Effect of PTFE dielectric properties on high voltage reactor load switching

There have been sporadic reports over many years of parasitic arcing occurring on PTFE nozzles in high voltage circuit breakers. Recent experimental work has established guidelines for operating conditions likely to enhance such arcing. This contribution provides additional evidence for the role played by the unique properties of PTFE in inducing such parasitic arcing. Electrostatic field calculations are presented which show that field enhancement consistent with the unique dielectric behaviour of PTFE can explain many of the experimentally measured trends. The relevance of the unique behaviour to the operation of and conditions prevail in high voltage interrupters during reactive load duties are also considered