SF/sub 6/ decomposition under power arcs. I. Physical aspects

For pt.I see ibid., vol.26, no.6, p.1163-76, Dec. 1991. In order to define the origin and the production rate of the CF/sub 4/ formed under the effect of arcing in circuit breakers containing SF/sub 6/ as a gaseous insulator, a series of measurements was taken in two Alsthom circuit breakers in which the gaseous insulator (SF/sub 6/, N/sub 2/), the material from which the nozzle is made (PTFE+CaF/sub 2/, pure PTFE, RPS Ryton R4) and the electrode metal (Cu/W alloy, copper) were changed. Moreover, with the aim of refining the results concerning the influence of the chemical composition of the insulator used to make the nozzle, several insulators (Megelite, PPS Ryton R4, Kel'F, Teflon, polypropylene and nylon) were exposed to sparking in an SF/sub 6/ atmosphere. >