High voltage circuit breaker generating dielectric gas by pyrolytic ac - uses PTFE slug in moving contact giving rise to pyrolytic decomposition under the heat of the arc and hastening extinction

摘要

The heat generated in the plasma of an electric arc during opening of a circuit breaker is used to create a pyrolytic decomposition of a thermoplastic slug of PTFE which hastens the de-ionisation of the arc and speeds its extinction. The slug is introduced in the end of the hollow tube (2) forming the mobile contact of the sulphur hexafluoride filled circuit breaker. To operate the breaker the sealed enclosure contg. the contacts is moved downwards. As it does so a rack on its side drives a pinion to operate a pump which, by forcing dielectric gas through horizontal passages in the contact which remains connected to the mobile contact, sets up a circulation of the PTFE gaseous pyrolytic decomposition products. An upper connection is provided at the end of the travel to, if necessary, earth the electric circuit.