Winding optical cable around existing ground wire

A small diameter heat resistive cable has been developed to establish a new signal transmission system along electric power transmission lines. It is wound onto existing ground wire and has the cross-sectional view shown in Fig. 1. Standard design graded-index or single-mode fibers following CCITT recommendations are stranded to form a six-fiber unit that is filled with thermosetting silicone and covered by fiber reinforced plastic (FRP) for protection from outside mechanical forces. Fluorocarbon resin (PFA) is applied to the outersheath, and it offers excellent weather-and heatresistant characteristics. The outer diameter of the cable is 4 mm; the weight of the cable is 25 kg/km. In addition to basic environmental tests, impulse, short circuit, and vibration tests on the cable wound around ground wire have also been carried out with promising results.