US1203316A - Oil-fuse. - Google Patents

Description

L. W. DWNES.

OIL FUSE.v

APmcATaoN F|LEn1uLY17,1912. RENEWED FEB. 26.1914.

l 203,3 1 6. Patented Oct. 31, 1916.

2 SHEETS-SHEET l.

L. W. DOWNES.

OIL FUSE.

MPL10/111011 r|LED1uLY17.1912. RENEwEu 155.216.1914.

1 203 316. 111116111911 001.. 31, 11116. 5 78 2 SHEETS-SHEET 2.

LOUISW. DOWNES, 0F PROVIDENCE, RHODE ISLAND.

OIL-FUSE.

Specification of Letters Patent.

Application led July 17, 1912, Serial No. 710,044.

To'all whom t may concern e Be it 'known vthat I, Louis W. DowNEs, of Providence, Rhode Island, have invented a new and useful Improvement in Oil-Fuses, which invention is fully set forth in the following specification.

Experience has demonstrated that electric fuses of well-known types which have heretofore given satisfactory operation on single phase high tension circuits are not always sure and satisfactory in their opera.-v tion on the more modern poly-phase systems of electric distribution, and hence with such modern systems have come to be regarded as a source of uncertainty and consequent danger.l

The principal object of the present invention is to provide an electric fuse adapted to serve as a primary and junction cut-out on high tension poly-phase circuits such as those of2,500 bolts or more. That object I believe I have attained by the fuse of the present invention which in its operation is Y adapted to break the circuit in oil, tests and experience with such fuses having yielded satisfactory results under conditions of eX- treme severity and heavy overload.

A further object of the invention is to provide a structure which will prevent the oil in the receptacle or casing from being blown out of said casing under conditions that may be frequently encountered, such discharge or absence of the oil leaving nothing in thel casing to extinguish the arc that might be formed, as the result of which' there would be violent arcing with consequent destruction of or injury to the device. To illustrate, a condition might exist on a circuit supplying lights or power whereby the lines had become short circuited at some distant point, causing immediate blowing of the fuse at the transformer. A lineman going to investigate the trouble might not immediately find the insert a new fuse. In the absence of provision to meet the condition, the instant the new fusel is inserted and its connection in the circuit el'ected-the-trouble still being prcsent-it would be blown by a heavy rush of current through it, and if the cover of the receptacle had not curely fastened, it would be forced olf and a considerable part of the oil immediately blown out of the casing, with the result that dangerous arcing would take place. To meet such .conditions the fuse of my present cause and proceed to been closed and se Patented Got. 31, 1916.

Renewed February 26, 1914. Serial No..821,318.

invention embodies means whereby the cover ofthe casing must be closed and locked before the newly inserted fuse can be connected between the circuit terminals within the caslng. As a suitable way of providing for such closing and locking of the cover before the circuit is completed through the fuse, I have illustrated the employment of a bayonet joint construction to be more fully described in detail hereafter. By such construction and the relative arrangement of the fixed terminalsl within the casing and the contacts on the fuse carrier Y between which the fuse link is connected, the casing cover with the carrier fixed thereto mustbe put in place and then rotated through an.

arc, preferably of approximatelyy 90, before the contacts on the fuse carrier engage the fixed terminals within the casing to complete the circuit through the fuse link. Hence, even if a new a fuse be inserted in a live circuit-one for instance Which has been crossed by another circuit--noA harm can occur to the apparatus or the operator since there is no opportunity for the oil to be blown out. Preferably the oil level is somewhat below the top of the oil chamber in the casing to permit of movement of the oil on the blowing of the fuse. Experience has demonstrated that when such a. fuse is blown under very severe conditions the oil will be driven up against the top of the box with considerable force, but will immediately fall back to the bottom of the casing, any arc that may be formed being promptly extinguished andburning of the fuse 'terminalsl 2 is a horizontal section on line 2-2 of Fig.

l. Fig. 3 is a vertical section on line 3-3 of Fig. 2. Fig. 4 is a horizontal section on line 4-4 of Fig. 1. Fig. 5 is a fragmentary view of the fuse carrier and parts thereon. Fig. 6 is a detail sectional view on line G of Fig. 2. Fig. 7 is a detail sectional vieW on line 7 of Fig. 2. Fig. 8 is a detail view of one of the fuse carrier contacts. Fig. 9 is a detail view of thefuse link of Figs. 1-5. Fig. 10 is a detail view of another form of fuse link. Fig. 11 illustrates the fuse link of Fig. `l() applied to a fuse carrier shown in outline, andv Fig. 12 is a view similar to Fig. 11 but. showing the action or other structure. Terminal 'conductors 22 vand 23 enter said casing by passing upward throughbushings 24, 25, respectively. The conductors make a close lit through the bushings the openings of which are enlarged 'at the upper end and filled with a suitable oil proof cemen-t 24 such as shellac gum poured in while liquid. This seals the cable entrances and prevents escape of oil from the casing at these points. rlFhe bushings are of porcelain or other suitable insulating material and depend through vertical openings in bulges or pockets 26, 27 at opposite sides of the casing. Vertical Hanges or ribs 28 positioned at intervals about the exterior surface of the casing serve in the well known way to lextend the heat radiating i surface and thereby facilitatedissipation of i" the heat developed by the fuse when running under normal conditions ofload The casing is made relatively large to contain a liberal volume of oil and dissipation of heat tions.

is such as to avoid ,any possibility of disintegratlon of the oil and insure a safely low temperature under normal working condi- ()n the inside of the casing the terminal conductors .22 and 23 lead to fixed lspring terminals adapted to coperate with contacts on the fuse carrier as described here- The inner end of conductor 22 is. lsoldered or otherwise electrically connected after.

in a clip 29 which makes electrical contact with one end of a U-shape terminal 30, the

other end of which is broadened and shaped in the form of a shoe 31 adapted to bear against the peripheral surface of the fuse carrier and when the latter is rotated to proper position to makeelectrical contact with one of two contact pieces thereon. Both the clip 29 and the terminal 30 are secured to and supported from the quarter circle arc-shaped block 32 of porcelain or other suitable insulating material by screws 37,- 38, said block 32 resting at its opposite ends upon shoulders 33, 34 and being secured to said shoulders by screws 35. Between the ,shoulders the block 32 -bridges a recess or pocket 36 into which the terminal 30 depends. Inside of the casing the terminal' cable 23 leads to similar parts, the description of which need not be here repeated and to which the reference numerals heretofore mentioned also apply.

Thefcasing is partially closed by ring 39 with interposed gasket 40 and held in place by four screws 4l.

42 is a. cover fitting closely in the central opening of ring 39 and having a flange depending about an upwardly projecting neoeie flange on said ring 39; an interposed gasket 43 of cork or other suitable material insures a tight joint and yields sufficiently to permit themaking of a bayonet joint connection between the cover and the ring 39 about to be described. Notches 44, 44, (Fig. 4) at opposite sides of the central opening through ring 39 admit of the passage of lugs 45, 45 o n the lower edge of the cover 42 until such lugs clear the lower edge of the ring 39, whereupon the cover may be rotated to carry the lugs 45 out of register with the notches 44 into locking engagement with the under edge of the ring 39, the parts described thus constituting a bayonet joint. rllhe cover is preferably of cast metal hollowed with a depending stud adapted to fit into a central opening in the upper end of a fuse carrier 46, thus centering the latter With relation tothe cover. A suitable cement 47 filled intothe cover about the upper end of the fuse carrier 46 in a plastic state thereafter hardens and securely fastens the fuse carrier to the cover.

The fuse carrier 46 is preferably of porcelain but may be of other suitable insulating material. On opposite sides of its lower end, it hasyvertical grooves or channels 48 enlarged at their upper ends to receive contacts and other parts about to be described. Oneof these contacts, illustrated in detail in Fig. 8, consists of a plate 49 fitting against and held to' an over-hanging horizontal surface of the fuse carrier by means of screwbolts 50 and 5l passing through openings in said plate 49; a leg 52 of plate 49 has a rounded o uter surface adapted to engage and make electrical contact with the shoe 31 of the terminal 30 when the cover and the -fuse carrier have been rotated into position to bring these parts into engagement. A second leg 53 of plate 49 bears against an upright surface of the carrier 46 and has an opening 54 traversed by a bolt 55 the head of which is secured in a recess in the fuse carrier by a filling of suitable cement adapted to be applied in a plastic state and to thereafter harden. A spring 56 fastened to the underside of plate 4.9 also has an opening traversed by the bolt 55, a knurled nut 57 making screw-threaded engagement with the bolt on the outer side ofspring 56. This arrangement of .parts is duplicated on opposite sides of the fuse carrier and the descrippart of the link extending across the lower endof saidcarrier.

Two suitable forms of links or fuses for use in this device are that shown in Figs. 1, 5 and 9, and that shown in Figs. 10, 1l and 12. The construction of the former is as follows :-At `opposite ends it has notched copper terminals GO toeach of Which there is riveted and soldered a copper wire section G1 each of which is in turn riveted and soldered to a short flat strip section 62, preferably of zinc. These strips 62 are slightly tapered at their opposing ends which are positioned to terminate a predetermined distance apart and are connected by a narrower metal strip 63, preferably of Zinc, overlapping the strips 62, 62, and joined thereto by solder adapted to melt at a suitably low temperature. The Zinc strips G2, (32 as thus.

connected by narrower Zinc strip 63 constitute in effect an ordinar)T centrally notched Hat fuse strip or link. As most clearly illustrated in Fig. 1 such fuse link is bent in U-shape around the fuse carrier 46 with the narrow zinc strip 63 and parts of the strips (S2. (52, extending across the lower horizontal end of said carrier and the remaining portions of the link extending upward in the channels 4S, 48, at opposite sides of the fuse carrier, the notched terminals G0, (i0, each engaging its corresponding screw-bolt between the leg 5l and the spring 56 and being tightly gripped between such parts vby the tightening of the knurled nut 57. In case of excessive current traversing the fuse the temperature produced is such as to melt the solder connecting the strip G3 to the strips (S2, (32, permitting said'strip (53 to drop to the bottom of the casing 20, thereby opening the circuit. But in case of greatly excessivev current, such temperature might be instantly developed as not only to melt the solder joining the strip (33 to the strips 62, G2, but also melt the strip (53.

The object of the before described construction of fuse link is to overcome difficulty experienced when using an ordinary notched link of zinc or other similar metal, that of excessive temperature rise in the oil which might ultimately change the characteristies of the oil. This diliiculty might also be overcome by the use of a simple Hat link of Figs. 10-12, when made up in the following manner z-Two copper or bronze terminal strips 70, are notched for engagement with the two bolts 55, previously mentioned, and joined by fusible connecting strip 71, the overlapping ends of the strips 70 and 71 being riveted and soldered together.l Strip '71 is of some suitable low melting alloy, notched at its middle in the well-known manner for the purpose of giving the proper overload characteristics. The outer ends of terminals of this link being of bronze or copper and having a relatively lower resistance. are not heated excessively by the passage of the current through them, while the connecting strip 71, being of short length and low melting point, does not reach a very high temperature; it follows then that the total temperature rise in the oil is thus kept at a reasonably low figure. The

outer ends of the strips 70, 70, are bent as shown in Fig. 11, whereby the forcing of these bent ends to a straight position as' illustrated in dotted lines in said Fig. 1 1 and their engagement with the bolts 55 between the plates and the springs 5G places said strips 7() under a tension tending to cause the lol-fer ends thereof to spring apart or separate. In operation when an overload softens the fusible strip 71 at its notch, the strips 70, 70 spring apart as illustrated in Fig. 12 quickly separating the severed ends of the strip 7l, the action resembling that of a quick break switch submerged in oil and eliminating or minimizing any possible formation of an arc upon the opening of the fuse.

v The casing is filled with some suitable oil such as paraiiin or mineral oil, preferably to approximately the level, indicated by the line marked ()il level in Figs. 1 and 3, the action of such oil in preventing or suppressing the formation of an arc upon the blowing of the fuse being well-known. As has already been suggested, when the cover and the fuse carrier are insertedin the casing in such position as to pass the lugs 45 on the cover through the notches 44, the contacts 52, 52, on the fuse carrier stand in a line approximately transverse to the line of the terminal shoes 81, 31 and hence out of Contact with the latter; and to bring these parts into engagement or electrical contact the cover must be rotated through an arc of a i )roximatelv 90o which serves to carr the lugs 45 out of register with the notches 4-1 and hence into locking engagement with the under edge of the depending flange around the central opening through the ring 39. This insures locking of the cover in place before the electric circuit is established through the fuse link and its connections mounted on the fuse carrier 46. The action is reversed upon the removal of the cover 12 and the fuse carrier 4G, and if at the time of such removal the fuse link has not been disrupted and the, circuit is complete therethrough, the opening of the circuit will take place between the contacts 52 and the terminal shoes 3l both of which are at the time submerged in oil; consequently there will be no material arcing.V

To relieve possible excessive pressure within the casing due to theformation of vapor when the fuse acts under excessive overcharge of current, a relief valve is provided. As shownA it consists of a tube 75 threaded into an opening in the ring 39 and closed at its outer end by a plug 7 6. A stem 7 7 working through an opening in said plug carries at its outer end a cap 78 and at its inner end a piston 7). In the normal position, the piston closes vent openings S0 through the side of tube 75 and cap 7 8 tits down over the outer end of the tube, ex-

&

cessive pressure Awithin the casing forces the piston outward and opens the vents for the escape of gas or vapors. The cap 7 8 lsheld in its lifted position by the'friction of the piston, thus serving as an indicator showing that the fuse has operated.

. What ll claim is:

1. The combination of a receptacle orcasing containing a suitable arc suppressing liquid; circuit terminals within said receptacle; a cover and fuse-carrier for closing the receptacle; locking means for securing the cover in its closed position; contacts on the fuse-carrier adapted to engage the terminals in the receptacle respectively, said contacts and terminals being so relatively arranged as to be capable of such engagement only while the cover is locked closed by said locking means; and a fuse-link connected between said contacts on the fuse carrier.

2. The combination of a receptacle or casing containing a suitable arcv suppressing liquid; circuit terminals within said receptacle; a cover and fuse carrier for closing the receptacle; interlocking means on the cover and receptacle adapted to be engaged to secure the cover in place; contacts on said fuse-carrier adapted to be engaged with the terminals respectivelyY only by relative movement of the cover bringing the interlocking means into engagement in advance of the engagement of the contacts g, and a fuse-link connected between'said contacts on the fuse-carrier.

3. The combination of a receptacle or casing containinga suitable arc suppressing liquid; circuit terminals within said receptacle; a cover and fuse-carrier; a bayonetjoint connection between the receptacle and cover tor locking the latter closed; contacts positioned on said fuse-carrier to 'be er1- `gaged with the terminals respectively only by. the relatiye rotation of the coverand rel ceptacle servlng to interlock the parts of. the

bayonet-joint; and a fuse-link connected between said contacts on the fuse-carrier.

il. rThe combination of a receptacle or casing containing a suitable arc suppressing liquid; a cover for closing the top ot the re ceptacle said cover havin a carrier depending into the receptacle; interlocking means on the cover and receptacle adapted to be brought into engagement by relative rotation thereof; circuit terminals within the receptacle; contacts on opposite sides of the carrier adapted to be engaged with the terminals by said relative rotation which engages the interlocking means; and a fuse link bending around the lower end of said carrier and connecting between said contacts.

5. In an electric fuse, the combination of a fuse-link support, a fuse-link secured at two separated points to said support, said link at one or both of said points of anchorage being normally bent butin being secured to the support-caused to assume a more straightened position, thereby creating in the link a tension adapted upon rupture of the link to relatively move away from each other. theV terminals formed by said rupture.

6. In an electric Jfuse,tl1e combination of a fuse-link support, a` fuse-link secured at its ends to said support in an approximate U-shape, said link at one or both of its ends being normally bent but caused to assume a more straightened position in being secured to the support, thereby creating in the link itself a tension adapted upon rupture of the link .to relatively Amove away from each other the terminals formed by said rupture.

In testimony whereof l have signed this specification in the presence of two subscribing witnesses.

ROUES lV. DUWNES. Witnesses G. W'. STEERE, K. ltl. GREENE.

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