US2062669A - Fuse indicator - Google Patents

Description

F. Q. LA EMM?! FUSE INDICATOR Filed Aug. 25, 1935 Patented Dec. l, 1936 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to electrical fuses, especially to electricalfuses of the cartridge type, and more particularly to an indicator for such fuses which acts to give information as to the integrity of the fusible element.

Itis well understood by those skilled in the electrical art that safety requires all circuits which carry or are capable of carrying an appreciable amount of current must have safety devices inserted in them to prevent an excessive flow of current under abnormal conditions.

A common safety device ls the well known fuse made of a strip of metal which will melt upon the now therethrough of an undesirable heavy current.

Fuses are made of many forms amongst which is the cartridge fuse which may be either of the ferrule type or the knife blade type.

In either case it is convenient and desirable to have means of simple form by which the fact that the fusible metal has melted may be indicated without removing the fuse from its position and disassembling it.

Integrity indicator means have been devised for application to both the ferrule type and the knife blade type of fuse, but these indicators are of a form which does not insure a positive and unfailing retention in position upon the fuse where extreme vibration occurs.

A principal object of applicants invention is the provision of an indicator applicable particularly to fuses of the knife blade type by which the integrity of the fusible element of the fuse may be ascertained by a visual inspection without disassembling the fuse or disturbing the position thereof, and which will be of such a form that no Vibration, however extreme, will cause the indicator to become separated from the fuse.

Other objects and advantages will appear as the description of the particular physical embodiment selected to illustrate the invention progresses, and the novel features of the invention will be particularly pointed out in the appended claims. l

In describing the invention in detail and the particular physical embodiment selected to illustrate the invention, reference will be had to the accompanying drawing, and the several views thereof, wherein like characters of reference designate corresponding parts throughout the several views, and in which:

Figure 1 is a side elevational view of a conventional knife blade cartridge fuse in place in the usualand conventional clips with an indicator embodying applicants invention shown therewith; Fig. 2 is a cross-sectional view of the device as shown by Fig. 1 on the plane indicated by the line II-II of Fig. l, viewed in the direction of the arrows at the ends of the line; Fig. 3 is a perspective view of applicants indicator.

Numeral I designates an ordinary and conventional mounting panel upon which are the ordinary and well known binding bolts 2 and 3, for attaching the conducting wires 4 and 5 of a circuit in which a fuse is to be inserted. Bolts 2 and 3 10 are connected by means of metallic strips 6 and 'I to the usual fuse clips' 8 and 9.

A usual and conventional form of knife blade cartridge fuse ID, having blades II and I2, and metallic caps I3 and I 4, and metallic ferrules I5 15 and I6, is positioned connecting the clips 8 and 8.

In order to visually indicate the integrity of the thermal element of the fuse I0, applicant provides an indicator which embodies a lamp I'I. This lamp Il, in accordance with applicants invention, is connected between the knife blades II and l2. When the thermal element of a fuse Ill is intact the lamp exhibits no glow but when the thermal element of the fuse Ill has been destroyed the lamp l1 becomes illuminated.

Applicant `provides a metallic arm I8 formed with a slot I9. This slot I9, as best shown in Fig. 2, is adapted to embrace a blade of the fuse. 1t is also of a thickness such that it may well be positioned between a cap as I3 and a clip as 8. 30 When the arm I3 is in the position as shown by Fig. 1, it is impossible to remove the arm from the fuse without rst removing the fuse from the clip.

For making electrical connection to the other 35 fuse blade applicant prefers a metallic spring clasp 2l, best shown in Fig. 3; This metallic spring clasp may be readily pushed on to the cap I4 or removed therefrom.

Between the arm i8 and the spring clasp 2| 40 applicant preferably provdesra supporting covering and protecting insulating tube 22. This tube is connected at one end to the arm I8 and at the other end to the' spring clasp 2l in any suitable and appropriate manner. Applicant 45 prefers to employ metallic bushings 23 and prefers to rigidly attach the bushings to the tube 22 by means of rivets as 24 and to then rivet as by rivets 25 the arm I8 and the spring clasp 2| to the bushings 23.

The lamp Il is preferably of the glow type having two electrodes therein, 2G and 33, and having two terminals 21 and 28. One of the terminals 21 is electrically connected to the arm I 8. The other terminal 28 is connected to a 55 leak resistance 29 and by means of a conductor 30 to the spring clasp 2|.

The connection of terminal 21 to arm i8 and conductor 30 to spring clasp 2| is preferably effectuated by means of eyelets, as li, which pass through the arm and spring clasp and are upset at each end. After the eyelets 3| are upset, the terminal 21 and the conductor 30 are securely held in place by a drop of solder as 32,

From the above description it will be readily seen that the indicator of applicants invention is of a form such that it may be placed in position upon a knife blade cartridge fuse with great facility before that cartridge fuse is placed in clips, but after the cartridge fuse is placed in clips it is impossible to remove the indicator, so that vibration, no matter how severe, would not cause the indicator to become separated from the fuse.

Although I have particularly described one particular physical embodiment of my invention, and the principle and construction 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 an integrity device for a cartridge fuse, in combination: a metallic arm formed with' a slot adapted to receive a fuse blade and be positioned between a cap of a fuse and a fuse clip whereby the arm cannot be removed except when the fuse blade is out of the clip; an electrical indicator having two terminals, one of the terminals electrically connected to the said arm: and means for electrically connecting the other terminal to the other fuse blade.

2. In an indicator, for a cartridge fuse of the type having a blade on each end and a cap surrounding the blade adapted to be held in fuse clips, in combination: a metallic arm formed with a slot adapted to receive a fuse blade and be positioned between a cap and a clip whereby the arm cannot be removed from the blade without first removing the fuse blade from the clip; an electrical indicator having two terminals; means for electrically connecting one of the terminals to the arm; a metallic spring clasp adapted to embrace the cap on the end of the fuse remote from the arm; and means for electrically connecting the other terminal of the indicator to the metallic clasp.

3. In an indicator for a cartridge fuse, in combination: a metallic arm formed with a slot adapted to receive a fuse blade and be positioned between a cap ofi-a fuse and a fuse clip whereby the arm cannot be removed from the blade without first removing the fuse blade from the clip; an indicator lamp forming electrical connection with the arm and supported thereby; and means also connecting the lamp electrically with the other blade of the fuse.

FRANK C. LA MAR.

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