US3118032A

US3118032A - Bypass disconnect type switch

Info

Publication number: US3118032A
Application number: US24753A
Authority: US
Inventors: William C Davis
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1960-04-26
Filing date: 1960-04-26
Publication date: 1964-01-14
Anticipated expiration: 1981-01-14

Description

7 Jan. 14, 1964 w c, DAVIS BYPAs DISCONNECT TYPE SWITCH sheets-sheet 1,

Filed A ril 26, 1960 In ventor: William C. Davis,

Atto'rneg.

Jan. 14, 19 4 w. CwDAVlS 3,

BYPASS DISCONNEZC'I TYPE SWITCH Filed April '26, 1960 2 Sheets-Sheet 2 Fig.5

Inventor: William C. Davis,

AttOTT'IEg.

hired This invention relates to an electric switch and has partioular application to a bypass disconnect type switch.

Where is is desired to remove an electrical device, such as a voltage regulator, from a power line without interrupting the flow of power through the line, it is customary to use a bypass disconnect switch in coniunction with the electrical device. The usual bypass disconnect switch includes two disconnect switches in series with the power line and the electrical device and one shunting switch adapted to be con. ected across the terminals of the electrical device. When the electrical device is connected in the power line, the shunting switch is in open position and the disconnect switches are in closed position, connecting opposite terminals of the electrical device into the power line. Operation of the overall switch results in first closing the shunting switch to establish a shunt around the electrical device and then opening of the disconnect switches to isolate the device from the power line.

The present invention is particularly concerned with the shunting switch and the means used for actuating the shunting switch. This shunting switch must be capable of carrying overload and short circuit currents without overheating or parting contact. The contacts of the shunting switch must remain in high pressure engagement despite the high magnetic forces resulting from these high currents.

One type of contact arrangement that has been used in other types of switches for maintaining high pressure engagement is the hairpin-type contact arrangement. This type of contact arrangement typically comprises a pair of laterally spaced U-shaped contacts that engage opposite sides of the movable switch blade. The forces of magnetic repulsion between the two arms of each U- shaped contact member force the inner arm of each contact member laterally into high presure engagement with the movable blade. in addition to these laterally acting forces, there is another force acting on the blade tending to drive the blade away from the closed ends of the lJ- shaped contact members. In most switches which use hairpin-type contacts, closing motion of the blade is in the same direction as this latter force acts, and thus this latter force tends to hold the blade in closed position. But in a typical bypass switch, closing motion of the blade is in a direction opposite to the direction which this latter force acts, and thus this latter force tends to force the blade out of closed position. Since this force increases as a direct function or current, there is a serious pro lem of holding the blade in its closed position under high current conditions.

Accordingly, an object of my invention is to construct the hairpin contacts of this latter type of switch in such a manner that there is no net magnetic force tending to drive the blade out of its closed position.

Another object is to construct the hairpin-type contact arrangement in such a manner that current flowing through the U-shaped contact members produces a magnetic force acting in a direction to drive the blade toward the closed ends of the U-shaped contact members.

in carrying out my invention in one form, I provide a switch comprising laterally-spaced contact members of U- shaped configuration. Each contact member comprises laterally inner and outer arms connected together at one end of said contact member and spaced apart at an opaten Patented Jan.

posite end in such a manner that current flowing in one direction through the outer arm of each contact member flows in an opposite direction through the inner arm so as to produce magnetic repulsion between the inner and outer arms of each contact member. The switch further comprises a switch blade movable from a disengaged position at said opposite end of said contact member toward an engaged position between the inner arms of the contact members. A stop blocks such movement of the blade when the blade has reached an engaged position spaced from said one end of the contact members. The inner arms and the blade have engaging surfaces so shaped that the force resulting from magnetic repulsion between the arms of each contact member has a bladeeating component acting on the blade in a direction to urge the blade into engagement with the stop. T current flowing through the inner arms and the blade follows a loop shape path having a magnetic effect acting in a direction to urge the blade away from the stop, but with a force less than said blade-seating component at any given current, w ereby a net magnetic force is present to maintain the blade seated against the stop.

For a better tmderstanding or" my invention, reference may be had to the following description taken in conjunction with the accompanying sheets of drawing, wherein:

FIG. 1 is a plan view of bypass disconnect switch embodying one form of my invention.

FIG. 2 is a sectional view taken along the line Z-2 of FIG. 1.

FIG. 3 is a sectional View of a portion of the switch of FIG. 2 depicting the parts of the switch during the early stages of an opening operation.

FlG. 4- is a view similar to FIG. 3 depicting the parts of the switch during a more advanced stage of an opening operation.

Fl. 5 is a plan view of the stunting switch which constitutes a portion of the overall bypass disconnect switch shown in FIGS. l-4. The shunting switch is shown in its closed position.

FIG. 6 is a sectional view taken along the line of FIG. 5.

PEG. 7 is an enlarged view of a portion of 6 depicting certain force relationships present in the illustrated contact arrangement.

Referring now to PEG. 1, there is shown a single phase bypass disconnect switch it that is used for controlling the connection between a power line and an electrical device such as a voltage regulator 14. The bypass switch comprises four spaced apart terminals 16, l N, and (2-2, to which external electrical connections can be made. Terminals l6 and 18 are respectively connected to conductors 2 i and 25 forming a part of the power line, and terminals 2t) and 22 are connected to opposite terminals of the voltage regulator 14 through conductors 2:5 and 27. When the bypass switch is in its closed position of FIG. 1, two disconnect switches 3t) and 32 forming a part of the bypass switch are in closed position and serve to connect the voltage regulator 14 in series with the power line 2d, 25. In this regard, the first disconnect switch 3% electrically interconnects terminals 16 and Zr), and the second disconnect swich 32 electrically interconnects the

terminals

22 and 18, so that the electrical circuit extends through the

successive parts

24, 16, 3i 2% 26, 14:, 27, 22, 32, 18, and 25. When the bypass switch is open, the disconnect switches fill and 32 are opened to isolate the regulator 14 from the

power line

24, 25 but not until a connection is established directly between the terminals 2-4, 25 by means of a shunting switch 35. When the overall bypass switch is in its closed position of FIG. 1, this shunting switch is open. Opening of the overall bypass switch first results in closing of the shunting switch 35, establishing a shunt around the regulator 14, and then results in opening of the disconnect switches 3t and 32 to isolate the regulator from the power line 24-, 25. This opening operation will soon be described in greater detail.

The disconnect switches 39 and 32 can be of any suitable conventional form and will therefore be described only in sufiicient detail to convey an understanding of the remainder of the bypass switch. Referring now to FIGS. 1 and 2, the disconnect switch 3b is shown as comprising a switch blade 4 pivotally mounted at its lower end on terminal structure it? by means of a hinge pin at extending through registering openings in a hinge block 43 and the blade 46. The blade 41} comprises laterally spaced segients which are biased into high pressure engagement with the hinge block 43 by means of resilient washers 41 suitably clamped against the outer sides of the segments 4-4. The hinge block 43 is supported on the terminal structure 21? and is electrically connected thereto.

At the other end of the switch blade a stationary contact finger 45 is electrically connected to the terminal 16 and projects therefrom. When the disconnect switch is closed, this stationary contact finger .5 is positioned between the segments 44. Suitable spring assemblies disposed at the outer sides of the segment id urge the segment into high pressure engagement with the stationary contact finger 45.

The disconnect switch 32; is substantially identical in construction to the disconnect switch 3b, and a detailed description of switch 32 is therefore believed to be unnecessary, particularly since like reference numerals have been used to designate corresponding parts or" the two switches. The sufiix a has been applied to the reference numerals of the switch 32.

The

terminals

16 and 18 at the upper end of the bypass switch are mounted on a slab d of insulating material so that current flowing between these terminals when the switch is closed flows through the disconnect switches 39 and 32 rather than directly between the terminals 16 and 13. Likewise, the

terminals

20 and 22 at the lower end of the switch are mounted on a slab 52 of insulating material so that current flowing between these terminals 29 and 22 when the bypass switch is closed flows through the regulator 14 rather than directly between the terminals 2% and 2.2.

The blades 40 and 4th: of the two disconnect switches are rigidly coupled together by means of a porcelain insulating post 54 and a U-shaped bracket 56 rigidly bolted together. The bracket is suitably bolted to the blade and the insulating post 54 is suitably bolted to the blade so. A centrally located lever arm 58 extending generally parallel to the switchblades 4t? and 49a is clamped between the insulating post 54 and the bracket so.

For receiving the usual hook stick that is relied upon for operating the bypass switch, an operating eye lever 69 is provided at the upper end of the switch. This operating eye lever so is pivotally mounted on lever arm 58 by means of a pin 62 extending through registering openings in the eye lever arm 6% and a bifurcated outer portion of the operating lever arm 53. When the disconnect switches and 32 are in their closed position of FIG. 2, the lever arm 58 bears against a stationary stop 64 carried at the upper end of an L-shaped bracket 66 fixed to the insulating slab 50. A hook-shaped latch es pivotally mounted on the pin 62 coaots with the stop 64 to latch the blades of the disconnect switches 3t} and 32 in their closed position of FIGS. 1 and 2. This latch 63 is biased into its latched position by means of suitable torsion spring 70.

Opening of the disconnect switches 3b and 32 is effected by pulling with a hook stick '71 on the eye lever 6 3 in a downward direction as viewed in FIGS. 24. Such action first rotates the eye lever on counterclockwise about its pivot 62 causing a stop 72 carried by the eye lever to move the latch 58 in a counterclockwise direction out of latching engagement with the stop as. Further counterclockwise motion of the eye 6i} causes a cam surface '74 on the eye to begin rolling on the top surface of the stop 64. This camming action first pries the movable blades of the disconnect switches out of their fully closed position and then drives the blades in a counterclockwise opening direction about the pivots and until they have entirely disengaged from their stationary contacts 4-5, 45a. After such disengagement, the disconnect switches 3t and 32 can be freely opened without significant opposition. rite caniming action at surface 74 continues, however, at least until the disconnect blades have completely disengaged from their stationary contacts. Because this camming action is present and because the pivot 62 of the eye lever so is located close to the stop 64 in comparison to the distance between the pivot s9 and the point at which the hook stick '71 applied force to the eye so, it will be apparent that the operator has available a relatively large mechanical advantage for driving the blades as and am of the disconnect switches out of their engaged position.

The shunting switch 35 that established a connection between the terminals 16 and 13 when the disconnect switches 39 and 32 are opened will now be described. Ref rring to PEG. 5, this shunting switch 35 comprises a pair of laterally spaced hairpin-type contact members 86 of a conductive material such as copper. Each contact member is of a U-shaped configuration and comprises a flexible inner arm 81 and an outer arm 82 joined together at their upper ends. The outer arm 32 of each hairpin contact member so is firmly bolted through a conductive spacer 33 to a stationary contact 45 or 45:: to pro vide a support for the hairpin contact and further to provide an electrical connection between the hairpin contact member and the respective terminal Zn or 22 on which it is mounted. The inner arm 81 is supported only by the outer arm 82 and is electrically insulated from its supporting terminal structure except for the connection provided by the outer arm 82.

The inner arm 81 of each hairpin contact member is adapted to be engaged by a movable shunting blade 85 which is located in a disengaged position beneath the hairpin contacts 8%? when the shunting switch is open, as shown in FIGS. l3. This shunting blade 8-5 is pivotally mounted on a stationary pivot ss carried by the bracket 66. When the overall bypass switch is operated to open the disconnect switches 30 and 32, the shunting blade 35 is driven (by means soon to be described) in a clockwise direction about its pivot E56 and upwardly into a closed position between the inner arms 81 of the laterally-spaced hairpin contacts so. FIGS. 4-7 depict the shunting blade 85 when it is in its closed position between the inner arms 31 of the hairpin contact members it.

When the shunting blade 85 is in its closed position of FIGS. 4-7, an abutment 87 at its pivoted end engages a stationary stop 89 on the bracket as. This step 89 serves during a closing operation of the shunting switch to prevent further clockwise closins motion of the blade 35 about its pivot 86. A torsion spring S t biasing the shunting blade 85 in a closing direction helps to maintain the shunting blade against the stop 39 under no load or li ht current conditions.

When the shunting switch is in its closed position, current flows therethrough by a path that extends through the

successive parts

45, 32, S1, 85', 81, 82, and 45a. In each hairpin contact, the current that flows through the outer arm $2 in one direction flows in an opposite direction through the inner arm 8-1. The magnetic repulsion resulting from current flowing in opposite directions through these adjacent conductors $1 and 32 forces the inner arm ill in a direction away from the outer arm 52 and into high pressure engagement with the sides of the shunting blade 85. The high pressure engagement afforded by the above-described magnetic repulsion is an important factor in enabling the shunting switch 35 to carry short circuit currents Without overheating or parting contact. Compression springs M. are provided betwee the

arms

81 and 82 of each hairpin contact to provide adequate contact pressure under low current conditions when the magnetic forces are low. Each of these springs 91 is suitably insulated from its contact 3% to prevent current from flowing through the spring.

In a hairpin-type contact arrangement the path followed by current in flowing through the inner arms of the two contacts and the blade disposed therebetween has a loop-shaped configuration. In the disclosed switch, this loop-shaped path is depicted by the dotted line L of FIG. 7. The magnetic eifect of such a loop-shaped path is to lengthen the loop, or more specifically to drive the blade downwardly, as shown in Fl'G. 7, away from the closed ends of the U-shaped contacts 80. This magnetic force is represented by the arrow D. In some types of switches, the presence of this magnetic force D is advantageous because it is in a direction opposite to switchopening and thus tends to hold the switch closed during short circuit conditions. But in a bypass switch such as shown, this magnetic force is in the same direction as switch-opening, and, thus, its tendency is to drive the shunting blade 85 downwardly out of closed position. This downwardly acting force varies with the square of the current flowing through the shunting switches and thus presents a serious problem as to holding the shunting blade in its closed position under short circuit condition currents.

In the disclosed switch this problem has been solved by providing cam means capable of converting the mag netic repulsion between the arms %1 and 82 of each hairpin contact 8d into a predominating force acting on the blade 53-5 in a direction opposite to the direction of the magnetic force D described in the immediately preceding paragraph. This cam means comprises a rounded projection 92 extending laterally inwardly from the inner arm 81 of each hairpin contact along substantially its entire width W. These rounded projections 92 have inner surfaces engaging the concave lateral surface 5 3 at each side of the blade 85 in the manner shown in FIGS. 6 and 7. Imaginary reference planes, each constructed tangent to these engaging surfaces at their line of engagement, are depicted at 9 n FIG. 7. It can be seen that these planes, if extended, will intersect along a line located at an end of the contact structure opposite to the closed end of the U-shaped contact members, i.e., the bottom of the contact members depicted in FIG. 7. The magnetic repulsion between the arms fill and 82 of each hairpin contact results in a force being applied to the blade along a line perpendicular to the tangential reference planes hose forces are depicted by the arrows F. Each of these forces F has a component G extending vertically upward as well as a component H extending laterally-inw/ard. The total upward force on the blade resulting from the forces G is equal to the sum of the force components G and is represented by the arrow U. This force component U is referred to hereinafter as the blade-seating force component. The projections 92. are so shaped and the

arms

81 and 82 are sul'liciently close together that the blade-seating component, or the total upward force, U exceeds the total downward force represented by the arrow D for any given current through the shunting switch 35. There is therefore a net magnetic force equal to the difference between forces U and D acting in an upward direction to hold the blade 85 firmly against its stop The ma nitude of this net magnetic force varies approximately as a direct function of the square of the current. Thus, under the heaviest short-circuit current conditions, there is no tendency for the blade to be driven downwardly out of its closed position between the contacts. The aterally-acting forces H likewise increase in magnitude as a direct function of current through the switch and thus provide higher pressures, and therefore better currentcarrying properties, under short circuit conditions.

For transmitting closing forces to the shunting blade during switch operation, a hook-shaped driving member is provided at the upper end of the overall bypass switch. This hook-shaped driving member 100 is pivotally mounted on the operating lever 58 and, hence, moves with the movable blades of the disconnect switches 3t and 32. The shunting blade 85 contains an opening through which this hook-shaped member res projects from the operating lever The upwardly projecting right hand end of this hook-shaped lever fits behind the right hand surface of a cam lever Th2, which is pivotally mounted at Th s on the stationary bracket 66. A compression spring Hi5 biases the hook-shaped member 100 in a counterclockwise direction about its pivot 107 to maintain the hook-shaped member 1% in engagement with the cam lever till while the shunting switch 35 is open. This cam lever 162, which is relied upon for transmitting closing forces from the hook-shaped driving member tee to the shunting blade 35, is positioned behind the ri ht hand surface of the shunting blade 85 and is retained between this surface and a transversely extending pin res carried by the shunting blade 85. When the blades of the disconnect switches 3d and 32 are driven in a counterclockwise opening direction, the hook-shaped driving member acts to rotate the cam member 62 in a clockwise direction about its pivot the. This clockwise motion of the cam member Th2 applies a clockwise force to the shunting blade 85 through a cam surface Ill provided on the cam member 162, thus driving the shunting blade clockwise about its pivot 86 through the intermediate position of 3 into its closed position of FIG. 4 against the stop 89. Just before the blade 85 engages the stop 89 but after the blade is fully closed, the hook-shaped member 1% moves out of engagement with the cam member Hi2, as depicted in FIG. 4, thus allowing opening of the disconnect switches 39 and 32 to continue without producing further motion of the shunting blade The engaging surfaces of the cam lever 102 and the hook-shaped member 1% are shaped like the teeth of meshing gears. in effect, the cam lever 102 is a onetooth gear pivotally mounted at Th4 and the hook-shaped nember tilt? is a one-tooth gear pivotally mounted at 42. The engaging surfaces roll smoothly on each other during closing of the shunting blade 85 and roll out of engagement just prior to the point at which the shunting blade 85 engages its stop, but after the shunting blade is fully losed. The pin it}? bears against the upper end of the hook-shaped member res during final closing motion of the shunting blade 35, forcing the hook-shaped member downwardly from behind the cam lever 162, thus preventing the spring 1:35 from defeating release of the hook'shaaed r. s'oer from the cam lever Th2.

The hook-shaped member lltlil and the cam member are so proportioned that before the disconnect switches and 32 part contact, the projections Xi. on the inner arms of the hairpin contacts St have snapped into position behind the concave surface of the shunting blade 35. This relationship will be apparent from FIG. 4, where the shunting blade 85 is shown in its fully closed position while the disconnect blade illa still engages its stationary contact 45a. This relationship provides a large margin of overlap which assures that the shunting switch 35' will be fully closed before the disconnect switches 3t! and 32 open, thus assuring that no arc will be established between the contacts of the shunting switch no matter how slowly or quickly the bypass switch is operated.

Considerable force is required in order to drive the shunting blade 85 past the projections 92 during a closing operation of the shunting switch 35 since the hairpin contacts 3%; are of a relatively he vy gauge metal and since their inner arms 31 must be displaced an appreciable distance to allow the shunting blade 85 to pass upwardly beyond the projections 92. An important factor in making this force readily available in the disclosed switch is that the shunting blade 85 is driven through its closing stroke by forces derived from the previously-described carnming action at surface 74 of the eye As was described hereinabove, this camming action and the large effective lever arm provided by the eye 6% make available to the operator a relatively large mechanical advantage for forcing the blades of the disconnect switches 30 and 32 open, and, thus, result in relatively high closing forces being applied to the shunting blade 85 in comparison to the force exerted by the operator on the eye 60. Since this camming action continues until the blades of the disconnect switches 3t and 32 are fully disengaged from their respective stationary contacts and 45a, the camming action is effective to drive the shunting blade 85 past the projections 92 and into its fully closed position. The rounded upper edges of the shunting blade also contribute to the ease with which the shunting blade is driven into its fully closed position.

Another feature which contributes in an important manner to the ease with which the shunting blade 85 is driven into its fully closed position is the fact that the cam lever 162 has a cam surface 111 on its left hand surface that engages the shunting blade This cam surface I'll is so shaped that a relatively large amount of leftward motion of the hook-shaped member Mill is required in order to produce a relatively small amount of closing motion of the shunting blade 85. Thus, the cam surface ill provides for further force multiplication and inc eased mechanical advantage with respect to forces applied to the shunting blade 35 through the hook stick 73.

Closing of the bypass switch is effected by applying to the eye 6% of the bypass switch a force that rotates the blades ll? and i ia of the disconnect switches in a clockwise direction about their pivots 42, 42a from their dotted line open position of FIG. 2. An abutment Elli) carried by the eye 6t bears against the operating lever at its outer end to transmit closing forces to the blades 46, illa of the disconnect switches 3d and 32. When the blades of the disconnect switch near their closed position, the hook-shaped member Mill enters its opening in the shunting blade 85 and moves into a position where is projecting tooth portion is beyond the cam lever 1th. and hence ready to receive this cam lever 1% when the shunting blade 35 moves to the right out of its closed position. Further closing movement of disconnect switches 3d and 32 drives the blades it) and dila into engagement with their mating stationary contacts 45 and and causes a rod 112 carried by the operating lever 53 to engage the upper surface of shunting blade 85. Further closing motion drives the blades of the disconnect switch further into engagement and causes the rod in moving downward, to push the shunting blade 85 downwardly out of its closed position. With continued closing of the disconnect switch 3i? and 32, another rod 114 carried by the operating lever 58 begins bearing against the top of the shunting blade 85 and drives the shunting blade into its fully open position shown in FIG. 1. The rod 114 holds the shunting blade 85 in this position against the bias of spring 99. The latch 63 is then seated behind the stop 64 and thereafter acts to latch the disconnect switches 30 and 322. closed and the blade 85 of the shunting switch open.

if the shunting blade 85 had been opened for any reason, such as maintenance, while the disconnect blades were open, the hook-shaped member lltlil would still seat behind the shunting blade $5 and cam lever M52 in response to closing of the disconnect blades. During such closing motion, the hook-shaped 1% would simply be forced downwardly against its spring Hi5 by the end of the cam lever 16 2 acting on the surface Hit and would snap into place behind the cam lever 19?. at the end of the closing stroke, thus restoring the overall switch lit to the condition depicted in FIG. 2.

While I have shown and described a particular embodiment of my invention it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects, and I, therefore, intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope or" my invention.

What I claim as new and desire to secured by Letters Patent of the United States is:

1. An electric switch comprising a pair of laterallyspaced contact members of U-shaped configuration, each comprising laterally-spaced inner and outer arms connected together at one end of said contact member and spaced apart at an opposite end, means including insulation between said outer and inner arms for forcing current flowing in one direction through the outer arm of each contact member to llow in an opposite direction through said inner arm so that magnetic repulsion is present between the inner and outer arms of each contact member, a switch blade movable from a disengaged position at said opposite end of said contact members toward an engaged position between the inner arms of said contact members, means for producing movement of said blade from said disengaged position toward said engaged position, stop means for blocking movement of said blade toward said one end of said contact members when said blade has reached an engaged position spaced from said one end, means including engaging surfaces on said inner arms and said blade for deriving from the force resulting from magnetic repulsion between the arms of each contact member a bladeseating component acting on said blade in a direction to urge the blade toward engagement with said stop, the current flowing through said inner arms and said blade following a loop-shaped path extending first through one of said inner arms, then through said blade, then through the other of said inner arms, said current nowing through said loop-shaped path having a magnetic effect acting in a direction to urge said blade away from said stop with a force less than said blade-seating component at any given current whereby a net magnetic force is present to maintain said blade seated against said stop.

2. The switch of claim 1 in which the engaging surfaces of said blade and said inner arms are so shaped that tangents to said surfaces at their line of engagement intersect along a line disposed at said opposite end of said contact members.

3. The switch of claim 1 in which said inner contact arms have inwardly-projecting cam portions on which the blade-engaging surfaces of said contact arms are provided, the shape of said blade-engaging surfaces being such that reference planes constructed tangent thereto along the blade-to-contact line of engagement intersect at a line disposed at said opposite end of said contact members.

4-. A bypass disconnect switch comprising first and second contacts, first and second disconnect blades mounted for movement into and out of engagement with said contacts, means including a shunting switch for elcctrically interconnecting said first and second contacts when said disconnect blades are disengaged therefrom, said shunting switch comprising third and fourth contacts respectively connected to said first and second contacts and a shunting blade movable into and out of engagement with said third and fourth contacts, means for operating said bypass disconnect switch comprising a lever pivotaliy mounted on said disconnect blades, cam means responsive to motion of said lever about its pivot on said disconnect blades for converting said pivotal motion of said lever into a diseonnect-blade-opening force acting to drive said disconnect blades out of engagement with said first and second contacts, means releasably coupling said disconnect blades to said shunting blade for driving said shunting blade into engagement with said third and fourth contacts in response to motion of said disconnect blades in a contact-disengaging direction, stop scans for blocking continued motion of said shunting blade in a contact-engaging direction at a point at which Q said disconnect blades are still in engagement with said first and second contacts and said cam means is still operative to convert pivotal motion of said lever into said disconnecr-blade-opening force.

5. The switch of claim 4 in which said releasable coupling means comprises a pivotallynnounted cam lever movable relative to said iting blade and having a cam surface bearing against sa shunting blade during contact-engaging motion of said shunting blade and further comprises a driving memb coupled to said disconnect blaes for transmitting closing icrce to said shunting blade through said cain lover, means including said cam ice for multiplying the forces transmitt d to said shun rug blade through said cam lever from said driving member, said driving member and sa; cam lever moving out of force-transmitting relationship with each other upon entry of said shunting blade into lull engagement with said third and fourth contacts.

6. A bypass disconnect switch comprising first and second contacts, first and second disconnect blades mounted for movement into and out of engagement with said contacts, means inclu ing a shunting switch for electrically interconnecting said first and second contacts when said disconnect blades are disengaged therefrom, said shunting switch comprising third and fourth contacts respectively connected to sail: first and second contacts and a shunting blade movable into and out of engagement with said third and fourth contacts, means for operating said bypass disconnect switch comprising a lever pivotally mounted on said disconnect blades, cam means responsive to motion of said lever about its pivot on said disconnect blades for converting said pivotal motion of said lever into a disconnect-blade-opening force acting to drive said disconnect blades out of engagement with said first and second contacts, means releasably coupling said disconnect blades to said shunting lade for driving said shunting blade into engagement with said third and fourth contacts in response to motion of said disconnect blades in a contact-disengaging direction, stop means for blocking continued motion of said shunting blade in a contactengaging direction at a point at which said disconnect blades are still in engagement with said first and second contacts and said cam means is still operative to convert pivotal motion of said lever into said disconnect-bladeopening force, each of said third and fourth contacts eing of a U-shaped configuration and comprising laterally-spaced inner and outer arms connected together at one end and spaced apart at an opposite end, means for forcing current flowing in one direction through the outer arm of each contact to flow in an opposite direction through said inner arm so that magnetic repulsion is present between the inner and outer arms of each contact, said shunting blade being movable from a disengaged position at said opposite end of said third and fourth contacts toward an engaged position between the inner arms of said contacts, said stop acting to block movement of said shunting blade toward said one end when said blade has reached an engaged position spaced from said one end, means including engaging surfaces on said inner arms and said shunting blade for deriving from the force resulting from magnetic repulsion between the arms of each contact a blade-seating component acting on said blade in a direction to urge the blade into engagement with said stop, the current flowing through said inner arms and said blade following a loop-shaped path having a magnetic erlect acting in a direction to urge said blade away from said stop with a force less than said blade-seating component at any given current, whereby a net magnetic force is present to maintain said blade seated against said step.

7. A bypass disconnect switch comprising first and second contacts, first and second disconnect blades mounted for movement into and out of engagement with said contacts, means including a shunting switch for electrically interconnecting said first and second contacts when said disconnect blades are disengaged therefrom, said saunting switch comprising third and fourth contacts respectively connected to said first and second contacts and a shunting blade pivotally movable into and out of a position wherein one end of said shunting blade engages said third and fourth contacts, means for pivotally supporting said shunting blade at its opposite end, means releasably coupling said disconnect blades to said pivotaliy mounted shunting blade for driving said shunt *lade into engagement with said third and fourth contacts in response to motion of said disconnect blades in a contact-disengaging direction, said releasable coupling means comprising a pivotally mounted cam lever movable relative to said shunting blade, said cam lever being pivotally mounted at one end near the pivotal support for said shunting blade and having a cam surface at an opposite end bearing against said shunting blade during contact-engaging motion of said shunting blade, said releasable coupling means further comprising a driving member coupled to said disconnect blades for transmitting closing force to said shunting blade through said cam lever, means including said cam surface for multiplying the forces transmitted to said shunting blade through said cam lever from said driving member, said driving member engaging an end of said cam lever opposite to the location of the pivotal mounting for said cam lever and moving out of force-transmitting relationship with said cam lever upon entry of said shunting blade into full engagement with said third and fourth contacts.

rug

References tilted in the file of this patent UNITED STATES PATENTS

Claims

1. AN ELECTRIC SWITCH COMPRISING A PAIR OF LATERALLYSPACED CONTACT MEMBERS OF U-SHAPED CONFIGURATION, EACH COMPRISING LATERALLY-SPACED INNER AND OUTER ARMS CONNECTED TOGETHER AT ONE END OF SAID CONTACT MEMBER AND SPACED APART AT AN OPPOSITE END, MEANS INCLUDING INSULATION BETWEEN SAID OUTER AND INNER ARMS FOR FORCING CURRENT FLOWING IN ONE DIRECTION THROUGH THE OUTER ARM OF EACH CONTACT MEMBER TO FLOW IN AN OPPOSITE DIRECTION THROUGH SAID INNER ARM SO THAT MAGNETIC REPULSION IS PRESENT BETWEEN THE INNER AND OUTER ARMS OF EACH CONTACT MEMBER, A SWITCH BLADE MOVABLE FROM A DISENGAGED POSITION AT SAID OPPOSITE END OF SAID CONTACT MEMBERS TOWARD AN ENGAGED POSITION BETWEEN THE INNER ARMS OF SAID CONTACT MEMBERS, MEANS FOR PRODUCING MOVEMENT OF SAID BLADE FROM SAID DISENGAGED POSITION TOWARD SAID ENGAGED POSITION, STOP MEANS FOR BLOCKING MOVEMENT OF SAID BLADE TOWARD SAID ONE END OF SAID CONTACT MEMBERS WHEN SAID BLADE HAS REACHED AN ENGAGED POSITION SPACED FROM SAID ONE END, MEANS INCLUDING ENGAGING SURFACES ON SAID INNER ARMS AND SAID BLADE FOR DERIVING FROM THE FORCE RESULTING FROM MAGNETIC REPULSION BETWEEN THE ARMS OF EACH CONTACT MEMBER A BLADE-SEATING COMPONENT ACTING ON SAID BLADE IN A DIRECTION TO URGE THE BLADE TOWARD ENGAGEMENT WITH SAID STOP, THE CURRENT FLOWING THROUGH