GB2199702A - Overhead optical transmission system - Google Patents
Overhead optical transmission system Download PDFInfo
- Publication number
- GB2199702A GB2199702A GB08722023A GB8722023A GB2199702A GB 2199702 A GB2199702 A GB 2199702A GB 08722023 A GB08722023 A GB 08722023A GB 8722023 A GB8722023 A GB 8722023A GB 2199702 A GB2199702 A GB 2199702A
- Authority
- GB
- United Kingdom
- Prior art keywords
- electrically insulating
- transmission system
- optical transmission
- coating
- optical cable
- 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
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4415—Cables for special applications
- G02B6/4416—Heterogeneous cables
- G02B6/4417—High voltage aspects, e.g. in cladding
- G02B6/4419—Preventing corona discharge
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4415—Cables for special applications
- G02B6/4416—Heterogeneous cables
- G02B6/4422—Heterogeneous cables of the overhead type
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/46—Processes or apparatus adapted for installing or repairing optical fibres or optical cables
- G02B6/48—Overhead installation
-
- 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
- H02G7/05—Suspension arrangements or devices for electric cables or lines
- H02G7/053—Suspension clamps and clips for electric overhead lines not suspended to a supporting wire
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Insulators (AREA)
Abstract
In an overhead optical transmission system in which a plastics sheathed optical cable is indirectly suspended from, and is freely supported in long lengths between, towers by metal fittings, risk of failure of the plastics sheathed optical cable due to the existence of a longitudinal electric field in the vicinity of a tower is reduced by providing at least those parts of each metal fitting which are in contact with the plastics sheath of the optical cable with a coating 8, 9 of a wear-resistant, electrically insulating material. Preferably, an electrically insulating surface glaze overlies the coating to seal any pores. The coating is preferably a plasma of flame-sprayed alumina or other suitable refractory material. <IMAGE>
Description
OVERHEAD OPTICAL TRANSMISSION SYSTEM This invention relates to an over head optical transmission system in which one or more than one optical cable comprising at least one optical fibre is freely supported in long lengths between towers, masts or other upstanding supports spaced along the route of the system, the or each optical fibre of the optical cable or cables being suitable for the transmission of light having a wavelength within the range 0.8 to 2.1 micrometres.
When an optical cable having an outer protective sheath of electrically insulating plastics material is freely supported in long lengths between spaced towers, masts or other upstanding supports employed to support ov-erhead electric power transmission lines, it has been found that, in the vicinity of a tower which acts as an earth point, the optical cable is subJected to a longitudinal electric field of about 5V per mm AC. It has been demonstrated that when such an optical cable is subjected to an electric stress of about 7.D'I per mm AC and is exposed to the ASTM D2132 dust and fog test, failure of the optical cable occurs due to erosion of the plastics sheath of the optical cable at positions where the cable is indirectly supported from a tower or other upstanding support by a fitting of metal or metal alloy.
It is an object of the present invention to provide an improved overhead optical transmission system' in which risk of failure of a plastics sheathed optical cable due to the existence of a longitudinal electric field in the vicinity of a tower of the system is substantially reduced.
According to the invention, in an overhead optica transmission system in which an optical cable having an electrically insulating plastics sheath is indirectly suspended by metal fittings from, and is freely supported in long lengths between, towers, masts or other upstanding supports spaced along the route of the system, at least those parts of each metal fitting which are in contact with the plastics sheath of the optical cable have a coating of a wear-resistant, electrically insulating material.
Preferably, substantially the whole of each metal fitting has an overall coating of a wear-resistant, electrically insulating material.
Where there is a risk that the coating of wear-resistant, electrically insulating material on each fitting will be porous, preferably an electrically insulating surface glaze overlies the coating to seal any pores. The coating of wear-resistant, electrically insulating material on each metal fitting preferably is plasma or flame sprayed alumina or other suitable electrically insulating refractory "a'eri^l.
The metal fittings of the system may include suspension clamps and cable grips comprising preformed metal wires.
The plastics sheath of the optical cable preferably is of a substantially electrically non-tracking plastics material.
The invention also includes, for use in an overhead optical transmission system in which an optical cable having an electrically insulating plastics sheath is indirectly suspended by metal fittings from, and is freely supported in long lengths between, towers, masts or other upstanding supports spaced along the route of the system, a metal fitting in.which at least those parts of the fitting which will be in contact with the plastics sheath of the optical cable have a coating of a wear-resistant electrically insulating material.
The invention is further illustrated by a description, by way of example, of two metal fittings suitable for indirectly suspending an optical cable having an electrically insulating plastics sheath from towers, masts or other upstanding supports spaced along the -route of an overhead optical transmission system with reference. to the accompanying drawings, in which:
Figure 1 is a side view of a suspension clamp;
figure 2 is an end view of the suspension clamp shown in Figure 1;
figure 3 is a side view of a cable grip incorporating preformed metal wires, and
Figure 4 is a transverse cross-sectional view of the cable grip taken on the line IV - IV in Figure 3.
Referring to Figures 1 and 2, the suspension clamp comprises a trough-shaped clamp body 1 of an aluminium alloy in which a plastics sheathed optical cable can be clamped by a cover plate 2 and a pair of U-bolts 3. The clamp body 1 can be suspended from a tower or other upstanding support by a two-part strap 4 of galvanised mild steel. Each limb 5 of the strap 4 has a hole 6 which engages one of a pair of trunnions 7 projecting laterally from opposite sides of the clamp body 1 so that the body is free to pivot on the trunnions.
A coating 8 of flame-sprayed alumina over lies the whole of the internal surface of the trough-shaped clamp body 1 and extends over a part of the outer surface of the clamp body at each end of the trough in order to ensure that a plastics sheathed optical cable suspended by means of the clamp will not come in contact with any metal parts of the clamp.A coating 9 of flame-sprayed alumina overlies the whole of the undersurface of the cover plate 2 and , at each end of the cover plate extends over end walls of the plate, again to ensure that a plastics sheathed optical cable suspended by the clay' will not be i n contact wi th any metal surface of --.e ^ a~.p.
The cable grip shown in Figures 3 and 4 comprises an inner layer 11 of preformed helically extending resilient metal wires 12 and an shorter outer layer 14 of preformed helically extending resilient metal wires 15, the lay of the wires 15 of the layer 14 being of opposite hand to the lay of the wires 12 of the inner layer 11. At an intermediate position along the lengths of the layers 11 and 14, a tubular insert 16 of neoprene is positioned between the inner and outer layers. At this intermediate position, a two-part clamp housing 17 is clamped around the inner and outer layers 11, 14 and a U-shaped shackle 18 around the clamp housing can be used to suspend the cable grip from a tower or other upstanding su-pport. Each of the helically wound wires 12 of the inner layer 11 has a circumferentially continuous coating 19 of a wear-resistant , electrically insulating material and each of the helically wound wires 15 of the outer layer 14 has a circumferentially continuous coating 20 of a wear-resistant, electrically insulating material, which coatings ensure that a plastics sheathed optical cable C suspended by the cable grip from a tower or other upstanding support will not be in contact with any metal surface of the cable grip.
In both the suspension clamp illustrated in
Figures 1 and 2 and in the cable grip illustrated in
Figures 3 and 4, the coatings 8 and 9 of flame-sprayec alumina and the coatings 19 and 20 of wear-resistant, electrically insulating ma'erial may each have an overlying coating of an electrically insulating surface glaze to seal any pores in the coating. In both cases, also, the coatings 8 and 9 of flame-sprayed alumina and the coatings 19 and 20 of wear-resistant, electrically insulating material will each be of such thickness that there is negligible risk that a part of the coating will be worn away due to vibration and/or oscillation of the suspended plastics sheathed optical cable.
Claims (10)
1. An overhead optical transmission system in which an optical cable having an electrically insulating plastics sheath is indirectly suspended by metal fittings from, and is freely supported in long lengths between, towers, masts or other upstanding supports spaced along the route of the system, wherein at least those parts of each metal fitting which are in contact with the plastics sheath of the optical cable have a coating of a wear-resistant, electrically insulating material.
2. An overhead optical transmission system as claimed in Claim 1, wherein substantially the whole of each metal fitting has an oyerall coating of a wear-resistant, electrically insulating material.
3. An overhead optical transmission system as claimed in Claim 1 or 2, wherein an electrically insulating surface glaze overlies the coating of wear-resistant, electrically insulating material of each metal fitting.
4. An overhead optical transmission system as claimed in any one of the preceding Claims, wherein the coating of wear-resistant electrically insulating material on each metal fitting is plasma or flame sprayed alumina or other suitable electrically insulating refractory material.
5. An overhead optical transmission system as claimed in any one of the preceding Claims, wherein the metal fittings include suspension clamps.
6. An overhead optical transmission system as claimed in any one of the preceding Claims, wherein the metal fittings include cable grips comprising preformed metal wires.
7. An overhead optical transmission system as claimed in any one of the preceding Claims, wherein the plastics sheath of the optical cable is of a substantially electrically non-tracking plastics material.
8. An overhead optical transmission system in which an optical cable having an electrically insulating plastics sheath is indirectly suspended by metal fittings from, and is freely supported in long lengths between, towers, masts or other upstanding supports spaced along the route of the system, wherein each of at least some of the metal fittings is substantially as hereinbefore described with reference to and as shown in
Figure 1 of the accompanying drawings.
9. An overhead optical transmission system in which an optical cable having an electrically insulating plastics sheath is indirectly suspended by metal fittings fromr and is freely supported in long lengths between, towers, masts or other upstanding supports spaced along the route of the system, wherein each ot least some of the metal fittings is substantially as hereinbefore described with reference to and as shown in
Figure 2 of the accompanying drawings.
10. For use in an overhead optical transmission system in which an optical cable having an electrically insulating plastics sheath is indirectly suspended by metal fittings from, and is freely supported in long lengths between, towers, masts or other upstanding supports spaced along the route of the system, a metal fitting in which at least those parts of the fitting which will be in contact with the plastics sheath of the optical cable has a coating of a wear-resistant, electrically insulating material.
11-. A metal fitting as claimed in Claim 10, wherein an electrically insulating surface glaze overlies the coating of wear-resistant, electrically insulating material.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB868622643A GB8622643D0 (en) | 1986-09-19 | 1986-09-19 | Overhead optical transmission system |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8722023D0 GB8722023D0 (en) | 1987-10-28 |
| GB2199702A true GB2199702A (en) | 1988-07-13 |
| GB2199702B GB2199702B (en) | 1990-04-04 |
Family
ID=10604488
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB868622643A Pending GB8622643D0 (en) | 1986-09-19 | 1986-09-19 | Overhead optical transmission system |
| GB8722023A Expired - Lifetime GB2199702B (en) | 1986-09-19 | 1987-09-18 | Overhead optical transmission system |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB868622643A Pending GB8622643D0 (en) | 1986-09-19 | 1986-09-19 | Overhead optical transmission system |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8622643D0 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2264813A (en) * | 1992-02-26 | 1993-09-08 | Bicc Plc | Overhead optical transmission system |
| CN102237661A (en) * | 2010-04-26 | 2011-11-09 | 江都市曙光电力器材有限公司 | Suspension clamp |
| CN101447656B (en) * | 2008-09-16 | 2011-11-30 | 江苏易鼎电力科技有限公司 | Polymer alloy high energy-saving suspension clamp |
| EP2962026A4 (en) * | 2013-03-01 | 2016-11-02 | Hubbell Inc | Cable suspension clamp |
| CN111181108A (en) * | 2020-03-04 | 2020-05-19 | 广东电网有限责任公司 | Overhead ground wire anti-abrasion device for power transmission line |
-
1986
- 1986-09-19 GB GB868622643A patent/GB8622643D0/en active Pending
-
1987
- 1987-09-18 GB GB8722023A patent/GB2199702B/en not_active Expired - Lifetime
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2264813A (en) * | 1992-02-26 | 1993-09-08 | Bicc Plc | Overhead optical transmission system |
| GB2264813B (en) * | 1992-02-26 | 1995-08-23 | Bicc Plc | Overhead optical transmission system |
| AU670425B2 (en) * | 1992-02-26 | 1996-07-18 | Corning Communications Limited | Overhead optical transmission system |
| CN101447656B (en) * | 2008-09-16 | 2011-11-30 | 江苏易鼎电力科技有限公司 | Polymer alloy high energy-saving suspension clamp |
| CN102237661A (en) * | 2010-04-26 | 2011-11-09 | 江都市曙光电力器材有限公司 | Suspension clamp |
| EP2962026A4 (en) * | 2013-03-01 | 2016-11-02 | Hubbell Inc | Cable suspension clamp |
| AU2014223337B2 (en) * | 2013-03-01 | 2018-10-18 | Corning Cable Systems Llc | Cable suspension clamp |
| CN111181108A (en) * | 2020-03-04 | 2020-05-19 | 广东电网有限责任公司 | Overhead ground wire anti-abrasion device for power transmission line |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2199702B (en) | 1990-04-04 |
| GB8622643D0 (en) | 1986-10-22 |
| GB8722023D0 (en) | 1987-10-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 746 | Register noted 'licences of right' (sect. 46/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19960918 |