A New System Tested the Dielectric Characteristic of High-Resistance Powder

The dielectric characteristic of high-resistance powder, such as industry powder, chemical raw material, soil and suspended particle in atmosphere, is important to study electrostatic precipitate, electrostatic coating, lightning stroke and contamination flashover of high-voltage equipment. A new test system has been studied. The test range of specific resistivity is from 10¹⁴ Omegaldrcm to 10¹⁴ Omegaldrcm, the test range of voltage is from 0.5 kV to 30 kV (direct current), the least leak current is 10^-9 A, and the range of test temperature is from room temperature to 300degC. By studying on the volt-ampere characteristic, the resistivity characteristic and the electric breakdown characteristic of fly ash burned coal, it is found that the relation among the voltage forced to the ash layer, the leak current flowed to the ash layer and the specific resistivity of fly ash does not always follow the classical ohm´s law, that is, V/I is not always constant. The volt-ampere characteristic curves of fly ash have different shapes while the voltage is in the different phases.