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Arc discharges of moist polluted composite insulators pose a serious threat to the stable operation of transmission line. However, there is no effective detection technology for arc discharges. The evolution mechanism of interface temperature accompanied by arc discharges is not clear. In this paper, a 10 kV composite insulator with quasi‐distributed fibre Bragg gratings (FBGs) embedded at the insulator core‐housing interface was developed. The temperature calibration experiment of interface FBGs, and the arc discharges experiment of the uniform moist polluted composite insulator were conducted. Applied voltage was controlled to get the continuous arc with an arc time of 46 s and the intermittent arc with an arc time of 8 s. Exposed to the two types of surface arcs, the interface temperature evolution was explored. A new phenomenon of the sharp drop of the interface temperature was observed: the interface temperature first drops sharply and then rises rapidly during the continuous arc. Test results show that quasi‐distributed FBGs are valid for detecting the two types of surface arcs by interface temperature rise. This paper provides a technical means to evaluate the state of surface discharges and insulating properties of composite insulators.

To perfect the wetting mechanism of hydrophobic insulators, it is urgent to explore the impact of hydrophobicity on wetting characteristics of the pollution layer of composite insulators. In this paper, the wetting test of the hydrophobic pollution layer was carried out in artificial hot fog. The local surface conductivity of the pollution layer with different hydrophobicity were measured. The test results show that the local surface conductivities of different hydrophobic pollution layers are obviously different at the same wetting time. For researching the regularity of wetting process in greater detail, three characteristic quantities were proposed to represent the wetting characteristics. They are the duration of local surface conductivity close to zero (DLSCCZ), the saturated wetting time (SWT) and the maximum value of local surface conductivity (MVLSC). With the enhancement of hydrophobicity of the pollution layer, DLSCCZ and SWT increase, while MVLSC and the growth velocity of local surface conductivity both decrease.