High current interruption performance of vacuum interrupter with double-TMF contacts

A new two-contact system with double-TMF structure is investigated regarding its potential for high current interruption. It consists in two co-axial TMF contacts in which the inner contact has a disk-shape structure (spiral contacts) and an outer contact with cup-shape structure. This contacts assembly gives some advantages over the single-TMF contacts one, as the high current constricted arc might split between both, inner and outer contacts or commute to the outer contact and continues its rotation. For both scenarios we normally get a larger distribution of the arc energy over the contacts surface. B-field simulation and Lorentz forces evaluation were carried out to understand the interaction between two assumed co-existing arc columns. Single phase current interruption tests were carried out to compare the performance of double-TMF contacts system with the single-TMF one. The double-TMF vacuum interrupter has revealed superior current interruption performance, 25% higher than the single-TMF one.