Method of quasi-distributed interface fiber Bragg gratings monitoring dry band arc on the moist pollution layer of composite insulators

Arc discharge on the insulator surface poses a threat to the safe operation of electrical power system. However, effective monitoring technology for arc discharge is lacking. In this paper, a 10 kV composite insulator with 3 x 4 quasi-distributed fiber Bragg gratings (FBGs) embedded at the insulator core-housing interface was developed to monitor dry band arc on the moist pollution layer. The temperature coefficient of interface FBGs was obtained by the temperature calibration test. The interface temperature variation exposed to the instantaneous arc with arc duration of 67 ms and the short-lived arc with arc duration of 2.1 s was observed. Results show that owing to the occurrence of short-lived arc, a new phenomenon was observed: interface temperature drops sharply first, then increases rapidly. Three criteria of ED (Euclidean Distance, i.e. the measuring standard for the otherness of interface temperature of different axial positions), the sharp drop of interface temperature and interface tem-perature rise are proposed to monitor dry band arc. Based on the three criteria, interface FBGs can effectively monitor the instantaneous arc and the short-lived arc. This paper provides a beneficial method for discharge monitoring and flashover warning of composite insulators.