High heat-conductivity epoxy casting material for dry power transformer and preparation method thereof

Abstract

The invention discloses a high heat-conductivity epoxy casting material for a dry power transformer and a preparation method thereof. Instead of silicon powder used in the prior art, the high heat-conductivity inorganic powder is used as padding, so that the coefficient of heat conductivity of the casting material is increased. The invention is characterized in that: 1) a toughening agent with higher hydroxyl content is selected, so that the impact resistance and the toughness of cured matters are improved while the acting force between the inorganic powder and the substrate resin molecules is increased; and 2) the formula of the casting material and the technical measures, such as a rubber mixing and de-foaming technology, are optimized, so that the easily sinking phenomenon of the high heat-conductivity inorganic powder caused by higher density is eliminated. The coefficient of heat conductivity of the obtained high heat-conductivity epoxy casting material can reach 1.1-1.3W / (m K); the impact resistance can reach 14-22kJ / m<2>; the difference between the density of the upper part of a workpiece and the density of the lower part of the workpiece is not more than + / -0.5%; the bending strength is 120-140MPa; the coefficient of linear expansion is 30-50*10<-6>K<-1>; the thermal deformation temperature is 105-120 DEG C; and the breakdown field strength is 26-30kV / mm.

Description

technical field [0001] The invention relates to a high thermal conductivity epoxy casting material for a dry-type power transformer and a preparation method thereof. Background technique [0002] Dry-type power transformers are widely used in urban and rural power distribution systems. At present, the insulation system of dry-type power transformer coils mainly has two insulation methods: casting type and resin impregnated type. For castable dry-type transformers, in order to reduce the linear expansion coefficient of the insulating layer, improve the heat transfer performance of the insulating layer, and improve the heat dissipation of the transformer, it is usually necessary to add a certain amount of inorganic powder to the castable. [0003] The inorganic powder added to the castable of the existing castable dry-type power transformer is relatively simple, mainly silicon micropowder or quartz powder. One of the advantages of microsilica powder is its low price, and anot...

AI Technical Summary

Problems solved by technology

[0005] The main difficulty in applying inorganic powders with higher thermal conductivity to castables for dry-type power transformers is that these powders with higher thermal conductivity generally have a higher density, for example, the density of alumina is 3.97g / cm 3 , the density of aluminum nitride is 3.26g / cm 3 , the castable powder is more likely to settle during the curing process