Electric conduction phenomena and carrier mobilitybehavior in mineral base electrical insulating oiland various kinds of synthetic base dielectric fluidshave been investigated in the low voltage region andhave been compared with our results in these fluidscontaining various kinds of oil-soluble impurities.It was shown that the impurities bring about someionic conduction in the fluids, and that the carriermobilities of the fluids containing the impuritiesnot necessarily seem to be governed by Walden's rule,depending on the types of the fluids and the impurities.In contrast, the fluids with industrial puritiesobey the rule. Furthermore, it was suggestedthat an electric conduction mechanism in the fluidscontaining the impurities seems to be closely relatedto a carrier mobility mechanism in these fluids.Thus, it appears advisable that the electricalbehavior of the artificial impurities dissolved in thedielectric fluids should be dealt with apart fromthat of the natural impurities.

Electric Conduction Phenomena and Carrier Mobility Behavior in Dielectric Fluids

Characteristics of streaming electrification in pressboard pipe and the influence of an external electric field

Thermal aging gives the variation of electric and physicochemical properties of mineral base insulating liquid. The liquid was found to mainly consists of various kinds of C16 to C20 hydrocarbons, among which the C18 constituents seems to be selectivity decomposed during the aging. The thermal aging was found to give a shift of the molecular-weight distribution curve, resulting in a increase in average molecular-weight. The conductivity increase was observed owing to the increase in ionic concentration in the liquid. The decrease of carrier mobility can be ~~~~~ ~-

Conference Record of the 1988 IEEE International Symposium on Electrical Insulation, Boston, blA, June 5-8, 1988 THERMAL AGING EFFECTS ON ELECTRICAL AND PHISICOCHEMICAL PROPERTIES OF MINERAL BASE INSULATING LIQUIDS

The variation of electric and physicochemical properties of a mineral base insulating liquid due to thermal aging has been studied. The liquid consisted of various kinds of C/sub 16/ to C/sub 20/ hydrocarbons. The C/sub 18/ constituents seem to selectively decompose during aging. Thermal aging was found to give a shift of the molecular-weight-distribution curve, resulting in an increased average molecular weight. A conductivity increase due to the increase in ionic concentration in the liquid was observed. The decrease of carrier mobility is attributed to an increase of carrier size. >

H. Kane Gae

Papers

Ionic Conductivity Behavior and Ionic Dissociation Energy in Liquid Dielectric under a Low Electric Field