US853492A - Process and device for controlling electric circuits. - Google Patents

Description

No. 853,492. I PATENTED M11214. 1907;

H. BECK.

PROCESS AND DEVICE PORVGONTROLLINGV APPLICATION FILED 11.27, 10

ELECTRIC CIRCUITS. 0e.

UNITED STATES PATENT OFFICE.

HEINRIOH BECK, OF MEININGEN, GERMANY.

Specification of Letters Patent.

Patented May 14, 1907.

Application filed January 27, 1906 Serial No. 298,131.

To all whom it may concern:

Be it known that I, I'IEINRICH BECK, a civil engineer, and a subject of the German Em eror, and residing at Meiningen, Duchy of axe Meiningen, part of the German Emire, have invented certain new and useful mprovements in Processes and Devices for Controlling Electric Circuits, of which the following is a specification.

My present invention has reference to a regulating resistance for the purpose of being included in the circuit of electrical apparatuses of any kind.

The new regulatin resistance may for instance be employe in arc-light-circuits. My new resistance is characterized by being based upon the principle that a thin wire vzhich consists of a material having a high t mperature coefficient, is employed as a resistarice and is ke t in a stretched position in the interior 0 a tube which has been evacuated or which is filled with indifferent ases. Among the materials possessing a 'gh coe'fiicient of temperature iron is to be considered in the first place. Upon being heated to a high temperature an iron wire or a wire'made from any other suitable material will present a higher resistance to the electric current than at a low temperature. Hence, if the tension is increased in an" apparatus circuit in which this kind of resistance is included, the said apparatus will consequently be fed with current of a higher stren th, and the regulating resistancewill there ore be heated to a higher temperature. In view of the regulating resistance possessing the property of presenting a higher resistance' to the passage of the current at an increased temperature, the tension will, however, decrease inthe apparatus-circuit very soon. Thus, for instance, if the tension eXistin between two arc-light-lamps burning wit 9 am eres, amounts to 80 volts, while-the tota tension or voltage in the circuit amounts to 110 volts altogether, the ballast resistance should amount to 3.3 ohms. If however for some reason, the pressure or tension at both lamps isreduced to only o0. volts altogether, the strength of the current, when an ordinary resistance of 3.3 ohms is made use of, would be immediatelyin creased to 15 amperes, so that the loss of pressure in the ballast resistance would now to volts. If howeveran iron rea Hsistan eof 33 .ohms is used, the resistance,

" 'all 01'. er conditions beingequal, is increased in consequence of the increased heating to such an extent, .that the required loss of pressure of 50 volts will already be obtained with about 10.5 amperes. Hence theresistance of the iron wire has been automatically' increased from 3.3 to almost 4.8 ohms. Similar conditions prevail in the case of variations of the pressure or tension occurring in the system. Furthermore the injurious decrease of resistance which is due to the consumption of the carbons by burning, is compensated by the use of a suitable iron resistance. This is of great importance, in view of this loss of tension or pressure amounting up to 8 volts in the case of long carbons.

Th'echaracteristic feature of this invention as compared with other controlling and regulating devices for adjusting the resistance of electric are light lamps, is the fact that in the new arrangement, herein described,

it .is not the resistance of the are of light,

which is balanced in the case of variations of the arc-light resistance, and also the fact that notonly the variations of resistance which are produced gradually by the consumption by burning, but also'the suddenly occurring variations of resistance which are compensated or bal'anced automatically. However, in order to produce good results the combination with an iron resistance is of particular importance. Thus for instance, if an electric current, the strength of which is slowly increased, isv made to pass through an iron wire of a certain definite length, a different value of the resistance is found for each value of current, the loading of the wire being' specifically strong. In an iron wire,

which presents a resistance of 1.5 ohms to current of 3 amperes, by actual measure-- ments the value of 1.7 ohms could be found with 5 amperes and of 1.9 ohms with 6 amperes and 2.3 ohms'with 7 amperes and of 2.7

ohms with 8 amperes and of'6.1 ohms with 10- amperes. By then causing the current to pass in the reverse order through the same values, the same values for the resistance are obtained as in the case of the progressive increase of the strength of the current, provided the wire is in the open air and provided it is not excessively strong. When it is desired, to produce great variations of resistance, the wire should be loaded to a highs ecific strength and it should be heated up to-a out red heat. On account of the considerable oxidation, produced at this teu'iperature, and on account of the variation of resistance of the ,resistance material consequent thereon, and of iron in particular, the use of stronglyloaded resistances for the purpose of annihilating certain quantities of energy is excluded in the open air. The resistance wire has therefore been inclosed in form of a spiral wire in evacuated receptzwles or in receptacles iilled with indil ferent gases and in this manner working has been successful with small strengths of current. lln the case of more considerable strengths of current however in the wire resistauces of the kind mentioned entirely different values for the resistance are obtained for decreasing values of the current, as compared with those values corresponding to increasing values of the current. The reason for this behavior is the fact that heat is stored up in the resistance wire itself and in the parts situated near to the said wire or surrounding the same. The stored-up amount of heat is not conducted away quick enough, so that, when the strengthof the current decreases, the temperature and consequently also the ohm-.resistance of the resistance material will decrease at a slower rate than the current itself, so that in consex uonce thereof, a dili'erent value of resistance for the same-value of current and at decreasing strength of current is found, as compared with increasing strength of current. This action becomes particularly noticeable when red heat is reached. If for instance, in the case of current strength increasing up to about 9 am )eres, the wire resistance is heated up to red beat at 7 ampcres, red heat will still be prevailing under ordinary conditions, when the strength of the current is decreased to 6 amperes. The energy which has been annihilated in the rcsistance,will be approximately equal in both cases.

In accordance with this invention the resistancesarc arranged in such a manner, that, when the strength of the current is decreased, as nearly as possible. the same values for the resistance are obtained, as in the case of increasing strength of current. This is accomplished by rcducingthe heat capacities of the resistance to the lowest degree, so as to avoid the before mentioned storing-u )of heat and the thereby ensuing unfavorable action of the resistance Wire. With this end in. view, the mass of the resisl ance wire will be kept as low as possible, that is to say, it is made as thin as possible and provision is also made for the conveying oil of the heat in such a manner, that the wire is capable of annihilatin as much energy as possible, before it is rought up to red heat or before it exceeds the admissible limit of iewing heat. These conditions will be. f ull illed. most conveniently by stretching the wire in a free and disengaged condition and out of contact with masses which are liable of storing-up heat, that is to say it is not laid in spiral windings in the interior of a glass vessel or the like, which is either evacuated or filled with an indifferent gas such as hydrogen. The spiral windings of the resistance wire are not recommendable for the reason, because a change of the relative osition. of the several spiral windings in re. ation to each other would take place when the wire is heated and in particular in the. ease of rather great strength of current, the said change of position in its turn being liable to cause the windings that are closetogether, to become more highly heated, resulting in a twisting of the resistance body or even the short-circuiting of some of the windings. The stretched-out, straight Wire will give off the excess of heat the more quickly, the more care. is taken to enable the receptacle surrounding the wire of storing-up as little heat as possible, which object can be attained by increasing the surface or by imparting to it a convenient shape or size in any suitable manner. The diflerence of temperature between the walls of the receptacle and the wire,"which has been heated up to red heat, should be as high as possible. In order to take into account the extending of the wire occurring when the freely stretched-out wire is heated, and in order to always retain the said wire for its whole length in a central position at the interior of the receptacle and at the same distance from the walls of the receptacle, one end of the resistance wire is kept stretchedout by a wei ht in accordance with my invention; or t e same purpose. may be accomplished by springs acting upon one or both extremities of the said wire. By this means the uniform cooling of the wire for its entire length is also insured and shortcircuiting or breaking of the walls of the receptacle is prevented, When it is desired to use special supports for the wire, a very small heating capacity should be .imparted to the said supports.

A form of construction .of the resistance in accordance with this invention and suitable for an electric arc lamp of 9 amperes consists of four tubes of moderate size, -two of which are arranged in parallel series.

Upon the aceom anying drawing the subject matter of my invention isshown in two forms of construction.

Figure 1 illustrates in longitudinal elevation a regulating resistance, .arran ed in the interior of a glasss tubc; Fig. 2 s owing a regulatin resistance. in section, arranged inamcta tube.

In the tube shown in Fig. 1, a straight, single iron wire I) is stretched out in the intenor of a g1ass ,tubc a, the Wire being loaded at its 'lower end by a wei ht ,6, so as to be kept in a stretched condition. The lower terminal (I for the admission of the current the insulating pieces h.

outside by an insulating collar 1.

inside and on the outside,in order to effect a 3 better absorption of heat and a better radia- Y tion to the surrounding atmosphere. In this form of construction also the resistance wire b is kept taut by a weight 0, which may also be replaced by a suitable combination of springs. cl is the spiral wire for the admission of current into the resistance wire I) and f is a piece of thread which is intended to prevent swinging of the weight durin transportation. The spiral wire for the a mission of current is secured at its lower end to a metal screw g, so as to constitute electrical connection, a disk '11 which fits snugly in the tube a being secured to the metal screw by means of a nut 7c and insulated therefrom by means of The stem of the screw 9 projects throu h the bottom cover 1) of the tube and is insu ated therefrom at the Onto the outer free end. of the screw g the connecting contact piece 0 and the nut m are secured by suitable screw threads. The s ace between the closely fitting disk i and t e cover 1) is preferably filled with oil or with mercury in order to produce a better tightening in relation to the upper part of the tube a which has been evacuated or which is filled with indifferent gases. In the case of mercury being used as a tightening material the screw 9 and the nut is are inclosed in insulating material. In the form of construction shown in the drawing, one of the terminals is formed b the metal tube itself. In accordance wit the strength of the current \severaltubes ofcertain length are connected to each other.

What I claim and desire to secure by Letters Patent of the United States is v 1. An electric regulating resistance for apparatus circuits, a resistance wire, consisting of material wlth a high coefficient of temperature and kept stretched-out in a tube, the tube being evacuated or filled with indiiferent gases, means for maintaining the wire'in a stretched condition, substantially as described and for the purpose set forth.

2. An electric regulating resistance for apparatus circuits, a resistance wire of material with a high coefiicient of temperature, being stretched out in a tube, the tube being thinwalled and being of metal and being evacuated or filled with indifferent gases, means for keeping the wire in a stretched condition,

substantially pose set forth.

3. An electric regulating'resistance for apas described and for the purparatus circuits, a resistance wire of material with a high coefficient of temperature, being stretched out in a tube, the said tube being of ing the wire in a stretched condition, a convmetal and being thin-walled, means for keepnesting screw, projecting from the tube and insulated therefrom, substantially as described and for the purpose set forth.

4. An electric regulating resistance for apparatus circuits, a resistance wire of material with a high coefficient of temperature, being stretched out ina tube, the said tube being of metal and being thin-walled, means for keeping the wire in a stretched condition, a connecting screw, rojecting from the tube and insulated there om, a dlsk fitting snugly in the said tube and. insulated from the above mentioned connecting screw and arranged in the interior of the tube, a closely fitting cover at the lower end of the tube, means in the space between the cover and the closely fitting disk in the interior of the tube for the pur 'ose of tightening the tube, substantially as escribed and for the purpose set forth.

5. An electric regulating resistance for apparatus circuits, a resistance wire of material with a high coefficient of temperature, being stretched out in a tube, the tube beingfhinpurpose set forth.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

HEINRICH BECK.

Witnesses:

ALMA LAR BERTA HAMMANN;

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