Introduction: Sulphur Hexafluoride (SF6) gas has excellent arc interrupting properties which have lead to it being the only commercially available technology for circuitbreakers in electricity transmission applications. It does, however, have an extremely high global warming potential and its use raises questions on environmental grounds. Much work has been done in the search for alternative gases, but candidates having the appropriate chemical and physical properties also tend to exhibit high global warming potentials. Recent work performed at the University of Liverpool has adopted an alternative approach. An arc interruption technique has been demonstrated that uses chemical components produced in the presence of the arc from solid particulate materials. Its basic performance has been assessed with fault currents of up to 60 kA with moderated rates of rise of recovery voltage of up to 1.2 kV/µs. The work is continuing at present as part of AMRDE 1043 ‘Use and management of SF6’. In the proposed work, the fundamental physical mechanisms of the technique will be studied and the four stages of arc interruption, thermal recovery, dielectric recovery and dielectric withstand will be optimised such that an interrupter unit for transmission applications can be developed. An approach using modelling and experimentation will be adopted and a demonstration unit for transmission usage developed.

Objectives: The project will develop an understanding of the fundamental physical mechanisms of arc quenching by chemical components produced from solid particulate material and subsequently deliver a demonstration interrupter unit for transmission applications that does not require SF6 for its operation.