US3366761A

US3366761A - Loadbreak for open type cutouts

Info

Publication number: US3366761A
Application number: US440186A
Authority: US
Inventors: Jr Sidney R Smith
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1965-03-16
Filing date: 1965-03-16
Publication date: 1968-01-30
Anticipated expiration: 1985-01-30

Description

Jan. 30,L 1968 s. R. SMITH, JR 3,366,761

LOADBREAK FOR OPE'N TYPE cUToUTs Filed Mam 16, 1965 4 sheets-sheet 1 Jan. 30, 196.8 s. R. SMITH, JR- v l 3,366,761

LOADBREAK FOR OPEN TYPE CUTOUTS 4 Sheets-Sheet 2 Filed March 16, 1965 /3 KW7/26g.

Jan. 30, 1968 v s. R. SMITH, JR 3,366,761

' v LOADBREAK FOR OPEN TYPE cUToUTs Filed March 16, 1965 4 Sheets-Sheet I5 Jan. 30, 1968 6 s. R. SMITH, JR 3,366,761

LADBREAK FOR OPEN TYPE CUTOUTS Filed March 1'6, 1965 4 Sheets-Sheet y 4 nited States Pate t 3,366,761 LOADBREAK FOR OPEN TYPE CUIOUTS Sidney R. Smith, Jr., Stockbridge, Mass., assigner to General Electric Company, a corporation of New York Filed Mar. 16, 1965, Ser. No. 440,186 4 Claims. (Cl. 2041-114) This invention relates to loadbreaks for open type cutouts and more particularly to improvements in the construction and operating mechanism thereof.

A cutout as this term is used in the electric -power distribution art is a certain kind of circuit interrupter. Usually it is a renewable fuse device in which case it is called a fuse cutout. When the fuse or fuseholder is in the open air it is called an open type fuse cutout and when the fuse or useholder is in a housing it is called an enclosed type fuse cutout. A fuse, however, is not essential and there is a form of cutout known as a disconnecting cutout which is the functional equivalent of a disconnecting switch, and the structural equivalent of a fuse cutout except that the fuse is replaced by a simple switch blade. Both fuse cutouts and disconnecting cutouts can be used to interrupt or open a circuit which is not carrying load current and fuse cutouts can and, of course, are intended to interrupt overload currents. However, one thing that both fuse cutouts and disconnecting cutouts have in common is that they are not suitable for interruptingy load current like a circuit breaker.

A- loadbreak as the term is used here is a load current interrupter attachment or tool for adapting a cutout to interrupt load current.

In accordance with this invention there is provided a novel and simple enclosed but vented loadbreak device having a simple pivotally mounted arcuate shaped movable contact in a conlined arc chute of arc extinguishing gas evolving material which device is suitable either as an attachment to an open type cutout or as a switch stick mounted tool for use with such cutouts.

An object of4 the invention is to provide a novel and simple loadbreak device for open cutouts.

Another object of the invention is to provide a low cost and lreliable loadbreak device for open cutouts.

A further object of the invention is to provide a new and improved combination of a loadbreak and a cutout for obtaining proper automatic coordinated operation of both devices during both opening and closing with a simple switch stick.

The invention will be better understood from the following description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims.

In the drawings:

FIG. 1 is a perspective view of a preferred embodiment of the invention mounted on an open type cutout,

FIG. 2 is an enlarged partly broken away detailed perspective view of the main contacts and latch assembly of the cutout shown in FIG. l,

FIG. 3 is a side elevation view of the loadbreak device shown in FIG. l,

FIG. 4 is a secional view taken on line 4-4 of FIG. 3,

FIG. 5 is a detailed view of the movable contact carrying drag arm of the loadbreak device shown in FIG. 3,

FIG. 6 is a view similar to FIG. 3 but partly in phantom and with the contacts separated for drawing out and extinguishing an arc inside the device,

FIG. 7 is a side elevation view of the assembly shown in FIG. l but with the latch lever rotated to a position where r it is starting to release the latch holding the main contacts together,

FIG. 8 is a View similar to FIG. 7 after the latch has been released and the main contacts have opened,

FIG. 9 is a view similar to FIG. 8 in which the contacts of the loadbreak are fully opened and the loadbreak device has interrupted the load current,

FIG. 10 is a view similar to FIG. 9 in which the cutout has been fully opened and the loadbreak contacts have :returned to their normally closed position,

FIG. 11 is a view similar to FIG. 10 showing the closing operation of the cutout,

FIGS. l2 and 13 are modifications in which the loadbreak device is mounted on a switch stick instead of on the cutout.

Referring now to the drawings and more particularly to FIG. 1, there is shown therein an open type cutout designated generally by the reference numeral 1 on which is mounted the loadbreak device designated generally by the reference numeral 2. While the invention is not dependent on any particular form of open type cutout, it is particularly suitable for use with open type cutouts of the form constituting the subject matter of my Patent Number 3,238,330 granted March l, 1966 and assigned to the present assignee. As shown, it comprises essentially a Y- shaped main support casting 3 into two of whose arms are fitted two similar straight exible insulating and supporting members 4 which may, for example, comprise a resin impregnated glass be'r core sheathed with elastomeric material such as butyl rubber. On the free end of the upper member 4 there is fitted a so-called latch casting 5 and on the free end of the other member 4 there is tted a so-called hook casting 6. Electrically and mechanically bridged between the castings 5 and 6 is a fuseholder tube 7 the lower end of which is seated in a so-called toggle casting 8 having trunnions 8 seated in the hook casting 6 for providing a pivotal or hinge connection. The upper end of the fuse tube 7 carries a latch and latch release assembly designated generally by the reference numeral 9, the details of which are more clearly shown in FIG. 2 which will be described hereafter. As shown, the loadbreak device 2 is mounted on this latch release assembly.

Referring now to FIG. 2, the latch casting 5 is provided with a line terminal 10 and a pair of guide ears 11 terminating in lateral projections 12. Between the guide ears 11 where they join the main body of the latch casting 5 there is positioned a relatively txed but resiliently mounted main contact 13 backed by a spring 14 of strip material and electrically connected to the casting and line terminal 10 by a high conductivity copper strap 15. Mounted as an integral part of the latch assembly 9 on the upper end of the fuse tube 7 is a movable main contact 16 for engaging the fixed main contact 13. Associated with the main movable contact 16 are lateral projections or shoulders 17 which t into notches 18 in the guide ears 11 for latching the main contacts closed. A latch release lever 19 is pivotally mounted at 20 on the assembly 9 and a spring 21 is provided for biasing it to its fully retracted position as shown in FIGS. 1 Iand 2, i.e., the latch release lever 19 is in its extreme counterclockwise position around the pivot axis 20. Cooperating bumper stops 22 and 23 on the latch casting 5 and the assembly 9 respectively limit the inward movement of the upper end of the fuse tube when the main contacts are slammed shut or closed. The latch release lever 19 terminates in an eye 24 for receiving the hook of a switch stick. The loadbreak 2 is attached to the latch release lever 19 by a bracket 25 so that the main body of the loadbreak 2 is rotatable about the pivotal axis 20 of the latch release lever 19 as well as about the trunnion axis of the lower end of the fu-se tube 7 in the hook casting 6.

The latch mechanism is such that a downward pull on the eye 24 will cause the opposite bifurcated end of the lever 19 to engage the bottom sides of the guide ears 11 thus applying leverage which tends to pry the outer ends 3 of the flexible members 4 apart so that the notches 18 can slip over the projections 17 for releasing the latch and allowing the main contacts 13 and 16 to separate.

Returning now briey to FIG. 1, hook casting 6 has a lower line terminal 26 and is provided with spring contacts 27 for insuring good electrical connection between the casting 6 and the toggle casting 8. The fuse link (not shown) in the fuseholder 7 is typically of the buttonhead type, whose head is seated under a metal cap 27 threaded to the top of the fuseholder tube. Emerging from the lower end of the fuse tube 7 is the pigtail or lead wire 28 from the fuse link which is attached in any suitable manner such as by `a Wing nut 29 (shown in FIG. 7) to the toggle casting 8. The main electric circuit for the device shown in FIGS. 1 and 2 is, therefore, from the terminal 10 through the strap 15 to the main fixed contact 13 thence to the main movable contact 16 through the fuse and pigtail 28 and spring fingers 27 and hook casting 6 to the line terminal 26.

Referring now to FIGS. 3 and 4, the loadbreak device 2 comprises a pair of sector shaped plates 30 of insulating material each having a pair of radial sides 31 and a segment shaped side 32, these plates being `attached along their periphery by bolts or rivets and being slightly dished on the interior so as to form a closed narrow or thin sector shaped arc chute 33. The material of the plates 30 is preferably of the kind which evolves an arc extinguishing gas when an electric arc plays thereon, .a suitable material being methylmethacrylate or fiber. Near the junction of one radial side and the segment shaped side is a conducting bracket 34 attached to the mounting bracket 2S and which carries =a fixed auxiliary arcing contact 35 extending into a corner of the arcing chamber. Cooperating with this auxiliary stationary arcing contact 35 is a movable auxiliary arcing contact of segmental shape designated by the reference numeral 36 which is attached to a drag arm 37 pivotally mounted on the plates 31 near the junction of their radial sides. A suitable coil spring 38 serves to bias the

contacts

35 and 36 closed yand the arm 37 is provided with a conducting hook 39 for engaging one of the lateral projections 12 on one of the guide ears 11 of the latch casting in FIG. 1. The movable contact 36, of course, extends through an opening 4f) in the loadbreak device 2 and its arcing tip is hook shaped .as shown at 41 so that when the drag arm 37 is pivoted and the auxiliary contacts are separated the movable contact 36 cannot pull out of the arcing chamber 33. Near the pivot point or where the arc chute 33 converges to its narrowest extent gas vents 42 are provided for relieving excess pressure and also contributing to the arc extinguishing action of the loadbreak device 2.

The operation of the device as thus far described is as follows. Referring to FIG. 7, the latch release lever 19 has been rotated clockwise about its pivot 20 so as to bring its bifurcated end into contact with the bottom surface of the guide ears 11 of the latch casting 5 which, of course, also has the effect of rotating the loadbreak unit 2 clockwise about the same pivot so that the angular position of these parts has been displaced clockwise about that pivot relative to their positions in FIGS. 1 and 2.

In FIG. 8 the latch has been released in the manner previously described thus permitting still further clockwise rotation of the latch release lever 19 and the loadbreak device 2 about the pivot axis 20 which has the effect of moving the tip of the hook 39 toward the lateral projection 12 so that at about the same time that the main contacts 13 and 16 open the hook 39 contacts the lateral projection 12 thus establishing a conducting path around the main contacts from the projection 12 through the hook 39, the movable auxiliary contact 36, the fixed auxiliary contact 35, the

brackets

34 and 25, and through the latch release lever 19 to the top of the fuse tube.

As the fuse tube 7 pivots clockwise about its trunnions the drag arm 37 stays hooked to the projection 12 and separated as shown in FIG. 9 until, when the loadbreak the auxiliary arcing contacts in the loadbreak device 2 are device 2 is fully opened, a continued downward pull or yank on the eye 24 will cause the flexible arms 4 to give enough to allow the hook 39 to pass under the projection 12 whereupon the loadbreak device 2 will snap closed as shown in FIG. 10. In this manner, all of the arc extinguishing duty required in breaking the load current is carried by the loadbreak device 2 and is not imposed on the main contacts.

If now it is desired to close the circuit, an upward push on the eye 24 by a switch stick hooked therein will return the latch release lever 19 and the loadbreak 2 to their angular positions relative to the fuse tube 7 shown in FIG. 1, i.e., to their fully retracted positions in which the hook 39 will pass under the lateral projection 12 without touching it and with ample clearance so that no arcing will take place between the hook 39 and the projection 12 and the circuit is not closed or reestablished until the main contacts come together so that the circuit is always reestablished through the fuse in case there should be a condition of the circuit which would cause an overload or short circuit current to flow, i.e., the protective properties of the fuse are always available on reclosing of the device.

In the modification shown in FIG. 12, the loadbreak device 2 is `attached by a suitable bnacket `43 to a switch stick 44 and the drag arm 37 is attached to one of the lateral projections 12 by means of a flexible conducting lead 45 provided with a terminal eyelet slipped over projection 12. In this manner, when the switch stick 44 is pulled down and the main contacts separate all of the load current will flow through the loadbreak device 2. However, continued downward movement will cause the loadbreak contacts to separate and thus break the load current because vas this ydownward movement continues the slack in the lead 45 will be taken up. lOnce the arc is extinguished, the hook of t-he switch stick can be taken out of the eye 24 and the lead 45 slipped off the projection 11. Reclosintg can t-hen be effected in the usual manner for the cutout without, of course, connecting the loadbreak device in the circuit during the closing Operation.

FIG. 13 shows another modification in which instead yof using a flexible pigtail the loadbreak 2 is reversed Kand the hook 39 is used 'for engaging the lateral projection 12. In this modification a different bracket 46 attaches t'he loadbreak 2 to the switch stick 44. The operation is otherwise generally similar in that when the switch stick releases the latch and allows the main contacts to open the hook 39 will engage the projection 12 thus ca-using the current to ow through the loadbreak device 2 which then draws out the -arc and interrupts the current. After the device Ihas :been opened, the switch stick can be removed and the loadbreak 2 either removed or pivoted laround its bracket so that it does not come into lplay during a reclosing operation of the cutout.

For high voltage circuits, a number olf the loadbreak devices 2 can be axially aligned and mounted on a com- -mon shaft with the units serially connected so that in general if the voltage rating of each loadbreak device is v and there are n units then by employing enough units almost any voltage V=n v can be interrupted.

Because the arc in the loadbreak `device is made to lengthen itself and stay within the contines of the enclosed arc chute, it can interrupt current with great depend-ability. Control -o-f the arc is maintained because it is not allowed to get out Iof the arc chute.

While there have been shown and described particular embodiments of the invention, it will -be obvious to those skilled in the art that changes and modifications may be imade without departing 'from the invention, and therefore it is intended by the appended claims tto cover all such changes yand modifications as fall within the'true spirit and scope of the invention.

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

1. A loadbreak devi-ce for an open type cutout comprising, -a at thin sector shaped body of arc extinguishing gas evolving insulating material having a hollow interior forming a sector shaped arcing chamber, said sector shapes being similarly oriented and each having two angularly displaced straight radial sides extending from a common center and joined at their other ends by a segment shaped side, an external arm coextensive with a radial side of said body and piv-otally attached thereto at the common center of its radial sides for angular movement about said center in the plane of said body, a spring coiled about said center for biasing said arm toward said body, an opening in the radial side of said body adjacent said anm and adjacent the segment side of said body communicating with the hollow interior of said body, an elongated contact attached to said arm and extending through said opening into said sector shaped arcing chamber, said elongated contact conforming in shape lengthwise to the segment shaped side of said arcing chamber, a xed contact in said arcing chamber near the other end of its segment shaped side tfor cooperating with the end of said elongated contact, a lateral extension on the interior end of :said elongated contact .for preventing its being Withdrawn yfrom said arcing chamber, and vents in said chamber extending through the Walls of said body portion near the common center of its radial sides.

2. The combination, with an open cutout of the type having a conducting arm 4pivotally mounted at one end with a main lmovable contact at the other end for latched closed engagement with a lmain xed contact having a lateral projection, said main movable Contact carrying a pivoted hot-stick-hook-receiving eye latch release member, of a loadbreak device mounted on said pivoted latch release member and 'having a pair of biased closed separable arcin-g contacts one of which is connected by said mounting means to said main movable contact, the other arcng contact having -a projection for engaging the projection on said main xed contact when said latch is released and said contact arm is pivoted to open position.

3. The combination, with yan open type cutout having a pair of spaced terminals one of which has a hinged support and the other of which has a fixed main contact, a conducting member pivotally attached at one end to said hinged support and having at the other end a movable main cont-act for engaging said fixed main contact, a latch for holding said main contacts engaged, a latch release lever pivotally mounted on said conducting member, and ia conductive lateral projection extending from said fixed main contact, of a normally closed loadbreak device mount-ed on said pivOtally mounted latch release member, said device 4having a contact operating pnojection, said projections being so oriented that when said late-h release member is pivoted in a direction to release said latch and `said conducting member is pivoted to open said main contacts said projections er1-gage each other, and when said latch release member is pivoted in the opposite direction and said conducting member is pivoted Ito latch said main contacts closed said projections clear each other.

4. In combination, an open type 'fuse cutout having a iiuse-holder tube pivotally attached at one end toa resilient mounting arm, said tube at the other end having a movable main contact for latched closed engagement with a fixed contact carried by an end olf another resilient mounting arm, a latch release lever pivotally mounted on said fuseholder tube and electrically connected to said movable main contact, said lever being spring biased to a `full retracted normal latch closed position, a lateral conducting projection connected to said fixed main contact an enclosed loadbreak current internupter having a pair of normally closed arcing duty contacts one of which is fixed and the other attached to a movable drag arm having an end projection, a spring for biasing said drag arm to circuit closed position, said loadbreak interruptor being mounted on said latch release lever whereby when said lever is pivoted to release said latch and said fuseholder tube is pivoted to open said main contacts said .projections engage each other for completing a conductive path around said main contacts through said projections and said interruptor in series, further opening movement of said main contacts causing said drag arm to open the internupter contacts until said Iprojections pull clear of each other and said interrupter contacts snap closed, and whereby on closing of said main contacts said lever pivots in the opposite direction to cause said projections to clear each other so that circuit closing is always made ;through the main contacts and the iuse in the fuseholder.

References Cited UNITED STATES PATENTS 2,098,578 11/ 1937 Halmmerly 20D-114 2,351,426 I6/ 1944 Healis 200*l49 2,526,387 10/1950 Milliken 20D-144 X 2,571,864 10/1951 Graybill 200--149 2,986,619 5/1961 McCloud 200-114 3,145,283 8/1964 Date et al 20G-149 3,235,688 2/ 1966 Fink et al 200-114 BERNARD A. GILHEANY, Primary Examiner.

LEWTTTER, Assistant hbcamr'nerY UNITED STATES PATENT oFEICE CERTIFICATE 0F CORRECTION Patent No. 3,366,761 January 30, 1968 Sidney R. Smith, Jr.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column

4, 9 unti1,'when the loadbreak" and insert the same after "Z are" in line Z same column 4 same column 4 line I3 before "2" insert device Signed and sealed this 15th day of July 1969.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Edward M. Fletcher, J r.

Attestng Officer Iine l, strike out "separated as shown in FIG.

Claims

2. THE COMBINATION, WITH AN OPEN CUTOUT OF THE TYPE HAVING A CONDUCTING ARM PIVOTALLY MOUNTED AT ONE END WITH A MAIN MOVABLE CONTACT AT THE OTHER END FOR LATCHED CLOSED ENGAGEMENT WITH A MAIN FIXED CONTACT HAVING A LATERAL PROJECTION, SAID MAIN MOVABLE CONTACT CARRYING A PIVOTED HOT-STICK-HOOK-RECEIVING EYE LATCH RELEASE MEMBER, OF A LOADBREAK DEVICE MOUNTED ON SAID PIVOTED LATCH RELEASE MEMBER AND HAVING A PAIR OF BIASED CLOSED SEPARABLE ARCING CONTACTS ONE OF WHICH IS CONNECTED THE SAID MOUNTING MEANS TO SAID MAIN MOVABLE CONTACT, THE OTHER ARCING CONTACT HAVING A PROJECTION FOR ENGAGING THE PROJECTION ON SAID MAIN FIXED CONTACT WHEN SAID LATCH IS RELEASED AND SAID CONTACT ARM IS PIVOTED TO OPEN POSITION.