side of the multiple contacts is achieved.

These and other objects of my invention will be apparent from the following description when taken in connection with the drawings in which:

Figure 1 is a perspective view of my novel in-line jaw showing the position of the contact blade prior to switch closed position.

Figure 2 is an enlarged side view of the contact springs and contacts used in connection with my novel in-line jaw.

Figures 3a, 3b and 3c are views taken in the direction of the arrows Zia-3a, 3b-3b and 3c3c, respectively, of Figure 2 and show an end view of the contacts used in my novel in-line jaw.

Figure 4 is a side view showing my novel invention on a disconnect switch which is in closed position.

Figure 5' is a cross-sectional side view of my novel inline jaw.

Figure 6 is a view taken in-the direction of the arrows 66 of Figure 5 and Fig. 6a the position of the contact blade immediately prior to switch closed position.

Figure 7 is a schematic representation of an off-set aw.

Referring first to Figure 4, the disconnect switch 10 is mounted on the base 11 which has a'suitable longitudinal structural support, in this case shown horizontally arranged for a horizontal or upright mounted disconnect switch. The base 11' is secured thereto in any desirable manner as by

insulator spacers

12 and 13, the stationary upright supporting posts 14 and 15' on the upper portion on which are mounted insulators 16 and 17.

Belowthe insulator 23 there is keyed to the shaft 22 the crank 30' secured thereto in any suitable manner as by the bolts 31' connected to the flange or crank blade 32. Bolts 21 secure the stop plate 34 in position, the stop plate being provided at opposite ends with adjustable stops which engage at either end of the stop 38 on the operating crank 30;

A shaft 22a extends above the insulator 23 as a continuation of the vertical shaft 22 being, however, spaced therefrom by the insulator 23.

Crank 40 at the upper end of the shaft 22a is preferably integral therewith and therefore rotates therewith. Crank 40 extends horizontally or at least parallel with the base supporting structure 11 and rotates in the horizontal plane.

The outer end of crank 40 is flattened at 41 and is provided with a circular opening 42 through which pin 43 may pass. A clevis member 44 receives extension 41, the clevis being provided with appropriate openings in itsllegs to register with the opening 42 in the extension 41 of the crank 40 to thereby enable it to receive the pin 43.

The clevis 44 is integral with the threaded extension 50 which enters into an appropriate tapered opening in the forked link 52. The threaded extension 50 is so arranged so that when the threaded extension 50 rotates with respect to the forked link 52, it has linear movement with respect thereto.

A pin 60a passes through appropriate openings thereby hinging the forked link 52 to the crank 61. The blade support sleeve casting 62 carries the tubular switch blade 63 secured therein and rotatable therewith. The outer end of the tubular switch blade is flattened at 64 and is provided with appropriate contacts 65a, and 65b (Figure 6) engageable with the stationary contact jaw 66.

The blade support sleeve casting 62 is mounted for rotation about its longitudinal axis on extension of the hinge casting 70. The hinge casting 70 is in turn rotatably mounted by the hinge bearing indicated generally at 72, on the frame casting 73.

When the disconnect switch is in the closed position of Figure 4, current enters through terminal 80, passes through the frame casting 73 to the hinge bearing 72 then through the current carrying connection in the hinge hearing 72 (fully described in copending application, Serial No. 145,389, filed February 21, 1950) to the hinge casting 70 then through the current carrying connection to the contact blade 63, then through contacts 65 on the blade 63 to the contacts 90, 91, 92 and

spring contact fingers

93, 94, and 95, to the terminal 108, 109.

It will be noted that terminal 108 and its

spring contact fingers

93, 94, 95, as well as terminal 109 and its

spring contact fingers

93, 94, 95, each form the integral contactterminal members 110 and 111, respectively. Thus, it will be seen that a straight line path is provided for the current which flows from the contact blade 63 to the terminal 108, 109. The details of the in-line jaw which permits the straight line path for the current is best illustrated in Figures 1, 2 and 5.

The entire in-line jaw is supported on a casting base 102 which may be rigidly secured to the insulator 17 by means of the

bolts

103, 104. A stop member 105 is provided in the casting to serve as a fulcrum for rotation of contact blade 63 to pry out any ice or similar accumulations at the jaw contacts. However, as will hereinafter be apparent, the contact blade 62 does not mechanically or electrically engage the stop member 105 when the switch is in the normally closed position. Hence, the cast base 102 is not a conducting member since there will be no electrical connection between the contact blade 63 to this latter unit.

The base 102 extends upwardly and has a rectangular open section 106 to which the contact springs 110 and 111 can be rigidly secured.

As best seen in Figures 1 and 5, the bolts 130 are passed through the openings 131 of members 110 and 111 to secure these two members to the upwardly extending rectangular section 106 of the base 102.

The electric power line may be secured to the terminal 108, 109 of members 110 and 111, respectively, in any desirable manner, as for example by bolts passing through openings 163. Thus, current conduction will flow in the path from switch blade 63 through (1) the switch blade contacts 65a, the left contacts 90, 91 and 92 (as seen in Figure 6), to member 110 to its terminal 108, to the power line, and (2) 65a, the contacts 90, 91 and 92 (on the right), to member 111, to its terminal 109, to the power line.

The contacts 90, 91, 92 mounted on member 110 are 1 mirror images of the contacts 90, 91, 92 mounted on member 111 and hence, for the sake of simplicity, only the member 110 will be described. A side view of the contacts 90, 91, 92 is shown in Figure 2. Member 110 is provided with three extending

horizontal fingers

93, 94

and 95 of increasing length. The

slots

115 and 116 which form the three

fingers

93, 94 and 95 permit each of the fingers to flex individually and independently of' of the contacts 90, 91 and 92 are adapted to seat on their respective

spring contact fingers

93, 94 and and are permanently secured thereto by means of silver-soldering or by some other suitable means.

It will be noted that contacts 90 and 91 are provided with relatively large cut away

areas

120 and 121, respectively, so that the lower portion thereof does not engage the contact finger to which it is not attached. Thus, it will be seen that the contact 90 is secured to the spring contact finger 93 and although electrically associated with this finger, is not electrically connected to the remaining

spring contact fingers

94 and 95.

In like manner, the contact 91 is secured to and electrically associated with the spring contact finger 94 and electrically independent of the two remaining

spring contact fingers

93 and 95. Thus, the uppermost spring contact finger 94 is the shortest of the three

fingers

93, 94 and 95 and does not extend as far as the contact 91 to thereby render the contact 91 independent of the spring contact finger 93. It will be noted that equalized current distribution on each of the multiple contacts is achieved by varying the length of the

spring contact fingers

93, 94 and 95, as above described. The cut away portion 121 of the contact 91 permits this unit to be independent of the lowermost spring contact finger 95 Thus, it will be noted that the three assemblies comprising the. contact 90 and the finger 93, the contact 91 and its associated finger 94, and the contact 92 and its associated finger 95 are mechanically and electrically independent units and hence can flex individually and independently.

Each of the contacts 90, 91 and 92 is provided with a cut away

portion

124, 125 and 126 to which a silver strip may be secured to insure a good contacting surface. These

areas

124, 125 and 126 of the respective contacts 90, 91 and 92 will be engaged by the sections 65 of the contact blade 63 when the switch is in the fully closed position.

It will be noted that the stop ledge of contacts 90, 91 and 92 can be removed as there will not be an electromagnetic force lifting the blade.

Figure 6 is a view taken in the direction of the arrows 6-6 of Figure 5 indicating the manner in which the

grooves

117, 118 and 119 of the contacts 90, 91 and 92 cooperate and are secured to the respective

spring contact fingers

93, 94 and 95.

As heretofore noted, the contact blade 63 has contact portions 65a, 65b which engage the

silver strip portions

124, 125 and 126 of the contacts 90, 91 and 92, respectively.

When the switch blade 63 is in the position indicated by the upper dotted lines of Figure 6, an angular rotation in the direction of the arrows 130 is being imparted to the blade.

Figure 6a illustrates the position of the switch blade 63 after it has entered the area between the contacts prior to the time that it has been rotated about its own axis.

Immediately following the position as shown in Figure 6a, the switch blade is rotated in a clockwise direction to assume the position indicated in the solid line of Figure 6. In this position, a high pressure contact is created between the surfaces 65a, 65b and the

silver strip portions

124, 125 and 126 of the contacts 90, 91 and 92.

This position indicates the fully closed position of the switch. It will be noted in this position, the switch blade is removed from the stop member 105 by the area indicated by 135 in Figure 6. Hence, no current will be permitted to flow from the switch blade 63 to the stop 105 or the base 102. Accordingly, a single straight line path will be provided for the current flow from the switch blade 63 through the contacts 90, 91 and 92 to the

spring contact fingers

93, 94 and 95.

In the AIEE magazine Electrical Engineer for the year 1920, on page 1337, H. B. Dwight, in an article called Calculation of magnetic forces of disconnect switches, sets forth the following formula for the computation of forces on the break jaw of a disconnecting switch due to the off-set jaw and disregarding the minute electromagnetic force due to the return conductor. The following Dwight formula has been set forth and the symbols therein used are identified in Figure 7.

3 F2 1 A3 1 A; Wi n-irr an The above formula is a computation of the force in pounds resulting from a current I which will be exerted on the switch blade 63 which represents an engagement of a switch blade with a vertical jaw. It will be noted from this computation that the larger the value ofA, or the height of a vertical jaw, the greater will be the force tending to blow open the switch.

By providing an in-line jaw, as heretofore disclosed, the distance A is reduced to zero and hence the above calculation which indicates the force in pounds on the switch blade 63 shows that the force F will now be equal to zero.

Thus, it will be apparent that the only force exerted on the switch will be that minute force due to the return line. Since it is a relatively simple matter to either position the switch with respect to the return lines so that return conductor force will not create a blow open effect or to create a return line suificiently removed from the switch so that the force is relatively insignificant, it will be apparent that with my novel construction, I can novel construction wherein straightline flow is achieved .20

reduce the magnetic forces tending to open the switch due to short circuit conditions to substantially zero.

Experimental tests on the novel switch of my invention have indicated that a disconnect switch rated for a normal load current of 1200 amperes is capable of withstanding the magnetic force created by the short circuit current magnitude of 53,000 amperes whereas the prior art arrangement of a vertical jaw could not withstand magnetic forces created by currents slightly in excess of 40,000 amperes.

The similar test performed on a disconnect switch having a rating for normal load current of 2,000 amperes Was capable of withstanding periodic occurrences of magnetic forces created by a short circuit current of a 130,000

amperes whereas a comparable switch with a vertical jaw could not withstand the forces created by a short circuit current slightly in excess of 63,000 amperes.

Accordingly, it will be seen that I have invented a in a switch which has a rigid switch blade with angular rotation about its own axis and provides a jaw with a plurality of contacts which are independently and individually flexed.

In the foregoing, I have described my invention solely of. Since many variations and modifications of my invention will now be obvious to those skilled in the art,

I prefer to be bound not by the specific disclosures herein contained but only by the appended claims.

I claim:

1. In a switch having a base, a frame and a movable switch blade; said movable switch blade having a hinge and jaw end; said movable switch blade being angularly movable with respect to said frame; a current carrying connection between said frame and said movable switch blade at said hinge end of said switch blade; said movable switch blade having angular rotation about said hinge end and rotative movement about its longitudinal axis; a jaw mounted on said base at the jaw end of said movable switch blade; the longitudinal axis of said jaw being co-linear with the longitudinal axis of said movable switch blade when said blade is in closed position; said jaw comprising a rigid terminal section and a flexible blade engaging section, said terminal section and said blade engaging section being in alignment with each other and with said movable switch blade when said switch blade is in electrical engagement with said blade engaging section, the sole conducting path extending from said rigid terminal section and flexible blade engaging section to said blade, and the blade in its engaged position being in symmetrical alignment with said jaw to thereby eliminate opening magnetic forces upon said blade.

2. In a switch having a base, a frame and a movable and jaw end; said movable switch blade being angularly movable with respect to said frame; a current carrying connection between said frame and said movable switch blade at said hinge end of said switch blade; said movable switch blade having angular rotation about said-hinge end and rotative movement about its longitudinal axis; a jaw positioned on said base at the jaw end of said movable switch blade; the longitudinal axis of said jaw being co-linear with the longitudinal axis of said movable switch blade when said blade is in closed position; said jaw comprising a spring contact finger section and a terminal section; said spring contact finger section and said terminal section being in alignment with each other and extending in the direction of said movable switch blade when said blade is in closed position, the sole conducting path extending from said rigid terminal section and flexible blade engaging section to said blade, and the blade being in symmetrical alignment with said jaw to thereby eliminate undesirable short circuit magnetic forces upon said blade; a contact secured to said in ont t n e to electrically. en a di v, end.

of said movable switch bladewhen -said switchis inclosed 3. In a switch having a. base a frame and a movable switch blade; said movable switehbladehaving a hinge and jaw end; said frame: mounted on said base; said movable switch blade being angularly movable with respect to said frame; a current carrying connection between said frame and said movable switch blade at said hinge end of said switch blade; said movable switch blade having angular rotation about said hinge end and rotative movement about its longitudinal axis; a jaw mounted on said base at the jaw end of said movable switch-blade; the longitudinal axis of said jaw being co-linear with the longitudinal axis of said movable switch bladewhen said blade is in closed position; said jaw being comprised of a terminal section anda spring contact finger section; said terminal section being in alignment with said spring contact finger section and said movable switch blade; 21 supporting base secured to said jaw between said terminal section and said spring contact finger section; said supporting base being electrically isolated from said blade in its closed position, to thereby eliminate short circuit blow open magnetic forces upon said blade.

4. In a switch having a base, a frame anda movable switch blade; said movable switch blade having a hinge and jaw end; said frame mounted on said base; said movable switch blade being angularly movable with respect to said frame; a current carrying connection between said frame and said movable switch blade at said hinge end of said switch blade; said movable switch blade having angular rotation about said hinge end and rotative movement about its longitudinal axis; a jaw mounted on said base at the jaw end of said movable switch blade; the longitudinal axis ofsaid jaw being co-linear with the longitudinal axis of said movable switch blade when said blade is in closed position; said jaw comprising a plurality of spring contact fingers extending in the direction. of said movable switch blade when said blade is in closed position; a plurality of contacts; individually seated on and secured to said spring contact fingers, said contacts being in alignment in the direction of the longitudinal axis of said blade to provide longitudinal axial aiignment of said contacts and blade, the contact fingers nearest to the terminal section of said jaw having cut away portions to provide a passage for the spring contacts to extend to other of said contacts; said jaw mounted to said base by a supporting base which is electrically independent of the conducting parts of said switch; said jaw having a terminal section integral therewith; said terminal section extending in the direction of said plurality of spring con: tact fingers; the alignment of said terminal section, said spring contact fingers and said movablev switch blade rendering said switch capable of withstanding magnetic forces created by short circuit current with substantially. no blow out effect, said supporting base being secured to said jaw at a point between said terminal section and said plurality of spring contact fingers and being electrically isolated from said blade in its closed position.

5. In a switch having a base,a frame and a movable switch blade; said movable switch blade having a hinge and jaw end; said frame mounted on said base; said movable switch blade being angularly movable with respect to said frame; a current carrying connection betweensaid frame andsaid movable switch blade at said hinge end of said switch blade; said movable switch blade having angular rotation about said hinge end and rotative movement about its longitudinal axis; a jaw mounted on said base at the jaw end of said movable switch blade; the longitudinal axis ,of said jaw being co-linear with the longitudinal axis of said movable switch blade when said blade is in closed position; said jaw comprising a plurality of spring contact fingers and a terminal section both extending in the direction of saidmovable switch blade when said blade is in closed position; a plurality of contacts; individually seated on and secured to said spring contact fingers, said contacts being in alignment in the direction of the longitudinal axis of said blade to provide longitudinal axial alignment of said contacts and blade, the contact fingers nearest to the terminal section of said jaw. having cut away portions to provide a passage for thespring contacts to extend to other-of said contacts; said spring contact fingers equalizing the current distribution on each of said plurality of contacts; said jaw being positioned by a supporting baselsecured to said jaw between said terminal section and said plurality of spring contact fingers; said spring-contact fingers carrying current from said movable switch blade to said terminal section to thereby permit said supporting base to be free of current flow.

6. In a switch comprising a movable switch blade, a hinge end and a jaw end; said switch having an opened and closed position; said movable switch blade moved from said open position to said closed positionby angular rotation about said hinge and by rotation about its longitudinal axis to create high pressure contact-engagement with said jaw; the longitudinal axis of said jaw being co-linear with the longitudinal axis of said movable switch blade when said switchis closed; current carrying connection between said hinge end and said movable switch blade; said switch blade-and said jaw creating a straightline current path; said path created by saidblade and said jaw effective tominimize the blow out magnetic forces created by short circuit currents; said jawcomprising a rigid terminal section and a spring contact-fingersection, a supporting base secured to saidjaw between said terminal section and said spring contact finger section, said supporting base being electrically isolated from its blade in its.closed position, said spring contact finger section providing a straight line current path between said movable switch blade and said terminal section.

References Cited in the file of this patent UNITED STATES PATENTS 1,836,708, Dwight Dec. 15, 1931 2,316,844 Cornell et al. Apr. 20, 1943 2,328,171 Schwager Aug. 31, 1943