Long span all dielectric self-supporting (ADSS) fiber optic cable

Patent metadata

Field	Value
Publication number	US-9323019-B1
Application number	US-201414554710-A
Country	US
Kind code	B1
Filing date	Nov 26, 2014
Priority date	Nov 26, 2014
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A long span ADSS fiber optic cable has an outer jacket, a central tension rod member, and gel-free buffer tubes stranded around the rod member. Each tube is made of a flexible material having a determined elastic modulus, and optical fibers are contained in each tube with a water absorbent material. Water blocking yarns fill voids between the buffer tubes and surround the tubes. An inner jacket envelops the tubes and the yarns, and additional yarns are provided between the inner and the outer cable jackets. The elastic modulus of the buffer tubes is sufficiently high so that the cable sustains a compressive load of at least 220 N/cm over ten minutes with not more than a 0.1 dB increase in attenuation in any fiber. The rod member and the yarns enable the cable to span a distance of approximately 500 to 1050 feet in a NESC Heavy Load district.

First claim

We claim:

1. A long span dielectric self supporting (ADSS) fiber optic cable, comprising:
an outer jacket;
a central tension rod member;
buffer tubes stranded about the tension rod member, wherein each tube is made of a flexible material having a determined elastic modulus;
optical fibers routed with a water absorbent material through each buffer tube;
a first set of first water blocking yarns arranged to fill voids between the buffer tubes and to surround the tubes;
an inner jacket formed to envelop the buffer tubes including the first set of water blocking yarns; and
a second set of water blocking yarns arranged between the inner and the outer jackets of the cable;
wherein the elastic modulus of the buffer tube material is sufficiently high so that the cable sustains a compressive load of at least 220 N/cm over a duration of 10 minutes, and a maximum increase in attenuation for any single-mode fiber in the buffer tubes does not exceed 0.1 dB at 1550 nm during or after release of the compressive load; and
the central tension rod member, the sets of water blocking yarns, and the inner and the outer jackets have sufficient strength to enable the cable to span a distance between a pair of fixed support structures of approximately (i) 500 to 1050 feet in a defined NESC heavy load district, (ii) 800 to 1650 feet in a defined NESC Medium load district, and (iii) 1050 to 2200 feet in a defined NESC Light load district.

2. An ADSS fiber optic cable according to claim 1 , wherein the material forming the buffer tubes is polypropylene.

3. An ADSS fiber optic cable according to claim 2 , wherein the polypropylene material has an elastic modulus of approximately 2110 MPa.

4. An ADSS fiber optic cable according to claim 1 , wherein the outer jacket of the cable is made of medium density polyethylene (MDPE).

5. An ADSS fiber optic cable according to claim 4 , wherein the outer jacket of the cable is 1.4 mm thick.

6. An ADSS fiber optic cable according to claim 1 , wherein the central tension rod member is a fiberglass/epoxy composite rod.

7. An ADSS fiber optic cable according to claim 6 , wherein the outer diameter (OD) of the composite rod is about 2.29 mm, and the rod is upjacketed with MDPE to an OD of about 3.35 mm.

8. An ADSS fiber optic cable according to claim 1 , including a thread arranged to bind the buffer tubes and the first set of water blocking yarns about the tension rod member.

9. An ADSS fiber optic cable according to claim 1 , wherein each buffer tube has an inner diameter (ID) of about 2.0 mm, and an OD of about 3.0 mm.

10. An ADSS fiber optic cable according to claim 1 , wherein the inner jacket of the cable is made of MDPE.

11. An ADSS fiber optic cable according to claim 10 , wherein the inner jacket of the cable is about 0.7 mm thick.

12. An ADSS fiber optic cable according to claim 1 , including six buffer tubes.

13. An ADSS fiber optic cable according to claim 12 , wherein each of the buffer tubes contains 12 optical fibers.

14. An ADSS fiber optic cable according to claim 13 , wherein the weight of the cable per unit length is approximately 121.002 kg/km or 81.31 lb/kft.

15. An ADSS fiber optic cable according to claim 1 , wherein the buffer tubes are arranged in a single circular array around the tension rod member.

16. An ADSS fiber optic cable according to claim 1 , wherein the buffer tubes are arranged in two concentric circular arrays around the tension rod member.

Assignees

• Ofs Fitel Llc

Inventors

• Goddard Timothy
• Weimann Peter A
• Ledbetter Jack
• Norris Richard

Classifications

• G02B6/483

  Installation of aerial type · CPC title

• G02B6/4434 Primary

  Central member to take up tensile loads · CPC title

• G02B6/4427 Primary

  Pressure resistant cables, e.g. undersea cables · CPC title

• G02B6/4433

  Double reinforcement laying in straight line with optical transmission element · CPC title

• G02B6/4494

  Physics · mapped topic