US3319032A

US3319032A - Irreversible electric switch

Info

Publication number: US3319032A
Application number: US422162A
Authority: US
Inventors: Leslie L Baird
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1964-12-30
Filing date: 1964-12-30
Publication date: 1967-05-09
Anticipated expiration: 1984-05-09

Description

y 9, 1967 L, BAIRD 3,319,032

IRREVERSIBLE ELECTRIC SWITCH F/GJ.

INVENTOR. LssL/s L. 67mm 5) W MM May 9, 1967 L. L. BAIRD IRREVERSIBLE ELECTRIC SWITCH 4 Sheets-Sheet 2 Filed Dec. 30, 1964 INVENTOR LESLIE L.5 /R0,

5 (1mm S. W Arm May 9, 1967 L. L. BAIRD 3,319,032

IRREVERS-IBLE ELECTR IC SWITCH Filed Dec. 30, 1964 4 Sheets-Sheet 3 1026! ATO A17 2J0 A42 (Ara 1: 20

INVENTOR. LEsL/E L. Bm/w,

A T TOR/V5 Y 4 Sheets-Sheet 4 Filed Dec. 30, 1964 //v VENTOR LEsL/ E L. BA/RD,

United States Patent 3,319,032 IRREVERSIBLE ELECTRIC SWITCH Lesiie L. Baird, Swarthmore, Pa., assignor to General Electric Company, a corporation of New York Filed Dec. 30, 1964, Ser. No. 422,162 8 Claims. (Cl. 200-153) This invention relates to electric switches, and more particularly it relates to a manually operated switch having movable contacts that cannot be reversed on movement from open to closed positions.

The present invention has special utility in relatively high current (e.g. 1,200 amperes), 600-volt service entrance applications where multipole fused switches with bolted-pressure contacts are commonly used to switch and to protect A.-C. electric power circuits and loads fed from service entrance conductors. In practice such devices are equipped with low-cost manually or electrically operated mechanisms for opening the main switch contacts when desired, thereby breaking the circuit in which the device is connected and interrupting whatever load current may then be flowing. Overload and fault protection is automatically provided by the electric fuses which are designed to blow under overcurrent conditions with a time delay inversely related to overcurrent magnitude. By using class L (NEMA standards designation) lowvoltage current-limiting cartridge fuses, current as highvas 200,000 amperes can be quickly and safely interrupted in the event that a very severe fault or short circuit occurs.

Sometimes an overload or short circuit condition will pre-exist in the protected circuit when a service entrance switch is being closed, in which case current of high magnitude begins to flow when the circuit-making contacts of the switch first touch. The magnetic forces that are associated with this fault current will oppose closing and may be strong enough to blow the switch contacts apart, thereby endangering the operator who is actuating the manual closing handle of the switch. And the operator, on becoming aware of this condition, is likely to hesitate or to attempt to quickly reopen the switch. In such circumstances it has heretofore been possible, in commercially available manually-closed service entrance switches, to tease the contacts-that is, it has been possible for the contacts to be alternately parted and engaged as the closing operation falterswith resulting sparking and damage to the contacts as well as potential injury to the operator.

If the magnitude of the above-mentioned fault current is not suificiently high to cause earlier blowing of the fuses, the operator may be able to separate the circuitmaking contacts of the switch While substantial overcurrent (eg. 6 times rated full-load current) is being conducted. Consequently, the interrupting capacity of the switch contacts should be coordinated with the fuse characteristics and with an assumed minimum time for opening the switch so that the contacts are able safely to interrupt at least this expected amount of excess current.

One object of the present invention is the provision of a switch having improved safety features for service entrance applications and the like.

Another object of the invention is the provision of a manually closed switch having relatively inexpensive means for positively preventing any kickback on the closing handle when the switch is being initially closed in a severely short-circuited electric power circuit.

Yet another object of my invention is to provide a switch having relatively inexpensive means for positively preventing backtracking of the manual operating handle and the movable switch contacts by the operator during the course of closing the switch.

A further object of my invention is to provide a relatively simple and inexpensive manually closed switch which cannot be opened prematurely by the operator once the circuit-making switch contacts touch.

In carrying out my invention in one form, a dead-front fusible switch is provided with a manual operating handle and a mechanism for safely closing or opening the switch without exeltion of untoward force by the operator. The mechanism is connected to a movable switch member which is adapted to support an electric contact. Opera-tion of the mechanism causes the switch member to move between a predetermined first position, in which the supported contact is separated from a cooperating, relatively stationary contact of the switch, and a predetermined second position in which the supported contact is in engagement with the stationary contact. In combination with the switch member I provide means effective on movement of the member from its first position in the direction of the second position for preventing any appreciable reverse movement thereof before the member reaches its second position. Hence the switch member cannot be prematurely moved in the reverse direction toward its first position by the operator, and it cannot be blown in that direction by magnetic forces associated with any fault current the contacts may conduct when they first touch. As a result, teasing of the contacts is prevented, the assumed minimum opening time of the switch is assured, and the high forces of reaction associated with fault current conduction will not be transmitted to the manual operating handle. The reversemovement-preventing means is arranged to be disabled on further movement of the switch member beyond its second position, whereby subsequent opening of the switch is permitted.

My invention will be better understood and its various objects and advantages will be more fully appreciated from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a front elevation of a 3-pole electric switch embodying my invention.

FIG. 2 is a side elevation of the FIG. 1 switch in an open circuit condition, with portions of the front and the back frames of the switch broken away to more clearly show its interior parts;

FIG. 3 is a partial front elevation of the switch shown in FIG. 2 after the front frame and its associated parts as well as the arc-quenching means have been removed;

FIG. 4 is a side elevation similar to FIG. 2 but with the movable switch member shown in its closed position;

FIG. 5 is an enlarged sectional view taken through lines 55 of FIG. 4; and

FIG. 6 is a side elevation of the parts shown in FIG. 5 in the positions they assume during a switch closing operatron.

Referring to FIGS. 1 and 2, the illustrated switch will be seen to include a stationary unit 11, three pairs of spaced-apart incoming and outgoing electric

current conductors

30 and 40 fixedly supported by the unit 11 in side-by-side relation to each other, and a carriage 101 adapted to support means for closing and opening a circuit between the separate conductors forming each

pair

30, 40. The carriage 101 also contains a mechanism for conjointly actuating all three of the circuit closing and opening means, and this mechanism includes a manual operating handle 120 that is accessible from the front side of the carriage escutcheon 110. The handle 120 is pivotally movable between a vertical, switch open position shown in solid lines in FIG. 1 and a raised, switch closed position shown in broken lines.

The entire switch assembly is adapted to be mounted in any suitable enclosure having an openable front cover for access, with the unit 11 being bolted or otherwise secured to the enclosure and the escutcheon and the handle 120 protruding through a conforming aperture provided in the cover. The operating handle 120 in its raised position would prevent opening of the cover, thereby blocking access to the interior of the enclosure so long as the switch is closed.

The construction ofthe stationary unit 11 of the switch will now be described. This unit includes a back frame having generally L-shaped metal side structures that are rigidly fastened together by a plurality of cross pieces. As is best seen in FIG. 2, each of the side structures comprises an angle disposed vertically to form a rear corner post 12 and bent horizontally to form a side member 13 extending frontwardly from the lower end of the post 12. At the front end of the member 13 a relatively short upstanding plate 14 is affixed, and this plate is additionally fastened to the midsection of the post 12 by means of a diagonal brace 15. A notch 16, bounded by a horizontal upper lip 14a and a vertical lower lip 14b, is provided in the frontside of the plate 14 for removably receiving and holding a support pin 116 of the carriage 161.

At -a point 17 on the rear section of the side member 13 there is pivotally mounted an upstanding support and locking member 18. This member is spring biased to a position in which a corner 18a thereof bottoms on the horizontal flange of the side member 13 and in which an anchor pin 18b carried by the member 18 is disposed directly above the corner 18a as shown. The side member 13 is joined to the corresponding member on the far side of the stationary unit by a bar 19 that extends across the bottom of the unit, and the two corner posts 12 are spanned at different elevations by two

horizontal channels

20 and 21 that are tightly bolted to the backsides thereof. The

channels

20 and 21 are made of rigid, electrical insulating material.

The stationary unit 11 also includes a plurality of separate pairs of spaced-apart relatively stationary

electric contacts

31 and 41, which pairs are mounted in side-byside relation to each other on the

insulating channels

20 and 21 of the frame described above. A front view to one pair of contacts is shown in FIG. 3 (and the other pairs are essentially the same). It will there be seen that the

contacts

31 and 41 are of jaw-like design, that is, each one comprises a pair of electrically interconnected, physically spaced electroconductive elements or

contacts

32 and 33 arranged to grip opposite sides of a movable blade-like contact inserted in the gap therebetween. The

contacts

32 and 33 preferably comprise defiectable silver plated copper bars having their fiat side in parallel ver-.

tical planes that are perpendicular to the channels 21 and 22 and having their forwardedges beveled to guide the cooperating blade on its insertion therein.

Adjoining the outer side of the bar 32 of the lower stationary contact 41 is a dished member 34 that is rigidly fastened to the associated channel 21. The bar 32 is affixed to this member. A depending portion of the bar 32 is connected to and supports the aforesaid conductor 40 in a convenient disposition for connection to an external electric power circuit, and a similar portion of the companion bar 33 is also attached to the conductor 40. The

bars

32 and 33 extend vertically from the conductor 40 in spaced parallel relation to each other, and another dished member 37 is located on the outer side of bar 33 opposite the member 34 as shown. At one point between the bars 32 and 33 a suitable spacer 38 is disposed for the purpose of maintaining between the inner sides of the bars at this point a predetermined minimum gap whose length is approximately the same as the thickness of the blade to be inserted.

In order to ensure a tight yet separable connection between the

bars

32 and 33 and the blade that is inserted therebetween, suitable pressure applying clamping means is provided. As shown in the drawings this clamping means includes a common rotatable drive shaft 60 extending horizontally through aligned apertures in the

respective bars

32, 33 and

members

34, 37 that comprise preferably comprises an externally threaded tubular bolt that can be rotated with respect to the nut 63 by predetermined rotation of the shaft 60. The bolt head is located in the dished member 34, and the bolt extends along the shaft into the member 37 where it mates with the nut 63. Thus the head of the bolt 62 and the nut 63 respectively bear against opposite sides of the stationary jaw-like contacts, and the cooperating blade-like contact can be tightly clamped between the

bars

32 and 33 by rotating the shaft 60 so as to turn the bolt into the nut. I

This bolted pressure arrangement will be further described hereinafter.

The construction of each upper contact 31 of the stationary unit 11 is similar to that described above for the lower contact 41. However, the spaced bars 32 and 33 forming each of the jaw-like contacts 31 extend upwardly instead of downwardly from the associated members 3 1 and 37 to the attached conductor 31? with each member 34 being rigidly fastened (by the means shown at 33 in FIG. 2) to the upper insulating channel 20 instead of to i the lower one.

It is now apparent that by electrically interconnecting the paired

contacts

31 and 41, a closed electric circuit will be formed between corresponding upper and

lower conductors

30 and 40, and for this purpose a bridge-like electroconductive element 231 having blade-like main contacts 201a and 211112 at opposite ends thereof is provided. The element 261, which is shown in phantom in FIG. 3, is supported in a manner hereinafter fully described by a movable switch member on the aforesaid carriage 101. When its contacts 201a and 2011) are inserted between the jaw-like contacts 32-33 of 31 and 41, the element 201 completes a main current path between

conductors

30 and 40. High-pressure, low-resistance connections between these cooperating main contacts is then obtained by actuating the above-described clamping means.

The common drive shaft 611 of the clamping means associated with the respective upper contacts 31 and the corresponding drive shaft 60 below have been interconnected for joint rotation by a pair of tie bars 6 The upper ends of the tie bars 64 are pivotally attached at 65a to a pair of cranks 65 that are respectively keyed to opposite ends of the upper shaft; the lower ends of these bars are pivotally attached at 66a to a pair of cranks 66 keyed to opposite ends of the lower shaft. Both of the shafts 60 are biased in a pressure relieving direction (counter clockwise as viewed in FIG. 2) by means of a pair of springs 67 each of which is connected in tension between one of the tie bars 64 and the adjacent corner post 12 of the stationary unit so as to urge the bar upwardly. Both shafts are simultaneously rotated in the opposite, pressure-applying direction by actuating means located on the carriage 1101, soon to be described.

Each of the upper relatively stationary contacts 31 also includes a pair of jaw-

like arcing contacts

42 and 43. These arcing contacts comprise elongated, relatively thin metal members disposed between the

bars

32 and 33 adjacent to the main contact area thereof. The upper ends of the

members

42 and 43 are physically and electrically connected to the stationary bar 32 by a bolt 44 or other suitable means. The lower portions of the

members

42 and 43 are bent to protrude in front of the bar 32 (best seen in FIG. 4), where they form a relatively short gap in alignment with the gap between the bars 32 and 33 (best seen in FIG. 3). The

tips

42a and 43a of the protruding portions of these members are turned up to form are runners.

The protruding portions of each pair of relatively

stationary arcing contacts

42 and 43 are arranged to be separably engaged by a blade-like arcing contact 202 that is mounted on the movable switch member of the carriage 101 in association with the main contact 201a of each of the bridge-like elements 201. When the element 201 is in a closed circuit position (FIG. 4), its arcing contact 202 is disposed between the cooperating arcing

contacts

42 and 43 which yieldably grip opposite sides of the contact 202 to maintain a good electrical connection therewith. During movement of the element 201 toward an open circuit position, the arcing

contacts

202 and 42, 43 will not separate until after the

main contacts

201a and 32, 33 are disengaged, whereupon an electric arc may be drawn between the arcing contacts. Any such arc will be contained and extinguished within an electric arc chute '50 that embraces the protruding portions of each pair of the

stationary arcing contacts

42 and 43.

As is seen in FIGS. 1 and 2, a clamp 51 and a pair of long bolts 52 are used for removably securing a separate are chute 50 to the stationary unit 11 in association with each of the contacts 31. The bolts 52 are anchored in a horizontally-extending strip 53 of insulating material that in turn is rigidly fastened to the front sides of the respective members 34 of the stationary contacts 31. Since neither the presence of the arc chutes 50, their design particulars, nor the method of mounting the chutes on the stationary unit 11 are material to the present invention, a detailed description of these parts will be omitted.

The construction of the carriage 101 of the switch will now be described. It comprises a metal front frame having generally L-shaped side structures that are rigidly fastened together by a plurality of cross pieces. Each of the sidestructures of this frame comprises an angle forming a vertical front corner post 102, a side plate 103 atfixed to the post 102 near its lower end and extending rearwardly therefrom, and a diagonal brace 104 interconnecting the rear end of plate 103 and the upper end of post 102. A shaft 105 extends horizontally across the bottom of the carriage and is journaled at its opposite ends to the respective side plates 103, and two

rigid cross members

106 and 107 span the corner posts 102 to complete the frame. The escutcheon 110 is bolted at 111 to the

cross members

106 and 107 of the front frame as shown. This frame, in combination with a switch member 203 that is movably supported thereby and a mechanism for moving the same, comprises a portable unit that is separably hinged to the stationary unit 11 for angular movement between two different positions.

For the purpose of separably hinging the portable unit on the stationary unit, a coaxial pair of laterally projecting support pins 116 are respectively located on the opposite side plates 103 of the carriage 101 in the vicinity of the front side thereof. These pins fit into the aforesaid notches 16 in the upstanding plates 14 of the stationary frame, and the carriage 101 can pivot or swing about the common axis of these pins to and away from a predetermined first or operating position in which it is shown in FIGS. 1, 2, and 4. This position is dete mined by the anchor pin 18b abutting the top edge of a slot 118 formed in the bottom of each side plate 103 of the carriage as shown. So long as the carriage 101 is in the operating position, the upper lip 14a of each notch 16 overhang-s another pin 117 located next to each support pin 116 (see FIGS. 1 and 2) to prevent lifting the portable unit vertically with respect to the stationary unit 11.

From its first position the portable unit can be pivoted on its support pins 116 through an angle of about 75 or 80 degrees to a second or tilted position which is determined by an appendage on each of the corner posts 102 abutting the under side of a stop pin 15a that is affixed to each of the diagonal braces 15 of the stationary unit.

From its tilted position the portable unit can be separated from the stationary unit for installation and servicing convenience by manually lifting it so that the pins 116 leave the notches 16, for which purpose a C-shaped carrying handle 108 is prominently located on the upper cross member 106 of the carriage 101.

The portable unit includes the switch member 203 which is adapted to support the aforesaid bridge-like electroconductive elements 201. The switch member 203 is pivotally mounted on the side plates 103 of the carriage 101 for reciprocal movement relative thereto between predetermined closed and open positions. The switch member is a channel of rigid insulating material extending horizontally across the carriage between a pair of attached metal brackets or legs 204 that are supported by a coaxially pair of pivot pins 119 projecting laterally from the respective side plates 103 in the vicinity of the back side of the carriage. With the portable unit in its aforesaid first position, the pivot pins 119 are about coaxial with the lower rotatable shaft 60 of the previously described contact clamping means. The axes of the pivot pins 119, the support pins 116, and the shaft are all oriented parallel to each other.

The electroconductive element 201 supported by the switch member 203 is shown in FIG. 2 as a cartridge fuse having vertically oriented blade-like terminals that comprise the aforesaid main contacts 201a and 201b, respectively. Three separate fuses are removably supported by the switch member in side-by-side electrically insulated relation to each other, each fuse being located adjacent to the back side of the carriage with its terminals aligned with a corresponding pair of relatively stationary jaw-

like contacts

31 and 41. Toward this end the member 203 is provided with a plurality of spaced-apart pairs of

fuse holders

205 and 206 arranged to hold opposite terminals 201a and 20112 of the respective fuses 201.

Each of the lower fuse terminal holders 206 is in the form of a generally rectangular collar projecting rearwardly from the bottom of the switch member 203, to which it is affixed, and a relatively thin U-shaped bracket subtending the collar. The blade-like fuse terminal 201b is loosely embraced by the collar, which restricts lateral movement of the blade, and it is supported by the interior surfaces of the bracket which limit edgewise movement thereof. The bracket is made thinner than the blade 20112 so as to avoid interfering with the direct electrical connection between the blade and the jaw-like contact 41.

Each of the upper fuse terminal holders 205 is in the form of an inverted L-shaped metal member that comprises the aforesaid arcing contact 202. This contact has one end 202a pivotally attached to an upright bracket 207 that is affixed to the top of the switch member 203, and its other end is integrally connected to a pair of parallel, spaced-apart arms 205a whose free ends are releasably bolted to the switch member 203. The arms 205a loosely embrace the blade-like fuse terminal 201a and hence restrict lateral movement of the blade. The side of contact 202 adjoining the arms 205a is adapted to abut the leading edge of the blade 201a as shown, and contact pressure is there maintained by a spring-loaded plunger 210 that urges the blade away from the switch member 203. The arcing contact 202 is made thinner than the blade 201a so as to avoid interfering with a direct electrical connection between the blade and the main jaw-like contact 31.

By unfastening the arms 205a from the switch member 203, the upper fuse terminal holder 205 can be pivoted about 202a to a position wherein the arcing contact 202 is disengaged from the blade 201a, whereby the fuse 201 is released from the switch member for removal and replacement purposes. This operation is most conveniently accomplished while the carriage 101 is in its tilted position described hereinbefore.

The switch member 203 of the portable unit is moved between its open and closed positions by an operating mechanism that will next be described. The operating nechanism in its preferred form includes the manual oper-' rting handle 120. As can be seen in FIGS. 1 and 2, hanile 120 depends radially from the front end of a short iorizontal shaft 121 to which it is affixed. The shaft 121 extends through the escutcheson 110 and is journaled near its rear end in a bearing 122 that is centrally supported by the upper cross member 106 of the carriage 101. A platelike crank 123 is keyed to therear end of the shaft 121.

The plate 123 is drivingly connected to the rotatable shaft 105 of the switch operating mechanism by means of a tie rod 124. A pin 123a protruding rearwardly from the plate 123is loosely embraced by an eyelet formed at the upper end of the tie rod 124. The lower end of this rod is pivotally attached to a pin 125a spanning a yoke 125 that is pivotally supported at the distal end of an arm 120 projecting radially from acentral portion of the shaft 105 to which it is rigidly anchored, whereby a universaljoint is formed between the tie rod 124 and the arm 126. With this arrangement, the shaft 105 is rotated approximately 45 degrees in a clockwise direction (as viewed from the right side of the switch) in response to the operating handle. 120 being pivoted counterclockwise (front view) about the axis of the shaft 121 from its vertical position shown in FIGS. 1 and 2 through an angle of approximately 135 degrees to its fully raised position. If desired, the shaft 105 could alternatively be driven by other suitable means, such as a stored energy spring-actuated mechanism.

It is desirable to releasably lock the manual operating handle 120 in each of its vertical and raised positions, for which purpose a spring loaded plunger 112 is mounted on the upper cross member 106 behind theescrutcheon 110. Whenever the handle is in its vertical (open) position, which position is defined by a first shoulder 12311 of the plate 123 engaging a boss 10611 on the cross member 106, the plunger 112 is spring-biased rearwardly into a cooperating notch 123a provided in the edge of plate 123, whereby counterclockwise movement of the plate is blocked until the plunger is withdrawn by pulling a knob 11 3 that is attached thereto. The knob 113 is accessible from the front side of the escutcheon 110. When the knob is pulled and counterclockwise movement of the operating handle 120 is begun, the front surface of the plate 123 slides across the end of the plunger 112. As the handle reaches its fully raised (closed) position, which position is defined by an opposing shoulder 123d of the plate 123 engaging the same boss 106a, the first shoulder 123b will move just beyond the plunger 112 which isthen free to move rearwardly into a blocking position therewith, whereby reverse movement of the handle .120 in a clockwise direction is physically prevented until plate 123 is again released by manually pulling the knob 113.

The driven shaft 105, as was mentioned hereinbefore, extends horizontally across the carriage 101 and is journaled at its opposite ends to the respective side plates 103. A pair of cam members 127 are keyed to the shaft 105 near its respective ends. The preferred configuration of each cam member 127 is best seen in FIG. 2. Each is provided with a cam slot 128 having a generally vertical section 128a that intersects and extends downwardly from the rear end of a generally horizontal section 1281). A roller 204a is disposed in the cam slot 128. The roller 204a is mounted on the supporting leg 204 of the movable switch member 203, and it traverses the cam slot 128 during closing and opening operations of the switch operating mechanism.

The action of the mechanism during a closing operation will now be considered.

The switch closing operation is accomplished in two distinct steps. The first step is carried out by releasing and angularly moving the manual operating handle 120 through about one-half of its 135-degree counterclockwise closing stroke. This will cause the arm 126 on the shaft 105 to move through approximately three-fifths of its 45-degree throw, thereby rotating the shaft 105 and its cam members 127 a corresponding amount. During this step the front edge of the first section 128a of the cam 510114128 moves rearwardly and earns the roller 204a upwardly with respect thereto. As a result, the rollers 204a, the legs 204, and hence the switch member 203 are driven clockwise on the pivot pins 119 along an approximately 42-degree arcuate course from the initial open position shown in FIG. 2 to the closed position in which these parts are shown in FIG. 4. The clockwise movement of the switch member 203 carries the blade-like upper terminals 201a of the respective cartridge fuses 201 into wiping engagement with the associated jaw-like stationary contacts 31.

For the remainder of the closing operation, the roller 204a will be in the second cam slot section 1281) whose bottom edge closely conforms to the arc of a circle concentric with the shaft 105, whereby the movable switch I member 203 is held in its closed position but no further clockwise angular motion is imparted thereto.

With the fuse-carrying switch member 203 in its closed position, and with the carriage 101 fixed in its operating position shown in FIG. 4, the terminals at the opposite ends of each cartridge fuse 201 directly engage both of the main

stationary contacts

31 and 41 that are associated therewith, thereby making or completing a fused electric circuit between corresponding upper and

lower conductors

30 and 40. For the purpose of positively anchoring the portable carriage 101 in its aforesaid disposition to the stationary unit 11 while the switch is being closed, each cam member 127 has been provided with a lobe 127a whose leading edge engages a roller 18c mounted on the adjacent support and locking member 18 so as to tilt this member counterclockwise upon initial clockwise rotation of the cam member 127. When so tilted, the anchor pin 18b carried by the member 18 shifts frontwardly from the mouth to an interior portion of the notch 118 that is formed in the bottom edge of the side plate 103 of the carriage 101. The carriage 101 is then locked to the stationary unit 11, and it cannot be moved relative thereto until the side plate 103 is subsequently released by egress of the pin 1811 from the notch 118 when the cam member 127 returns to its original position. This prevents the hazardous possibility of opening the switch contacts by tilting the carriage.

The second step of the switch closing operation is used to actuate the above-described contact clamping means so as to apply high contact pressure on the then interengaging main contacts of the switch. This step is carried out by continuing to move the manual operating handle 120 through the remainder of its counterclockwise closing stroke to its fully raised position, thereby causing the shaft and its cam members 127 to turn clockwise from the position shown in FIG. 4. If desired, spring means (not shown) could be coupled to the handle so as to assist the operator in moving the handle during this part of its closing stroke,

With the cam member 127 in its FIG. 4 position, a camrning surface 139 on the rear edge thereof engages a roller 260 mounted at one end of a coupling lever 261 whose opposite end 262 is slotted. The axle of the roller 260 protrudes a short distance in the direction of the lower stationary contact 41 which is adjacent thereto. At a point midway between the roller 260 and the slot 262, the lever 261 is journaled on the pivot pin 119 which projects laterally from the side plate 103 of the carriage 101. A tension spring 263 (see FIG. 2) biases this lever in a counterclockwise sense to a normal position determined by a boss on the lever engaging the side plate 103.

With the lever 261 in its normal position and with the carriage 101 anchored in the fixed disposition shown in FIG. 4, the slot 262 will register with a pin 6611 protruding from the crank 66 that is keyed to the adjacent end of the lower rotatable shaft 60 as previously described. (The lower shaft 60 is coaxial with the 9 pivot pin 119.) The crank 66 is also provided with a slot diametrically opposite the pin 66b, which slot registers with the protruding axle of the roller 260. Thus the crank 66 is coupled to the lever 261 for joint rotation therewith. The same coupling is provided at the far side of the switch.

As the second step of the switch closing operation is carried out, the camming edge 129 of the member 127 advances in such a manner as to drive the roller 260 and hence the lever 261 clockwise about the pivot pin 119 through an angle of approximately 45 degrees. The crank 66, being coupled to the lever 261, is correspondingly rotated with respect to the axis of the lower shaft 60, and the interconnected upper crank 65 is rotated conjointly therewith. As a result, each of the upper and lower drive shafts 60 of the contact clamping means is turned clockwise about its axis from the initial angular position in which it is shown in FIGS. 24 to a predetermined final angular position spaced from the initial position by approximately 45 degrees. During the course of this turning each tubular bolt 62 is screwed into the associated nut 63, thereby reducing the spacing between the bolt head and the nut and compressing the interposed

contact members

32, 33 and 2010 (or 20112). This contact clamping action is more fully explained above in connectionwith the description of FIG. 3.

The second step of the switch closing operation is completed when the manual operating handle 120 reaches its fully raised position (shown in broken lines in FIGS. 1 and 4) where it is retained by the releasable locking means 112, 113 previously described. Brief consideration will now be given to a switch opening operation, which is essentially the reverse of the closing operation just described.

The switch opening operation is begun by releasing the operating handle 120 and angularly moving it in a clockwise direction (front view), thereby causing counterclockwise rotation (as viewed in FIG. 4) of the shaft 105 and its cam members 127. The illustrated cam member 127 is provided with a hook-like part opposing the camming edge 129, and a camming edge 129a on this part pulis the roller 260 and hence the lever 261 and the crank 66 in a counterclockwise direction. This action, which is aided by the springs 67 and 263, simultaneously turns both of the drive shafts 60 of the contact clamping means in a counterclockwise, pressure relieving direction. As the rear end of the second cam slot section 1281) in the member 127 approaches the roller 204a, the coupling lever 261 returns to its normal position shown in FIG. 4 and each drive shaft 60 is returned to its initial angular position, whereby the bolted-pressure connections between

stationary contacts

31, 41 and fuse terminals 201a, 2011) are loosened before the movable switch member 203 is moved away from its closed position.

Continued counterclockwise rotation of the cam member 127 after the rear edge of its first cam slot section 128a makes contact with the roller 204w will cam the roller downwardly with respect thereto. As a result, the switch member 203 and supporting legs 204 are moved counterclockwise on the pivot pins 119 along their predetermined arcuate course from closed to open positions. This reverse movement of the switch member 203 effects separation of the upper-fuse terminal 201a and its associated arcing contact 202. from the stationary contact 31, and consequently the electric circuit between the corresponding upper and

lower conductors

30 and 40 is opened.

The switch opening operation is completed when the manual operating handle 120 reaches a vertical position (FIG. 2) where it is again retained by the releasable locking means 112, 113.

As the movable switch member 203 is returning to its open position near the end of the switch-opening operation, the lobe 127a on the cam member 127 moves beyond the roller 180 on the support and locking member 18, and the rear edge of the lobe will engage and move a laterally-protruding pin 18d on the member 18. This tilts the whole member 18 clockwise to a position in which the anchor pin 18b registers with the mouth of the notch 118 in the side plate 103 of the carriage 101, thereby disabling the anchoring means and releasing the carriage 101 for angular movement on its support pins 116 from the position shown in FIG. 2 to the tilted position mentioned hereinbefore.

In accordance with my invention, the movable switch member 203 has been equipped with means for ensuring irreversible motion between its Open and closed positions. This means, which is independent of the switch operating mechanism previously described, preferably comprises at each side of the switch an elongated element 250 atfixed to the switch member 203 and a tiltable locking element pivotally attached to a laterally protruding pin 102w on the front corner post 102 of the frame of the carriage 101. As is apparent in FIGS. 2

and 4, the elongated element 25-0 is part of the switch member supporting leg 204, and its longitudinal centerline is oriented generally parallel to the arcuate course of movement of the switch member.

Each locking element 150, best seen in FIG. 5, comprises two parallel links spanned by a pair of spacedapart

transverse pins

151 and 152. The elongated element 250 extends through the gap bounded by these links and pins. As is best seen in FIG. 6, the locking element 150 is disposed in a slightly tilted disposition on the element 250 so that the

pins

151 and 152 frictionally engage opposite sides of the element 250 on opposite sides of a plane P perpendicular to its longitudinal centerline C. The pins 151 and 152 will move obliquely with respect to the centerline C as the element 150 is moved from this disposition, and in order to permit the element 150 to be pivoted to another disposition (in which it is shown in FIG. 4), the links that form this element have been appropriately slotted at their respective points of attachment to the pivot pin 1102a.

The locking element 150 includes a laterally protruding pin against which a bidirectionally effective torsion spring 153 will yieldably bear. This biasing spring 153 loosely encircles a boss .154 on the diagonal brace 104 of the carriage frame. The direction of the force that the spring exerts on the element 150 is controlled by the position of a cooperating bar 156 pivotally mounted on the boss 154.

The bar 1516 has two

pins

157 and 158 affixed to its respective ends. The pin 157 is located between the radially extending upper and lower ends of the biasing spring 153, as is the pin 155 of the locking element 150. The other pin 158 overlies a curved surface 2041) of the leg in 204, which surface is indented at its opposite ends. It will be apparent that the arrangement of the bar 156, the element 150, and the interconnecting spring 153 is like that of a toggle. Whenever the bar 5156 is in a generally horizontal position (FIGS. 4 and 6), its pin 157 is below a line drawn through the centers of the pivot pin 102a and the boss 154, and the spring 153 is so stressed that its upper end depresses the pin 1:55 of the element 150 which is then biased clockwise as viewed in the drawings. On the other hand, whenever the bar is in a generally vertical position (FIG. 2), the pin 15-7 is above the same line and the spring is so stressed that its lower end tends to lift the pin 155, whereby the ele ment 150 is biased counterclockwise.

The operation of the reverse-movernent-preventing means of my invention will now be described. Upon movement of the switch member 203 in a clockwise, switch-closing direction from its open position shown in FIG. 2, the pin .157 of the bar 156 goes overcenter, and consequently the biasing spring 153 starts depressing the locking element 150. As the switch member passes a predetermined first position, before the movable arcing :ontact 202 has engaged the relatively stationary arcing :ontact 42, the locking element 150 attains such a tilted disposition on the elongated element 255) that it will prevent return of the switch member to its open position. While clockwise movement of the switch member continues, the curved surface 20% travels under the pin 158 of the bar 156, thereby holding this bar in the position shown in FIG. 6. As a result, the spring 153 yieldably maintains the locking element 15% in its tilted disposition which permits unimpeded clockwise motion of the element 259 relative to the

pins

151, 152. However, any attempted reverse movement of tie switch member will cause the element ZSGand the

pins

151, 152 to bind any thereby to physically lock the switch member before it can move appreciably in the reverse direction.

When the movable switch member passes a predetermined second position, after the arcing contacts 2% and 42 have touched each other and main contact engagement has taken place, a depending portion 259a of the elongated element 251? meets the pin 152 of the locking element 150 and starts lifting the latter element out of its PEG. 6 disposition against the force of the biasing spring 153. Consequently, the .re-verse-rnovement-preventing means becomes disabled on further clockwise movement of the switch member beyond this second position. Shortly before reaching its closed position (FIG. 4), the switch member 203 traverses a predetermined position in which the curved surface 284]) is moved beyond the pin 158 of the bar 156, whereupon the bar 155 pivots to a reset position in readiness for a later reversal in the direction of the locking element bias when the switch is subsequently opened. The reversemovement-preventing means is now rendered ineffective to prevent contact separation.

It will be appreciated from the foregoing description that my non-reversing mechanism is effective during the switch-closing operation to prevent separation of the circuit-making contacts once engaged before the movable switch member 2% reaches the last-mentioned predete-rmined position. Consequently, the switch cannot blow open if initially closed on a severely shortcircuited external electric power circuit, and the high forces of reaction associated with such a closing are not transmitted to the manual operating handle did. Furthermore, the operator cannot begin a successful switch-opening operation until the switch member has been moved all the way to said predetermined position, whereby the assumed minimum switch opening time is assured.

When the switch member 203 is subsequently moved in a counterclockwise, switch-opening direction from its closed position shown in FIG. 4, the pin 157 of the bar 156 goes overcenter again and the biasing spring 156 starts exerting an upwardly directed force on the locking element pin 155. As the switch member passes a predetermined fourth position, before the main contacts of the switch have separated, the locking element 1% assumes such a lifted disposition on the elongated element 250 that it will prevent return of the switch member to the closed position. While counterclockwise movement of the switch member continues, the curved surface 264]; travels under the pin 158 of the bar 156, thereby holding this bar in a nearly vertical position, and as a result the spring 153 yieldably holds the locking element 150 in its lifted disposition which enables the elongated element 25% to slide between the

pins

151 and 152 in the counterclockwise direction without binding. However, the elements 25% and 150 are now effective to prevent any appreciable movement of the switch member in the clockwise direction until this member approaches the aforesaid first position.

In response to the switch member returning to its open position (FIG. 2), the locking element 15f) is tilted against the force of the biasing spring 153 to its original disposition in which the elongated element 250 will again be able, without binding, to slide between the

pins

151 and 152; on clockwise movement of the switch member 12 2%, and the curved surface 20 4b passes beyond the pin 153 of the bar 156 which pivots to a reset position in readiness for another reversal in the direction of the lock ing element bias when the switch is subsequently closed. The irreversible opening operation described above ensures that the switch is fully open before any closing operation can be successfully begun, whereby optimum closing speed and action can be consistently obtained. While a preferred form of my invention has herein been shown and described by way of illustration, many modifications will occur to those skilled in the art. The claims which conclude this specification are therefore intended to cover all such modifications as fall within the true spirit and the scope of the invention.

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

1. A switch comprising:

(a) a relatively stationary electric contact;

(b) a member adapted to support another electric contact, said member being disposed for movement between a predetermined first posi-tion in which said contacts are separated and a predetermined second position in which said contacts are in engagement with each other;

(0) operating means for moving said member; and

(d) mechanical means effective throughout movement of said member from said first position to said second position for preventing any appreciable reverse movement thereof before the member reaches its second position, said reverse-movement-preventing means being independent of said operating means.

2. The switch of claim 1 in which means is provided for disabling the reverse-movement-preventing means on further movement of the supporting member beyond its second position.

3. A switch comprising:

(a) a relatively stationary electric contact;

(b) a member adapted to support another electric contact, said member being disposed for movement between a predetermined first position in which said contacts are separated and a predetermined second position in which said contacts are in engagement with each other;

(c) operating means for moving said member;

((1) means effective on movement of said member from said first position in which the direction of said second position for preventing any appreciable reverse movement there-of before the member reaches its second position; and

(e) means for disabling said reverse-movement-preventing means on further movement of said member beyond its second position;

(f) said reverse-movement-preventing means being additionally effective on reverse movement of said member from its second position toward said first position for preventing any appreciable movement of the member in the direction of its second position until it has approached its first position.

4-. A switch comprising:

(a) a relatively stationary electric contact;

(b) a first member having a fixed disposition relative to said contact;

(c) a second member mounted on said first member for reciprocal motion relative thereto along a predetermined course between predetermined open and closed positions, the second member being adapted to effect engagement between another electric contact and said relatively stationary contact on movement thereof in a given direction along said course from its open position to its closed position and to effect separation of said contacts on reverse movement thereof from closed to open positions;

(d) one of said members having affixed thereto an elongated element whose longitudinal centerline is oriented generally parallel to said course;

(e) a tiltable locking element having spaced-apart transverse portions frictional-1y engaging opposite sides of said elongated element on opposite sides of a plane perpendicular to said centerline, said locking element being pivotally attached to the other member to enable at least one of its transverse portions to move obliquely with respect to said centerline; and

(f) biasing means effective during movement of said second member in said given direction from a predetermined position before contact engagement to a predetermined position after contact engagement for yieldably mantaining said locking element in such a tilted disposition on the elongated element that such movement is accompanied by unimpeded relative motion of the elongated element and the transverse portions of said locking element, while any attempted reverse movement of the second member causes said elements to bind and thereby to prevent reverse movement.

5. The switch of claim 4 in which there is means effec- 6. The switch of claim 4 in which there are additionally provided:

(g) means responsive to movement of the second member from said after-contact-engagement position to said closed position for tilting the locking element on the elongated element against the force of said biasing means to another disposition in which reverse movement of the second member toward said open position will be accompanied by unimpeded relative motion of the elongated element and the transverse portions of said said locking element; and

(b) means for obtaining a reversal in the direction of force exertion on said locking element by said biasing means during reverse movement of the second member from a predetermined position before contact separation to a predetermined position after contact separation, the biasing means yieldably holding said element in said other disposition during such reverse movement.

7. The switch of claim 6 in which they are further provided:

(g) means responsive to movement of the second member from said after-contact-separation position to said open position for tilting the locking element against the force of said biasing means to its original disposition in which movement of the second member toward said closed position will be accompanied by unimpeded relative motion of said elements; and

(h') means for obtaining the original direction of force exertion by said biasing means during movement of the second member in said given direction between said before-contact-engagement and said after-contact-engagement positions, the biasing means yieldably maintaining the locking element in its original disposition during such movement.

8. A switch comprising:

(a) a relatively stationary electric contact;

(b) a reciprocally movable member adapted to support another electric contact, said member being movable in a given direction to carry the supported contact into wiping engagement with the first-mentioned contact and being movable in the reverse direction to separate the supported contact from the first-mentioned contact;

(c) operating means for moving said member in either direction; and

(d) means efiective during movement of said member in said given direction for preventing separation of said contacts once engaged, said last-mentioned means being subsequently rendered ineifective to prevent contact separation when in the course of movement in said given direction said member has reached a predetermined position.

References Cited by the Examiner UNITED STATES PATENTS 2,333,604 11/1943 Wallace 200-97 2,811,604 10/1957 Cole et al. 200116 ROBERT K. SCHAEFER, Primary Examiner. H. HOHAUSER, Assistant Examiner.

Claims

1. A SWITCH COMPRISING: (A) A RELATIVE STATIONARY ELECTRIC CONTACT; (B) A MEMBER ADAPTED TO SUPPORT ANOTHER ELECTRIC CONTACT, SAID MEMBER BEING DISPOSED FOR MOVEMENT BETWEEN A PREDETERMINED FIRST POSITION IN WHICH SAID CONTACTS ARE SEPARATED AND A PREDETERMINED SECOND POSITION IN WHICH SAID CONTACTS ARE IN ENGAGEMENT WITH EACH OTHER; (C) OPERATING MEANS FOR MOVING SAID MEMBER; AND (D) MECHANICAL MEANS EFFECTIVE THROUGHOUT MOVEMENT OF SAID MEMBER FROM SAID FIRST POSITION TO SAID SECOND POSITION FOR PREVENTING ANY APPRECIABLE REVERSE MOVEMENT THEREOF BEFORE THE MEMBER REACHES ITS SECOND POSITION, SAID REVERSE-MOVEMENT-PREVENTING MEANS BEING INDEPENDENT OF SAID OPERATING MEANS.