US1014098A - Thermal cut-out. - Google Patents

Description

J, SACHS.

THERMAL GUT-OUT.

APPLICATION FILED MAYfi, 1908.

1 1 4;, 098 Patented Jan. 9, 1912.

2 SHEETSSHEET 2.

A zM/A UNITED STATES PTENT OFFICE JOSEPH SACHS, OF HARTFORD, CONNECTICUT, ASSIGNOR. To THE SACHS COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OF CONNECTICUT.

THERMAL GUT-OUT.

, cut, have invented certain new and useful Improvements in Thermal Cut- Outs, of which the following is a full, clear, and exact description.

My invention relates to improvements in thermal cut-outs for electric circuits.

,Fuses have been described in which a strip was surrounded by a thin layer of material applied directly to the surface of the strip in the form of a paste and hardened, and then secured in a tubular casing provided with proper terminals electrically connected to the fuse strip. In other instances, an immediately surrounding loose material has been held to the strip by a tubular sheath or interior casing surrounded in turn by an external casing having terminals to which the strip was electrically connected. The constructions referred to in this paragraph are described in a patent granted to me October 24th, 1899, No. (335,395.

In order to more advantageously use a loose filling in the inner tubes or casings referred to in the last paragraph, it has been suggested that that tube be provided with end closures so as to produce a. cartridge, the casing and closures of which would keep the loose filling about the strip. This cartridge construction placed Within a second casing is described and claimed in my Patent No. 737,282, granted August 25, 1903.

Fuses have also been patented in which the strip was jacketed with a Woven asbestos tube so that the strip and tube were as a combined structure inserted in a box or casing. the whole constituting an inclosed fuse with a porous jacket as distinguished from a fuse surrounded by a loose porous material, inclosed in a non-porous sheath. This asbestos sleeve structure is described in patent to McCullOch, No. 550,638. In all these devices employing inner tubes, with or Without closures for such inner tubes, the expense of the construction has been a great objection, furthermore a large portion of the space within the outer casing has not been utilized. Moreover, there has been no satisfactory means for ascertaining what the Specification of Letters Patent.

Application filed May 5, 1908.

Patented Jan. 9, 1912.

Serial NO. 430,976.

condition Of the fuse strip may be by an inspection from without the outer Casing. In the structures where an adhering substance Was applied directly to the fuse strip it was a mere coating and not a filling or provided with chambers or interstices permitting the ready dispersion of the gases and metal of the fuse When molten, and did not fill the external casing. In the asbestos sleeve construction there was no filling, properly speaking, but simply a sleeve which occupied but a small portion of an inclosing casing, the gases discharging into the air space surrounding the sleeve. On account of the expense and little advantage of such devices the inclosed fuses of commerce are now and for a long time have been constructed without employing an inner cartridge, and Without employing any inner sheath for holding the filling about the strip and Without hav ing the strip either jacketed orcoated, but

so that the outer casing holds a loose filling.

material about the strip and so as to be ready for use without doing more than to make connection with line terminals. That is, the inclosed fuses of commerce have been constructed with a fusible conductor surrounded by a loose insulating filling material held'abontsaid conductor by a tubular casing, the end openings of which were closed by conducting ferrules or end caps, which in themselves acted as the external contacts or from which the Contact blades projected. This combination of parts formed a composite self-containedcartridge structure, and was manufactured, sold and used as a whole to be used Without any additional casing and could only be replaced by an entirely new and similarly complete device whenever the fuse strip Was blown or ruptured by an excess of current. These cartridges have been inclosed in fuse plugs, but except in fuse plugs they have not been introduced to any extent into commercial use in connection with other external casings. As the tubular casing, ferrules and external contacts form the major portion of the mate rial cost of such incloscd fuses or cart-ridges, particularly in the larger sizes, the replacing of such blown or ruptured inclosed fuses of this type is necessarily expensive. As such complete structures are manufactured for a definite carrying capacity and cannot be readily changed by she user or seller, itis necessa y that he 8&11/ a large variety of the p *seno form of complete inclosed fuses of drier ens ampere capacities for a certain size block he desired to prepared to i ery the current carrying capacity of his inciosed fuse o out apofanee. This consequently nccessit Les a expenditure for siflo'clr iiiciosed fuses, which. could be eliminated if a cheap refill or reioad were provided the tubular casing, ferrules and external consaets were properly constructed, so llllQV could he used repeatedly if the disruptedsirip its arc-dissipatiag envirouinen'fi which held around it within. om tuhnia asing could. be easily and iyirenewe One oftheobjecos of my invention is to satisfactorily aeooroplsi. this resuit, and to that end 1' provide iniegrally combined reloa or reliil onsistin of: the fuse stri'o surrounded by s oohei g arc-dissi- Dating filiing substance so that these two elements or parts are in: themselves cora unit and will. hold Wiill addinionsl means, also suitable easing, hex, sube, or other e. .ernal gorotecfior inclosing struc l which eu oe refills or reioads can be ream i which they suhstaniaily fill, provided whereby the tern strip of the reload or quickly and securely eonneeiv nai. contacts ehe ins i casing see 'ly closed preferably 1y the iisuring she proper e the fuse sizrip hetweei'i t by the operation of casing so that i memberineu pressures d lisruption 01.. structure ine ass? vsingthe ably casing closu e um. Lu with the p and. replaceable r e: annals are whole we now in use casjacketed 41151.2) 4. one 32 .cwisno the reloed or refill and in the preferred form entirely surround the indicating means bodying n y invention. Fig. 2 shows in plan a reload or refill with the terminals of she fuse strip extending at its ends. This reload has located upon it an indicator form" ing a composite pare thereof. Fig. 3 shows a partial view with the casing in longitudinal section on the line g -g Fig. 4., an end view of the fuse of Fig. 1, the plate being removed. Fig. 5 is a sec iion i'z-alren through Fig. 1 at the line 2e. F 6 shows an end view of the refill shown in 2. 7 shows in section a fuse plug embodying my invention. Figs. 8 and 9, 10 and 11 show reloads withnnodified forms of terminals at their ends and corresponding ca ing terminals. Figs. 12, 13 and 14 show a LilSG block embodying my invention, Fio'.

being a side elevation partly in section,

Fig. 13 a portion of the block with one of the covers removed, and Fig. 1 an end eleration.

Referring more particularly to the drawings, A is a casing, preferably tubular and constructed of fiber or other suitable insulating" material. 13-13 are counterpart metallic end caps or casing terminals fitting over the ends of said. casing and held thereto by suit-able fastening devices, the fastening device shown consisting of a screw C en aging a bayonet slot 1) in each of the end The screws G preferably engage with nuts or groniets (,Z sunken in the tubular easing so e0 furnish a strong screwihread, and the ends of the screws may be headed eveon the inside of the casing so that they mot h entirely removed therefrom. .ihe screws engaging with fihebeyw ei; slois constitute preferred form for securing the caps in position.

suitable means, however, may be employed for accomplishi this purpose. When end closures are used one of them at least should be removable. in the large sized fuses the end. cans are nrovided with contactblades "*l; ies B are omitted as consliaiul'e both end Any other mg E, through which evidences of the condition of the refill can be detected.

Means are provided for securing the terminals of the fusible strip in electrical engagement with the end caps, the preferred form being that of Figs. .1-4 and consistin" of a clamping device consisting of 9. sp it plug having two parts F-F and a nut G. The parts F -F each have a flaring end HI-I' which engages a conical bearing surface I on the inside of the cap. The

split plug has a hole through it concentric with the end of the fuse strip terminal.

\Vhen the refill is secured. in place the round terminals project into the holes in the clamps, and the nuts are screwed down so as to draw the split plug members FF into close clamping engagement with the terminals, thus securing an excellent electrical continuity between the fuse terminals and the end caps and the contact blades B attached thereto if such contact blades are used. The caps when clamped to the fusible wconductor terminals are by such clamping fixed in position relatively to one another and to the casing. The nuts G are screwed on by a right hand movement and the caps are turned by a movement in the same direction to seat the shanks of the screws C against the innermost ends of the bayonet slots. This seating of the screws C and the screwing of the nuts G can thus be done by the same movement or operation.

The refill or reload consists of a fusible conductor J which, as shown, is connected between terminals or connections K-K of copper or other metal harder and less fusible than the fusible conductor J. These terminals or connections are shown in Figs. 1, 2, 3, 4t and 6 as round wires, riveted, soldered or otherwise connected to the ends of the fusible conductor, and in Figs. 9, 10 and 11 as flcxibk strips of copper or the like. The

fuse strip and the inner ends of the terminals are surrounded by a cohering jacket L, which consists of insulating material. I prefer to use ,for this purpose granular earthy substances of the calcium group, which are combined by means of suitable binders toproducc an integral cellular-multichambered spongy or porous mass, which 7 mass 15 molded, compressed or otherwise formed and held around and in contact with thc'fusc strip so as to form therewith the jacketed strip or reload. A suitable way of making this cellular jacket is to combine coarsely ground set plastcrof-paris with a solution of silicate of soda,'which forms therewith a pasty mass and at the right consistency can be cast or molded around the strip. It may also be formed by holding the ground material about the fusible conductor in 'a mold and pouring silicate of soda through it while thus held. The surpreferably provided with a window or open-,

plus silicate of soda is permitted to drain off leaving interstices between the granules or particles of the plastcr-of-paris which are held together by the binding and chcni'r cal action of the silicate of soda, forming a. cohcring cellular jackct adhering to the fuse strip so as to be integral with the fuse strip. Although a suitable jacket may be made in this way, various faitures of my invention may be embodied without the use of ajacket which adheres to the strip. I therefore do not limit myself to such an adhering or integral jacket or the stated chemical elements, since they are not essential to form the cellular structure of my reload jacket.

,It will be noted that the jacket L is molded so as to entirely inclose and surround the fuse strip J and also a small portion of the inner ends of the terminals or connections KK between which the fuse strip J is connected. It is al o preferably of such size as to nearly fill the casing, but not to bind therein when being inserted or removed.

Although I have shown terminals lC-K of metal harder than the fuse strip and not integral therewith, this not of essence, since other well known forms of strip and terminals can be used.

In order that the condition of the reload may be apparent on the exterior of the jacket, and'if necessary on the exterior of the external casing surroimding the jacket or cohering filling, I provide indicating means which in Figs. 1, 2, 5 and 6 are shown as an indicating compound or connection M located and electrically connected between the ends of conductors N--N which at their outer ends are electrically jointed or connected to the terminals K-K. This indicating connection M is composed of a conducting material such as graphite with which has been incorporated an easily ignitible or heat affected material, such as gun powder, or picric acid. The combined substances are put into plastic or fluid condition, and in this state the compound is placed in position between the ends of the conductois N--N. These ends are previously hooked over from the under side of a perforated sticker or label (l, so that the secured against turning by being slightly I embedded in the jacket, or by solder, or I both, and extends beyond the periphery of the refilkso as to engage a notch or recess l?" in one end of the tubular casing. This arm or projection has a fixed or definite sition relatively to the indicator c )Ollilfl.

The casing is provided with a window or aperture E, which is at a proper distance w from the notch P so that the arm or projection P when within the notch P will cause the indicator compound to be in the proper position relatively to the window or aperture.

The jacket L after it is dried is preferably coated with one or more coats of as phaltum or similar heat-resisting varnish to give it a finish and increase its coherency. This should preferably be applied after the indicator conductors have been connected to the fuseterminals. The inner end surface of the caps is covered with a felted asbestos washer ll,j held in place by the flaring upset portion that forms the conical recess T. This washer covers apertures or vents T in the casing terminals.

In using my reload-able inclosed fuse, it is necessary simply to take the reload consisting of the combined strip and jacket, and insert it into the tubular casing througlr the opening at either end, one cap only be- .ing removed. After being positioned therein, the removed cap is replaced and having a screw-threaded opening engagin turned so as to be secured by the bayonet joint and the nuts G screwed down so as to clamp the fuse terminals it. to the It is desirable that the reload be so inserted that the indicating connection be removed from, though in proximity to, the aperture in the casing, and it will be noted that it is not possible to insert the reload otherwise on account of the registration p'" l? fitting in a recess 1 in the casing.

v The indicator compound is therefore entirely surrounded.

45 by the casing and there is, therefore, no one posed conducting element at the opening so that it is not possible to have any Flash or are at this opening, due to the rupture of any conducting element at that point, as

would be the case if a current carrying conductor were located directly beneath the hole or aperture in the casing. An exposed flash atthe opening would be a source of danger, since it liable to ignite any explosive gases \vl Ich may be present, or any easily ignitablc material which may be at" hand, and the presence of an exposedccnductor at the opening is undesirable in that it enables an GlBCdllQ connection to be made at that point.

' in operation, an excess of current go st through the fusible strip will 3' ing it to rupture, and the prodir disrupted strip will be dissipated I 1 v the interstices of the cellular or on up the arc. As soon as the use been thus ruptured, the current 7 then pass through the indicating con 3B, which. is connected in shunt around. strip. This connection being of Very ni h resistance, normally does not carry appreciable current. "W hen heated by the passage of current after the fuse strip is, blown, the indicating connection will be ignited or otherwise affected, so that the products of such heating, ignition or other change, will be of a nature to discolor the surface of the label in proximity thereto. This discoloration will be visible from the an exterior of the external casing through the aperture, and thereby the condition of the reload will be seen. The folded flap 6'. serves to direct'these products toward the aperture E soas to insure that the portion of the jacket beneath the aperture shall be subjected to them. v

Fig. 8 shows the refill with another form f terminal and indicating device, and. also other means of fastening the cap upon the as casing and electricallyconnecting the-fuse strip thereto. In this form the fuse strip is provided with screw-threaded terminals Q; over eachpt which ispassed a cap It,

said terminal screw-threads. The cscrewed on to a terminal Q, and a setis then screwed upon the screw-tin... portion Qholding the together. a contact blade 8 free from the cap may made integral with this nut, tl e thread i ing sutiiciently fine so the blades at the ends can be placed in the same plane. cap is secured to the casing by a screw passing directly through a hole in the cap. An indicating connection M l8QiE'lC.. connected by conductors N-l*l as in Fig and acting in the same manner, is attached to and earricd'by the jacket of the refill and its strip. Another means of securing the e it to the casingand electrically COHH'EL the use strip thereto is shown in ll, 10 and 11. Tn this construction the fuse strip terminal of thin :tleiriblt metal, preferably copper. It is bentlI" so as to come in direct contact with the terior surface of the casing- A. The nal of the fuse strip is provided with. a slot a which is slipped aroundthe shank of the screw V. The cap B with its bayonetjoinbW is then slipped on and turned in .iil

place and the screw set so as to hold the p in place and clamp it against the unnal U.

in. 7 shows my invention in a fuse plug. in this constru cn'ibod o ticn, 1. the refill, consisting of a j: 4 strip at h as shown in Fig. but horter and. w out an indicator, this latter feature not beed by a cohering integral cellular nally manifesting the condition of the fusible conductor through the aperture, and means for positioning the reload in the casing so that the indicator is entirely inclosed and completely surrounded by the casing and out of alinenient with said aperture.

9. In an inclosed fuse, the combination of a tubular casing of insulating material, an indicator hole in said casing, end closures and circuit. connecting contacts at the end of the casing, a fusible conductor surroundfilling material forming together a removable reload, a shunt circuit indicator attached to and forming a part of said reload, said indicater being upon the outer surface of the filling material, means 'coacting with the end closures and the terminals of the fusible conductor projecting from the ends of the reload for detachably holding the reload within the casing, and electrically connecting the fusible conductor to the contacts,

and registration means for locating the reload in the casing so that the shunt indider of cellular structure having a multitude of interstices for receiving the products of the fuse strip When disrupted, a fusible conductor Within the filling with terminals extending beyond the ends of the cylinder, and

an indicator mounted upon said cylinder;-

11. A filling for inclosed fuses composed of granular non-conducting materlal, in combination with a non-conducting blnding agent holding the same together in the form. v

of a cohering cellular mass.

JUSEPH SACHS.

W'itnesses: g 7

LILLIAN S. James, H. B, Baownntn

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