Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G13/00—Installations of lightning conductors; Fastening thereof to supporting structure
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G13/00—Installations of lightning conductors; Fastening thereof to supporting structure
  • H02G13/80—Discharge by conduction or dissipation, e.g. rods, arresters, spark gaps

Definitions

• This invention relates to improvements in lightning protection, and in particular relates to improvements in the lightning capture efficiency of lightning conductors, or more specifically the air terminal portion of a lightning conductor system.
• ESE Early Streamer Emission
• One ESE terminal uses a pulse format to eliminate the observed pauses in up streamer development.
• the other as disclosed in United States Patent 4,760,213 (J.R. Gumley) uses a spherical geometric shape in the presence of electrostatic fields in order to minimize corona. The same device creates triggering impulses across a spark gap on the approach of the precursor down leader. This triggering impulse creates free electrons and photo ionization to aid the development of an upward leader.
• An alternative technology seeks to prevent lightning strikes at a particular location by neutralizing the charge differential between a cloud and the location before a 'flashover point' occurs. Such a 'Dissipation system' is disclosed in United States Patent 5,043,527 (R.B. Ca ⁇ enter).
• DSE Delayed Streamer Emission
• one broad form of the invention provides a lightning protection system for a structure or location, including an Early Streamer Emission (ESE) air terminal located on said structure or at said location, characterized in that, at least one Delayed Streamer Emission (DSE) element is located on said structure, or at said location, strategically spaced from said ESE terminal whereby the protective radius of said ESE terminal is extended.
• ESE Early Streamer Emission
• DSE Delayed Streamer Emission
• a further broad form of the invention provides a method of lightning protection characterized in that, one or more Early Streamer Emission (ESE) air terminals are arranged in strategic combination with a plurality of Delayed Streamer Emission (DSE) elements to protect a structure or location be directing lightning strikes to said ESE terminal or terminals.
• ESE Early Streamer Emission
• DSE Delayed Streamer Emission
• a still further broad form of the invention provides a lightning protection system for a structure or location characterized in that, a plurality of passive lightning termination devices with respective positive and negative up-leader time advantage are strategically combined at said structure or location to extend the attractive radius of a primary collector.
• a still further form of the invention provides a Delayed Streamer Emission (DSE) element characterized in that, it includes a plurality of upwardly diverging finials providing corona-forming points and a series impedance to inhibit imitation and subsequent propagation of lightning up-leaders.
• DSE Delayed Streamer Emission
• Fig. 1 is a diagrammatic view of an arrangement for determining the attractive radius of a conventional Franklin rod on a structure
• Fig. 2 is a diagrammatic view, similar to that of Fig. 1, with an ESE terminal in place of a Franklin rod;
• Fig. 3 is a diagrammatic view, similar to that of Figs. 1 and 2, with ESE and DSE terminals in place in accordance with the invention;
• Fig. 4 is a side elevation of a DSE array according to an embodiment of the present invention.
• Fig. 5 is a perspective view of a DSE element suitable for installation on the parapet of a structure
• Fig. 6 is a perspective view of an alternative to the element of Fig. 5.
• Fig. 1 there is shown an arrangement determining the attractive radius of a conventional Franklin Rod 10 on a structure 12.
• This downleader charge is also related to the peak discharge current of the subsequent stroke.
• the latter has been measured by many researchers and it is now possible to statistically protect against ail discharges above a given peak current. For example, 93% of all first stroke discharges exceed lOkA which relates to a leader charge of about 3 Coulombs.
• Fig. 2 there is shown the effect of an ESE 14.
• ⁇ l is the distance advantage due to the ESE effect.
• a time delay occurs from the time that a critical electrical field strength is achieved to the time of actual launch and propagation of an up-leader. Reducing this time delay can be represented as an increase in initiation distance.
• ⁇ l is derived from the time advantage of the ESE terminal 14 multiplied by the up-leader propagation velocity to obtain a distance advantage. There is no ⁇ l for natural points on a structure which still retain an initiation distance D.
• Fig. 3 there is shown an arrangement according to the present invention in which the outer structural points 16 may not have an initiation distance D.
• the points 16 are designed to create corona and actually act to delay the initiation of an up leader.
• the outer structural points 16 are provided with DSE devices which are strategically placed and serve to extend the protected area as will become apparent.
• the initiation distance of the points 16 will be D- ⁇ l.
• Fig. 3 shows that such a delay actually enhances the capture ability of the ESE terminal by further increasing the value of Rp.
• Rp3 (Fig. 3) is greater than both Rp2 (Fig. 2) and Rpl (Fig. 1).
• a suitable ESE terminal is well described in aforementioned United States Patent 4,760,213 and the disclosure thereof is incorporated herein by cross-reference.
• the reduction of predischarge corona and the presence of a triggering arc contributes to an early launch ability.
• Such an ability may also be available in other EDE devices.
• DSE concept is opposed to that disclosed in United States Patent 4,760,213.
• the aim now is to seek, by design, those structural points which may compete with the ESE terminal and equip such points with devices to retard up-leader generation.
• Such devices are multipointed metallic systems designed to create a space charge immediately above them.
• the devices utilized in this invention are not designed to capture a discharge but simply to retard leader development so that capture priority lies with the ESE terminal.
• Other types of DSE devices may be used in the system of the invention.
• Fig. 4 shows a multiplicity of elements 18 according to the invention which act to delay up-leader initiation and meet the DSE criteria for the system of this invention.
• Fig. 4 one exemplary multi-point arrangement is shown, which is suitable for long parapets on structures.
• Each element 18 consists of three or more finials 20, preferably formed from stainless steel, each having a sha ⁇ tip.
• Preferred tip separation is about 250mm, with about 250mm separating the tips of adjacent elements 18.
• An insulating portion 22 comprising a high glaze ceramic insulator, supports finials 20.
• An internal resistor 24 is located within insulator 22 to limit up leader propagation current.
• An earth plate 26 supports elements 18.
• the plate 26 is formed from stainless steel, and in adapted to be secured by bolts 28 or other fixing means to a parapet of a structure 12.
• the overall length of the assembly of Fig. 4 is preferably about 2m, with a height above plate 26 of about 500mm.
• Figs. 5 and 6 show two examples of DSE strips generally according to Fig. 4.
• Fig. 5 shows one strip 30 on a parapet 32.
• Fig. 6 shows another design 34 showing a resistor 24 therein.
• Figs. 4 to 6 act in the following way.
• the multiplicity of points combine to emit corona current.
• the impedance is a series resistor it will not inhibit this action, even though its value may be in the order of 1 megohm.
• Each point may emit 5 microamps in an electric field of 5kV/m and, if thirty points were attached the total drain would be about 150 microamps.
• the voltage drop would be a mere 150 volts compared with the 100 megavolts appearing between cloud and ground.
• the resistor has negligible effect on corona generation, and the resulting space charge would mask the E field observed due to an approaching down leader. This downleader would then have to approach much closer to cause up leader initiation.

Landscapes

• Elimination Of Static Electricity (AREA)
• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)
• Inorganic Insulating Materials (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

Country Status (8)

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• 1994
  • 1994-01-31 WO PCT/AU1994/000040 patent/WO1994017578A1/en not_active Application Discontinuation
  • 1994-01-31 EP EP94905624A patent/EP0681753A1/en not_active Withdrawn
  • 1994-01-31 CA CA002154798A patent/CA2154798A1/en not_active Abandoned
  • 1994-01-31 JP JP6516494A patent/JPH08505981A/ja active Pending
  • 1994-01-31 KR KR1019950703134A patent/KR960700551A/ko not_active Withdrawn
  • 1994-01-31 CN CN94191036A patent/CN1116885A/zh active Pending
  • 1994-01-31 BR BR9406315A patent/BR9406315A/pt not_active Application Discontinuation
  • 1994-01-31 AU AU59665/94A patent/AU670360B2/en not_active Ceased

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