US1267199A - Incandescent-cathode arc device. - Google Patents

Description

C. V. FERGUSON.

INCANDESOENT CATHODE ARC DEVICE.

APPLICATION man SEPT. 90. ms.

1,267,199. Patented May 21,1918.

Fig. I.

AAAAAAAAA I""""l Inventor: Charles V. Ferguson,

His Jqttorney.

UNITED STATES PATENT OFFICE. cnmns v: motor, or scngncrnnr, mm roux, ABBIGNOB To onmn,

ELECTRIC COMPANY, A CORPORATION 01' NEW YOIK. INOANDESOEM-CATHODE ARC DEVICE,

1,267,199. ndi i m" Palm- Patented May 21, 1918. Application flied September 20, 1915. Serial No. 51,681.

To all whom it may concern: is pointed; and Fig. 3 illustrates a device Be it known that I, CHARLES V. FERGUSON, havin a mercury anode.

a citizen of the United States, residin at Re erring to Fig. 1 the discharge device Schenectady, county of Schenectady, tate consists of a sealed envelop 1 which consists of New York, have invented certain new and of glass, quartz or the like, and the cathode to useful Improvements in Incandescent-Cath 2 and anode 9, both of these electrodes being ode Arc Devices, of which the following is a sealed into the container in the usual manspecification. ner and consisting of hi hly refractory subthe spec1 c arrangement of cathode and cathode stem and connecte The present invention relates to electrical stances such, for examp e, as tungsten, tandischarge devices of the incandescent cathtalum, carbon and the like. The cathode 2 ode type having a gaseous filling, and its consists of several parts, namely, an arcing object is to provide a simple, rugged device tip 3, connected to a stem 4 havin a (lihaving a, commercially long life ameter small enough to afford enoug resist- My invention is particularly applicable ance to the conduction of heat to enable the to devices having an asymmetr conductivarcing tip 3 to operate at incandescence. ity, such, for example, as rect -s for alter- The stem 4 is connected to a current-convey nating current. ing conductor 5 sealed into a stem 6. The

hen an arc is operated in an inert atarcin ti should be so arranged and sup mosphere of gases or vapors from a cathode porte t rat the heat lost by conduction adapted to be independently heated by pas throu h the supporting stem consists of such 76 sage of current analogous to a lighting filaa sum 1 fraction of the total heat developed ment the startin of the arc can be convenby the cathode that the arcing tip is main iently accomplis ed, but this arrangement tamed at a uniformly high temperature by possesses a limitation in the fact that eleca comparatively small amount of ener trical disintegration may cause the filament Consequently with a given current the total 80 to wear away locally and break. voltage across the arc is lower than it would In accordance with one embodiment of be if: no section of reduced diameter were my invention, I have provided a discharge provided. This result can be conveniently device having a cathode comprising a rugobtained by reducing the diameter of a god electrode, adapted to be heated only small section 7 of the supporting stem adby passage of current through the gas, such, 3o1n1ng the arcing tip as shown in Figs. 2 for example, as a rod having a tip which is and 3. In some cases the cathode has a proportioned to operate at incandescence, to- P inted or sharpened tip, as shown in Figs. gether with means for initially starting an 2 and 3 t0 facilltate starting and secure are between the electrodes of the device grea er stability of the arc. whereby the cathode will be heated to in- N r he arcing ti of the cathode is procandescence. The incandescent tip may be vided the Starting lament 8 consisting of made large enou h to make electrical erorefractory material such as tungsten, tansion negli 'ble. Iy invention also includes talum or carbon spirally spaced about.the

to the cathode starting filament, the latter being electrically stem 4 at one end near the tip 3 as indicated, connected to the cathode and in close 'therthe end remote from the arcing tip of the ma] relation thereto while being located at a cathode being attached to a separate lead 5 greater distance from the anode than the sealed into the stem 6 of the device in the arcing tip of the cathode so as to avoid havusual manner. By this construction the ing t e arc emanate from the filament instartln filament is located a greater disstead of from the arcing tip of the cathode. tance rom the anode 9 than the arcing tip In the accompanying drawin Figure 1 of the cathode in order to guard against the illustrates diagrammatically a d ischarge dearc deserting the ti 3 and running to the vice suitable for rectifying alternating curstarting filament eit er entirely or 1n part. rent and provided with a starting filament; The anode 9 may have any convenient Fig. 2 illustrates a modification in which shape and may consist of refracto material the startin filament is omitted and the are such as tungsten or carbon or vo atilizable is started )y means of a high volta e dismaterial, such as mercury, as shown at 10 charge from the cathode which pre erably in Fig. 3. In a rectifier the anode should have a materially greater heat dissipating capacity than the cathode to enable it to remain below a temperature of about 700 C. at the normal operating current of the device.

In the preparation of the device the space within the envelop should be carefull exhausted of all gases and vapors, cure ing taken to remove electro-negative gases, such as oxygen or chlorin, or substances yielding electro-negative gases, for example, water vapor. A trace of oxygen does little harm when the electrodes consist of oxidizable metal, such as tungsten or 11101 bdenum as the oxygen combines chemical with'the heated electrodes to form non-v0 atile oxids. The envelop is filled with a gas inert t0 the electrodes, as, for example, argon, nitrogen, crypton, neon, hydrogen, at a pressure which may be between several millimeters and atmospheric pressure or more. These gases should be substantially free from electronegative gaseous impurities. For low voltage rectifier-s a gaseous pressure of 5 to 12 millimeters of mercury is desirable but no definite limit of gas pressure can be given as it will in general vary with the voltage upon which the device is operated and the character of the service required of the device. In some cases the gaseous filling ma be constituted by the vapor of a materia ordinarily a liquid, for example, mercury. The envelop should be proper y proportioned with respect to the energy consumed during the operation of the device to dissipate heat at a rate which will result in an operating temperature at which the vaporizable material as the desired vapor pressure.

The arc is started by heating the filament 8 to incandescence by suitable current introduced through the leads 5, 5 by the conductors 11, 12, from any convenient source, such, for example, as the secondary 13 of a transformer 14. When the filament has been heated to incandescence, a current of suitable voltage is impressed between cathode and anode. As shown in the drawing the device may be used to rectify alternating current supplied from the transformer secondar winding 15 through conductors 16, 17. he are initially runs from the incandescent filament 8 to the anode and serves to heat the starting tip 3 to incandescence both by heat conduction from the filament which is connected to the tip and by reason of the roximit of the ti of the are as well as the eated fi ament. he circuit of the starting filament me then be opened by a switch 18. The are w' I continue to operate from the incandescent tip 3 to waves of current being conducted by the device illustrated. The rectified current may be used for any desired purpose such, for example, as charging the storage battery 19. As the arcing tip 3 has a. relatively greater the anode, only half mass than the filament electrical erosion or disintegration will have but very little deleterious effect. The filament 8 is used only for a very short time when the device 18 started, hence the electrical disintegration of the filament is no ligible. For these reasons the device wifi have a commercially long life.

1n some cases, as shown in Fig. 2, the starting filament may be entirely dispensed w1th when the device is to be used only for relatively high voltages. In that case the arcing tip 3 is made shar or pointed to such an extent that the arc wi 1 be certain to start from the point of the electrode as cathode whena re atively high volta e is applied to the terminals of the device, or example, as by means of an auxiliary transformer winding 20. After the mam cathode has been heated to incandescence the switch 21 ma be again opened and the switch 22 closed. have found that by thus using a pointed electrode an arc may be started at a potential of about 60% as great as the voltage required to start with a large surface as cathode. In other respects the device shown in Fig. 2 is the same as that already described in connection with Fig. 1.

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

1. A refractory cathode for an electric arc device comprising a supporting stem, an arcing tip therefor of greater diameter than said stem, and a refracto conductor connected to said stem near said arcing tip and extending away from said tip.

2. A rectifier comprising a sealed container a filling of inert gas therein, a cathode, the tip of said cathode being proportioned to operate at incandescence and having electrical connections at one terminal only, a co'operating anode and means constituting part of said cathode for assisting the starting of an arc in said device whereby the ti of said cathode will be heated to incan escence.

3. An electrical arc device comprising a sealed container, a filling of gas therein having at the operating temperature of the device a vapor pressure materially in excess of several millimeters of mercur a cathode comprising a rod-shaped con actor of. refractory metal, comprising a stem and a tip of greater diameter to permit electrical erosion without deleterious efiect, a codperating anode having a materially greater heat-dissipating capacity than the cathode,

and means constitutin part of said cathode for assisting the starting of an arcin said device.

4. A rectifier comprising a' sealed container, a filling of inert gas therein, a refractory sharp-pointed cat ode proportioned to operate at mcandescence, comprising a supporting stem and an arcing tip of greater mass than said stem to permit electrical erosion without deleterious eifect, and a cooperating anode of lar r mass than the cathode, said electrodes eing proportioned to enable an arc to start from cathode to anode at a materially lower voltage than in a reverse direction.

5. An electrical are device comprising a sealed container, a filling of gas therein, a. cathode, the tip of which is proportioned to operate at incandescence and having an electrical connection at one end only, an anode, a refracto conductor electrically connected at one en to the cathode near the arcin tip and extending away from the anode, and connections for conducting current to said electrode.

6. An electrical are device comprising a. sealed container, a filling of inert gas therein at a pressure exceeding several millimeters of mercury, a cathode, the tip of which is proportioned to operate at incandescence and is electricall connected at one end only, an anode, a re ractory auxiliary electrode electrically connected at one end to the cathode near the arcing tip, extendin away from the anode, and spirally space about the cathode, and electrical connections for conducting current through said auxiliary electrode.

In witness whereof, I have hereunto set my hand this 17th day of September, 1915.

CHARLES V. FERGUSON.

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