Extended Characterization of an Optical Sag Sensor for High-Temperature Low-Sag Lines

This letter reports on the extended characterization of an optical sag sensor to verify its suitability for monitoring sag and temperature in high-temperature low-sag (HTLS) overhead lines. The sensor utilizes fiber Bragg grating (FBG) technology and can be integrated with the photonic voltage and current sensors that were previously developed by the authors. The response of the sag sensor was evaluated experimentally in the laboratory for temperatures from -20 to 180 degrees C and for forces up to 3 kN. The sensitivities of the sag sensor to force and to temperature estimated from the experiments were around 0.116 nm/kN and 30 pm/degrees C, respectively. The change in the sag sensor sensitivity to force was approximately 25% within the considered temperature range and the change in the sag sensor sensitivity to temperature was 2% within the considered force range. It was demonstrated that the proposed sensor can provide force and temperature measurements within the considered ranges and should be suitable for HTLS lines.