Long-Lifetime Insulation Supporting Board in Tesla-type Generators

A MV-class SF ₆ -insulated supporting board (ISB) for Tesla-type generators is proposed, which has advantages of compact structure and light weight, but its lifetime is short, only 30,000 pulses. Therefore, various techniques are employed to prolong the lifetime, which include grooving on the board surface, elimination of triple junction (TJ) regions, high-temperature drying, and control of water content in the surrounding SF ₆ environment. Each method is respectively researched. Small-scale experimental results demonstrate that grooving can increase the flashover voltage ( U_f ) by 6.3-13.8% and drying at 120°C can increase U_f by 4.3%. Simulation results reveal that eliminating the TJ regions of the assembled ISBs can reduce the maximum applied field ( E_op ) in this region by 50%. Literature review suggests that controlling the water content in the neighboring SF ₆ gas under 500 ppm (part per million) can increase U_f by 2.5%. All the four techniques are applied to a pair of ISBs in a Tesla-type generator, effectively extending the lifetime from 30,000 to million class with an enhancement factor greater than 30.