QUALITY AND RELIABILITY ANALYSIS OF MEDIUM AND HIGH VOLTAGE CABLE INSULATION USING LIGHT MICROSCOPY METHODS
Journal: NDT WORLD
Volume 19 № 2
, 2016
Rubrics: OPTICAL TESTING
Authors:
Type:
Article
Pages:
from 66
to 71
Status:
Published
Received:
09.06.2016
Accepted:
30.06.2016
Published:
30.06.2016
Language:
Russian
Keywords:
cable insulation, cross-linked polyethylene, ethylene-propylene rubber, light microscopy
Abstract (English):
Introduction. The quality and reliability of polymer insulation of medium and high voltage cables are controlled by factors which reveal themselves on a microscopic level or exhibit microheterogeneity. These factors include: technological microscopic defects, polymer insulation morphology as well as thermal, electrical and electrochemical ageing. Methods. Three groups of light microscopy methods were used for studying the above mentioned factors: visual observation and photomicrography using both common and little-known or forgotten methods (anoptral microscopy, Kachar asymmetric illumination contrast, etc.); microspectral analysis in visible and ultraviolet spectral range, recently – in infrared spectral range; micromanipulation experiment. For each of the investigated factors the article explains the methodology of experimental research including description of experimental equipment and specimens. Some parameters are offered for quantitative estimation of insulation quality. Results. Photomicrographs of defects, morphological units and fluorescence spectra are obtained and presented in the article. It is shown that the manifestation of ageing mechanisms depends on the insulation type. The influence of different insulation areas morphological details on dielectric strength is demonstrated. Discussion. The results have shown the effectiveness of light microscopy methods application for quality and reliability estimation of cable insulating systems. We would also like to emphasize that testing of experimental material specimens in the course of development of advanced cable dielectrics represent a special niche for microscopy application.
Introduction. The quality and reliability of polymer insulation of medium and high voltage cables are controlled by factors which reveal themselves on a microscopic level or exhibit microheterogeneity. These factors include: technological microscopic defects, polymer insulation morphology as well as thermal, electrical and electrochemical ageing. Methods. Three groups of light microscopy methods were used for studying the above mentioned factors: visual observation and photomicrography using both common and little-known or forgotten methods (anoptral microscopy, Kachar asymmetric illumination contrast, etc.); microspectral analysis in visible and ultraviolet spectral range, recently – in infrared spectral range; micromanipulation experiment. For each of the investigated factors the article explains the methodology of experimental research including description of experimental equipment and specimens. Some parameters are offered for quantitative estimation of insulation quality. Results. Photomicrographs of defects, morphological units and fluorescence spectra are obtained and presented in the article. It is shown that the manifestation of ageing mechanisms depends on the insulation type. The influence of different insulation areas morphological details on dielectric strength is demonstrated. Discussion. The results have shown the effectiveness of light microscopy methods application for quality and reliability estimation of cable insulating systems. We would also like to emphasize that testing of experimental material specimens in the course of development of advanced cable dielectrics represent a special niche for microscopy application.
Keywords:
cable insulation, cross-linked polyethylene, ethylene-propylene rubber, light microscopy
cable insulation, cross-linked polyethylene, ethylene-propylene rubber, light microscopy
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