CA1232599A - Stringing overhead flexible electric conductors - Google Patents
Stringing overhead flexible electric conductorsInfo
- Publication number
- CA1232599A CA1232599A CA000490269A CA490269A CA1232599A CA 1232599 A CA1232599 A CA 1232599A CA 000490269 A CA000490269 A CA 000490269A CA 490269 A CA490269 A CA 490269A CA 1232599 A CA1232599 A CA 1232599A
- Authority
- CA
- Canada
- Prior art keywords
- flexible
- elongate
- conductor
- elongate member
- counterweight
- 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
-
- 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
- H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
- H02G1/02—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for overhead lines or cables
- H02G1/04—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for overhead lines or cables for mounting or stretching
Landscapes
- Suspension Of Electric Lines Or Cables (AREA)
Abstract
ABSTRACT
To prevent unacceptable untwisting of the outer helically wound wires of an overhead electric conductor whilst it is being strung under tension between towers, a flexible weighted device is connected between the leading end of the conductor and the trailing end of a flexible pulling line. This device comprises a flexible elongate member built up of at least three flexible rods connected end-to-end, each of which rods has freely pivotally connected to one of its ends an elongate counterweight having a transverse cross-section of substantially C-shape. When tension is applied to the flexible line to draw the conductor into position and before the conductor is secured to dead end clamps, each elongate counterweight will be suspended downwardly from the flexible rod solely under the action of its weight to prevent unacceptable untwisting of the wires and, as the flexible elongate member is drawn through a stringing block, each elongate counterweight in turn will be caused to pivot upwardly to lie alongside, and pass through the stringing block with, its associated flexible rod.
To prevent unacceptable untwisting of the outer helically wound wires of an overhead electric conductor whilst it is being strung under tension between towers, a flexible weighted device is connected between the leading end of the conductor and the trailing end of a flexible pulling line. This device comprises a flexible elongate member built up of at least three flexible rods connected end-to-end, each of which rods has freely pivotally connected to one of its ends an elongate counterweight having a transverse cross-section of substantially C-shape. When tension is applied to the flexible line to draw the conductor into position and before the conductor is secured to dead end clamps, each elongate counterweight will be suspended downwardly from the flexible rod solely under the action of its weight to prevent unacceptable untwisting of the wires and, as the flexible elongate member is drawn through a stringing block, each elongate counterweight in turn will be caused to pivot upwardly to lie alongside, and pass through the stringing block with, its associated flexible rod.
Description
~3;~5~9 Stringing Overhead Flexibie Electric Conductors This invention relates to overhead electric transmission and distribution systems ox the kind in which at least one overhead flexible electric conductor is suspended in long lengths between towers, pylons, poles or other upstanding supports at spaced positions along the length ox the conductor.
The invention is especially, but not exclusively, concerned with overhead electric and optical transmission and distribution systems of the kind in which the overhead flexible electric conductor or at least one ox the overhead flexible electric conductors includes at least one flexible optical guide. One sueh overhead flexible electric conductor i9 described and claimed in British Patent No: 1598438 and, in its preferred form, comprises a substantially circum~erentially rigid central core having an elongate compartment within and extending throughout the length of the core, at least one separate optical ~ibre and/or at least one optical bundle loosely housed in the elongate compartment and, surrounding the central core, at least one layer ox helically wound bare elongate elements of metal or metal alloy.
We have found that, where the overhead flexible electric conductor ox the aforesaid preferred construction has a single layer of bare elongate f ~3~99 elements of metal or metal alloy helically wound around the substantially circumferentially rigid central core ox the conductor, in some circumstances during installation of the overhead flexible electric conductor, whilst stringing of the conductor between towers or other upstanding supports is being effected and the conductor is under tension, before the conductor is secured in dead end clamps there is a qubstantial risk that the bare metal elongate elements of the Mayer will tend to untwist. Any untwisting of the bare metal elongate elements will tend to cause elongation ox the circumferential rigid central core and of the optical fibre and/or optical bundle loosely housed in the elongate compartment of the core because the central core and the optical fibre and/or bundle will try to match the extra length ox the untwisted bare metal elongate elements. Any increase in length of the conductor will seriously decrease the available strain margin of the conductor when it is in service, thereby reducing the long term integrity ox the conductor.
A conductor will normally experience its maximum elongation under heavy loading conditions, such as when the conductor is subjected to severe ice and wind loading. If the strain margin of the conductor is reduced during installation of the conductor to such an extent that it is less than the strain likely to be 3.
incurred during heavy loading, under heavy loading conditions there will be an increase in attenuation of the light transmitting efficiency of any optical fibre and/or optical bundle loosely housed in the elongate compartment of the central core of the conductor.
It i3 an object of the present invention to provide an improved apparatus for stringing between towers or other upstanding supports an overhead flexible electric conductor comprising a substantially circumferentially rigid central core and, surrounding the central core, at least one layer of helically wound bare elongate elements of metal or metal alloy.
According to the invention the improved apparatus compriseq a flexible weighted device which haq means at it endq for connecting the device between the overhead electric conductor and a flexible line and which comprises a flexible elongate member having freely pivotally connected to the member at each of at least two positions spaced along its length a body of such a weight and shape that, when tension is applied to the flexible line to draw the conductor into position and before the conductor is secured to dead end clamps, the body will be suspended downwardly from the flexible elongate member solely under the action of its weight to prevent unacceptable untwisting of the helically wound bare metal elongate elements of said layer or of the ~3~
4~
outermost ox 3aid layers and, a the flexible elongate member i9 drawn in the dirsction ox it3 length through a stringing block, the body will be cau3ed to pivot upwardly to lie alongside and pass through the stringing block with the flexible elongate member, the distance between adjacent pivotally mounted bodies being such that, when the flexible elongate member with a freely pivotally mounted body extending alongside is passing through a stringing block, the or each other body will till be suspended downwardly Prom the flexible elongate member solely under the action ox its welght to prevent unacceptable untwiqting ox said helically wound bare metal elongate elements.
In its preferred Norm, the flexible weighted device comprise a flexible elongate member built up ox at least three flexible rod connected end ko end, each of which rods has pivotally connected to one ox its ends an elongate counterweight having a transverse cross-section ox substantially C-shape, the arrangement being such that when the flexible elongate member i9 drawn in the direction of its length through a stringing block and the elongate counterweight is caused to pivot upwardly to lie alongside its associated flexible rod, the flexible rod will lie between the limb of the C-shaped elongate counterweight. Preferably, alto, each elongate .~ .
~2~
5.
counterweight is pLvotally mounted on its associated flexible rod at or near the leading end of the flexible rod.
Adjacent flexible rods are prefer,~bly interconnected by a rigid connector and, preferably al30, the leading flexible rod has, con,nected to its leading end, a swivel connector for connection to a flexible line and the trailing ~lexlble rod has, connected to its trailing end, a pulling eye or connection to an overhead flexible electric conductor.
Each flexible rod is preferably a teel rod of substantially circular cross-section and each elongate counterweight of substantially C-shaped transverse cross-section is preferably made of lead.
The preferred flexible elongate member is so flexible that it will readily pass through bends of up to 9oo.
The invention is further illustrated by a description 7 by way of example, of a preferred flexible elongate weighted device for use in stringing between towers or other upstanding supports an overhead flexible electric conductor comprising a substantial].y circumferentially rigid central core having throughout it length a bore in which at least one optical ~`ibre is loosely housed, and, surrounding the central core, at least one layer of helically wound bare elongate "I,;"
., , .
'3~3 6.
elements of metal or metal alloy, with reference to the accompanying drawings, in which:-Figure l is a diagrammatic side view of the preferred flexible weighted device, and Figure3 2, 3 and 4, respectively, show side, plan and end view ox one flexible rod and associated counterweight of the flexible weighted device shown in Figure l.
Referring to the drawings, the preferred flexible weighted device comprises a flexible elongate member built up ox three flexible teel rods l ox circular cros3-section, each having an apertured tongue 2 at each of its ends, connected end-to-end by rigid connectors 3.
The leading flexible rod l has, connected to the apertured tongue 2 at its leading end, a swivel connector 4 for connection to a flexible line F and the trailing flexible rod l has, connected to the apertured tongue 2 at its trailing end, a pulling eye 5 for connection to the overhead flexible electric conductor C. An elongate lead counterweight 6 ox ~ub~tantially C shaped transverse cross-section is pivotally mounted near the leading end of each flexible rod l by means ox a pin 7 which extends transversely through overlapping parts of the rod and counterweight.
As shown in Figure l, when using the preferred flexible weighted device in stringing between towers an ,. ..
.. ..
7. 5~
overhead flexible electric conductor C comprising a substantially circum~erentially rigid core having throuhout its length a bore in which at least one optical ~ibre is loosely housed and, surrounding the central core, at least one layer ox helically wound bare elongat.s elements ox metal or metal alloy, the device is interconnected between the conductor and a flexible line F by means of which the conductor is to be pulled under tension into position between adjacent towers and, when tension is applied t.o the flexible line to draw the conductor in position and before the conductor is secured to dead end clamps, each elongate counterweight 6 is suspended downwardly from the device and prevents unacceptable untwisting ox the helically wound bare metal elongate elements ox the layer or ox the outermost ox the layers. As each flexible rod 1 of the device passes in turn through the or each stringing block, the elongate counterweight 6 of the rod pivots upwardly to lie alongside, and pass through the stringing block with, the rod. The distance between adjacent elongate counterweights 6 is such that, when one rod and its elongate counterweight 6 are passing through a stringing block, the other counterweights will still be suspended downwardly prom the device to prevent unacceptable untwisting ox the helically wound bare metal elongate elements.
A
The invention is especially, but not exclusively, concerned with overhead electric and optical transmission and distribution systems of the kind in which the overhead flexible electric conductor or at least one ox the overhead flexible electric conductors includes at least one flexible optical guide. One sueh overhead flexible electric conductor i9 described and claimed in British Patent No: 1598438 and, in its preferred form, comprises a substantially circum~erentially rigid central core having an elongate compartment within and extending throughout the length of the core, at least one separate optical ~ibre and/or at least one optical bundle loosely housed in the elongate compartment and, surrounding the central core, at least one layer ox helically wound bare elongate elements of metal or metal alloy.
We have found that, where the overhead flexible electric conductor ox the aforesaid preferred construction has a single layer of bare elongate f ~3~99 elements of metal or metal alloy helically wound around the substantially circumferentially rigid central core ox the conductor, in some circumstances during installation of the overhead flexible electric conductor, whilst stringing of the conductor between towers or other upstanding supports is being effected and the conductor is under tension, before the conductor is secured in dead end clamps there is a qubstantial risk that the bare metal elongate elements of the Mayer will tend to untwist. Any untwisting of the bare metal elongate elements will tend to cause elongation ox the circumferential rigid central core and of the optical fibre and/or optical bundle loosely housed in the elongate compartment of the core because the central core and the optical fibre and/or bundle will try to match the extra length ox the untwisted bare metal elongate elements. Any increase in length of the conductor will seriously decrease the available strain margin of the conductor when it is in service, thereby reducing the long term integrity ox the conductor.
A conductor will normally experience its maximum elongation under heavy loading conditions, such as when the conductor is subjected to severe ice and wind loading. If the strain margin of the conductor is reduced during installation of the conductor to such an extent that it is less than the strain likely to be 3.
incurred during heavy loading, under heavy loading conditions there will be an increase in attenuation of the light transmitting efficiency of any optical fibre and/or optical bundle loosely housed in the elongate compartment of the central core of the conductor.
It i3 an object of the present invention to provide an improved apparatus for stringing between towers or other upstanding supports an overhead flexible electric conductor comprising a substantially circumferentially rigid central core and, surrounding the central core, at least one layer of helically wound bare elongate elements of metal or metal alloy.
According to the invention the improved apparatus compriseq a flexible weighted device which haq means at it endq for connecting the device between the overhead electric conductor and a flexible line and which comprises a flexible elongate member having freely pivotally connected to the member at each of at least two positions spaced along its length a body of such a weight and shape that, when tension is applied to the flexible line to draw the conductor into position and before the conductor is secured to dead end clamps, the body will be suspended downwardly from the flexible elongate member solely under the action of its weight to prevent unacceptable untwisting of the helically wound bare metal elongate elements of said layer or of the ~3~
4~
outermost ox 3aid layers and, a the flexible elongate member i9 drawn in the dirsction ox it3 length through a stringing block, the body will be cau3ed to pivot upwardly to lie alongside and pass through the stringing block with the flexible elongate member, the distance between adjacent pivotally mounted bodies being such that, when the flexible elongate member with a freely pivotally mounted body extending alongside is passing through a stringing block, the or each other body will till be suspended downwardly Prom the flexible elongate member solely under the action ox its welght to prevent unacceptable untwiqting ox said helically wound bare metal elongate elements.
In its preferred Norm, the flexible weighted device comprise a flexible elongate member built up ox at least three flexible rod connected end ko end, each of which rods has pivotally connected to one ox its ends an elongate counterweight having a transverse cross-section ox substantially C-shape, the arrangement being such that when the flexible elongate member i9 drawn in the direction of its length through a stringing block and the elongate counterweight is caused to pivot upwardly to lie alongside its associated flexible rod, the flexible rod will lie between the limb of the C-shaped elongate counterweight. Preferably, alto, each elongate .~ .
~2~
5.
counterweight is pLvotally mounted on its associated flexible rod at or near the leading end of the flexible rod.
Adjacent flexible rods are prefer,~bly interconnected by a rigid connector and, preferably al30, the leading flexible rod has, con,nected to its leading end, a swivel connector for connection to a flexible line and the trailing ~lexlble rod has, connected to its trailing end, a pulling eye or connection to an overhead flexible electric conductor.
Each flexible rod is preferably a teel rod of substantially circular cross-section and each elongate counterweight of substantially C-shaped transverse cross-section is preferably made of lead.
The preferred flexible elongate member is so flexible that it will readily pass through bends of up to 9oo.
The invention is further illustrated by a description 7 by way of example, of a preferred flexible elongate weighted device for use in stringing between towers or other upstanding supports an overhead flexible electric conductor comprising a substantial].y circumferentially rigid central core having throughout it length a bore in which at least one optical ~`ibre is loosely housed, and, surrounding the central core, at least one layer of helically wound bare elongate "I,;"
., , .
'3~3 6.
elements of metal or metal alloy, with reference to the accompanying drawings, in which:-Figure l is a diagrammatic side view of the preferred flexible weighted device, and Figure3 2, 3 and 4, respectively, show side, plan and end view ox one flexible rod and associated counterweight of the flexible weighted device shown in Figure l.
Referring to the drawings, the preferred flexible weighted device comprises a flexible elongate member built up ox three flexible teel rods l ox circular cros3-section, each having an apertured tongue 2 at each of its ends, connected end-to-end by rigid connectors 3.
The leading flexible rod l has, connected to the apertured tongue 2 at its leading end, a swivel connector 4 for connection to a flexible line F and the trailing flexible rod l has, connected to the apertured tongue 2 at its trailing end, a pulling eye 5 for connection to the overhead flexible electric conductor C. An elongate lead counterweight 6 ox ~ub~tantially C shaped transverse cross-section is pivotally mounted near the leading end of each flexible rod l by means ox a pin 7 which extends transversely through overlapping parts of the rod and counterweight.
As shown in Figure l, when using the preferred flexible weighted device in stringing between towers an ,. ..
.. ..
7. 5~
overhead flexible electric conductor C comprising a substantially circum~erentially rigid core having throuhout its length a bore in which at least one optical ~ibre is loosely housed and, surrounding the central core, at least one layer ox helically wound bare elongat.s elements ox metal or metal alloy, the device is interconnected between the conductor and a flexible line F by means of which the conductor is to be pulled under tension into position between adjacent towers and, when tension is applied t.o the flexible line to draw the conductor in position and before the conductor is secured to dead end clamps, each elongate counterweight 6 is suspended downwardly from the device and prevents unacceptable untwisting ox the helically wound bare metal elongate elements ox the layer or ox the outermost ox the layers. As each flexible rod 1 of the device passes in turn through the or each stringing block, the elongate counterweight 6 of the rod pivots upwardly to lie alongside, and pass through the stringing block with, the rod. The distance between adjacent elongate counterweights 6 is such that, when one rod and its elongate counterweight 6 are passing through a stringing block, the other counterweights will still be suspended downwardly prom the device to prevent unacceptable untwisting ox the helically wound bare metal elongate elements.
A
Claims (6)
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-
1. For use in stringing between upstanding supports an overhead flexible electric conductor comprising a substantially circumferentially rigid central core and, surrounding the central core, at least one layer of helically wound bare elongate elements of metal or metal alloy, a flexible weighted device which has means at its ends for connecting the device between the overhead electric conductor and a flexible line and which comprises a flexible elongate member having freely pivotally connected to the member at each of at least two positions spaced along its length a body of such weight and shape that, when tension is applied to the flexible line to draw the conductor into position and before the conductor is secured to dead end clamps, the body will be suspended downwardly from the flexible elongate member solely under the action of its weight to prevent unacceptable untwisting of the helically wound bare metal elongate elements of said layer or of the outermost of said layers and, as the flexible elongate member is drawn in the direction of its length through any stringing block employed, the body will be caused to pivot upwardly to lie alongside and pass through the stringing block with the flexible elongate member, the 9.
distance between adjacent pivotally mounted bodies being such that, when the flexible elongate member with a freely pivotally mounted body extending alongside is passing through a stringing block, the or each other body will still be suspended downwardly from the flexible elongate member solely under the action of its weight to prevent unacceptable untwisting of said helically wound bare metal elongate elements.
distance between adjacent pivotally mounted bodies being such that, when the flexible elongate member with a freely pivotally mounted body extending alongside is passing through a stringing block, the or each other body will still be suspended downwardly from the flexible elongate member solely under the action of its weight to prevent unacceptable untwisting of said helically wound bare metal elongate elements.
2. A flexible weighted device as claimed in Claim 1, wherein the flexible elongate member is built up of at least three flexible rods connected end-to-end, each of which rods has freely pivotally connected to one of its ends an elongate counterweight having a transverse cross-section of substantially C-shape, the arrangement being such that when the flexible elongate member is drawn in the direction of its length through a stringing block and each elongate counterweight is caused to pivot upwardly to lie alongside its associated flexible rod, the flexible rod will lie between the limbs of the C-shaped elongate counterweight.
3. A flexible weighted device as claimed in Claim 2, wherein each elongate counterweight is freely pivotally mounted on its associated flexible rod near the leading end of the flexible rod.
4. A flexible weighted device as claimed in Claim 2 or 3, wherein adjacent flexible rods are interconnected by a rigid connector.
10.
10.
5. A flexible weighted device as claimed in Claim 2 or 3, wherein the leading flexible rod has, connected to its leading end, a swivel connector for connection to a flexible line and the trailing flexible rod has, connected to its trailing end, a pulling eye for connection to an overhead flexible electric conductor.
6. A flexible weighted device as claimed in Claim 2 or 3, wherein each flexible rod is a steel rod of substantially circular cross-section and each elongate counterweight of substantially C-shaped transverse cross-section is made of lead.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB848422778A GB8422778D0 (en) | 1984-09-10 | 1984-09-10 | Stringing overhead flexible electric conductors |
| GB8422778 | 1984-09-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232599A true CA1232599A (en) | 1988-02-09 |
Family
ID=10566492
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000490269A Expired CA1232599A (en) | 1984-09-10 | 1985-09-09 | Stringing overhead flexible electric conductors |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1232599A (en) |
| GB (2) | GB8422778D0 (en) |
-
1984
- 1984-09-10 GB GB848422778A patent/GB8422778D0/en active Pending
-
1985
- 1985-09-09 CA CA000490269A patent/CA1232599A/en not_active Expired
- 1985-09-10 GB GB08522406A patent/GB2167246B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB8522406D0 (en) | 1985-10-16 |
| GB2167246B (en) | 1987-09-23 |
| GB2167246A (en) | 1986-05-21 |
| GB8422778D0 (en) | 1984-10-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |