A new packaged FBG sensor for underground cable temperature monitoring

The cable buried in the ground may be affected by the settlement and corrosion of the ground. Due to the existence of cross sensitivity of FBG, these external factors make the FBG have a certain strain which affects the accuracy of temperature monitoring cable. In order to eliminate the influence of strain, temperature package and strain change package for FBG are carried out. In this paper, temperature and strain test of packaged FBG sensor were done by the distributed fiber Bragg grating monitoring system which can monitor the temperature of cable in real time. Compared with bare FBG, the temperature sensitivity is 55.16pm/O and the strain sensitivity is 1.2146*10-5pm/με. The experimental results show that the temperature sensitivity of the system is enhanced and strain sensitivity is greatly reduced. To a certain extent, the temperature strain cross sensitivity is eliminated. Therefore, the system meets the requirement of the application of the temperature on line monitoring of buried cable.