US933769A - Arc-lamp having magnetizable electrodes. - Google Patents

Description

G. M. LITTLE.

ARC LAMP HAVING MAGNETIZABLE ELEGTRODES. APPLICATION FILED MAY 10, 1906.

933,769. Patented Sept. 14,1909. E1 14.

M ATTORNEY Gnonen M. LITTLE, or rirrssune, PENNSYLVANIA, assrenon 1'0 .wnsr-rnenousn ELECTRIC & MANUFACTURING COMPANY, A CORPCEATION OF PENNSYLVANIA.

ARC-LAMP HAVING- MAGNETIZABLE ELECTRODES.

Specification of Letters Patent. Patgnited Sept, 14, jlgtlg.

Application filed May 10, 1908. Serial No. 316,134.

T 0 all whom it may concern:

Be it known that I, GEORGE M. Lrr'rLn, a citizen of the United States, and a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Arc-Lamps Having Magnetizable Electrodes, of which the following is a specification.

My invention relates to are lamps and particularly to those in which electrodes containing magnetizable materials are employed.

The object of my invention is to provide means for neutralizing magnetic fields that may be produced by external means in electrodes of the character indicated.

Electrodes for are lamps are frequently composed of magnetic oxid of iron and oxids of titanium and chromium, or of other suitable substances, that are contained in iron tubes. In the use of such electrodes it has been found that the arc is frequently distorted and lengthened to such a degree as toseriously interfere with the operation of the lamp, and I have discovered that the distortion and lengthening of the arc has been the result of the magnetization of the electrodes by stray magnetic fields from the operating magnets of the lamps.

According to the present invention I propose to neutralize the stray magnetic fields by placing either a permanent or an electromagnet in a suitable relation to the magnetizable electrode.

Figure 1 of the' accompanying drawing is a view in elevation of an arc lamp that embodies my invention, a portion of the casing being broken away for the sake of clearness of illustration, and Fig. 2 is a diagrammatic view of the circuits of the lamp of Fig. 1.

An electrode 1, that may be composed mainly of magnetic oxid of iron and oxide of titanium and chromium, or of other. suit able materials, contained-within an iron or other magnetic tube 2, is adapted to be moved downwardly into engagement with a stationary electrode 3 and to be adjusted in position with reference thereto by any suitable means generally employed for this purpose. As here shown, the electrode is supported by means of" a clutch 4 that may be moved downwardly against the tension of a spring 5 by means of an electro-magnet having a winding 6. A pair of contact terminals 7 and 8 are interposed in the circuit of the magnet winding (5 and are adapted to be electrically connected by means of either of switch members 9 and 10, the former of which engages the contact terminals when no current is supplied to the lamp. The switch member 9 is provided with an operating magnet winding 11 that is connected in series with the electrodes 1 and 3, and the switch member 10 is provided with an operating magnet winding 12 of comparatively high resistance the terminals of which are connected to the contact terminals 7 and 8.

W'hen current is suppliedto the lamp it first traverses magnet winding 6, a resistance 13, and switch member 9. The clutch a: and the electrode 1 will then be moved downwardly until the latter engages the electrode 3, when a circuit will be established through the electrodes 3 and 1, a coil l l, and the winding 11. The winding 11 thereupon raises the switch member 9 and the high resistance winding 12 is thereby included in circuit with the winding 6.

The magnetizing efiect thus becomes so much reduced that the spring 5 is permitted to raise the clutch 4n and separate the electrodes 1 and 3. An arc is thus started which continues until the voltage applied to the winding 12 is increased to such an extent, by reason of the lengthening of the distance between the electrodes, as to enable its magnetizing efiect to raise the switch member 10, when the circuit of the magnet winding 6 will be established in the same manner as when starting.

lit will be observed that the magnet windings of the lamp are located in such close proximity to the upper end of electrode 1 that stray magnetic fields may magnet-12c the magnetizable materials and the iron shell of the upper electrode. lln order to prevent the distortion and lengthenmg of the are which has heretofore occurred as a result of the magnetization of the electrode,

vary approximately in proportion to the that may be produced therein by external stray magnetism. means comprising an eieotro-magnet wind- 1 claim as my invention: I ing that surrounds the electrode. 1. The combination with an arc lamp In testimony whereof, I have hereunto 15 electrode that contains magnetizable masubscribed my name this 1st day of Maya tielriall, of a magnet inding that surrounlds 1906-. v

t e e ectrode and is connected in series re ation therewith GEORGE M. LITTLE.

2. The vcombination with an arc lamp Witnesses:

electrode that contains magnetizable ma- OTTO S. SOHAiRER;

terial, of means for neutralizing magnetism BIRNEY HINES:

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