Estimation of the Fatigue Life of a Fiber Bragg Grating Overhead Line Sag Sensor

This paper reports on the investigation that uses the results of overhead line (OHL) sag and vibration measurements by fiber Bragg grating (FBG) based OHL sensors undergoing a field trial in a simulated power network environment to estimate the longevity of the OHL sensors. The maximum tension in the conductor that is transmitted to the sensors is used to simulate the maximum stress in the plates that are used for strain transfer between the conductor and the FBG sensors. Two distinct stainless steel plate designs are considered, and fatigue life is estimated based on the finite element model of the OHL sensors and existing literature fatigue data for stainless steel samples. The FEM analysis of the maximum stress in the mounting plates at the maximum temperature of the conductor showed that there is significant margin to reach the yield tensile stress (YTS) or ultimate tensile stress (UTS) levels of the stainless steel 304. Also at the dynamic operation in the ambient conditions, the stress levels are minimal and below the endurance level of the plates material.