US3543075A - Three-electrode spark gap device for switching high current intensities under high voltage - Google Patents

Three-electrode spark gap device for switching high current intensities under high voltage Download PDF

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Publication number
US3543075A
US3543075A US739715A US3543075DA US3543075A US 3543075 A US3543075 A US 3543075A US 739715 A US739715 A US 739715A US 3543075D A US3543075D A US 3543075DA US 3543075 A US3543075 A US 3543075A
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spark gap
gap device
cathode
anode
electrode
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US739715A
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English (en)
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Jean Claude Dubois
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IFP Energies Nouvelles IFPEN
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IFP Energies Nouvelles IFPEN
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T2/00—Spark gaps comprising auxiliary triggering means
    • H01T2/02—Spark gaps comprising auxiliary triggering means comprising a trigger electrode or an auxiliary spark gap

Definitions

  • a three-electrode spark gap device for closing a circuit which is connected with a very high voltage electric generator and in which a very high intensity is established.
  • the spark gap device comprises a cylindrical anode electrically connected to a terminal of the generator, a cathode having shape of a cylindrical ring surrounding and coaxial with the anode.
  • the cathode includes on its internal wall radial extensions formed of partitions each terminated by a plate.
  • the spark gap device also includes at least one striking electrode located in the space limited bv the two radial planes passing along the edges of two consecutive plates and by the annular segment of the cathode between these plates.
  • the striking electrode being more particularly located in the space limited by the annular segment, the radial planes and the plates and being connected with a generator providing a shock voltage.
  • the switched voltage is applied between two electrodes (anode and cathode), called main electrodes, which have such a spacing that the field prevailing between these electrodes is lower than the disruptive level, so that no spark is produced between these electrodes.
  • a third electrode, called striking electrode, located in the vicinity of one of the main electrodes is supplied with a high voltage. This high voltage strikes between this third electrode and either the two main electrodes a spark which generates an ionized cloud lowering the disruptive level, i.e. the critical threshold under which no spark is produced, thereby allowing the electric discharge to build up between anode and cathode.
  • Electrodes either of hemispherical shape, or constituted of plane plates, or also of stackings of plates. 2
  • spark gap devices do not exhibit a structure which is strong enough to withstand the very high current intensities flowing through the device.
  • the object of the present invention is to realize a new three-electrode spark gap device for switching very high current intensities under high voltage, such conditions being for example encountered during the operation of a seismic sparker.
  • This spark gap device has a strong structure, provid ing broad electrode areas, a good thermal dissipation 3,543,075 Patented Nov. 24, 1970 and a good mechanical resistance to the acoustical shock Wave generated at the instant of striking.
  • Such a spark gap device has a coaxial structure. Its anode is a smooth metallic cylinder located within the cathode. The latter has the shape of a hollow cylinder, the annular internal wall of which has radial extensions along generatrices of the cylinder.
  • the striking electrodes are constituted by rods located in the intervals separating the radial extensions of the cathode, each electrode having its own energizing circuit.
  • the spacing between anode and cathode will preferably be higher than 1.5 times the disruptive distance.
  • FIG. 1 diagrammatically shows a three-electrode spark gap device combined with an electric circuit.
  • FIG. 2 diagrammatically shows a perspective view of a spark gap device according to the invention.
  • FIG. 3 is a view of the spark gap device shown by FIG. 2, together with its energizing device.
  • FIG. 4 illustrates a longitudinal sectional view of a part of the device of FIG. 3, provided with a three-stage anode.
  • FIG. 1 showing the general diagram of a circuit for energizing a three-electrode spark gap device
  • a circuit for energizing a three-electrode spark gap device such a circuit includes a high voltage generator G connected with a condenser C, a resistance R, a three-electrode spark gap device E, the two main electrodes of which p and 1 are supplied with high voltage by the condenser C, and the striking electrode a is supplied with a shock voltage emanating from a source I.
  • the spark gap device E controls the operation of an electrical apparatus A, which may be for example a seismic sparker.
  • the electrodes p and p are spaced by a distance which is slightly higher than the spacing creating the disruption, so that no spark is directly generated between these electrodes.
  • this device includes in particular an anode 1 which is a cylinder made of a metal having a good electrical conductivity.
  • Its cylindrical wall is plated with a metal having a high melting-point, such as for example tungsten.
  • the cathode 3 has the shape of a cylindrical ring 4 having substantially the same length as the anode which it surrounds, being coaxial with this anode.
  • This cathode is provided with radial extensions on its internal wall, located at regular intervals. These extensions are constituted by partitions 5 secured to the cylindrical ring 4 along generatrices thereof, each of which being provided with a plate 6 at its end.
  • the internal surface of these plates is incurved so as to constitute a portion of a cylinder centered on the axis of symmetry of the system.
  • the spacing between these plates is substantially equal to their width.
  • This surface is coated with a refractory metal, for example with tungsten.
  • the cathode as a whole is made of a metal which is a good conductor of electricity.
  • the striking or control electrodes 2 are constituted by tungsten rods having a diameter between 2 and 3 mm.
  • each of them is located in the space limited by two radial planes containing the edge 6a of two consecutive plates, on the one hand, and the annular segments of the cathode located between said radial planes, on the other hand. More particularly, those striking electrodes will be located in the space limited by these annular segments, said radial planes and the plates 6, and located along generatrices of a cylinder the axis of which is that of the device.
  • the electrical connection of the anode is made along the axis of this electrode by means of a cable 7 (FIG. 3) connected with one of the terminals of a capacity (not shown) charged under a very high voltage.
  • the electrical connection of the cathode is made by means of a shell 8 having a cylindrical internal wall in contact with the external wall of the cathode.
  • This shell is made of a metal which is a good conductor of electricity and is thick enough to provide for a good distribution of the lines of current leaving the connecting cable all around the cathode.
  • a cable 9 connects this shell with the other terminal of the capacity.
  • the rods 2 which constitute the striking electrodes are carried by two discs 10 made of an insulating material, located on both sides of the spark gap device and maintained spaced by means of cross members.
  • Each of the electrodes 2 is connected with a cable 11 which supplies it with a very high intensity
  • the anode 1 is carried by a shaft 12, each end of which is secured to an insulating support member 13.
  • the cathode 3 is carried by the shell 8, which is itself secured to insulating support members 14.
  • the insulating discs 10 carrying the striking electrodes 2 are centered on the shaft 12 of the anode.
  • the supply voltage is applied between the anode 1 and the cathode 3 of the spark gap device at the instant of the sudden discharge of a condenser through the cables 7 and 9.
  • All the striking electrodes 2 are excited separately and in synchronism by a shock voltage through the cable 11.
  • a pilot spark is then generated at the level of each striking electrode, between this electrode and the anode or the cathode, each spark ionizing the space where it is produced.
  • These different ionization points produce a local decrease in the disruptive potential and an arc is thus created between the plate 6 of each sector of the cathode 3 and the anode 1.
  • the are is interrupted when the voltage falls below the de-energization voltage which is very low, i.e. at the end of the discharge of the condenser.
  • the anode 1 is constituted by a cylinder provided with several stages 1a, 1b, 10, having different diameters, this cylinder being slidable along the shaft 12 by means of a lever 15, whereby its position on this shaft can be located for example by means of a pawl and ratchet mechanism.
  • the length of each stage substantially corresponds to the length of the segments of the cathode.
  • the zones of connection between the different stages will advantageously have a conical shape, generally without marked edges, so as to prevent too sudden a striking of the spark at the passage from a stage to another.
  • Each stage corresponds to a different distance between anode and cathode (distance d d d FIG. 4) and thus to a different range of voltages of utilization the smallest distance between anode and cathode corresponding to the passage of the lowest voltages.
  • Such a device provides for easy switching in the range of the voltages of operation of the spark gap device. It is also possible to provide the device according to the invention with an ultra-violet lighting of the space between the electrodes in order to increase the stability of this device control.
  • spark gap device in a container filled with an inert gas under pressure.
  • the plurality of striking points is favourable to the development of an ionized annular zone.
  • the internal partitioning of the cathode increases the stability of the discharge, by decreasing the effect of selfblowing out of the arc and of rotation of the lines of currents. It results thereform a lowering of the de-energization voltage.
  • coaxial conductors It is known that in the field of the hyperfrequences, it is preferable to use coaxial conductors.
  • the coaxial struc ture according to the invention is thus also favourable to high frequency switch.
  • the voltage of operation of this spark gap device can be adapted within a very broad range (up to 50 kv.), it is suflicient for this purpose to vary the diameter of the anode cylinder.
  • Three-electrode spark gap device for closing a circuit which is connected with a very high voltage electric generator and in which a very high intensity is established, said spark gap device including a cylindrical anode electrically connected with a first terminal of the generator, a cathode having the shape of a cylindrical ring surrounding said anode and coaxial therewith, said cathode including on its internal wall, along its generatrices, radial extensions formed of partitions each terminated by a plate, said spark gap device also including a striking electrode located in the space limited on the one hand by two radial planes passing along the edges of two consecutive plates and, on the other hand, by the annular segment of the cathode comprised between these planes, said striking electrode being more particularly located in the space limited by said annular segment, said radial planes and said plates and being connected with a generator providing a shock voltage.
  • said anode is constituted by a cylinder having a length greater than the cylinder of the cathode, said cylinder con References Cited UNITED STATES PATENTS 1/1952 Partiot 313198 X 2/1961 Coeterier 313217 X JAMES W. LAWRENCE, Primary Examiner C. R. CAMPBELL, Assistant Examiner U.S. C1.X.R.

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  • Chemical And Physical Treatments For Wood And The Like (AREA)
US739715A 1967-06-29 1968-06-25 Three-electrode spark gap device for switching high current intensities under high voltage Expired - Lifetime US3543075A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR112550 1967-06-29

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US3543075A true US3543075A (en) 1970-11-24

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US (1) US3543075A (xx)
DK (1) DK126538B (xx)
FR (1) FR1568751A (xx)
GB (1) GB1168598A (xx)
NL (1) NL159829B (xx)
NO (1) NO118859B (xx)
OA (1) OA02835A (xx)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3983438A (en) * 1975-08-21 1976-09-28 Xonics, Inc. Spark gap switch

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2581970A (en) * 1948-10-07 1952-01-08 Partiot Maurice System for controlling flow of electric currents
US2973446A (en) * 1958-12-20 1961-02-28 Philips Corp Electric discharge tube

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2581970A (en) * 1948-10-07 1952-01-08 Partiot Maurice System for controlling flow of electric currents
US2973446A (en) * 1958-12-20 1961-02-28 Philips Corp Electric discharge tube

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3983438A (en) * 1975-08-21 1976-09-28 Xonics, Inc. Spark gap switch

Also Published As

Publication number Publication date
FR1568751A (xx) 1969-05-30
DE1763559A1 (de) 1971-10-28
NL159829B (nl) 1979-03-15
DE1763559B2 (de) 1977-04-07
NL6808973A (xx) 1968-12-30
NO118859B (xx) 1970-02-23
OA02835A (fr) 1970-12-15
DK126538B (da) 1973-07-23
GB1168598A (en) 1969-10-29

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