US2116393A - Arc-back suppressor for electric discharge devices - Google Patents

Arc-back suppressor for electric discharge devices Download PDF

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Publication number
US2116393A
US2116393A US61938A US6193836A US2116393A US 2116393 A US2116393 A US 2116393A US 61938 A US61938 A US 61938A US 6193836 A US6193836 A US 6193836A US 2116393 A US2116393 A US 2116393A
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United States
Prior art keywords
anode
arc
fire
cathode
discharge
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Expired - Lifetime
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US61938A
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English (en)
Inventor
Rolland C Griffith
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General Electric Co
Original Assignee
General Electric Co
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Filing date
Publication date
Priority to NL46156D priority Critical patent/NL46156C/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US61938A priority patent/US2116393A/en
Priority to DE1937A0081727 priority patent/DE699370C/de
Application granted granted Critical
Publication of US2116393A publication Critical patent/US2116393A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/14—Magnetic means for controlling the discharge

Definitions

  • sorraasson Foa EIECTRIC mscnrmcr navrcas Schenectady, N. Y., assignor to General Electric Company, a corporation of New York A plication February 1, 19, Serial No. 61,938-
  • My invention relates to arc-back suppression ,rneans for electric discharge devices, and more particularly for such devices when used for the rectification of alternating currents.
  • Electric discharge devices employed as rectifiers are normally regarded as being unilaterally conducting; that is, they will permit a flow of current therethrough only at such times as the anode electrode is positive with respect to the cathode.
  • FIG. 1 shows in partial section a schematic drawing of an electric discharge device embodying my invention
  • Fig. 2 shows a fragmentary portion of a similar device having associated therewith an iron magnetic structure
  • Fig. 3 is a plan view of Fig. 2
  • Fig. 4 illustrates in section a modified embodiment of the invention as applied to a pool-type discharge device
  • Fig. 5 shows a detailed perspective view of the magnetic structure of Fig. 4
  • FIG. 6 and l are fragmentary sections of possible modifications of the invention, while Figs. 8 and 9 show in vertical and horizontal sections respectively the application thereof in connection with a special arc extinguishing structure.
  • a sealed envelope I of glass or other non-metallic insulating material At its lower portion the envelope comprises a depending tubulation 2 of reduced cross-section while at the top it flares laterally into a hollow skirt structure, the outer portion of which is conformed to provide. an annular chamber 3. This is in communication throughout its circumference with the depending chamber 2 through the circumferentially extending passageway 4.
  • cathode 1 Fixed to the base of the tube are bayonet contacts 5 which are in current-conducting relation with an enclosed cathode 1 by means of lead-in conductors sealed into a suitable vpress 8. While the nature of the cathode 1 is not essential to my invention, it will be understood that it may comprise a hollow cylinder enclosing extended emission surfaces having thereon a coating of an activating material such as an alkaline earth metal oxide. Such cathodes are conventionally heated indirectly by means of a resistance wire filament arranged coaxially with the outer shield and provided with heating current through two of the bayonet contacts 5. An example of-this type of cathode is disclosed in Patent No. 1,924,318 to A. W. Hull.
  • anode I mounted within the annular chamber 3 and supported in any convenient manner I provide an anode I shown in this instance asbearing the shape of a toroid of generally rectangular cross-section and in conductive relation with the outside of the envelope l by means of a suitable lead-in conductor H. While it is preferred that the anode Ill be formed to have a substantially continuous re-entrant surface l2 for receiving a discharge, it is desirable for use in connection with my invention that it be provided at some portion of its circumference with a gap or insulating section which will minimize the free circulation of currents induced in the anode.
  • any discharge passing between the cathode I and the anode ill will be obliged to pass laterally through the passage 4.
  • I may provide an auxiliary electrode l3 mounted directly above the cathode and connected to the anode means by a resistance l4.
  • tubes of this kind are occasionally subject to the occurrence of a reverse or back-fire are between the anode and the cathode.
  • I propose to prevent such a back-fire from becoming a sustained are by assuring that throughout the period of its duration the concentrated back-fire arc stream shall be forced to move continuously around the inner surface l2 of the anode Ill. In this way it will be impossible for any small region of the anode surface to become so intensely heated as to be still capable of thermionic emission after the removal of the back-fire cause.
  • I accomplish this result by providing in the neighborhood of the anode a magnetic field producing means which will operate on the arc stream to give it rotary motion.
  • this comprises a coil l5 having its turns concentric with the single turn of the anode l0.
  • the direction of current flow in the coil to be that indicated by the small arrow appearing at the extreme left of the drawings, it is clear that a magnetic field will be created through the coil l 6 in the direction indicated by the aligned arrows.
  • the magnetic circuit includes an iron core having an extended flux gap paralleling the inner surface ofthe anode and including within its field the region adjacent the anode.
  • the core comprises a horseshoe portion I9 whose pole tips are provided with annular extensions 20 and 2i arranged on opposite sides of the transverse passageway
  • the magnetic circuit is excited by means of a coil 22 wound on one leg thereof and acts to conserve and concentrate the lines of magnetic force in the region where they will be most effective in producing displacement of the arc stream.
  • the core pieces are comprised of laminations which lie insofar as possible parallel to the direction of magnetic flux.
  • the field-producing means may be maintained inoperative during the normal operation of the discharge device, or more precisely during the forward conducting period of the discharge path comprising the particular anode involved in the back-fire occurrence.
  • the energizing circuit for the "coil 22 includes a battery 23 of suitable capacity and a three-electrode thermionic discharge device 24 of a type which is non-conductive as long as its grid element is maintained at In the present instance the to. the tube cathode by being connected through the resistor 21 to the negative terminal of the biasing battery 26. A fixed potential relationship is maintained between the grid and cathode electrodes by means of the potentiometer connection 28.
  • the polarized relay 29 which has an energizing coil 29' in series with the main anode circuit and is of such nature as to be held open except on occasions of reverse current flow, is immediately picked up and complews a circuit through the contacts 30.
  • the relay 29 should be adapted for extremely high speed operation and should therefore be provided with moving parts of very low inertia. For this reason instead of using a mechanical switch of the type illustrated, it may in some cases'be desirable to substitute a thermionic discharge device, such as a controlled vacuum tube.
  • the closure of the contacts 30 immediately connects the grid directly to the positive terminal of the biasing battery and renders the tube 24 instantaneously conductive.
  • the exciting coil 22 is energized by current drawn from the battery 23 and sets up a magnetic fiux through the iron core l9.
  • a relay circuit such as that described it is somewhat difficult to cause the magnetic field to build up with sufficient rapidity to assure the desired rotation of the back-fire arc during the first half cycle of its occurrence.
  • the arc is repeated on subsequent half cycles it will be rotated in the manner described above and its prompt extinction ensured.
  • I provide in series with the coil 22 a delayed action relay comprising a coil 3
  • and the inertia of the mechanical parts associated therewith are sufllciently great so that operation of the switch arm 33 will be delayed for one or more half cycles.
  • FIG. 4 I have shown a. slightly modified embodiment of my invention as used in connection with a discharge tube having a pool-type cathode 35.
  • this comprises a body of mercury or other readily vaporizable metal collected at the bottom of the envelope 36 and connected to the exterior thereof by means of a suitable lead-in connection 31.
  • auxiliary starting electrode such as that shown at 38.
  • This may comprise, for example, a pointed body of some conducting material, such as boron carbide dispersed in clay, projecting into the mercury and supported and energized by means of a heavy lead-in conductor 39.
  • the envelope is formed as a smooth glass cylinder without the laterally projecting aprons described in connection with Figs. 1 and 2.
  • the envelope is provided at the top thereof with a re-entrant depending portion 40 which is encircled by an annular anode 4
  • the magnetic structure which is illustrated more completely in Fig. 5, comprises a frame 42 including a stack of three-legged laminations of which the central element 43 terminates in a solid cylindrical portion 44, the outer legs 45 and 46 being symmetrically connected to a stack of annular laminations 41.
  • Fig. 6 I have illustrated a construction by means of which my invention may be applied to a rectifier comprising a perfectly smooth'cylindrical envelope 49.
  • the electrode structure illustrated comprises a thermionic cathode 50 and an inverted cup-shaped anode 5
  • Fig. '7 shows a further simplified construction in which means are provided for assuring that the direction of flow of the discharge current in the region closest to the anode will be transverse to the magnetic field created by the coil 54'.
  • the envelope 55 is shown as enclosing a thermionic cathode 56 and a solid cylindrical anode 51 supported from the top of the envelope.
  • I provide a conical baifle member 58 of suitable refractory insulating material such as magnesium oxide or lava.
  • this last-named element is to cause the discharge stream proceeding from the cathode 56 to be diverted first outwardly toward the walls of the envelope 55 and, after passing the upper edges of the baffle 53, inwardly to the circumferential surface of the anode 51. Since the magnetic field of the coil 54 is necessarily in a vertical direction, it will be clear that the required electromagnetic reaction will be produced to assure the desired movement of the are stream.
  • Figs. 8 and 9 I have illustrated the use of my invention in connection with a special structure adapted to insure the immediate extinction cf backfire arc during the first half cycle of its duration.
  • this construction is similar to that already described in connection with Fig. 2. It comprises an envelope 6
  • an iron magnetic structure comprising a core 64 terminating'in a pair of. extended annular pole pieces 55 and 6B.
  • baflies 'Il are of conducting material and are each provided with a gap to permit the passage of a discharge therethrough.
  • the gaps may be variously associated but are shown in this particular instance as being dimensioned so that as one proceeds from the anode to the cathode each gap subtends a radial angle greater than that subtended by the preceding bafiie.
  • sectionalization of an arc in this manner has a very strong tendency to extinguish the same both by elongation of the arc stream and by the socalled dc-ion effect. Consequently the construction described operates not only to prevent the are from becoming stationary on a particular portion of the anode surface at any time during its existence but also acts to shorten appreciably the actual are life.
  • a cathode In an electric discharge device subject to back-fire, a cathode, an anode having a substantially continuous re-entrant surface for receiving a discharge, and means operable during the occurrence of a back-fire arc to produce a magnetic field parallel to said surface, said means comprising a pair of. superposed diiferentially connected coils concentric with said anode and having their intermediate plane substantially in the plane of said surface.
  • a cathode In an electric discharge device subject to back-fire, a cathode, an anode having a substantially continuous re-entrant surface adapted to receive a discharge from said cathode, means comprising a plurality of spaced conducting baffles successively interposed between said cathode and anode, a magnetic structure adjacent to said anode having a major flux path parallel to the re-entrant surface thereof, and means operable to excite said magnetic structure during the occurrence of a backfire are thereby to move said are into position to be sectionalized by said bafiles.
  • a cathode a toroidal anode adapted to receive a discharge from said anode, a plurality of spaced annular baffles successively interposed between said anode and cathode, but each having a gap therein for passage of a discharge, a magnetic structure adjacent to said anode and having a major flux path transverse to the direction of. discharge flow, and means operable to excite said magnetic structure during the occurrence of a back-fire are through said gaps thereby to move said are into position to'be sectionalized by said bailies.
  • a discharge path comprising a cathode and an anode, and means effective during a back-fire occurrence to produce continuous motion of the back-fire arc over the anode surface, said means being inoperative during the forward conducting period of said discharge path.
  • a discharge path comprising a cathode and anode, and means including a magnetic field-producing element adjacent said anode effective during a back-fire occurrence to cause continuous motion of the back-fire arc'over the surface of said anode, said means being inoperative during the forward conducting period of said discharge path.
  • a cathode, an anode, and a magnetic structure adjacent said anode for producing continuous rotary motion of a back-fire are over the surface of said anode,'said structure being energized only during the occurrence of a back-fire arc.
  • An electric rectifier comprising arc-supporting electrodes, one of said electrodes being intended to function normally as anode but being subject to temporary undesired functioning as cathode for a back-fire are by the formation of a cathode spot thereon, and means for setting up by the current supporting such reverse are a magnetic field effective to move the position of said cathode spot over the surface of the anode. said means being inoperative during the normal forward conducting period of said rectifier.
  • an envelope enclosing a cathode and a major axis of the envelope, said anode having a substantially continuous reentrant surface for receiving a discharge proceeding in a direction transverse to said axis, means forconflning a discharge to said surface, a magnetic structure mounted adjacent said anode and having a flux path parallel to said surface and an exciting winding for said magnetic structure adapted to be energized during the occurrence of a back-fire are thereby to produce a continuous motion of the m arc over said surface.

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  • Electron Sources, Ion Sources (AREA)
  • Arc-Extinguishing Devices That Are Switches (AREA)
US61938A 1936-02-01 1936-02-01 Arc-back suppressor for electric discharge devices Expired - Lifetime US2116393A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL46156D NL46156C (de) 1936-02-01
US61938A US2116393A (en) 1936-02-01 1936-02-01 Arc-back suppressor for electric discharge devices
DE1937A0081727 DE699370C (de) 1936-02-01 1937-01-20 Elektrisches Entladungsgefaess mit Einrichtung zur Verhinderung der schaedlichen Auswirkung von Rueckzuendungen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US61938A US2116393A (en) 1936-02-01 1936-02-01 Arc-back suppressor for electric discharge devices

Publications (1)

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US2116393A true US2116393A (en) 1938-05-03

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DE (1) DE699370C (de)
NL (1) NL46156C (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2490542A (en) * 1944-01-14 1949-12-06 Gen Electric Mercury arc rectifier
US2543702A (en) * 1941-04-11 1951-02-27 Hartford Nat Bank & Trust Co Magnetic field controlled gas filled discharge device
US2700122A (en) * 1950-01-21 1955-01-18 William C Milligan Electronic tube
US3229155A (en) * 1960-12-20 1966-01-11 William C A Carlson Electric arc device for heating gases
US3259792A (en) * 1962-12-31 1966-07-05 Ite Circuit Breaker Ltd High voltage spark gap

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543702A (en) * 1941-04-11 1951-02-27 Hartford Nat Bank & Trust Co Magnetic field controlled gas filled discharge device
US2490542A (en) * 1944-01-14 1949-12-06 Gen Electric Mercury arc rectifier
US2700122A (en) * 1950-01-21 1955-01-18 William C Milligan Electronic tube
US3229155A (en) * 1960-12-20 1966-01-11 William C A Carlson Electric arc device for heating gases
US3259792A (en) * 1962-12-31 1966-07-05 Ite Circuit Breaker Ltd High voltage spark gap

Also Published As

Publication number Publication date
DE699370C (de) 1940-11-27
NL46156C (de)

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