Interpretation of fracture of a failed in-service 400 kV composite insulator and probable remedy using nonlinear resistive field grading materials Halloum M Ramez1, Reddy B Subba1 1High Voltage Laboratory Dept. of Electrical Engineering, Indian Institute of Science, Bangalore, India Online published on 1 March, 2024. Abstract Recently, composite insulators are getting wider acceptance in distribution and transmission power systems because of their superior characteristics, especially lightweight, high mechanical strength, and better contamination performance. However, local environmental conditions and electrical stress-significantly impact the long-term performance of composite insulators, which could lead to premature-failure. In the present work, physical-chemical analyses are carried out on a decay-like fractured 400 kV composite insulator, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDAX) is conducted to investigate the elemental compositions and structural changes of the FRP rod and SiR housing of the fractured insulator. In addition, measurements, including Dye Penetration Test, Water Diffusion Test, Hardness and Tensile Strength, ESSD, NSSD, and Wettability Class (WC) Measurements, are conducted to evaluate the effect of various stress on the in-service fractured insulator. Further, the fractured insulator is simulated using a 2d axisymmetric model, COMSOL Multiphysics, and the finite element method. The probable fracture mechanism and reasons are discussed, and preventive measures using the nonlinear resistive field grading materials based on-zinc oxide micro varistors is proposed to avoid such failures. Top Keywords Composite insulator, FRP Rod, SiR housing, Nonlinear resistive field grading material (FGM), Finite element method (FEM), Zinc Oxide Microvaristors. Top |