Experimental investigation of internal defect detection of a 69-kV composite insulator

This paper presents an experimental investigation of semi-conductive internal defects present in a 69 kV composite insulator based on E-field measurements. For this purpose, an electro-optic sensor with compact E-field probe was used. In order to simulate the presence of internal defects, an experimental 69 kV composite insulator was specially developed using 3D printing. The results demonstrate that the proposed 69-kV experimental model obtained from 3D printing can be a new alternative for adequate simulation and study of internal defects present in composite insulators. Moreover, these results also show that the actual E-field method used for detecting internal defects can be considerably improved by measuring the radial E-field component close to the rod sheath surface, between insulator sheds. Using this approach, semi-conductive defects with a length equal to 3.5% of the insulator length can be detected both at the HV electrode and floating potential, with is a significant improvement of the sensitivity of actual E-field detection method.