US1878153A - Electric resistance - Google Patents

Description

Sept. 20, 1932. A, LAMPL ELECTRIC RESISTANCE Filed Sept. 24, 1926 /n u 6? for:

Patented Sept. 20, 1932 UNITED STATES PATENT OFFICE ALFRED LAMPL, 0F BERLIN, GERMANY, ASSIGNOR TO NOMA ELECTRIC CORPORATION, OF NEW- YORK, N. Y., A CORPORATION OF NEW YORK ELECTRIC RESISTANCE Application filed September 24, 1926, Serial No. 187,602, and in Germany March 13, 1926.

This invention has reference to electric resistances and in particular to resistances of the kind in which the fusing or fritting property of comminuted, granulated, chipped or powdered metallic material and the reduction of their resistability at the electrodes above certain limits of electric voltage is utilized for the control and the variation of the electric resistance. From publications and from the patents of the applicant it has become known how to utilize the fritting property referred to of electric conductors which are introduced or sprinkled in the shape of powder, granules or chips in the form of a normally non-conducting shunt between electrodes, as automatically acting substitute resistances for serially connected current consuming or utilizing devices, such as for instance for serially connected incandescent lamps. Upon the breaking or interruption of a current consuming device, such as the filament to one of a series of lamps for instance, an automatic overbridging of the point of interruption is produced since the total voltage of the series is impressed on the shunt for said lamp causing a fritting, fusing or partial, imperfect melting of the granules into a conducting, fritted mass and the interruption of the current at the other serially arranged current consuming means is avoided.

For the purpose of regenerating or unfritting of a resistance of this kind, after it has assumed its operation, it is generally merely required to knock against the resistance a number of times or to shake or jar the same. With a certain degree of fineness of the metal particles there may be the difiiculty that by the prolonged keeping 'at rest of the metallic granulated or powdered material the entire mass will collapse to such a degree as to produce a more or perfect surface contact between the several metal particles, thus preventing the shunt from again becoming nonconducting upon again reducing the voltage. Moreover, in the case of a low tensionat the terminals and in view of the fact that'these elements will then fail to present a suiticiently of resistance against the passage of the current this fact and the heating by the permanently passing current which tends to fuse the particles will be a further cause of militating against the possibility of ready unfritting ot the device.

Now, it appears from further experiments of the applicant that these inconveniences and difficulties may be avoided by embedding the metallic granules, metal chips or metal powder in a solid binding material which by itself is not a conductor for the electric current, such as for instance gypsum, chamotte, burnt clay, concrete, cement, mortar and the like by this means electric resistances may be obtained which either present a very considerable electric resistance coefiicient or are adapted to oppose a certain definite degree of resistance to the passage of the current in accordance with the voltage or electric tension at the terminals of the resistance going beyond or remaining below a certain limit, these-called flitting-limiting voltage, that is, the voltage at which fritting of the particles occurs. In addition, a special exterior force or influence, that is to say shaking or vibration for instance, is no more necessary for the fritting and respectively for the unfritting of electric resistances obtained in this manner since upon reduction of the voltage, as when the lamp with the broken filament is replaced, the shunt is automatically unfritted and hence again becomes non-conducting. By this means electric resistances which in accordance with this invention comprise metallic particles securely embedded in relatively fixed positions in an insulating embedding or incorporating material and responding to the current only above a certain limit of tension'or voltage become particularly well adapted for the closing or for the interruption of electric circuits under the action of different tensions or voltages, and hence furnishes effective substitute resistances for serially connected current consuming'means.

Inasmuch as the limiting tension for the fritting action, assuming the same composition of the resistance material and substan-' tially identical shapes of the electrodes depends mainly on the relative distances of the electrodes it is possible to so grade the resistance that to every desired limiting tension radio-stations and the like.

there will correspond a certain shape and size of the resistance material, and inversely. Thus there is the possibility of utilizing the occurrence of different tensions in an electric circuit for the closing or the interruption of the same or even of other circuits, and moreover of producing certain desired results by the utilization of variations of electric tension and the closing or interruption of current effected thereby.

As an instance for the generic manner of utilization of the invention first referred to I may mention safety devices for the protection against over-tension and excessive voltages and for the protection against lightmng particularly in weak current systems, In such cases the ordinary spark gaps against lightning and the like may be substituted by a resistance of the kind described and inserted between the line to be protected and the ground and whose fritting limiting tension is above the normal operating tension of the system, but below the over-tension to be conducted away. By a suitable judicious series and parallel connection of resistance elements of the kind indicated it becomes also possible to protect systems of higher tension and of higher current strength during the normal operation thereof from danger of over-tension and lightning and without any loss of current.

Furthermore, the novel resistances according to this invention may be advantageously employed for various systems of space operation by electricity and for signalling purposes. By the employment of difierent tensions it is possible to close or open different electric circuits by means of resistance-relays which are tuned or adjusted for certain definite limiting tensions, and by this means certain predetermined actions may be produced at a distance from the operator, such as electric switching at a distance or the operation of automatic telephone apparatus or the like. All these are merely instances of the various possibilities of utilization of the fritting resistance referred to and operating as a tension relay, without limiting the invention to these examples which are merely given by way of illustration and exemplification of the various forms of embodiment which the invention may as-- sulne. One of the most essential advantages of the subject matter of the invention as compared with the construction of relays heretofore known resides in the fact that in view of the absence of all movable parts, such as magnets, windings and similar parts a very high degree of simplicity of the device is produced, combined with low cost of construction, great reliability and facility of operation.

- The invention will be further described with reference to the accompanying drawing showing by way of exemplification but without the intention of limitation several forms of embodiment and of utilization of resistances according to the principle of my invention.

Fig. 1 is a side elevational view of a pair of lamp sockets connected in series circuit and provided with shunts embodying the invention; one of the sockets being shown in cross section;

Fig. 2 is a longitudinal cross-sectional view of a lamp embodying the invention;

Fig. 3 is a partial, cross-sectional view of a lamp embodying the invention and illustratin a modified construction;

ig. 4 is a cross-sectional View of a modified form of resistor embodying the invention.

In Figure 1 I have illustrated two serially connected lamp fixtures or sockets 1 and 2 representing a portion of a plurality of seriallfy connected incandescent lamps. As appears rom the lamp fixture shown in sectional view, a substitute resistance or relay resistance 4 is disposed in a cavity of the lamp socket 3, such resistance comprising metal particles, such as for instance particles of iron, of brass, aluminium and the like and fixedly secured or embedded in an insulating embedding material and provided with the admission electrodes 5 and 6.

In the modification according to Figure 2 a correspondingly composed substitute resistance 4 is disposed in the lower part of the lamp socket of an electric incandescent lamp between the screw-threaded fixture wall 6 and a small metal tube 7, the entire mass being for instance introduced in a pasty or plastic condition and being allowed to solidify in the socket.

In the form of construction according to Figure 3 the correspondingly produced subsitute resistance 4 is introduced into the upper portion of the glass body 8 of an electric incandescent lamp and is protected by a special ballast resistance 9 which may for instance comprise a metallic filament or a resistance wire of substantially the same resistibility as the incandescent filament 10 of the lamp. In accordance with the arrangement shown in Figure 3 of the drawing the sensitive fritting resistance 4 is therefore protected against excessive strain by the fixed ballast resistance 9, so that the resistance 4 is merely operating as a kind of sensitive fritting valve and therefore may be selected of relatively small size.

Figure 4 illustrates the employment of a fritting resistance 4 with current admission electrodes 5 and 6 in connection with a casing 11 constructed according to this invention. This embodiment may be employed for instance as a lightning arrester or protecting means for weak-current systems and the like, being then disposed in parallel ormultiple connection with a lightning arrester 12 of the ordinary kind.

It should, of course, be understood that the invention is not limited to these few forms of application and embodiment herewith shown and described merely by way of illustration of the principles thereof, but it may be utilized for various other equivalent purposes and changes in construction and modification: may be made without deviating from the spirit and scope of the invention, except as otherwise stated in the appended claims.

I claim:

1. An electrical resistor comprising material electrically non-conductive below a predetermined voltage and conductive above said predetermined voltage and adapted to automatically again become non-conductive upon reduction of said voltage from above said predetermined voltage to below said predetermined voltage.

2. An electrical resistor comprising material electrically non-conductive below a pre determined voltage and conductive above said predetermined voltage and adapted to automatically again become non-conductive upon reduction of said volta e from above said predetermined voltage to elow said predetermined voltage, said material comprising metal particles.

3. An electrical resistor comprising material electrically non-conductive below a predetermined voltage and conductive above said predetermined voltage and adapted to automatically again become non-conductive upon reduction of said voltage from above said predetermined voltage to below said predetermined voltage, said material comprising metal particles, adapted to become automatically fritted upon raising the voltage to above said predetermined voltage and to automatically become unfritted upon reduction of said voltage to below said predeter mined voltage.

4. In combination with a pair of terminals adapted to be connected to an electrical device, a shunt for said device comprising material electrically non-conductive below a predetermined voltage and adapted to become conductive above a predetermined voltage, and automatically non-conductive upon reducing the voltage, from above said predetermined voltage to below said predetermined voltage.

In witness whereof I herewith afiix my signature.

' ALFRED LAMPL.

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