US3290459A

US3290459A - Fusible electric switch having means for pivotally supporting replaceable cartridge fuses on a tiltable carriage

Info

Publication number: US3290459A
Application number: US420267A
Authority: US
Inventors: Howard D Kurt
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1964-12-22
Filing date: 1964-12-22
Publication date: 1966-12-06
Anticipated expiration: 1983-12-06

Description

Dec. 6, 1966 H. D. KURT 3,290,459

FUSIBLE ELECTRIC SWITCH HAVING MEANS FOR PIVOTALLY SUPPORTING REPLACEABLE CARTRIDGE FUSES ON A TILTABLE CARRIAGE Filed Dec. 22, 1964 5 SheetsSheet 1 FIG./.

//v VENTOR. Ho WARD D. KURT,

ATTORNEY H. D. KURT Dec. 6, 1966 FUSIBLE ELECTRIC SWITCH HAVING MEANS FOR PIVOTALLY SUPPORTING REPLACEABLE CARTRIDGE FUSES ON A TILTABLE CARRIAGE 5 Sheets-Sheet 2 Filed Dec. 22, 1964 INVENTOR. HOWARD 0. KURT,

B W ATTORNEY Dec; 6, 1966 H D. KURT 3,290,459

FUSIBLE ELECTRIC SWI'I CH HAVING MEANS FOR PIVOTALLY Filed Dec. 22, 1964 SUPPORTING REPLAGEABLE CARTRIDGE FUSES ON A TILTABLE CARRIAGE 5 Sheets-Sheet 5 /NVENTOR.' HOWARD D. KURT,

ATTORNEY Dec. 6, 1966 H. D. KURT 3,290,459

FUSIBLE ELECTRIC SWITCH HAVING MEANS FOR PIVOTALLY SUPPORTING REPLACEABLE CARTRIDGE FUSES ON A TILTABLE CARRIAGE Filed Dec. 22, 1964 5 Sheets-Sheet 4 /NVEN70/?.' Ho WARD 0. KURT,

A TTOR/VEY 3,290,459 ALLY H. D. KURT Dec. 6, 1966 FUSIBLE ELECTRIC SWITCH HAVING MEANS FOR PIVOT SUPPORTING REPLACEABLE CARTRIDGE FUSES ON A TILTABLE CARRIAGE 5 Sheets-Sheet 5 Filed Dec. 22, 1964 /NVE/VTO/? HOWARD Z2 KURT, 5y QQJIMt S. mm ATTORNEY United States Patent Filed Dec. 22, 1964, Ser. No. 420,267 8 Claims. (Cl. 200-50) This invention relates to electric switches, and more particularly it relates to a switch in which contact means for switching an electric current circuit and fuse means for protecting the circuit are integrally combined.

The present invention has special utility in relatively high current (e.g. 1200 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 high as 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 fault condition will preexist in the protected circuit when a service entrance switch is being closed. On realizing this, an operator is likely to react by immediately attempting to reopen the switch. If the fault current magnitude is sufliciently high, the fuses will interrupt it with dispatch before the operator can separate the main contacts of the switch. But for complete protection, the separable contacts of a service entrance switch should be designed to safely interrupt the maximum amount of current (e.g. 6 times rated full-load current, or 7,200 amperes) that the fuses will let through, without blowing, for the minimum length of time required to carry out a switch opening operation.

Heretofore it has been conventional practice in commercially available service entrance switches to mount the fuses in a relatively stationary position adjacent to the movable switch contacts, whereby in each pole of the switch the two electrical junctions formed at the respective fuse terminals are in series with the two electrical junctions interposed by the switch contacts. High-current switches of such design generally have had one or more of at leastthe following shortcomings: (l) Relatively large and bulky physical dimensions; (2) undesirable heat generation and cumulative power losses at the four separate, serially-connected electrical junctions; (3) relatively inconvenient arrangement of main contacts and operating mechanism for installation and servicing purposes; (4) dif ficult access to blown fuses for the purpose of removing and replacing the same; (5) lack of assurance that both terminals of a blown fuse are deenergized prior to removing the fuse.

'In some prior art fusible switch designs, provisions have been made for mounting a cartridge fuse in place of the movable blade of a switch. Such designs generally have not been suitable for multipole high-current switches. For service entrance applications in particular, they are subject to some of the shortcomings enumerated above and, where switching and fuse-access functions have been combined in a single operation, still other shortcomings are potentially involved: (1) High forces required to close 3,290,459 Patented Dec. 6, 1966 the switch; (2) hazard on opening the switch to an operator standing nearby; (3) relatively large space occupied by the switch when open.

Accordingly, a general object of the present invention is the provision of an improved switch for high-current service entrance applications and the like.

A more specific object of my invention is to provide means for facilitating maintenance of a compact, multipole, fusible electric circuit disconnecting device that is designed to avoid or to minimize the above-mentioned shortcomings of the prior art.

Another object is to provide a relatively simple yet very safe and reliable switch of this kind in which a blown fuse is movable, after first opening the switch contacts, to a special position where both of its terminals are disconnected and the fuse is exposed for convenient removal and replacement.

My invention contributes materially to the construction of a 3-pole, high-current fusible switch that is characterized, to an unusual degree, by compactness in size, safety and convenience in operation and maintenance, and low cost in manufacture.

In carrying out my invention in one form, a compact, dead-front, high-current fusible switch is provided with a manual operating handle and a mechanism for safely closing or opening the switch without exertion of untoward force by the operator. The mechanism is connected to a movable switch member the back side of which is adapted to support one or more removable cartridge fuses. The switch member is pivotally mounted on a carriage that is pivotally mounted in turn on a stationary part of the switch. Hence the carriage is disposed for reciprocal movement between predetermined operating and tilted positions. Operation of the mechanism while the carriage is in its operating position causes each fuse to be moved into or out of a closed circuit position in which it bridges an associated pair of spaced-apart relatively stationary contacts by directly engaging the same.

Whenever the switch is open, the carriage can be moved to its tilted position where a blown fuse will be exposed, in a completely deenergized state which is clearly visible to the operator, for safe and convenient removal and replacement. Since both terminals of the fuse are thus disconnected from the associated stationary contacts, either one of these contacts can be safely connected to the electric power source. In one aspect of the invention interlocking means is provided to ensure that the carriage is anchored in its operating position except when the switch is open. In still another aspect of the invention, the carriage is made separable from the stationary part of the switch in its tilted position, thereby enhancing the ease with which the switch can be initially installed and the convenience of subsequently servicing its fuses, contacts, and operating mechanism.

. 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 an enlarged side view of the movable bridgelike switch element shown in FIG. 2 and of the means by which it is removably supported;

FIG. 5 is a side elevation similar to FIG. 2 but with the bridge-like switch element shown in its closed circuit position; and

FIG. 6 is a side elevation of the switch shown in FIG. 1 with the front frame and associated switch elements tilted in accordance with my invention to a disconnected position.

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 110 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 constnuction of the stationary unit 11 of the switch will now be described. The 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. 6, 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 afiixed, and this plate is additionally fastened to the midsection of the post 12 by means of adiagonal 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 101.

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 18]) 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 inswlating 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 sideby-side relation to each other on the insulating

channels

20 and 21 of the frame described above. A front view of 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 bladellike contact inserted in the gap therebetween. The

contacts

32 and 33 preferably comprise defiectable silver plated copper bars having their flat sides in parallel vertical planes that are perpendicular to the channels 21 and 22 and having their forward edges 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 each of the lower contacts 41. The shaft 60 is insulated so that the separate contacts 41 will remain electrically isolated from each other, and it is surrounded at each of these contacts by a pair of

annular members

62 and 63.

.The annular member 63 is housed in the dished member 37, and preferably it comprises a non rotatable nut having an internal screw thread. The other member 62 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 60 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. 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

34 and 37 to the attached conductor 30, with each member 34 being rigidly fastened (by the means shown at 39 in FIG. 2) to the upper insulating channel 20 instead of to 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 201 having blade-like main contacts 201a and 2011) at opposite ends thereof is provided. The element 201, 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 20111 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, lowresistance connections between these cooperating main contacts is then obtained by actuating the above-described clamping means.

The common drive shaft 60 of the clamping means associated with the respective upper contacts 31 and the corresponding drive shaft 60 below have been intercon nected for joint rotation by a pair of tie bars 64. 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 101, 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 of 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. 5), 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. 5), 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 arc 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 side structures of this frame comprises an angle forming a vertical front corner post 102, a side plate 103 affixed to the post 102 near its lower end and extending rearwardly therefrom, and a diagonal brace 104 interconnecting the rear of plate 103 and the upper end of post 102. A shaft 105 extends horizontally across the bottom of the carriage and is journalled 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, in

accordance with my invention, 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 5. This position is determined 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 lon as the carriage 101 is in the operating position, the upper lip 14a of each notch 16 overhangs 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 degrees to a second or tilted position shown in FIG. 6, which position is determined by an appendage 102a 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 103 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. In accordance with my in vention, 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

jawlike 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 201b of the respective fuses 201. The preferred construction of these fuse terminal holders is best seen in FIG. 4.

Each of the lower fuse terminal holders 206 is in the form of a generally rectangular collar 206a projecting rearwardly from the bottom of the switch member 203, to which it is afiixed, and a relatively thin 'U-shaped bracket 2061) subtending the collar. The blade-like fuse terminal 20117 is loosely embraced by the collar 20611, which restricts lateral movement of the blade, and it is supported by the interior surfaces of the bracket 2061) which limit edgewise movement thereof. The bracket 206b is made thinner than the blade 201b so as to avoid interfering with the direct electrical connection between the blade and the jaw-like contact 41. The hook-like protrusion 2060 shown at the bottom of the holder 206 will extend behind one of the tubular bolts 62 on the lower rotatable drive shaft 60 of the contact clamping means whenever the portable carriage 101 is in its aforesaid operating position.

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. A threaded bolt 208 attached to the free end of each of the arms 205a is normally secured in a cooperating nut 209 affixed to the switch member 203, thereby releasably fastening the contact 202 to the switch member. The arms 205a loosely embrace the blade-like fuse terminal 201a and hence restrict lateral movement of the blade. The side 202b 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 jawlike contact 31.

By unfastening the arms 205a from the switch member 203, the upper fuse terminal holder 205 can be pivoted about 202a from a normal position (shown in solid lines in FIG. 4) to another position (shown in broken lines) 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 mechanism in its preferred form includes the manual operating handle 120. As can be seen in FIGS. 1 and 2, handle 120 depends radially from the front end of a short horizontal shaft 121 to which it is affixed. The shaft 121 extends through the escutcheon 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 plate-like crank 123 is keyed to the rear end of the shaft 121. V

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 123 is 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 126 projecting radially from a central portion of the shaft 105 to which it is rigidly anchored, whereby a universal joint 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 sideof 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 shownin 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 the escutcheon 110. Whenever the handle is in its vertical (open) position, which position is defined by a first shoulder 123b of the plate 123 engaging a boss 106a 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 113 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 (closed) position, which position is defined by an opposing shoulder 123d of the plate 123 engaging the same boss 106a, the first shoulder 123:5 will move just beyond the plunger 112 which is then 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 12812. 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 through about one-half of its -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 slot 128 moves rearwardly and cams 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. 5. This 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 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. 5, 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 10c mounted on the adjacent supporting 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 1812 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 105 and its cam members 127 to turn clockwise from the position shown in FIG. 5. If desired, spring means (not shown) could be coupled to the handle 120 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. position, a camming surface 129 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. 5, the slot 262 will register with a pin 66b 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 pivot pin 119.) The crank 66 is also provided with a slot 660 diametrically opposite the pin 66b, which slot registers with the protruding axle of the roller 260. Thus the crank 66 is coupled so 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. 2, 3, and 5 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 201a (or 2011)). This contact clamping action is more fully explained above in connection with 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 5) where it is retained by the releasable locking means 112, 113 previously described. Brief considera tion will now be given to a switch opening operation,

10 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. 5) of the shaft 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 pulls 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 12812 in the member 127 approaches the roller 204a, the coupling lever 261 returns to its normal position shown in FIG. 5 and each drive shaft 60 isreturned to its initial angular position, whereby the bolted-pressure connections between

stationary contacts

31, 41 and fuse terminals 201a, 20112 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 204a 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 reaches a vertical position (FIG. 2) where it is again retained by the releasable locking means 112, 113.

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 aifixed to the switch member 203 and a tiltable locking element pivotally attached to the front corner post 102 of the frame of the carriage 101. As is apparent in FIGS. 2 and 5, the elongated element 250 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. The locking element 150 has a pair of spaced-apart

transverse pins

151 and 152 in frictional engagement with opposite sides of the element 250. A bidirectionally effective torsion spring 153 encircles a boss 154 on the diagonal brace 104 of the carriage frame and yieldably bears against a pin 155 protruding laterally from the element 150, the direction of this bias being controlled by the position of a cooperating bar 156 pivotally mounted on the boss 154.

While the switch member 203 is being moved in its clockwise, switch-closing direction between a predetermined first position before the movable arcing contact 202 has engaged the relatively stationary arcing contact 42 and a predetermined second position after main contact engagement takes place, the bar 156 is held by a curved surface 20411 of the leg 204 in a nearly horizontal position (see FIG. 5) that results in the spring 153 depressing the locking element 150 and maintaining it in such a tilted disposition on the elongated element 250 that clockwise movement of the switch member is accompanied by unimpeded relative motion of the element 250 and the

pins

151, 152, whereas any attempted reverse movement of the switch member causes the element 250 and the

pins

151, 152 to bind and thereby to physically lock the switch member before it can move appreciably in the reverse direction. This non-reversing mechanism is thus effective during a switch-closing operation to prevent separation of the cooperating

contacts

202 and 42 once engaged before the movable switch member 203 reaches the aforesaid second position. Consequently the switch cannot blow open if initially closed on a severely short-circuited external electric power circuit, and the high forces of reaction associated with such a closing are not transmitted to the manual operating handle 120.

As the switch member 203 moves into its closed position (FIG. a depending portion 250a of the elongated element 250 lifts the locking element 150 out of its tilted disposition to another disposition that will enable the elongated element to slide between the

pins

151 and 152 without binding on reverse movement thereof. During subsequent counterclockwise movement of the switch member 203 toward its open position, the bar 156 is pivoted clockwise and is held by the leg surface 204a in a nearly vertical position that results in the spring 153 maintaining the locking element 150- in its lifted disposition, whereby the

elements

250 and 150 are 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 150 is tilted against the force of the bias spring 153 to its original disposition in which the elongated element 250 is again able, without binding, to slide between the

pins

151 and 152 on clockwise movement of the switch member 203.

As the movable switch member 203 is returning to its open position near the end of the switch-opening operation, the lobe 12711 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 operating position shown in FIG. 2 to the tilted position mentioned hereinbefore.

In FIG. 6 the portable unit of the opened switch is shown after having been moved, relative to the stationary unit 11, to its tilted position. Such movement is elfected simply by pulling manually the carrying handle 108 of the carriage 101 until the carriage is propelled by its own weight counterclockwise about the axis of its support pins 116. It will be apparent that during this swinging movement of the carriage 101 the axle of roller 260 and the slot 262 at opposite ends of each coupling lever 261 separate, respectively, from the diametrically opposed slot 66c and pin 66b of the associated crank 66. The tilted position of the carriage 101 is reached when the appendage 102a on each of the front corner posts 102 of the carriage frame engages the under side of the cooperating stop pin 15a on each diagonal brace 15 of the stationary unit 11.

In accordance with my invention, the support pins 116 are so located that the above-described movement of the carriage 101 carries the lower fuse terminals 2011) out of engagement with the stationary contacts 41, whereby each cartridge fuse 201 is completely separated from the associated

stationary contacts

31 and 41 of the switch. In the tilted position of the carriage 101, as is best seen in FIG. 6, each fuse has both of its terminals disconnected and deenergized, and it is exposed for safe and convenient removal from the

fuse terminal holders

205 and 206. An operator can easily replace a blown fuse without danger of touching an energized (live) stationary contact of the switch. To improve accessibility and 'hence to expedite the unfastening and disengagement of the upper fuse terminal holder 205, the fuse-supporting switch member can first be moved, relative to the carriage 101, in a clockwise direction on the pivot pins119 to its closed position by turning the manual operating handle 120 through its closing stroke. In order to ensure that the portable carriage 101 cannot then be moved from its tilted position to its operating position (FIG. 5), each cam member 127 has been provided wi'h a boss 127k that will not pass a laterally-displaced edge 15b of the stationary diagonal brace 15 until the cam member 127 is returned to its original angular position by completing the opening stroke of the handle 120.

While a preferred form of my invention has now 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 scope of the invention.

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

1. A switch comprising:

(a) a first unit including means for removably supporting a bridge-like electroconductive element and additional means for movably mounting the supporting means on the first unit;

(b) a second unit having a relatively stationary pair of spaced-apart electric contacts;

(0) means for pivotally mounting said first unit on said second unit for reciprocal movement relative to the second unit to and away from a first position in which said element is adapted directly to engage and hence electrically to interconnect both of said contacts;

((1) anchoring means for locking said first unit in its first position to said second unit;

(e) means for so moving said supporting means relative to said first unit while in said first position that said element disengages at least one of said contacts; and

(f) means responsive to said movement of said supporting means for disabling said anchoring means, thereby releasing said first unit for angular movement relative to the second unit to a second position in which said element is completely separated from both of said contacts and is exposed for safe and convenient removal from said supporting means.

2. The switch of claim 1 in which said bridge-like electroconductive element comprises a cartridge fuse.

3. In combination:

(a) a portable unit including means for removably supporting a cartridge fuse, the supporting means being mounted on the portable unit for angular movement relative thereto between predetermined closed and open positions;

(b) a relatively stationary unit having a pair of spacedapart electric contacts;

(c) means separably hinging said portable unit to said stationary unit for angular movement between predetermined first and second positions, the supported fuse directly engaging and hence electrically interconnecting both of said contacts when the portable unit is in said first position and said supporting means is in said closed position, and the supported fuse being completely separated from both contacts and being exposed for safe and convenient removal from the supporting means whenever the portable unit is in said second position; and

( d) means for preventing movement of the portable unit from its first to its second positions whenever the supporting means is in said closed position.

4. The combination of claim 3 in which means is provided for preventing movement of the portable unit from second to first positions when the fuse supporting means is in its closed position.

5. In combination:

(a) a carriage having a front side and a back side and means adapted removably to support a cartridge fuse on the carriage adjacent to the back side thereof, said supporting means being movably mounted on said carriage;

(b) a relatively stationary frame and a pair of spacedapart electric contacts mounted on the frame,

() means for hinging said carriage to said frame for angular movement relative to the frame between a first position in which the fuse is adapted to engage and 'hence to interconnect both of said contacts and a second position in which the fuse is disposed for safe and convenient removal from said supporting means;

(d) switching means operative from the front side of said carriage for so moving said supporting means while the carriage is in said first position that the fuse disengages at least one of said contacts; and

(e) interlocking means on the frame for preventing movement of said carriage away from its first position so long as the fuse is engaging both of said contacts and for permitting such movement of the carriage after an operation of said switching means.

6. The combination of claim in which the supporting means is pivotally mounted on the carriage for angular movement relative thereto about a first axis located in the vicinity of the back side thereof, and in which the carriage is hinged to the frame for swinging between its first and second positions about a second axis parallel to said first axis and located in the vicinity of the front side of the carriage.

7. In combination:

(a) a portable carriage having a front side and a back side and means adapted removably to support a cartridge fuse adjacent to the back side of the carriage, said supporting means being mounted on said carriage for angular movement relative thereto:

(b) a relatively stationary frame and a pair of spacedapart electric contacts mounted on the frame;

(c) means for pivotally mounting said carriage on said frame so that the carriage is angularly movable to and away from a predetermined position, said mounting means including anchoring means for releasably locking the carriage in said predetermined position to the frame;

5 (d) a mechanism connected to said supporting means and operative from the front side of said carriage while in said predetermined position to move the supporting means so as to carry the supported fuse alternatively into engagement with both of said contacts and out of engagement with at least one of said contacts; and

(e) means effective when the supported fuse has been carried out of engagement with at least one of said contacts for disabling said anchoring means, thereby releasing said carriage for angular motion from said predetermined position to a diiferent position in which the fuse is completely separated from both of said contacts and is exposed for safe and convenient removal from said supportnig means.

8. The combination of claim 7 in which the supporting means is adapted removably to support three separate cartridge fuses and in which three separate pairs of spaced-apart electric contacts are mounted on the frame for engagement respectively by said fuses upon operation of the mechanism.

References Cited by the Examiner UNITED STATES PATENTS 2,504,876 4/1950 Pringle 20050 2,982,827 5/1961 Goetz 200-50 3,213,221 10/1965 McMillen et a1 200-50 References Cited by the Applicant UNITED STATES PATENTS 1,519,044 12/1924 Paiste.

ROBERT K. SCHAEFER, Primary Examiner. .T. R. SCOTT, Assistant Examiner.

Claims

1. A SWITCH COMPRISING: (A) A FIRST UNIT INCLUDING MEANS FOR REMOVABLY SUPPORTING A BRIDGE-LIKE ELECTOCONDUCTIVE ELEMENT AND ADDITIONAL MEANS FOR MOVABLY MOUNTING THE SUPPORTING MEANS ON THE FIRST UNIT; (B) A SECOND UNIT HAVING A RELATIVELY STATIONARY PAIR OF SPACED-APART ELECTRIC CONTACTS; (C) MEANS FOR PIVOTALLY MOUNTING SAID FIRST UNIT ON SAID SECOND UNIT FOR RECIPROCAL MOVEMENT RELATIVE TO THE SECOND UNIT TO AND AWAY FROM A FIRST POSITON IN WHICH SAID ELEMENT IS ADAPTED DIRECTLY TO ENGAGE AND HENCE ELECTRICALLY TO INTERCONNECT BOTH OF SAID CONTACTS; (D) ANCHORING MEANS FOR LOCKING SAID FIRST UNIT IN ITS FIRST POSITION TO SAID SECOND UNIT; (E) MEANS FOR SO MOVING SAID SUPPORTING MEANS RELATIVE TO SAID FIRST UNIT WHILE IN SAID FIRST POSITION THAT SAID ELEMENT DISENGAGES AT LEAST ONE OF SAID CONTACTS; AND (F) MEANS RESPONSIVE TO SAID MOVEMENT OF SAID SUPPORTING MEANS FOR DISABLING SAID ANCHORING MEANS, THEREBY RELEASING SAID FIRST UNIT FOR ANGULAR MOVEMENT RELATIVE TO THE SECOND UNIT TO A SECOND POSITION IN WHICH SAID ELEMENT IS COMPLETELY SEPARATED FROM BOTH OF SAID CONTACTS AND IS EXPOSED FOR SAFE AND CONVENIENT REMOVAL FROM SAID SUPPORTING MEANS.