CA1104637A - Lightning arrester for aerial electric power lines - Google Patents
Lightning arrester for aerial electric power linesInfo
- Publication number
- CA1104637A CA1104637A CA319,875A CA319875A CA1104637A CA 1104637 A CA1104637 A CA 1104637A CA 319875 A CA319875 A CA 319875A CA 1104637 A CA1104637 A CA 1104637A
- Authority
- CA
- Canada
- Prior art keywords
- core
- tower
- sheath
- improvement
- power line
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
- H01R4/58—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation characterised by the form or material of the contacting members
- H01R4/64—Connections between or with conductive parts having primarily a non-electric function, e.g. frame, casing, rail
-
- 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
-
- 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
- H02G7/00—Overhead installations of electric lines or cables
- H02G7/22—Arrangements of earthing wires suspended between mastheads
Abstract
LIGHTNING ARRESTER FOR AERIAL ELECTRIC POWER LINES
ABSTRACT OF THE DISCLOSURE
A tower extends above the ground and supports at a level above the ground at least one aerial electric power line.
A coaxial shielded conductor includes a central conductor core, an outer conducting sheath, and an insulating layer between the core and the sheath. The upper end of the core is electrically connected to a conducting member adjacent the top of the tower.
Both the lower end of the core and the lower end of the sheath are grounded. The sheath extends from substantially the area of connection of the core to the conducting member to a position below the power line, such that the lower end of the sheath is spaced below the power line at least by a distance sufficient to exclude the formation of a discharge arc between the core and the power line upon a lightning discharge.
ABSTRACT OF THE DISCLOSURE
A tower extends above the ground and supports at a level above the ground at least one aerial electric power line.
A coaxial shielded conductor includes a central conductor core, an outer conducting sheath, and an insulating layer between the core and the sheath. The upper end of the core is electrically connected to a conducting member adjacent the top of the tower.
Both the lower end of the core and the lower end of the sheath are grounded. The sheath extends from substantially the area of connection of the core to the conducting member to a position below the power line, such that the lower end of the sheath is spaced below the power line at least by a distance sufficient to exclude the formation of a discharge arc between the core and the power line upon a lightning discharge.
Description
BACKGROUND OF THE INVENTION 11~4~3'~
The present invention relates to a lightning arrester or a system for protecting against a lightning discharge an aerial electric power line supported above the ground by a tower.
It is well known that aerial electric power lines, supported above the ground by a tower, are subject to damage when struck by lightning. One known system for protecting such aerial electric power lines from lightning is to stretch a protection conductor wire along the towers supp~rting the aerial electric power lines, at a position above the aerial electric power lines, with such protection conducting wire being grounded by means of a ground wire or by one or more of the towers, if the towers are metal towers. The purpose of such protection conducting wire is to receive the lightning discharge and to conduct the discharge to the earth.
However, such known system for protecting the aerial electric power lines suffers from an inherent disadvantage.
Specifically, it is not possible to avoid the risk of a secondary arc discharge between the tower and one or more of the aerial electric power lines. That is, as the lightning discharge is passed downwardly along the tower from the protection conducting wire to ground, there often occurs a secondary arc ~etween the tower or ground wire and one or more ~f the electric power lines. Such secondary arc discharge damages the power networ~ of the electric power lines, and t~us the protection offered by the upper protection conducting wire is incomplete.
The present invention relates to a lightning arrester or a system for protecting against a lightning discharge an aerial electric power line supported above the ground by a tower.
It is well known that aerial electric power lines, supported above the ground by a tower, are subject to damage when struck by lightning. One known system for protecting such aerial electric power lines from lightning is to stretch a protection conductor wire along the towers supp~rting the aerial electric power lines, at a position above the aerial electric power lines, with such protection conducting wire being grounded by means of a ground wire or by one or more of the towers, if the towers are metal towers. The purpose of such protection conducting wire is to receive the lightning discharge and to conduct the discharge to the earth.
However, such known system for protecting the aerial electric power lines suffers from an inherent disadvantage.
Specifically, it is not possible to avoid the risk of a secondary arc discharge between the tower and one or more of the aerial electric power lines. That is, as the lightning discharge is passed downwardly along the tower from the protection conducting wire to ground, there often occurs a secondary arc ~etween the tower or ground wire and one or more ~f the electric power lines. Such secondary arc discharge damages the power networ~ of the electric power lines, and t~us the protection offered by the upper protection conducting wire is incomplete.
-2-- ~104637 Furthermore, it is known from applicant's previous U.S. Patent No. 3,919,956 to protect ships or buildings by means of a coaxial shielded cable which is connected to a lightning rod and which is grounded.
SUMMARY ` OF THE INVENTION ~ 4t;37 With the above discussion in mind, it is the principal object of the present invention to provide an improved lightning arrester system or system from protecting against a lightning 'discharge aerial electric power lines supported abo~e the ground by towers.
It is a further object of the present invention to provide such a system which for practical purposes avoids the risk, not only of lightning striking the electric power lines, but which also avoids the risk of a secondary arc discharge between the system and the electric power lines.
These objects are achieved in accordance with the present invention by the provision of a shielded conductor including a central conductor core, an outer conducting sheath, and an insulating layer between the core and the sheath. The upper end of the core is electrically connected to a conducting member adjacent the top of the tower which supports the electric power lines above the ground. Both the lower end of the core and the lower end of the sheath are grounded. The sheath extends from substantially the area of connection of the core to the conducting member to a position bel~w the power line, with the lower end of the sheath being spaced below the power line at least by a distance sufficient to exclude the formation of a secondary arc discharge between the core and the power line.
The coaxial shielded cable may ~e employed on all of the towers which support the aerial electric power lines.
However, such arrangement is not necessary, as long as those towers which are most susceptible and exposed to lightning are each provided with a coaxial shielded cable. Those skilled in the art would be readily able to determine which towers are most exposed to lightning merely by studying historical statistics of a given power line system or similar power line systems. Normally, lightning discharges occur most frequently on hills or where the tower is located in wet or marshy ground.
The coaxial shielded cable which is employed as a lightning arrester or as a system for protecting the electric power lines from lightning di~charge may be the coaxial shielded cable ~isclosed in the above mentioned U.S. Patent No. 3,919,956, or may be any other similar coaxial shielded cable which includes a central conductor core, an outer conducting sheath coaxially surrounding the central conductor core, and an insulating layer between the central core and the outer sheath.
The upper end of the core is electrically connected to a conducting member positioned adjacent the top of the tower. Such conducting member may be a conventional protectiGn conductor wire supported by and extending along the towers at a position above the aerial electric power lines. Alternatively, the conducting member may be one or more conventional lightning rods located at the top of the tower. Further, the conducting member may be a metal portion on the top of the tower. The upper end of the outer coaxial sheath is not electrically connected to the conducting member or to the central core.
111~4~37 Both the lower end of the core and the lower end of the sheath are grounded, The upper end of the sheath is located adjacent the area of connection of the core to the conducting member. The sheath must extend downwardly to a position below the lowermost electriC power line such ~hat the lower end of the sheath is spaced below the lowermost electric power line at least by a distance sufficient to exclude or prevent the formation of a secondary arc discharge between the core and any of the electric power lines. Thusl the outer conducting sheath, which is insulated from the central conductor core, acts as a shield to prevent a secondary arc discharge from the core which operates to ground a lightning discharge striking the conducting member and any of the electric power lines. The 1~ distance by which the lower end of the sheath must be spaced from the lowermost electric power line to prevent such secondary arc discharge would be readily determinable by one skilled in the art, and would be somewhat dependent upon the susceptibility of a given tower to being struck by lightning, and by the voltage being conveyed through the electric power lines.
Both the core and the sheath of the shielded conductor may coaxially extend downwardly to a position adjacent the ground at the bottom of the tower, and the core and the sheath may be grounded separately or jointly to the surface of the earth.
11~4637 The tower itself might be grounded, and the ground connection of the tower may form the ground connection for one or both of the core and the sheath.
Further, the sheath may end at a position spaced above the ~round, it being understood that the bottom end of the sheath extends below the lowermost electric power line by a distance at least sufficient to exclude the occurrence of a secondary arc discharge between the core and the lowermost electric power line. In this instance, the core may extend to the surface of the ground and thereat be grounded, or alternatively the core may be connected to the ground by a conductor which extends between the lower end of the core and the surface of the ground. In such case the sheath would be electrically connected to the core, or if the tower is a metal tower and is grounded, the lower end of the sheath may be electrically connected to the tower.
Further alternatively, both the lower end of the sheath and the lower end of the core may end at a position spaced above the surface of the ground, again as long as the lower end of the sheath is spaced below the lowermost electric power line by a distance sufficient to exclude a secondary arc discharge between the core and the lowermost electric power line. In this case, the tower must be conducting, such as a metal tower, and the tower most be grounded. Further, the lower end of the core and the lower end of the sheath must be electrically connected to the metal tower. Alternatively, the lower end of the sheath could be electrically connected to the lower end of the core, and the lower end of the core would be _ electrically connected to the tower.
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Although the fundamental object of the present invention is to protect the electric power lines from a secondary arc discharge, it will further be apparent that . in certain instances the arrangement of the present invention will also protect the tower itself from being struck by lightning. For example, when the tower is not : conducting, for example when it is formed of a material such as reinforced concrete, then the coaxial shielded cable may extend from the upper conducting member entirely .
to ~round. Such an arrangement wiil operate to reduce the risk of the tower itself being struck by lightning.
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-- ~104637 BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments thereof, taken with the accompanying drawings, wherein:
Figure 1 is a schematic view of a high voltage tower equipped with a lightning arrester in accordance with a first embodiment of the present invention, wherein the entire coaxial shielded cable extends to the ground;
Figure 2 is an enlarged partial view of the ground connection of the coaxial shielded cable of Figure-l;
~ Figure 3 is an enlarged view illustrating one manner - of connection of an upper protection conducting wire and the conducting core of the coaxial shielded cable of Figure 1.
Figure 4 is a cross-sectional view through one arrange-ment of a coaxial shielded cable which may be employed in the present invention;
Figure 5 (see the sheet containing Figure 1) is a ,i schematic view of a second embodiment of the present invention, . .
~` wherein the sheath does not extend entirely to ground and wherein ..
,~ 20 the core is extended to ground by a conductor;
Figure 6 is a schematic view of a third embodiment of the present invention, wherein both the lower end of the core and the lower end of the sheath terminate above the surface of the ground and are grounded by electrical connection to a metal grounded tower; and X
11~34~3'^~
- - Figu~e 7 is a partial schematic view-of an arran~eMent of the present invention wherein the tower does not include an upper protection conducting wi:re, but wherein the coaxial shielded cable is connected to a metal member such as a lightning rod located at the top of the tower.
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11~4637 DETAILED DESCR:rPTION OF THE I~VENTION
: _-With reference now to Figure 1 of the drawings, there is shown a first embodiment of the present invention.
Specifically, there is shown a metal tower 1, of conventional construction, supporting a plurality of electric power lines 4 by means of insulators in a conventional manner. Tower 1 also supports at the top thereof a conventional protection conducting wire 2 by means of an insulator 3. In the drawings there are shown three electric power lines 4 being s 10 supported, However, it is to be understood that the towers could support a lesser or greater number of electric power lines as would be understood by those skilled in the art.
The novel lightning arrester or lightning protection system of the present invention involves a coaxial shielded conductor or cable 20 which extends along the tower. In Figure 1, the cable 20 extends along an edge of the tower, but it should be understood that the cable 20 could be otherwise supported along the tower, for example along the axis of the tower.
The coaxial shielded cable 20 includes a central conductor core 30 coaxially surrounded by an outer conducting sheath, with a layer of insulating material between and electrically separating the core 30 and the sheath 40. The upper end of core 30 is electrically 2~ connected to protection conducting wire 2. The upper end of sheath 40 is not electrically connected to line 2 or to the core 30. In the embodiment of Figure 1, the entire . , .
11~4~i37 coaxial shielded cable 20, i,e. both the core 30 and the sheath 40, extends along the entire length of the tower to the surface of the ground whereat both the lower end of the core and the lower end of the sheath are grounded.
In Figure 2 there is shown in more detail.how the lower ends of the core 30 and the sheath 40 are grounded. Specifically, Figure 2 shows that core 30 is grounded separately from sheath 40 which has its own ground connection 25. It is however to be understood that both core 30 and sheath 40 could be jointly grounded by a single ground connection.
Figure 3 shows that electrical connection between core 30 and protection conaucting wire 2 is achieved by means of a clamp 21 which is operated, for example by bolts, to clamp conducting members 2 and 30 together. It will however be understood that the electrical sonnection between core 30 and wire 2 could be achieved by different means as would be apparent to those skilled in the art. For example, the core 30 could be connected to the protection conducting wire 2 by means of two conducting strands or wires, one on each side of insulator 3. Even further, the upper end of the coaxial `1 shielded cable could be combined with insulator 3, and , the upper end of core 30 could pass through the center -~ 25 of insulator 3 and be electrically connected to wire 2.
Other possible connecting modifications will he apparent to those sXilled in the art.
~12-, , .
Figure 4 shows a cross-section through a preferred arrangement of the coaxial shielded conductor or cable 20 in accoraance with the above mentioned U,S. Patent No. 3,919,956.
Specifically, cable 20 includes a central conductor core 30 which is coaxially surrounded by an outer conducting sheath 40.
Central conductor core 30 includes a central element 32 formed of an insulating material coaxially surrounded by a plurality of metal conducting wires 31, thus forming a hollow coaxial . central conductor. Outer sheath 40, which forms an electrical shield around core 30, is formed of a plurality of metal wires 41 which are coaxially surrounded by a layer of insulating material 42. Sheath 40 is coaxially separated from core 30 by means of a layer of insulating material 43. The purpose of the conductor core 30 is to pass the current from a lightning 1~ charge to ground, while the purpose of the sheath 40, and insulating layer 43, is to form a coaxial shield which is capable of protecting electric power lines 4 from a secondar~
aXc discharge from core 30. That is, sheath 40 and insulating layer 43 operate to protect the surrounding environment, particularly electric power lines 4, from the lightning charge which from time to time will pass through core 30. Inversely, sheath 40 and insulating layer 43 operate to form a shield which protects core 30 against potential influences of the surrounding environment.
11~4ti37 The arrangement of coaxial shielded cable 20 shown in Figure 4 is a preferred configuration. The specific materials and sizes of the various ele~ents and portions of cable 20 may be as disclosed in U,S. Patent No. 3,919,956, or may be altered as will be apparent to those skilled in the art to achieve the desired protection capabilities discussed herein. Further, the specific configuration of the cable 20 may be other than is disclosed in Figure 4, as long as the cable includes a central conductor core, an outer conducting sheath coaxially surrounding the core, and an insulating layer separating the core from the sheath, and as long as the cable operates in the desired manner disclosed herein.
It has been found that the type of coaxial shielded conductor or cable described above possesses the capability of absorbing the discharge from lightning and channeling such lightning to ground without any interference, i.e.
specifically without any secondary arc discharge, to the electric power lines.
Although the tower shown in Figure 1 is a metal tower which itself is grounded, it is to be understood that in accordance with the present invention the tower itself eould be formed of a non-conducting material, for example eoncrete or reinforced concrete. Such an arrangement would thereby make the tower itself less susceptible to being struck by lightning.
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11~4637 As noted above, however, the fundamental purpose of the present invention is to protect the electric power lines 4 from a secondary arc discharge. Accordingly, in accordance with further features of the present inventicn, when the tower 1 is itself formed of a conducting material, such as metal, and when the tower is itself grounded, it is possible to terminate the coaxial shielded cable 20 at a position above the surface of the ground and to then conduct , the current from a lightning discharge from such point to ¦ 10 the earth, either through the tower itself or through a ¦ special conductor.
Such arrangements will be discussed below with regard to Figures 5 and 6. It is however to specifically be , understood that in these embodiments of the present invention the shielded cable 20, and specifically the outer sheath 40, must extend below the lowermost electric power line 4 by a distance which is at least sufficient to exclude the possibility of a secondary arc discharge between the core 30 and any of the electric power lines 4. As discussed above, the determination of such distance would be readily possible to one ordinarily skilled in the art, depending upon the particular parameters involved in a given installation.
¦ In t~e embodiment of Figure 5, at least the sheath 40 terminates at a position spaced above the surface of the ! ` ground In the embodiment specifically illustrated in Figure 5, the entire cable 20 terminates at such position spaced above the surface of the ground, a clamp 22 electrically ' -15-' .
connects the lower end of sheath 40 to the metal frame of . .. ..
tower 1, and a conductor 23 extends from the lower end of core to a ground connection 24, Thus, the lower end of core 30 is grounded by conductor 23 and ground connection 24, while the lower end of sheath 40 is grounded by the metal tower 1 and the ground connection 5 of tower 1. It would be possible however, for conductGr 23 to be replaced by an extension of the core 30 itself. Further, the lower end of sheath 40 could be electrically connected to the lower end of core 30 or to conductor 23. Such an arrangement would be employable in a situation wherein tower 1 is not formed of a conducting material such as metal. Further in such an alternative arrangement, the lower end of sheath 40 could be grounded by a separate conductor similar to conductor 23.
In the arrangement shown in Figure 6, tower 1 is formed of a conducting material such as metal and is grounded by a ground connection 5. Both the lower end of sheath 40 and the lower end of core 30 terminate at a position spaced above the surface of the ground. The lower end of sheath 40 is electrically connected to the metal frame of tower 1 by a clamp 22, and the lower end of core 30 is electrically connected to the metal frame of tower 1 by a clamp 26. Thus, the lower ends of both the core and the sheath are grounded by tower 1 and ground connection 5. In this embodiment of the present invention, it would also be possible to electrically connect the lower end of sheath 40 to core 30.
~ , . '' ' '' 11( )4637 i In all of tne aDove discussed embodiments of the .¦ present invention, the upper conducting member to which the ¦' upper end of the core is attached is shown in the form of a protection conducting wire 2, However, it is to be under-stood that the novel concept of the present invention is I applicable to electric power line tower arrangements wherein ¦ no such protection conducting wire 2 is provided.
Specifically, as shown schematically in Figure 7 wherein there is not provided a protection conducting wire 2, the upper end of core 30 of cable 20 is electrically connected to an upper conducting portion 7, for example formed of a metal conducting material, of tower 1. In the specifically illustrated arrangement of Figure 7, the upper end of core 30 is shown as being electrically connected to a conventional lightning rod. It is however to be understood that the upper end of core 30 could be connected to a plurality of such conventional lightning rods. Further, the upper end of core 30 could be connected to any other top , portion of tower 1 which is formed of a conducting material, such as metal. It is specifically to be understood that the remaining features of the alternative embodiment of Figure 7 would be as discussed above with regard to the structural arrangements shown in Figures 1 through 6 of the drawings.
' It will be apparent from the above discussion that by the arrangement of the present invention, it is possible to prevent interference with or damage to the aerial electric power lines 4 upon the occurrence of the tower being struck by lightning. Specifically, the cable 20 extends below the ,~ ' ~
, 11(~4637 lowermost eiectric power line 4 at least by a distance -sufficient to exclude the occurrence of a secondary arc discharge between core 30 and any of the electric power lines. The outer coaxial conducting sheath 40 provides . S a shield which coaxially surrounds the lightning discharge . which is being grounded by the core 30.
. It will further be apparent that although the . above description is directed to specific and preferred . structural embodiments of the present invention, such specific structural arrangements are intended to be . exemplary only, and not limiting to the scope of the ~ present invention, since various modifications may be : made to the above specifically described and illustrated . arrangements without departing from the scope of the present invention.
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SUMMARY ` OF THE INVENTION ~ 4t;37 With the above discussion in mind, it is the principal object of the present invention to provide an improved lightning arrester system or system from protecting against a lightning 'discharge aerial electric power lines supported abo~e the ground by towers.
It is a further object of the present invention to provide such a system which for practical purposes avoids the risk, not only of lightning striking the electric power lines, but which also avoids the risk of a secondary arc discharge between the system and the electric power lines.
These objects are achieved in accordance with the present invention by the provision of a shielded conductor including a central conductor core, an outer conducting sheath, and an insulating layer between the core and the sheath. The upper end of the core is electrically connected to a conducting member adjacent the top of the tower which supports the electric power lines above the ground. Both the lower end of the core and the lower end of the sheath are grounded. The sheath extends from substantially the area of connection of the core to the conducting member to a position bel~w the power line, with the lower end of the sheath being spaced below the power line at least by a distance sufficient to exclude the formation of a secondary arc discharge between the core and the power line.
The coaxial shielded cable may ~e employed on all of the towers which support the aerial electric power lines.
However, such arrangement is not necessary, as long as those towers which are most susceptible and exposed to lightning are each provided with a coaxial shielded cable. Those skilled in the art would be readily able to determine which towers are most exposed to lightning merely by studying historical statistics of a given power line system or similar power line systems. Normally, lightning discharges occur most frequently on hills or where the tower is located in wet or marshy ground.
The coaxial shielded cable which is employed as a lightning arrester or as a system for protecting the electric power lines from lightning di~charge may be the coaxial shielded cable ~isclosed in the above mentioned U.S. Patent No. 3,919,956, or may be any other similar coaxial shielded cable which includes a central conductor core, an outer conducting sheath coaxially surrounding the central conductor core, and an insulating layer between the central core and the outer sheath.
The upper end of the core is electrically connected to a conducting member positioned adjacent the top of the tower. Such conducting member may be a conventional protectiGn conductor wire supported by and extending along the towers at a position above the aerial electric power lines. Alternatively, the conducting member may be one or more conventional lightning rods located at the top of the tower. Further, the conducting member may be a metal portion on the top of the tower. The upper end of the outer coaxial sheath is not electrically connected to the conducting member or to the central core.
111~4~37 Both the lower end of the core and the lower end of the sheath are grounded, The upper end of the sheath is located adjacent the area of connection of the core to the conducting member. The sheath must extend downwardly to a position below the lowermost electriC power line such ~hat the lower end of the sheath is spaced below the lowermost electric power line at least by a distance sufficient to exclude or prevent the formation of a secondary arc discharge between the core and any of the electric power lines. Thusl the outer conducting sheath, which is insulated from the central conductor core, acts as a shield to prevent a secondary arc discharge from the core which operates to ground a lightning discharge striking the conducting member and any of the electric power lines. The 1~ distance by which the lower end of the sheath must be spaced from the lowermost electric power line to prevent such secondary arc discharge would be readily determinable by one skilled in the art, and would be somewhat dependent upon the susceptibility of a given tower to being struck by lightning, and by the voltage being conveyed through the electric power lines.
Both the core and the sheath of the shielded conductor may coaxially extend downwardly to a position adjacent the ground at the bottom of the tower, and the core and the sheath may be grounded separately or jointly to the surface of the earth.
11~4637 The tower itself might be grounded, and the ground connection of the tower may form the ground connection for one or both of the core and the sheath.
Further, the sheath may end at a position spaced above the ~round, it being understood that the bottom end of the sheath extends below the lowermost electric power line by a distance at least sufficient to exclude the occurrence of a secondary arc discharge between the core and the lowermost electric power line. In this instance, the core may extend to the surface of the ground and thereat be grounded, or alternatively the core may be connected to the ground by a conductor which extends between the lower end of the core and the surface of the ground. In such case the sheath would be electrically connected to the core, or if the tower is a metal tower and is grounded, the lower end of the sheath may be electrically connected to the tower.
Further alternatively, both the lower end of the sheath and the lower end of the core may end at a position spaced above the surface of the ground, again as long as the lower end of the sheath is spaced below the lowermost electric power line by a distance sufficient to exclude a secondary arc discharge between the core and the lowermost electric power line. In this case, the tower must be conducting, such as a metal tower, and the tower most be grounded. Further, the lower end of the core and the lower end of the sheath must be electrically connected to the metal tower. Alternatively, the lower end of the sheath could be electrically connected to the lower end of the core, and the lower end of the core would be _ electrically connected to the tower.
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Although the fundamental object of the present invention is to protect the electric power lines from a secondary arc discharge, it will further be apparent that . in certain instances the arrangement of the present invention will also protect the tower itself from being struck by lightning. For example, when the tower is not : conducting, for example when it is formed of a material such as reinforced concrete, then the coaxial shielded cable may extend from the upper conducting member entirely .
to ~round. Such an arrangement wiil operate to reduce the risk of the tower itself being struck by lightning.
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~. ..
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. .
-- ~104637 BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments thereof, taken with the accompanying drawings, wherein:
Figure 1 is a schematic view of a high voltage tower equipped with a lightning arrester in accordance with a first embodiment of the present invention, wherein the entire coaxial shielded cable extends to the ground;
Figure 2 is an enlarged partial view of the ground connection of the coaxial shielded cable of Figure-l;
~ Figure 3 is an enlarged view illustrating one manner - of connection of an upper protection conducting wire and the conducting core of the coaxial shielded cable of Figure 1.
Figure 4 is a cross-sectional view through one arrange-ment of a coaxial shielded cable which may be employed in the present invention;
Figure 5 (see the sheet containing Figure 1) is a ,i schematic view of a second embodiment of the present invention, . .
~` wherein the sheath does not extend entirely to ground and wherein ..
,~ 20 the core is extended to ground by a conductor;
Figure 6 is a schematic view of a third embodiment of the present invention, wherein both the lower end of the core and the lower end of the sheath terminate above the surface of the ground and are grounded by electrical connection to a metal grounded tower; and X
11~34~3'^~
- - Figu~e 7 is a partial schematic view-of an arran~eMent of the present invention wherein the tower does not include an upper protection conducting wi:re, but wherein the coaxial shielded cable is connected to a metal member such as a lightning rod located at the top of the tower.
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11~4637 DETAILED DESCR:rPTION OF THE I~VENTION
: _-With reference now to Figure 1 of the drawings, there is shown a first embodiment of the present invention.
Specifically, there is shown a metal tower 1, of conventional construction, supporting a plurality of electric power lines 4 by means of insulators in a conventional manner. Tower 1 also supports at the top thereof a conventional protection conducting wire 2 by means of an insulator 3. In the drawings there are shown three electric power lines 4 being s 10 supported, However, it is to be understood that the towers could support a lesser or greater number of electric power lines as would be understood by those skilled in the art.
The novel lightning arrester or lightning protection system of the present invention involves a coaxial shielded conductor or cable 20 which extends along the tower. In Figure 1, the cable 20 extends along an edge of the tower, but it should be understood that the cable 20 could be otherwise supported along the tower, for example along the axis of the tower.
The coaxial shielded cable 20 includes a central conductor core 30 coaxially surrounded by an outer conducting sheath, with a layer of insulating material between and electrically separating the core 30 and the sheath 40. The upper end of core 30 is electrically 2~ connected to protection conducting wire 2. The upper end of sheath 40 is not electrically connected to line 2 or to the core 30. In the embodiment of Figure 1, the entire . , .
11~4~i37 coaxial shielded cable 20, i,e. both the core 30 and the sheath 40, extends along the entire length of the tower to the surface of the ground whereat both the lower end of the core and the lower end of the sheath are grounded.
In Figure 2 there is shown in more detail.how the lower ends of the core 30 and the sheath 40 are grounded. Specifically, Figure 2 shows that core 30 is grounded separately from sheath 40 which has its own ground connection 25. It is however to be understood that both core 30 and sheath 40 could be jointly grounded by a single ground connection.
Figure 3 shows that electrical connection between core 30 and protection conaucting wire 2 is achieved by means of a clamp 21 which is operated, for example by bolts, to clamp conducting members 2 and 30 together. It will however be understood that the electrical sonnection between core 30 and wire 2 could be achieved by different means as would be apparent to those skilled in the art. For example, the core 30 could be connected to the protection conducting wire 2 by means of two conducting strands or wires, one on each side of insulator 3. Even further, the upper end of the coaxial `1 shielded cable could be combined with insulator 3, and , the upper end of core 30 could pass through the center -~ 25 of insulator 3 and be electrically connected to wire 2.
Other possible connecting modifications will he apparent to those sXilled in the art.
~12-, , .
Figure 4 shows a cross-section through a preferred arrangement of the coaxial shielded conductor or cable 20 in accoraance with the above mentioned U,S. Patent No. 3,919,956.
Specifically, cable 20 includes a central conductor core 30 which is coaxially surrounded by an outer conducting sheath 40.
Central conductor core 30 includes a central element 32 formed of an insulating material coaxially surrounded by a plurality of metal conducting wires 31, thus forming a hollow coaxial . central conductor. Outer sheath 40, which forms an electrical shield around core 30, is formed of a plurality of metal wires 41 which are coaxially surrounded by a layer of insulating material 42. Sheath 40 is coaxially separated from core 30 by means of a layer of insulating material 43. The purpose of the conductor core 30 is to pass the current from a lightning 1~ charge to ground, while the purpose of the sheath 40, and insulating layer 43, is to form a coaxial shield which is capable of protecting electric power lines 4 from a secondar~
aXc discharge from core 30. That is, sheath 40 and insulating layer 43 operate to protect the surrounding environment, particularly electric power lines 4, from the lightning charge which from time to time will pass through core 30. Inversely, sheath 40 and insulating layer 43 operate to form a shield which protects core 30 against potential influences of the surrounding environment.
11~4ti37 The arrangement of coaxial shielded cable 20 shown in Figure 4 is a preferred configuration. The specific materials and sizes of the various ele~ents and portions of cable 20 may be as disclosed in U,S. Patent No. 3,919,956, or may be altered as will be apparent to those skilled in the art to achieve the desired protection capabilities discussed herein. Further, the specific configuration of the cable 20 may be other than is disclosed in Figure 4, as long as the cable includes a central conductor core, an outer conducting sheath coaxially surrounding the core, and an insulating layer separating the core from the sheath, and as long as the cable operates in the desired manner disclosed herein.
It has been found that the type of coaxial shielded conductor or cable described above possesses the capability of absorbing the discharge from lightning and channeling such lightning to ground without any interference, i.e.
specifically without any secondary arc discharge, to the electric power lines.
Although the tower shown in Figure 1 is a metal tower which itself is grounded, it is to be understood that in accordance with the present invention the tower itself eould be formed of a non-conducting material, for example eoncrete or reinforced concrete. Such an arrangement would thereby make the tower itself less susceptible to being struck by lightning.
. .- '' .
11~4637 As noted above, however, the fundamental purpose of the present invention is to protect the electric power lines 4 from a secondary arc discharge. Accordingly, in accordance with further features of the present inventicn, when the tower 1 is itself formed of a conducting material, such as metal, and when the tower is itself grounded, it is possible to terminate the coaxial shielded cable 20 at a position above the surface of the ground and to then conduct , the current from a lightning discharge from such point to ¦ 10 the earth, either through the tower itself or through a ¦ special conductor.
Such arrangements will be discussed below with regard to Figures 5 and 6. It is however to specifically be , understood that in these embodiments of the present invention the shielded cable 20, and specifically the outer sheath 40, must extend below the lowermost electric power line 4 by a distance which is at least sufficient to exclude the possibility of a secondary arc discharge between the core 30 and any of the electric power lines 4. As discussed above, the determination of such distance would be readily possible to one ordinarily skilled in the art, depending upon the particular parameters involved in a given installation.
¦ In t~e embodiment of Figure 5, at least the sheath 40 terminates at a position spaced above the surface of the ! ` ground In the embodiment specifically illustrated in Figure 5, the entire cable 20 terminates at such position spaced above the surface of the ground, a clamp 22 electrically ' -15-' .
connects the lower end of sheath 40 to the metal frame of . .. ..
tower 1, and a conductor 23 extends from the lower end of core to a ground connection 24, Thus, the lower end of core 30 is grounded by conductor 23 and ground connection 24, while the lower end of sheath 40 is grounded by the metal tower 1 and the ground connection 5 of tower 1. It would be possible however, for conductGr 23 to be replaced by an extension of the core 30 itself. Further, the lower end of sheath 40 could be electrically connected to the lower end of core 30 or to conductor 23. Such an arrangement would be employable in a situation wherein tower 1 is not formed of a conducting material such as metal. Further in such an alternative arrangement, the lower end of sheath 40 could be grounded by a separate conductor similar to conductor 23.
In the arrangement shown in Figure 6, tower 1 is formed of a conducting material such as metal and is grounded by a ground connection 5. Both the lower end of sheath 40 and the lower end of core 30 terminate at a position spaced above the surface of the ground. The lower end of sheath 40 is electrically connected to the metal frame of tower 1 by a clamp 22, and the lower end of core 30 is electrically connected to the metal frame of tower 1 by a clamp 26. Thus, the lower ends of both the core and the sheath are grounded by tower 1 and ground connection 5. In this embodiment of the present invention, it would also be possible to electrically connect the lower end of sheath 40 to core 30.
~ , . '' ' '' 11( )4637 i In all of tne aDove discussed embodiments of the .¦ present invention, the upper conducting member to which the ¦' upper end of the core is attached is shown in the form of a protection conducting wire 2, However, it is to be under-stood that the novel concept of the present invention is I applicable to electric power line tower arrangements wherein ¦ no such protection conducting wire 2 is provided.
Specifically, as shown schematically in Figure 7 wherein there is not provided a protection conducting wire 2, the upper end of core 30 of cable 20 is electrically connected to an upper conducting portion 7, for example formed of a metal conducting material, of tower 1. In the specifically illustrated arrangement of Figure 7, the upper end of core 30 is shown as being electrically connected to a conventional lightning rod. It is however to be understood that the upper end of core 30 could be connected to a plurality of such conventional lightning rods. Further, the upper end of core 30 could be connected to any other top , portion of tower 1 which is formed of a conducting material, such as metal. It is specifically to be understood that the remaining features of the alternative embodiment of Figure 7 would be as discussed above with regard to the structural arrangements shown in Figures 1 through 6 of the drawings.
' It will be apparent from the above discussion that by the arrangement of the present invention, it is possible to prevent interference with or damage to the aerial electric power lines 4 upon the occurrence of the tower being struck by lightning. Specifically, the cable 20 extends below the ,~ ' ~
, 11(~4637 lowermost eiectric power line 4 at least by a distance -sufficient to exclude the occurrence of a secondary arc discharge between core 30 and any of the electric power lines. The outer coaxial conducting sheath 40 provides . S a shield which coaxially surrounds the lightning discharge . which is being grounded by the core 30.
. It will further be apparent that although the . above description is directed to specific and preferred . structural embodiments of the present invention, such specific structural arrangements are intended to be . exemplary only, and not limiting to the scope of the ~ present invention, since various modifications may be : made to the above specifically described and illustrated . arrangements without departing from the scope of the present invention.
, '~
. ,, 1, -~.
' `
-~8-.
Claims (16)
1. In a tower extending above the ground and supporting at least one aerial electric power line, and means for protecting said power line from a lightning discharge, the improvement wherein said protecting means comprises:
a shielded conductor including a central conductor core, an outer conducting sheath, and an insulating layer between said core and said sheath;
the upper end of said core being electrically connected to a conducting member adjacent the top of said tower;
both the lower end of said core and the lower end of said sheath being grounded; and said sheath extending from substantially the area of connection of said core to said conducting member to a position below said power line, said position being spaced below said power line at least by a distance sufficient to exclude the formation of a discharge arc between said core and said power line.
a shielded conductor including a central conductor core, an outer conducting sheath, and an insulating layer between said core and said sheath;
the upper end of said core being electrically connected to a conducting member adjacent the top of said tower;
both the lower end of said core and the lower end of said sheath being grounded; and said sheath extending from substantially the area of connection of said core to said conducting member to a position below said power line, said position being spaced below said power line at least by a distance sufficient to exclude the formation of a discharge arc between said core and said power line.
2. The improvement claimed in claim 1, wherein the upper end of said sheath is free of electrical connection to said conducting member.
3. The improvement claimed in claim 1, further comprising a plurality of towers supporting said at least one power line, at least those towers most exposed to lightning each having a separate said improved protecting means.
4. The improvement claimed in claim 1, wherein said conducting member comprises a protection conductor wire arranged at the top of said tower at a position above said power line, said core being electrically connected to said wire.
5. The improvement claimed in claim 1, wherein said conducting member comprises at least one lightning rod arranged at the top of said tower at a position above said power line, said core being electrically connected to said lightning rod.
6. The improvement claimed in claim 1, wherein said conducting member comprises a metal-portion of the top of said tower at a position above said power line, said core being electrically connected to said metal portion.
7. The improvement claimed in claim 1, wherein both said core and said sheath of said shielded conductor extend downwardly to a position adjacent the ground at the bottom of said tower, both said core and said sheath being grounded to the surface of the earth.
8. The improvement claimed in claim 7, wherein said core and said sheath are-grounded separately.
9. The improvement claimed in claim 7, wherein said core and said sheath are jointly grounded.
10, The improvement claimed in claim 1, wherein said tower is grounded, and the ground connection of said tower forms the ground connection for at least one of said core and said sheath.
11, The improvement claimed in claim 1, wherein at least said sheath of said shielded conductor ends at a position spaced above the ground.
12. The improvement claimed in claim 11, wherein said core ends at a position spaced above the ground.
13. The improvement claimed in claim 12, further comprising a conductor extending from the lower end of said core to the ground, said conductor being grounded.
14. The improvement claimed in claim 13, wherein the lower end of said sheath is electrically connected to said core.
15. The improvement claimed in claim 13, wherein said tower comprises a metal tower, the lower end of said sheath is electrically connected to said tower, and said tower is grounded,
16. The improvement claimed in claim 12, wherein said tower comprises a metal tower, the lower end of said sheath is electrically connected to said tower, the lower end of said core is electrically connected to said tower, and said tower is grounded.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH1237/78 | 1978-02-03 | ||
| CH123778A CH620059A5 (en) | 1978-02-03 | 1978-02-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1104637A true CA1104637A (en) | 1981-07-07 |
Family
ID=4205678
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA319,875A Expired CA1104637A (en) | 1978-02-03 | 1979-01-18 | Lightning arrester for aerial electric power lines |
Country Status (18)
| Country | Link |
|---|---|
| JP (1) | JPS54119693A (en) |
| AR (1) | AR216364A1 (en) |
| AU (1) | AU4384179A (en) |
| BE (1) | BE873829A (en) |
| BR (1) | BR7900631A (en) |
| CA (1) | CA1104637A (en) |
| CH (1) | CH620059A5 (en) |
| DE (1) | DE2902762A1 (en) |
| EG (1) | EG13360A (en) |
| ES (1) | ES477372A1 (en) |
| FR (1) | FR2416578A1 (en) |
| GB (1) | GB2013998A (en) |
| GR (1) | GR63067B (en) |
| IN (1) | IN151211B (en) |
| IT (1) | IT1114365B (en) |
| MX (1) | MX146154A (en) |
| PT (1) | PT69162A (en) |
| ZA (1) | ZA79439B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947097A (en) * | 2017-12-06 | 2018-04-20 | 国家电网公司 | A kind of 10kV suspended insulated guide wires with the anti-lightning strike broken string of shielded layer |
| CN108462140A (en) * | 2018-03-27 | 2018-08-28 | 国网冀北电力有限公司承德供电公司 | A kind of thunder resisting equipment of transmission line of electricity |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58216396A (en) * | 1982-06-10 | 1983-12-16 | 関西電力株式会社 | Lightning grounding device |
| FR2570548B1 (en) * | 1984-09-18 | 1987-07-10 | Schaff Jean Paul | IMPROVED ELECTRICAL JUNCTION DEVICE FOR SURGE PROTECTION INSTALLATIONS |
| JPS61164414A (en) * | 1985-01-12 | 1986-07-25 | 白川電気土木株式会社 | Lightning method of transmission line |
| CH669482A5 (en) * | 1986-11-01 | 1989-03-15 | Energie Froide Int Sa | |
| JPH0615466Y2 (en) * | 1987-09-04 | 1994-04-20 | 三菱電線工業株式会社 | Overhead section of overhead tower with built-in optical fiber |
| JPH01122316A (en) * | 1987-11-05 | 1989-05-15 | Furukawa Electric Co Ltd:The | Aerial transmission line |
| JP2834357B2 (en) * | 1992-01-16 | 1998-12-09 | 中部電力株式会社 | Lightning protection devices in distribution lines |
| US5365398A (en) * | 1992-07-24 | 1994-11-15 | Richard Briet | Lightning protection system |
| IT1295342B1 (en) * | 1997-10-15 | 1999-05-12 | Abb Research Ltd | POLE FOR AIR LINES OF ELECTRICITY TRANSMISSION |
| JP4359002B2 (en) * | 2001-03-13 | 2009-11-04 | 株式会社かんでんエンジニアリング | Lightning protection structure of building |
| CN100428601C (en) * | 2005-10-12 | 2008-10-22 | 江苏省电力公司扬州供电公司 | Lightning-inductive shielding line for 10KV overhead insulated conducting wire for preventing thunderstrike breakage |
| WO2016128619A1 (en) * | 2015-02-13 | 2016-08-18 | Viitamäki Sakari | Arrangement for protecting power line |
| CN105826892B (en) * | 2016-05-23 | 2018-03-02 | 西安交通大学 | For reducing the shielding line system of mountain area 750kV common-tower double-circuit lines shielding exposure arc |
| CN214887020U (en) | 2021-04-07 | 2021-11-26 | 烟台杰瑞石油装备技术有限公司 | Fracturing wellsite system |
-
1978
- 1978-02-03 CH CH123778A patent/CH620059A5/fr not_active IP Right Cessation
-
1979
- 1979-01-18 CA CA319,875A patent/CA1104637A/en not_active Expired
- 1979-01-24 IT IT47752/79A patent/IT1114365B/en active
- 1979-01-25 DE DE19792902762 patent/DE2902762A1/en not_active Withdrawn
- 1979-01-27 IN IN059/DEL/79A patent/IN151211B/en unknown
- 1979-01-29 FR FR7902233A patent/FR2416578A1/en active Granted
- 1979-01-29 GB GB7903029A patent/GB2013998A/en not_active Withdrawn
- 1979-01-31 GR GR58226A patent/GR63067B/en unknown
- 1979-01-31 PT PT7969162A patent/PT69162A/en unknown
- 1979-01-31 EG EG66/79A patent/EG13360A/en active
- 1979-01-31 BE BE193176A patent/BE873829A/en not_active IP Right Cessation
- 1979-02-01 JP JP1096579A patent/JPS54119693A/en active Pending
- 1979-02-01 AR AR275375A patent/AR216364A1/en active
- 1979-02-01 BR BR7900631A patent/BR7900631A/en unknown
- 1979-02-01 AU AU43841/79A patent/AU4384179A/en not_active Abandoned
- 1979-02-01 ES ES477372A patent/ES477372A1/en not_active Expired
- 1979-02-02 ZA ZA79439A patent/ZA79439B/en unknown
- 1979-02-02 MX MX176488A patent/MX146154A/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947097A (en) * | 2017-12-06 | 2018-04-20 | 国家电网公司 | A kind of 10kV suspended insulated guide wires with the anti-lightning strike broken string of shielded layer |
| CN108462140A (en) * | 2018-03-27 | 2018-08-28 | 国网冀北电力有限公司承德供电公司 | A kind of thunder resisting equipment of transmission line of electricity |
Also Published As
| Publication number | Publication date |
|---|---|
| IN151211B (en) | 1983-03-12 |
| BR7900631A (en) | 1979-08-28 |
| MX146154A (en) | 1982-05-19 |
| PT69162A (en) | 1979-02-01 |
| CH620059A5 (en) | 1980-10-31 |
| EG13360A (en) | 1981-06-30 |
| BE873829A (en) | 1979-05-16 |
| GB2013998A (en) | 1979-08-15 |
| AU4384179A (en) | 1979-08-09 |
| DE2902762A1 (en) | 1979-08-09 |
| JPS54119693A (en) | 1979-09-17 |
| FR2416578A1 (en) | 1979-08-31 |
| ZA79439B (en) | 1980-02-27 |
| GR63067B (en) | 1979-08-06 |
| ES477372A1 (en) | 1979-12-16 |
| FR2416578B3 (en) | 1981-10-30 |
| IT1114365B (en) | 1986-01-27 |
| AR216364A1 (en) | 1979-12-14 |
| IT7947752A0 (en) | 1979-01-24 |
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Legal Events
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| MKEX | Expiry |