US1989482A

US1989482A - Fuse integrity indicator

Info

Publication number: US1989482A
Application number: US631438A
Authority: US
Inventors: Mar Frank C La
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-09-02
Filing date: 1932-09-02
Publication date: 1935-01-29
Anticipated expiration: 1952-01-29

Description

Jm 935- F. (2. LA MAR 1,989,482

FUSE INTEGRITY INDIC'ATOR Filed Sept. 2, 1932 6 l 36' .7/ I w Z3 5 -ZZ30 mmvsm'om.

Patented Jan." 29, 1935 UNITED STATES PATENT OFFICE I I l 1 FUSE mrsc im mmcsroa I v M 0. LI Mar, New York, N. Y.

"91 M011 September I, 1 32, Serial N0. 831,438

' 8 Cum]. ((1 200-421) This invention relates to electricity, particularly to electrical conduits and housings, and more especially to devices known as distribution and fuse cabinets. g

It is well known that, at the present time, it is largely the custom to originate a plurality of electric circuits at one distributing point. These circuits at the point of origin are protected by thermal fuses. In order to promote the safety of those who have occasion to work about such distribution cabinets or panels, it is the custom in many cases, to so construct the distribution panels that they are what are known as "dead front", that is, normally no conducting parts .carrying current are so exposed that a person may accidentally touch them.

The parts exposed toview are, panels of insulating material carrying upon their rear face the fuse structure which is inserted in a circuit. When it is desired to ascertain whether or not a fuse is intact it is necessary to remove both the insulating froht facing or panel and the fuse itself. when the fuse is removed it is only by the use of supplementary apparatus that one is enabled to determine whether or not the fuse is intact. This is exceedingly troublesome, and so troublesome that the average householder is quite unable to apply proper tests to determine the integrity of a fuse under such conditions.

Attempts have been made to overcome the difficulty by providing small orifices in the insulating face or panel in which the pointed end of a conductor including a lamp may be inserted which thereby comes in contact with portions of the electrical circuit of opposite polarity, but

this method has proved rather unsatisfactory.

A principal object of applicant's invention is to provide a construction of dead front electric circuit distribution box which will be such that the integrity of a fuse hidden behind the dead front may be ascertained even without removing the dead front.

In describing the invention in detail and the particular embodiments selected to illustrate the invention reference is had to the accompanying drawing and the several views thereon in which like characters of reference designate like parts throughout the several views and in which:

Figure 1 is a front elevational view of a panel box with a portion of the cover removed to more clearly show the internal construction; Fig. 2 is a cross-sectional view of the device as shown in Fig. i, on the plane indicated by the line II-lI of Fig. I, viewed in the direction of the arrows at the ends of the line; Fig. 3 is a cross sectional view of the device, "as shown by Fig. 2, upon the plane indicated by the line III-.411, viewed in the direction of the arrows at the ends of the line; Fig. 4 is a view from. the rear of a I dead front blade.

The distributing box of applicant's invention preferably includes a metallic box frame 1 having a rear wall 2, side walls 3 and 4: top and bottom walls, only one of which, the bottom wall 5, is shown, and a front wall designated as a whole by 6. The front wall is formed in two parts,- a part 7 hinged at 8 which covers the entire front of the box but which is apertured to receive a door 8 hinged as at 9. By this construction the hinged front may be swung on. the hinge 8 so as to expose the entire inside of the box to facilitate work therein while for the ordinary insertion or replacement of a fuse the supplementary door 8, only, would 'be moved upon swing-hinges as 9.

Within the box, bus bars as 10, 11 and 12 are suitably positioned and insulatingly supported from contact with the metal of the box.

Forwardly of the bus bars an insulating frame work, designated as a. whole by 13, is mounted. This frame work is-supported from the back or rear 2 of the distribution box by the projections, as 14 and i5, fastening to a mounting plate 16 Ivghioh is in turn attached to the rear face of the x. If it is desired to make connections to one of the bus bars a metallic double pronged member 17 is attached to a bus bar. as 11, by any suitable means, as by screw 18, and another two pronged member, as 19, is positioned on the insulating frame 13 a proper distance from member 17, that is, a distance about the length of a fuse to be used. The connection to double pronged member 19 for the circuit is made by a conductor as 21. a

In order to inserta fuse between members 1'! and 19 a metallic member 22 is mounted on the rear of an insulating panel 23. This metallic member carries two

clips

24 and 25 positioned to engage with the two

prongs

28 and 27 of the metallic member 17 connected to the bus bar 11. In addition the metallic member 22 carries a clip 28 adapted to receive the knife blade 29 of a knife blade fuse. Of course it is to be understood that the showing of clip 28 for the reception of a knife blade fuse is not intended to excludethe use of a clip suitable for receiving the end of a ferrule type fuse. I

In order to connect with the double pronged m mber 19 a metallic member 29' is positioned on the rear of the insulating panel 23. This member 29' is constructed exactly like the member 22, in that it affords clips for receiving the two prongs of member 19, and also a clip for receiving a knife blade corresponding to the knife blade 29 of the fuse 20.

From the above description itfwill be seen that a fuse; as 20, may be inserted in the clips attached to the rear of an insulating panel, as 23, and then that panel together with the fuse may be positioned, as shown in Fig. 3, with the clips on its rear face engaging at one end the prongs of the metallic member connected to a bus bar, and at the other end the prongs of a metallic member connected to a conductor and thereby the fuse will be connected in circuit between the conductor and the bus bar so that when the panel 23, or dead front, is in place all of the parts carrying current are covered and out of the way of accidental contact with a person.

The construction hereinbefore described may be duplicated as many times as is necessary to provide the necessary number of fuses in branch circuits and the panels, as 23, when in place will form a continuous covering, so that no parts carrying current are exposed.

All of the parts hereinbefore described are old and well known.

Heretofore panels as 23 have been provided with orifices, one over each of the metallic members 22 so that a small pointed conductor may be inserted therein so as to come in contact with the metallic member 22. If two conductors were so placed in proper orifices and a lamp is connected therebetween one could learn whether or not the bus bars are active, that is, are impressed with a difference of potential, but such a manipulation is beyond the skill of the average householder. Furthermore, such operation would not give indication as to the integrity of the fuse.

In order to indicate the integrity of the fuse 20 and obviate the necessity of removing the panel carrying the fuse in order to ascertain the condition of the fuse, applicant has provided a lamp 30. This lamp, which is preferably of the low potential, two electrode, discharge type filled with an inert gas, such as neon, is positioned with one end resting in a cavity 31 of the insulating panel 23. This cavity connects with an orifice 32 which is visible from the outside of the panel. A suitable holder 33 is fastened to the panel to hold the lamp securely in place. One terminal of the lamp is connected by a conductor 34 with the metallic member 22. The other terminal of the lamp is connected by a conductor 35, having a resistance 36, preferably of the grid leak type, inserted therein, to the metallic member 29'.

The lamp 31, as described, is connected across, or in shunt of the fuse. Normally the lamp is not lighted due to the relative resistance of the lamp and its circuit and that of the thermal element of the fuse, but when the fuse is destroyed, as by an excessive flow of current, then sufficient current passes through the lamp to light it. One

opening the door 8' of the case and looking at the orifice 32 will immediately detect that orifice in which a light appears showing that alamp is burning. Under such conditions all that is necessary to be done is to remove the panel, take out the old fuse and replace it with a new one and then replace the panel as it was.

The detection of a blown fuse by applicant's device is merely the detection of a lighted lamp, so that it may be done by anybody. Furthermore, no accessory apparatus whatsoever is needed.

Although I have particularly described one particular physical embodiment of my invention and explained the principle, construction and mode of operation thereof, nevertheless, I desire to have it understood that the form selected is merely illustrative but does not exhaust the possible physical embodiments of the idea of means underlying my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a distribution box for electric circuits of the dead front type including an insulating panel upon which a fuse is mounted between circuit clips, the combination of a lamp mounted on the rear face of said panel, being positioned back of an orifice in the panel, and connected between the circuit clips and normally unlighted but adapted upon the destruction of the fuse to be lighted and will then be observable through said orifice from the outside of the panel, said insulating panel being readily removable from said box, thereby removing said fuse and lamp from theelectrical circuits, for convenient inspection, adjustment and replacement.

2. In a distribution box for electric circuits of the dead front type including an insulating panel upon which a fuse is mounted between circuit climps, the combination of a low potential two electrode, neon filled, discharge type lamp mounted on said panel and connected in series-with a resistance between the said clips and positioned back of an orifice in the insulating panel, said lamp becoming luminous only upon the failure of the fuse, whereby the integrity of the fuse may be ascertained without disturbing the panel, said insulating panel being readily removable from said box, thereby removing said fuse and lamp from the electrical circuits, for convenient inspection, adjustment and replacement.

3. In a distribution box for electric circuits of