Quantification of degradation in nonceramic housing materials by laser ablation

Abstract

A laser irradiation technique has been explored to quantify visible as well as invisible degradation of housing materials used for nonceramic insulators. Nonceramic insulators that were removed from service and new samples of the housing that were subjected to accelerated testing in the laboratory have been evaluated. The method uses a constant power laser source for delivering the same energy to the test specimen. The proposed method is fairly quick and could be looked upon as an additional method for characterizing aging of nonceramic insulators. It has been shown that this method provides a better characterization of aging than is obtained from Fourier Transform Infrared Spectroscopy. The housing materials evaluated include silicone rubber, ethylene propylene diene monomer rubber and cycloaliphatic epoxy resin.

Comparison of laser ablation and inclined plane tracking tests as a means to rank materials for outdoor HV insulators

“…A carbon dioxide laser (Synrad) operating at a wavelength of 10.5 -10.6 µm was used to irradiate the samples [6][7][8]. The power output of the laser was controlled by a PWM controller over the range 2 to 28 W. For safety, the laser was enclosed in a metal interlocked cabinet which was vented externally to remove fumes.…”

“…Inclined plane tracking tests have proved useful in evaluating the performance of a number of silicone rubber based systems [4] and indicate that materials containing a high filler loading are beneficial up to the point where a good dispersion of the filler can be maintained [5]. An alternative testing methodology is to use a laser to apply a known amount of power at a known rate to the sample surface [6][7][8]. However, in order to realistically simulate the thermal damage associated with electrical discharge events [2], an infra-red laser is required [9] and measurements of typical electrical arcs indicate that the local power density needs to be in the range of several watts to several tens of watts, with total energies up to several kJ [10].…”

Arc endurance modeling of polymeric HV outdoor insulating materials

“…Recent publications describe the use of lasers for understanding degradation of popularly used housing materials like silicone rubber, ethylene propylene rubber and epoxy [4][5][6]. This paper is a complimentary effort where the focus is on theoretical modeling of arc endurance under HV outdoor conditions.…”