GB2167246A - Stringing overhead flexible electric conductors - Google Patents
Stringing overhead flexible electric conductors Download PDFInfo
- Publication number
- GB2167246A GB2167246A GB08522406A GB8522406A GB2167246A GB 2167246 A GB2167246 A GB 2167246A GB 08522406 A GB08522406 A GB 08522406A GB 8522406 A GB8522406 A GB 8522406A GB 2167246 A GB2167246 A GB 2167246A
- Authority
- GB
- United Kingdom
- Prior art keywords
- flexible
- elongate
- conductor
- stringing
- helically wound
- 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.)
- Granted
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
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 C and the trailing end of a flexible pulling line F. This device comprises a flexible elongate member built up of at least three flexible rods 1 connected end-to-end, each of which rods has pivotally connected to one of its ends an elongate counterweight 6 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 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. <IMAGE>
Description
SPECIFICATION
Stringing overhead flexible electric conductors
This invention relates to overhead electric transmission and distribution systems of 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 of 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 of the overhead flexible electric conductors includes at least one flexible optical guide. One such overhead flexible electric conductor is described and claimed in British Patent No: 1598438 and, in its preferred form, comprises a substantially circumferentially rigid central core having an elongate compartment within and extending throughout the length of the core, at least one separate optical fibre and/or at least one optical bundle loosely housed in the elongate compartment and, surrounding the central core, at least one layer of helically wound bare elongate elements of metal or metal alloy.
We have found that, where the overhead flexible electric conductor of the aforesaid preferred construction has a single layer of bare elongate elements of metal or metal alloy helically wound around the substantially circumferentially rigid central core of 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 substantial risk that the bare metal elongate elements of the layer will tend to untwist.Any untwisting of the bare metal elongate elements will tend to cause elongation of 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 of 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 of 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 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 is an object of the present invention to provide an improved method of and 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 method comprises interconnecting between the leading end of the overhead flexible electric conductor and the trailing end of a flexible line by means of which the conductor is to be pulled under tension into position between adjacent towers or other upstanding supports, a flexible weighted device which, when tension is applied to the flexible line to draw the conductor into position and before the conductor is secured to dead end clamps, prevents unacceptable untwisting of the helically wound metal elongate elements of said layer or of the outermost of said layers, the flexible weighted device being of such a construction that it passes through the or each stringing block and, when passing through the stringing block, continues to prevent unacceptable untwisting of said helically wound metal elongate elements.
The invention also includes, for use in the improved method of 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, 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 is of such a construction 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, will prevent unacceptable untwisting of the helically wound bare metal elongate elements of said layer or of the outermost of said layers and that it can pass through the or each stringing block without any detrimental effect on its ability to prevent unacceptable untwisting of said helically wound bare metal elongate elements.
Preferably, the flexible weighted device comprises a flexible elongate member having 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 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 a stringing block, the body will be caused 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 pivotally mounted body extending alongside is passing through a stringing block, the other body or bodies will still be suspended downwardly from the flexible elongate member to prevent unacceptable untwisting of said helically wound bare metal elongate elements.
In its preferred form, the flexible weighted device comprises a flexible elongate member built up of at least three flexible rods connected end to end, each of which rods has 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 the 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. Preferably, also, each elongate counterweight is pivotally mounted on its associated flexible rod at or near the leading end of the flexible rod.
Adjacent flexible rods are preferably interconnected by a rigid connector and, preferably also, 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.
Each flexible rod is preferably a steel rod of substantially circular cross-section and each elongate counterweight of substantially Cshaped 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 90".
The invention is further illustrated by a description, 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 substantially circumferentially rigid central core having throughout its length a bore in which at least one optical fibre is loosely housed, and, surrounding the central core, at least one layer of helically wound bare elongate elements of metal or metal alloy, with reference to the accompanying drawings, in which:
Figure 1 is a diagrammatic side view of the preferred flexible weighted device, and
Figures 2, 3 and 4, respectively, show side, plan and end views of one flexible rod and associated counterweight of the flexible weighted device shown in Figure 1.
Referring to the drawings, the preferred flexible weighted device comprises a flexible elongate member built up of three flexible steel rods 1 of circular cross-section, each having an apertured tongue 2 at each of its ends, connected end-to-end by rigid connectors 3.
The leading flexible rod 1 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 1 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 8 of substantially
C-shaped transverse cross-section is pivotally mounted near the leading end of each flexible rod 1 by means of a pin 7 which extends transversely through overlapping parts of the rod and counterweight.
As shown in Figure 1, when using the preferred flexible weighted device in stringing between towers an overhead flexible electric conductor C comprising a substantially circumferentially rigid core having throuhout its length a bore in which at least one optical fibre is loosely housed and, surrounding the central core, at least one layer of helically wound bare elongate elements of 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 to the flexible line to draw the conductor in position and before the conductor is secured to dead end clamps, each elongate counterweight 8 is suspended downwardly from the device and prevents unacceptable untwisting of the helically wound bare metal elongate elements of the layer or of the outermost of the layers. As each flexible rod 1 of the device passes in turn through the or each stringing block, the elongate counterweight 8 of the rod pivots upwardly to lie alongside, and pass through the stringing block with, the rod. The distance between adjacent elongate counterweights 8 is such that, when one rod and its elongate counterweight 8 are passing through a stringing block, the other counterweights will still be suspended downwardly from the device to prevent unacceptable untwisting of the helically wound bare metal elongate elements.
Claims (10)
1. A method of 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, which method comprises interconnecting between the leading end of the overhead flexible electric conductor and the trailing end of a flexible line by means of which the conductor is to be pulled under tension into position between adjacent towers or other upstanding supports, a flexible weighted device which, when tension is applied to the flexible line to draw the conductor into position and before the conductor is secured to dead end clamps, prevents unacceptable untwisting of the helically wound bare metal elongate elements of said layer or of the outermost of said layers, the flexible weighted device being of such a construction that it passes through the or each stringing block and, when passing through the stringing block, continues to prevent unacceptable untwisting of said helically wound metal elongate elements.
2. For use in stringing between towers and 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, 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 is of such a construction 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, it will prevent unacceptable untwisting of the helically wound bare metal elongate elements of said layer or of the outermost of said layers and that it can pass through the or each stringing block without any detrimental effect on its ability to prevent unacceptable untwisting of said helically wound bare metal elongate elements.
3. For use in stringing between towers and 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, 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 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 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 a stringing block, the body will be caused 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 pivotally mounted body extending alongside is passing through a stringing block, the other body or bodies will still be suspended downwardly from the flexible elongate member to prevent unacceptable untwisting of said helically wound bare metal elongate elements.
4. A flexible weighted device as claimed in
Claim 3, wherein the flexible elongate member is built up of at least three flexible rods connected end-to-end, each of which rods has 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.
5. A flexible weighted device as claimed in
Claim 4, wherein each elongate counterweight is pivotally mounted on its associated flexible rod at or near the leading end of the flexible rod.
8. A flexible weighted device as claimed in
Claim 4 or 5, wherein adjacent flexible rods are interconnected by a rigid connector.
7. A flexible weighted device as claimed in any one of Claims 4 to 8, 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.
8. A flexible weighted device as claimed in any one of Claims 4 to 7, 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.
9. A flexible weighted device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
10. A method of stringing between towers or other upstanding supports an overhead flexible electric conductor substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB848422778A GB8422778D0 (en) | 1984-09-10 | 1984-09-10 | Stringing overhead flexible electric conductors |
Publications (3)
Publication Number | Publication Date |
---|---|
GB8522406D0 GB8522406D0 (en) | 1985-10-16 |
GB2167246A true GB2167246A (en) | 1986-05-21 |
GB2167246B GB2167246B (en) | 1987-09-23 |
Family
ID=10566492
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB848422778A Pending GB8422778D0 (en) | 1984-09-10 | 1984-09-10 | Stringing overhead flexible electric conductors |
GB08522406A Expired GB2167246B (en) | 1984-09-10 | 1985-09-10 | Stringing overhead flexible electric conductors |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB848422778A Pending GB8422778D0 (en) | 1984-09-10 | 1984-09-10 | 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 |
---|---|
GB2167246B (en) | 1987-09-23 |
GB8422778D0 (en) | 1984-10-17 |
CA1232599A (en) | 1988-02-09 |
GB8522406D0 (en) | 1985-10-16 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |