The high pressure arc discharge which is produced in power circuit breakers or at fault point in electric power system is usually contaminated by electrode metal vapor or ablation gas of polymeric materials. The transport and thermodynamic properties of such contaminated gas medium is of much importance for a quantitative analysis on the electrical characteristics of the arc, and its interruption process. In this paper, the electrical and thermal conductivities are calculated for high temperature air contaminated by ablation gas of PTFE material. The PTFE is widely used as nozzle material of circuit breaker or narrow gap of primary cutout. The calculation are carried out under the assumption of thermal equilibrium, in the temperature range from 2, 500 to 30, 000 K, the pressure range from 0.1 to 3.0 MPa and for mass contamination ratio of the PTFE gas from 0 to 100%. The thermodynamic data obtained supply basic information for analyzing the arc inter-ruption process contaminated by the PTFE gas.
This paper describes the electrification on the free surface of low-density polyethylene film due to the lateral motion of charges emitted from the edge of an evaporated silver electrode-The potential distribution on the film surface adjacent to the electrode edge was measured by scanning a probe of electrostatic voltmeter coupled with a computer after the removal of an applied voltage. When a negative voltage was applied to the electrode a region of much wider spread of charges was observed in an atomosphere of nitrogen gas than in air or a mixture of oxgen (20%) and nitrogen (80%) gas. This suggests that the lateral motion of electrons emitted from the electrode is strongly limitted by oxgen molecules absorbed in the surface layer of the film which act as traps. The lateral motion of electrons in the nitrogen atomosphere is con-trolled by an external and space charge fields, and not by diffusion.