US3377503A - Lightning arrester gap and grading means - Google Patents

Lightning arrester gap and grading means Download PDF

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Publication number
US3377503A
US3377503A US492087A US49208765A US3377503A US 3377503 A US3377503 A US 3377503A US 492087 A US492087 A US 492087A US 49208765 A US49208765 A US 49208765A US 3377503 A US3377503 A US 3377503A
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United States
Prior art keywords
gap
voltage
resistor
grading
electrodes
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Expired - Lifetime
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US492087A
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English (en)
Inventor
Joseph C Osterhout
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Westinghouse Electric Corp
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Westinghouse Electric Corp
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Priority to US492087A priority Critical patent/US3377503A/en
Priority to DE19661563924 priority patent/DE1563924A1/de
Priority to AT802866A priority patent/AT266967B/de
Priority to CH1392366A priority patent/CH446501A/de
Priority to JP41064726A priority patent/JPS5218384B1/ja
Application granted granted Critical
Publication of US3377503A publication Critical patent/US3377503A/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
    • H01T4/00—Overvoltage arresters using spark gaps
    • H01T4/16—Overvoltage arresters using spark gaps having a plurality of gaps arranged in series
    • H01T4/18—Arrangements for reducing height of stacked spark gaps
    • 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
    • H01T4/00—Overvoltage arresters using spark gaps
    • H01T4/16—Overvoltage arresters using spark gaps having a plurality of gaps arranged in series
    • H01T4/20—Arrangements for improving potential distribution

Definitions

  • the invention comprises a plurality of voltage grading variable impedance, preionizing gap means connected across the main spark gaps in a lightning arrester unit and in parallel with a second plurality of voltage grading means of equal impedance values connected across the main gaps.
  • Such a combination of means provides both balanced and unbalanced voltage grading for the arrester unit so that the voltage and resulting stresses on the unit are distributed equally throughout the unit until the moment of sparkover at which time the voltages across the gaps are unequal with a resulting overall, lower and more consistent sparkover voltage for more rapid discharge of surge current.
  • the present invention relates to valve type lightning arresters and particularly to a novel means for pre-ionizing and voltage grading lightning arrester sparkover gaps.
  • valve type arresters consist of a spark gap, or a series of spark gaps of fixed lengths, connected in series With a resistance element having valve or nonlinear characteristics, that is, a resistor whose resistance decreases with increasing voltage, so that under normal voltage (operating) conditions it offers a very high resistance and at overvoltage (abnormal) conditions it offers a low resistance so as to conduct a current surge to ground with a low discharging voltage. After the discharge of the current surge, the resistance element increases its resistance to reduce the follow current at normal voltages to a small value.
  • the series gap device normally insulates the power line to which it is connected, from ground but sparks over under a predetermined overvoltage to connect the line to ground. After the discharge to ground, the series gap acts im-. mediately to open the closed (sparkover) path to prevent the current normally flowing in the line from following in the path of the surge current.
  • Power line voltage can be evently distributed across the series gaps, with a consequent even distribution of stress, by use of an equal value shunting resistor across each gap acting as a voltage divider from line to ground.
  • shunting resistor across each gap acting as a voltage divider from line to ground.
  • One method of obtaining low, consistent gap sparkover is by pre-ionizing the spark gap area.
  • slowly raised continuous or alternating voltage will usually produce sparkovers at relatively consistent voltages, but on rapidly applied voltages, the spark potentials vary more.
  • a gap subjected to an impulse voltage may break down if the peak voltage reaches the DC. breakdown value provided that the gap is sufficiently irradiated so that an electron is present in the gap to initiate the spark process when the peak voltage is reached.
  • An electron obtained by the process of ionization is thus required to consistently initiate the spark discharge. Sparkover occurs at consistent values with slowly increased voltages such as direct current or 60 cycle A.C.
  • sparkover voltage remains because ions usually have time to appear. With rapidly rising impulse voltages, ions may not have time to collect in the spark gap area. Thus the voltage will us until ions do appear or until the voltage produces them. Therefore, means should be provided in the spark gap area to insure a sufiicient supply of ions in order to maintain a low, consistent impulse voltage sparkover level.
  • the present invention provides a pre-ionizing means for series gap valve-type arresters presently in production.
  • the operation and structure of one such type of arrester is fully shown and described in copending application Ser. No. 405,945, filed Oct. 23, 1964, by Joseph C. Osterhout, and assigned to the present assignee.
  • Such arresters have limited space available in the arc chamber and in the area of the spark gap electrodes. Therefore in designing a pre-ionizer means for such arresters, space is an important consideration. Production cost and skills, manufacturing ease and similar considerations provide other criteria on which to base a pre-ionizing means design for existing arresters such as those that form the subject matter of the above-mentioned copending application.
  • the principal object of the present invention is to provide a novel, dependable, and inexpensive pre-ionizing and voltage grading means for arrester gaps that is simple and easy to manufacture;
  • Another object of the invention is to provide a minia: ture pre-ionizing means and fits conveniently in the limited space available in spark gap arrester plates.
  • Still another object of the invention is to provide a novel pre-ioniZer-grading device that produces a consistent sparkover at the proper voltage level in a valve type arrester gap.
  • Yet another object of the invention is to provide a highly efiicient arrester unit by elfecting a voltage-stress balance in a lightning arrester gap stack that is unbalanced only at the moment of pre-ionizer gap sparkover.
  • a further object of the invention is to provide a novel frequency responsive voltage grading means for an arrester gap assembly.
  • the present invention uses a single printed circuit package or module for each spark gap employing one grading resistor and one ionizing gap resistor in electrical contact with the major gap electrodes in a gap plate assembly.
  • the basic circuit module consists of a substrate such as alumina with two silvered contacts and electrodes in contact with the resistors, all afiixed to the substrate by printing or other suitable techniques.
  • the module is mechanically secured in a depression provided in an insulating gap plate so that one silvered contact is electrically contacted by a spark gap top electrode on one plate.
  • the second silvered contact is contacted by a bottom electrode fixed to the next gap plate of a stacked assembly.
  • the stack is balanced except for pre-ionizer sparkover, and at that moment can be unbalanced for any chosen degree of reduced voltage sparkover.
  • resistors are shown as the grading impedances, other types of suitable impedances may be used in place thereof or in combination therewith.
  • FIGURE 1 is an elevation view of a spark gap assembly capable of utilizing the novel means of the present invention
  • FIG. 2 is a schematic circuit diagram of the spark gap assembly of FIG. 1 wired in accordance with the principles of the present invention
  • FIG. 3 is a top plan view of an insulating plate with electrodes and a pre-ionizer-grading resistor module constructed in accordance with the principles of the invention
  • FIG. 4 is a partial view of the plate of FIG. 3 taken along lines IV--IV which includes a side elevation view of the resistor module;
  • FIG. 5 is an enlarged top plan view of the pre-ionizer grading resistor module shown in FIG. 3 and constructed in accordance with the principles of this invention
  • FIG. 6 is an enlarged side elevation view of module shown in FIG. 5.
  • spark. gap assembly 10 can have, for example, a specific voltage rating and can be combined with other identical units and disposed in an arrester housing in accordance with the usual or other techniques to form a complete arrester device having a desired overall voltage rating.
  • Gap assembly 10 comprises top and bottom end terminal plates 12 and 14 between which there is disposed and retained a stack of gap plates 20 and magnetic drive coil units 16 and 18.
  • a by-pass capacitor 55 may be disposed between end plate 14 and electrical contact support means 13 suitably connected to a spark gap terminal within one of the intermediate gap plates.
  • Capacitor 55 shorts out a portion of the gap stack with the reception of a fast rise time voltage (say 20 microseconds or less) for the purpose of maintaining an overall low voltage sparkover level.
  • capacitor 55 and parallel resistors 46 form an RC time constant circuit that makes the gap assembly frequency responsive.
  • FIG. 2 a schematic circuit diagram of the assembly in series circuit relationship with valve or arrester blocks 61 between power line 60, for which overvoltage protection is to be provided, and ground 62.
  • assembly 10 includes a plurality of series connected main spark gaps 28 in parallel with resistors 48-49 and 46 having novel and unique operating characteristics to be discussed more fully hereinafter.
  • a magnetic drive coil (16 and 18) At each end of the stack is a magnetic drive coil (16 and 18), respectively, protected by bypass gaps 16a and 18a all of which form a part of the subject matter of the above-mentioned copending application.
  • FIG. 3 applicants novel and unique pre-ionizer and voltage grading module is shown in place in insulating gap plate 20 that forms a part of the stack depicted in FIGS. 1 and 2.
  • the detailed top plan view of plate 20 shows the plate provided with a peripheral groove 22 and peripheral ridge 21 designed to receive a ridge (not shown) provided on the bottom side of. an adjacent plate to form interfitting means which hold gap plates 20 together.
  • the top and bottom sides of adjacent plates 20 form respective arc chamber regions within which gap electrodes 30 and 31 and runner electrode 32 are disand spring leaf type of contact 4 posed.
  • spark gap electrode 30 and runner electrode 32 are shown mounted on the top side of plate 20 whereas spark gap electrode 31 (shown in dot dash outline) is aflixed to the bottom side of an adjacent plate. When placed together, confronting edge surfaces of elec' trodes 30 and 31 form spark gap 28.
  • plate 20 is formed from alumina or glass bonded mica but it can be formed from other suitable materials that are electrically insulating, heat resistant and refractory or nonrefractory.
  • the novel resistor module 40 of this invention is secured in a tailored depression, between lateral depressions 26, in the top side of gap plate 20 and over which are disposed the ends of the spark gap electrodes 30 and 31 as best shown in FIG. 3.
  • an electrical spring leaf type of contact means 34 shown in dashed outline in FIG. 3.
  • One end of contact means 34 may be riveted or otherwise secured to and in electrical contact with spark gap electrode 30.
  • the other end is in electrical contact with contact surface 42 provided on the resistor module to be explained more fully hereinafter.
  • a means 35 (shown in dot-dash outline in FIG. 3) fixed on spark gap electrode 31 and electrically contacting surface 43 provided on resistor module 40.
  • FIGS. 5 and 6 show, in enlarged views, the unique, miniature resistor module 40 of the present invention.
  • the base of module 40 may consist of a substrate formed from any suitable material such as ceramic, glass-bonded mica or other similar materials.
  • On the top face thereof is disposed silvered contact surfaces 42 and 43 and electrodes 4'4 and 45 respectively.
  • Extending between contact surfaces 42 and 43 is a voltage grading resistor 46 and resistor sections 48 and 49.
  • These components may be affixed to the substrate by printing or other suitable techniques.
  • Extensions 44' and 45 of electrodes 44 and 45 can form test pads and contact points that give increased electrode surface contact area in the spark gap region for purposes of electrically checking the circuit module.
  • Contact surfaces 42 and 43 which may be made of silver or other suitable low electrical resistance metal, form the means for placing voltage grading and preionizing resistors across spark gap 28 formed by electrodes 30 and 31.
  • spark gap electrodes 30 and 31 may have spring contact means 34 and 35, respectively, that press against and rest on silvered surfaces 42 and 43, respectively.
  • other means may be provided to form a conductive path between the spark gap electrodes and the silvered contacts 42 and 43, spring contact means 34 and 35 shown for purposes of illustration only.
  • Grading resistor 46 is in electrical contact with silvered contacts 42 and 43 at its respective ends.
  • each spark gap 28- has a grading resistor of equal value across it at all times as best shown in the circuit diagram of FIG. 2. This arrangement evenly distributes the line potential across the series of gaps 28, thus distributing the voltage stress evenly over the stacked components of gap assembly 10.
  • the pre-ionizing gap arrangement with resistors 48 and 49 is disposed on the module substrate in electrical contact with silvered contacts 42 and 43 respectively and with pre-ionizing gap electrodes 44 and 45, respectively, disposed at the lower center portion of module plate 40 and aflixed thereto by printing or other suitable techniques.
  • Pre-ionizing gap electrodes 44 and 45 may be formed of a suitable electrical conducting material such as carbon or silver. Electrodes 44 and 45 form a preionizing gap 47 in conjunction with slot or aperture 50 provided in the substrate of module 40 as shown in FIGS. 5 and 6.
  • resistor combinations 48-49 are chosen with different 1 values so that the moment of sparkover and ionization the stack assembly can be unbalanced to any chosen degree of reduced spark-over voltage level.
  • a second, unbalanced resistance network is placed across main sp'ark gaps 28' through the agency of preionizing gap 47, resistors 48 and 4?, and aperture 50 in the substrate base.
  • Pro-ionizer gap 47 can be set to sparkover, say between 1.1 and 1.5 times the rated voltage.
  • Gaps 2'8 provide a low impedance path to ground in parallel with the two resistance networks composed of resistors 46 and 48, 49 respectively thereby effectively removing them from the circuit for the duration of the sparkover in gaps 28.
  • the surge current is discharged to ground and ionization ceases, balanced resistors 46 are effectively returned to the circuit.
  • Module plate 40 is secured in a fitted depression in gap plate 20.
  • the exposed surface of module plate 40 may lie in a plane slightly above the .plane of the surface supporting gap electrode 30 as shown in FIG. 4, or the exposed surface may be flush wit-h the gap electrode supporting surface.
  • the depressions 26 in the gap plate 20 extend along the left and right edges of module plate 40 for purposes of accommodating spring leaf contact means 34 and 35. In this manner good contact is insured between silvered contact surfaces 42 and 43 and the spring leaf contact means.
  • a small, voltage grading-pre-ionizing means is provided that neatly fits in the limited area available be tween spark gap electordes contained in gap plates such as shown and described in the copending application mentioned above.
  • Such plates can be easily modified to accommodate applicants novel pre-ionizer-grading module 40. Consequently, the costs of producing such an improved gap and the manufacturing ease of placing and securing the module in the gap greatly enhance the .novelty and uniqueness of the present invention which simultaneously provides a highly efiicient gap assembly because all parts therein are equally stressed, yet unbalanced at the moment of sparkover which provides a lower and consistent sparkover voltage level for the assembly.
  • capacitor 55 can be provided, in parallel with some of the resistors 46, to take over the function of lowering the voltage when very fast time surges make the grading and preionizing resistances less effective.
  • capacitor 55 can be provided, in parallel with some of the resistors 46, to take over the function of lowering the voltage when very fast time surges make the grading and preionizing resistances less effective.
  • capacity 55 and grading resistors 46 form an RC time constant circuit.
  • resistor slugs, contacts and electrodes may be attached to module 40 in place of the printed components described.
  • other suitable types of grading impedances such as capacitors, may be :used in place of resistors 46, 48 and 49.
  • the invention is not limited to the specific arrangement shown and described, but is intended to include all modifications which fall within the spirit and scope of the invention.
  • a spark gap device comprising:
  • preionizing the main gap means for preionizing the main gap, said preionizing means including the inner ends of the separated impedance means.
  • a spark gap device comprising:
  • said inner end portions comprising a preionizing gap for said main spark gap.
  • An arrester gap comprising a stack of insulating plates, each of said plates having a main gap electrode secured on opposite sides thereof, means conductively connecting the gap electrodes associated with each of said plates, each adjacent pair of said plates formed to provide an arc-chamber, the gap electrodes of the confronting plate sides having respective arcing surfaces and confronting portions disposed to provide a sparkover region, a resistor electrically connected to provide a voltage grading path across the gap electrodes, a second resistor disposed adjacent the sparkover region and electrically connected to the main gap electrodes, said second resistor being separated into two parts, and a preionizing gap, said preionizing gap including the inner ends of said separated resistor.
  • a spark gap device having at least one pair of spaced apart electrodes forming a main spark gap, a voltage grading and preionizing means disposed between said electrodes, said means comprising a first resistor disposed on a support member and in electric-a1 contact with the spaced apart electrodes, a second resistor disposed on said support member and divided into two parts, each part having one end in electrical contact with an adjacent electrode of said electrode pair, the other ends of said second resistor being spaced apart and adjacent a slotted recess in the support member between the resistor ends, said ends of the resistor adjacent the slotted recess comprising a small spark gap for preionizing the main gap.
  • a spark gap device having at least one pair of spaced apart electrodes, a voltage grading and preionizing means disposed between the electrodes, said means comprising a balanced voltage grading resistor and an unbalanced voltage grading resistor, electrode means disposed on a support member and in electrical contact with adjacent electrodes of the electrode pair, said preionizing resistor being divided into two substantially equal parts with adjacent ends each having one electrode means disposed on the support member and on each side of an aperture in the support member extending in a direction parallel to the axis of the electrode means and perpendicular to the axis of the resistor parts.
  • An arrester gap arrangement comprising at least one pair of spaced apart electrodes forming a main spark gap therebetween, the electrodes being generally flat and elongated with the longitudinal axis thereof extending in generally parallel relation, the electrodes having narrow longitudinal extensions on one end thereof with confronting surfaces diverging away from each other to form an enlarged area therebetween, a circuit module disposed in said area and between said confronting surfaces, said module containing a voltage grading resistor electrically connected across said electrode extensions, a second resistor in parallel with the grading resistor and in electrical contact with said electrode extensions, said second resistor separated into two substantially equal sections, and a small spark gap for preionizing the main gap, said small gap formed between the two sections of the separated resistor.
  • An arrester gap arrangement comprising a stack of insulating plates, each of said plates having a gap electrode secured on opposite sides thereof, means conductively connecting the gap electrodes associated with each of said plates, each adjacent pair of said plates formed to provide an arc chamber, the gap electrodes of the confronting plate sides having respective arcing surfaces and 25 confronting portions disposed to provide a sparkover region in a plane substantially parallel to the plate sides, each of said plates having a circuit module secured to one side thereof and disposed between longitudinal extensions of the gap electrodes, said module containing a voltage grading resistor oonnected across said gap electrode extensions and a second resistor connected in parallel with the grading resistor and divided substantially in half, a preionizing circuit adjacent said sparkover region, said preioniz ing circuit formed by the divided resistor, the grading resistors being of equal value to provide equal voltage stress across arrester gap components, the second resistors being of unequal value to provide a lower overall arrester sparkover voltage.

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US492087A 1965-10-01 1965-10-01 Lightning arrester gap and grading means Expired - Lifetime US3377503A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US492087A US3377503A (en) 1965-10-01 1965-10-01 Lightning arrester gap and grading means
DE19661563924 DE1563924A1 (de) 1965-10-01 1966-08-12 UEberspannungsableiter mit Steuerwiderstaenden und Vorionisierungs-Funkenstrecken
AT802866A AT266967B (de) 1965-10-01 1966-08-24 Überspannungsableiter mit Steuerwiderständen und Vorionisierungs-Funkenstrecken
CH1392366A CH446501A (de) 1965-10-01 1966-09-27 Uberspannungsableiter mit Steuerwiderständen und Vorionisierungs-Funkenstrecken
JP41064726A JPS5218384B1 (OSRAM) 1965-10-01 1966-10-01

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US492087A US3377503A (en) 1965-10-01 1965-10-01 Lightning arrester gap and grading means

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US3377503A true US3377503A (en) 1968-04-09

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US492087A Expired - Lifetime US3377503A (en) 1965-10-01 1965-10-01 Lightning arrester gap and grading means

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US (1) US3377503A (OSRAM)
JP (1) JPS5218384B1 (OSRAM)
AT (1) AT266967B (OSRAM)
CH (1) CH446501A (OSRAM)
DE (1) DE1563924A1 (OSRAM)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3489949A (en) * 1967-11-13 1970-01-13 Gen Electric Lightning arrester with main and preionizing gaps
US3496409A (en) * 1966-10-11 1970-02-17 Ohio Brass Co Spark gap and discharge control apparatus
US3497764A (en) * 1967-09-25 1970-02-24 Gen Electric Overvoltage protective apparatus having a pilot gap circuit arrangement for controlling its actuation
US3515934A (en) * 1968-01-17 1970-06-02 Mc Graw Edison Co Lightning arrester sparkover control
US20130131526A1 (en) * 2009-11-16 2013-05-23 Koninklijke Philips Electronics N.V. Overvoltage protection for defibrillator

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1059657A (fr) * 1951-07-11 1954-03-26 D App Electr Sprecher & Schuh éclateur de parafoudre pré-ionisé
US2890389A (en) * 1955-03-24 1959-06-09 Gen Electric Lightning arrester improvements
US3259780A (en) * 1964-07-06 1966-07-05 Gen Electric Electric gap device using porous material in the arc chamber

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1059657A (fr) * 1951-07-11 1954-03-26 D App Electr Sprecher & Schuh éclateur de parafoudre pré-ionisé
US2890389A (en) * 1955-03-24 1959-06-09 Gen Electric Lightning arrester improvements
US3259780A (en) * 1964-07-06 1966-07-05 Gen Electric Electric gap device using porous material in the arc chamber

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3496409A (en) * 1966-10-11 1970-02-17 Ohio Brass Co Spark gap and discharge control apparatus
US3497764A (en) * 1967-09-25 1970-02-24 Gen Electric Overvoltage protective apparatus having a pilot gap circuit arrangement for controlling its actuation
US3489949A (en) * 1967-11-13 1970-01-13 Gen Electric Lightning arrester with main and preionizing gaps
US3515934A (en) * 1968-01-17 1970-06-02 Mc Graw Edison Co Lightning arrester sparkover control
US20130131526A1 (en) * 2009-11-16 2013-05-23 Koninklijke Philips Electronics N.V. Overvoltage protection for defibrillator
US9901275B2 (en) * 2009-11-16 2018-02-27 Koninklijke Philips N.V. Overvoltage protection for defibrillator

Also Published As

Publication number Publication date
JPS5218384B1 (OSRAM) 1977-05-21
AT266967B (de) 1968-12-10
DE1563924A1 (de) 1970-05-14
CH446501A (de) 1967-11-15

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