Non-destructive analysis of power insulators by frequency response function and three dimensional-computed tomography

• Non-destructive analysis of high voltage insulation detects cracks. • Frequency response analysis detects the changes in the mass density if the pores and cracks appear. • 3D-CT allows one the analysis of crack size of high voltage insulation and internal air gap. • Analysis of internal air gap using 3D-CT. • The proposed approach allows one to detect problems where insulation resistance is not measured. Various techniques are being implemented to analyze outdoor insulators. It plays an important role in the transmission line, and its electrical insulation and mechanical support capabilities must be met at the same time. Mechanical analysis of physical properties and electrical analysis of the threshold voltage to destruction, accounts for a large part. This article focused on detection of pores and crack of insulators by implementing frequency analysis using frequency response function (FRF) an unique non-destructive analysis method, and three dimensional-computed tomography (3D-CT) fault analysis. The purpose of this method is to diagnose insulator defects with non-destructive analysis methods rather than traditional costly breakdown analysis methods. In the case of FRF, the low frequency band stress wave was created up to 35 mm −1 using the Impact Response Test (IRT) using the impact hammer. Due to the difference in the stiffness of the insulator, it moved more than 5.79 μm −1 from the samples B and D that were insulated. For samples, whose insulation was destroyed, a pore size found with 3D-CT was at least 4.88 mm, through which leakage current penetrated The insulating fracture path inside the insulator was formed with a pore diameter of 1.98 to 4.88 mm, through which leakage current penetrates.