Development of a non-SF6 self-blast type interrupter unit

This paper presents some experimental results of a model prototype self-blast interrupter unit that uses an alternative gas to SF₆ for its operation. Exploratory work has been undertaken to develop a small-scale test unit and begin to scale up, as well as to optimise its performance for high and low current use in nitrogen gas. In addition, computer modelling has been used to assess the validity of candidate designs. Some of the key design features include the use of a close-fitting PTFE housing to retain high gas pressure for arc blasting as well as the application of PTFE nozzle ablation phenomena to assist the arc extinction process.