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US 6,320,119 B1Granted
Lightning air terminals and method of design and application
AssigneeERICO International Corporation
InventorJohn Richard Gumley
Life of this patent
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AssigneeERICO International Corporation
InventorJohn Richard Gumley
Estimating the term…
Air terminals of two types having curved surface electrodes that act passively or dynamically to minimize or further reduce corona during the close approach of the down leader. In the first type, a fully grounded passive terminal, suitably located and comprising a conductive curved surface of a given radius on a grounded rod of given height, is located and suitably dimensioned in order to minimize corona discharges until the median field rises to a level sufficient to support streamer to leader conversion, as described below. In the second type, dynamic action is achieved by allowing the curved surface to float upwardly in voltage by use of capacitive coupling to the approaching leader. The raising of voltage being in the same polarity as the leader, acts to reduce the electric field immediately above, with consequent reduction in corona. When a flashover point is reached between the curved surface and the main earthed electrode there are provided free electrons in avalanche mode, and the curved surface is simultaneously grounded through the arc. This grounding causes an instant increase in the electric field immediately above the terminal. Streamer formation is enhanced by the liberation of free electrons, the photoionization created by the arc, and the instant increase in the electric field strength ahead of the streamer.
An air terminal including a curved conductive surface capacitively spaced from a permanent grounded upper central rod, said curved conductive surface having shape and size to optimize the formation of surface corona and streamer only when the median field strength is sufficient to support streamer to propagation of a leader, the curved surface being insulated from said central grounded rod, with an annular air gap there between which acts as a spark gap, an electronic circuit joining the curved conductive surface to ground and, in conjunction with the calculation of the capacitive leader coupling according to the dimension of the conductive surface, and having a value such that in a rising electric field of between 108 Vm−1s−1 and 3×109 Vm−1s−1 the terminal will allow triggering of an arc at the annular air gap, but at lower rates of rise of electric field prevent such a triggering arc.
An air terminal including a curved conductive surface capacitively spaced from a permanent grounded upper central rod, said curved conductive surface having shape and size to optimize the formation of surface corona and streamer only when the median field strength is sufficient to support streamer to propagation of a leader, the curved surface being insulated from said central grounded rod, with an annular air gap there between which acts as a spark gap, an annular ring located within the spark gap but insulated from both the ground rod and the curved surface, and a resistance or impedance means connected between the curved surface and the annular ring, operative to extend the time duration of the triggering arc.
A lightning air terminal comprising a central earth rod, a curved conductive surface surrounding said rod and insulated from the rod, an air gap between the surface and the rod acting as a spark gap, a non-conducting ring projecting into the spark gap, and projecting proud of the shortest spark track to deflect the spark upwardly to enter a more intense electric field during storm conditions.
A lightning air terminal comprising a central earth rod, a curved conductive surface surrounding said rod and insulated from the rod, an air gap between the surface and the rod acting as a spark gap, a non-conducting ring projecting into the spark gap, and projecting proud of the shortest spark track to deflect the spark upwardly to enter a more intense electric field during storm conditions, and an arc time extension ring means between said non-conducting ring and said curved surface.
A lightning air terminal comprising a central earth rod, a curved conductive surface surrounding said rod and insulated from the rod, an air gap between the surface and the rod acting as a spark gap, a non-conducting ring projecting into the spark gap, and projecting proud of the shortest spark track to deflect the spark upwardly to enter a more intense electric field during storm conditions;
A lightning air terminal comprising a central earth rod, a curved conductive surface surrounding said rod and insulated from the rod, an air gap between the surface and the rod acting as a spark gap, a non-conducting ring projecting into the spark gap, and projecting proud of the shortest spark track to deflect the spark upwardly to enter a more intense electric field during storm conditions, wherein the top of said central earth rod is blunt and contoured to minimize electric field intensification.
A lightning air terminal comprising a central earth rod, a curved conductive surface surrounding said rod and insulated from the rod, an air gap between the surface and the rod acting as a spark gap, a non-conducting ring projecting into the spark gap, and projecting proud of the shortest spark track to deflect the spark upwardly to enter a more intense electric field during storm conditions, and wherein the top of the central earth rod forms an annular laterally projecting sharp lip.
A lightning air terminal comprising a central earth rod, a curved conductive surface surrounding said earth rod and insulated from the rod, an air gap between the surface and the rod acting as a spark gap, and an arc time extension conducting ring means positioned in said air gap between said surface and said earth rod operative to extend in time the formation of a spark.
Dependencies are inferred from the claim text.