Vacuum Interrupters: Design optimisation requires reliable experimental data

Vacuum interrupter technology is mature with respect to manufacturing quality, reliability and performance. One would expect that this leads to a convergence in terms of conception resulting in a dominating design principle. Yet still a large number of designs and dimensions coexist in the market. Numerical calculation techniques are used to optimise the geometry in order to reduce the overall dimension of the VI. This approach requires criteria for maximum allowable electric field or current density values. Yet a look at the state of the art shows that the maximum allowable electric field may vary at least by a factor of 2 and current density on interruption by 20% depending in a subtle way on process parameters. Mastering these details is the drive to more compact designs and new applications.