Patent ID: 6124549
Filing Date: 2000-09-26
Classification: H02G,Y10T

Abstract:
An electrical stress- controlling composition, comprising:(a) a polymeric matrix, and(b) a particulate filler comprising doped zinc oxide varistor powder; wherein(i) the particles of the filler are calcined at a temperature between 800.degree. C. and 1400.degree. C., and subsequently broken up such that substantially all of the particles retain their original shape,(ii) at least 85% of the weight of the filler comprises zinc oxide,(iii) more than 50% by weight of the filler particles have a maximum dimension of between 5 and 100 micrometers such that the composition has a specific impedance that decreases by at least a factor of 10 when subjected to an electric field increase of less than 5 kV/cm at a region within an electrical field range of 5 kV/cm to 50 kV/cm,(iv) the filler comprises between 5% and 60% of the volume of the total composition; and(v) the particles of the filler are generally spherical.