Aging evaluation of silicone rubber insulators using leakage current and flashover voltage analysis

Abstract

Ultraviolet (UV) radiation decreases the hydrophobicity of silicone rubber (SiR) insulators. Lack of hydrophobicity on the surface of such insulators lowers the flashover voltage and increases the Leakage Current (LC) of insulators in the moist environment. This paper presents the artificial UV radiation effects on three types of 20 kV SiR insulators in a chamber with nine UV-C lamps (50 W/m 2 ) for up to 5000 hours.To simulate the moist environment, solid layer method is applied according to IEC 60507 that includes artificial pollution deposition on the insulator surface. Fast Fourier transform of the LC waveforms indicates that the third and the fifth harmonic components are quite sensitive to any incremental discharge on the insulator surface. This sensitivity makes the frequency spectrum of the LC a good criterion to distinguish three distinct SiR insulator situations under the electric stress: 1) no discharge, 2) dry band arcing/corona discharge and 3) continuous arc. Thermogravimetric analysis (TGA) and scanning electron microscope images depict that the polluted insulators include much larger degraded parts under electric stress after aging. Measurements also show that the flashover voltages and the hydrophobicity of aged insulators decrease as the UV exposure time increases for different levels of moisture and pollution.

Superhydrophobic Coatings for Improved Performance of Electrical Insulators

“…This electric arc leads to the onset of thermal breakdown of the die lectric material at lower voltages. [32,[34][35][36] This thermal break down leads to material deterioration, which in turn results in the dielectric breakdown. [37] Consequently, the service life of an insulator is significantly reduced.…”

“…As leakage currents due to corona discharge amplify, the electric arc occurs at lower voltages. This electric arc leads to the onset of thermal breakdown of the dielectric material at lower voltages . This thermal breakdown leads to material deterioration, which in turn results in the dielectric breakdown .…”

Surface roughness condition of field-aged polymer insulators at different installation area

“…It is inevitable factor which depends on the local climate and pollution condition that was experienced by the outdoor insulators at the field of service. These multiple stresses vigorously accelerate degradation that will cause surface tracking [1], weight loss or erosion [6], loss of surface hydrophobicity [7], partial arcs discharge, and increase an electrical leakage current (LC) [8] or complete failure [9].…”

Investigations of Accelerated Aged Polymeric Insulators Using Partial Discharge Signal Measurement and Analysis

“…Surface wettability increases with increase in surface roughness due to aging, which in turn reduces the hydrophobicity. Many researchers reported the role of ambient stresses in the outdoor performance of polymeric insulators [2][3][4][5][6][7][8][9][10]. Among the environmental stresses, the surface degradation effect of water absorption stress and long term thermal stress on energized outdoor insulators is considered to be more severe.…”