US2276732A - Lightning arrester - Google Patents

Lightning arrester Download PDF

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Publication number
US2276732A
US2276732A US321458A US32145840A US2276732A US 2276732 A US2276732 A US 2276732A US 321458 A US321458 A US 321458A US 32145840 A US32145840 A US 32145840A US 2276732 A US2276732 A US 2276732A
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United States
Prior art keywords
silicon
particles
mesh
carbide
crystals
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Expired - Lifetime
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US321458A
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English (en)
Inventor
Leon R Ludwig
Frederick B Johnson
William E Berkey
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CBS Corp
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Westinghouse Electric and Manufacturing Co
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Priority to US321458A priority Critical patent/US2276732A/en
Priority to DES144266D priority patent/DE752247C/de
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Publication of US2276732A publication Critical patent/US2276732A/en
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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
    • H01T1/00—Details of spark gaps
    • H01T1/16—Series resistor structurally associated with spark gap

Definitions

  • Our invention relates to lightning ,arrestera and it has particular relation to lightning-arrester valve-elements utilizing silicon-carbide crystals as a basis, said crystals either being in loose form, packed between two terminal electrodes, or bound together in a solid mass, with a binder, preferably a ceramic binder.
  • the object of our invention is to improve the performance of these silicon-carbide lightningarrester valve-elements.
  • a more specific object of our invention is to provide such an arrester in which difliculties due to arrester-failure, or short life, particularly when subjected to long-tail waves, may be avoided by the admixture of suitable fine inert or relatively electrically non-conducting particles or binding material in a particle-size and quantity approximately sufllcienjt, or nearly sufilcient, to just ll the voids between the larger siliconcarbide particles which constitute the principal part of the lightning-arrester valve-element.
  • a still more specic object of our invention is to provide a ceramic molded block or lightningarrester valve-element, in which silicon-carbide crystals are held together by a relatively insulating arc-resisting binder, in the form' of clay or other ceramic binderfin quantities much smallerl than have heretofore been commonly utilized in clay-bound lightning arresters, and, in fact, in quantities so small that no substantial volumeshrinkage is encountered upon the firing of the block, in the process oi' manufacture, which means that the clay is not materially more than enough to fill the voids between the carbide crystals.
  • Figure 1 is a vertical sectional view of a lightning-arrester embodying our invention in a loosegrain form
  • Fig. 2 is a similar View illustrating an embodiment of the inventionin a ceramic-block form.
  • the conventional arrester-element utilizing silicon-carbide crystals consists of a large number of crystals, so that the circuit from one terminal-electrode to the other consists of a large number of parallel paths, each of the parallel paths consisting of a column of crystals. 'I'hese parallel paths are solidly interconnected at each end, by the arrester-terminals, and are also interconnected at intermediate points, all along their length, by incidental sideways contacts to adjacent crystals.
  • Another method of preventing or retarding the lashover of the individual crystals is to ll, or partially fill, the voids or spaces between the larger or main contact-carrying crystals with an inert or relatively high-resistance arc-resisting material which will suppress the growth of the sparks initiatingl at the crystal-junctions.
  • This void-filling material may be either finely-divided loose-material, such as silicon-carbide crystals of less than 250-mesh size, and preferably at least a neness of 325-mesh size, or even finer powders such as 60G-mesh silicon-carbide, or the void-filling material may be made from refractory, relatively insulating materials such as flint, other than silicon-carbide, although, in the loose form of silicon-carbide arrester-elements, the i fine silicon-carbide filler has so far proven to be the preferable filler-material.
  • the iineness of the 250- or B25-mesh particles makes them interpose a larger number of serially connected contacts in any given length of arrester, so that they offer a higher electrical resistance to the discharge of current through the arrester than the coarse particles, so that the arrester-current is largely carried by the larger particles which are in shunt thereto.
  • the fine-particled void-filling material may be the binding material which holds the ⁇ silicon-carbide particles together in solid form.
  • claybound crystal blocks such as were known and utilized before the water-glass-bound blocks became customary, are not suitable for our purpose because such clay-bound blocks contained a very large quantity of clay, as compared with the quantity of,y the silicon-carbide crystals, so that the silicon-carbide conducting particles were relatively far apart.
  • a lightning arrester utilizing a porcelain housing I having a lineterminal 2 entering at the top, and a. groundterminal 3 at the bottom.
  • the porcelain housing I is hollow, containing, at its lower end, a terminal-electrode 4 which is properly sealed, to the bottom of the housing, by a. sealing-gasket 5.
  • Disposed over this bottom terminal-electrode 4 is a loose mass consisting of a large number of ⁇ silicon-carbide crystals 6 mixed, in accordance with our invention, and pressed down, at the top, by a terminal-electrode or contact-plate 1.
  • the contact-plate I is surmounted by a.
  • the edges of which are spun in place against the bore of the porcelain housing I this thin metal disc 8 being strengthened or stilened by a backing-up plate 9.
  • the two plates 'I and 9, with the spun-metal disc 8 between them, are preferably riveted together, as indicated -at II.
  • the space near the bore of the porcelain housing I is further cemented by a gum seal I2 forfpreventing leakage of the fine silicon-carbide dust during shipment, when the arrester may be turned upsidedown.
  • our arrester Surmounting the valve-element part of the arrester, which is made up by the terminal platestructures 4 and 1, and the intervening mass of loose carbide crystals 6, we have shown our arrester as comprising a quench-gap portion I4, which is, in turn, surmounted by a spark-gap or switching-gap structure I5, which is, in turn,
  • the mass of loose silicon-carbidecrystals 6 which constitute the valve-element of our arrester is made up of a mixture which is composed, for the most part, of crystals of a certain mesh-rating, together with an admixture oi othercrystals of preferably (though not necessarily) at least three times as large a mesh-number.
  • the relative proportions of the coarse and fine crystals are such as, by calculation or experiment, have been found to be requisite, sothat the ne material is present in about the right amount, or approximately nearly the right amount, to ll the spaces or voids between the larger crystals.
  • all of the particles are preferably of silicon carbide.
  • An arrester of a given voltage-rating must, therefore, have approximately a certain prescribed number of serially connected crystal-contacts, regardless of the size of the crystals. lt thus follows that the overall height ⁇ of an arrester-column, having the prescribed number of crystal-contacts in series, is practically directly proportional to the crystal-size, which means that a large-grained crystal arrester of a given voltage-rating is taller, and hence more expensive, than a small-grained arrester.
  • a second disadvantage of an unnecessary increase in the sizes of the crystal-grains is that the protective ratio of the arrester is impaired by increasing 'the grain-size, this protective ratio beingthe ratio between the crest-voltage, which appears across the arrester during its rated current-discharge, and the cut-olf voltage of the arrester, or the ratio between the crest-voltage and the rated line-voltage of the arrester. It is obviously desirable that this so-called protective ratio should be as small as possible.
  • arresters of the larger grain-sizes are taller, or longer electrically, than arresters of the smaller grain-sizes, the large-grain arresters have a larger amount of the total overall voltage consumedin the internal resistance of the silicon-carbide grains or crystals, so that the crestvoltages of these arresters are somewhat increased.
  • Fig. 2 we show our invention in a form oi' embodiment in which, instead of utilizing a mass or owable quantity of loose silicon-carbide crystals 6, we utilize a block, or a plurality of blocks A26, of molded silicon-carbide crystals.
  • silicon-carbide crystals corresponding to the relatively coarser crystals which were utilized in the loose mix 5 of Fig. l, such as (iO-mesh, ⁇ iO-mesh, or G-mesh silicon-carbide crystals. without being limited, of course, to these parti-cular sizes, as we may utilize either coarser or finer-mesh particles, or mixtures of different meshes.
  • silicon-carbide crystals of a single mesh-rating such as GO-mesh or 80-mesh
  • the clay should be present in quantities not substantially greater than enough to fill these pores or voids. Practically, clay may be present in quantities varying between 30 and 40% of the total weight of the nnished molded arresterblock. ⁇ A proper amount of clay is the largest amount useable without allowing or causing the f block to shrink during iiring.
  • the silicon carbide and clay are thoroughly mixed together, with the addition of a small amount of/water, after which the mixed mass is molded into blocks and fired in a furnace in a non-oxidizing or reducing atmosphere, in accordance with a practice which is well known except for the relatively small quantity of clay which we utilize.
  • a lightning arrester made with molded valve-element blocks 26, as shown in Fig. 2, operates the same as in the case of the loosecrystal arrester of Fig. 1, the electrical conductivity through the block or blocks 26 being through the grains of the silicon carbide, and across the crystal-to-crystal contact-points, as in the loose-grain arrester, the clay binder being utilized jointly as a means for drawing the crystals together in a tightly held mass, and as a means for resisting the spread of the arcs or sparks which originate yat the crystal-junctions, so that individual crystals are not, in general, entirely enveloped in, and short-circuited by, a
  • our invention in its broader aspects, may alternatively utilize, as its principal constituent, that is, for its larger particles, av large number of "M-mesh granules of some other simi-conducting material, where M is no smaller than 40 and no largerthan 120.
  • An excess-voltage protective device comprising two spaced terminal-electrodes and a valve-element means bridging the space between said terminal-electrodes, characterized by said valve-element means comprising a large number of silicon-carbide granules which are for the most part of one size-range of a larger size than 10U-mesh granules, and a smaller quantity, by volume, of smaller-sized particles disposed in the spaces between said rst-mentioned granules, said smaller-sized particles being smaller than the spaces between said first-mentioned granules and offering relatively a considerable resistance to the passage of current therethrough, characterized by said smaller-sized particles being of such small size and of roughly the approximate quantity nearly sufficient to ll the voids in the coarser material.
  • An excess-voltage protective device comprising, in combination, an insulating vessel having two spaced terminal-electrodes associated therewith,C and a iiowable quantity of loose particulate matter disposed within said vessel in the space between said terminal-electrodes, said loose particulate matter comprising graded sizes of granules consisting mainly of silicon-carbide, a major portion of the silicon-carbide granules, by weight, being for the most part of one size-range, the remainder of the silicon-carbide granules' being of a considerably smaller size-range and being of such small size and of roughly the approximate quantity nearly sufficient to ll the voids in the coarser material.
  • An excess-voltage protective device comprising, in combination, an insulating vessel having two spaced terminal-electrodes associated therewith, and a flowable quantity of loose particulate matter disposed within said vessel in the space between said terminal-electrodes, said loose particulate matter comprising graded sizes of granules consisting mainly of silicon-carbide, having such relative proportions of relatively large and small particles that the smaller particles are of such small size and of roughly the approximate quantity nearly suflicient to ll the voids in the coarser material.
  • An excess-voltage protective device comprising, in combination, an insulating vessel having two spaced terminal-electrodes associated therewith, and a flowable quantity of loose particulate matter disposed within said vessel in the space between said terminal-electrodes, said loose particulate matter comprising graded sizes of granules consisting mainly of silicon-carbide, having a material proportion, by volume, of the particles at least as large as Sil-mesh, and another material, but smaller, proportion, by volume, of the particles at least as small as 250- mesh; the two groups of large and small particles, at least as large as BO-mesh, and at least as small as 250-mesh, respectively, together constituting a major portion of the loose particulate matter, the aforesaid small particles being present in roughly the approximate quantity necessary to approximately ll the voids between the aforesaid large particles.
  • An excess-voltage protective device comprising, in combination, an insulating vessel having two spaced terminal-electrodes associated therewith, and a flowable quantity of loose particulate matter disposed within said vessel in the space between said terminal-electrodes, said loose particulate matter comprising graded sizes of poorly conducting granules, a major portion of said granules, by weight, being for the most part of one size-range, the remainder of said granules being of a considerably smaller size-range and being of such small size and of roughly the approximate quantity nearly suiilcient to lill the voids in the coarser material.
  • An excess-voltage protective device comprising, in combination, an insulating vessel having two spaced terminal-electrodes associated therewith, and a flowable quantity of loose particulate matter disposed Within said vessel in the space between said terminal-electrodes, said loose particulate matter comprising graded sizes of poorly conducting granules having such relative propor. tions of relatively large and small particles that the smaller particles are of such small size and of roughly the approximate quantity nearly sufcient to lill the voids in the coarser material.
  • An excess-voltage protective device comprising, in combination, an insulating vessell having two spaced terminal-electrodes associated therewith, and a flowable quantity of loose particulate matter disposed within said vessel in the space between said terminal-electrodes, said loose particulate matter comprising graded sizes of poorly valve-element means bridging the space between -said terminal-electrodes, characterized by said valve-element means comprising at least one ilred ceramic block comprising a large number of silicon-carbide granules which are ⁇ for the most part of one size-range,/and a ceramic binder, the silicon-carbide granules including a majority of its total mass in particles at least as large as 80-mesh, and the quantity of ceramic binder beingapproximately the largest amount Y which can be utilized without causing the block conducting granules having a material proportion, by volume, of the particles at least as large as BO-mesh, and another material, but smaller,
  • An excess-voltage protective device comprising two spaced terminal-electrodes and a valveelement means bridging the space between said terminal-electrodes, characterized by said valveelement means comprising at least one moldedcomposition block comprising a large number of silicon-carbide granules which are for the most of one size-range, and a ceramic binder, the quantity of ceramic binder being sufficient to hold the block together but not substantially greater than enough to ll the voids between the silicon-carbide granules.
  • An excess-voltage protective device comprising two spaced terminal-electrodes and a valve-element means bridging the space between said terminal-electrodes, characterized by said valve-element means comprising at least one red ceramic block comprising a large number of silicon-carbide granules which are for the most part of one size-range, and a ceramic binder, the quantity of ceramic binder being approximately the largest amount which can be utilized to appreciably shrink during iiring.
  • An excess-voltage protective device comprising, in combination, an insulating vessel having two spaced terminal-electrodes associated therewith, and a flowable quantity of loose particulate matter disposed Within said vessel in the space between said terminal-electrodes, said loose particulate matter comprising graded sizes of granules, a major portion of the granules, by weight,l being M-mesh granules of semi-conducting material, where M is no smaller than 40 and no larger than 120, the remainder 'of the granules being of such small size and of roughly, the approximate quantity nearly suiiicient to lill the voids in thefcoarser material, said smaller-sized granules oiering relatively a considerable resistance to the passage of current therethrough.
  • An excess-voltage protective device comprising two spaced terminal-electrodes and a valve-element means bridging the space between l said terminal-electrodes, characterized by said valve-element means comprising at least one molded-composition block comprising, as its principal constituent, a large number of M-mesh granules of semi-conducting material, whe/re M is no smaller than 40 and no larger than 120, and a ceramic binder, the quantity of ceramic binder f being sufficient to hold the block together but not without causing the block to appreciably shrink but not substantially greater than enough to iill the voids between the silicon-carbide granules.
  • An excess-voltage protective device comprising two spaced ⁇ terminal-electrodes and a substantially greater than enough to iill the voids between the granules.
  • An excess-voltage protective device comprising two spaced terminal-electrodes and a valve-element means bridging the space between said terminal-electrodes, characterized by said valve-element means comprising graded sizes of poorly conducting granules having a material proportion, by volume, of the particles at least as large as SO-mesh, and another material, but smaller, proportion, by volume, of the particles at least as small as Z50-mesh; the two groups oi large and small particles, at least as large as mesh, and at least as small as 25o-mesh, respectively, together constituting a major portion oi the valve-element means, the aforesaid small particles being present in roughly the approximate quantity necessary to approximately iill the voids between the aforesaid large particles.
  • valve-element means comprising graded sizes of granules consisting mainly of silicon-carbide, having a material proportion, by volume, of the particles at least as large as 80-mesh, and another material, but smaller, proportion', by Volume, of the particles at least as small as 250- rnesh; the two groups of large and small particles, at least as large as Sil-mesh, and at least as small as Z50-mesh, respectively, together constituting ainajor portion of 'the valve-element means, the aforesaid small particles being present in roughly the approximate quantity necessary to approximately ll the voids between the aforesaid large particles.
  • An excess-voltage protective device comprising two spaced terminal-electrodes and a valve-element means bridging the space between said terminal-electrodes, characterized by said valve-element means comprising graded sizes of poorly conducting granules having a material proportion, by volume, of the particles at least as large as 80-mesh, and another material, but smaller, proportion, by volume, of the particles at least as small as 250-mesh, characterized by said smaller-sized particles being of such small size and of roughly the approximate quantity nearly suflicient to ll the voids in the coarser ⁇ material.
  • a excess-voltage protective device comprising two spaced terminal-electrodes and a valve-element means bridging the space between said terminal-electrodes, characterized by said valve-element means comprising graded sizes of granules consisting mainly of silicon-carbide, having a material proportion, by volume, of the particles at least as large as SO-mesh, and another material, but smaller, proportion, by volume, of the particles at least as small as 250- mesh, characterized by said smaller-sized particles being of such small size and of roughly the approximate quantity nearly suflicient to fill the voids in the coarser material.
  • An excess-voltage protective device comprisng two spaced terminal-electrodes and a valve-element means bridging the space between said terminal-electrodes, characterized by said valve-element means comprising graded sizes of poorly ,conducting granules having a material proportion, by volume, of the particles at least as large as -mesh, and another material, but smaller, proportion, by volume, of the particles at least as small as 250mesh, characterized by said smaller-sized particles including a ceramic binder which holds the valve-element means together in one or more solid masses, said smallersized particles being of such small size and of roughly the approximate quantity nearly sufficient to ll the voids in the coarser material.
  • An excess-voltage protective device comprising two spaced terminal-electrodes and a valve-element means bridging the space between said terminal-electrodes, characterized by said valve-element means comprising graded sizes of granules consisting mainly of silicon-carbide, having a material proportion, by volume, of the particles at least as large as 80-mesh, and another material, but smaller, proportion, by volume, of the particles at least as small as 250- mesh, characterized by said smaller-sized particles including a ceramic binder which holds the valve-element means together in one or more solid masses, said smaller-sized particles being of such small size and of roughly the approximate quantity nearly suflicient to fill the voids in the coarser material.

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US321458A 1940-02-29 1940-02-29 Lightning arrester Expired - Lifetime US2276732A (en)

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US321458A US2276732A (en) 1940-02-29 1940-02-29 Lightning arrester
DES144266D DE752247C (de) 1940-02-29 1941-03-01 UEberspannungsableiter mit spannungsabhaengig stromdurchlaessigem Widerstandsblock aus Siliciumkarbid

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2589157A (en) * 1949-04-29 1952-03-11 Asea Ab Voltage-dependent resistance blocks
US3040282A (en) * 1959-06-25 1962-06-19 Ohio Brass Co Valve resistors
US3066180A (en) * 1957-04-06 1962-11-27 Asea Ab Coating for equalizing the potential gradient along the surface of an electric insulation
US3096496A (en) * 1961-05-11 1963-07-02 Mc Graw Edison Co Overvoltage protective device
US3162831A (en) * 1961-09-07 1964-12-22 Ohio Brass Co Electrical valve resistor
US3955170A (en) * 1974-11-29 1976-05-04 Texas Instruments Incorporated Solid state switch
US4365282A (en) * 1980-02-14 1982-12-21 The United States Of America As Represented By The United States Department Of Energy Overvoltage protector using varistor initiated arc
US4940961A (en) * 1987-12-30 1990-07-10 Societe Anonyme Dite : Alsthom Braking resistor for a high tension electrical network
US5497138A (en) * 1992-11-27 1996-03-05 Soule Varistor surge arrestors, in particular for high tension
EP4443676A1 (de) * 2023-04-06 2024-10-09 OBO Bettermann Hungary Kft. Überspannungsableiter

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1111274B (de) * 1959-02-13 1961-07-20 Janos Kemeny Spannungsabhaengiger Widerstand und Verfahren und Vorrichtung zu seiner Herstellung

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR658305A (fr) * 1927-06-13 1929-06-03 Thomson Houston Comp Francaise Perfectionnements aux matières à conductibilité variable et aux appareils les utilisant

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2589157A (en) * 1949-04-29 1952-03-11 Asea Ab Voltage-dependent resistance blocks
US3066180A (en) * 1957-04-06 1962-11-27 Asea Ab Coating for equalizing the potential gradient along the surface of an electric insulation
US3040282A (en) * 1959-06-25 1962-06-19 Ohio Brass Co Valve resistors
US3096496A (en) * 1961-05-11 1963-07-02 Mc Graw Edison Co Overvoltage protective device
US3162831A (en) * 1961-09-07 1964-12-22 Ohio Brass Co Electrical valve resistor
US3955170A (en) * 1974-11-29 1976-05-04 Texas Instruments Incorporated Solid state switch
US4365282A (en) * 1980-02-14 1982-12-21 The United States Of America As Represented By The United States Department Of Energy Overvoltage protector using varistor initiated arc
US4940961A (en) * 1987-12-30 1990-07-10 Societe Anonyme Dite : Alsthom Braking resistor for a high tension electrical network
US5497138A (en) * 1992-11-27 1996-03-05 Soule Varistor surge arrestors, in particular for high tension
EP4443676A1 (de) * 2023-04-06 2024-10-09 OBO Bettermann Hungary Kft. Überspannungsableiter

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Publication number Publication date
DE752247C (de) 1953-09-07

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