A novel optical load cell used in icing monitoring on overhead transmission lines

A novel optical load cell based on Fiber Bragg Grating sensing technique was proposed for icing monitoring on high-voltage overhead transmission lines. Compared to the conventional strain gauge load cell, the developed optical load cell has several unique advantages such as unnecessary power supply on site, excellent ability for avoiding electromagnetic interference, and long lifespan. In the load cell design, coupled dual-beam (‘S’ beam) structure was adopted to achieve an accurate measurement, and the part of FBG bonding was carefully chosen to withstand equal and opposite strain, which solved the problem of cross-sensitivity between strain and temperature of FBG sensing. A mixed WDM/TDM (Wave-Division Multiplexing/Time-Division Multiplexing) optical fiber network is proposed to construct an icing monitoring system containing hundreds of FBGs. Result from the tension experiment indicates that the load cell is sensitive to tension, and the sensitivity and resolution of the load cell is 0.04903 pm/N and 20.4 N. The temperature effect on the tension measurement, evaluated by putting the load cell in a temperature-controlled cabinet, is less than ± 0.175%. Furthermore, in order to investigate the reliability of the load cell in icing environment, an experiment was carried out in a climatic chamber, and the results prove that the load cell can work properly in harsh environment.