US2476236A - Combined fuse bank and alarm switch - Google Patents

Description

July 12,1949.

A. BUCKLEY COMBINED FUSE BANK AND ALARM SWITCH 3 Sheets-Sheet 1 Filed Jan. 8, 1948 July 12, 1949. A. H. BUCKLEY COMBINED FUSE BANK AND ALARM SWITCH 5 Sheets-Sheet 2 Filed Jan. 8, 1948 7' git/{514a Z9. (1y. 5M W July 12, 1949. A. H. BUCKLEY COMBINED FUSE BANK AND ALARM SWITCH 3 Sheets-Sheet 3 Filed Jan. 8, 1948 Patented July 12, 1949 COMBINED FUSE BANK AND ALARM SWITCH Arthur H. Buckley,

Chicago, 111., assignor to Reliable Electric Company, Chicago, 111., a corporation of Illinois Application January 8, 1948, Serial No. 1,207

Claims.

This invention relates to alarm systems, and more particularly to an alarm system for directing attention to the location of an open circuited fuse that is one of perhaps thousands of fuses in a central installation.

As is well known, the central office equipment in communication and other electrical systems includes a large number of separate electrical circuits, and each one of these circuits normally requires an overload protective device. These protective devices generally take the form of thermal fuses that contain current carrying fuse metal having a comparativel low temperature melting point. When more than a predetermined amount of current passes through the fuse metal, the temperature generated therein is sufficient to melt the metal and thus open the circuit before damage is done to other circuit components.

Where perhaps thousands of such fuses are closely arranged in what are called fuse banks, it is desirable to provide an alarm system for directing attention to the location of a particular open circuited fuse.

Accordingly, one object of the invention is to provide an alarm system having characteristics such that it can be relied upon to operate at all needed times, particularly at times that may be months or even years after the installation of the alarm system. Therefore, the invention contemplates features intended to obviate operational difliculties that sometimes occur with infrequently used mechanical and electrical apparatus.

Another object permits the use of precious metal electrical contacts in the switches used with the alarm system. Since the cost of such metal contacts would be prohibitive if a pair of such contacts were used with each individual circuit, the advantages thereof without the prohibitive costs are achieved through the use of a single pair of contacts with a plurality of separate circuits.

Still another object contemplates an alarm system for use with a large number of fuse banks, the indicator components of the system taking the form of a signal lamp associated with each one or two fuse banks, and an audio indicator associated with each larger group of fuse banks. With such indicators, an open circuited fuse in any one of the many fuse banks of the installation causes a buzzer or other suitable audio device to direct attention in the general direction of the alarm actuating, open circuited fuse. The signal lamp on the fuse bank containing the open circuited fuse then directs attention to that particular fuse bank. Since the fuses used are of 2 the plunger type such as shown in United States Patent No. 1,691,705 to Wallace L. Cook, the particular open circuited fuse in the indicated fuse bank is readily identifiable.

Other objects and advantages of the invention will become apparent as the description proceeds, reference being had to the accompanying drawings wherein one form of the invention is shown. It is to be understood that the description and drawings are illustrative only, and are not to be taken as limiting the invention except insofar as it is limited by the claims.

In the drawings,

Fig. l is a view in side elevation of a fuse bank which the present invention has been applied; Fig. 2 is a view in front elevation of the fuse bank;

Fig. 3 is a top view of the fuse bank;

Fig. 4 is a sectional view on line 4-4 of Fig. 1;

Fig. 5 is an enlarged fragmentary view of a portion of Fig. 4 showing certain mechanical components of the invention in alternative positions;

Fig. 6 is a view showing details of the switch mechanism connected in circuit with the indicaters to complete the circuit in response to an open circuited fuse;

Fig. '7 is a circuit diagram suitable for use with the invention;

Fig. 8 is a view in side elevation, partly in section, showing details of the plunger type thermal fuses used with the invention;

Fig. 9 is a fragmentary view in front elevation of a fuse bank showing certain details of the invention; and

Figs. 10 and 11 are views showing additional details of the switch mechanism of the invention.

Referring now to the drawings, a fuse bank of the type used with the invention is generally indicated at I5. Fuse bank l5 may consist of a vertically disposed structural member l6 that carries spaced brackets 11. A central sheet l8 of insulatin material is associated with brackets I1, and thus it is supported in a vertical plane by member l6.

Central sheet l8 carries a plurality of vertically spaced rear fuse holders 20 (Figs. 3 and 4) and a plurality of corresponding front fuse holders 2|. A fuse 22 is carried by each pair of corresponding front and rear fuse holders.

Thus it will be seen that each fuse bank l5 comprises in reality two subsidiary banks of fuses, the two banks being disposed symmetrically one on each side of central sheet 18. A fuse bank may contain any convenient number of vertically am ss metal, a spring 24 (Fig. 8) within the fuse body causes the plunger to eject to .thus provide a visual indication of fuse failure. Since plunger*23is ejected with some degree offorce under the influence of spring 24, the action of the moving plunger is used in connection with a mechanical switch, presently to be described, to cause operation of the present alarm system.

For convenience, the following description will concern itself with the fuse bank and associated instrumentalities lying on one side of central sheet {8, it being understood that the structure'on the other side is symmetrical therewith. Operation of the present alarm system depends upon a novel switch mechanism that is provided in conjunction with each vertical bankof fuses, the switch being such that it is actuated by any one-of the {uses of that bank. As mentioned, the switch is actuated through action of the moving plunger of an overloaded fuse.

The switch mechanism comprises elongated member 26 that extends in spacedrelation to the front ends of the fuses in a bank. lhe elongated member 26 falls or is forced to asecondor lower to rotate through a limited arc through action of a plunger 23 following a fuse overload. ne means for rotatably mounting member 26 takes the form of a Vertical rod 21. that has itsupper and lower ends bent to provide horizontabportions 28 and 29, respectively. 'I'heportions 28 and- 29 extend rearwardly of the front of the fuse bank and are suitably fastened to central sheet I8. Elongated member 26 has upper and lower horizontal lugs 30 and 31, respectively, -the lugs having holes therein through which the rod 21pxtends. Thus rod 21 forms an axis of rotation for elongated member 26, rotationot the member 26 through a limited arcof say'20 degrees occurring as a result of plunger action. g

The vertical portion of rod- 211 is somewhat longer than elongated member- 26 so'that the latter may move through a limited vertical --distance along the length of rod 21. ;As will later be seen, the member 26 is normally in a first or upper axial position on'rod 21, and thenupon member 7 rotation following fuse overload the member 26 failsor is forced to a-secondior lower position. When the member is-in its lowerposition, the switch associated with the-member becomes closed, as will presently be seen.

The axial movement of member 26 is permitted by a cam element 33 that-is positionedbetween the bottom of member 26 and the horizontalportion 29 of rod 21. As illustrated, cam'element 33 isintegral with the bottom of member 26, andit rests under the weight of member 26 on red portion 29. Element 33' is providedwith at least'one step in its cam surface so that the element supports member 26 in either oftwo vertical positions with respect to rod .portion 29. One vertical position is illustrated in Fig.;.6 wherein the edge 34 of cam element 33fis resting on portion 29. This position is the first or'upper position previously mentioned. The second or'ilowerposition is brought about throughrotatiorfof member .26,

the cam element 33"being alsofota'tedso'that'the 4 step therein passes portion 29 and permits the member 26 to fall to the second or lower position shown in Figs. 10 and 11. In this position the horizontal plate 35 of cam element 33 rests on the portion 29 of rod 21. Member 26 and cam element 33 constitute the actuating portions of the switch mechanism.

Referring-again to Figs 5,6, llland 1-1, the remaining portions of the switch mechanism will 'now be described. A fuse bank identifying number plate 38 is mounted at the bottom of central sheet IS. The number plate 38 carries a laterally extending bracket39 having on its upper surface a switch contactAD. The contact 40 desirably is madeofpalladium metal or other suitable precious metal having satisfactory characteristics for use as'a'switch Contact. Cam element 33 has a laterally extending portion 4| that carries on its bottom surface a switch-contact 42 made of similar precious metal material.

The switch contacts"40 -and 42'areso disposed with respect to each other that they are in a spaced apart relationship when the member 26 is in its first or upper position. However, upon rotation of member 26 in responseto'fuse action and the consequent movem'ent'of member 26 to its second or lower position, switch contact is brought to alignment with 'switchcon'tact lfl' "so that the two contacts enter into physical engagement, thus'closing thefsv'v'itch' ande s'tablishingthe circuit to the indicatorcompon'ents of the alarm system.

Referring to Fig's.'2' and e, anfimport'ant feature of the above described switch actuating mechanism resides in the use" of tensiond spring 45. The purpose ofspring li isftofprovidea force between elongatedhiember '26 and a stationary part of the fuse "bank, desirably the vertical rod 21' that 'forms'the support'and the axis of rotation for member-26. As shownfone end of the spring isan'chored at a point-46cm the top 'of member zsawaynom the-axis Iof rotation, while the other endof the"sp'r'ing .is anchored to a point 41'on' radar. "The point in is located'in a position on rod 21 so that-the spring ends are disposed in spacediradial planes when the member 26'is in its first or upper position. The angle between 'the radial planes passing through the spring ends -is roughly the angle throughwhic'h' member 26 rotates inpassing to its second or lower position. Thus the spring is biased to assist in rotating member '26. L'Spring 45 is fixed'in an extended condition so that a force of tension continually exists between the points 46 and 41.

Spring '45 cooperates in-several different ways in influencing the action of the switch mechanism. Firstly, when elongated member 26 is in its first or upperiposition (with .theswitch contacts out of engagement), the spring causesa pressure relationshipbetween camsurface 34' and the horizontal portion29 of rod 21. This ,pressure engagement tends tomaintain the member 26 in itsfirst' "angular position .againstaccidental or unwanted rotation 'such as might .occur through vibrations or other causes. Secondly, due to the biased manner 'in"which.spring'f4,5 is mounted, the "spring tension ."augmentsfthe "force applied to member 26 by -a projecting plunger 23, so as to insure that"member' 26 rotates 'the necessary amount toimove into its second or lower position. As'will beunderstood, conditions of dust or rust occurring over apefioaer timemi'ght adversely: afie'ctthe pivotal connction between member 26 and the red 2150 that plunger avtion alone might be insuificient to cause the necessary amount of rotation. Spring insures that suflicient rotation takes place. Thirdly, the force provided by spring 45 assists the action of gravity in overcoming any resistance between member 26 and rod 21 so that the member 26 will be moved to its second or lower position. Lastly, the tension of spring 45 insures a pressure engagement between switch contacts 4!! and 42, thus providing a satisfactory electrical connection between the two contacts.

Thus it is seen that spring 45 is of particular value in the switch actuating portion of the invention since it tends to overcome conditions of dust, rust, etc. that are likely to occur over a period of time. It is to be appreciated that months or even years might elapse before a particular switch is actuated, and it is, of course, vitally important that the switch will properly operate whenever called upon to do so.

The foregoing fuse responsive switch is connected in circuit with the indicator components of the alarm system. One indicator component takes the form of a signal lamp mounted on the top of each fuse bank l5. Each fuse bank, in the equipment illustrated, comprises two symmetrical subsidiary banks of fuses located one on each side of central sheet I8. Actuation of the switch associated with a particular fuse bank [5 causes illumination of the signal lamp 5B associated with that fuse bank.

The circuit diagram of Fig. 7 shows one possible manner in which the switch mechanism may be connected in circuit with the indicator components of the invention. The input terminals to the circuit are indicated by the positive and negative symbols although, of course, alternating current could be used. The circuit including signal lamp 50 may be traced from the positive input terminal through switch contacts 40 and 42, lamp 59, the winding of a solenoid 5!, through an off-on switch 52 to the negative input terminal. The ofi-on switch, of course, is in the on position when the alarm system is in condition for use.

The other indicator component of the alarm system is an audio device such as a buzzer 54. The buzzer 54 is energized through a microswitch 55 actuated by solenoid 5|. From Fig. '7 it will be seen that the coil of solenoid 5l is energized when the switch contacts 40 and 42 are brought into engagement. Upon solenoid actuation of microswitch 55, current passes from the positive input terminal through the microswitch to buzzer 54, and from buzzer 54 through off-on switch 52 to the negative input terminal. It will be noted that the off-on switch 52 must be moved to its off position momentarily in order to de-energize solenoid 5| so that spring 56 associated with microswitch 55 may break the connection through switch 55 and thus de-energize buzzer 54. Referring again to the mechanical switch mechanism associated with each fuse bank l5, it will be seen that there is required only a slight manual movement of member 26 in order to recondition the alarm system after an instance of use. It is only necessary, following replacement of an overloaded fuse, to slightly raise member 26 and to rotate it so that it assumes its first or upper position on the rod 27. This movement separates switch contacts 40 and 42 and thus conditions the alarm system for subsequent use.

From the above description it is thought that the construction and advantages of this invention will be readily apparent to those skilled in the art.

Various changes and modifications may be made without departing from the spirit or losing the advantages of the invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. In combination with a fuse bank containing plunger type thermal fuses, a switch for energizing an alarm system for directing attention to the location of an open circuited fuse, said switch comprising an elongated member disposed in effective relation with the plungers of said fuses, a first switch contact on said elongated member, a second switch contact on said bank, said member being mounted for rotation and being rotatable upon engagement by the plunger of an open circuited fuse, said member also being movable along its axis of rotation, a cam element operable upon member rotation to permit axial movement of said member whereby said switch contacts may be moved from a spaced relation to a contacting relation, and a spring exerting pressure between said member and a point on said fuse bank whereby said spring cooperates in rotating said member, in causing axial movement thereof and in maintaining a pressure engagement between said switch contacts.

2. In combination with a fuse bank containing plunger type thermal fuses, a switch for energizing an alarm system for directing attention to the location of an open circuited fuse, said switch comprising an elongated member disposed in effective relation with the plungers of said fuses, a first switch contact on said elongated member, a second switch contact on said bank, said member being mounted for rotation and being rotatable upon engagement by the plunger of an open circuited fuse, said member also being movable along its axis of rotation, means for maintaining said member in an axial position with a space between said switch contacts, and means permitting axial movement of said member when said member is rotated by engagement therewith of the plunger of an open circuited fuse whereby said switch contacts are brought into engagement.

3. In combination with a fuse bank containing plunger type thermal fuses, a switch for energizing an alarm system for directing attention to the location of an open circuited fuse, said switch including a vertical rod extending in spaced relation with the plungers of said fuses, said rod having a horizontal portion at its lower end connected to said fuse bank, an elongated member having lugs that engage said rod whereby said member is rotatable about said rod upon engagement by the plunger of an open circuited fuse, a cam element associated with said member and the horizontal portion of said rod for normally holding said member in a first position, said cam element having a step therein that cooperates upon rotation of said member to permit said member to assume a second position, switch contacts that are spaced apart when said member is in first position and are in engagement when said member is in second position, and a spring exerting pressure between said member and said rod whereby said spring cooperates to maintain said member in first position, to effect rotation of said member following plunger engagement,

' to move said member to its second position and to maintain pressure engagement between said switch contacts.

4. In combination with a fuse bank containing plunger type thermal fuses, a switch for energizing an alarm system for directing attention to ans-gees the location-of an open r circu'ited fuse,1said switch comprising i-an elongated member ::disposed in effective relation with the plungersiof. said fuses, a first sw'itch contact on-said:elongated member, a second switch :contact on said bank; said member being mounted for longitudinal movement, means permitting longitudinal movement ot said member upon engagemenhof said member by the plunger-of an open circuitedt fuse, :and -a spring exerting -pressure between said member-and said bank whereby said spring 'coopera'tes i @to. insure longitudinal movement of said -m'ember upon plunger I action :and consequent. closure of said switch' contacts.

--5.- In combination-with a fuse bank containing plunger type thermal fuses a switch for energizing an"a1arm system' 'for-rzdirecting attention to theiocation of an open circuited fuse, said-switch cemprisingian elongated umember disposed in effective relation with the=p1ungers=of said fuses,

a fi'rst switch contact-on said elongated :memb'er,

a second sootclrcontactlomsaid saidimemher 1 being mounted tori-ilnngitudinalamovement. means permittmgidongiiaudinahmovementzof :said member upon engagement: 'ofissaid membemby-the plunger ofitaneiopenmircuited arise; whereby-etc effectr'closures of saidsswitch: contacts.

. iREEERENGES :GITED The following references are on-record in the file of this. patent:

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