Study on Preparatory Stage of Sheath During the Interruption of Vacuum Interrupters

During the breaking process of a vacuum interrupter, there is a time interval between current zero and generation of recovery voltage. This time interval is variable and matters to the calculation of continuous transition model, but always simplified as a constant. In this article, we put forward the concept of preparatory stage of sheath, analyze the production mechanism and influence on breaking ability, and give the computation method for the duration of this stage. In order to verify the rationality of the theoretical analysis and calculation method proposed in this article, experimental measurement is conducted. The experimental results are in good agreement with the values of duration calculated by the theoretical formula in this article in terms of magnitude and variation law.