US3521114A - Automatic starting arc lamp - Google Patents
Automatic starting arc lamp Download PDFInfo
- Publication number
- US3521114A US3521114A US764103A US3521114DA US3521114A US 3521114 A US3521114 A US 3521114A US 764103 A US764103 A US 764103A US 3521114D A US3521114D A US 3521114DA US 3521114 A US3521114 A US 3521114A
- Authority
- US
- United States
- Prior art keywords
- tube
- electrodes
- arc
- electrode
- lamp
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B31/00—Electric arc lamps
- H05B31/02—Details
- H05B31/30—Starting; Igniting
- H05B31/305—Ignition devices
Definitions
- This invention relates to light sources and more specifically to a means for improving initial arc striking in a carbon electrode light source.
- Arc carbon electrodes are employed in devices wherein the light which is in the crater region of a positively polarized carbon electrode is employed as a source of illumination.
- Such devices include search lights, motion picture projector lamps, solar simulation apparatus and the like. While these devices function extremely well in operation, starting the arc is sometimes a time consuming task, particularly if manual manipulation of the electrodes is employed.
- US. Pat. 3,256,459 discloses an arc lamp in which a conductive fusion bridge spans the gap between electrodes and forms a low resistance electrical path therebetween.
- the fusion bridge is shaped such that its cross sectional area progressively increases axially in the direction of one or both electrodes.
- a starting voltage vaporizes the bridge from the minimum cross-sectional area outward toward the electrodes thereby creating a progressively larger gap.
- Such a construction is costly, has a poor shock resistance, and requires expensive support and alignment equipment.
- the objects of the invention are accomplished by the use of an annular refractory tube which is positioned between and in contact with the arc electrodes.
- the tube is easily attached to the electrodes and is automatically ejected when the are is struck.
- the electrodes may be spaced a proper distance, and no further movement is needed to strike an arc. Thus, manual effort by an operator is not required.
- the tube is preferably composed of a major amount of a carbonaceous material such as carbon or graphite since this material provides good electrical conductivity and excellent thermal resistance. This latter property permits the tube to withstand the extreme temperatures in the arc region so that the tube can be used again after being ejected from the region of the arc.
- a carbonaceous material such as carbon or graphite since this material provides good electrical conductivity and excellent thermal resistance. This latter property permits the tube to withstand the extreme temperatures in the arc region so that the tube can be used again after being ejected from the region of the arc.
- the manner in which the tube may be afiixed to the electrodes is an important advantage of this invention since a minimum of assembly time is employed. Because the tube is hollow, it is readily placed over the arc end of the electrode and this placement is virtually independent of the shape of the electrode since the tube can be fabricated with an inside diameter large enough to fit around such electrodes. However, since electrodes of this type are often provided with a tapered end portion, the tube can be situated over the pointed segment of the tapered portion without difficulty. In addition, a recess may be provided in one or both of the electrodes at the arc end and the tube can be positioned partially within the recess and supported by the lower lip of the recess.
- the tube is quickly positioned on but not rigidly secured to the electrodes and spans the gap between electrodes.
- the contact between tube and electrodes is suflicient in this assembly to provide a low resistance path for electrical current. Therefore, when a voltage is applied to the electrodes, current passes through the tube and between electrodes.
- the initial surge of current causes local arcing to occur along the inner walls of the tube and across the dielectric gap between electrodes, that is, down the center of the tube. An arc is thereby struck almost immediately after the initial current surge passes through the tube walls.
- the breakdown of the dielectric which is usually air, is accompanied by an expansion of the air along the path of the arc. This expansion exerts a force on the tube sufficient to force it from its loosely held position on the electrodes and causes the tube to drop away. This phenomenon occurs automatically and Without operator assistance thereby enhancing the operation of the system.
- FIG. 1 is a perspective view of part of an illumination lamp employing a refractory tube for self-starting
- FIG. 2 is a plan view in cross section of a refractory tube suitably employed in the invention
- FIG. 3 is a front elevation view of the tube in FIG. 2;
- FIG. 4 is a front elevation view of another refractory tube suitable for use as a self-starting component.
- FIG. 1 an arc lamp comprising an electrode 12 which rests in holder 14 and a second electrode 16 spaced from electrode 12 and positioned with its longitudinal axis at an angle relative to the axis of electrode 12.
- a recess 18 is provided in electrode 12 while electrode 16 is equipped with a tapered end portion 20.
- a refractory tube 22 is placed with one end over tapered end portion 20 which fits in the hollow tube space 24, and the other end is placed in recess 18.
- Recess wall 26 supports the tube 22 and also provides good electrical contact between the electrode 12 and tube 22.
- the electrodes 12, 16 are initially spaced a desired distance and positioned to form an angle of up to 75, usually about 55.
- Tube 22 is slipped over tapered end 20 of electrode 16 and into recess 18.
- a voltage is applied to electrodes 12, 16 and since the tube 22 electrically connects the two electrodes, at current flows through the tube walls.
- Local arcing occurs within the tube and the air dielectric is broken down with the result that an arc is struck between electrodes 12, 16 through the hollow space 24 of the tube 22.
- the tube 22 is ejected from the region of the arc by the force of the arc and expanding air.
- the refractory tube 22 is more clearly illustrated in FIGS. 2 and 3.
- the tube is provided with a relatively thin wall 28 in the preferred embodiment because electrical resistance is thereby increased and, in addition, the initial positioning of the tube is thereby facilitated.
- the wall thickness is preferably between about 4 percent to about percent of the outside diameter of the tube.
- the tube is illustrated as being cylindrical in shape, generally any shape which will provide a suitable path for the arc to be struck is acceptable.
- a tube 30 having a hollow center space 32 is also provided with 'an opening 34. The opening facilitates placement of the tube on certain electrodes, such as two tapered electrodes, and aids in the.
- a negative copper coated carbon electrode measuring A inch in diameter and 9 inches in length.
- the electrodes were present with an air gap of ,5 inch therebetween.
- a carbon tube inch long and having an inside diameter of 0.195 inch with an outside diameter of 0.242 inch was placed at one end over the tapered negative electrode and at the other end on the lower wall of the positive electrode recess.
- a voltage of about 60 volts and a current of 125 amperes were applied to the electrodes and through the tube causing an arc to be struck and the tube to be automatically ejected. The voltage and current were thereafter main tained at the same level.
- EXAMPLE II Same as Example I except that the initial gap between electrodes was inch, and the voltage applied was volts with a current of amperes.
- EXAMPLE III A positive copper coated carbon electrode measuring 9 millimeters in diameter and 14 inches long was set at an angle of 0 relative to a negative copper coated carbon electrode 8 millimeters in diameter by 9 inches long. An arc gap of .275 inch was bridged by a carbon tube 0.195 inch inside diameter, 0.242 inch outside diameter, and inch long. An arc was struck and the tube was ejected with a voltage of 45 volts and a current of amperes which were also used tomaintain the arc.
- the tube may be composed of other refractory materials such as coke, graphite, and combinations of various forms of carbon.
- various electrode configurations embodying recesses and tapered end portions can be employed.
- an arc lamp comprising two electrodes with a gap therebetween, the improvement which comprises an electrically conductive refractory tube having a hollow center portion extending therethrough, said tube being positioned in said gap between said electrodes and being in direct contact with said electrodes, whereupon with the passage of current through said tube an arc is struck between said electrodes in said hollow portion.
- an arc lamp comprising two electrodes in a spaced relationship, one of said electrodes having a tapered end portion and the other electrode having a recessed end portion
- the improvement which comprises an annular electrically conductive refractory tube in direct contact with said electrodes, said tube having a hollow center portion and being positioned with one end in said electrode recessed portion and the other end being placed over said tapered electrode section, said tube being positioned such that upon application of electrical energy to said electrodes current passes through said tube to thereby strike an arc between said electrodes and to thereby automatically eject said tube from said electrodes.
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US76410368A | 1968-10-01 | 1968-10-01 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3521114A true US3521114A (en) | 1970-07-21 |
Family
ID=25069694
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US764103A Expired - Lifetime US3521114A (en) | 1968-10-01 | 1968-10-01 | Automatic starting arc lamp |
Country Status (1)
Country | Link |
---|---|
US (1) | US3521114A (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2607024A (en) * | 1951-01-27 | 1952-08-12 | Edward M Marwell | Automatic arc starting device |
US3274427A (en) * | 1965-03-15 | 1966-09-20 | Pek Labs Inc | Self-starting arc lamp |
US3452236A (en) * | 1966-12-06 | 1969-06-24 | Westinghouse Electric Corp | High-pressure electric discharge lamp having magnetically actuable arc ignition means,and apparatus for starting such a lamp |
-
1968
- 1968-10-01 US US764103A patent/US3521114A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2607024A (en) * | 1951-01-27 | 1952-08-12 | Edward M Marwell | Automatic arc starting device |
US3274427A (en) * | 1965-03-15 | 1966-09-20 | Pek Labs Inc | Self-starting arc lamp |
US3452236A (en) * | 1966-12-06 | 1969-06-24 | Westinghouse Electric Corp | High-pressure electric discharge lamp having magnetically actuable arc ignition means,and apparatus for starting such a lamp |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: MORGAN GUARANTY TRUST COMPANY OF NEW YORK, AND MOR Free format text: MORTGAGE;ASSIGNORS:UNION CARBIDE CORPORATION, A CORP.,;STP CORPORATION, A CORP. OF DE.,;UNION CARBIDE AGRICULTURAL PRODUCTS CO., INC., A CORP. OF PA.,;AND OTHERS;REEL/FRAME:004547/0001 Effective date: 19860106 |
|
AS | Assignment |
Owner name: UNION CARBIDE CORPORATION, Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:MORGAN BANK (DELAWARE) AS COLLATERAL AGENT;REEL/FRAME:004665/0131 Effective date: 19860925 |
|
AS | Assignment |
Owner name: NATIONAL ELECTRICAL CARBON CORPORATION,SOUTH CAROL Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNION CARBIDE CORPORATION;REEL/FRAME:004685/0800 Effective date: 19861211 Owner name: NATIONAL ELECTRICAL CARBON CORPORATION, A DE. CORP Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNION CARBIDE CORPORATION;REEL/FRAME:004685/0800 Effective date: 19861211 |