US390310A

US390310A - James avaed packard

Info

Publication number: US390310A
Authority: US
Publication date: 1888-10-02
Anticipated expiration: 1905-10-02

Description

(No Model.)

J. W. PACKARD.

ELECTRICAL TESTING APPARATUS.

10.890818 Patented 008. 2, 1888.

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UNITED STATES FFTQE@ PATENT ELECTRICAL TESTING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 390,3l0I dated Qetober 2, 1888.

Application tiled May 4, 1888. Serial No. 972.803.

To ctZZ whom, it may concern.'

Be it known that I, J AMES WARD PACKARD, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Electrical Testing Apparatus; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it a1 pcrtains to make and use the same.

My invention consists in asuitable arrange ment of electrical circuits and contact-making devices by which a circuit which is being supplied with a current from any suitable source for the purpose of varying its resistance may be cut out from such source of current and thrown into circuit with a suitable testing device without moving any of the various parts of the apparatus other than the lever of the cut-out or switch.

The drawing represents my apparatus as it may be employed in the process of treating the carbon strips which are to be used in the manufacture of incandescent electric lamps. C is such carbon strip immersed in the carbon solution contained in tank T. From the dynamo D, or other suitable source of electricity, the current Vfollows the direction of the arrow through the contact E', the branch A of the cut-out lever, the trunnion R, the standard S, the binding-post K,th rough the carbon C, back through the bindingpost-K, the standard S', through its trunnion to the branch A'Z of the cut-out lever, and thence by way of the contact E to the other brush of the comniutator of the dynamo The passage of the current through the carbon C while the latter' is immersed in the car bon solution in the tank T causes the carbon to deposit upon the strip, and thus increasing its cross section it gradually diminishes its electrical resistance. It is desirable to test this electrical resistance from time to time Without removing the carbon strip from the tank or receiver in which it may be placed. To do this I have devised the following arrangement of circuits and contact making pieces, illustrated in the drawing, and now to be described.

To test the carbon in the manner desired, the operator presses down upon the button at (No model.)

the end of the branch A of the cut--out lever. Thisl first raises the branches A/ and A2 from off the contactpieces E' E, and thus cuts out the source of supply represented by the dynamo D. Continued movement of the cut-out lever brings the branches A A2 against the contactpieees F F', thus throwing the carbon Cinto circuit with the connections V V/,which introduce the said carbon C into the circuit of one of the branches of the W'heatstone bridge, 1 2. In the other branch of the said \Vheatstonc bridge is an adjustable resistance, NV, which may be set at that point to which it is desired to reduce the resistance ot' the carbon strip G. At the same moment that the branches A A2 of the eut-out lever close the circuit by contact with the parts F F the part L, at the other end ofthe cut-out lever, touches the contact-piece L' and closes the circuit of the galvanometer G through the connections M M and the branch A of the cutout lever. The three parts A A A2 of the lever are insulated one from another by the insulatingblock I. The Vheatstonc bridge is supplied by a suitable current from the battery B. Throughout the apparatus the current follows the direction indicated by the arrows.

It will be seen that while the testing portion of my apparatusis idle the circuitthrough the galvanometer is broken, and that such circuit is only closed at the Very moment when the resistance which is .to be dctcrmincdisintroduced into one branch of the Vheatstone bridge connection. Thus a galvanometer of the most delicate construction may be used, and its adjustment is not destroyed by continued passage of the current through its coils with the usual heating effect. Moreover, as the carbon strip is not removed during the operation, there is no possibility of breaking it, and if the process of varying its resistance has not been carried sufficiently far, as shown by the test, it is resumed without 'interruption by simply withdrawing all pressure from the button at one end of the cutout lever, when" the greater weight of the other end ol' the lever in the construction shown will cause it to assume the position shown in the drawings, andthe source of current, D, will again be thrown into the circuit. Ot' course it would be possible to accelerate the action of the key or cut-out lever by means of a spring in the ICO usual way, which is too well understood to need illustration.

The carbon strip Gandits connections leading to the cut-out lever I call the work-circuit, while the dynamo D, or its equivalent, and its connections lead ing to the cut-ont lever I call the main-current-supply circuit.

VhileI haveshown and described, as above, the adaptation of my invention to that particular arrangement of sub-circuits in shunt relation one to another, which constitute what is called a Wheatstone bridge,7 it may evidently be applied to any arrangement of subcircuits within the electrical or magnetic field of which a tell-tale or indicating device is placed. Thus in that portion ofthe figure drawn in dotted lines I have illustrated its application to another arrangement of sub-circuits which operate on the ordinary form of different galvanometer.

In the modification thus shown in dotted lines the current for testing purposes is supplied from the battery b. When the cut-out lever is pressed down, the current follows the respective directions indicated by the arrows. A part goes over the line V', through the work-circuit of the carbon strip C, as before described, along the line V, through one coil, c', of the differential galvanorneter, through the connections q' and m to the part A of the cut-out lever, thence through the contacts L and L and the connection m back to the other pole of the battery b. A second part of the circuit is shunted over the branch p, through the adjustable resistance w, and the other coil c of the differential galvanometer back by the connection q and line m', through the cut-out lever,along the path before traced to the other pole of the battery.

As the resistance of the carbon strip C is greater or less than that of the ascertained resistance w, lcssormore current will go through the coils c and c and the galvanometerneedle g will move under the influence of the preponderating coil. An advantage possessed by this particular arrangement is that the battery b is kept on open circuit at all times when not engaged in the actual useful work of testing, and therefore its energy is cconomized to the highest possible degree.

Having therefore described my invention both in essence and detail, what I claim as new, and desire to protect by Letters Patent, 1s-

l. In an apparatus for electrical testing, the combination ofthe work-circuit, the main-current-supply circuit, and a Wheatstone bridge supplied with an independent current from a second source, together with a suitable cutout, which, by one movement of the lever,cuts out the work-circuit from the main source of supply, throws it into circuit with one branch of the W'heatstone bridge, and simultaneously closes the galvanometer-circuit of the bridge, substantially as described.

2. In anapparatus for electrical testing, a Vheatstone bridge, having an ascertained resistance in one of its branches, while the circuit through its second branch and the circuit through its galvanometer are normally broken, together with a cutout, which, by one motion of the lever, simultaneously closes the galvanometer-circuit and introduces into the second branch of the bridge the unknown resistance which is to be tested, all in combination, substantially as described.

3. In an apparatus for electrical testing, the combination ofthe worlccircuit, the main-current-supply circuit, and an arrangement of sub-circuits placed in shunt relation to each other,iu one of which sub-circuits there is an ascertained resistance, and a current-indicating device within the influence of the currents iowing in the said sub-circuits, together with a suitable cutout, which,by one movement of the lever, cuts ont the work-circuit from the main source of supply, throws it into one of the subcircuits, and simultaneously closes the remaining sub circuits, whereby the resultant effect ofthe currents thus shunted through the various sub-circuits will show by the currentindicating device the relation of the work-circuit resistance to the ascertained resistance, substantially as described.

4. In an apparatus for electrical testing, the combination ot'a work-circuit, a main-currentsupply circuit, and an arrangement of subcircuits such as shall constitute an indicating or tell-tale device, together with a suitable cutout, which,by one motion of the lever,cuts out the Work-circuit from the main-current-supply circuit and throws the work-circuit into connection with the tell-tale device at the same time that it closes allof those subfcircuits constituting the tell-tale device which are normally open, substantially as described.

In testimony whereof I affix my signature in presence of witnesses.

JAMES WARD PACKARD.

Witnesses:

W. D. PACKARD, ED. BEEsLEY.