US2403121A - Circuit interrupter - Google Patents

Description

' y 2, 1946- H. RAWLINS ET AL 2,

CIRCUIT INTERRUPTER July 2, 194 H. L. RAWLINS ETAL C IRCUI T INTERRUPTER 4 Sheets-Sheet 3 Filed Jan. 29, 1942 lNVENTOR5 f/erberf Paw/I anafhn f M/Kos WW ATTORNE Patented July 2, 1946 OIRGUITINTEBBUPTER Herbert L. Bawlins, Pittsburgh, and John I.

Mikos, Wilkinsburg, Pa aasignors to Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Application January 29, 1942, SerlalNo. 428,110 so cum. (01. 200-411) This invention relates generally ,to circuit interrupters, and more specifically to high voltage fuses.

One object of this invention is to provide a novel type of high voltage fuse which is relatively simple in construction and economical of manufacture, while being capable of efliciently interrupting relatively large currents.

Power fuses have been used wherein a fusible element is connected between terminals with one of the terminals spring-biased to draw out the are formed when the fuse blows. One way by which current has been conducted to the movable terminal is'by the use of a flexible shunt. such a shunt takes up considerable space. and must be moved by the spring during circuit interruption.

Another object of this invention therefore is to provide a novel fuse construction for conducting current to a movable fuse terminal without the use of flexible shunts or the like.

Another object of this invention is to provide a normally enclosed fuse of novel construction having an operating member which is projected through the fuse enclosure when the fuse blows.

Another object of this invention is to provide for cooperation with a novel fuse construction of I the type described, novel releasable means for holding the fuse in circuit and adapted to be released by an operating member actuated upon blowing of the fuse.

Another object of this invention is to provide novel latching means for a fuse of the type described for normally releasably maintaining the fuse in circuit but operable in response to blowme of the fuse to release the fuse for movement out of the circuit, while at the same time permitting manual manipulation of the fuse into and out of the circuit.

Another object of this invention is to provide novel releasable latch means for a fuse, which latch means upon release thereof is operable to move the fuse associated therewith out of the circuit.

Another object of this invention is to provide a novel drop-out fuse mounting having a novel movable mounting element capable of releasably holding the fuse in an intermediate open position, and of cushioning the opening movemen thereof.

These and other objects of this invention will become more apparent upon consideration of the following detailed description of preferred embodiments thereof when taken in connection with the attached drawings, in which:

. 2 Fi re 1 is a front elevational view of a fuse constructed in accordance with this invention;

Fig. 2 is a side elevational view of the fuse shown in Fig. 1, with the upper and lower contacts shown in section;

Fig. 3 is a longitudinal sectional view through the fuse cartridge shown in Figs. 1 and 2;

Fig. 4 is a section View of the upper contact construction taken substantially on the line IV-IV of Fig. 2;

Fig. 5 is a section view of the upper fuse contact construction similar to the section of this contact shown in Fig. 2, but with the fuse removed;

Fig. 6 is a view similar to Fig. 5, but with the parts shown in a different position, and with the upper end of the fuse shown in elevation;

Fig. '7 is an enlarged, partial, central sectional view of a fuse showing "a modified form of fuse construction;

Fig. 8 is aview similar to Fig. '1 showing another modified construction;

Fig. 9 is a view like Figs. '7 and 8 but showing still another modification;

Fig. 10 is a transverse section view taken substantially on the line X-X of Fig. 9; and.

Fig. 11 is a view like Figs. 7, 8 and 9, but illustrating still another modified form of fuse construction.

Referring first to the construction of the fuse per se as illustrated in Figs. 3, 9, and 10 of the drawings, it will be observed that there is provided a fuse tube 2 of insulating material, such as fiber, synthetic resin or the like, and opposite ends of the fuse tube are adapted to be closed by end terminal caps 4, 6, respectively. The lower portion of fuse tube 2, as viewed in Fig. 3, is provided with a plurality of blocks 8, of an insulating material which is capable of evolving an arc extinguishing gas when in proximity to an electric arc, supported within the tube. The insulating material '8 is preferably boric acid, but any other insulating material having the property set forth above may be employed, such, for example, as fiber or a synthetic resin. The insulating blocks 8 are each provided with a central bore-l0, so that the bores, when the blocks are mounted in the tube, form an elongated arc passage of restricted cross-section. The lower end of the arc passage formed by bores I0 is flared outwardly as shown at H, and the lower block ll which acts to support the blocks 8 on end cap 6, is preferably of fiber, a synthetic resin or other gasevolving material which has a greater strength than boric acid. An arcing'contact rod i6 is adapted to be normally positioned within the arc passage formed by bores l0, and the lower end of this rod is electrically connected to terminal cap 6 by a fusible strip ll, paralleled by a strain member 20, secured in any desired manner to the rod l6 and terminal cap 6. As shown, fusible strip 18 and strain member 20 have one end inserted in a slot in the lower end of arcing contact rod It to be secured therein in any desired manner, such as by soldering or riveting, and the other end of the fuse strip and strain means is bolted or otherwise secured as at 24 to an inwardly bent tongue 22 formed integral with end terminal cap I. Fusible strip It may be of any desired fusible material, such, for example, as silver, zinc, tin, or alloys thereof. The strain member 20 paralleling the fusible strip is preferably of a higher resistance material which has a greater tensile strength than the material comprising fusible strip It.

An insulating spacer block 28, having a central aperture, is preferably mounted within fuse tube 2 immediately above insulating blocks I for supporting a conducting washer 28. A tube ll of good electrical conducting material such, for example, as copper or the like, extends between conducting washer 28 and a. washer 32 also of a good electrical conducting material which is clamped between end terminal cap 4 and the upp r end of fuse tube 2. As shown in Fig. 3. the end terminal caps 4 and 6 may be secured in position in any desired manner but are preferably secured on the ends of fuse tube 2 by a pressing operation forming indentations in the end cap flanges entering into the material of tube 2. Washer 32 is provided with a central aperture and with integral inwardly extending supporting and locking tongues l4, for a purpose to be hereinafter referred to. Just above insulating spacer 20, arcing contact rod II is provided with an enlarged portion 38 having a tapered lower surface 38, on which is seated an and coil of a coiled tension spring 40, the opposite end coil of which is supported by tongues 84, so that the rod It is biased upwardly towards end terminal cap 4, and strain member 2| is normally maintained under tension. Spring 4| also maintains washer I2 in pressure engagement with conducting tube SI, and this in turn forces the tube against washer 2! to provide good electrical contact at these points.

In order to provide a good electrical connection from arcing contact rod It to terminal cap 4, flexible strips 42 of a conducting material such as copper, are preferably secured to conducting washer 28 at the lower end of conducting tube 30, and the free ends of the strips are inserted between the tapering contact surface ll on the arcing contact rod and the lower coil of spring n. Thus. spring 40 also acts to maintain contact strips 42 in engagement with tapered surface ii on the contact rod under pressure. Flexible contact strips are preferably secured to or formed integral with a contact ring 44, to facilitate assembly of the parts. It will be noted that arcing contact rod II is provided with an integral extension 4| above enlarged portion 30, andthattheendterminalcapsland. areeach provided with a central aperture normally closed by displaceable closure disks 48 and Il, respectively, which may be reieasably maintained in position, such, for example, as by cementing or the like.

The electric circuit through the fuse described above extends "from one end terminal cap 4 4 through conducting washer 32, conducting tube 30, contact strips 42, contact arcing rod 16, fusible strip I8 to the other end terminal cap 8. When an overload appears on the circuit in whichthe fuse is connected, fusible strip I8 will melt and strain member 20 will be vaporized shortly thereafter, to thereby release arcing contact rod II and permit spring 40 to move it upwardly towards terminal cap 4. As soon as fusible strip II and strain member 20 are melted, the pressure created in the flared passage l2, augmented by gas evolved from the material of bores III, as arcing rod is moves upwardly, will be sufficient to displace closure disk 50 to thereby permit the gases 15.

,wardly and extension 46 of the rod wil1 engage closure disk 4! and displace the disk so that the extension will be projected from terminal cap 4 an amount limited only by engagement of enlarged portion 36 of the rod with tongues 34 on washer 32. It will be noted that the space between tongues 34 is slightly less than the diameter of rod extension 45, so that in passing upwardly between the tongues the extension will bend them upwardly, and the tongues will therefore lock extension 46 in its projecting position and prevent any subsequent tendency of the rod or extension 46 to move into the fuse' tube. During interruption, when an arc is drawn between the lower end of arcing contact rod l8 and arcing tongue 22 on end cap 6, contact strips 42 will move out from between the lower turn of spring 40 and the tapered surface 38 on the contact rod, so that as the rod moves upwardly, the current will be carried by spring 40. Inasmuch as the arcing time is very short, it has been found that the spring will be undamaged by the passage of current therethrough for such short periods of time. Accordingly, in this fuse construction no flexible shunt is necessary to carry current from end terminal cap 4 to the moving arcing contact rod it, because current is normally carried to the rod by conducting tube 30 and separable contact strips 42, whereas during the short arcing period, coil spring 40 is permitted to carry the current. Coil spring 4| also performs the function of moving contact rod it an amount sufficient to proiect extension 45 thereof out through the aperture in terminal cap 4 where it is locked-against movement by locking tongues 34.

A modified type of separable connection between arcing contact rod l6 and the inner end of tubular conductor 30 is illustrated in Fig. 7, wherein a plurality of connections may be provided between these elements in the normal position thereof, and wherein each connection comprises a strip 52 of flexible conducting material connected to conducting washer 2B or the lower end of tube ill or to both, and a second strip 52 connected to arcing contact rod ii in any desired manner, such, for example, as by soldering or the like. The adjacent ends of the two conducting strips 52 of each connection are then brought together in face to face relation, as shown in Fig. 7, and secured at 54 by rupturable means, for example, as by soldering or the like.

In the operation of this embodiment of the invention, when a circuit interrupting operation occurs, arcing contact rod i8 is moved upwardly by spring 40, and the conducting strips 52 of each connection between the contact rod and tube lll are straightened out and pulled apart at the soldered connection 54. The strips 52 are 7 readily pulled apart by the spring, because the act of straightening out the strips will bend the securing means 54 substantially 80. This bending action will at least weaken securing means to such an extent that but a small force is needed to pull the strips apart.

In the embodiment of the invention shown in Fig. 8, a plurality of connections each of which may comprise a pair of rigid conducting members 88 and 58 and a flexible conducting member 82 are provided between arcing contact rod I8 and conducting tube 88. As shown in Fig. 8, one of the rigid conducting strips 88 preferably is secured at one end to tube 88, for example, as by soldering or the like, whereas the other rigid conducting strip 58 is secured to one end of flexible strip 82 in any desired manner, such as by riveting or the like, and the other end of strip 82 is secured to contact rod I8 in any del. Extending outwardly beyond end terminal cap I, fixture I8 is provided with ,integral latch e aging extensions 88 on each side of terminal cap I, for a purpose to be referred to. A hook eye portion 88 is also formed integral with the flxture and depends from channel section 88 thereof to be located in front of the fuse as shown in Fig. 2, to permit manipulation of the sired manner, such, for example, as by soldering,

riveting or the like. The other ends of rigid conducting strips 56 and 58 are then secured together in abutting relation by soldering or the like 88. This places the solder connection 88 between two cantilever members 56 and 58 so that when the fusible and strain elements of the fuse melt and contact rod I8 is moved upwardly by spring 88, flexible conducting strips 62 will be straightened out and pull the end of strip 58 to which they are secured upwardly, and cause strips 58 to pivot about solder connection 88 to thereby readily break this soldered connection, and thereby interrupt the circuit from conducting tube 88 to arcing contact rod I8, so that the current during arcing will be carried by spring 88.

Still another type of separable connection between conducting tube 88 and arcing contact rod I8 is illustrated in Fig. 11, wherein a substantially U-shaped member 84 of a rigid conducting material has the free end of one leg thereof secured to the under surface of enlarged portion 36 of the contact rod, as by solder 88, and the other leg thereof is secured to one end of a substantially Z-shaped strip 88 of flexible conducting material, for example, as by a rivet 18. The other end of flexible conducting strip 88 is connected to an integral tongue 14 formed on conducting tube 88, for example, as by a rivet I2.

When circuit interruption occurs, it will be observed that since only one leg of rigid U-shaped member 84, shown in Fig. 11, is secured to enlargement 86 of the contact rod, that as soon as the contact rod is moved upwardly as by spring 40, flexible strip 88 will be straightened out and cause rotation of U-shaped member 84 about its soldered connection 86 to thereby readily break this connection and interrupt the circuit from tube 88 to the moving contact rod. An advantage of the solder type of connections shown in Fig. 11, as well as in Figs. 7 and 8, is that they normally form a solid path of good electrical conducting material for current flowing through the fuse, while at the same time they are capable of being readily separated or broken to permit interruption of the circuit within the arcing passage formed by bores I0.

Referring now to Fig. 2, it will be observed that for the purpose of mounting on circuit contacts, the fuse described above is adapted to have bandling and mounting fixtures applied to the terminal caps thereof. Thus, terminal cap 4 is provided with a clamping ring 18 generally circular ,in form but provided on one side with a noncircular extension I1, and over this extension is provided a hook eye and latch fixture 18 having a supporting portion substantially channelfuse about its lower pivotal mounting.

Lower end terminal cap 8 of the fuse is also provided with a clampin ring 88 similar to clamping ring I1 for the upper end of the fuse, and a hook eye contact fixture 88 of semi-circular shape and of channel form in cross-section is adapted to be mounted over extension 88 of the clamping ring and be secured in firm engagement with terminal cap 6 by a screw 8| passing through the web of fixture 88, to be threadedly engaged with extension 83 of the clamping ring. The fixture 88 is provided with an integral upwardly extending projection 82, having a hook eye 88 formed therein generally circular in form except at the side adjacent fixture 88, wherein a flaring slot portion 86 is located. Extension 82 on contact fixture is also provided intermediate hook eye 84 and the channel section thereof with laterally extending guide arms 88 at opposite sides thereof for a purpose hereinafter referred to. Adjacent each end of U-shaped flxture 88, there is provided an outwardly laterally extending trunnion 88 for pivotally supporting the fuse.

The fuse is adapted to be supported upon a pair of vertically spaced insulating supports, such, for example, as the insulators I88 and I02. The lower insulator I82 is provided with a generally U-shaped contact secured thereto as, for example, by machine screws I85 extending through the base portion I84 of the contact. The legs I88 of the pivot contact are formed adjacent their outer ends with upwardly flaring notches I88 terminating at the inner lower ends thereof in a. keyhole notch portion II 8, with a laterally extending guide edge I I2 provided at one end of one side of the notch I 88 in each leg. Each leg is also provided with an integral, downwardly extending terminal leg portion I I4 for connection of a line conductor thereto. Intermediate legs I86 of the pivot contact, a leaf spring member I IS of a resilient conducting material, together with backing leaf spring members I and I28 are preferably secured to the base I of the contact, for example, as by one of the contact mounting screws I85. The leaf spring IIG, as shown in Fig. 1, is provided in the upper portion thereof with a pair of spaced longitudinally extending slits to form independently movable outer leg portions I I8, and a central leg portion I2II. Preferably the central leg portion I20 of spring H6 is secured by screw I85, and the outer leg portions II8 are preferably preset laterally outwardly of the plane of leaf spring III and central leg I28 thereof, and have the upper ends thereof extended beyond inner leg I28 and bent to form detent portions I22.

Referring to Fig. 2, it will be observed that when the fuse is mounted so that trunnions 88 are received in the keyhole portions III of slots I88 in the legs of the contact, withdrawal of trunnions 88 is prevented by engagement of guide arms 88 beneath guide edges III of notches Ill.

It will also be observed that in this tion of the parts detent portions I22 of conducting spring I I3 are in engagement with the upper inner edge of contact fixture 80, and preferably in this position of the parts, the outer legs I I8 of spring contact strip 8 have been stressed so that a good contact pressure is insured between the detent portions I22 thereof and the adjacent edge of contact flxture 80 on the fuse tube. Upon pivotal movement of the fuse in a clockwise direction about trunnions 88, it wil1 be observed that guide arms 88 will first be moved clear of guides edges I I2 on the pivot contact arms I08, but at this time trunnions 88 will have their widest dimension presented to the opening in keyhole slot IIO, so that in order to remove the fuse from the pivot contact it is necessary to further rotate the fuse in a clockwise position to 9. depending position, substantially 180 from that shown in Fig. 2. It will be observed that at a position 45 from that shown in Fig. 2, detent portions I22 at the upper ends of arms II8 of leaf contact spring II8, will enter detent notches I21 on contact fixture 80, so that if desired the fuse may be retained in this position. However, this detent action does not offer very great resistance to continued clockwise movement of the fuse, so that the fuse may be moved manually past this position to a depending position, wherein hook eye 84 will then be presented in front, of the fuse and the fuse may then readily be removed from the supporting hinge contact by lifting upwardly on hook eye 34. It should also be noted that the lower end of contact spring II3 forms a resilient bumper for the fuse when it reaches a position substantlally 180 from that shown in Fig. 2, so that in automatic drop-out operation, or in any case where the fuse moves to its depending position under the influence of gravity, it will impinge upon the lower end of contact spring H3 and thereby'prevent damage to insulator I02, or the fuse, or parts thereof.

The upper supporting insulator I03 has secured thereto a generally rectangular shaped contact supporting and enclosing hood which includes a top wall I28, a rear end wall I30, opposite side walls I32 flared outwardly adjacent the free corners thereof as at I33, and a partial front end wall I34 joined to top wall [23. Rear end wall I is substantially circular in form, as shown in Fig. 1, and has opposed notches I33 formed in portions thereof beyond side walls I32 for receiving mounting screws I38, for securing rear wall I38 of the hood to supporting insulator I30. The top wall I23 of the contact hood is provided with an integral upwardly extending terminal lug I43 for the connection of a line conductor thereto. Interiorly of the contact housing there is provided a supporting pin I42, extending transversely of and mounted in side walls I32, for supporting a floating contact and latch member I44 for movement within the housing. The floating contact and latch member I44 may be in the form of a casting, and, as shown, is substantially rectangular in form, including opposite side members I43 secured together by an integral front connecting member I48, a rear top connecting member I53, and a rear bottom connecting member I52. The side legs I43 of the floating contact are provided with integral extensions having elongated slots I54 therein for receivingsupporting pin I42, so that the contact may move ina plurality of different directions within the housing. A coil compression spring I33 engages between a supporting lug 8 I58 on the top wall I28 of the housing and a similar supporting lug I80 formed integral with transverse connecting member I50 of the floating contact to bias the floating contact I44 in a counterclockwise direction relative to pin I42. A rounded projection I5I is provided at the base of lugs I58 and I30 at each side thereof to permit angular movement of spring I58 without distortion thereof. The floating contact I44 is electrically connected with top wall I28 of the housing by a flexible shunt I32, secured to the top wall of the housing and to cross member I48 of the contact, for example, as by machine screws I84. The lower edges of side legs I48 of the floating contact, are provided intermediate their ends with notches I88 adapted to receive latch engaging projections 84 on the fuse. A releasable supporting lever I88 is pivotally mounted between side legs I48 of the floating contact by means of a pivot pin I38, and this lever is biased for movement in a clockwise direction relative to floating contact I44 into engagement with cross member I52 of the contact, by a coil compression spring I12 engaging between lever I33 and cross member I50 of the contact. The forward end of lever I88 is provided with a flattened portion I10 positioned, when a fuse is engaged in notches I88, so as to be directly over the top of the fuse. A supporting lug I14 is also formed integral with lever I88 for cooperation with an integral supportinglug I13 formed on the rear wall of the contact housing. Stop lugs I18 are also formed integral with rear wall I30 of the contact housing, for engagement with cross member I50 of the floating contact to limit movement thereof towards the top wall I28 of the housing.

The. operation of the contact and latching structure described above will be best understood by referring first to Fig. 5 of the drawings, which illustrates the position of the parts with the fuse removed. Under such conditions it will be noted that supporting lug I14 of lever I88 is in engagement with supporting lug I18 on the rear wall of the contact hood, so that spring I58 has caused the floating contact to move in a generally clockwise direction about lugs I14 and I18, until supporting pin I42 has reached the upper end of slot I54. In this position it will be observed that the lower edges of the side legs I48 of the floating 7 contact have their outer ends inclined upwardly, so that when a fuse is moved pivotally in a counterclockwise direction into engagement with the floating contact, it may cause counterclockwise pivoting of the contact about lugs I14, I18, by engagement of latching lugs 84 on the fuse with the lower edges of legs I48 of the floating contact while stressing coil spring I58, until the latch lugs are received in notches I88 formed in legs I48 of the floating contact. At this time the parts will have assumed the positions shown in Fig. 2, and it will be noted that spring I58 has been stressed to the extent that supporting pin I42 is now intermediate the ends of slot I54 on the floating contact. This will provide a good contact pressure between the lugs I48 of the floating contact and fixture 18 associated with upper fuse terminal 4.

Now, with'the fuse in the closed circuit posi-- tion shown in Fig. 2, in the event an overload appears on the circuit causing the melting of fusible strip I3 and strain member 20 of the fuse, so that the arcing contact rod I8 is moved upwardly as previously described, when extension 9 45 on rod I8 is projected through the top of the fuse, it will engage the outer end of releasable supporting lever I68, and cause movement of this member in a counterclockwise direction about its pivot I69 to thereby move lug I14 oil! fixed supporting lug I16 so that the inner end of the floating contact is no longer supported, thereby permitting spring I56 to move the contact in a counterclockwise direction about supporting pin I42. counterclockwise movement of floating contact I 44 about supporting pin I42 will cause movement of the upper end of the fuse outwardly, relative to insulator I00, and in a clockwise direction about trunnions 99, to the position shown in Fig. 6 of the drawings. When the parts have attained this position, and even before, it will be obvious that the fuse will have reached an unstable position so that the action of gravity will cause the fuse to drop downwardly to a depending position into engagement with bumper I I as previously described. In this drop-out movement of fuse tube 2, it will not be halted by detent I22 engaging notch I 21 of the fuse, because this notch is purposely made shallow and of such shape that the spring arm detent I22 will be unable to stop the downward movement of the fuse, so that the fuse will move down into engagement with the bumper formed by contact spring H6. The fuse may then be removed from the supporting hinge contact in the manner previously described and replaced by a new fuse, and this fuse may be then rotated in a counterclockwise direction about its trunnions 99 towards closed circuit position. The floating contact I44 will be in the .position shown in Fig. 6 of the drawings, so that, upon continued counterclockwise rotation of the fuse, it will engage cross member I52 of the floating contact to move the floating contact inwardly and in a generally clockwise direction about its supporting pin I42, until lug I14 of lever I68 engages lug IIB on the housing, and passes over the lug by compression of biasing spring I12, to become seated on top of the ing in the position shown in Fig. 2 of the drawings, whereby latch projections 84 on the fuse may enter notches I65 in the lower edges of sides I46 pf gth kfloating contact when the parts will be in the position shown in Fig. 2. i

From the foregoing, it is apparent that the invention disclosed herein provides a novel form of drop-out fuse wherein a normally solid or otherwise good electrical conducting circuit through the fuse is interrupted uponblowing of the fuse by separation of a .portion of this circuit, and the arc extinguished by elongating the same within a restricted arc passage having walls of a gas evolving material, with the arc drawing contact having a portion which is projected outwardly of the fuse only when the arcing terminal is substantially at the end of its path of movement. This is an important feature because by delayingprojection of extension 46 of arcing contact rod I6 from the tube until the arc has been drawn out' substantially the entire length of the restricted arc passage, it is thereby insured that the arc has been subjected to substantially the entire arc extinguishing capacities of the fuse prior to release of the fuse from its line contacts, to thereby ensure that the circuit will always be interrupted within the fuse and no are drawn at the line contacts. The spring which acts to draw out and extinguish the arc within the tube also acts to project the extension 46 through the end of the tube to release a combined floating contact and latch member engaging the upper end of the 10 fuse, and permit the fuse to be moved out of engagement with at least one line contact.

Furthermore, the extension 48 of the arcing rod is not only projected through the central opening in terminal cap 4 by spring 40, but it is positively held in such latch releasing position by engagement of locking tongues 34 therewith, to positivelyensure that the latch releasing means is held in a released position, and thereby make certain that the fuse is released from at least one line contact. 7

The particular contact and latch construction for the upper end of the fuse is especially designed for cooperation with a fuse of the type 'wherein an extension on the arc drawing rod is projected through the fuse to positively engage and actuate a means for positively moving the fuse in a direction out of engagement with one of its line contacts. The floating contact I44 employed is especially efilcient and reliable in operation, while being relatively simple in construction in that but a single spring I58 is utilized for both furnishing adequate contact pressure with the upper fuse terminal, and also initially moving the fuse in a direction away from the contact upon blowing of the fuse. The floating contact and latch are entirely foolproof in construction in that they may be reset solely by moving a fuse into engagement therewith, so that all that is necessary to insert a new fuse in a circuit is merely to rotate it into engagement with the floating contact.

There has also been disclosed herein novel pivot supporting contact structure wherein a single spring is provided for (1) forming a good electrical contact with the lower fuse terminal, (2) forming a detent to maintain the fuse at an intermediate open position when adjusted man-. ually to such position, but ineffective to hold the fuse at such intermediate position upon automatic drop-out operation thereof, and (3) forming a bumper for the fuse when it falls to open circuit position under the influence of gravity.

Having described preferred embodiments of this invention in accordance with the patent statutes, it should be understood that the invention is not to be limited to the particular embodiments disclosed herein, inasmuch as it will be obvious, paricularly to persons skilled in the art, that many changes and modifications may be made in these particular structures without departing from the broad spirit and scope of the invention. Accordingly, this invention should be interpreted as broadly as possible and limited only as required by the prior art.

We claim as our invention:

1. In a circuit interrupter having a pair of terminals, arcing contacts at least one of which is movable away from the other to draw an are, said contacts connected with said terminals, respectively, biasing means for moving said movable contact away from the other of said contacts, electroresponsive means for maintaining said contacts against separation but operative to release said contacts in response to predetermined electrical conditions, and the connection of said movable contact and its corresponding terminal including a solid connection which is capable of being ruptured by said biasing means when said contacts are released.

2. In a circuit interrupter having a pair of terminals, arcing contacts at least one of which is movable away from the other to draw an arc, said contacts connected with said terminals, respectively, biasing means for moving said movable contact away from the other of said contacts, electroresponsive means for maintaining said contacts I against separation but operative to release said contacts in response to predetermined electrical conditions, and the connection of said movable contact and its corresponding terminal including a solid connection having a soldered portion which is capable of being ruptured by said biasing me when said contacts are released.

3. In a circuit interrupter having a pair of terminals, arcing contacts at least one of which is movable away from the other to draw an arc, said contacts connected with said terminals, respectively, biasing means for moving said movable contact away from the other of said contacts, electroresponsive means for maintaining said contacts against separation but operative to release said contacts in response to predetermined electrical conditions, and the connection of said movable contact and its corresponding terminal including a solid connection having a relatively weak portion positioned so as to be subjected to bending stress and to be broken by said biasing means when said contacts are released.

4. In a circuit interrupter having a pair of terminals, arcing contacts at least one of which is movable away from the other to draw an arc, said contacts connected with said terminals, respectively, biasing means for moving said movable contact away from the other of said contacts, electroresponsive means for maintaining said contacts against separation but operative to release said contacts in response to predetermined electrical conditions, and the connection of said movable contact and its corresponding terminal including a solid connection having a relatively weak portion, and a cantilever member connected thereto so that said portion will be subjected to bending stress and broken by said biasing means when said contacts are released.

6. In a circuit interrupterhavi g a p r of terminals, arcing contacts at least one of which is movable away from the other to draw an are, said contacts connected with said terminals, respectively, biasing means for moving said movable contact away from the other of said contacts, electroresponsive means for maintaining said contacts against separation but operative to release said contacts in response to predetermined electrical conditions, and the connection of said movable contact and its corresponding terminal including a solid connection having a relatively rigid part connected at points thereof spaced laterally of the direction of movement of said movable contact. to said movable contact-and its corresponding terminal, respectively, and one of said .connections comprising a solder connection,

whereby said part will be rotated about said solder connection upon separatin movement of said movable contact, to rupture the same.

6. In a circuit interrupter, a tubular enclosure of insulating materialhaving terminals adjacent opposite ends thereof, conducting means in said tube connecting said terminals including means capable of automatically interrupting the circuit in response to predetermined electrical conditions, a movable arcing contact normally held against movement by said interrupting means, means of material capable of evolving an arc extin uish- 1118 as when in proximity to an electric arc forming a restricted arc passage in which said contact is movable, biasing means for moving said contact through said passage in response to fusion of said fusible means, and said contact having a part movable therewith which is pro- 12 jected from one end of said casing only upon movement of said contact by said biasing means to a position adjacent the end of said passage.

'1. In a circuit interrupter, s tubular enclosure of insulating material having terminals adjacent opposite ends thereof, conducting means in said enclosure connecting said terminals including arcing terminals at least one of which is movable in said tube, means capable of automatically interrupting the circuit in response to predetermined electrical conditions for normally preventing movement of said movable arcing terminal, biasing means for moving said movable arcing terminal to a position wherein an end portion thereof projects from one end of said tube upon a circuit interrupting operation by said interrupting means, and the connection between said movable arcing terminal and its respective tube terminal being separable upon movement of said movable arcing terminal from its normal position.

8. In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends thereof, arcing terminals at least one of which is movably mounted in said tube, fusible means connecting said arcing terminals and normally preventing movement of said movable arcing terminal, means biasing said movable arcing terminal for movement upon fusion of said fusible means to a position wherein a portion thereof projects from one end of said tube a predetermined amount, connections between said arcing terminals and said tube terminals, respectively, and the connection between said movable arcing terminal and its respective tube terminalbeing separable upon movement of said movable arcing terminal from its normal position.

9. In a fuse, a fuse tube of insulating mateterial having terminals adjacent opposite ends thereof, arcing terminals at least one of which is rod-like in character and is movably mounted in said tube, fusible means connecting said arcing terminals and normally preventing movement of said movable arcing terminal, means biasing said movable arcing terminal for movement upon fusion of said fusible means to a position wherein one end portion thereofprojects from one end of said tube a predetermined amount, connections between said arcing terminals and said tube terminals, respectively, shoulder means at said one end of said tube, and cooperating shoulder means on said rod-like terminal to limit outward movement thereof to a position wherein said one end portion thereof projects from said tube said predetermined amoimt.

10. In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends thereof, arcing terminals at least one of which is rod-like in character and is movably mounted in said tube, fusible means connecting said arcing terminals and normally preventing movement of said movable arcing terminal, means biasing said movable arcing terminal for movement upon fusion of said fusible means to a position wherein one end portion thereof projects from one end of said tube a predetermined amount, connections between said arcing terminals and said tube terminals, respectively, shoulder means at said one end of said tube, cooperating shoulder means on said rod-like terminal to limit outward movement thereof to a position wherein said one end portion thereof projects from said tube said predetermined amount, and means also at said one end of said tube for automatically holding said rod-like terminal in the position wherein said end portion thereof projects from said tube.

aware:

11. In a fuse. a fuse tube of insulating material having terminals adjacent opposite ends thereof,

arcing terminals at least one of which is rodlike in character and is movably mounted in said tube, fusible means connecting said arcing terminals and normally preventing movement of said movable arcing terminal, means biasing said movable arcing. vterminal for movement upon fusion of said fusible means to a position wherein one end portion thereof projects from one end of said tube a predetermined amount, connections between said arcing terminals and said tube terminals, respectively, shoulder means at 'said one end of said tube, an enlargement on said rodlike terminal positioned to engage said shoulder means to limit outward movement of said terminal to a position wherein said one end portion thereof projects from said tube said predetermined amount, and the connection between said; rod-like arcing terminal and its respective tube terminal including a separable connection with said enlargement,-

12. In a fuse, a replaceable fuse lmit which is adapted to be replaced each time the fuse blows comprising, in combination, a fuse tube of insulating material having terminals adjacent opposite ends thereof, arcing terminals at least one of which is movably mounted in said tube, fusible means connecting said arcing terminals and normally preventing movement of said movable arcing terminal, the other of said arcing terminals being adjacent and electrically connected to one of said tube terminals, said movable arcing terminal being normally spaced from the other of said tube terminals, spring means tensioned between said movable arcing terminal and said other tube terminal, conducting means extending from said other tube terminal and having a connection with said movable arcing terminal which is separable upon movement of said terminal by said spring means, said spring means and separable connection constituting the sole conducting paths between said other tube terminal and thereof, conducting means in said tube connectmovable arcingcontact, whereby said spring means carries the current to said movable arcing contact during arcing.

13. In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends thereof, a line contact, means mounting said tube for movement of one of its terminals into and out of engagement with said line contact, latch means for releasably maintaining said tube terminal in engagement with said line contact, conducting means in said tube connecting said terminals including fusible means and a, movable arcing contact, and biasing means for moving said arcing contact to a position wherein a portion thereof projects from one end of said tube upon fusion of said fusible means, to release said latch means and permit movement of said tube to disengage said tube terminal from said line contact.

14. In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends thereof, conducting means in said tube connecting said terminals including fusible means and a movable arcing contact, biasing means for moving said arcing contact to a position wherein a portion thereof projects from one end of said tube upon fusion of said fusible means, a line contact, means pivotally mounting said tube for movement of one terminal thereof into and out of engagement with said line contact, releasable latch means for latching said tube terminal in engagement with said line contact, and said latch means having a latch releasing part positioned in the path of movement of said portion of said movable arcing contact to release said tube terminal for movement out of engagement with said line contact upon movement of said movable con-tact portion to saidprojecting position. 1

1 15. In a fuse, a fuse tube of insulating material having terminals adiacent opposite ends thereof, conducting means in said tube connecting said terminals including fusible means and a movable arcing contact, means of a material capable of evolving an arc extinguishing gas when in proximity to an electric are forming a restricted arc passage in which said contact is movable, biasing means for moving said contact through said passage in response to fusion of said fusiblemeans, said contact having a part-movable therewithwhich is projected from one end of said casing upon movement of said contact by said biasing means to a position adjacent the end of said passage, a line contact, means pivotally mounting said tube for movement of one terminal thereof into and out of engagement with saidline contact, releasable latch means for latching said tube terminal in engagement with said line contact, and said latch means having a latch releasing part positioned in the path of movement of said portion of said movable arcing contacts to release said tube terminal for movement out of engagement with said line contact upon movement of said movable contact portion to said projecting position and after the arc has been drawn out substantially the entire length of said are passage.

16. In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends ing said terminals including fusible means and a movable arcing contact, biasing means for moving said arcing contact to a position wherein a; portion thereof projects from one end of said tube upon fusion of said fusible means, a line contact, means pivotally mounting said tube for movement of one terminal thereof into and out of engagement with said line contact, said line contact being mounted formovement in a direction towards said one tube terminal and also in a direction to cause movement of said one tube terminal away from said line contact, means resiliently biasing said line contact for movement in said two directions, releasable latch means normally restraining movement of said line contact in said second direction and including a part positioned in the path of movement of said portion of said movable arcing contact to release said line contact for movement in said second direction to move said one tube terminal out of engagement with/said line con-tact upon movement of said movable arcing contact portion to said projecting position.

1'1.r In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends thereof, conducting means in said tube connecting said terminals including fusible means and a movable arcing contact, biasing means for moving said arcing contact to a position wherein a portion thereof projects from one end of said tube moving said arcing contact to a position wherein a a portion thereof projects from one end of said tube upon fusion of said fusible means, a line contact, means pivotally mounting said tube for movement from a substantially upright position wherein one terminal thereof is in engagement with said line contact to a depending position wherein said one terminal thereof is out of engagement with said line contact, releasable latch means for latching said tube terminal in engagement with said line contact, said latch means having a latch releasing part positioned in the path of movement of said portion of said movable arcing contacts to release said tube terminal for movement out of engagement with said line contact upon movement of said movable conmeans for releasably maintaining said tube in a position intermediate said upright and depend- 7 ing positions.

19. In a fuse, a fuse tube of insulating mate rial having terminals adjacent opposite ends thereof, conducting means in said tube connecting said terminals including fusible means and a movable arcing contact, biasing means for moving said arcing contact to a position wherein a portion thereof projects from one end of said tube upon fusion of said fusible means, a line contact. means pivotally mounting said tube for movement. from a substantially upright position wherein one terminal thereof is in engagement with said line contact to a depending position wherein said one terminal thereof is out of engagement with said line contact, releasable latch means for latching said tube terminal in engagement with said line contact, said latch means having a latch releasing part podtioned in the path of movement of said portion of said movable arcing contact to release said tube terminal for movement out of engagement with said line contact upon movement of said movable contact portion to said projecting position, means for releasably maintaining said tube in a position intermediate said upright and depending positions, and resilient stop means for limiting movement of said tube at said depending position.

20. In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends thereof, conducting means in said tube connecting said terminals including fusible means and a movaway from said line contact,,means resiliently biasing said line contact for movement in said two directions. releasable latch means normally restraining movement of said line contact in said second direction and including a part positimied in the path of movement of said portion of said movable arcing contact to release said line contact for movement in said second direction to move said one tube terminal out of engagement with said line contact upon movement of said movable arcing contact portion to said projecting position.

21. In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends thereof, conducting means in said tube connecting said terminals including fusible means and a movable arcing contact, biasing means for moving said arcing contact to a position wherein a portion thereof projects from one end of said tube upon fusion of said fusible means, a line contact, means pivotally mounting said tube for movement of one terminal thereof into and out of engagement with said line contact, said line contact being slidably mounted for movement in a direction towards said one tube terminal and pivotally mounted for movement in a direction to cause movement of said one tube terminal away from said line contact, means resiliently biasing said line contact for movement in said two directions, releasable latch means normally restraining movement of said line contact in said second direction and including a part positioned in the path of movement of said portion of said movable arcing contact to release said line contact for movement in said second direction and move said one tube terminal out of engagement with said line contact upon movement of said movable arcing contact portion to said projecting position, and said line contact having a part engageable by said fuse upon manual movement thereof towards said line contact to pivotaily move said line contact in anopposite direction to reset said latch means. A

22. In a drop-out fuse, an elongated fuse holder having fusible means therein connected between spaced terminals on said holder, an electric circuit in which said fuse is adapted to be connected, means pivotally mounting said holder so that said holder is movable into and out of said circuit, means for releasably maintaining said fuse in closed circuit position including a latch member engageable with said holder and mounted for limited movement in a first direc-- tion toward a latch engaging part of said holder, and in a second direction to move said holder to open circuit position, means resiliently biasing said latch member in said two directions, latch means normally preventing movement of said latch member in said second direction, and means responsive to fusion of said fusible means for releasing said latch means to permit said biasing means to move said latch member in said second direction and said holder to open circuit position.

23. In a drop-out fuse, an elongated fuse holder having fusible means therein connected between spaced terminals on said holder, an electric circuit in which said fuse is adapted to be connected, means pivotally mounting said holder so that said holder is movable into and out of said circuit, means for releasably maintaining said fuse in closed circuit position including a floating latch member engageable with said holder, means biasing said member at a point offset from its point of engagement with said holder in a direction to cause engagement with said 17 holder and movement of said holder to an open circuit position, releasable means for supporting said latch member at a third spaced point to normally prevent movement thereof in a direction to movesaid holder to an open circuit position, and means responsive to fusion of said fusible means for releasing said releasable supporting means.

24. In a drop-out fuse, an elongated fuse holder having fusible means therein connected between spaced terminals on said holder, an electric circuit in which said fuse is adapted to be connected, means pivotally mounting said holder so that said holder is movable into and out of said circuit, means for releasably maintaining said fuse in closed circuit position including a floating latch member engageable with said holder, means biasing said member at a point offset from its point of engagement with said holder in a direction to cause engagement with said holder'and movement of said holder to an open circuit position, releasable means for supporting said latch member'at a third spaced point to normally prevent movement thereof in a direction to move said holder to an open circuit position, means responsive to fusion of said fusible means for releasing said releasable supporting means, and means slidably and pivotally supporting said member to limit the aforesaid movements thereof and retain said member in a position to be engaged by said holder on movement thereof to closed circuit position.

25. In a drop-out fuse, an elongated fuse holder having fusible means therein connected between spaced terminals on said holder, an electric circuit in which said fuse is adapted to be connected, means pivotally mounting said holder so that said holder is movable into and out of said circuit, means for releasably maintaining said fuse in closed circuit position including a circuit contact and latch member engageable with one terminal of said holder and mounted for limited movement in a first direction toward said one terminal and in a second direction to move said holder to open circuit position, means resiliently biasing said latch member for movement in said two directions, latch means normally preventing movement of said latch member in said second direction, and means responsive to fusion of said fusible means for releasing said latch means to permit said biasing means to move said latch member in said second direction and said holder to open circuit position.

26. In a drop-out fuse, an elongated fuse holder having fusible means therein connected be-.

tween spaced terminals on said holder, an electric circuit in which said fuse is adapted to be connected, means pivotally mounting said holder so that said holder is movable into and out of said circuit, means for releasably maintaining said fuse in closed circuit position including a floating latch member engageable with said holder, means biasing said member at a point offset from its point of engagement with said holder in a direction to cause engagement with said holder and movement of said holder to an open circuit position, releasable means for supporting said latch member at a third spaced point to normally prevent movement thereof in a direction to move said holder to an open circuit position, means responsive to fusion of said fusible means for releasing said releasable supporting means, and means supporting said member for limited movement in the aforesaid directions and adapted to retain said member in a position to be engaged 18 by said holder on movement thereof to closed circuit position.

27. In a drop-out fuse, an elongated fuse holder having fusible means therein connected between spaced terminals on said holder, a line terminal, means pivotally mounting said holder for movement of one terminal thereof toward and away from said line terminal, a floating contact member on said line terminal, means electrically connecting said contact and line terminal, means biasing said contact with a force having a component in a direction to move said contact member into engagement with said one holder terminal, and a second component. to move said contact member in another direction to cause movement of said holder away from said line terminal, releasable abutment means normally opposing movement of said contact member under the influence of said second force component, and means operative in response to fusion of said fusible means for releasing said abutment means.

28. In a drop-out fuse, an elongated fuse holder having fusible means therein connected between spaced terminals on said holder, a line terminal, means pivotally mounting said holder for movement of one terminal thereof toward and away from said line terminal, a floating contact member on said line terminal, means electrically connecting said contact and line terminal, means biasing said contact with a force having a component in a direction to move saidv contact into engagement with said one holder terminal, and a second component to move said contact member in another direction to cause movement of said holder away from said line terminal, cooperating abutments on said contact and line terminal one of which is releasable for normally opposing movement of said contact member under the influence of said second force component, and

means operative in response to fusion of saidv fusible means for releasing said releasable abutment.

v 29. In a drop-out fuse, an elongated fuse holder having fusible means therein connected between spaced terminals on said holder, a line terminal, means pivotally mounting said holder for movement of one terminal thereof toward and away from said line terminal, a floating contact member on said line terminal, means electrically connecting said contact and line terminal, means biasing said contact with a force having a component in a direction to move said contact member into engagement with said one holder terminal, and a second component to move said contact member in another direction to cause movement of said holder away from said line terminal, releasable abutment means normally opposing movement of said contact member under the influence of said second force component, means operative in response to fusion of said fusible means for releasing said abutment, means movably supporting said contact on said line terminal when said abutment is released in a position to be engaged by said one holder terminal upon movement thereof toward said line terminal, and means responsive to movement of said contact by said holder for resetting said releasable abutment.

30. In a drop-out fuse, an elongated fuse holder having fusible means therein connected between spaced terminals on said holder, a line terminal, means pivotally mounting said holder for movement of one terminal thereof toward and away from said line terminal, a floating contact member on said line terminal, means electrically connecting said contact and line terminal, means biasin said contact with a force having a component in a direction to move said contact member into engagement with said one holder terminal, and a second component to move said contact member in another direction to cause movement of said holder away from said line terminal, releasable abutment means normally opposing movement of said contact member under the influence 01' said second force component, means operative in response to fusion of said fusible means for releasing said abutment, and means for limiting movement of said contact under the in fluence of said first force component to maintain said contact in a position to be engaged by said holder terminal upon movement thereof toward said line terminal.

31. In a drop-out fuse, an elongated fuse holder having fusible means therein connected between spaced terminals on said holder, a line terminal, means pivotally mounting said holder for movement of one terminal thereof toward and away from said line terminal, a floating contact member on said line terminal, means electrically connecting said contact and line terminal, means biasing said contact with a force having a component in a direction to move said contact member into engagement with said one holder terminal, and a second component to move said contact member in another direction to cause movement of said holder away from said line terminal, releasable abutment means normally opposing movement of said contact member under the influence of said second force component, means operativ in response to fusion of said fusible means for releasing said abutment, means for limiting movement of said contact under the influence of said first force component to maintain said contact in a position to be engaged by said holder terminal upon movement thereof toward said line terminal, means movably supporting said contact on said line terminal when said abutment is released in a position to be engaged by said one holder terminal upon movement thereof toward said line terminal, and means responsive to movement of said contact by said holder for resetting said releasable abutment.

32. In a drop-out fuse having a fuse holder with terminals adjacent opposite ends thereof and fusible means therein connected between said terminals, vertically spaced line contacts, means pivotally mounting said holder adjacent one end thereof near the lower of said line contacts for movement of at least the terminal at the other end thereof into and out of engagement with the upper one of said line contacts, latch means for releasably maintainin said holder in closed circuit position, means responsive to fusion of said fusible means for releasing said latch means to cause said holder to rotate to 5, depending open circuit position, a leaf spring member supported intermediate its ends on said pivotal supporting means and including a detent portion at one end thereof engageable with cooperating detent means on said holder to releasably maintain said holder at an intermediate position, and the other end of said spring member positioned to be resiliently engaged by said holder adjacent said depending position.

33. In a circuit interrupter, a tubular enclosure of insulating material having terminals adjacent opposite ends thereof, a line contact, means mounting said enclosure for movement of one of its terminals into and out of engagement with said line contact, latch means for releasably maintaining said enclosure terminal in engagement with said line contact, conducting means in said enclosure connecting said terminals including circuit interrupting means having a movable rodlike member normally restrained against move ment but released for movement upon a circuit interrupting operation, and biasing means for moving said rod-like member to a position wherein a portion thereof projects from one end of said enclosure upon a circuit interrupting operation of said circuit interrupting means, to release said latch and permit movement of said enclosure to disengage said one terminal thereof from said line contact.

34. In a circuit interrupter, an elongated tubular enclosure having circuit interrupting means therein connected between spaced terminals on said enclosure, an electric circuit in which said interrupter is adapted to be connected, means pivotally mounting said enclosure so that the interrupter is movable into and out of said circuit, means for releasably maintaining said interrupter in closed circuit position including a latch member engageable with said enclosure and mounted for limited movement in a first direction toward a latch engaging part of said enclosure, and in a second direction to move said enclosure to open circuit position, means resiliently biasing said latch member in said two directons, latch means normally preventing movement of said latch member in said second direction, and means responsive to a circuit interrupting operation of said interrupting means for releasing said latch means to permit said biasing means to move said latch member in said second direction and said enclosure to open circuit position.

35. In a line contact construction, a line terminal, a floating contact member on said line terminal, means electrically connecting said contact member and line terminal, means biasing said contact member relative to said terminal with a force having a component in one direction to cause engagement of said contact member with a cooperable contact means, and a second component in a direction to cause movement of said floating contact member in another direction away from said terminal, cooperating abutments on said floating contact member and line terminal, respectively, for normally opposing said second force component, and one of said abutments being releasable to permit movement of said floating contact member away' from said line terminal.

36. In a line contact construction, a line terminal, a floating contact member on said line terminal, means electrically connecting said contact member and terminal, means biasing said contact member with a force having a component in a direction to cause engagement of said floating contact member with a cooperating contact means, and a second component in another direction to cause movement of said floating contact member away from said line terminal, releasable abutment means normally opposing said second force component, whereby upon release of said abutment means said biasing means is operable to move said floating contact member away from said line terminal, and means for limiting movement of said floating contact member under the influence of said first force component to maintain said contact in a position to be engaged by said cooperable contact means.

37. In a line contact construction, a line terminal, a floating contact member on said line terminal, means electrically connecting said contact member and terminal, means biasing said contact member with a force having a component in a direction to cause engagement of said floating contact member with a cooperating contact means, and a second component in another direction to cause movement of said floating contact member away from said line terminal, releasable abutment means normally opposing said second force component, whereby upon release of said abutment means said biasing means is operable to move said floating contact member away from said line terminal, and means movably supporting said floating contact member on said line terminal when said abutment means is released, to retain said floating contact member in operative position for engagement by said cooperating contact means.

38. In a contact construction, a contact member mounted at least for pivotal movement on a contact support, a coil compression spring biasing said contact member for movement in one direction relative to said support, and means on said contact and support'for engaging and positioning said spring including integral lugs over which the ends of said spring are adapted to be seated, and rounded projections at opposite sides of each lug for-engaging the end coils of said spring, whereby said contact is movable relative to said support without distorting said spring.

39. In a circuit interrupter having a pair of terminals, arcing contacts at least one of which is movable away from the other to draw an arc, said contacts connected with said terminals, respectively, biasing means for moving said movable contact away from the other of said contacts, electroresponsive means for maintaining said contacts against separation but operative to release said contacts in response to predetermined electrical conditions, the connection of said movable contact and its corresponding terminal including a contact member electrically connected with said terminal, said contact member normally frictionally engaging between said movable arcing contact and the part of said biasing means which is movable with said movable arcing contact, whereby said biasing means is normally effective to maintain pressure engagement of said contact member and movable arcing contact, and disengagement thereof is effected when said contacts separate.

40. In a circuit interrupter having a pair of terminals, arcing contacts at least one of which is movable away from the other to draw an are, said contacts connected with said terminals, respectively, biasing means for moving said movable contact away from the other of said contacts, electroresponsive means for maintaining said contacts against separation but operative to release said contacts in response to predetermined electrical conditions, the connection of said movable contact and its corresponding terminal including a contact member electrically connected with said terminal, and a cooperating contact surface on said movable arcing contact disposed at an acute angle to the direction of movement of said movable arcing contact, said contact member normally frictionally engaging nals being electrically connected to one of said tube terminals, spring means in said tube tensioned between said movable arcing terminal and said other tube terminal, conducting means in said tube extending from said other tube terminal and having a connection with said movable arcing terminal which is separable upon movement of said terminal by said spring means, said spring means and separable connection constituting the sole conducting paths between said other tube terminal and movable arcing contact, whereby said spring means carries the current to said movable arcing contact during arcing.

42. In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends thereof, a line contact, means mounting said tube for movement of one of its terminals into and out of engagement with said line contact, latch means for releasably maintaining said tube terminal in engagement with said line contact, conducting means in said tube connecting said terminals including fusible means and a movable rod-like arcing contact, said rod-like arcing contact normally spaced a predetermined distance from at least one end of said tube, and biasing means for moving said'arcing contact to a position wherein an end portion thereof projects from said one end of said tube upon fusion of said fusible means, to release said latch means and permit movement of said tube to disengage said tube terminal from said line contact only after said arcing contact has moved at least said predetermined distance.

43. In a fuse, a fuse tube of insulating material having terminals adjacent opposite ends thereof, conducting means in said tube connecting said terminals including fusible means, a line contact, means pivotally mounting said tube for movement from a substantially upright position wherein one terminal thereof is in engagement with said line contact to a depending position wherein said one terminal thereof is out of engagement with said line contact, releasable latch means for latching said tube terminal in engagement with said line contact, means responsive to fusion of said fusible means to release said tube terminal for movement out of engagement with said line contact, means for releasably maintaining said tube in a position intermediate said upright and depending positions, and resilient stop means for limiting movement of said tube at said depending position,

44. In a line contact construction, a line terminal, a floating contact member on said line terminal, means electrically connecting said contact member and line terminal, spaced means mechanically supporting said contact member on said terminal, means biasing said contact member in one direction, at least one of said spaced between said contact surface and the part pr" supporting means permitting limited motion of said biasing means which is movable with said movable arcing contact, whereby said biasing means is normally effective to maintain pressure engagement of said contact member and contact said contact member by said biasing to exert contact pressure, and the other of said supporting means being releasable to permit said biasing means to move said contact member in a different direction. 7

45. In a line contact construction, a line ter- 41. In a fuse, a replaceable fuse unit which is na a floating tac m mber on Said line terminal, means electrically connecting said contact member and line terminal, spaced means mechanically supporting said contact member on said terminal, means biasing said contact member in one direction, at least one of said spaced supporting means permitting limited motion of said contact member by said biasing to exert contact pressure, the other of said supporting means being releasable to permit said biasing means to move said contact member in a different direction, and said releasable supporting means automatically resetting in response to predetermined movement of said contact member in the opposite direction.

46. In apparatus of the type described, relatively angularly movable members, a coil compression spring biasing said members for relative movement, means on each of said members for engaging and positioning said spring to prevent lateral spring movement and spring distortion upon relative movement of said members including rounded projections engaging end coils of said spring.

4'7. In apparatus of the type described, relatively angularly movable members, a coil compression spring biasing said members for relative movement, means on each or said members for engaging and positioning said spring to prevent lateral spring movement and spnng distortion upon relative movement of said members including limited area projections engaging end coils of said spring, said projections formed to present substantially line slitt -engaging surfaces extending. substantially transversely of the plane of relative movement or said members.

48. In a circuit interrupter which is adapted to be replaced in its entirety after a circuit in terrupting operation, comprising, in combination, a tube of insulating material, a filler for one end of said tube occupying a substantial part of the length of said tube and comprising a solid insulating material which is capable of evolving an arc-extinguishing gas when in proximity with an electric arc, a restricted bore through said filler, terminal caps secured on each end of said tube. a rod of conducting material in said bore, means connecting one end of said rod to the terminal cap at said one end of said tube, said connecting means being automatically responsive to currents above a predetermined magnitude to release said rod, a relatively thin memberot conducting material in said tube connected to the other terminal cap and extending in engagement with the inner wall of said tube along the remaining length of said tube into proximity with the other end of said rod, a separable electrical connection between said rod and the inner end of said conducting member, a tensioned spring also connecting said rod and other terminal cap, and said spring and conducting member constituting the sole electrical connections between said rod and other cap, whereby upon an automatic circuit interrupting operation said spring separates said separable connection and draws the rod through said bore while all the arcing current is carried by said spring.

49. In a circuit interrupter which is adapted to be replaced in its entirety after a circuit interrupting operation, comprising, in combination, a tube of insulating material, a filler for one end of said tube occupying a substantial part of the length of said tube and comprising a solid insulating material which is capable of evolving an arc-extinguishing gas when in proximity with an electric arc, a restricted bore through said filler, terminal caps secured on each end of said tube, a rod of conducting material in said bore, means connecting one end of said rod to the terminal cap at said one end of said tube, said connecting means being automatically responsive to currents above a predetermined magnitude to release said rod, a relatively thin member of conducting material in said tube connected to the other terminal cap and extending in engagement with the inner wall or said tube along the remaining length oi. said tube into proximity with the other end of said rod with said gasevolving material held against longitudinal movement between said one terminal cap and the inner end of said conducting member, a separable electrical connection between said rod and the inner end of said conducting member, a tensioned spring also connecting said rod and other terminal cap, whereby upon an automatic circuit interrupting operation said spring separates said separable connection and draws the rod through said bore to extinguish the arc.

50. In a circuit interrupter which is adapted to be replaced in its entirety after a circuit interrupting operation, comprising, in combination, a tube of insulating material, a filler for one end of said tube occupying a substantial part of the length of said tube and comprising a solid insulating material which is capable of evolving an arc-extinguishing gas when in proximity with an electric arc, a restricted bore through said filler, terminal caps secured on each end of said tube, a rod of conducting material in said bore. means connecting one end of said rod to the terminal cap at said one end of said tube, said connecting means being automatically responsive to currents above a predetermined magnitude to release said rod, a relatively thin tubular member of conducting material in said tube connected to the other terminal cap and extending in engagement with the inner wall of said tube along the remaining length of said tube into proximity with the other end of said rod, a separable electrical connection between said rod and the inner end of said conducting member, and a coil tensioned spring occupying the space within said tubular member and connected between said other terminal cap and rod to separate said separable connection and draw the rod through said bore upon release of said rod by said current responsive means.

51. In a circuit interrupter .which is adapted to be replaced in its entirety after a circuit interrupting operation, comprising, in combination. a tube of insulating material, a filler for one end of said tube occupying a substantial part of the length of said tube and comprising a solid insulating material which is capable of evolving an arc-extinguishing gas when in proximity with an electric arc, a restricted bore through said filler, terminal caps secured on each end of said tube, a rod of conducting material in said bore, means connecting one end of said rod to the terminal cap at said one end of said tube, said connecting means being automatically responsive to currents above a predetermined magnitude to release said rod, a relatively thin tubular member of conducting material in said tube connected to the other terminal cap and extending in engagement with the inner wall of said tube along the remaining length of said tube into proximity with the other end of said rod, a separable electrical connection between said rod and the inner end of said conducting member, a coil tensioned spring occupying the space within said tubular 25 member and connected between said other terminal cap and rod'to separate said separable connection and draw the rod through said bore upon release of said rod by said current responsive means, and permanent mounting terminal fixtures releasably secured to said terminal caps, respectively, for supporting said interrupter and electrically connecting said terminal caps to circuit contacts.

52. In a circuit interrupter which is adapted to be replaced in its entiret after a circuit in terrupting operation, comprising, in combination, a tube of insulating material, a filler for one end of said tube occupying a substantial part of the length of said tube and comprising a solid insulating material which is capable of evolving an arc-extinguishing gas when in proximity with an electric arc, a, restricted bore through said filler, terminal caps secured on each end of said tube, a rod of conducting material in said bore, means connecting one end of said rod to the terminal cap at said one end of said tube, said connecting means being automatically responsive to currents above a predetermined magnitude to release said rod, a relatively thin member of conducting material in saidtube connected to the other terminal cap and extending in engagement with the inner wall of said tube along the remaining length of said tube into proximity with the other end of said rod, a separable electrical connection between said rod and the inner end of said conducting member, a coil tensioned spring occupying the space within 'said tubular member and connected between said other terminal cap and rod to separate said separable connection and draw the rod through said bore upon release of said rod by said current responsive means, each of said terminal caps having a central opening, a, displaceable closure for each of said openings, and means responsive to a circuit interrupting operation for displacing said closures.

53. In a circuit interrupter which is adapted to be replaced in its entirety after a circuit interrupting operation, comprising, in combina tion, a tube of insulating material, a filler for one end of said tube occupying a substantial part of the length of said tube and comprising a solid insulating material which is capable of evolving.

an arc-extinguishing gas when in proximity with an electric arc, a restricted bore through said filler, terminal caps secured on each end of said tube, a rod of conducting material in said bore, means connecting one end of said rod to the terminal cap at said one end of said tube, said connecting means being automatically responsive to currents above a predetermined magnitude to release said rod, a relatively thin member of cone ducting material in said tube connected to the other terminal cap and extending in engagement with the inner wall of said tube along the remaining length of said tube into proximity with the other end of said rod, a separable electrical connection between said rod and the inner end of said conducting member, a coil tensioned spring occupying the space within said tubular member and connected between said other terminal cap and rod to separate said separable connection and draw the rod through said bore upon release of said rod by said current responsive means, said one terminal cap having an opening through which one end of said rod is projected only after said rod has moved through substantially the entire length of said bore.

54. In a circuit interrupter, spaced line contacts, a renewable interrupter adapted to be connected to said contacts and to automatically move out of engagement with at least one of said contacts in response to a circuit interrupting operation, said interrupter comprising a tubular enclosure of insulating material having terminals mounted thereon at opposite ends with said terminals connected by interrupting means within said enclosure, said interrupting means being automatically responsive to currents above a predetermined value to interrupt the circuit, permanent mounting terminal fixtures releasably secured to said terminals, respectively, one of said fixtures having means for supporting said interrupter for movement of at least one of said terminals into and out of engagement with one of said contacts, one of said fixtures and contacts having cooperating means for latching said interrupter in closed circuit position wherein said terminals are held in engagement with said contacts, and means responsive to an automatic circuit interrupting operation of said interrupter to release said latch means and permit said interrupter to drop out of the circuit.

55. In a circuit interrupter, spaced line contacts, a renewable interrupter adapted to be connected to said contacts and to automatically move out of engagement with at least one of said contacts in response to a circuit interrupting operation, said interrupter comprising a tubular enclosure oi insulating material having terminals mounted thereon at opposite ends with said terminals connected by interrupting means within said enclosure, said interrupting means being automatically responsive to currents above a predetermined value to interrupt the circuit, permanent mounting terminal fixturesreleasably secured to said terminals, respectively, one of said fixtures having means for pivotally supporting said interrupter on one of said contacts for movement of the other terminal into and out of engagement with the other contact, the other of said fixtures and contacts having cooperating means for latching said interrupter in closed circuit position wherein said terminals are held in engagement with said contacts, and means responsive to an automatic circuit interrupting operation of said interrupter to release said latch means and permit said interrupter to drop out of the circuit.

56. In a circuit interrupter, interrupting means having a terminal, a terminal fixture adapted to be secured to said terminal, said fixture including a part having an opening of a size to freely receive said terminal, a cooperating part adapted to engage one side of said terminal, and screw means for moving said parts relative to each other into clamping engagement with opposite sides 01' said terminal, respectively, to provide a rigid mechanical and good electrical connection of the fixture and terminal.

57. In a circuit interrupter, interrupting means having a terminal, a terminal fixture adapted to be secured to said terminal, said fixture includ- 58. In a circuit interrupter having a pair of terminals, arcing contacts at least one of which is movable away from the other to draw an arc. said contacts connected with said terminals, respectively. biasing means for moving said movable contact away' from the other of said contacts, electroresponsivexmeans for maintaining said contacts against separation but operative to release said contacts in response to predetermined electrical conditions, the connection of said movable contact and its corresponding terminal compris inga solid connection having a relatively weak portion joining a relatively rigid element to one member, and a flexible connection from the other member to said element at a point oil'set from said weak portion in a direction laterally oi the direction of motion of said movable contact, so that said weak portion will be subjected to bending and tensile stress so as to be readily broken by said biasing means in response to a circuit interrupting operation.

59. In a circuit interrupter, a holder tube enclosure of insulating material having terminals adjacent opposite ends thereof, conducting means in said tube connecting said terminals including means automatically responsive to predetermined electrical conditions for interrupting the circuit, a line contact, means pivotally mounting said tube for movement from a substantially upright position wherein one terminal thereof is in engagement with said line contact to 9. depending position wherein said one terminal thereof. is out of engagement with said line contact, releasable latch means for latching said tube terminal in engagement with said line contact, means responsive to a circuit interrupting operation of said interrupting means to release said tube terminal ior movement out of engagement with said line contact, means for releasably maintaining said tube in a position intermediate said upright and depending positions but inefiective to stop movement or said tube on automatic dropout movement thereof.

60. In a line contact construction, a line terminal, a floating contact member on said line terminal, means electrically connecting said contact member and line terminal, a single spring biasing said contact member relative to said terminal with a forcehaving a component in one direction to cause engagement of said contact member with a cooperable contact means, and a second component in a direction to cause movement of said floating contact member in another direction away from said tenminal, cooperating abutments on said floating contact member and line terminal, respectively, for normally opposing said second force component, and one of said abutments being releasable to permit movement of said floating contact member away from said line terminal.

HERBERT L. RAWLINS. JOHN J. MZIKOS.

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