Special Issue of the Transactions on Applications of Electrical Insulation and Dielectric Materials

1984 ◽  
Vol EI-19 (2) ◽  
pp. 156-156
Author(s):  
Ivan Kostjukov

The article provides an overview of the most common methods for monitoring the technical state of electrical insulation, based on the applying of absorption phenomena arising in dielectric materials under the influence of DC voltage. The main provisions of the control method based on determining the voltage at the electrodes of the investigated capacitive control object, which is recovering after a short-term discharge of its capacity, are described. The main aspects of the application of the polarization index and the absorption coefficient for determining the technical state of insulation by using the coefficients characterizing the change in time of the current through the dielectric when a constant test voltage is applied to it are analyzed. The advantages of using absorption methods for monitoring the technical state of electrical insulation, first of all, are the ability to carry out testing without the necessity of applying of relatively high test voltages, which greatly simplifies all the necessary technical operations. Such control methods show a significant dependence of the informative parameters used in them on the technical state of insulation on the degree of development of slow polarization processes in the material under study and, therefore, are successfully used to determine the degree of moisture in tested electrical insulation.


Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 592 ◽  
Author(s):  
Xin-Dong Zhao ◽  
Wei-Feng Sun ◽  
Hong Zhao

Modified crosslinked polyethylene (XLPE) with appreciably enhanced DC electrical insulation properties has been developed by chemical modification of grafting chloroacetic acid allyl ester (CAAE), exploring the trapping mechanism of charge transport inhibition. The bound state traps deriving from grafted molecule are analyzed by first-principles calculations, in combination with the electrical DC conductivity and dielectric breakdown strength experiments to study the underlying mechanism of improving the electrical insulation properties. In contrast to pure XLPE, the XLPE-graft-CAAE represents significantly suppressed space charge accumulation, increased breakdown strength, and reduced conductivity. The substantial deep traps are generated in XLPE-graft-CAAE molecules by polar group of grafted CAAE and accordingly decrease charge mobility and raise charge injection barrier, consequently suppressing space charge accumulation and charge carrier transport. The well agreement of experiments and quantum mechanics calculations suggests a prospective material modification strategy for achieving high-voltage polymer dielectric materials without nanotechnology difficulties as for nanodielectrics.


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