Abstract:
A lightening conductor ( 10 ) for lightning protection of structures ( 37 ), particularly of mobile structures ( 37 ), comprises a conduit ( 18 ) connected to a mast ( 12 ) and provided for dissipation of a lightning current. The mast ( 12 ) is telescopable so that the height of the lightening conductor ( 10 ) can be individually adapted to local conditions and is transported conveniently.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a lightening conductor provided to dissipate the lightening current of a lightening stroke so as to protect structures such as e.g. buildings, tents and the like from damage caused by lightening strokes.  
         [0002]     Known lightening conductors normally comprise a long conductive rod projecting above the structure to be protected so that lightening generated during a thunderstorm will not strike the structure but the rod. For this purpose, the rod is normally fastened to the structure at a point as high up on the structure as possible. Connected to the rod is a conduit which, at a site remote from the structure, is grounded for dissipation of the current generated by a lightening stroke.  
         [0003]     From DE 20 2004 003 233 U1, it is known to attach a lightening conductor of the above type to the antenna mast of a cellular network antenna which is to be protected from lightning.  
         [0004]     Disadvantageously, a lightening conductor of the above outlined type requires a constructional component having significant stability and being arranged at a considerably elevated position so that the lightening conductor can function properly for protecting the structure from lightening strokes. Thus, the selection of a suitable site for the lightening conductor is subjected to considerable restrictions. Particularly if lightning protection is desired for mobile structures such as e.g. tents, it may be possible only with difficulties to make a part of the tent available for use as a sufficiently stable and accessible attachment site.  
         [0005]     It is an object of the present invention to provide a lightening conductor which is improved for use in a larger variety of places and which is particularly suited for lightning protection of mobile structures.  
         [0006]     According to the present invention, the above object is achieved by the features of claim  1 .  
       SUMMARY OF THE INVENTION  
       [0007]     The lightening conductor of the present invention, provided for lightning protection of structures and particularly of mobile structures, comprises a mast and at least one electrical conduit connected to the mast for dissipation of a lightning current. In this arrangement, the lightning to be dissipated can be captured by the conduit and/or by a lightning rod attached to the mast while insulated therefrom; in the latter case, the lightning rod is electrically connected to the conduit. According to the invention, the mast is at least partially telescopable so that at least a partial section of the mast is variable in length, preferably in a continuous manner.  
         [0008]     Since the mast is telescopable, a conical protection space provided by the lightening conductor in which persons and objects will be protected from lightning strokes can be individually adapted to the local conditions; thus, particularly, a lightning protection space covered by the above protection cone and having the to-be-protected structures arranged therein can be adapted as required in the respective situation. Particularly, the mast of the lightening conductor in its retracted state can be of a length which is short enough to allow for easy transportation of the lightening conductor so that the lightening conductor can be reused a plurality of times at different sites. Since the lightening conductor can be transported easily, it will be especially suited for lightning protection of mobile structures such as e.g. tents, conveyance goods which have been placed outdoors, or apparatus which are not in easy reach under the logistic aspect.  
         [0009]     According to a preferred embodiment, the mast is arranged to be telescoped pneumatically. This, for instance, allows for the connection of a pressurized air line and/or a pressurized air cartridge via a pressurized air connector so that the mast can be extended quickly and easily. Further, the pneumatic pressure required for telescoping the mast can be provided by an air pump connected to the mast and operable particularly by hand or with the aid of a foot. Preferably, the mast is provided with a valve by which the air needed for telescoping the mast can be discharged. The valve can also be used for the supply of pressurized air, if required. Preferably, the valve can be operated manually.  
         [0010]     Preferably, the telescopable mast of the lightening conductor comprises a plurality of mast elements interconnected for telescoping movement relative to each other. In this arrangement, respectively adjacent mast elements, i.e. mast elements which in the extended state directly follow each other, can be connected to each other by a fastening element and can be arrested and/or locked relative to each other. Particularly, the fastening element comprises a spring-biased fastening element in order to automatically connect the mast elements, thus effecting a permanent locking of the mast elements to each other, which locking effect can be released only by user intervention. This makes it possible, for instance, by application of a pneumatic pressure, to provide a force which by a simple manipulation can be utilized for moving the respectively released mast element from a retracted state into an extended state.  
         [0011]     Preferably, the mast can be temporarily fastened to an underlying ground surface. For this purpose, the mast is provided e.g. with a foot adapted for attachment to the ground surface. The foot can be configured e.g. as a tripod to be attached to the ground surface with the aid of anchor stakes of the type normally used e.g. for putting up tents. To compensate for unevennesses of the ground surface, the mast is provided with leveling elements, particularly of the height-variable and length-variable type, by which the mast can be leveled to give it a substantially vertical orientation.  
         [0012]     Preferably, the mast has mast spacers connected thereto so that the conduit can be guided at a distance from the mast and substantially parallel thereto. At least some of the spacers can be formed with eyes which are used for guidance of the conduit therethrough; these mast spacers are preferably connected to the mast elements. Further, bottom spacers can be provided for guiding the conduit at a distance from the underlying ground surface. Thereby, the conduit can be guided substantially horizontally away from the mast. Preferably, on its end facing away from the mast, the conduit is connected with a deep grounding means for dissipating the lightning current into the underlying ground. It can also be provided, particularly in case of hard, compact underlying ground, to connect the conduit to a star-type grounding means which, while arranged at a low depth, is oriented substantially horizontally in the ground.  
         [0013]     Preferably, a plurality of lightening conductors of the invention are combined into a lightning protection system wherein the lightening conductors are arranged in such a manner that the individual protection spaces of the respective lightening conductors will form a common cohesive lightning protection space. Particularly, this lightning protection space is large enough to accommodate tents to be put up therein for protection from lightning. The lightning protection space has a surface area of at least 11mx11m, preferably at least 20mx20m and most preferably at least 25mx25m. The electrical conduits of the individual lightening conductors are preferably guided to lead away from the common lightning protection space wherein the tents are arranged.  
         [0014]     A preferred embodiment of the invention will be described in greater detail hereunder with reference to the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a schematic lateral view of the lightening conductor of the invention;  
         [0016]      FIG. 2  is a schematic sectional view of a telescopable mast of the lightening conductor illustrated in  FIG. 1 ; and  
         [0017]      FIG. 3  is a schematic plan view of a lightning protection system of the invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]     The lightening conductor  10  illustrated in  FIG. 1  comprises a mast  12  to which is connected, via an insulating element  14  having a length of about 1.5m, a lightning rod  16  for capturing lightning, which rod is made of aluminum and has a length of about 2m. The lightning rod  16 , being insulated from the mast  12  which has a length of about 6m, has connected thereto an electrical conduit  18  which is vertically guided in parallel to mast  12  with the aid of mast spacers  20 . For this purpose, the electrical conduit  18  is guided through eyes  22  formed in the mast spacers  20 . In the lower region of mast  12 , conduit  18  is deflected by about 900, thus extending substantially horizontally. In its horizontal part, conduit  18  is held at a distance to the underlying ground  26  by means of bottom spacers  24 . At a distance of about 10m from mast  12 , conduit  18  is connected to one or a plurality of deep grounding means  28  extending about three meters into the ground  26 .  
         [0019]     The mast spacers  20  attached to mast  12  can also be provided as cable ties which, by the effect of their own stiffness, keep the conduit  18  guided on mast  12  at a distance of about one meter from the mast.  
         [0020]     Mast  12  is further fastened to a tripod  30  which, by use of anchor stakes  32 , is tightly fastened to the underlying ground  26  on a temporary basis.  
         [0021]     In case of a thunderstorm, lightning will tend to strike primarily into the lightning rod  16  of lightening conductor  10  so that the lightning current can be dissipated into the ground  26  via conduit  18 . As a result, the lightening conductor  10  generates a protection cone  36  starting from an upper tip  34  of the lightening conductor. Within this cone, objects such as e.g. a tent  37  can be arranged for protection from lightening.  
         [0022]     Mast  12  is arranged to be telescopically extended and retracted ( FIG. 2 ) and comprises a first mast element  38  guided for movement in a second mast element  40 . For guidance of the first mast element  38  in the second mast element  40 , the first mast element  38  in an upper region thereof is passed through a guide ring  42  wherein the contact of a the guide ring  42  with the first mast element  38  is accomplished by a slide ring  44  preferably made of Teflon. The guide ring  42  is tightly connected to the second mast element  40 , e.g. by clamping, and may be provided with a fastening element (not shown) for locking the first mast element  38  to the second mast element  40 . In the lower region, the first mast element  38  is guided in the second mast element  40  via a piston  46 , the contact of the piston  46  to the second mast element  40  being effected via further slide rings  44 .  
         [0023]     For pneumatic actuation of the telescopable mast  12 , air pressure is caused to press against piston  46  and/or a closure member of mast  12  in the upper region whereby the first mast element  38  is pressed or pulled out from the second mast element  40  in the direction schematically indicated by arrow  48 . To avoid escape of the pressurized air, piston  46  is provided, at the site of its contact to the first mast element  38  and at the site of its contact to the second mast element  40 , with a respective O-ring  50  and/or a sealing means of a comparable effect.  
         [0024]     In a further embodiment of a lightning protection system  52  illustrated in  FIG. 3 , four preferably identical lightening conductors  10  are provided, with their protection cones  36  forming a common lightning protection space  54  which is suited for arrangement of e.g. a plurality of tents  37  therein. The lightening conductors  10  each are provided with two electrical conduits  18  leading away from the tents  37  and the lightning protection space  54  at an angle α= about 90° C. relative to each other. This means that the conduits  18  arranged in the lightning protection space  54  are oriented to point away in outward directions from the lightning protection space  54 . Depending on the lengths of the conduits  18  the deep grounding means  28  can be arranged inside or outside the lightning protection space  54 .