US2651695A - Circuit interrupter - Google Patents

Description

Sept. 8, 1953 c. H. BAKER 2,651,695

CIRCUIT INTERRUPTER Filed May 22, 1950 4 Sheets-Sheet l Z2 /4 a2 i /0 23 5 /8 f Z] r o l i i I I I 25 I v Z6 19 1 1 F i! 5 I w i i i ,l i 239 g Lg W 1 I 1 I I I INVENTOR.

Chi/Z9617 252/661;

KMW

Sept. 8, 1953 I c. H. BAKER 2,651,695

CIRCUIT INTERRUPTER Filed May 22, 1950 4 Sheets-Sheet 4 H II Patented Sept. 8, 1953 CIRCUIT INTER-RUPTER Charles H. Baker, Maywood, 111., assignor to S & C Electric Company, Chicago, 111., a corporation of Delaware Application May 22, 1950, Serial No. 163,511

16 Claims.

This invention relates, generally, to circuit interrupters and it has particular relation to dropout fuses.

Among the objects of this invention are: To provide a simple and economical dropout fuse construction of the solid material type; to construct the unlatching mechanism of a dropout fuse in such manner that a coil compression spring therein is not distorted when the device is automatically unlatched on blowing of the fuse; to secure a detachable hinge fitting to the lower ferrule of a dropout fuse tube by a U-bolt; to secure a detachable latch terminal fitting to a radial flange at the upper end of the dropout fuse tube;

to utilize both ends of the power spring to perform useful functions; to maintain contact engagement between contact fingers within the fuse tube arranged to engage a movable rod-like terminal and a conducting tube therein by means of the spring that retracts the rod-like terminal when the fuse blows; to insulate the spring from the rod-like terminal so that no current flows therethrough; to maintain a fixed air gap between the'conducting tube and the movable rod-like terminal while the latter is being withdrawn; to provide for assembling the aforesaid internal mechanism in a fuse tube; and to provide for connecting fusible cans to the upper end of a conducting tube which is located at the lower end of the fuse tube.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

The invention is disclosed in the embodiment thereof as shown in the accompanying drawings and it comprises features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and the scope of this invention reference can be had to the following detailed description, taken together with the accompanying drawings, in which:

1 is a View, in side elevation, of a dropout fuse construction in which the present invention is embodied, certain parts being broken away and other parts being shown in section in order to illustrate more clearly the details of construction;

Figs. 2A.2B-2C placed one above the other show at an enlarged scale a longitudinal section of the fuse construction shown in Fig. 1, certain parts being shown in elevation;

Fig. 3 is a View, similar to Fig. 2B, and showing a modified construction;

at an enlarged scale a modified form of contact construction.

The construction of the fuse tube and operating mechanism is somewhat similar to that disclosed in the copending application of Lindell and Baker,

, Serial No. 663,832, filed April 22, 1946, now abandoned, and assigned to the assignee of this applisigned to the assignee of this application are employed. The features of the contact construction and mounting therefor shown in the co-pending application of Lindell, Serial No. 57,346, filed October 29, 1948, now U. S. Patent No. 2,578,255, dated December 11, 1951, and assigned to the assignee of this application also are used in conjunction with the present invention.

Referring now particularly to Fig. 1 of the drawings it will be observed that the reference character 19 designates, generally, a dropout fuse construction which is intended for use on circuits energized at a voltage of 69 k. v. This voltage is mentioned for illustrative purposes since the present invention can be adapted for use on systems operating at higher or lower voltages. The dropout fuse construction [0 is mounted on a channel base I l which carries upper and lower insulator stacks l2 and I3 near its ends. A latch terminal construction, shown generally at I 4, is carried by the upper insulator stack 52 while a hinge terminal construction, shown generally at I5, is carried by the lower insulator stack IS. The latch and hinge terminal constructions l4 and 15 preferably are constructed as disclosed in the aforesaid co-pending U. S. Patent No. 2,578,255 so that the fuse tube described hereinafter can be employed in conjunction therewith in lieu of the fuse tube disclosed in this co-pending application.

The latch terminal construction [4 includes a pivotally mounted latch I6 which carries a roller [1. The roller I? is arranged to cooperat with a roller i8 that is .carried by a latch arm I9 for the purpose of holding the fuse tube in operative position. The latch arm it constitutes a part of a detachable latch terminal fitting that is shown, generally, at 25. Extending upwardly from the fitting 2i! is a guide tube 2! on which is telescoped an unlatching tube 22. This construction is illustrated in more detail in Fig. 2A. The tube .22 has an outwardly extending radial flange itatits lower end which is arranged to engage the bifurcated forward end 2 of the latch it for raising the roller it out of the path of the roller 8 to permit the fuse tube to swing to the open circuit position. As will be described hereinafter, this action takes place when the tube 22 is moved upwardly on blowing of the fusible element and after the current flow has been interrupted. At the forward end of the fitting 20 an eye 25 is rockably mounted at 2% and a pair of arms 27! extend therefrom underneath the flange 23. The purpose of this construction is to provide for receiving the prong of a live line tool for swinging the fuse tube to the closed position or for manually unlatching it if desired. A contact member forming a part of the latch terminal construction it is arranged to have contact engagement with the fitting 26 for conducting current thereto. Preferably the contact member 28 is constructed as disclosed in the co-pending U. Patent No. 2,578,255.

The detachable latch terminal fitting and parts carried thereby are mounted on the upper end of a fuse tube that is indicated, generally, at Except as described herein, the fuse tube 29 preferably is constructed as disclosed in the co-pending application of Lindell and Baker, Serial No. 663,832, now abandoned. However, other constructions can be. employed desired without departing from the scope of the present invention.

At its lower end the fuse tube '29 is rockably l mounted on a hinge member Iii which forms a part of the hinge terminal construction iii. For this purpose trunnions 32 project from opposite sides of a detachable hinge fitting that is indicated, generally, at 33, The detachable hinge fitting tthasan arcuate seat portion for receiving a cylindrical lower ferrule to which it is clamped by means or a U-bolt Suitable dowel pin means are provided for insuring proper alignment of the hinge fitting 33 on the ferrule 34 with thefitting 25) at the upper end of the fuse tube 2%. The hinge fitting 33 includes an eye 36 for receiving the prong of a live line too1 to permit handling of the fuse tube 29. A contact member 31, preferably constructed as disclosed in the aforesaid co-pending U. S. Patent No. 2,578,255, provides contact engagement with the hinge fitting 33. Also included with the hinge member 33 is a rubber bumper 38 for partly absorbing th shock incident to the stopping of the fuse tube 29 when it swings downwardly.

Referring now particularly to Fig. 2A, it will be observed that the fuse tube 29 comprises a tube iii of insulating material, preferably a phenolic condensation product. At its upper end the tube El has an upper metallic ferrule 62 which is secured in position by having its intermediate portion Q3 rolled into a suitable annular groove in periphery with the upper end of the tube 4|. The upper end M is spun over a flange 45 which forms a part of an upper terminal ring 15. The ring 26 has a radial flange 4"! at its upper end that projects into a recess 68 on the underside of the central portion 65 of the detachable latch terminal fitting 2t. Bolts 5% and bi, extending parallel to the longi tudinal axis of the fuse tube 29, project through the central portion 9 into threaded engagement with the radial flange .71. This construction permits the fitting 25 and parts attached thereto to be reused with another fuse tube 29 cnce the fuse has blown or it is desired to use another fuse tube for some reason. The bolts tit and bl also serve to clamp a flange 52 between the central portion 59 and the upper surface of flange ll and provide alignment the fitting with the hinge fitting 33 and axial alignment with th fuse tube 29. The flange constitutes an integral extension of a conducting tube 53 which extends downwardly into the tube ii for the purpose of providing a current conducting path to the mechanism that is illustrated more clearly in Fig. 2B of the drawings.

Still referring to Fig. 2A of the drawings, it will be observed that a shoulder 5%; is formed on the guide tube 26 and that the radial fiange 23 is held in engagement therewith by a coil compression spring 5i. The lower end of the spring El bears against an upstanding part of the fiange as shown, and its upper end. bears against the under side of a collar tit which is secured to the upper end of the guide tube 2!. described hereinafter, when the fuse blows, a member moves upwardly through th guide tube 2i and engages a cap 59 which is carried at the upper end of the unlatchlng tube 22. This lifts the flange for raising the latch is in a manner previously described. It is desirable to prevent the spring 5'1? from being distorted which might be the case when the unlatching tube is moved upwardly under considerable force. Unless means are provided for preventing such distortion, the spring 5% may go solid and may be permanently distorted so that it would not be reusable. For this purpose a stop sleeve Si? is located in the space between the telescoped tubes 2i and 22. The length of the stop sleeve 65} is such that the tubes 21 cannot be moved far enough apart to permit the spring 5'5 to go solid.

Referring now to the portion of the construction illustrated in Fig. 213, it will be observed that the tube ii is provided with a liner 63 for reinforcing the same. Preferably the liner 63 is formed of fiber. Within the liner t3 cakes E4 of arc extinguishing material, such as boric acid, are inserted, preferably as disclosed in the copending application of Lindeli and Baker, Serial No. 663,832, now abandoned. The cakes 5d of arc extinguishing material are apertured to provide a longitudinally extending bore 8% through which a rod-like terminal as is longitudinally movable. At the upper end of the liner 63 a reinforcing ring til is located. Preferably it is formed of fiber and is threaded into the liner At it upper end the rod-like terminal 86 has a nut 58 on a threaded extension 69. The purpose of this construction will be described presently. The nut 58 has a cylindrical contact surface '38 that is arranged to be engaged by contact fingers l l. The diameter of the cylindrical contact surface it is greater than that of the rod-like terminal 6% to permit free movement of the latter past the contact fingers The upper ends '52 of the contact fin ers ii are curved to provide a convex contact surface for engaging the cylindrical contact surface it on the nut 69 while the other side is concave for receiving a garter spring 13 which urges the upper ends of the contact fingers H and 22- into good contact engagement with the contact surface 79. The contact fingers H are formed in a tubular member of good conducting material which has resilient characteristics. The contact fingers l'l extend upwardly from a cylindrical base portion M which has an outstandin radial fiange that overlies and is in contact engagement with the upper surface of a radially inwardly extending fiange 16 formed integrally with the conducting tube 53 at its lower end.

The flange "i5 is loosely mounted on the flange l9 and they are held in good contact engagement by means of a coil compression spring 17 which also acts to move the rod-like terminal 68 upwardly when the fuse blows. At its lower end the spring 17 reacts against the upper side of the flange i5 and at its upper end it bears against the under side of an insulating washer or head member 78. Preferably the washer 18 is formed of good insulating material such as a phenolic condensation product. It is provided to prevent any current flowing through the spring 17 which, particularly under short circuit conditions, might be sufficient to anneal the convolutions thereof and prevent it from biasing the rod-like terminal in the manner described. The insulating washer it has a hexagonal opening 19 in its under side for telescoping with the upper end of a hexagonally shaped arcing rod extension 89. The lower end 81 of the arcing rod extension 89 is threaded on the extension 89 and locked against the upper side of a hexagonal head or flange 68 which is formed integrally with the nut 98. At its upper end the arcing rod extension 89 has a threaded shank 82 on which a hexagonal nut 83 can be threaded for holding the insulating washer l8 in position. The nut 83 interfits with a hexagonal opening 83' in the upper side of the washer '13 to prevent relative turning. Openings 3d are provided in the upper surface of the insulating washer 9 for receiving a spanner wrench. The manner in which the mechanism within the tube H is assembled will be described hereinafter.

In Fig. 2C of the drawings the details of construction of the lower end of the fuse tube 29 are illustrated more clearly. It will be observed that the liner 53 extends to the extreme lower end of the tube 5!. Below the lowermost cake 64 of arc extinguishing material throat members 88 and 99 are positioned. The member 88 is formed preferably of boric acid and the member 89 of fiber.

At the lower end of the rod-like terminal 66 fusible means, shown generally at 99, are connected. The fusible mean 99 includes a strain element 9| and a fusible element 92. Where the fuse is to be employed in a circuit in which the normal current flow is of the order of only a few amperes, then the strain element 9| only need be employed. Where the fuse is intended to conduct higher currents the fusible element 92, which may be formed of silver, also is employed. The strain element 9| is looped over a transverse pin 99 which is carried by a relatively thick walled metallic terminal tube 94. A stud 95 projects radially inwardly from the terminal tube 94 for receiving one end of the fusible element 92 if the same is used.

The terminal tube 94 is located at and carried by the upper end of a conducting tube 96 the purpose of which is described in the co-pending application of Lindell and Baker, Serial No. 663,832, now abandoned. The lower end 91 of the conducting tube 95 is flared outwardly and is secured by rivets 98 to the inwardly flared lower end 99 of the lower ferrule 34. It will be observed that the ferrule 34 has an annular groove I00 intermediate its ends for securing it to the tube 4| and for locating and centering the U=bolt 35.

The manner in which the fuse tube 29 and parts associated therewith are assembled will now be described. The lower and upper ferrules 34 and 42 are secured to the ends of the tube 4| by a rolling operation. Next the cakes 64 of arc extinguishing material are inserted. Thereafter the reinforcing ring 61 and the throat members 88 and 89 are placed in position.

Prior to assembly with the tube 4| the lower conducting tube 96 is attached to the metallic terminal tube 94.

The transverse pin 93 is inserted in the tube 94 through the loop in the strain wire 9|. The stud 95, with one end of the fusible element 92 attached thereto, is riveted in position in the wall of the tube 94. The lower end of the rod-like terminal 58 is secured to the upper ends of the strain wire and the fusible element 92. This complete assembly then is dropped into the tube 4| in the upsidedown position. The lower end 9'! of the conducting tube 96 is secured by the rivets 98 to the lower end 99 of the lower ferrule 35.

Outside of the tube 4| the upper terminal ring as is assembled with the upper end of the conducting tube 59. This assembly is then inserted in the upper end of the tube 4| and the upper end of the upper ferrule 42 is spun over the flange 45%. The contact fingers 1| now are placed in the lower end of the upper conducting tube 53. Then the nut 68 is threaded onto the extension 99 by means of a tubular socket wrench which is large enough to accommodate the hexagonal head 68. The threads on the nut 68 and extension 69 are free running so that there is no tendency to twist the rod-like terminal 66 while the nut 88 is being turned down. It is undesirable to twist the rod-like terminal 89 in order that any undue stress on the strain element 9| and the fusible element 92 is avoided. Now the hexagonally shaped arcing rod extension 89 is inserted through the tubular wrench which is holding the head 68 of the nut 58. The area of the wrench holding the hexagonal head 58' isv such that another socket wrench can be telescoped therewith for the purpose of threading the free running extension 89 onto the threaded extension 99. Initially the nut 98 is screwed down so that its lower end lightly abuts the upper end of the large diameter portion of the rod-like terminal 69. After the arcing rod extension has been threaded into position, where its threaded opening bottoms on the upper end of the extension 69, the nut 93 is backed off until it is locked in engagement with the lower end of the arcing rod extension as. This is accomplished by holding stationary the wrench which grips the arcing rod extension 88 and rotating the wrench which grips the head 83 of the nut 68.

Now the coil compression spring 17 is inserted so that its lower end engages the upper surface of the flange 15. The spring 1'! is compressed by inserting the insulating washer 18 until it is stopped by the upper end of the arcing rod extension 88 with the shank 82 projecting therethrough. A spanner wrench is inserted in the openings 89 to hold the washer 18 stationary while the nut 83 is applied to the threaded end of the shank 82 by a tubular socket wrench. This avoids turning of the rod-like terminal 66 and parts attached thereto. On release of the washer l! 1 N3, the spring 1'! moves it upwardly slightly so that the nut 83 interfits with the hexagonal socket 553. This completes the assembly of the fuse tube 29. When assembled as described equal forces at the ends of the power spring ii are applied through the rod-like terminal it to the strain element 9! at one end and to the flange E5 of the contact fingers ii at the other end, thereby providing contact pressure with the flange 76. Now it will be understood that it can be assembled with the latch terminal fitting 253 at the upper end and the hinge fitting 33 at the lower end for mounting in a dropout fuse mounting.

In operation, when the fusible means to blows, the rod-like terminal as no longer is restrained. Since the pin 93 the stud are secured to the tube 9 B, there are no parts which are expellable downwardly. The coil compression spring ll expands and withdraws the rod-like terminal 65 upwardly to a position where its lower end may be located along the brolren line iii! in Fig. 2B. Before the lower end of the rod-like terminal .66 reaches this position the upper end of the shank 82 en ages the underside of the cap and moves the unlatching tube 22 upwardly. This moves the radial flange 23 in the same direction and lifts the latch The roller ii is moved out of the pathof the roller whereupon the fuse tube 29 can swing about the hinge member 3i downwardly to provide an an gap in the circuit in addition to the gap which is provided within the fuse tube 29.

As soon as the nut 58 moves upwardly so that its contact surface "it no longer the upper ends '12 of the contact fingers ii, an arc is drawn between the contact fingers "ii and the rod-lilac terminal 66 unless itso happens that the surface of the rod-like terminal t6 bears against one of the contact fingers it. As will appear hereinafter provision is made for fixing the length of such an are so that it is not left as a somewhat indeterminate matter as is the case when the construction illustrated in Fig. 2B is employed.

Referring now particularly to Fig. 3 of the drawings there is illustrated a construction which may be employed in lieu of that illustrated in Figure 23. If it is desired to fasten the flange It at the lower end of the contact fingers H to the flange to take'care of higher current ratings, this may be accomplished by means of rivets act, which, as illustrated, extend through the flanges l5 and it and hold them securely together. Instead of employing the rod-like terminal with the arcing rod extension til, a single continuous rod-like terminal i 5 is employed. It has a contact sleeve tilt having a press fit with a knurled portion Hit of the rodlike terminal Hi5 as shown, for engaging the upper ends iii of the contact fingers ii. The rod-like terminal 35 projects through an insulating washer Hill which holds the spring ill in compressed condition. A snap ring let interfits with the upper endof the rod-like terminal 1.65 and holds the insulating washer it'll in the position shown.

In Fig. i of the drawings there is shown a construction which can be employed for fastening to the lower end of the fusible means in lieu of that illustrated in Fig. 2C. As shown in Fig. 4

a bridgeinember ill bears against the lower end of the metallic terminal tube to. It carries a stud i 52 to theupper end of which the lower ends of thestrain element iii and fusible element .92 are secured. Nuts 9 it are threaded .on the lower end of the stud .112 to secure itin position on the br dge me ber It W l be understood that the alternate construction illustrated in Fig. 4.- can be emplo d n c mmo ion w alternate c nstruction shown n 3 r h it can be employed in lieu of the construction illustrated in Fig, 2G in conjunction with the construction illus ra ed in .F s,

In g. 5 of the drawings an alternate construction is illustrated which may be employed in lien 01 those illustrated in Figs. 23 and 3. As there shown, a rod-like terminal HE is arranged to be moved endwise through the bore he formed the cakes 6 of arc extinguishing material. Also it moves through a reinforcing ring i ll. At its upper end the rod-like terminal lit has a threaded extension i is which is screwed into the lower enlarged end 1 IQ of an arcing rod extension iZil. At its upper end the arcing rod extension in has a threaded shank lil which projects through an insulating washer it against which the upper end of the coil compression spring ll reacts. A nut M3 is threaded on the shank it! for securing the washer 522 in position. The lower end I 19 of the arcing rod exten sion ifil has a cylindrical contact surface 525 that is arranged to have contact engagement with annularly curved portions lid of generally sector shaped contact members H26 shown more clearly in Fig. .6 of the drawings. The contact members four in number, have flange portions iZi which slide radially over the flange it at the lower end of the conducting tube 53. As shown by the upper two contact members 525 in Fig. 6, their radial inward movement is limited by their engaging radial sides to provide ample clearance for the rod-like terminal HE. A garter spring laid, surrounding the annularly curved portions acts to bias the inner surfaces thereof into good contact engagement with the cylindrical contact surface if l. As described hereinbefore in connection with Fig. 2B, the spring provides contact pressure between the flange portions it? and the flange l6.

It is desirable, as pointed out previously, to provide a fixed gap for the are which is formed when the rodel-ike terminal, such as the terminal H6, moves out of engagement with the contact members, such as theannularly curved portions i 535 of the contactmembers [26. For this purpose a metallic washer i253 is positioned on the upper end of the reinforcing ring ill underneath the flange H5 and in contact engagement therewith. Now, when the contact surface 124 moves out of engagement with thecurved portions Hit, a fixed gap 530 will be maintained with the rod-like terminal i it as it is withdrawn through the bore 55 by the coil compression spring Ti.

Since certain further changes can be in the foregoing construction and different embodirnents of .the invention canbe made without departing from the spirit and scope thereof, it is intended that all matter shown in the accompanyin drawings and described hereincefore shall be interpreted as illustrative and not in a limiting sense.

What is claimedas new is:

1. In a fuse construction, in combination, a fuse tube, ferrules at the ends of said fuse tube, fusible ineanswithin said fuse tube connected to one ferrule, a movable rod-like terminal connected to said fusible means and extending toward the other ferrule, a conducting tube ccnnested at oneend to the .otherferrule and extending into said fuse tube past said rod-like terminal, a flange extending radially inwardly from the other end of said conducting tube, contact finger means loosely fitting against said flange and biased into contact engagement with said rod-like terminal, and a coil compression spring reacting between said rod-like terminal and said contact finger means for holding the latter in contact engagement with said fiange and retracting the former on blowing of said fusible means.

2. The invention, as set forth in claim 1, wherein the contact finger means comprises a longitudinally slotted sleeve of resilient conducting material with the free ends of the fingers biased inwardly for contact engagement with the rod-like terminal, said sleeve having a radially outwardly extending flange overlying the radially inwardly extending flange of the conducting tube.

3. The invention, as set forth in claim 1, wherein the contact finger means comprises a plurality of sector shaped contact members radially slidable on the inwardly extending flange of the conducting tube each having an annularly curved portion for engaging the rod-like terminal on one side and for receiving a garter spring on the other, and a garter spring surrounding said curved portions and biasing them inwardly.

4. The invention, as set forth in claim 1, wherein the coil compression spring is insulated from the rod-like terminal so that no current flows through said spring while it is withdrawing said rod-like terminal.

5. The invention, as set forth in claim 1, wherein conducting means extend radially inwardly from the flange on the conducting tube into close proximity to the rod-like terminal during its movement to provide an arcing point at a fixed distance therefrom during such movement.

6. In a fuse construction, in combination, a fuse tube, terminals at the ends of said fuse tube, fusible means within said fuse tube connected at one end to one terminal, a movable rod-like terminal connected at one end to the other end of said fusible means and having a threaded extension on its other end and extending toward the other terminal, a conducting tube connected at one end to said other terminal and extending into said fuse tube past said threaded extension, a nut threaded on said extension having a wrench receiving flange at one end and a body portion providing a cylindrical contact surface, contact means slidably interconnecting said contact surface and the other end of said conducting tube, an arcing rod extension threaded at one end onto said extension into locked engagement with said nut, a head at the other end of said arcing rod extension, and a coil compression spring reacting between said head and said other end of said conducting tube and biasing said rod-like terminal for movement on blowing of said fusible means.

'7. In a fuse construction, in combination, a fuse tube, terminals at the ends of said fuse tube, a thin walled conducting tube connected at one end to one of said terminals and extending therefrom into said fuse tube, a relatively thick walled and short metallic terminal tube telescoped within and secured to the other end of said conducting tube, fusible means connected at one end to said metallic terminal tube, a movable rod-like terminal connected at one end to the other end of said fusible means, conducting means interconnecting the other end of said rod-like terminal to the other terminal, and spring means biasing said rod-like terminal toward said other terminal.

8. The invention, as set forth in claim 7, wherein the fusible means comprises a strain wire and the same is connected to a pin extending trans versely of the metallic arcing tube.

9. The invention, as set forth in claim 7, wherein the fusible means comprises a fusible element and a strain wire, a conducting stud extends radially inwardly from th metallic terminal tube and is connected to said fusible element, and a rod extends transversely of said metallic terminal tube and is connected to said strain wire.

10. The invention, as set forth in claim 7, wherein the fusible means comprises a strain wire, a metallic bridge member bears against the end of the metallic arcing tube within the thin walled conducting tube, and a conducting stud is carried by said bridge member and is secured to said strain wire.

11. In a fuse construction, in combination, a fuse tube, terminals at the ends of said fuse tube, fusible means within said fuse tube connected to one terminal, a movable rod-like terminal connected at one end to said fusible means and extending toward the other terminal, a conducting tube connected to said other terminal and extending into said fuse tube and connected to the other end of said rod-like terminal, and a fiber liner within said fuse tube extending from said one terminal into said fuse tube and juxtaposed to the inner end of said conducting tube.

12. In a fuse construction, in combination, a fuse tube, terminals at th ends of said fuse tube, one of said terminals comprising a ferrule surrounding one end of said fus tube and projecting therebeyond, the projecting portion of said ferrule having one portion extending inwardly to overlie said end of said fuse tube and another portion of cylindrical shape having a diameter less than the outer diameter of said end of said fuse tube, a conducting tube extending into said one end of said fuse tube for a distance several times its diameter and having its outer end secured to said cylindrical portion of said ferrule, fusible means within said fuse tube connected to the inner end of said conducting tube, and a movable rod-like terminal connected to said fusible means at one end and extending toward and connected to the other terminal.

13. In a fuse construction, in combination, a fuse tube, terminals at the ends of said fuse tube, one of said terminals comprising a ferrule surrounding one end of said fuse tube and projecting therebeyond, the projecting portion of said ferrule being offset inwardly to provide a cylin drical outer end portion having a diameter intermediate the inner and outer diameters of said fuse tube, a conducting tube extending into said one end of said fuse tube for a distance several times its diameter and having its outer end offset outwardly and secured to said cylindrical portion of said ferrule, fusible means within said fuse tube connected to the inner end of said conducting tube, and a movable rod-lik terminal connected to said fusible means at one end and extending toward and connected to the other terminal.

14. In a fuse construction, in combination, a fuse tube, terminals at the ends of said fuse tube, fusible means within said fuse tube connected to one terminal, a movable rod-like terminal connected at one end to said fusible means and extending toward the other terminal, a conducting tube connected to said other terminal and exii tending into said fuse tube and connected to the other end of said rod-like terminal, an extension from said other end of said rod-like terminal, an insulating head at the outer end of extension, and a coil compression spring within said fuse tube reacting against said insulating head to tension said fusible means and withdraw said rod-like terminal when said fusible means blows.

15. In a fuse construction, in combination, a fuse tube, terminals at the ends of said fuse tube. fusible means within'said fuse tube connected to one terminal, a movable rod-like terminal eonnected at one end to said fusible means and ex tending toward the other terminal, a conducting tube connected to said other terminal and extending into said fuse tube coextensive with a portion of said rod-like terminal, separable contact means interconnecting the inner end of said conductingtube and said rod-like terminal between Which an arc may be drawnon operation of the fuse, an insulating head on the other end of said rod-lik terminal, and a coil compression spring reacting betweensaid-insulating head and the inner end ofsaid conducting tube to tension said fusible means and withdraw said rod-like terminal when said fusible means blows, said in sulating head preventing the transfer of said are to said other end of said-rod-1ike terminal.

16. In a fuse construction, in combination, a fuse tube, terminals at the ends of said fuse tube, fusible means Within saidfuse tube connected to one terminal, a one-piece movable rod-like terminal connected at one end to said fusible means and extending toward the other terminal, a contact sleevecarried by said rod-like terminal inte'rmediate'its ends; a conducting tube connected to said other terminal and extending into said fuse tube in telescoping relation with said rodlike terminal and beyond said contact sleeve car ried thereby, a contact assembly connected to the inner end or said conducting tube and engagit T said contact sleeve between which an arc be drawn on operation of the fuse, an insula headon'the" other end'of said rod-like ten and a coilcompression spring reacting bem said insulating head and" the inner end of conducting tube-totensionsaid'fusible means a withdraw said rod-like terminal when said usible means blows, said'insulating' head preven transfer ofsaid'arcto said other end'of rodlike terminal.

CHARLES H. BAKER.

References Cited in' the file of this patent UNITED STATES PATENTS Number Name Date 1,192,627 Sargent July 25, 1916 2,259,946 Wallace Oct. 21, lflii 2,318,817 Triplett May 11, 1943 2,333,774 Fahnoe Nov. 9, 194.3 2,337,937 Serfling Dec. 28, 19 .3 2,379,200 Triplett June 26, 1945 2,403,121 Rawlins et a1. July 2, 19-16 2,484,889 Lindell Oct. 18, 19%?) 2,517,624 Baker Aug. 8, 1959 2,567,236 Rawlins'et a1 Sept. 11, 1951 2,567,768 Fahnoeuue Sept. 11, 1951

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