Tensile Strength Test And Optical Test Using Pre-twisted Wire Patch Strips
①Cut 50% of the aluminum alloy monofilaments of the outer layer of the OPGW1 optical cable at different locations, i.e. 6 strands, 4 strands at the same location, 2 strands at the same location, and the distance between the two locations is 16.5cm. Then wrap the armor rod preformed repair strip P1 around the outer layer of the cable, and ensure that the breakpoint is wrapped in the center of the repair strip;
②Use two pairs of tension clamps J1 to fix the two ends of the OPGW1 optical cable at both ends of the tensile testing machine;
③Mark the two ends of the preformed armour rod repair strip with a marker;
④Ring all the optical fibers of the OPGW1 optical cable, and connect the optical fibers at both ends to the optical power instrument to test the optical attenuation change;
⑤Start to stretch continuously until the OPGW1 optical cable is broken.
⑥Cut 80% of the aluminum alloy monofilaments of the outer layer of the OPGW2 optical cable at different locations, i.e. 9 strands, 5 strands at the same location, 4 strands at the same location, and the distance between the two locations is 16.5cm. Then wrap the armor rods repair strip P2 around the outer layer of the cable, and ensure that the breakpoint is wrapped in the center of the repair strip;
⑦Repeat the above ②-⑤ steps.
⑧ Breaking force and optical test results
In the simulation test, the number of broken strands of the outer aluminum alloy monofilament of the OPGW optical cable was 50% and 80%, and the armor rods for acsr repair strip was repaired and then broken
Outer layer AA line
Residual RTS
armor rods conductor repair
Original
Repair strip repair
Optical cable code diameter
After breaking strands
Proportion
Strip repaired and broken
Break point position
RTS
Complex proportion
Calculate residual RTS
Force test results
85.4%
95.45 kN
Inside repair strip
97.6%
OPGW1
17.1 97.8kN 50% broken 83.5kN
76.7%
79.40 kN
Inside repair strip
98.6%
OPGW2
15.0 80.2kN 80% broken 61.5kN
The optical power meter displayed no significant change before and after the breaking force test, indicating that the optical attenuation did not change.
(3) Test analysis
Zhongtian Hitachi conducted a series of "simulated OPGW broken strand repair tensile strength tests" on armor rods transmission line repair strips provided by different manufacturers, and the following test conclusions were obtained:
① The repair strength of the armour rod repair strips of each manufacturer can reach at least 95% RTS;
② The attenuation of all test optical fibers did not change significantly, and there was no impact on the optical fiber transmission performance;
③ The optical fiber strain hardly changed, and no additional force was generated on the optical fiber;
④ The tensile strength test of the original OPGW before the repair strength test showed that the test results were all greater than the original RTS, and the distribution of the breakpoints was irregular and discrete. However, the repair strength test results showed that the repair strength of the armour rod in transmission line repair strip could reach at least 95% RTS, but the position of each breakpoint was within the repair strip. The reason may be that the quality of the artificially wound pre-twisted wire repair strip will affect the test results, or the pre-twisted wire repair strip may still have stress concentration, or the outer layer of the adjacent unbroken strands of the OPGW are unevenly stressed after the strand is broken and pulled apart.
Although the pre-twisted wire repair strip fails to reach 100% of the original RTS value of OPGW, due to the large safety margin in the line design, it can reach 95% of the original RTS value, which can meet the line tension sag characteristics and ground wire safety distance requirements.
