US2074400A - Dual fuse with indicator - Google Patents

Description

March 23,1937. L, A KAQFFMAN 2,074,400

DUAL FUSE WITH INDIJATOR Filed April 24, 1935 Patented Mar.` `1937 -V `lcarrito srrii'rlts 2,074,400 DUAL Fusi: wim mnrca'ron Leroy A. Kauffman, Washington, D. C., assignor indicating lFuse Manufacturing Corporation,

Washington, D. C., a corporation oi Delaware Application April 24,1935, serial No. v118,040

' y' s claims. (ci. zoo-121) ing parts are designated lby similar reference The present invention `relates 'to circuit breakers for -the protection ci electrical circuits (employing a fusible element) Whichbecomes blown or ruptured'when a short circuit or overload occurs in ther electrical circuit lhaving amongst its' principal objects the provision of an automatically controlled switch connected in sey ries withthe-vfusible element which will function beforethe fusible element when a 'slight overload occurs to break the electrical circuit and continue to intermittently and momentarily reestablish the current should such overload continue over a period of time, thereby maintaining the circuit in substantially continuously broken condition and which will again close'the circuit'when -such overload is removed thereby increasing the ufe of the fusible element.

A further object of the invention. is to provide afuse with two thermal control circuit breakers ci different amperage, the circuit breaker having the lower value being adaptedl,to automatically open and close the electrical-circuit and the circuit breaker having the greater` value adapted to permanently open the electrical circuit when blown or ruptured'.

A still further object ofthe invention is lto provide a fuse comprising two' thermal control cir--` cuit breakers connected in' series and an indicator connected in parallel therewith, whereby when either circuit breaker is opened, said indicator will announce or signal thebroken condition of the electrical circuit to which the fuse 'is l applied., 1 A

" Another object ot the invention is to provide a fuse comprising a unitary structure having a plurality of circuit breakers housed therein and connected in series with the contact terminals of the fuse and an indicator connected to the terminals of the fuses, but arranged in parallely Withthe circuit breakers for indicating the ruptured condition of either circuit breaker,

Other objects of the inventionwill be in part obvious and in par'trpointed out hereinafter.

In order that the invention and its mode of op- 'e 55 panyingA drawing, wherein like and correspond through l K characters throughout the several views, I have Y herein shown a fuse of the plug type'consisting oi' a casing molded from a suitable insulating material to provide an upper section I and a lower or detachable section l The upper section?! has attached thereto a threaded contact shell 3 capable of being tted within a standard scket of the ordinary cut-out block and detachably fitted within this shell 3 is the lower section 2. q The upper section l has formed therein a centrai recess in which is arranged an indicator s,

herein shown as a miniature glow lamp 4. Terminal 5 of this lamp is connected to the shell 3 through a resistor 6. The resistor as herein shown is formed from a plastic composition containing carbon and glycerine and is positioned.

Within a recess formed within the section l of the gcasing as is better illustrated in Figure l'. The -wother terminal i' of the lamp 4 is attached .to ab tion i ofthe casing.

rivet 8 secured Vwithin the lower end of the sec- The lower section 2 of the casing has formed l thereinran annular recess so that when the saine is connected to theupper section l, a fuse compertinent 9 is formed. A rivet iii forming a contact terminal oi the fuse is mounted within the lowersection of the casing. The fuse link il is carried by a holder l2 and when placed within the ruse compartments, one end of this link il contacts the rivets B and it; thereby completing a connection between the terminal i of the lamp indicator and the contact rivet iii.

The automatically controlledxcircuit breaker comprises la switch having a movable blade i3 and a stationary contact it. To provide this stationarycontact, i' form a metallic copper strip in the shape as is better shown in Figure 3 in orderthat one end i5. may project within the fuse, compartment 9 and have contact with one end of the fuse link ii whereas, -its opposite end projects within the chamber i6 and forms the riveted thereto asat l1, an arm l8- made from a suitable bimetallic material and the lower end oi this arm i8 `is connected with and supported Vby ,an extension i9 which latter extends through `the fusefcasing and has Contact with the upper end of the shell, 3. The upper end of the chamcontact it. The upper end of the blade i3 has'.A

ber I8 is closed by means of a plug 2,0a'nd the A lower face ofy this plug is provided with a recess y l2l in which mayloscillate and pivot the upper connected ends Yil' of the arm 18 and switch blade I3. The outer face 22 of this plug!!! may have suitable markings thereon to deste the ratings in amperes or the fuse whereas. the outer face 23 of the fuse casing may have the required markings such as thetradei-M k, nome f menufacturer and voltage oi the fuse.

2t are formed with the outer edge of the section i of the fuse casing thereby providing a ha grip for turning the fuse, into and out of the cut=out base socket to which the fuse is to be applied.

lo From the foregoing, it is obvious vthat the clisg-a h@ me link H Md the cuit breaker comp circuit breaker comprising e switch blade i8 are connected in series with the termils i@ 25 preciabie diminution oi their theo-nenible properties and yet form a good conductor predetermining the pebie maximum current how, but is adapted to automatically respond to the heat generated by excess temperatures by fien- 30 ing to a circuit :its ition. arm i8 having e. thickness and width adapg it to carry or conduct a ww perego, but an amperage of a lower value than that oi the maximum value of the fuse ii will, when a slight 35 overload occurs in the electrical circuit to which vit is applied by the 4heat generated, des the arm i8 so as to cause it to'wilr-vr the blade i3 i'rom the contact it before the fuse link ii becomes blown or rub and thereby break the v 4o circuit. As the arm it cools, it will automatically return to' its normal position to again cause the blade i3 to engage the contact it for ablishl ing the circuit, but should the overload continue, the arm i8 will maintainthe circuit in subs 45 tially a continuous broken condition until the overload is removed. `However, .should the over load or short circuit ca an '..r c. .s to a .value greaterthan the the fuse link ii, the latter will :f 50 to the heat so generated and permanently open the circuit until such time as a new fuse link is substituted therefor.

4 The plug 2d when piacedin position will exert 'a pressure upon the arm lo and blade it so.` as 55 to flex the same in their normal tions as is shownin full lines in 1li dfwhereby the blade i3 will be retained in contact with terminal i4. en the hat is generated by the overload occurring in thefclectrlcal circuit, the

shown in dotted lines in Figure i thereby drawing the blade it out oi engagement with the contact it. The upper connectedends il or-the arm it and blade iB' are fulorumed within the recess 2l oi the plugl@ in ,auch a manner as to permit a slight variation inftheiriulcnnn point and therebyrcause-ithe blade to snap out o! arm I8 will contract or e the position as .of said compartment,

ruse plug, so that'st overloads that occur in `an electrical circuit may be taken care oi with- `out rupturing the fusible elementn but in the' event a short circuit or exve overload occurs, the fuse link will function inthe usual manner and the lamp 4 will signal or indicate the opened condition of either circuit breaker.

Maniftly, the construction herein shown is capable of considerable modication and such modifications as come' within the scope of my cl, I consider within the spirit ci my inven tion.

I claim:

1. A fuse comprising a body. a center contact. a shell constituting a side contact. a thermo-responsive switch housed in said body and having a stationary section and a movable section, a u'se link connecting the stationary section with the center contact, a thermos-responsive strip extending longitudinally of the movable section and having one end secured to an end of the movable section and being normally bowed in one direction to support the movable section in position to engage the stationary section, s for electrically connect the other end of the thermo-responsive strip with said shell. the strip when bowed in an opposite direction in response to change in thermal conditions supmrting the movable section out of contact with the stationary section, a pocket being formed in said body and open at one end, a glow lamp indicator in said pocket visible through the openend thereof, a resistor connected in series with said lamp, and means for connecting said glow lampl and the resistor in series with the center contact and the side contact but in parallel with said thermoresponsive switch and the fuse link whereby the inoperative position ci' the thema-responsive switch or the fuse link may be visibly indicated.

2. A plug fuse comprising a casing having aplurality of compartments individually separated from one another and located within said casing. a fuse link arranged within one of said compartments, a thermo-responsive switch arranged within one of the other oi said compartments, a lamp indicator nged within the remaining one'of said compartments, a central contact secured to said casing, a screw shell contact secured to said casing, means arranged within said casing for connecting said theme-responsive switch and ruse element in series with said `central contact and said screw shell contact and l means arranged within said casing for electrically connecting sald lp indicator with said central contact and said screw shell contact wherebythe inoperative position of either said fuse linkv or said thermo-responsive switch may be visibly indicated.

3.a fuse unit comp a casing, a pairof spaced contact terminals carried by said casing, said casing having an opened end compartment formed therein dening intercommunicating inner and outer chamber, a circuit breaker 'arrangedwithinsaid o .tf-:Mt- -fand including a stationary contact in the inner 'and electrically connected to one contact terminal and extending into the outer chamber and a movable contact in the 'outer chamber electrically connected with the other contact terminal, a plug'secured within and closing the'opened vend Seid plus ensasins the moveableccntact of said circuit breaker .for normally@ holding the same in engagement with the stationary contact.

v i l 4. A plug fuse comprising a casing, a central contact terminal, a screw shell terminal, said casing having an opened end compartment formed therein, a thermo-responsive switch arranged within said compartment and being electrically connected to said central contact terminal and said screw shell contact terminal, said thermoresponsive switch comprising a xed blade and a movable blade, a plug for closing the opened end of said compartment and engaging said movable blade of said thermo-responsive switch for normally retaining the movable blade in contact with the xed blade of said thermo-responsive switch and said plug having a recess formed therein providing avariable fulcrum point for the movable blade oi said thermo-responsive switch.

5. A plug fuse comprising a casing. a central contact terminal, a screw shell contact terminal, a thermo-responsive switch arranged within said casing, saidthermo-responsive switch comprising a xed blade and a movable blade, means for connecting an end of said xed blade to said central contact, an abutment having a seat shiftably receiving the other end of saidA movable blade, a bimetallic arm for normally retaining said movable blade incontact with said xed blade having one end ilxedly connected to said movable blade and holding the said end of the movable blade in the seat of said abutment and means for connecting the opposite end of said arm to said screw shell contact terminal. 6. A plug fuse comprising a body having upper and lower sections, a shell connecting said sections and constituting a side terminaba c nter terminal extending through the lower tion axially thereof, the lower section being formed with a fuse chamber surrounding the center terminal and Vopen at its'upper end, the upper section being formed with an axially extendingl pocket open at its upper end and with a i. longitudinally extending switch chamber spaced cator in said pocket having terminals connected with the resistor and the stud terminal; a thermoresponsive switch havingfa stationary member in the fuse chamber engagingthe fuse and a movable member in the switch chamber, a bimetallic member holding the movable member in contact with the stationary member and connected to the shell, and a plug closing the switch chamber and constituting a fulcrum for the movable member.

7. A plug fuse comprising a body having upper and lower sections, a shell connecting said sections and constituting an external side terminal, the upper section being formed with a pocket, a contact stud secured through the bottom of said pocket, a center terminal carried by the .'.Jwer section under said stud, a fuse having one end clamped between the stud and center terminal, a resistor between the shell and pocket, a glow'lamp in said pocket having terminals connected with the resistor and the contact stud,

' said upper section being also formed with a switch chamber having a reduced passage leading from its lower end and a side passage, a plug closing the outer end of the switch chamber, a stationary switch member bearing against the under face of ing of a bimetallic strip extending longitudinally in the switch chamberwith its upper end bearing against said plug and its lower end provided with a foot extending through the side passage yand secured to said shell, and an arm extending section and engaging said fuse link, a side con' tact, the upper section being. formed with an open pocket-and with a. switch chamber, a'plug closing the switch chamber, a glow lamp in said pocket, a resistor in series with said lamp, the resistor and lamp being in series vwith the center contact,

fuse link and the side contact, a, stationary contact resting upon said fuse link between the upper and lower sections and having an arm extending Iinto the lower endportion of the switch chamber, a bowed bimetallic strip in the switch chamber v having its lower end connected to the side contact and its upper end in shiftable engagement with said plug, and an arm Aextending downwardly from the upper portion of the bimetallic strip with its lower portion normally in engagement with the arm of the stationary contact.

LEROY A. KAUFFMAN.

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