Online Measurement Method for Surface Charges of Basin Insulators Based on the Capacitive Electrostatic Probe

ABSTRACT Operation voltage is disconnected before measuring surface charges on gas‐insulated transmission line (GIL) insulators (i.e., offline measurement). However, the spontaneous dissipation of surface charges reduces the accuracy. In this paper, the input aperture, the diameter, and the height of sensitive electrodes are optimised by the measurement model of electrostatic probes. The electric field distribution, induced potential, and spatial resolution of probes are analysed. The results indicate that the radius of the input aperture and the height of sensitive electrodes should exceed 3 and 11 mm, respectively, to avoid the shielding effect of the grounded shell. Furthermore, the maximum electric field on the sensitive electrode surface reduces with increased diameters. However, there is a positive correlation with heights. Therefore, the radius of the input aperture is 4 mm. The height and the diameter of sensitive electrodes are 12 mm and 1.6 mm, respectively. For ±320 kV GIL basin insulators, the induced potential distribution measured by probes matches the surface charge, and the spatial resolution is 1091mm 2 . This shows that capacitive electrostatic probes are suitable for the online measurement of surface charges on basin insulators, which provides a reference for the prevention of flashovers resulting from surface charge accumulation on DC GIL insulators.